Lithium-ion rechargeable battery

Abstract

The present invention provides a positive electrode active material with suppressed phase transitions, and a secondary battery having the same. [Solution] Using a molten salt of MgF2-LiF as a reaction accelerator, lithium cobalt oxide particles To process the material and facilitate the diffusion and doping of magnesium into the lithium cobalt oxide bulk, Furthermore, we developed a novel synthesis method that forms a stable coating layer on the surface of the particles. Ex situ XRD analysis revealed that the modified LiCoO2 was charged to 4.7V. It was confirmed that harmful phase transitions were suppressed and new phases emerged. Modified LiCo O2 exhibited excellent electrochemical performance during high-voltage operation. This technology is fundamental to phase transitions. This provides guidelines for suppressing degradation and realizing ultra-high energy density LiCoO2 cathodes. do.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a product, a method, or a method of manufacture; or, the present invention relates to a process , relating to machines, manufacturers, or compositions of matter One aspect of the present invention relates to an energy storage device including a secondary battery, a semiconductor device, a display device, a light-emitting device, and lighting. This relates to apparatus, electronic equipment, or methods for manufacturing them.

[0002] In this specification, "electronic equipment" refers to all devices that have an energy storage device. Electro-optical devices and information terminal devices with energy storage devices are all electronic devices. [Background technology]

[0003] The advent of portable electronic devices such as smartphones and tablets has dramatically changed human life. It changed. As the functionality of devices continues to be integrated and enhanced, high-capacity rechargeable batteries Demand for lithium cobalt oxide (LiCoO2, hereafter also known as LCO) is continuously expanding. (u) is a high-capacity lithium battery widely used in mobile devices due to its excellent energy density. It remains the most promising candidate for lithium-ion batteries. The theoretical capacity of lithium cobalt oxide is 27 It is 4mAh / g. However, it is charged in a high lithium-free state, i.e., with a high cutoff voltage. This condition degrades battery performance. Therefore, recent lithium cobalt oxide-based products... However, it is forced to be used with a full cell at a cutoff voltage of 4.47V. The above potential is vs. Li + In the case of Li, the potential is approximately 4.55V and the discharge capacity is 200mAh. This corresponds to g.

[0004] Capacity degradation during charge-discharge cycles is due to side reactions on the surface of lithium cobalt oxide, and cobalt Factors include dissolution of the ion, oxygen release, changes in crystal structure, and crack formation. To mitigate degradation at high voltages, elemental doping, surface coating, and electrolyte improvements are being implemented. Various technologies have been applied to lithium cobalt oxide and secondary batteries containing it (non Patent Document 1 to Non-Patent Document 20).

[0005] Lithium cobalt oxide has an α-NaFeO2 (layered rock salt type) crystal structure in the R-3m space group. It is shown and belongs to the O3 phase, characterized by an ABCABC stacking arrangement of oxygen atoms. When lithium is extracted from thium using high voltage, lithium cobalt oxide is released from the O3 phase by H1- It undergoes a phase transition from phase 3 to phase O1 (note that in phase O1, oxygen is stacked ABAB). The H1-3 phase consists of oxygen in the O1 and O3 phases, which are stacked in an ABABCACABCBC pattern. (It is a hybrid). This change involves a structural change corresponding to the displacement of the CoO2 layer, and depends on the crystal. It generates force. This structural change induces crack formation and / or degradation of crystallinity. This may degrade the performance of batteries containing lithium cobalt oxide. Therefore, in particular The cutoff voltage is 4.55V (vs. Li + If the value exceeds / Li, H1-3 is released from the O3 phase. Effectively preventing phase transitions is crucial for achieving stable charge-discharge cycles. This is important. Generally, phase transitions are caused by the electrochemical insertion / deinsertion of cations. Volume changes are common problems that cause degradation of electrochemical properties. Therefore, To effectively mitigate these phenomena, lithium cobalt oxide is not the only cathode active material to use. It is also important for the development of [the product / service]. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] Tukamoto, H. & West, AR Electronic conductivity of LiCoO2 and its enhancement by magnesium doping. J. Electrochem. Soc. 144, 3164-3168 (1997). [Non-Patent Document 2] Bae, JG et al. Structural evolution of Mg-doped single-crystal LiCoO2 cathodes: importance of morphology and Mg-doping sites. ACS Appl. Mater. Interfaces 15, 7939-7948 (2023). [Non-Patent Document 3] Mladenov, M., Stoyanova, R., Zhecheva, E. & Vassilev, S. Effect of Mg doping and MgO-surface modification on the cycling stability of LiCoO2 electrodes. Electrochem. Commun. 3, 410-416 (2001). [Non-Patent Document 4] Jang YI et al. Synthesis and characterization of LiAlyCo1-yO2 and LiAlyNi1-yO2. J. Power Sources 81-82, 589-593 (1999). [Non-Patent Document 5] Luo, W. & Dahn, JR Comparative study of Li[Co1-zAlz]O2 prepared by solid-state and co-precipitation methods. Electrochim. Acta 54, 4655-4661 (2009). [Non-Patent Document 6] Liu, A., Li, J., Shunmugasundaram, R. & Dahn, JR Synthesis of Mg and Mn doped LiCoO2 and effects on high voltage cycling. J. Electrochem. Soc. 164, A1655-A1664 (2017). [Non-Patent Document 7] Zhang, JN et al. Trace doping of multiple elements enables stable battery cycling of LiCoO2 at 4.6V. Nat. Energy 4, 594-603 (2019). [Non-Patent Document 8] Kong, W. et al. Unraveling the distinct roles of Mg occupation on Li or Co sites on high-voltage LiCoO2. J. Electrochem. Soc. 168, 030528 (2021). [Non-Patent Document 9] Shim, JH., Lee, S. & Park, SS Effects of MgO coating on the structural and electrochemical characteristics of LiCoO2 as cathode materials for lithium ion battery. Chem. Mater. 26, 2537-2543 (2014). [Non-Patent Document 10] Cho, J., Kim, YJ & Park, B. Novel LiCoO2 cathode material with Al2O3 coating for a Li ion cell. Chem. Mater. 12, 3788-3791 (2000). [Non-Patent Document 11] Lee, JG, Kim, B., Cho, J., Kim, YW & Park, B. Effect of AlPO4-nanoparticle coating concentration on high-cutoff-voltage electrochemical performances in LiCoO2. J. Electrochem. Soc. 151, A801-A805 (2004). [Non-Patent Document 12] Qian, J. et al. Electrochemical surface passivation of LiCoO2 particles athigh ultravoltage and its applications in lithium-based batteries. Nat. Commun. 9, 4918 (2018). [Non-Patent Document 13] Moon, SH et al. TiO2-coated LiCoO2 electrodes fabricated by a sputtering deposition method for lithium-ion batteries with enhanced electrochemical performance. RSC Adv. 9, 7903-7907 (2019). [Non-Patent Document 14] Taguchi, N., Akita, T., Tatsumi, K. & Sakaebe, H. Characterization of MgO-coated-LiCoO2 particles by analytical transmission electron microscopy. J. Power Sources 328, 161-166 (2016). [Non-Patent Document 15] He, Y. et al. A bi-functional strategy involving surface coating and subsurface gradient co-doping for enhanced cycle stability of LiCoO2 at 4.6 V. J. Energy Chem. 77, 553-560 (2023). [Non-Patent Document 16] Orikasa, Y. et al. Origin of surface coating effect for MgO on LiCoO2 to improve the interfacial reaction between electrode and electrolyte. Adv. Mater. Interfaces 1, 1400195 (2014). [Non-Patent Document 17] Yang, X. et al. Pushing lithium cobalt oxides to 4.7 V by lattice-matched interfacial engineering. Adv. Energy Mater. 12, 2200197 (2022). [Non-Patent Document 18] Takahashi, Y. et al. Structure and electron density analysis of electrochemically and chemically delithiated LiCoO2 single crystals. J. Solid State Chem. 180, 313-321 (2007). [Non-Patent Document 19] Chen, Z., Lu, Z. & Dahn, JR Staging phase transitions in LixCoO2. J. Electrochem. Soc. 149, A1604-A1609 (2002). [Non-Patent Document 20] Van der Ven, A., Aydinol, MK, Ceder, G., Kresse, G. & Hafner, J. First-principles investigation of phase stability in LixCoO2. Phys. Rev. B 58, 2975-2987 (1998). [Non-Patent Document 21] Momma, K. & Izumi, F. VESTA3 for three-dimensional visualization of crystal, volumetric and morphology data. J. Appl. Crystallogr. 44, 1272-1276 (2011). [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] Magnesium doping and coating are used for lithium cobalt oxide at high voltages. It can improve the electrochemical performance of lithium cobalt oxide. Recent research has shown that lithium cobalt oxide can improve electrochemical performance. Mg at the thium site 2+ By doping with ions, the columns between adjacent CoO2 layers are formed. It has been shown that this functions and improves electrochemical performance (Non-Patent Document 14, Non-Patent Document). 17, etc.). However, the electrochemical reversibility of lithium insertion and removal during high-voltage charging is not satisfied. We haven't yet reached the point of being able to add it.

[0008] Therefore, in one aspect of the present invention, the cutoff voltage is 4.55V (vs.Li + Exceeding / Li) One of the objectives is to provide a positive electrode active material in which the phase transition during charging and discharging is suppressed. This refers to a positive electrode active material or composite oxide in which the decrease in discharge capacity during charge-discharge cycles is suppressed. One of the challenges is to provide a product that does not easily break down even after repeated charging and discharging. One of the objectives is to provide an extremely active material or a composite oxide, or to provide a material with a large discharge capacity. One of the objectives is to provide a positive electrode active material or a composite oxide. Alternatively, safety or reliability One of our objectives is to provide highly efficient secondary batteries.

[0009] Another aspect of the present invention relates to a positive electrode active material, a composite oxide, an energy storage device, or a method for producing the same. One of the challenges is to provide it.

[0010] Furthermore, the description of these problems does not preclude the existence of other problems. One embodiment does not need to solve all of these problems. It is possible to extract other problems from the description of the claims. [Means for solving the problem]

[0011] To solve the above problems, in one aspect of the present invention, a molten fluoride salt is used as an additive. Based on this principle, we propose a method for effectively fusing magnesium with lithium cobalt oxide. By incorporating nickel and aluminum as additive elements, the electrochemical stability is further improved. To improve.

[0012] After synthesis, a magnesium-rich rock salt structure appears on the surface of lithium cobalt oxide, It forms a coherent bond with the luck material. Ex situ X-ray diffraction (XRD) analysis. Therefore, lithium cobalt oxide according to one aspect of the present invention does not undergo a transition to the H1-3 phase, 4. A phase transition occurs to the O3 phase compressed at 7V (referred to as the "O3' phase" in this specification, etc.). This can be proven. Lithium cobalt oxide according to one aspect of this invention has a cutoff voltage of 4.6V and After 100 cycles at 4.7V, the capacitance retention rates were 96.4% and 72.7%, respectively. It shows excellent results.

[0013] Furthermore, a mixture of a fluorine-substituted organic solvent and propanesultone was used as the solvent for the electrolyte. By using this material, it is possible to obtain better charge-discharge cycle characteristics even at high cutoff voltages. It can be used as a secondary battery.

[0014] One aspect of the present invention is a compound to which magnesium, fluorine, nickel, and aluminum are added. A positive electrode active material having lithium cobalt oxide, wherein the positive electrode active material has space in the discharge state. It has a layered rock salt type crystal structure belonging to group R-3m, and the layered rock salt type crystal in the discharge state. The structure is such that the lattice constant of the c axis exceeds 14.055 Å, and the space group R-3m is LiCoO2. When fitting and reeling are refined, the GOF (goodness-of- The fit is 1.4 or less, and the positive electrode active material has a surface layer and a bulk region, and the surface layer It has magnesium-rich rock salt structure regions, and the magnesium-rich rock salt structure regions are bulk It is a positive electrode active material that coherently bonds with the region.

[0015] In the above, it is preferable that the lattice constant of the c axis is less than 14.060 Å.

[0016] Another aspect of the present invention involves the addition of magnesium, fluorine, nickel, and aluminum. A positive electrode active material having added lithium cobalt oxide, wherein the positive electrode active material has X-ray photoelectron content In the narrow-scan spectrum of Mg1s obtained by optical method, the coupled energy exhibiting maximum intensity... Ghee is the bond energy at which magnesium oxide exhibits maximum strength, and magnesium fluoride exhibits maximum strength. It is a positive electrode active material that exhibits high binding energy and is located between those two extremes.

[0017] In the above, the positive electrode active material was subjected to narrow-scan measurement of Mg1s by X-ray photoelectron spectroscopy. In the spectrum, the binding energy showing maximum intensity exceeds 1303.3 eV, and 1 It is preferable that the voltage is less than 306.3 eV.

[0018] Furthermore, in the above, the cross-section of the positive electrode active material particles is measured using an electron probe microanalyzer. When analyzed, the Mg / Co (atomic ratio) was between 0.005 and 0.015, and Al / It is preferable that the Co (atomic ratio) is 0.005 or less.

[0019] Another aspect of the present invention involves the addition of magnesium, fluorine, nickel, and aluminum. A positive electrode active material having lithium cobalt oxide added, wherein the positive electrode active material is in a discharge state It has a layered rock salt type crystal structure belonging to space group R-3m, and the positive electrode active material is used as the positive electrode. Lithium metal is used as the negative electrode, and lithium hexafluoride phosphate, ethylene carbonate, and diethyl The electrolyte used is a mixture of carbonate and 2 wt% vinylene carbonate. After performing a charge-discharge cycle test on the cells in a 25°C environment, the discharge state was correct. When the pole was analyzed by powder X-ray diffraction using CuKα1 line, 2θ was between 18.7° and 19.0°. The following conditions must be met: a peak occurs within the specified range, its full width at half maximum is 0.08° or less, and 2θ is 45.0° or greater. A peak occurs in the range of 45.3° or less, with a full width at half maximum of 0.12° or less, and the charge / discharge cycle... The Kur test involves setting the current to 0.5C up to a voltage of 4.7V (however, 1C = 200mA / g must be met). After charging with a constant current (as shown), then charging with a constant voltage until the current value becomes 0.05C, 1 After a 0-minute pause, the battery discharges at a constant current of 0.5C until it reaches a voltage of 2.5V, then pauses for 10 minutes. This is a positive electrode active material that undergoes 100 charge-discharge cycles.

[0020] Furthermore, in the above, the volume energy density calculated using the true density of the positive electrode active material is 425 The gravimetric energy density calculated using the true density of the positive electrode active material is 865Wh or higher, with a density of 0Wh / L or higher. It is preferable that the amount be 1 kg or more.

[0021] Another aspect of the present invention comprises the positive electrode active material described above and an electrolyte, wherein the electrolyte is 5 wt of PS was added to a solution of 1M LiPF6 dissolved in FEC / MTFP (volume ratio 2:8). This is a secondary battery with a certain percentage of additives. [Effects of the Invention]

[0022] According to one aspect of the present invention, the cutoff voltage is 4.55V (vs.Li + Exceeding / Li) This can provide a positive electrode active material in which the phase transition associated with charging and discharging is suppressed. To provide a positive electrode active material or composite oxide in which the decrease in discharge capacity in an electrolytic device is suppressed. This is possible. Alternatively, a positive electrode active material or composite acid whose crystal structure does not easily break down even after repeated charging and discharging. We can provide a composite oxide. Alternatively, we can provide a positive electrode active material or composite oxide with a large discharge capacity. We can provide them. Or, we can provide safe or reliable rechargeable batteries. ru.

[0023] Furthermore, according to one aspect of the present invention, a positive electrode active material, a composite oxide, an energy storage device, or a method for producing the same, is provided. We can provide the law.

[0024] Furthermore, the description of these effects does not preclude the existence of other effects. One embodiment does not necessarily have to possess all of these effects. Furthermore, other effects may be considered. This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings It is possible to extract effects other than those mentioned above from the descriptions in the surfaces, claims, etc. [Brief explanation of the drawing]

[0025] [Figure 1] Figure 1 is a schematic diagram illustrating a method for producing a positive electrode active material according to one aspect of the present invention, as well as the surface and bulk of the positive electrode active material. [Figure 2] Figure 2 is a flowchart illustrating the process for producing a positive electrode active material according to one embodiment of the present invention. [Figure 3] Figures 3(A) and 3(B) are graphs showing the DSC results. [Figure 4] Figures 4(A) through 4(C) are graphs showing the DSC results. [Figure 5] Figures 5(A) and 5(B) are graphs showing the DSC results. [Figure 6] Figure 6 is a schematic diagram illustrating the phase change of the positive electrode active material in a comparative example and in one embodiment of the present invention. [Figure 7] Figures 7(A) and 7(B) illustrate the computational model. [Figure 8] Figures 8(A) to 8(C) illustrate the crystal structure of a positive electrode active material according to one embodiment of the present invention. Figures 8(D) and 8(E) illustrate examples of lithium arrangements. [Figure 9]Figures 9(A) through 9(E) illustrate examples of lithium arrays. [Figure 10] Figure 10 illustrates an example of a lithium array. [Figure 11] Figures 11(A) through 11(C) illustrate examples of lithium arrays. [Figure 12] Figure 12 illustrates an example of a lithium array. [Figure 13] Figures 13(A) to 13(D) illustrate a positive electrode according to one embodiment of the present invention. [Figure 14] Figures 14(A) and 14(B) illustrate a lithium-ion battery according to one embodiment of the present invention. [Figure 15] Figures 15(A) to 15(C) illustrate a lithium-ion battery according to one embodiment of the present invention. [Figure 16] Figures 16(A) to 16(D) illustrate a lithium-ion battery and energy storage system according to one embodiment of the present invention. [Figure 17] Figures 17(A) to 17(C) illustrate a lithium-ion battery according to one embodiment of the present invention. [Figure 18] Figures 18(A) to 18(C) illustrate a lithium-ion battery according to one embodiment of the present invention. [Figure 19] Figures 19(A) to 19(C) illustrate an electric vehicle according to one embodiment of the present invention. [Figure 20] Figures 20(A) to 20(D) illustrate a transport vehicle according to one embodiment of the present invention. [Figure 21] Figures 21(A) to 21(C) illustrate a motorcycle and the like according to one embodiment of the present invention. [Figure 22] Figures 22(A) to 22(D) illustrate an electronic device, etc., according to one embodiment of the present invention. [Figure 23] Figures 23(A) through 23(D) show examples of space equipment. [Figure 24] Figures 24(A) to 24(C) show the XRD patterns of a comparative example and a positive electrode active material according to one embodiment of the present invention. [Figure 25] Figures 25(A) to 25(J) show SEM images, HAADF-STEM images, and microelectron diffraction patterns of a comparative example and a positive electrode active material according to one embodiment of the present invention. [Figure 26] Figures 26(A) to 26(J) show SEM images and SEM-EDX mapping images at each step of the synthesis of a positive electrode active material according to one embodiment of the present invention. [Figure 27] Figures 27(A) to 27(F) show SEM images and SEM-EDX mapping images at each step of the synthesis of a positive electrode active material according to one embodiment of the present invention. [Figure 28] Figure 28 shows the XPS spectra of a comparative example and a positive electrode active material according to one embodiment of the present invention. [Figure 29] Figures 29(A) and 29(B) show the XPS spectra at each step of the synthesis of a positive electrode active material according to one embodiment of the present invention. [Figure 30] Figures 30(A) to 30(C) are graphs showing STEM-EDX elemental mapping images and STEM-EDX radiation analysis results of the surface layer of a positive electrode active material according to one embodiment of the present invention. [Figure 31] Figure 31 shows a STEM-EDX elemental mapping image of the surface layer of a positive electrode active material according to one embodiment of the present invention. [Figure 32] Figures 32(A) and 32(B) show the charge-discharge cycle characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 33] Figures 33(A) and 33(B) are graphs showing the charge-discharge curves and rate characteristics of a half-cell having a comparative example and a positive electrode active material according to one embodiment of the present invention. [Figure 34] Figure 34 is a graph showing the rate characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 35] Figures 35(A) and 35(B) are graphs showing the charge-discharge cycle characteristics and charge-discharge curves of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 36]Figures 36(A) and 36(B) are graphs showing the charge-discharge cycle characteristics of a full cell having a positive electrode active material according to one embodiment of the present invention. [Figure 37] Figures 37(A) to 37(C) show the ex situ XRD patterns of a comparative example and a positive electrode having a positive electrode active material according to one embodiment of the present invention in a discharge state. [Figure 38] Figures 38(A) to 38(H) show SEM images of a comparative example after cycling and of a positive electrode active material according to one embodiment of the present invention. [Figure 39] Figures 39(A) and 39(B) show the cycle characteristics of the cathode active material, as obtained by SEM. [Figure 40] Figures 40(A) to 40(D) ​​show HAADF-STEM images and microelectron diffraction patterns of the surface layer of the positive electrode active material after charge-discharge cycle testing of a comparative example and one embodiment of the present invention. [Figure 41] Figures 41(A) to 41(C) show the ex situ XRD patterns of the positive electrode having the comparative example positive electrode active material in a charged state. [Figure 42] Figures 42(A) to 42(C) show the ex situ XRD patterns of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a charged state. [Figure 43] Figures 43(A) to 43(C) show the ex situ XRD patterns of the positive electrode having the comparative example positive electrode active material in a charged state. [Figure 44] Figures 44(A) to 44(C) show the ex situ XRD patterns of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a charged state. [Figure 45] Figure 45 is a graph showing the dQ / dV curves for charging and discharging of a positive electrode active material according to one embodiment of the present invention. [Figure 46] Figures 46(A) to 46(C) show the ex situ XRD patterns of a positive electrode having a comparative example and a positive electrode active material according to one embodiment of the present invention in a charged state. [Figure 47] Figures 47(A) and 47(B) are graphs showing the charge-discharge cycle characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 48] Figures 48(A) to 48(C) are graphs showing the ex situ XRD patterns of a comparative example and a positive electrode having a positive electrode active material according to one embodiment of the present invention in a charged state. [Figure 49] Figures 49(A) and 49(B) are graphs showing the charge-discharge cycle characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 50] Figures 50(A) and 50(B) are graphs showing the charge-discharge cycle characteristics of a half-cell having a comparative positive electrode active material. [Figure 51] Figures 51(A) and 51(B) are graphs showing the charge-discharge cycle characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 52] Figures 52(A) and 52(B) are graphs showing the charge-discharge cycle characteristics of a comparative example and a half-cell having a positive electrode active material according to one embodiment of the present invention. [Figure 53] Figure 53 is a graph showing the volumetric energy density and gravimetric energy density of a comparative example and a positive electrode active material according to one embodiment of the present invention. [Figure 54] Figure 54 shows the ex situ XRD pattern of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a discharge state. [Figure 55] Figures 55(A) and 55(B) show the ex situ XRD patterns of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a discharged state. [Figure 56] Figure 56 shows the ex situ XRD pattern of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a charged state. [Figure 57] Figures 57(A) and 57(B) show the ex situ XRD patterns of a positive electrode having a positive electrode active material according to one embodiment of the present invention in a charged state. [Modes for carrying out the invention]

[0026] The following describes embodiments for carrying out the present invention with reference to drawings and other images. However, The present invention shall not be construed as being limited to the following embodiments. It is possible to change the mode in which the invention is implemented within the enclosure.

[0027] Furthermore, in the drawings, the size, layer thickness, or area may be exaggerated for clarity. This may be the case. Therefore, it is not necessarily limited to that scale.

[0028] Furthermore, the ordinal numbers used in this specification, etc., as "1st," "2nd," etc., are used for convenience only. It does not indicate the order of processes or stacking order. Therefore, for example, "the first" should be written as "the second". This can be explained by appropriately replacing it with "of" or "the third of," etc. The ordinal numbers described herein do not correspond to the ordinal numbers used to specify one aspect of the present invention. There are cases where this is the case.

[0029] In this specification, the space group is represented by the international notation (or Hermann-Mauguin notation) S. The notation is written using hort notation. Miller indices are also used to indicate crystal planes and crystals. Direction is indicated. In crystallography, space groups, crystal planes, and crystal directions are indicated by superscript numbers. A bar is used, but in this specification, due to formatting constraints, instead of placing a bar above the number, it is placed before the number. It is sometimes expressed with a minus sign (-). Also, individual orientations that indicate direction within the crystal. [ ] represents the set of orientations that show all equivalent directions, < > represents the set of orientations, and ( ) represents the individual planes that show crystal faces. Therefore, sets of surfaces with equivalent symmetry are represented by {} respectively. They are also represented by the space group R-3m. The trigonal crystal structure is generally represented as a composite hexagonal lattice of a hexagonal crystal for ease of understanding. Sometimes, (hkil) is used as the Miller exponent in addition to (hkl). Here, i is -(h+k). In this specification, the space group R-3m is not specifically stated. Unless otherwise specified, crystal faces and other features are represented using a composite hexagonal lattice.

[0030] In this specification, when simply referring to a positive electrode active material, it means that multiple positive electrodes are formed by analytical methods, etc. There are two ways to describe active material particles: one is to describe active material particles, and the other is to describe a single positive electrode active material particle. For example, a scanning transmission electron microscope-energy dispersive X-ray detector (STEM-EDX) Line analysis, STEM-electron energy loss spectroscopy (STEM-EELS), and electron diffraction In the case of descriptions relating to a single positive electrode active material particle, unless otherwise specified, the description refers to a single positive electrode active material particle. In the case of X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), various mass spectrometry methods, etc., there is no particular reason to say If not, the description concerns multiple positive electrode active material particles.

[0031] In this specification, the term "particle" is not limited to spherical particles (those with a circular cross-sectional shape), The cross-sectional shape of individual particles can be elliptical, rectangular, trapezoidal, triangular, square with rounded corners, or asymmetrical. Examples include shape, and individual particles may have irregular shapes. Also, the term "particle" is used to describe the field. A combination of primary and secondary particles.

[0032] Furthermore, when describing the characteristics of the particles of the positive electrode active material, it is not always necessary to describe all particles as possessing those characteristics. It is not necessary to have them. For example, of the three or more particles of the positive electrode active material selected randomly, 5 0% or more, preferably 70% or more, and more preferably 90% or more, possess the following preferred characteristics. If present, it has the effect of sufficiently improving the characteristics of the positive electrode active material and the secondary battery having it. It can be said that it is possible.

[0033] The distribution of a certain element refers to the region where the element is continuously detected within the range that is not noise by a certain continuous analysis method. The region continuously detected within the range that is not noise can also be defined as, for example, the region that is always detected when the analysis is performed multiple times.

[0034] In this specification and the like, the added element is synonymous with the mixture and a part of the raw material.

[0035] The theoretical capacity of the positive electrode active material refers to the amount of electricity when all the insertable and removable lithium in the positive electrode active material is removed. For example, the theoretical capacity of LiCoO2 is 274 mAh / g, the theoretical capacity of LiNiO2 is 275 mAh / g, and the theoretical capacity of LiMn2O4 is 148 mAh / g.

[0036] Also, the degree to which the insertable and removable lithium remains in the positive electrode active material is indicated by x in the composition formula. For example, in Li MO2 (where M is one or more selected from cobalt, nickel, and manganese). In the case of the positive electrode active material in a secondary battery, x = (theoretical capacity - charged capacity) x / theoretical capacity. For example, when a secondary battery using LiMO2 as the positive electrode active material is charged to 19.2 mAh / g, it can be said that Li MO2 or x = 0.2. When x in Li MO2 is small, for example, it means 0.1 < x ≤ 0.24. Also, the amount of lithium desorbed from the positive electrode active material relative to the theoretical capacity may be indicated as the depth of charge. In this specification and the like, the depth of charge = 1 - x. 0.2 x When x in LiMO2 is small, for example, it means 0.1 < x ≤ 0.24. Also, the amount of lithium desorbed from the positive electrode active material relative to the theoretical capacity may be indicated as the depth of charge. In this specification and the like, the depth of charge = 1 - x.

[0037] For example, appropriately synthesized lithium cobaltate before being used in the positive electrode has a stoichiometric ratio of approximately ​​​​​​When it is full, it is LiCoO₂ and x = 1. Also, the lithium cobaltate contained in the secondary battery after the discharge ends can also be said to be LiCoO₂ with x = 1. The end of the discharge mentioned here refers to a state where, for example, at a current of 100 mA / g or less, the voltage becomes 3.0 V or 2.5 V or less.

[0038] Li x The charge capacity and / or discharge capacity used for calculating x in LiMO₂ are preferably measured under conditions where there is no or little influence of short circuit and / or decomposition of the electrolyte solution, etc. For example, data of a secondary battery in which a rapid change in capacity regarded as a short circuit has occurred should not be used for calculating x.

[0039] Also, the space group of the crystal structure is identified by XRD, electron diffraction, neutron diffraction, etc. Therefore, in this specification, etc., belonging to a certain space group, being attributed to a certain space group, or being a certain space group can be rephrased as being identified as a certain space group.

[0040] Also, if the arrangement of anions is approximately close to cubic close packing, it can be regarded as cubic close packing. The arrangement of anions in cubic close packing means that the second layer of anions is arranged above the voids of the anions filled in the first layer, and the third layer of anions is located directly above the voids of the second layer of anions and not directly above the first layer of anions. Therefore, the anions do not necessarily have to be in a strict cubic lattice. Also, since real crystals always have defects, the analysis results do not necessarily have to be as theoretical. For example, in an electron diffraction pattern or an FFT (Fast Fourier Transform) pattern such as a TEM image, spots appear at positions slightly different from the theoretical positions. (高速フーリエ変換)パターンにおいて、理論上の位置と若干異なる位置にスポットが現 It is acceptable if the azimuth deviation from the theoretical position is 5 degrees or less, or 2.5 degrees or less. If so, it can be said that it adopts a cubic close-packed structure.

[0041] Additionally, additive elements that improve conductivity and / or additive elements that stabilize the crystal structure are added. The added positive electrode active material is referred to as a composite oxide, positive electrode material, positive electrode material, positive electrode material for secondary batteries, etc. In some cases, the positive electrode active material of one embodiment of the present invention has a compound. It is preferable to do so. Furthermore, in this specification, the positive electrode active material of one aspect of the present invention is composed of It is preferable to have. Furthermore, in this specification, the positive electrode active material of one aspect of the present invention is a composite It is preferable that it has a body.

[0042] As the charging voltage of a secondary battery increases, the voltage at the positive electrode generally increases. In one aspect of the present invention... The positive electrode active material has a stable crystal structure even at high voltages. The stable crystal structure of the material suppresses the decrease in charge / discharge capacity that occurs with repeated charging and discharging. It is possible.

[0043] Unless otherwise specified, the materials used in secondary batteries (positive electrode active material, negative electrode active material, electrolyte, The condition of separators, etc., before deterioration shall be described. The decrease in discharge capacity due to aging and burn-in processes is not considered degradation. Let's assume we don't call them that. For example, lithium-ion secondary single cells and lithium-ion secondary battery packs. (Hereinafter referred to as lithium-ion secondary battery) A battery having a discharge capacity of 97% or more of its rated capacity This can be described as the state before degradation. The rated capacity is for lithium-ion batteries for portable devices. For rechargeable batteries, JIS C 8711:2019 must be followed. Other lithium-ion batteries must comply with this standard. In the case of secondary batteries, in addition to the JIS standards mentioned above, various JIS and IE standards apply to electric vehicle propulsion, industrial use, etc. It conforms to the C standard, etc.

[0044] In this specification, etc., the state of a secondary battery before the deterioration of its materials is referred to as the initial product, or This is referred to as the initial state, and the degraded state (having a discharge capacity of less than 97% of the rated capacity of the secondary battery) The state in which the item is used or in use, or a used item or a used state) It is sometimes referred to as such.

[0045] (Embodiment 1) In this embodiment, Figures 1 to 12 illustrate a method for producing a positive electrode active material according to one aspect of the present invention. The characteristics of the positive electrode active material will be described. For brevity, the figures will show one embodiment of the present invention. The positive electrode active material is sometimes written as MFNA-LCO, based on the initial letters of the added elements.

[0046] The positive electrode active material in one aspect of the present invention is magnesium, fluorine, nickel, and aluminum. It has lithium cobalt oxide to which is added. However, lithium cobalt oxide (LCO, LiC The composition of oO2 is not strictly limited to Li:Co:O=1:1:2.

[0047] The positive electrode active material in one aspect of the present invention is a layered rock salt belonging to space group R-3m in the discharge state. It has a crystal structure of type . In this crystal structure, the lattice constant of the c axis exceeds 14.055 Å, and 14 It is less than 0.060 Å. Note that the crystal structure analysis of the positive electrode active material in the discharge state was performed using a GOF of 2. It is preferably 0 or less, and more preferably 1.4 or less.

[0048] The positive electrode active material of a lithium-ion secondary battery maintains charge neutrality even when lithium ions are inserted and removed. To maintain this, it is necessary to have a transition metal that can undergo oxidation and reduction. A positive electrode active material according to one aspect of the present invention For quality, it is preferable to use cobalt as the transition metal responsible for the oxidation-reduction reaction. Of the transition metals present, cobalt is 95 atomically or more, preferably 98 atomically. If the mic% is 1% or higher, and more preferably 99% or higher, the synthesis is relatively easy. It is desirable because it has many advantages, such as being easy to handle and having excellent cycle characteristics.

[0049] A positive electrode active material according to one aspect of the present invention has a surface layer and a bulk layer. It also has grain boundaries. There are cases where this occurs.

[0050] In this specification, the surface layer of the positive electrode active material refers to the area perpendicular to the bulk from the surface. This refers to a region within 10 nm that is approximately perpendicular. Therefore, the surface layer includes the surface. Note that "approximately perpendicular" means The angle should be between 80° and 100°. Surfaces created by closed cracks and / or fissures should also be shown. It can be called a surface. The surface layer is synonymous with the vicinity of the surface, the region near the surface, or the shell, and is the outermost surface. Includes.

[0051] Furthermore, the region deeper than the surface layer of the positive electrode active material is called the bulk. The bulk is the same as the interior or core. It is righteous.

[0052] Furthermore, a grain boundary is, for example, a region where particles of the positive electrode active material are fixed together, or within the positive electrode active material. The areas where the crystal orientation changes, i.e., the repetition of bright and dark lines in STEM images, are discontinuous. This refers to areas that have become distorted, areas containing many crystal defects, areas with disordered crystal structures, etc. A defect is a defect that can be observed in cross-sectional TEM (transmission electron microscope) images, cross-sectional STEM images, etc. This refers to structures where other atoms are interposed between lattice layers, such as cavities. Grain boundaries are surface defects. It can be said that this is one of them. Also, the vicinity of the grain boundary refers to the region within 10 nm of the grain boundary. do.

[0053] A positive electrode active material according to one aspect of the present invention comprises magnesium, fluorine, nickel and other additive elements. It contains aluminum in its surface layer. Furthermore, the amount of additive elements detected in the surface layer is higher than in the bulk. It is preferable.

[0054] Furthermore, if the positive electrode active material of one aspect of the present invention has grain boundaries, the added element magnesium Having at least a portion of fluorine, nickel, and aluminum near the grain boundaries. Preferably, the amount of additive elements detected near the grain boundaries is different from the surface layer and the area near the grain boundaries. It is preferable that it be higher than the portion.

[0055] Furthermore, in the bulk positive electrode active material according to one embodiment of the present invention, a preferred amount of additive elements is used. No. Magnesium is preferred to be present in small amounts in the bulk to suppress the phase transition, which will be discussed later. It is preferable that nickel is also present in small amounts in the bulk. However, fluorine and aluminum It is preferable that nium is either absent or undetectable in the core of the bulk material. While elemental additives are necessary to suppress phase transitions, their excess presence in the bulk reduces crystallinity. This is because it can lead to disadvantages such as a decrease in charge and discharge capacity.

[0056] Therefore, an electron probe microanalyzer (EPMA) can be used to analyze the positive electrode active material of one aspect of the present invention. When analyzing the bulk cross-section of the cosmic particles, the Mg / Co (atomic ratio) is between 0.005 and 0.01. It is preferable that the ratio is 5 or less. Also, the Ni / Co (atomic ratio) should be 0.002 or more and 0.05 or less. It is preferable that the value be below the limit, and more preferably 0.03 or more and 0.01 or less.

[0057] Furthermore, in bulk, the F / Co (atomic ratio) is preferably 0.01 or less. It is preferable that no elements are detected. The Al / Co (atomic ratio) is 0.005 or less. It is preferable that aluminum is not detected, and it is even more preferable that aluminum is not detected.

[0058] Lithium cobalt oxide is easily thermally decomposed in air at temperatures above 950°C. However, acid Magnesium oxide (MgO) is extremely thermally stable, with a melting point of 2852°C. Even if lithium cobalt oxide and magnesium oxide powder are heated below the decomposition temperature of lithium, In conventional mixing and firing processes, solid reactions tend to be uneven and time-consuming. Therefore, Conventional doping and coating technologies involve the introduction of magnesium into lithium cobalt oxide. Entry was difficult.

[0059] Therefore, the inventors investigated the diffusion of magnesium into lithium cobalt oxide bulk and doping To facilitate this process, we decided to use molten fluoride salts. In this method, the bulk is magnesium As nesium is dispersed, the surface layer of lithium cobalt oxide particles absorbs excess magnesium. It is coated by [a certain method].

[0060] Figure 1 shows a positive electrode active material according to one embodiment of the present invention, which uses a fluoride that acts as a reaction accelerator. This shows the manufacturing method and schematic diagrams of the surface and bulk of the positive electrode active material. The surface layer is magnesium-rich. It has a rock salt structure region, which is coherently bonded to the bulk region. A schematic diagram of the reaction accelerator was drawn using VESTA (Non-Patent Literature 21). By using a fluoride that acts as a fluoride, the surface layer of lithium cobalt oxide particles and the bulk material can be treated. This enables the effective diffusion and doping of additive elements, including magnesium. can.

[0061] As fluorides that act as reaction accelerators, fluorides of typical metal elements are preferred. For example, lithium fluoride (LiF), sodium fluoride (NaF), and potassium fluoride ( KF) and mixtures thereof have a melting point close to the decomposition temperature of lithium cobalt oxide, and cobalt It is preferable because its decomposition temperature is lower than that of lithium oxate and it is also safer. Lithium-ion batteries Considering its use in this application, lithium fluoride is used as the fluoride that acts as a reaction accelerator. It is especially preferable to do so.

[0062] Figure 2 is a flowchart illustrating an example of a method for producing a positive electrode active material according to one aspect of the present invention. The six samples marked with an asterisk in the figure were analyzed using XPS and SEM-EDX in Example 1. The analysis was conducted. However, the present invention is not limited to the method shown in Figure 2. For example, heating temperature and The heating time and temperature should be sufficient for the melting of the fluoride used as a reaction accelerator, The temperature and time must not lead to the decomposition of lithium cobalt oxide. The heating time is determined by the raw material lithium cobalt oxide (hereafter referred to as pristine LCO or original The optimal range may vary depending on the particle size (also called LCO). It can be added at the same time, or it can be added in multiple steps. The timing depends on the element. You can change it.

[0063] ≪DSC≫ Figures 3(A) to 5(B) show the results of differential scanning calorimetry (DSC). Measurements were taken using ThermoPlus (EVO2 DSC8271, Rigaku) ​​from room temperature to 1000°C. The heating was carried out at a rate of 20°C / min to ℃. Alumina pan (φ5mm × 2.5mm) was used. Al2O3 powder was used as a reference.

[0064] Figure 3(A) shows the DSC results of a mixture of MgF2 powder and LiF powder in a 3:1 (molar ratio). The melting onset temperature was 731.4°C, and the melting peak temperature was 739.3°C. This indicates the eutectic point of MgF2 and LiF. Therefore, the temperature proposed in this specification ( When exposed to temperatures such as 900°C, these compounds transition from a solid phase to a liquid phase and transform into molten salts. To transform.

[0065] Figure 3(B) shows the DSC results for Mg(OH)2 powder. The decomposition start temperature was 357.6°C. The maximum decomposition temperature was 418.8°C.

[0066] Figure 4(A) shows the DSC measurement results of the original LCO powder. Figure 4(B) shows the original LCO and Li DSC of a sample prepared by mixing F and MgF2 powders in a molar ratio of 1:0.003:0.01 These are the measurement results. Figure 4(C) is an enlarged view of the area enclosed by the dotted rectangle in Figure 4(B). The initial reaction temperature was 778.6°C, and the peak reaction temperature was 814.5°C. These were cobalt. At a temperature slightly lower than the decomposition temperature of lithium trioxide, eutectic formation of MgF2 and LiF occurs, as shown in Figure 3(A). Higher than the point (731.4℃). The surface of lithium cobalt oxide particles contains magnesium fluoride. This suggests that it is reacting with the liquid in the substance.

[0067] Figure 5(A) shows the original LCO and Mg(OH)2 powders mixed in a 1:0.01 (molar ratio). This is the DSC result for the case. Figure 5(B) is an enlarged view of the area enclosed by the dotted rectangle in Figure 5(A). The reaction initiation temperature was 345.0°C, and the reaction peak temperature was 363.9°C.

[0068] As shown in Figures 5(A) and 5(B), the original mixture of LCO and Mg(OH)2 is D The SC results showed an endothermic peak at 363.9°C. This was observed in Figure 3(B). The decomposition temperature of Mg(OH)2 alone (357.6°C) is almost the same as that of the original LCO and Mg No peaks suggesting the eutectic point of (OH)2 were observed.

[0069] During the heating process in the manufacturing process as shown in Figure 2, the surface layer of the lithium cobalt oxide particles and the molten part The magnesium oxide salt partially melts, and the added elements, including magnesium, diffuse effectively. And doping is performed. As a result, the phase change involving the shearing of the CoO2 layer is suppressed, and the present invention In one embodiment, the positive electrode active material has a structure that differs from the original LCO in a highly delithified state.

[0070] Figure 6 is a diagram illustrating the phase change between the original LCO and the positive electrode active material according to one embodiment of the present invention. LCO charges up to 4.55V (Li x In CoO2, (x < 0.3) H1- from the O3 phase It is known to undergo a phase transition to a third phase. This phase transition corresponds to a shift in the CoO2 layer. It involves structural changes. Furthermore, these two crystal structures also have a large difference in volume. When comparing per unit, the charged state H1-3 phase and the discharged state lithium cobalt oxide (O3 The volume difference between the phases exceeds 3.5%, and is typically 3.9% or more.

[0071] However, in one embodiment of the present invention, the positive electrode active material, in a highly delithified state, The presence of magnesium substituted into the layer provides structural support, preventing the CoO2 layer from shifting. Furthermore, the phase transition from the O3 phase to the H1-3 phase is suppressed. In addition, the shift is probably on the surface of the LCO. It begins with a magnesium-rich rock salt region present on the surface of the positive electrode active material according to one embodiment of the present invention. This may suppress the effect.

[0072] A positive electrode active material according to one aspect of the present invention is 4.7V(vs.Li + Transition to H1-3 phase at / Li) Without doing so, it undergoes a phase transition to the phase referred to as the O3' phase in this specification.

[0073] The crystal structure of the O3' phase belongs to space group R-3m, and the cobalt and oxygen in the unit cell The coordinates are within the range Co(0,0,0.5), O(0,0,x), and 0.20≦x≦0.22. This can be shown as follows. Also, the lattice constant of the unit cell is: The a-axis is 2.798 ≤ a ≤ 2.838 (Å) is preferred. 2.808 ≤ a ≤ 2.828 (Å) is more preferable, and typically a = 2.818 (Å). The C axis is 13.566 ≤ c ≤ 13.766 (Å) is preferred. 13.636 ≤ c ≤ 13.696 (Å) is more preferable, and typically c = 13.666 (Å).

[0074] In the O3' phase, ions such as cobalt, nickel, and magnesium occupy the 6-coordinate position of oxygen. Note that light elements such as lithium and magnesium may occupy the oxygen 4-coordinate position. ru.

[0075] Furthermore, the difference in volume per unit number of cobalt atoms between the O3 phase and the O3' phase in the discharged state is 2.5%. More specifically, the percentage is 2.2% or less, and typically 1.8%.

[0076] Furthermore, in one embodiment of the present invention, the positive electrode active material is prepared using fluoride as a reaction accelerator. Therefore, it is preferable that fluorine be detected in the surface analysis of the positive electrode active material. For example, by X-ray. It is preferable that fluorine is detected by photoelectron spectroscopy (XPS). Furthermore, fluoride One indicator that the material has gone through a molten salt stage is that it has different bonding energies than the compound used as the material. It is preferable that it exhibits ghee.

[0077] For example, a narrow scan of Mg1s of a positive electrode active material according to one embodiment of the present invention obtained by XPS. In the spectral measurements, both magnesium oxide and magnesium fluoride showed bonded energy. It is preferable to exhibit a maximum value different from that of ghee. More specifically, the positive electrode active material of one aspect of the present invention The narrow scan spectrum of quality Mg1s shows magnesium oxide and magnesium fluoride. It is preferable that the maximum value is shown between the binding energy and the bond energy.

[0078] In one embodiment of the present invention, the positive electrode active material suppresses harmful phase transitions accompanied by CoO2 layer shifting. Therefore, 4.7V (vs. Li + Charge / discharge cycle test with a high cutoff voltage of / Li) Even after undergoing this process, the degradation of the crystal structure is extremely minimal.

[0079] Specifically, the positive electrode active material according to one aspect of the present invention is used as the positive electrode, and lithium metal is used as the negative electrode. Lithium hexafluoride phosphate, ethylene carbonate, and diethyl carbonate in a 2 wt% solution. For cells using an electrolyte solution containing vinylene carbonate, under a 25°C environment Below, after performing a charge-discharge cycle test, the discharged positive electrode was powdered using CuKα1 rays. When analyzed by X-ray diffraction, a peak was observed in the range where 2θ is between 18.7° and 19.0°. Its full width at half maximum is 0.10° or less, more preferably 0.08° or less, and 2θ is 45.0°. A peak occurs in the range of 45.3° or less, and its full width at half maximum is preferably 0.12° or less. The temperature is 0.09° or less. The charge-discharge cycle test at this time is performed up to a voltage of 4.7V with a current value The current is charged at 0.5C (while satisfying 1C = 200mA / g), and then the current... After constant voltage charging until the value reaches 0.05C, pause for 10 minutes, and then charge the current until the voltage reaches 2.5V. After discharging at a constant current of 0.5C, repeat the charge-discharge cycle of 100 times, followed by a 10-minute rest period. It shall be considered as such.

[0080] Because it can withstand charge-discharge cycle tests with high cutoff voltages, the positive electrode activity of one aspect of the present invention By using materials, it is possible to realize positive electrodes with high energy density, and even secondary batteries. If the volume energy density calculated using the true density of the positive electrode active material is 4250 Wh / L or higher, The gravimetric energy density calculated using the true density of the positive electrode active material is 865 Wh / kg or higher. It is possible.

[0081] ≪Calculation≫ First-principles calculations were performed to obtain evidence of a mechanism that blocks the transition to the H1-3 phase. Ta.

[0082] When the oxygen stack is in the O3 phase and when it is in the H1-3 phase, one lithium A model was created in which all lithium was removed from the layer. Models with one magnesium atom added also include O3-phase stacking and H1-3-phase stacking. These models were created by performing structural optimization, including cell size, and energy —we compared them.

[0083] The calculation is performed using a density functional method (PAW) that implements the PAW method. The calculation was performed using the software "VASP" (Theory). The calculation included the cell size. We performed optimization of the design. Exchange-correlation interaction was analyzed using GGA-PBE. The degrees of freedom of spin were considered. I didn't consider it. To correct for dispersion interactions, Becke-Johnson dampin The DFT-D3(BJ) method using the g function was employed. Cutoff energy - was set to 1000 eV, and k-point sampling was 3x3x3. In the electronic state calculation, energy Change is 10 -8 Convergence was considered to have occurred when the value became smaller than eV. Also, in structural optimization... Structural relaxation stopped when all forces fell below 0.001 eV / Å.

[0084] The computational model assumes that the CoO2 layer in LiCoO2 is O3-phase stacked. There are two models: the O3-phase stacking model and the H1-3 phase stacking model (H1- The three-phase stacking model was used as the basic model. These two basic models were used in the calculations. The cell used has a layered structure consisting of a Li layer, a CoO2 layer, a Li layer, and a CoO2 layer. The number of atoms is 24 for Li, 24 for Co, and 48 for O. Then, all the Li present in one Li layer is eliminated, and the 12 Li in the other Li layer are removed. A model was created that retained only 4 of them. These two models are the Mg-free models. These Mg-free models are then modified by adding one Mg atom to the layer where all Li has been removed. We will use the model with Mg. Ultimately, we will use the "Mg-free O3 phase stacking model" and the "Mg-free H "1-3 phase stacking model", "O3 phase stacking model with Mg", "H1- with Mg" We created four models of the "3-phase stacking model".

[0085] For these four models, we performed structural optimization, including cell size, and compared the energy. We compared the "Mg-containing O3 phase stacking model" and the "M The "g-containing H1-3 phase stacking model" is shown in Figures 7(A) and 7(B). Also, 4 The energies of the two models are shown in Table 1. Here, E(H1-3) and E(O3) are respectively This represents the energy of the H1-3 phase stacking and O3 phase stacking models.

[0086] [Table 1]

[0087] Without magnesium, the H1-3 phase stacking model has lower energy, but magnesium With nesium present, the O3-phase stacking model has lower energy. The results suggest that the presence of magnesium makes it more difficult for H1-3 layers to form. In the O3-phase stacking model containing magnesium, cobalt is positioned above and below the magnesium. Although it does not exist in the H1-3 phase stacking model, cobalt exists above and below magnesium. This is due to electrostatic repulsion between magnesium and the cobalt above and below it, which causes the magnesium-containing H The energy of the 1-3 phase stacking model is thought to have increased. Furthermore, magnesium This is thought to increase the energy barrier when the CoO2 layer shifts.

[0088] This calculation shows that magnesium acts as a pillar, causing a phase change to the H1-3 phase. This suggests that it may hinder [something].

[0089] ≪Li's Ordering≫ For example, by performing ex situ XRD measurements, the cobalt in the O3' phase can be determined as described above. The coordinates of oxygen can be determined. On the other hand, since lithium has low X-ray scattering ability, XRD cannot analyze whether the lithium in the O3’ phase is ordered or irregular. For example, Fig. 8(A) is a view of the crystal structure model of the O3’ phase from the a-axis direction, and Fig. 8(B) is a view from the c-axis direction. These are figures based on the assumption that lithium exists at the same probability in all lithium sites.

[0090] However, in reality, lithium in the O3’ phase may be ordered, and it may be possible to determine the lithium arrangement by structural analysis using other techniques such as neutron diffraction. When the lithium in the O3’ phase is ordered, examples of x and lithium arrangements in Li CoO2 will be described using Figs. 8(D) to 12. These are all views of the crystal structure model of the O3’ phase from the c-axis direction. In Figs. 8(D) to 10 and Fig. 1 2, for clarity, lithium sites are represented by the vertices of an equilateral triangle, and lithium is represented by a hatched circle. For reference, Fig. 8(C) shows an overlay of the same figure as Fig. 8(B) and a figure representing lithium sites by the vertices of an equilateral triangle. x CoO2 Figs. 8(D) to 12 are used to explain examples of lithium arrangements in a certain lithium layer of the O3’ phase when it is Li CoO2. These are all views of the crystal structure model of the O3’ phase from the c-axis direction. In Figs. 8(D) to 10 and Fig. 1 2, for clarity, lithium sites are represented by the vertices of an equilateral triangle, and lithium is represented by a hatched circle. For reference, Fig. 8(C) shows an overlay of the same figure as Fig. 8(B) and a figure representing lithium sites by the vertices of an equilateral triangle. CoO2

[0091] Fig. 8(D) shows an example of the lithium arrangement in a certain lithium layer of the O3’ phase when it is Li 1 / 3 CoO2. In the following figures, the hatched parallelogram represents the minimum repeating unit. CoO2. In the following figures, the hatched parallelogram represents the minimum repeating unit.

[0092] Fig. 8(E) shows an example of the lithium arrangement in a certain lithium layer of the O3’ phase when it is Li 1 / 4 CoO2. CoO2.

[0093] ​​​ Figure 9(A) shows that the O3' phase is Li 2 / 9 One possible scenario in the case of CoO2 is a certain layer An example of lithium arrangement in a lithium layer is shown.

[0094] Figures 9(B) to 9(E) show that the O3' phase is Li 1 / 6 Possible scenarios when CoO2 is involved. This shows an example of a lithium arrangement in a single lithium layer.

[0095] Figure 10 shows that the O3' phase is Li 1 / 4 A possible sequence of three layers in the case of CoO2 An example of lithium arrangement in the lithium layer is shown. To make the figure clearer, the vertices are lithium The equilateral triangles representing the threads are drawn with solid lines in the first layer, dotted lines in the second layer, and thin solid lines in the third layer, and the same threads The lithium present in the thium layer was given the same hatching. Figure 10 shows Figure 8(E) in three layers. This can also be described as a superimposed view from the c-axis direction.

[0096] Figures 11(A) to 11(C) show that the O3' phase is Li 1 / 6 Consider the case where it is CoO2. An example of a lithium arrangement in a set of three consecutive lithium layers is shown. To distinguish between different lithium atoms, lithium atoms within the same lithium layer were connected by lines. Figure 1 Figures 1(A) through 11(C) can be considered three examples of the case where Figure 9(D) is superimposed three times.

[0097] In Figures 10 to 11(C), lithium is present in all lithium layers of the O3' phase. I have explained an example, but this is not the only possible lithium arrangement. It is also possible that layers with and without lithium appear alternately in between.

[0098] Figure 12 shows that the O3' phase is Li 1 / 8Examples of lithium arrangements in a certain continuous four-layer of lithium layers that can be considered when it is CoO2 are shown. The first layer is drawn as a solid line, the second layer as a dotted line, the third layer as a thin solid line, and the fourth layer as a dotted line. Figure 12 shows an example where the first and third layers have lithium in the same arrangement as in Figure 8(E), and the second and fourth layers have no lithium. Regarding both the arrangement within the lithium layer plane and the arrangement in the c-axis direction, the lithium arrangement is not limited to the above. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. Also, it is assumed that the positive electrode active material does not contain an electrolyte, an organic solvent, a binder, a conductive material, or a compound derived therefrom attached to the positive electrode active material.

[0099] Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate.

[0100] In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate.

[0101] In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate. In addition, in this specification and the like, the surface of the positive electrode active material shall refer to the surface of lithium cobaltate doped with magnesium or the like. Therefore, the positive electrode active material of one aspect of the present invention is one to which a metal oxide having no lithium sites that can contribute to charge and discharge, such as aluminum oxide (Al2O3), is attached, and does not include carbonate, hydroxide groups, etc. chemically adsorbed after the production of the positive electrode active material. The attached metal oxide refers to, for example, a metal oxide whose crystal structure does not match that of lithium cobaltate.

[0102] Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. Since the positive electrode active material of one aspect of the present invention is a compound having a transition metal and oxygen capable of inserting and extracting lithium, the interface between the region where cobalt and oxygen that are oxidized and reduced with the insertion and extraction of lithium exist and the region where they do not exist is defined as the surface of the positive electrode active material. A surface generated by a slip, a closed crack, or a crack may also be referred to as the surface of the positive electrode active material. When analyzing the positive electrode active material, a protective film may be attached to the surface, but the protective film is not included in the positive electrode active material. As a protective film, a single-layer or multi-layer film of carbon, metal, oxide, resin, etc. may be used. There is.

[0103] Therefore, the position of the surface of the positive electrode active material in STEM-EDX radiation analysis, etc., is the position of cobalt. The amount of characteristic X-rays detected is the average value of the amount of characteristic X-rays detected from the internal cobalt. AVE And, back Average value of the detected cobalt characteristic X-rays in the ground (Co BG The point that is 50% of the sum of the two, The amount of oxygen characteristic X-rays detected is the average value of the amount of oxygen characteristic X-rays detected inside. AVE And, Average value of the oxygen characteristic X-ray detection amount in Kuground O BG Let this be the point where the sum of the two is 50%. Furthermore, the amount of cobalt characteristic X-rays detected is the average value of the amount of cobalt characteristic X-rays detected inside the body. The point is that it is 50% of the average sum of the detected amounts of cobalt characteristic X-rays in Kugland, and the characteristic of oxygen The amount of characteristic X-rays detected is the average value of the amount of characteristic X-rays detected in the internal oxygen and the characteristic of the background oxygen. If the point where the sum of the average values ​​of the detected X-rays is 50% is different, then oxygen adhering to the surface This is thought to be due to the influence of metal oxides, carbonates, etc., and therefore the amount of cobalt characteristic X-rays detected is within The average value of the detected amount of characteristic X-rays of cobalt in the area. AVE And the cobalt background Average value of the detected characteristic X-ray Co BG The point where the sum of the two values ​​is 50% is the position on the surface of the positive electrode active material. They can be hired.

[0104] Average value of the detected characteristic X-rays of background cobalt Co BG For example, cobalt Avoid the area where the detection amount of characteristic X-rays begins to increase, and instead use an outer 2 nm or more, preferably 3 nm or less. The above range can be averaged to obtain the result. Also, the average of the detected amount of characteristic X-rays of the internal cobalt. Value Co AVE This is a region where the detection amount of characteristic X-rays for cobalt and oxygen is saturated and stable, for example, co From the region where the amount of Balt's characteristic X-rays detected begins to increase, the depth is 30 nm or more, preferably 50 nm. In the portion exceeding m, the average can be calculated for a range of 2 nm or more, preferably 3 nm or more. It can be done. The average value of the detected characteristic X-rays of background oxygen. BG and the properties of oxygen inside Average value of X-ray detection amount O AVE This can be calculated in a similar manner.

[0105] To increase the spatial resolution in STEM-EDX radiation analysis, the electron beam... A small diameter (also called beam diameter, probe diameter, or probe diameter) is preferable. In TEM-EDX radiation analysis, the beam diameter is preferably 0.3 nm or less. It is more preferably 0.2 nm or less, and even more preferably 0.1 nm or less. .

[0106] Furthermore, the surface of the positive electrode active material in cross-sectional STEM (scanning transmission electron microscope) images, etc., is the positive electrode. The boundary between the region where an image originating from the crystal structure of the active material is observed and the region where it is not observed. Among the metal elements that make up the positive electrode active material, the nuclei of metal elements with an atomic number greater than lithium This refers to the outermost region where the originating atomic column can be identified, or the region from the surface of the STEM image. This point is defined as the intersection of the tangent line drawn to the luminance profile toward the bulk and the axis in the depth direction. Surfaces in EM images and similar images may be judged in conjunction with analyses that have higher spatial resolution.

[0107] Furthermore, the spatial resolution of STEM-EDX is approximately 1 nm. Therefore, the doped element profile The maximum value of the il can be off by about 1 nm. For example, outside the surface determined above. Even if there is a maximum value for the alloying element profile such as magnesium, the difference between the maximum value and the surface is 1 nm. If it is less than the specified value, it can be considered an error.

[0108] Furthermore, in STEM-EDX radiation analysis, the peaks refer to the detection intensity in each element's profile. This refers to the maximum value in degrees, or the maximum value of characteristic X-rays for each element. Noise in line analysis includes the full width at half maximum (FMAX) which is less than or equal to the spatial resolution (R), for example, R / 2. Measurement values ​​are a possible explanation.

[0109] Scanning the same area multiple times under the same conditions can reduce the effects of noise. For example, The cumulative values ​​measured over 6 scans can be used to create a profile for each element. The number of scans is It's not limited to 6; you can do more and use the average as the profile for each element.

[0110] STEM-EDX radiation analysis can be performed, for example, as follows: First, the positive electrode active material A protective film is deposited on the surface. For example, an ion sputtering apparatus (Hitachi High-Tech MC1000) Carbon can be deposited using this method.

[0111] Next, the positive electrode active material is thinned to prepare a STEM cross-sectional sample. For example, using a FIB-SEM device. Thinning can be performed using the Hitachi High-Tech XVision200TBS. During this process, the pickup is performed using an MPS (Micro Probing System), and the finishing conditions are as follows: For example, the acceleration voltage can be set to 10kV.

[0112] STEM-EDX radiation analysis is performed using, for example, a STEM instrument (Hitachi High-Tech HD-2700). Using this, the EDX detector is the EDAX Octane T Ultra W (double-inserted). This can be used. During EDX radiation analysis, the emission current of the STEM instrument should be 6 μA. Set the current to 10 μA or less, and select the area with less depth and unevenness from the thinned sample. The measurement is taken. The magnification is, for example, about 150,000 times. The conditions for EDX line analysis are drift correction. Positive feedback is possible, with a line width of 42 nm, a pitch of 0.2 nm, and 6 or more frames.

[0113] Furthermore, when magnesium and nickel are present together in the surface layer, the vicinity of divalent magnesium In this state, divalent nickel may be able to exist more stably. Therefore, a high delithium state However, magnesium leaching may be suppressed. Therefore, it may contribute to the stabilization of the surface layer.

[0114] For similar reasons, when adding additive elements to lithium cobalt oxide during the manufacturing process, magnesium Nesium is preferably added in a step before nickel, or with magnesium. Nickel is preferably added in the same process. Magnesium has a large ionic radius. Regardless of the process in which it is added, lithium cobalt oxide tends to remain on the surface layer, whereas nickel In the absence of magnesium, it can diffuse widely into the interior of lithium cobaltate. When nickel is added before magnesium, the nickel enters the interior of lithium cobalt oxide. There is a concern that it will disperse and not remain in a desirable amount on the surface.

[0115] Furthermore, the presence of additive elements with different distributions in the depth direction allows for a more stable crystal structure over a wider region. It is preferable that it can be stabilized. For example, the positive electrode active material of one aspect of the present invention has magnesium in the surface layer. The maximum values ​​of the detected amounts of aluminum and nickel, and the maximum values ​​of the detected amount of aluminum, in the depth direction. It is preferable that they differ. Also, the maximum values ​​of magnesium and nickel detected are Therefore, it is preferable that the maximum amount of aluminum detected is located inside the particle.

[0116] Having this kind of distribution of additive elements allows for the stabilization of the crystal structure over a wider range. In cases where magnesium and nickel are present together with aluminum, the table Since the stabilization of the layers can be adequately achieved by magnesium and nickel, aluminum is used on the surface. It is not essential for aluminum to be present on the surface. Rather, it is preferable for aluminum to be widely distributed in deeper regions. For example, aluminum can be continuously detected in the region from the surface to a depth of 1 nm to 25 nm. It is preferable that it be released. A region from the surface to a region of 0 nm or more and 100 nm or less, preferably from the surface A wider distribution within the region between 0.5 nm and 50 nm is preferable for maintaining a stable crystal structure over a wider area. It is preferable that it can be standardized.

[0117] As described above, when multiple additive elements are present, the effects of each additive element synergistically affect the surface layer. This could contribute to further stabilization.

[0118] Furthermore, the additive elements, namely magnesium, fluorine, nickel, and aluminum, are used in the positive electrode. It is preferable that the active material is solid-dissolved. For example, line analysis by STEM-EDX is performed. When this occurs, the depth at which the amount of additive elements detected increases is the depth at which the amount of cobalt detected increases. It is preferable that the position is deeper than the depth, i.e., located on the interior side of the positive electrode active material.

[0119] Furthermore, in this specification, the amount of an element detected in STEM-EDX line analysis is defined as follows: The depth at which the value increases refers to the measured value that can be judged as not being noise in terms of intensity and spatial resolution, etc. However, this refers to the depth to which a continuous result can be obtained.

[0120] This embodiment can be appropriately combined with the contents of other embodiments.

[0121] (Embodiment 2) This embodiment describes the configuration of a lithium-ion battery.

[0122] [Positive electrode] The positive electrode has a positive electrode active material layer and a positive electrode current collector. The positive electrode active material layer has a positive electrode active material, Furthermore, it may have at least one of a conductive additive and a binder. The positive electrode active material is the same as in the previous embodiment. You can use the form described above.

[0123] Figure 13(A) shows an example of a schematic diagram of the cross-section of the positive electrode.

[0124] The current collector 550 can be made of, for example, metal foil. The positive electrode is made of a slurry on the metal foil. It can be formed by applying and drying. After drying, press is applied. This is also acceptable. The positive electrode has an active material layer formed on the current collector 550.

[0125] Slurry is a liquid material used to form an active material layer on the current collector 550. This refers to a mixture containing a substance, a binder, and a solvent, preferably further containing a conductive additive. Furthermore, slurry is sometimes called electrode slurry or active material slurry, and is used for positive electrodes. When forming the active material layer, use the slurry for the positive electrode, and when forming the negative electrode active material layer, use the slurry for the negative electrode. It is sometimes called an extreme slurry.

[0126] The positive electrode active material 561 takes in and / or releases lithium ions during charging and discharging. It has the function of having a high charging voltage. The positive electrode active material 561 used in one aspect of the present invention has the function of having a high charging voltage. Even if the material does not degrade significantly with charging and discharging, it is possible to use such a material. Unless otherwise specified, the charging voltage shall be expressed relative to the potential of lithium metal. In this specification, a high charging voltage is, for example, a charging voltage of 4.6V or higher, and is preferred. The voltage should be 4.65V or higher, more preferably 4.7V or higher, and even more preferably 4.75V. In summary, the most preferable voltage is 4.8V or higher.

[0127] The positive electrode active material 561 used in one aspect of the present invention is characterized by high charging voltage and the effects of charging and discharging. Any material that does not degrade easily can be used, as described in Embodiment 1. This can be used. Furthermore, the positive electrode active material 561 is also associated with charging and discharging at high charging voltages. If the materials are resistant to degradation, two or more materials with different particle sizes can be used.

[0128] Conductive additives, also called conductive imparters or conductive materials, can use carbon materials. By attaching a conductive additive between the active materials, multiple active materials are electrically connected to each other, resulting in conductivity. The effect increases. In this specification, "adhesion" means that the active material and the conductive additive are physically in close contact. This does not only refer to the fact that a covalent bond is formed, but also to the van der Waals force when a covalent bond is formed. When bonding occurs, if a portion of the surface of the active material is covered by the conductive additive, the conductive additive will be carried along the surface irregularities of the active material. This includes cases where the electro-aiding agent is embedded, or where it is electrically connected even if it is not in direct contact with the other components. I will keep that in mind.

[0129] Specific examples of carbon materials that can be used as conductive additives include carbon black (Farne). Examples include black, acetylene black, and graphite.

[0130] Figure 13(A) illustrates carbon black 553 as a conductive additive.

[0131] As the positive electrode of a lithium-ion battery, a current collector 550 such as metal foil and an active material are fixed together. To achieve this, a binder (resin) may be mixed in. A binder is also called a binding agent. The binder is a polymer material, and if a large amount of binder is included, the proportion of active material in the positive electrode decreases. This reduces the discharge capacity of the lithium-ion battery. Therefore, the amount of binder should be kept to a minimum. It is preferable to combine them. In Figure 13(A), the positive electrode active material 561 and the second active material 56 2. Areas not filled with carbon black 553 indicate voids or binder. .

[0132] Note that Figure 13(A) shows an example in which the positive electrode active material 561 is depicted as spherical, but It is not limited to these. For example, the cross-sectional shape of the positive electrode active material 561 may be elliptical, rectangular, trapezoidal, or conical. The polygon may have rounded corners or be asymmetrical. For example, in Figure 13(B), the positive electrode is This shows an example of material 561 having a polygonal shape with rounded corners.

[0133] Furthermore, in the positive electrode of Figure 13(B), the carbon material used as a conductive additive is graphite. Figure 13(B) shows a positive electrode active material 561 and graphite on the current collector 550. A positive electrode active material layer containing 554 and carbon black 553 is formed.

[0134] Furthermore, the process involves mixing graphene 554 and carbon black 553 to obtain an electrode slurry. In this case, the weight of the carbon black to be mixed should be between 1.5 and 20 times the weight of the graphene. It is preferable that the weight be between 2 and 9.5 times the original weight.

[0135] Furthermore, if the mixture of graphene 554 and carbon black 553 is defined as the above range, then the slurry - During preparation, carbon black 553 exhibits excellent dispersion stability, making it less prone to aggregation. If the above range is defined as a mixture of graphene 554 and carbon black 553, then carbon black A higher electrode density can be achieved than in a positive electrode using only KU553 as a conductive additive. Electrode density By increasing the weight, the volume per unit weight can be increased. Specifically, The density of the positive electrode active material layer, as measured, can be 3.5 g / cc or higher.

[0136] Furthermore, compared to a positive electrode that uses only graphene as a conductive additive, the electrode density is lower, but the first carbon The above range is defined as a mixture of the primary material (graphene) and the second carbon material (acetylene black). This enables rapid charging. Therefore, as a lithium-ion battery for use in vehicles It is particularly effective when used in this way.

[0137] Figure 13(C) illustrates an example of a cathode using carbon fiber 555 instead of graphene. Figure 13(C) shows a different example from Figure 13(B). When carbon fiber 555 is used... This prevents the aggregation of carbon black 553 and improves its dispersibility.

[0138] In Figure 13(C), the positive electrode active material 561, carbon fiber 555, and carbon black are shown. Areas not filled with 553 indicate voids or binders.

[0139] Furthermore, Figure 13(D) illustrates another example of a positive electrode. In Figure 13(C), the graph... This example shows the use of carbon fiber 555 in addition to graphene 554. Graphene 554 and carbon Using both fibers 555 prevents the aggregation of carbon black such as carbon black 553. It can prevent and further improve dispersion.

[0140] Note that in Figure 13(D), the positive electrode active material 561, carbon fiber 555, and graphene 554 are shown. Areas not filled with carbon black 553 indicate voids or binder.

[0141] Use one of the positive electrodes shown in Figures 13(A) to 13(D), and place a separator on top of the positive electrode. The laminate, in which the negative electrode is stacked on top of the separator, is placed in a container (outer shell, metal can, etc.) that houses the laminate. Lithium-ion batteries are manufactured by filling a container with a liquid electrolyte (also called electrolyte solution). It is possible.

[0142] <Binder> Examples of binders include styrene-butadiene rubber (SBR) and styrene-isopropyl alcohol. Lenyl-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer as a binder. Therefore, fluororubber can be used.

[0143] <Positive electrode current collector> Current collectors include metals such as stainless steel, gold, platinum, aluminum, and titanium, and these Highly conductive materials such as alloys can be used. Furthermore, the material used for the positive electrode current collector is It is preferable that the material does not dissolve at the positive electrode potential. Also, silicon, titanium, neodymium, and Scandinavian are preferable. Aluminum alloys to which elements that improve heat resistance, such as um and molybdenum, are added are used. It can also be formed with a metallic element that reacts with silicon to form a silicide. Examples of metallic elements that react with silicon to form silicides include zirconium and titanium. Hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, corn Examples include Baltic and nickel. Current collectors come in foil, plate, sheet, mesh, and perforated metal forms. Shapes such as expanded metal or other shapes can be used as appropriate. The current collector has a thickness of 5 μm. It is best to use materials with a size of 30 μm or less.

[0144] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. The negative electrode active material layer also has a negative electrode active material. Furthermore, it may also contain a conductive additive and a binder.

[0145] <Negative electrode active material> For example, alloy materials and / or carbon materials can be used as the negative electrode active material.

[0146] Carbon materials used in the negative electrode active material include graphite, easily graphitizable carbon (soft carbon), and poorly graphitizable carbon. Hard carbon, carbon fiber (carbon nanotubes), graphene, carbon You may use one or more selected from black, etc.

[0147] Graphite can be artificial graphite or natural graphite. Examples of artificial graphite include mesocar. Examples include Bonn microbeads (MCMB), coke-based synthetic graphite, and pitch-based synthetic graphite. Here, spheroidal graphite, which has a spherical shape, can be used as artificial graphite. MCMB may have a spherical shape, which is preferable. Also, the surface area of ​​MCMB is It is relatively easy to reduce the size, which is sometimes preferable. Examples of natural graphite include, Examples include flaky graphite and spheroidized natural graphite.

[0148] Graphite is formed when lithium ions are inserted into it (during the formation of lithium-graphite intercalation compounds). ) exhibits a potential as low as lithium metal (0.05V to 0.3V vs. Li + (Li). As a result, lithium-ion batteries using graphite exhibit a high operating voltage. Yes, it is possible. Furthermore, graphite has a relatively high volume per unit volume and relatively small volume expansion. It is preferable because it has advantages such as being inexpensive and having higher safety compared to lithium metal.

[0149] Furthermore, the negative electrode active material undergoes charge and discharge reactions through alloying and dealloying reactions with lithium. Elements that can be used include silicon, tin, gallium, and aluminum. From germanium, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. One or more selected materials can be used. Such elements have a capacity compared to carbon. The capacity is large, and silicon in particular has a high theoretical capacity of 4200 mAh / g. Also, these elements Compounds containing the following properties may be used. For example, SiO, Mg2Si, Mg2Ge, SnO, Sn O2, Mg2Sn, SnS2, V2Sn3, FeSn2, CoSn2, Ni3Sn2, C u6Sn5, Ag3Sn, Ag3Sb, Ni2MnSb, CeSb3, LaSn3, La Examples include 3Co2Sn7, CoSb3, InSb, SbSn, etc. Here, alloys with lithium... Elements capable of undergoing charge-discharge reactions by alloying and dealloying reactions, and compounds having such elements. These are sometimes referred to as alloy materials.

[0150] In this specification, "SiO" refers to, for example, silicon monoxide. Alternatively, SiO is, SiOx It can also be expressed as follows. Here, it is preferable that x has a value of 1 or one neighboring value. For example, x is preferably between 0.2 and 1.5, and preferably between 0.3 and 1.2.

[0151] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4) are used as negative electrode active materials. Ti5O 12 ), lithium-graphite intercalation compound (Li x C6), niobium pentoxide (Nb2O5) ), one or two selected from tungsten oxide (WO2), molybdenum oxide (MoO2), etc. The above oxides can be used.

[0152] Furthermore, as the negative electrode active material, a Li3N type structure, which is a lithium and transition metal binitride, is also used. TsuLi 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2. 6Co 0.4 N3 has a large discharge capacity (900mAh / g, 1890mAh / cm²). 3 ) indicates And it is preferable.

[0153] When using a lithium-transition metal binitride, lithium ions are included in the negative electrode active material. In combination with materials such as V2O5 and Cr3O8 that do not contain lithium ions as the positive electrode active material. It is preferable that this be done. Furthermore, when using a material containing lithium ions as the positive electrode active material, Also, by pre-desorbing the lithium ions contained in the positive electrode active material, the negative electrode active material and Therefore, a lithium-transition metal composite can be used.

[0154] Furthermore, materials that undergo a conversion reaction can also be used as the negative electrode active material. For example For example, lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO). Transition metal oxides that do not form alloys with mu may be used as the negative electrode active material. Conversion reaction Materials that produce this include Fe2O3, CuO, Cu2O, RuO2, and Cr2O3. Oxides such as CoS 0.89 , sulfides such as NiS and CuS, Zn3N2, Cu3N, Ge Nitrides such as 3N4, phosphides such as NiP2, FeP2, CoP3, FeF3, BiF3, etc. This also occurs with fluorides.

[0155] Furthermore, multiple negative electrode active materials may be used in combination, for example, graphite and silicon particles. A negative electrode active material mixed with silicon particles may also be used. Silicon particles are used in the negative electrode of lithium-ion secondary batteries. Silicon powder as a material for the highly active substance, and the average particle size of the particle size distribution, i.e., the average particle diameter This refers to particles around 100 nm in size, and is sometimes called nanosilicon particles. It is preferable to grind the silicon raw material and adjust the particle size to a uniform size. The child may contain at least one of silicon, silicon oxide, or silicon alloy. In addition, particle size can typically be measured using laser diffraction particle size distribution measurement. However, this is not limited to laser diffraction particle size distribution measurement, but also includes SEM (scanning electron microscope) or TE (transistor spectroscopy). M (Transmission Electron Microscope) The major axis of the particle cross-section may be measured by analysis such as microscopy.

[0156] Furthermore, the conductive additives and binders that the negative electrode active material layer may have include positive electrode active material The same materials as the conductive additive and binder that the layer can possess can be used.

[0157] <Negative electrode current collector> In addition to the same materials as the positive electrode current collector, copper and other materials can also be used for the negative electrode current collector. It is preferable to use a material that does not alloy with carrier ions such as lithium for the negative electrode current collector. .

[0158] [Electrolyte] The electrolyte contains an organic solvent, but the organic solvent is not limited to being a liquid at 25°C. It may be a solid at °C or a semi-solid at room temperature. Note that organic solvents can be used from below freezing to high temperatures. It is preferable, but not limited to, that the organic solvent be liquid over a wide temperature range. It is a liquid, solid, or semi-solid in a wide temperature range including below freezing and high temperatures. That's fine.

[0159] As the organic solvent, an aprotic organic solvent is preferred, for example, ethylene carbonate. (EC), Propylene Carbonate (PC), Butylene Carbonate, Chloroethylene Carbonate - Carbonate, vinylene carbonate, γ-butyrolactone, γ-valerolactone, dimethyl Diethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), 1,3-propanesultone (PS), fluoroethylene carbonate (F EC), methyl 3,3,3-trifluoropropionate (MTFP), methyl formate, vinegar Methyl acid, ethyl acetate, methyl propionate, ethyl propionate, propionate Methyl butyrate, 1,3-dioxane, 1,4-dioxane, dimethoxyethane (DME ), dimethyl sulfoxide, diethyl ether, methyl diglyme, acetonitrile, One of the following: zonitrile, tetrahydrofuran, sulfolane, sultone, or one of these. Two or more of these can be used in any combination and ratio.

[0160] PS is equivalent to EC and DEC in HOMO (Highest Occupied Mass olecular Orbital), LUMO(Lowest Unoccupied Because it has a Molecular Orbital (Molecular Orbital) level, even at high cutoff voltages It is resistant to oxidation and reduction, and when it decomposes on the surface of the positive electrode active material, it tends to form polymers. Therefore, it has the advantage of being less likely to decompose into gaseous products with small molecular weights. Therefore, the electrolyte preferably contains 0.1 wt% to 10 wt% of PS, and 0. It is more preferable to have 25 wt% to 7.5 wt%.

[0161] FEC is a type of cyclic carbonate with a high dielectric constant, and is used in organic solvents. In its presence, it has the effect of promoting the dissociation of lithium salts. On the other hand, FEC exhibits electron-withdrawing properties. Because it has substituents, desolvation with lithium ions proceeds more easily than with EC. Specifically, FEC is a lithium ion solvation energy that does not have substituents that exhibit electron-withdrawing properties. It is smaller than that. Therefore, lithium ions are present on the positive electrode active material surface and the negative electrode active material surface. This makes it easier to separate the components and lowers the internal resistance of the secondary battery. Furthermore, FEC has a deep HOMO level. Therefore, it is less prone to oxidation and has improved oxidation resistance. On the other hand, the high viscosity of FEC is a concern. Therefore, if a mixed organic solvent containing not only FEC but also MTFP is used as the electrolyte... Good. MTFP is a type of linear carbonate that reduces the viscosity of electrolytes or lowers the viscosity at low temperatures. It has the effect of maintaining the viscosity at room temperature (typically 25°C) even at (typically 0°C). This is also possible. Furthermore, MTFP is methyl propionate without substituents that exhibit electron-withdrawing properties. Although it has a lower solvation energy than Lu (abbreviated as "MP"), when used in an electrolyte... It may also produce solvation with lithium ions. It contains both FEC and MTFP. When using a mixed organic solvent, if the volume ratio is FEC:MTFP = 1:y, then 2 ≤ y ≤ 20 is preferred, and 4 ≤ y ≤ 9 is more preferred.

[0162] The organic solvents mentioned above contain particulate matter or molecules other than the constituent molecules of the organic solvent (hereinafter simply Also called "impurities," these contain oxygen (O2), water (H2O), or moisture. It is preferable that the product is not present and is highly purified. Furthermore, it is preferable that the reaction byproducts from the synthesis are not produced after appropriate purification. It is preferable that the substance is suppressed. Specifically, the impurity concentration of the electrolyte should be 100 ppm or less. Preferably, the concentration should be 50 ppm or less, and more preferably less than 10 ppm. Among the impurities, water is the most important. The concentration can be detected by Karl Fischer titration.

[0163] Furthermore, the aforementioned organic solvents showed almost no peaks attributable to impurities through NMR measurements, etc. It is preferable that it is not possible. "Almost impossible to confirm" means that the integral area of ​​the peak caused by the principal component is not considered. Furthermore, the ratio of the integral area of ​​the peaks caused by impurities (simply called the integral ratio) is 0.005 or less. This includes values ​​of 0.002 or less. The apparatus used for NMR measurement is not particularly limited. However, for example, you can use Bruker's "AVANCE III 400 model". Furthermore, in 1H-NMR measurements, the acetonitrile-d3 derived from the solvent... Of the five peaks in the rill, the central peak can be set to 1.94 ppm.

[0164] For example, in the case of MTFP, ¹H-NMR was measured using acetonitrile-d3 solvent. In this case, it is known that four peaks appear when δ is between 3.29 ppm and 3.43 ppm. However, if other peaks occur in the vicinity, for example, if δ is 3.24 ppm or higher, If a peak occurs below 0.29 ppm, it is considered to be due to impurities. For peak areas between 3.29 ppm and 3.43 ppm, the peak area between 3.24 ppm and 3.43 ppm The ratio of peak areas (integral ratio) of 0.29 ppm or less is 0.005 or less, preferably 0.00 If the value is 2 or less, it can be said that peaks caused by impurities are almost impossible to detect.

[0165] Furthermore, as the solvent for the electrolyte, an ionic liquid (a room-temperature molten salt) that is flame-retardant and non-volatile is used. Using one or more of these devices can cause the internal temperature of the energy storage device to rise due to internal short circuits or overcharging. Even if this occurs, it can prevent the rupture and ignition of the energy storage device. Ionic liquids are composed of cations and ions. It consists of nions and includes organic cations and anions. As an organic cation used in electrolytes quaternary ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations Aliphatic onium cations such as n, imidazolium cations and pyridinium cations, etc. Aromatic cations are one example. Also, monovalent amide-based anions are used as anions in the electrolyte. Nions, monovalent methide anions, fluorosulfonate anions, perfluoroalkyl Sulfonate anions, tetrafluoroborate anions, perfluoroalkyl borates Anions, hexafluorophosphate anions, or perfluoroalkyl phosphates Examples include anions.

[0166] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, and L. iAsF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO 4. Li2B 10 Cl 10 Li2B 12 Cl 12 LiCF3SO3, LiC4F9S O3, LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2 )2, LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2, Lithium Lithium salts such as umbis(oxalate)borate (Li(C2O4)2, LiBOB) One type, or two or more of these types, can be used in any combination and ratio. .

[0167] The electrolyte used in the energy storage device contains particulate matter or elements other than the constituent elements of the electrolyte (hereinafter referred to as single It is preferable to use a highly purified electrolyte with a low content of impurities (also called "impurities"). Specifically, the weight ratio of impurities to the electrolyte is 1% or less, preferably 0.1% or less. More preferably, it should be 0.01% or less.

[0168] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used.

[0169] Using polymer gel electrolytes enhances safety against leakage and other issues. The pond can be made thinner and lighter.

[0170] Examples of polymers that can be gelled include silicone gel, acrylic gel, and acrylonitrile gel. Polyethylene oxide gel, polypropylene oxide gel, fluorine polymer Gels such as polyethylene oxide (PEO) can be used. Polymers having a chilenoxide structure, PVDF, and polyacrylonitrile, and the Copolymers containing these can be used. For example, PVDF and hexafluoropropylene PVDF-HFP, a copolymer of (HFP), can be used. The polymer may have a porous structure.

[0171] In addition, a solid electrolyte containing inorganic materials such as sulfide-based or oxide-based materials can be used instead of an electrolyte solution. Alternatively, a solid electrolyte containing polymer materials such as PEO (polyethylene oxide) is used. This is possible. When using a solid electrolyte, the installation of a separator or spacer is unnecessary. It becomes possible to solidify the entire battery, eliminating the risk of leakage and dramatically improving safety. To rise.

[0172] [Separator] When the electrolyte includes a liquid electrolyte, a separator is placed between the positive and negative electrodes. Examples of materials include cellulose-containing fibers such as paper, nonwoven fabrics, and glass fibers. Ceramics, or nylon (polyamide), vinylon (polyvinyl alcohol-based fiber) ), polypropylene (indicated as PP), polyimide (indicated as PI), polyester, acrylic It is possible to use synthetic fibers made of materials such as polyolefins and polyurethane. Yes, it is possible. The separator should have a film thickness with a porosity of 35% to 90%, preferably 60% to 85%. It can be less than %. Separators using polypropylene have a void ratio of 35% or more. It can be 5% or less. Separators using polyimide have a porosity of 75% or more and 85% or less. It can be less than %. The separator film thickness is preferably 10 μm or more and 80 μm or less. A thickness of 20 μm to 60 μm is more preferable. Separators using polyimide have a high porosity. It can have a thick film (typically a film thickness of 50 μm or more and 60 μm or less). It is desirable.

[0173] The separator is processed into a bag shape and positioned to enclose either the positive or negative electrode. It is preferable.

[0174] The separator may have a multilayer structure. For example, an organic material such as polypropylene or polyethylene. The material film contains ceramic materials, fluorine-based materials, polyamide-based materials, or these materials. A mixture of these can be used as a coating. Examples of ceramic materials include, for example, oxide Aluminum particles, silicon oxide particles, etc. can be used. As for fluorine-based materials, For example, PVDF, polytetrafluoroethylene, etc. can be used. Polyamide materials Materials used include, for example, nylon and aramid (meta-aramid, para-aramid). It is possible.

[0175] Using a multilayer separator allows for a thin overall thickness of the separator, even if it is not lithium-ion. To maintain the safety of the pond, the capacity per unit volume of lithium-ion batteries can be increased. It is possible.

[0176] [Exterior] The outer casing of a lithium-ion battery may be made of a metal material such as aluminum, or Resin materials can be used. A film-like outer covering can also be used. Examples of films include polyethylene, polypropylene, polycarbonate, and ionomer. - On a film made of materials such as polyamide, aluminum, stainless steel, copper, nickel, etc. A highly flexible metal thin film is provided, and further, a polyamide-based material is used as the outer surface of the exterior body on the metal thin film. By using a three-layer film with an insulating synthetic resin film such as resin or polyester resin. It is possible.

[0177] This embodiment can be used in combination with other embodiments.

[0178] (Embodiment 3) This embodiment describes examples of lithium-ion battery configurations.

[0179] [Laminated lithium-ion battery] Examples of the configuration of the laminate-type lithium-ion battery 500 are shown in Figures 14(A) and 14. (B) is shown. Figures 14(A) and 14(B) are external views, and the lithium-ion battery 50 0 represents the electrolyte and separator described in the above embodiment (these are not shown in Figure 14), The lithium-ion battery 500 has a negative electrode 506 and a positive electrode 507. It is preferable that the positive electrode 507 has a larger surface area. Furthermore, lithium-ion battery 500 has a negative A negative lead electrode 510 is electrically connected to electrode 506, and a positive lead electrode 507 is electrically connected to It has a positive lead electrode 511. The electrolyte, negative electrode 506, and positive electrode 507 are enclosed in the outer casing 50 9 is housed in the outer casing, and a portion of the negative lead electrode 510 and a portion of the positive lead electrode 511 are housed in the outer casing. It protrudes from 509. A portion of the outer periphery of the outer casing 509 has an adhesive area 508. Figure 1 4(A) The negative lead electrode 510 and the positive lead electrode 511 are on the same side of the outer casing 509. This is an example of a protruding shape, and the adhesive region 508 is at least the side on which each lead electrode protrudes, It is located on two sides adjacent to the side in question. Also, Figure 14(B) shows the negative lead electrode 510 as an outer casing. The side protruding from 509 and the side of the positive lead electrode 511 that protrudes from the outer casing 509 face each other. This is an example of the configuration, where the adhesive region 508 has at least two sides from which each lead electrode protrudes, and It is located on the side sandwiched between the two sides. In Figures 14(A) and 14(B), the adhesive region 5 The edges where 08 is not located should correspond to the edges where the outer casing 509 is folded.

[0180] By using the positive electrode active material of the present invention in a laminate-type lithium-ion battery 500, This allows for the creation of a secondary battery with high capacity, high discharge capacity, and excellent cycle characteristics. .

[0181] [Coin-type lithium-ion battery] An example of a coin-type lithium-ion battery is described below. Figure 15(A) shows a coin-type (single Figure 15(B) is an exploded perspective view of a layered (flattened) lithium-ion battery, and is an external view. Figure 15(C) is a cross-sectional view thereof. Coin-type lithium-ion batteries are mainly used in small electronic devices. Used in devices. In this specification, etc., coin-type lithium-ion battery refers to button-type lithium-ion battery. Includes ion batteries.

[0182] In Figure 15(A), the overlapping of the components (up / down relationship and positional relationship) is shown for clarity. A schematic diagram is provided to illustrate this point. Therefore, Figure 15(A) and Figure 15(B) are in perfect agreement. This is not intended as a corresponding diagram.

[0183] In Figure 15(A), the positive electrode 304, negative electrode 307, spacer 342, and washer 332 are stacked. The diagram shows how the negative electrode can 302 and positive electrode can 301 are sealed. Figure 15(A) shows the above The electrolyte and separator described in the embodiment are not shown. Spacer 342 and washer When crimping the positive electrode can 301 and the negative electrode can 302, the 332 protects the inside or the position inside the can. It is used to fix it in place. The spacer 342, or washer 332, is made of stainless steel. Alternatively, use insulating materials.

[0184] The positive electrode 304 is a laminated structure in which a positive electrode active material layer 306 is formed on a positive electrode current collector 305. ru.

[0185] Figure 15(B) is a perspective view of the completed coin-type lithium-ion battery 300.

[0186] The coin-type lithium-ion battery 300 has a positive electrode casing 301 which also serves as the positive electrode terminal, and a negative electrode terminal. The negative electrode can 302, which also serves as the negative electrode, is insulated and sealed by a gasket 303 made of polypropylene or the like. It may be done. The positive electrode 304 is provided in contact with the positive electrode current collector 305. The positive electrode is formed by the positive electrode active material layer 306. The negative electrode 307 is formed by the negative electrode current collector 308 and The positive electrode can 301 is formed by a negative electrode active material layer 309 provided in contact with the positive electrode 3 04 and the negative electrode can 302 are electrically connected to the negative electrode 307, respectively.

[0187] Furthermore, the positive electrode 304 and negative electrode 307 used in the coin-type lithium-ion battery 300 are Each active material layer only needs to be formed on one side.

[0188] As shown in Figure 15(C), with the positive electrode can 301 at the bottom, the positive electrode 304, negative electrode 307, and negative electrode can are positioned. The 302s are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are compressed via the gasket 303. We manufacture coin-shaped lithium-ion batteries 300.

[0189] By using the positive electrode active material of the present invention in a coin-type lithium-ion battery 300, high capacity Furthermore, it is possible to create a secondary battery with high discharge capacity and excellent cycle characteristics.

[0190] [Cylindrical lithium-ion battery] An example of a cylindrical lithium-ion battery will be explained with reference to Figure 16(A). As shown in Figure 16(A), the lithium-ion battery 616 has a positive electrode cap (battery cover) on its top surface. It has a 601 and a battery can (outer casing) 602 on its side and bottom. These positive electrode cans The top 601 and the battery can (outer casing) 602 are connected by a gasket (insulating packing) 610. It is insulated.

[0191] Figure 16(B) is a schematic diagram showing a cross-section of a cylindrical lithium-ion battery. The cylindrical lithium-ion battery shown in 6(B) has a positive electrode cap (battery cover) 601 on its top surface. It has a battery case (outer case) 602 on its side and bottom. These positive electrode cap and battery The can (outer can) 602 is insulated by the gasket (insulating packing) 610.

[0192] Inside the hollow cylindrical battery can 602, there is a strip-shaped positive electrode 604 and a negative electrode 606 in the electrolyte layer 6 A battery element is provided wound with 05 in between. Although not shown in the diagram, the battery element is center It is wound around the shaft. Battery casing 602 is closed at one end and open at the other. Inside the can 602, the battery element, in which the positive electrode, negative electrode, and separator are wound, is opposite to It is sandwiched between a pair of insulating plates 608 and 609. Furthermore, the battery element is provided. The inside of the battery container 602 is filled with electrolyte (not shown).

[0193] Since the positive and negative electrodes used in cylindrical storage batteries are wound, active material is formed on both sides of the current collector. It is preferable that the height of the cylinder is greater than the diameter of the cylinder. The illustration shows a lithium-ion battery 616 with a larger diameter, but it is not limited to this. The diameter of the cylinder is A lithium-ion battery that is taller than the height of the cylinder may also be used. With such a configuration, for example This allows for miniaturization of lithium-ion batteries.

[0194] The positive terminal (positive current collector lead) 603 is connected to the positive terminal 604, and the negative terminal 606 is connected to the negative terminal The child (negative current collector lead) 607 is connected. Both the positive terminal 603 and the negative terminal 607 are Metal materials such as aluminum can be used. The positive terminal 603 is connected to the safety valve mechanism 61 3. The negative terminals 607 are resistance-welded to the bottom of the battery can 602. Safety valve mechanism 613 This is a PTC element (Positive Temperature Coefficient It is electrically connected to the positive electrode cap 601 via 611. The safety valve mechanism 613 is electrically connected to the positive electrode cap 601. When the internal pressure of the pond rises above a predetermined threshold, the electrical current between the positive electrode cap 601 and the positive electrode 604 This disconnects the connection. Also, the PTC element 611 has resistance when the temperature rises. It is a thermal resistance element that increases resistance, and by limiting the amount of current due to the increase in resistance, it prevents abnormal heat generation. Therefore, the PTC element 611 is made of barium titanate (BaTiO3) ceramic material. Fees and other charges may be used.

[0195] Figure 16(C) shows an example of the energy storage system 615. The energy storage system 615 has multiple lithium It has a lithium-ion battery 616 and is sometimes called a battery pack. The positive electrode of the battery is in contact with the conductor 624 separated by the insulator 625 and is electrically connected. The conductor 624 is electrically connected to the control circuit 620 via the wiring 623. Furthermore, the negative electrode of each lithium-ion battery is connected to the control circuit 620 via wiring 626. It is electrically connected. Control circuit 620 is a protective circuit that prevents overcharging or over-discharging. The following can be applied.

[0196] Figure 16(D) shows an example of the energy storage system 615. The energy storage system 615 has multiple lithium It has a lithium-ion battery 616, and multiple lithium-ion batteries 616 have a conductive plate 628 and a conductive Multiple lithium-ion batteries 616 are sandwiched between the electrical boards 614. The multiple lithium-ion batteries 616 are connected by wiring 627. Multiple lithium-ion batteries 616 are electrically connected to conductive plates 628 and 614. They may be connected in parallel, or in series, or after being connected in parallel They may also be connected in series. Energy storage system having multiple lithium-ion batteries 616 By configuring the Mu615, a large amount of power can be extracted.

[0197] Even if multiple lithium-ion batteries 616 are connected in parallel and then further connected in series, good.

[0198] A temperature control device may be provided between multiple lithium-ion batteries 616. When the ON battery 616 overheats, the temperature control device cools it down, and the lithium-ion battery 6 When 16 gets too cold, it can be heated by the temperature control device. Therefore, the energy storage The performance of the Stem 615 will be less affected by ambient temperature.

[0199] Furthermore, in Figure 16(D), the energy storage system 615 has wiring 621 and It is electrically connected via wiring 622. Wiring 621 is connected via conductive plate 628 to multiple The wiring 622 is connected to the positive electrode of the lithium-ion battery 616 via the conductive plate 614, and multiple lithium Each is electrically connected to the negative electrode of the ion battery 616.

[0200] By using the positive electrode active material of the present invention in a cylindrical lithium-ion battery 616, high capacity, Furthermore, it is possible to create a secondary battery with high discharge capacity and excellent cycle characteristics.

[0201] [Other structural examples of lithium-ion batteries] Examples of lithium-ion battery structures are explained using Figures 17 and 18.

[0202] The lithium-ion battery 913 shown in Figure 17(A) has terminals 951 and terminals inside the housing 930. It has a winding body 950 to which a child 952 is provided. The winding body 950 is electrolytically operated inside the housing 930. It is impregnated with liquid. Terminal 952 is in contact with the housing 930, and terminal 951 is connected to an insulating material. Therefore, it is not in contact with the housing 930. Note that in Figure 17(A), for convenience, housing 93 Although the zeros are shown separately in the diagram, in reality the wound body 950 is covered by the housing 930, and terminal 951 And terminal 952 extends outside the housing 930. The housing 930 is made of a metal material (for example Aluminum or other resin materials can be used.

[0203] Furthermore, as shown in Figure 17(B), the housing 930 shown in Figure 17(A) is made of multiple materials. It may be formed in this way. For example, the lithium-ion battery 913 shown in Figure 17(B) has a housing 93 0a and casing 930b are bonded together, and the area enclosed by casing 930a and casing 930b A winding body 950 is provided in the region.

[0204] For the enclosure 930a, insulating materials such as organic resins can be used. In particular, the antenna By using a material such as organic resin on the surface where the na is formed, lithium-ion battery 913 This can suppress the shielding of the electric field by the housing 930a. An antenna may be provided inside the body 930a. For the housing 930b, for example, a metal material may be used. It can be used.

[0205] Furthermore, the structure of the wound body 950 is shown in Figure 17(C). The wound body 950 is the negative electrode 93 It has a positive electrode 932 and an electrolyte layer 933. The wound body 950 has an electrolyte layer 933. The negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the stacked sheet is rolled up. It is a rotating body. Furthermore, the stacking of the negative electrode 931, the positive electrode 932, and the electrolyte layer 933 is further Multiple layers can be stacked.

[0206] Furthermore, lithium i having a wound body 950a as shown in Figures 18(A) to 18(C) It may also be called an on-cell 913. The wound body 950a shown in Figure 18(A) has a negative electrode 931 and a positive It has an electrode 932 and an electrolyte layer 933. The negative electrode 931 has a negative electrode active material layer 931a. The positive electrode 932 has a positive electrode active material layer 932a.

[0207] The electrolyte layer 933 has a wider width than the negative electrode active material layer 931a and the positive electrode active material layer 932a. Furthermore, it is wound so as to overlap the negative electrode active material layer 931a and the positive electrode active material layer 932a. Furthermore, the fact that the negative electrode active material layer 931a is wider than the positive electrode active material layer 932a is preferable in terms of safety. Furthermore, a coiled body 950a of this shape is preferable due to its good safety and productivity.

[0208] As shown in Figure 18(B), the negative electrode 931 is electrically connected to terminal 951. Terminal 95 Terminal 1 is electrically connected to terminal 911a. Also, the positive terminal 932 is electrically connected to terminal 952. Terminal 952 is electrically connected to terminal 911b.

[0209] As shown in Figure 18(C), the coiled body 950a is covered by the housing 930, and lithium io This becomes the battery 913. It is preferable to provide a safety valve, overcurrent protection element, etc., in the housing 930. The safety valve is a valve that opens when the inside of the housing 930 reaches a predetermined internal pressure in order to prevent the battery from rupturing. ru.

[0210] As shown in Figure 18(B), the lithium-ion battery 913 has a plurality of wound bodies 950a. It is acceptable. By using multiple wound bodies 950a, a lithium battery with a larger charge / discharge capacity can be obtained. It can be an on-battery 913. Lithium-ion battery shown in Figures 18(A) and (B). Other elements of 913 are shown in Figures 17(A) to 17(C) of the lithium-ion battery 913. You can refer to the information provided.

[0211] By using the positive electrode active material of the present invention in a lithium-ion battery 913 having a wound body, This allows for the creation of a secondary battery with high capacity, high discharge capacity, and excellent cycle characteristics. .

[0212] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0213] (Embodiment 4) In this embodiment, an example of application to an electric vehicle (EV) is shown using Figure 19.

[0214] As shown in Figure 19(A), electric vehicles use lithium-ion batteries as the main drive battery. The first batteries 1301a and 1301b and the inverter 1 that starts the motor 1304 A second battery 1311 is installed to supply power to 312. By using the positive electrode active material of the present invention in 01a and 1301b, high capacity and discharge capacity can be achieved. This allows for the creation of a secondary battery with high performance and excellent cycle characteristics.

[0215] The second battery, 1311, is the cranking battery (also known as the starter battery). It is also called (). The second battery 1311 only needs to be able to output high power, and large capacity is not so necessary. It is not required, and the capacity of the second battery 1311 is the same as that of the first batteries 1301a and 1301b. It's relatively small.

[0216] The internal structure of the first battery 1301a may be wound or stacked. That's good. Alternatively, the first battery 1301a may be the secondary battery described in the previous embodiment. By using the secondary battery of the previous embodiment for the first battery 1301a, a high capacity can be achieved. This allows for improved safety, miniaturization, and weight reduction.

[0217] In this embodiment, the first batteries 1301a and 1301b are connected in parallel. The example shown is that three or more can be connected in parallel. Also, the first battery 1301a If sufficient power can be stored, the first battery 1301b is not necessary. By configuring a battery pack that has lithium-ion batteries, it is possible to extract a large amount of power. This is possible. Multiple lithium-ion batteries may be connected in parallel or in series. They may be connected in parallel and then further connected in series. Multiple lithium A ion battery is also called a battery pack.

[0218] Furthermore, in automotive lithium-ion batteries, power from multiple lithium-ion batteries To interrupt the high voltage, use a service plug or circuit breaker that can interrupt the high voltage without the use of tools. It has a power supply and is provided in the first battery 1301a.

[0219] Furthermore, the power from the first batteries 1301a and 1301b is mainly used to rotate the motor 1304. It is used to power 42V automotive components (electric power) via the DC-DC circuit 1306. It supplies power to the steering wheel (1307, heater 1308, defogger 1309, etc.). Even when the rear motor 1317 is present, the first battery 1301a is connected to the rear motor 131 It is used to rotate the number 7.

[0220] Furthermore, the second battery 1311 is connected to 14V automotive components via the DC-DC circuit 1310. (Supplies power to audio 1313, power windows 1314, lights 1315, etc.) To give.

[0221] Furthermore, the first battery 1301a will be explained using Figure 19(B).

[0222] Figure 19(B) shows nine rectangular lithium-ion batteries 1300 in one battery pack 1415 This shows an example of connecting nine rectangular lithium-ion batteries 1300 in series. One electrode is fixed with a fixing part 1413 made of an insulator, and the other electrode is made from an insulator. It is fixed by the fixing part 1414. In this embodiment, it is fixed by the fixing parts 1413 and 1414. The example shown involves housing the battery in a battery compartment (also called the casing). Since vehicles are designed to withstand vibrations or shaking from external sources (such as the road surface), they are fixed. Multiple lithium-ion batteries are secured in parts 1413, 1414 and the battery housing box. This is preferable. Also, one electrode is electrically connected to the control circuit unit 1320 by the wiring 1421. The other electrode is electrically connected to the control circuit unit 1320 by wiring 1422. It continues.

[0223] Furthermore, the control circuit unit 1320 includes a memory circuit that includes a transistor using an oxide semiconductor. It may be used. A charge control circuit having a memory circuit including an oxide semiconductor transistor. A road or battery control system is called a BTOS (Battery operating system). In places where it is called tem, or Battery oxide semiconductor There is a match.

[0224] It is preferable to use a metal oxide that functions as an oxide semiconductor. For example, as In-M-Zn oxide (element M is aluminum, gallium, yttrium, copper, etc.) Nadium, beryllium, boron, titanium, iron, nickel, germanium, zirconium, Molybdenum, lanthanum, cerium, neodymium, hafnium, tantalum, tungsten, and It is preferable to use a metal oxide such as one or more selected from magnesium. In particular, In-M-Zn oxides that can be applied as oxides include CAAC-OS(C-Axis Al igned Crystal Oxide Semiconductor), CAC-O S(Cloud-Aligned Composite Oxide Semiconductor It is preferable that it be uctor. Also, as oxides, In-Ga oxide, In-Z n oxide may also be used. CAAC-OS has multiple crystalline regions, and these multiple crystalline regions The region is an oxide semiconductor in which the c-axis is oriented in a specific direction. The specific direction is CA. The thickness direction of the AC-OS film, the normal direction of the surface on which the CAAC-OS film is formed, or CAAC-OS This is the normal direction to the surface of the film. Furthermore, a crystalline region is a region where the atomic arrangement exhibits periodicity. Furthermore, if we consider the atomic arrangement as a lattice arrangement, then a crystalline region is also a region where the lattice arrangement is aligned. Furthermore, CAAC-OS has regions where multiple crystalline regions are connected in the ab-plane direction. Furthermore, the region in question may have distortion. Distortion refers to the area where multiple crystal regions are connected. Within the region, between a region with aligned lattice arrangements and another region with aligned lattice arrangements, This refers to the area where the orientation changes. In other words, CAAC-OS is c-axis oriented and ab-plane oriented. It is an oxide semiconductor that does not exhibit clear orientation.

[0225] Furthermore, since it can be used in low-temperature environments, the control circuit section 1320 uses an oxide semiconductor. It is preferable to use a transistor. To simplify the process, control circuit section 1 320 may be formed using a unipolar transistor. An oxide semiconductor is used for the semiconductor layer. The transistor has an operating ambient temperature range that is wider than that of a single-crystal Si transistor, above -40°C. The temperature is below 0°C, and even if the lithium-ion battery is heated, the characteristics do not change as they do in a single-crystal Si transistor. It is smaller in comparison. The off-current of a transistor using an oxide semiconductor is small even at 150°C. Although it is below the lower limit of measurement regardless of the temperature, the off-current characteristics of a single-crystal Si transistor are temperature-dependent. The effect is significant. For example, at 150°C, the off-current of a single-crystal Si transistor increases, and the current... The on / off ratio does not become sufficiently large. The control circuit unit 1320 improves safety. can.

[0226] The control circuit section 1320, which uses a memory circuit including an oxide semiconductor transistor, Automatic control of lithium-ion batteries to address 10 causes of instability, such as micro-short circuits. It can also function as a device. Its function to eliminate 10 causes of instability includes: Overcharge prevention, overcurrent prevention, overheat control during charging, cell balancing in battery packs, and over-discharge prevention. Stop function, remaining battery indicator, automatic control of charging voltage and current according to temperature, and charging current control according to degradation level. Examples include detecting abnormal behavior in micro-short circuits and predicting anomalies related to micro-short circuits. The control circuit unit 1320 has at least one of these functions. It is possible to miniaturize the automatic control device for batteries.

[0227] Furthermore, a micro-short refers to a tiny short circuit inside a lithium-ion battery. One of the causes of microshorts is that the positive electrode active material deteriorates due to multiple charge-discharge cycles. Due to the non-uniform distribution, localized current concentration occurs in parts of the positive and negative electrodes, or side reactions occur. It is said that the generation of by-reactants causes microscopic short circuits.

[0228] In addition to detecting micro-shorts, the control circuit unit 1320 also detects lithium-ion batteries. It can also be said that it detects the terminal voltage of the battery and manages the charging and discharging state of the lithium-ion battery. To prevent overcharging, both the output transistor and the cutoff switch of the charging circuit are switched on almost simultaneously. It can be turned off.

[0229] Furthermore, an example of a block diagram of the battery pack 1415 shown in Figure 19(B) is shown in Figure 19(C). vinegar.

[0230] The control circuit unit 1320 includes at least a switch to prevent overcharging and a switch to prevent over-discharging. A switch unit 1324 including a switch, and a control circuit 1322 that controls the switch unit 1324. The control circuit unit 1320 has a voltage measuring unit for the first battery 1301a. The lithium-ion battery has set upper and lower voltage limits, and an upper limit on the current from an external source, and It also limits the upper limit of the output current to the outside. Voltages below this range are within the recommended voltage range for use, and voltages outside this range will cause problems. The switch unit 1324 is activated and functions as a protection circuit. In addition, the control circuit unit 1320 switches The switch section 1324 controls the circuit to prevent over-discharge and over-charge, and can therefore be called a protection circuit. If the control circuit 1322 detects a voltage that is likely to cause overcharging, the switch unit 1324 will The current is cut off by turning the switch to the OFF state. Furthermore, a PTC element is installed in the charge / discharge path. A function may be provided to interrupt the current in response to the rise in temperature. Also, the control circuit unit 1320 It has an external terminal 1325 (+IN) and an external terminal 1326 (-IN).

[0231] The switch section 1324 uses an n-channel transistor and a p-channel transistor. It can be constructed by combining these. The switch section 1324 uses single-crystal silicon. Switches are not limited to those having Si transistors; for example, they can also have Ge (germanium), Si Ge (silicon germanium), GaAs (gallium arsenide), GaAlAs (gallium arsenide) Aluminum arsenide, InP (indium phosphide), SiC (silicon carbide), Zn Se (zinc selenide), GaN (gallium nitride), GaO x (Gallium oxide; x is greater than 0) The switch section 1324 may be formed using a power transistor having a large real number (or similar). Furthermore, memory elements using OS transistors can be integrated into circuits using Si transistors, etc. Because it can be freely arranged by layering, integration can be easily achieved. Switch section By stacking the control circuit section 1320, which uses OS transistors, on top of 1324 and integrating them, It can be integrated into a single chip, enabling miniaturization.

[0232] The first batteries, 1301a and 1301b, are primarily used to power 42V (high-voltage) in-vehicle equipment. The second battery 1311 supplies power to 14V (low-voltage) in-vehicle equipment. The second battery, 1311, is often a lead-acid battery because it is more cost-effective. By using a lithium-ion battery for battery 1311, the merit of making it maintenance-free. Although there is a risk of malfunction, prolonged use, such as more than 3 years, can lead to abnormalities that were not detectable at the time of manufacture. There is a risk of failure. In particular, if the second battery 1311 that starts the inverter becomes inoperable. This means that even if the first batteries 1301a and 1301b have remaining capacity, the motor will start. To prevent this from becoming impossible, if the second battery 1311 is a lead-acid battery, then the first Power is supplied from the first battery to the second battery, and it is kept charged to maintain a constantly fully charged state. It is being done.

[0233] In this embodiment, both the first battery 1301a and the second battery 1311 are supplied with lithium An example using a um-ion battery is shown, but the second battery 1311 is a lead-acid battery, a solid-state battery. Alternatively, an electric double-layer capacitor may be used. By using a positive electrode active material, high capacity, high discharge capacity, and excellent cycle characteristics are achieved. It can be used as a secondary battery.

[0234] Furthermore, the regenerative energy from the rotation of the tire 1316 is transmitted to the motor 1 via the gear 1305. It is sent to 304 and from the motor controller 1303 and battery controller 1302 The second battery 1311 is charged via the control circuit unit 1321. The first battery 1301a is charged from the Troller 1302 via the control circuit unit 1320. Alternatively, the first battery is transmitted from the battery controller 1302 via the control circuit unit 1320. It is charged to battery 1301b. In order to efficiently charge with regenerative energy, the first battery It is desirable that the Ri1301a and Ri1301b models be capable of rapid charging.

[0235] The battery controller 1302 controls the charging voltage of the first batteries 1301a and 1301b. The charging current and other parameters can be set. The battery controller 1302 uses By setting charging conditions according to the charging characteristics of the lithium-ion battery, rapid charging can be achieved. .

[0236] Also, although not shown in the diagram, when connecting to an external charger, the charger's outlet or charging port The electrical connection cable is electrically connected to the battery controller 1302. Power supplied from the charger is transmitted to the first battery 1 via the battery controller 1302. Charges 301a and 1301b. Also, some chargers have a control circuit. Although the functions of the battery controller 1302 may not be used, the control is used to prevent overcharging. It is preferable to charge the first batteries 1301a and 1301b via the circuit section 1320. Also, the connection cable or the charger's connection cable may have a control circuit. The control circuit unit 1320 is an ECU (Electronic Control Unit) It is sometimes called an ECU. An ECU is a CAN (Controller) installed in electric vehicles. It connects to an Area Network. CAN is used as an in-vehicle LAN. It is one of the real communication standards. Also, an ECU includes a microcomputer. CU uses either a CPU or a GPU.

[0237] External chargers installed at charging stations, etc., use 100V outlets and 200V outlets. There are various types, such as contactless power supply systems, 3-phase 200V and 50kW. Additionally, external power supply systems such as contactless power supply are available. It can also be charged by receiving power from a charging facility.

[0238] Next, a lithium-ion battery according to one aspect of the present invention is implemented in a vehicle, typically a transport vehicle. Let's explain an example.

[0239] Furthermore, when lithium-ion batteries are installed in vehicles, hybrid vehicles (HV) and electric vehicles are created. Next-generation clean energy vehicles such as electric vehicles (EVs) or plug-in hybrid vehicles (PHVs) It can be used to create cars. Also, agricultural machinery, motorized bicycles including electric-assist bicycles, and motorcycles. Cars, electric wheelchairs, electric carts, small or large vessels, submarines, fixed-wing aircraft and rotary-wing aircraft, etc. Lithium is used in transport vehicles for aircraft, rockets, satellites, space probes, planetary probes, and spacecraft. It can also be equipped with a micro-ion battery.

[0240] Figures 20(A) to 20(D) illustrate a transport vehicle using one embodiment of the present invention. The automobile 2001 shown in Figure 20(A) uses an electric motor as the power source for driving. It is an electric vehicle. Alternatively, an electric motor and an engine can be appropriately selected as the power source for driving. It is a hybrid vehicle that can be used in this way. It is equipped with a lithium-ion battery. In this case, the example of the lithium-ion battery shown in the above embodiment can be installed in one or more locations. By using the positive electrode active material of the present invention in lithium-ion batteries installed in vehicles, high capacity This allows for the creation of a secondary battery with high capacity, high discharge capacity, and excellent cycle characteristics.

[0241] The automobile 2001 shown in Figure 20(A) has a battery pack 2200, and the battery pack is multi It has a battery module with several lithium-ion batteries connected. Furthermore, battery pack 220 It is preferable that 0 has a charge control device electrically connected to the battery module.

[0242] Furthermore, the automobile 2001 has a lithium-ion battery that plugs into the automobile 2001. It can be charged by receiving power from an external charging facility using a contactless power supply method, etc. It can be used. When charging, the charging method and connector specifications are based on CHAdeMO (registered trademark). This can be done as appropriate using a prescribed method such as a combo. Lithium-ion batteries are installed in commercial facilities. It can be a charging station or a household power source. For example, plug-in technology This allows the battery storage device installed in the automobile 2001 to be charged by an external power supply. This is possible. Charging is done by converting AC power to DC power via a conversion device such as an AC / DC converter. It can be done by conversion.

[0243] Although not shown in the diagram, a power receiving device is mounted on the vehicle, and power is supplied wirelessly from a ground-based power transmission device. It can also be charged by supplying power. In this contactless power supply method, the power transmission device is located on the road or exterior wall. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. The power supply method may be used to allow two vehicles to send and receive power from each other. Furthermore, the vehicles Solar panels may be installed on the exterior to charge the lithium-ion battery while the vehicle is stopped or in motion. For such contactless power supply, electromagnetic induction or magnetic resonance methods can be used. can.

[0244] Figure 20(B) shows a large transport vehicle equipped with an electrically controlled motor as an example of a transport vehicle. This shows vehicle 2002. The battery module of vehicle 2002 has a nominal voltage of, for example, 3.0 Four lithium-ion batteries with a voltage between 5.0V and 6.0V are used as cell units, and 48 cells are connected in series. The maximum voltage will be 170V. The number of lithium-ion batteries in the battery pack 2201, etc. Aside from the differences, it has the same functions as Figure 19(B), so the explanation will be omitted. Battery Pack 2 By using the positive electrode active material of the present invention in a lithium-ion battery, high capacity and discharge This allows for the creation of a secondary battery with high electrical capacity and excellent cycle characteristics.

[0245] Figure 20(C) shows, as an example, a large transport vehicle 200 equipped with an electrically controlled motor. It shows 3. The battery module of the transport vehicle 2003 has a nominal voltage of 3.0V or more, for example 5. The maximum voltage is 600V, achieved by connecting more than 100 lithium-ion batteries with a voltage of 0V or less in series. Also, the number of lithium-ion batteries that make up the battery module of the battery pack 2202 may differ. Except for the above, it has the same functions as Figure 19(B), so the explanation will be omitted. Battery module By using the positive electrode active material of the present invention in a lithium-ion battery, a high capacity and discharge rate can be achieved. This allows for the creation of a secondary battery with high electrical capacity and excellent cycle characteristics.

[0246] Figure 20(D) shows, as an example, aircraft 2004 having a fuel-burning engine. Yes. The aircraft 2004 shown in Figure 20(D) has landing gear for takeoff and landing, so it can be transported by It can be said that both are part of a battery module, which is constructed by connecting multiple lithium-ion batteries. It has a battery pack 2203 which includes a battery module and a charging control device.

[0247] The battery module for the aircraft 2004 uses, for example, eight 4V lithium-ion batteries connected in series. The maximum voltage is 32V. The lithium battery module of the battery pack 2203 is composed of Aside from differences in the number of ion batteries, it has the same functions as Figure 19(B), so the explanation is as follows: Omitted.

[0248] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0249] (Embodiment 5) In this embodiment, a lithium-ion battery according to one aspect of the present invention is installed in a vehicle such as a motorcycle or bicycle. This shows an example of a system with a pond.

[0250] Figure 21(A) shows an example of an electric bicycle using a lithium-ion battery according to one embodiment of the present invention. The electric bicycle 8700 shown in Figure 21(A) is fitted with a lithium-ion battery according to one embodiment of the present invention. It can be applied. A lithium-ion battery according to one aspect of the present invention may have a protection circuit. .

[0251] The electric bicycle 8700 is equipped with a power storage device 8702. The power storage device 8702 provides power to the driver. It can supply electricity to the motor that is being operated. Also, the energy storage device 8702 is portable. This can be done, and Figure 21(B) shows the state after it has been removed from the bicycle. Also, the energy storage device 870 2 has multiple lithium-ion batteries 8701 according to one aspect of the present invention built in, and the battery The remaining charge and other information can be displayed on the display unit 8703. Lithium-ion battery 8701 By using the positive electrode active material of the present invention, a high capacity and high discharge capacity are achieved, and cycle This allows for the creation of a secondary battery with excellent performance characteristics.

[0252] Furthermore, the energy storage device 8702 has a control function that can control the charging of the lithium-ion battery or detect abnormalities. It has a circuit 8704. The control circuit 8704 controls the positive and negative electrodes of the lithium-ion battery 8701. It is electrically connected to it. This will greatly contribute to eliminating accidents such as fires caused by lithium-ion batteries. It is possible.

[0253] Figure 21(C) shows an example of a motorcycle using a lithium-ion battery according to one embodiment of the present invention. The scooter 8600 shown in Figure 21(C) includes a power storage device 8602, side mirrors 8601, and It is equipped with a turn signal light 8603. The energy storage device 8602 supplies electricity to the turn signal light 8603. It is possible to achieve high capacity and In addition, it is possible to create a secondary battery with high discharge capacity and excellent cycle characteristics.

[0254] The scooter 8600 shown in Figure 21(C) has a power storage device 8602 in the under-seat storage compartment 8604. It can be stored. The power storage device 8602 can be stored even if the under-seat storage 8604 is small. It can be stored in the under-seat storage compartment 8604.

[0255] The contents of this embodiment can be appropriately combined with the contents of other embodiments.

[0256] (Embodiment 6) This embodiment provides an example of mounting a lithium-ion battery, which is one aspect of the present invention, into an electronic device. This will explain. Examples of electronic devices that implement lithium-ion batteries include televisions. Television equipment (also called television or television receiver), monitors for computers, etc. Digital cameras, digital video cameras, digital photo frames, mobile phones (mobile phones) (Also called mobile phone devices), portable game consoles, personal information terminals, sound playback devices, pachinko machines Examples include large game consoles. As for portable information terminals, there are notebook-type personal computers. These include computers, tablet devices, e-readers, and mobile phones.

[0257] Figure 22(A) shows an example of a mobile phone. The mobile phone 2100 has a housing 210 In addition to the display unit 2102 incorporated into 1, there are also operation buttons 2103, an external connection port 2104, It is equipped with speaker 2105, microphone 2106, etc. Note that the mobile phone 2100 is... The lithium-ion battery 2107 is provided. The positive electrode active material of the present invention is used in the lithium-ion battery. By using it, a secondary battery with high capacity, high discharge capacity, and excellent cycle characteristics can be obtained. It is possible.

[0258] The mobile phone 2100 is a mobile phone that can make calls, send emails, read and create documents, play music, and interact with other devices. - It can run various applications such as network communication and computer games. ru.

[0259] The operation button 2103 is used for setting the time, as well as turning the power on and off, turning wireless communication on, and more. Various functions such as operation, activation and deactivation of silent mode, and activation and deactivation of power saving mode. It can be made to hold. For example, the operating system built into the mobile phone 2100 The stem also allows you to freely configure the function of the operation button 2103.

[0260] Furthermore, the mobile phone 2100 is capable of performing standardized short-range wireless communication. Yes, for example, by communicating with a wireless headset, hands-free operation is possible. You can also make phone calls.

[0261] Furthermore, the mobile phone 2100 is equipped with an external connection port 2104, and can connect to other information terminals. Data can be exchanged directly via this. Also, via external connection port 2104... It can also be charged wirelessly. Note that the charging operation is performed wirelessly without going through the external connection port 2104. It may also be done by electricity.

[0262] The mobile phone 2100 preferably has a sensor. For example, a fingerprint sensor. Human body sensors such as pulse sensors and body temperature sensors, touch sensors, pressure sensors, and acceleration sensors. It is preferable that the following are installed:

[0263] Figure 22(B) shows an unmanned aerial vehicle 2300 having multiple rotors 2302. The aircraft 2300 is sometimes called a drone. The unmanned aerial vehicle 2300 is, in one aspect of the present invention It has a lithium-ion battery 2301, a camera 2303, and an antenna (not shown). The unmanned aerial vehicle 2300 can be remotely controlled via an antenna. Lithium-ion By using the positive electrode active material of the present invention in a battery, a high capacity and high discharge capacity can be achieved. This can be used to create a secondary battery with excellent cycling properties.

[0264] Figure 22(C) shows an example of a robot. The robot 6400 shown in Figure 22(C) This includes a lithium-ion battery 6409, an illuminance sensor 6401, a microphone 6402, and the top Camera 6403, speaker 6404, display unit 6405, lower camera 6406 and obstacle sensor It is equipped with a sensor 6407, a moving mechanism 6408, a computing device, and the like.

[0265] Microphone 6402 has the function of detecting the user's voice and ambient sounds, etc. Furthermore, speaker 6404 has the function of emitting sound. Robot 6400 is microf Using the phone 6402 and speaker 6404, communication with the user is possible. It is possible.

[0266] The display unit 6405 has the function of displaying various information. The robot 6400 is used It is possible to display the information desired by the user on the display unit 6405. The display unit 6405 is a touch It may also be equipped with a control panel. Furthermore, the display unit 6405 is a removable information terminal. It is also fine to install it in a fixed position on the robot 6400, allowing for charging and data transfer. Make it possible.

[0267] The upper camera 6403 and lower camera 6406 are used to image the area around the robot 6400. It has the ability to move the robot 6407 using the moving mechanism 6408. Robot 64 can detect the presence or absence of obstacles in the direction of travel as it moves forward. 00 uses the upper camera 6403, the lower camera 6406 and the obstacle sensor 6407, It is possible to perceive the surrounding environment and move around safely.

[0268] The robot 6400 has a lithium-ion battery 640 according to one aspect of the present invention in its internal region. 9 comprises a semiconductor device or electronic component. The positive electrode active material of the present invention is used in a lithium-ion battery. By using it, a secondary battery with high capacity, high discharge capacity, and excellent cycle characteristics can be obtained. It is possible.

[0269] Figure 22(D) shows an example of a cleaning robot. The cleaning robot 6300 has a housing 6 301 A display unit 6302 positioned on the top surface, multiple cameras 6303 positioned on the side, It includes components such as the C6304, operation buttons 6305, lithium-ion battery 6306, and various sensors. Although not shown in the illustration, the cleaning robot 6300 is equipped with wheels, a suction port, etc. The cleaning robot 6300 moves autonomously, detects the dirt 6310, and uses a suction device located on its underside. It can suck up debris from the intake port.

[0270] For example, the cleaning robot 6300 analyzes images captured by the camera 6303 to identify walls, furniture, etc. Alternatively, it can determine the presence or absence of obstacles such as steps. Furthermore, image analysis can detect wiring, etc. If an object that may become entangled in the brush 6304 is detected, the rotation of the brush 6304 will be stopped. This is possible. The cleaning robot 6300 has a lithium-ion battery according to one aspect of the present invention in its internal region. The present invention comprises an on-cell 6306 and a semiconductor device or electronic component. By using this positive electrode active material, high capacity, high discharge capacity, and excellent cycle characteristics are achieved. It can be used as a secondary battery.

[0271] This embodiment can be implemented in appropriate combination with other embodiments.

[0272] (Embodiment 7) In this embodiment, a lithium-ion battery, which is one aspect of the present invention, is implemented in space equipment. Let me explain with an example.

[0273] Figure 23(A) shows the satellite 6800 as an example of space equipment. Star 6800 consists of the aircraft 6801, solar panel 6802, antenna 6803, and lithium It has a 6805 um-ion battery. The solar panel is called a solar cell module. There are cases where this occurs.

[0274] When sunlight shines on solar panel 6802, satellite 6800 operates. The necessary electricity is generated for this purpose. However, for example, when sunlight shines on a solar panel... In situations where there is no sunlight, or where the amount of sunlight hitting the solar panel is low, The amount of power generated will decrease. Therefore, the power required for satellite 6800 to operate will decrease. It may not be possible. Even under conditions where the generated power is low, the 6800 satellite... To operate it, it is recommended to equip satellite 6800 with a lithium-ion battery 6805. By using the positive electrode active material of the present invention in a lithium-ion battery, high capacity and high discharge capacity can be achieved. Furthermore, it can be made into a secondary battery with excellent cycle characteristics.

[0275] Satellite 6800 can generate a signal. This signal is transmitted to antenna 6803. The signal is transmitted via a receiver, for example, located on the ground, or received by another satellite. This is possible. By receiving the signal transmitted by satellite 6800, for example, The position of the receiver that received the signal can be measured. Therefore, artificial satellite 6800 is For example, a satellite positioning system can be configured.

[0276] Alternatively, the satellite 6800 can be configured to have sensors. For example, By having a configuration that includes a light-gathering sensor, the artificial satellite 6800 is located on the ground. It can have the function of detecting sunlight that has struck an object and been reflected. Or, thermal infrared By having a sensor configuration, the 6800 satellite can detect thermal infrared radiation emitted from the Earth's surface. It can have the function of detecting lines. Therefore, the artificial satellite 6800 can, for example, Earth It can function as an observation satellite.

[0277] Figure 23(B) shows an example of space equipment: a solar sail (also called a solar sail). This shows the probe 6900. The probe 6900 consists of the main body 6901 and the solar sail It comprises 6902 and a lithium-ion battery 6905. The present invention relates to the lithium-ion battery. By using this positive electrode active material, high capacity, high discharge capacity, and excellent cycle characteristics are achieved. It can be used as a secondary battery. Photons emitted from the sun are used by the solar sail 6902 When it hits the surface, momentum is transferred to the solar sail 6902. Therefore, solar The surface of sail 6902 preferably has a highly reflective thin film, and furthermore, it faces the direction of the sun. This is preferable.

[0278] Furthermore, Solar Sail 6902 remains in a compact, folded state until it exits the atmosphere. Outside the Earth's atmosphere (in outer space), it unfolds into a large sheet-like structure, as shown in Figure 23(B). It may be designed that way.

[0279] Figure 23(C) shows spacecraft 6910 as an example of space equipment. 910 consists of the airframe 6911, the solar panel 6912, and the lithium-ion battery 6913. , has. By using the positive electrode active material of the present invention in a lithium-ion battery, high capacity and This allows for the creation of a secondary battery with high discharge capacity and excellent cycle characteristics. (Unit 69) 11 can, for example, have a pressurized chamber and an unpressurized chamber. The pressurized chamber is designed to accommodate the crew. This is also acceptable. The electricity generated when sunlight is shone on the solar panel 6912 is lithium It can charge the 6913 um-ion battery.

[0280] Figure 23(D) shows Rover 6920 as an example of space equipment. The 920 comprises an airframe 6921 and a lithium-ion battery 6923. By using the positive electrode active material of the present invention in a battery, a high capacity and high discharge capacity can be achieved. It can be used to create a secondary battery with excellent rechargeable properties. The rover 6920 has 6 solar panels. It may have 922.

[0281] Rover 6920 may be designed to accommodate a crew. Solar panel 6912 will be used for solar power. The electricity generated by the irradiation of light may be used to charge the lithium-ion battery 6923, or Electricity generated by other power sources, such as fuel cells and radioisotope thermoelectric converters, You may also charge the 6923 lithium-ion battery.

[0282] The contents of this embodiment can be appropriately combined with the contents of other embodiments. [Examples]

[0283] In this embodiment, a positive electrode active material according to one aspect of the present invention is prepared, its characteristics are analyzed, and its electrochemical properties are examined. The characteristics were evaluated.

[0284] <Fabrication of positive electrode active material> A positive electrode active material according to one embodiment of the present invention was synthesized according to the flowchart shown in Figure 2. Figure 2 As shown, commercially available LCO powder is mixed with magnesium, nickel, and aluminum. I performed a ping.

[0285] For synthesis, MgF2 (99.9% purity), LiF (99% purity), Ni(OH)2( (purity 99.9%), Al(OH)3 (purity 99.99%), LiCoO2 (purity 99%, C-10N (manufactured by Nippon Chemical Industrial Co., Ltd.) was used. In addition, untreated C-10N was used as the original L CO was used as a comparative example.

[0286] A muffle furnace was used for all heating steps, and the samples were placed in alumina crucibles.

[0287] First, the original LCO (D50 12.5μm) was subjected to an oxygen atmosphere without the addition of any additive elements. Preheated in air at 850°C for 2 hours. In the first addition step, preheated LCO, M Weigh gF2 and LiF in a molar ratio of 1:0.01:0.003 and mix them together. This mixture was heated at 900°C for 20 hours under an oxygen atmosphere. In the second addition step, The LCO, Ni(OH)2, and Al(OH)3 obtained in the 1st addition step were each added in a 1:0 ratio. The mixture was mixed in a molar ratio of 0.005:0.005. This mixture was incubated at 850°C under an oxygen atmosphere for 10 minutes. It was heated for a certain amount of time.

[0288] For further comparison, we have Mg(OH)2, MgF2-LiF, and LiF-Ni(OH)2. LiF-Al(OH)3, LiF-Ni(OH)2-Al(OH)3, LiF, Ni(O H)2-Al(OH)3, MgF2-LiF-Ni(OH)2, MgF2-LiF-Al Synthesize using the same procedure by adding only (OH)3, and then convert these to M-LCO, MF-LCO, and F N-LCO, FA-LCO, FNA-LCO, F-LCO, NA-LCO, MFN-LC The samples used were O and MFA-LCO. For LCO heated only, the same first and second tests were performed without any added elements. Only heating was performed. The original LCO did not undergo the heating process.

[0289] To synthesize M-LCO, preheated LCO is mixed with Mg(OH)2 in a 1:0.01 ratio. The mixture was combined in the molar ratio and heated in the same manner as in the first addition step described above. Then, preheated LCO, MgF2, and LiF are added in a ratio of 1:0.0, 1:0.0, respectively. After mixing at a molar ratio of 0.3, the mixture was heated in the same manner as in the first addition step. These products were then finally The mixture was then subjected to the same heating process as in the second addition step without adding any additional elements, and the final product was obtained.

[0290] For FN-LCO, FA-LCO, FNA-LCO, and F-LCO, preheating is required. Mix the prepared LCO and LiF in a molar ratio of 1:0.023 and heat in the same manner as in the first addition step. The process was carried out. The resulting LCO was mixed with Ni(OH)2 or Al(OH)3 in a 1:0.005 ratio. In a mole ratio, or Ni(OH)2 and Al(OH)3 in a 1:0.005:0.005 mole ratio. After mixing in the specified ratio, the mixture was subjected to a heating process similar to the second addition step.

[0291] In the synthesis of NA-LCO, the additive elements are added to the preheated LCO before the first heating. It was not done. The LCO subjected to the first heating was Ni(OH)2 and Al(OH)3 in a 1:0 ratio. The mixture was mixed in a molar ratio of 0.005:0.005 and then subjected to a second heating process. MFN-LC In the synthesis of O and MFA-LCO, preheated LCO, MgF2, and LiF are used in a 1: After mixing in a molar ratio of 0.01:0.003, the mixture was subjected to the first heating step. The resulting LCO After mixing with Ni(OH)2 or Al(OH)3 in a molar ratio of 1:0.005, the second The LCO was subjected to a heating process. Similarly, LCO was subjected to the first and second heating processes without the addition of elements. It was manufactured through a heat process.

[0292] <Morphological and structural analysis> ≪XRD≫ Figures 24(A) to 24(C) show the positive electrode active material of one embodiment of the present invention and the original LCO powder XR The D pattern and the reference pattern are shown. The positive electrode active material and the original LCO powder X according to one embodiment of the present invention. The RD pattern showed the O3 phase and space group R-3m; no other phases were observed.

[0293] Table 2 also shows the Rietveld refinement results of the powder XRD patterns of various samples. For string refinement, DIFFRAC.TOPAS ver.6 was used, and the Li of the space group R-3m was used. The analysis was performed assuming it was a single phase of CoO2. The c-axis length of the positive electrode active material in one embodiment of the present invention is the original L The slight increase compared to CO is due to nickel and aluminum doping. There is a possibility. In addition, since the change in the a-axis length is very slight, the cobalt site This suggests that the amount of magnesium substituted is small.

[0294] [Table 2]

[0295] ≪SEM≫ Figures 25(A) and 25(B) show scanning electron microscope (SEM) images of the original LCO. Figures 25(C) and 25(D) show SEM images of a positive electrode active material according to one embodiment of the present invention. The bars in Figures 25(A) and 25(C) are 10 μm, and in Figures 25(B) and 25(D) The bar is 2 μm. The SEM image was taken with a Hitachi SU4800 or SU80 at an acceleration voltage of 5 kV. The images were acquired using a field emission SEM (FE-SEM).

[0296] From these findings, the surface of the positive electrode active material in one embodiment of the present invention is smoother than the surface of the original LCO. It was found that during the heating process, the surface of the LCO particles and the molten fluoride salt partially melted. This is thought to be the reason.

[0297] ≪SEM-EDX≫ Figures 26(A) to 27(F) show the steps in the synthesis of a positive electrode active material according to one embodiment of the present invention. The image shows an SEM-EDX mapping. The SEM image was taken using a Hitachi SU4800 or SU8030. The data was acquired using a field emission SEM (FE-SEM) with an acceleration voltage of 5kV. (SEM-EDX) This is an EMAX Evolution EX-370 (manufactured by HORIBA), with an acceleration voltage of 15kV. This was done. Figures 26(A) and 26(B) are SEM images of the original LCO, and Figure 26(C) is approximately Figure 26(D) is an SEM image of a preheated LCO. Figures 26(E) and 26( F) SEM image of a preheated mixture of LCO, LiF, and MgF2, Figure 26(G). Figure 26(H) shows SEM-EDX mapping images of each element in the same region as Figure 26(F). Figure 26(I) shows an SEM image of LCO doped with magnesium and fluorine, and Figure 26(J) Figure 27(A) shows SEM-EDX mapping images of each element in the same region as Figure 26(I). Figure 27(B) shows LCO, Ni(OH)2 and A with added magnesium and fluorine. SEM image of l(OH)3 mixture, Figure 27(C) shows the S of each element in the same region as Figure 27(B). This is an EM-EDX mapping image. Figures 27(D) and 27(E) show one embodiment of the present invention. SEM images of the positive electrode active material; Figure 27(F) shows SEM-ED images of each element in the same region as Figure 27(E). These are X-mapped images. Figures 26(A), 26(C), 26(E), 26(H), Figure The bars in 27(A) and 27(D) are 50 μm, as in Figures 26(B), 26(D), and 26 (F), Figure 26(G), Figure 26(I), Figure 26(J), Figure 27(B), Figure 27(C), Figure The bars in Figures 27(E) and 27(F) are 5 μm.

[0298] As shown in Figures 26(E) to 26(J), the added MgF2 was detected from the SEM-EDX. -LiF nanoparticles melt upon heating and spread wet on the surface of lithium cobalt oxide particles. It was confirmed that this is the case. Also, as shown in Figures 27(D) to 27(F), one embodiment of the present invention EDX elemental mapping analysis of cathode active material particles revealed magnesium, nickel, and aluminum It was shown that nium is uniformly distributed. Nanoparticles composed of these doping elements are I couldn't see it.

[0299] ≪ICP-MS≫ In the synthesis of a positive electrode active material according to one embodiment of the present invention, the elemental ratio is Co:Mg:F=1:0.01 :0.023. Table 3 shows the addition using inductively coupled plasma mass spectrometry (ICP-MS). The results of the quantitative analysis of elements are shown. ICP-MS analysis was performed using an agilent 8900. As shown in Table 3, the elemental ratio of Co:Mg in the positive electrode active material particles of one embodiment of the present invention is 1 It was confirmed to be 0.0093.

[0300] [Table 3]

[0301] ≪EPMA≫ As shown in Table 4, even with an electron probe microanalyzer (EPMA), one of the present inventions In the cross-section of the positive electrode active material particles of the embodiment, the Co:Mg ratio was identified as 1:0.009. EPMA Analysis was performed using JXA-iHP200F (JEOL) at an acceleration voltage of 10kV. Bulk To analyze the elements, measurements were taken near the center of the particle cross-section.

[0302] [Table 4]

[0303] ≪XPS≫ However, X-ray photoelectron spectroscopy (XPS) shows that the edge of the positive electrode active material in one embodiment of the present invention The ratio of magnesium to fluorine to lute was significantly different from the amount added to the original LCO during synthesis. Magnesium and fluorine are highly distributed on the outermost surface of the particles of the positive electrode active material according to one embodiment of the present invention. It was found that the elemental ratio determined by XPS was Co:Mg:F = 1:0.93:0.53. .

[0304] Table 5 shows the original LCO measured by XPS analysis and the positive electrode active material according to one embodiment of the present invention, and Figure The chemical composition of the particle surface of the sample marked with an asterisk in section 2 is shown. XPS measurement was performed. Spectrometer equipped with AlX source (1486.6eV) (Quantera-SXM, ULVA) Recorded using C-PHI. All bond energies are for a 284.8 eV C1s bond. Calibration was performed using peaks.

[0305] [Table 5]

[0306] Figures 28 to 29(B) show the characterization of a positive electrode active material according to one embodiment of the present invention using XPS. Figure 28 shows the XPS wide scan spectra of the original LCO and the cathode active material according to one embodiment of the present invention. This is a positive electrode active material according to one aspect of the present invention, an LCO with magnesium and fluorine added, and a pre- A mixture of LCO, LiF and MgF2, MgF2 (reference sample), LiF ( The XPS narrow scan spectrum of F1s of the reference sample is shown in Figure 29(A), and the Mg1s spectrum is shown. The XPS narrow scan spectrum is shown in Figure 29(B).

[0307] As shown in Figure 29(A), the binding energy of F1s of the positive electrode active material in one embodiment of the present invention is Furthermore, this is different from MgF2 used as the additive element source. The binding energy of Mg1s in the positive electrode active material of one aspect of the invention suggests the presence of an oxyfluoride. The Mg1s peak of the positive electrode active material according to one embodiment of the present invention (1300 eV or more and 1308 eV or less) The maximum value in (1303.6 eV) is MgO (1303.3 eV) and MgF2 (13 It is located between the peaks of 0.6.3 eV.

[0308] ≪HAADF-STEM, NBED≫ Figure 25(E) shows a high-angle annular dark-field scanning transmission electron microscope image of the original LCO, including the particle surface layer. The HAADF-STEM image is shown. Figure 25(F) is enclosed by the dotted rectangle in Figure 25(E). This is an enlarged view of the region. Figure 25(G) shows region 1 and region marked in Figure 25(E). The nanobeam electron diffraction (NBED) pattern of region 2 is shown. Cross-sectional HAADF-STEM observation. NBED measurements were performed using a JEOL spherical aberration-corrected STEM JEM-ARM200F. Yes, it was done with an acceleration voltage of 200kV.

[0309] As shown in Figures 25(E) and (F), slight mixing of cations occurs near the surface. It was. Both region 1 and region 2 showed patterns indicating a layered rock salt type crystalline structure. It was revealed that the surface layer of CO particles has a layered rock salt structure similar to its internal structure.

[0310] Figure 25(H) shows a HAADF-STEM image including the particle surface of a cathode active material according to one embodiment of the present invention. Figure 25(I) is an enlarged view of the area enclosed by the dotted rectangle in Figure 25(H). J) shows the NBED patterns of regions 3 and 4 marked in Figure 25(H). Region 3 showed a rock salt type crystal structure, while region 4 showed a layered rock salt type crystal structure.

[0311] Note that the scale bars in Figures 25(E) through 25(I) all represent 3 nm. Figure 25 (G) and Figure 25(J) show the incident direction of the electron beam and the index of some spots. Figure 25 (J) shows spots (dashed circles) indicating a rock salt type structure and spots (real) indicating a layered rock salt structure. It includes a circle (with a line).

[0312] Using the dashed lines in Figure 25(I) as a guide, we can see the layered rock salt type crystal structure (Region I) and Coherent bonding of rock salt crystal structures (Region II) was suggested. Figure 25(H) And as shown in Figure 25(I), the inner side (also known as the bulk region) of the positive electrode active material according to one embodiment of the present invention. It has a layered rock salt structure, and in HAADF-STEM images, the contrast between the Co layer and the Li layer is visible. A crystalline structure was observed. Cation mixing was also observed. In the outermost region, a rock salt structure was observed with a thickness of 1 nm. (Indicated by electron diffraction spots enclosed in dashed circles), layered salt structure (enclosed in solid circles) This also includes (indicated by electron diffraction spots).

[0313] Of particular note is the area between Region I and Region II, as shown in Figure 25(I). Because the arrangement of atomic columns is continuous, the rock salt shell (Region II) is layered rock salt It is coherently bonded to the core (Region I). As seen in the XPS results, lithium is present in amounts comparable to cobalt and magnesium. Because it contains lithium ions, they are expected to pass through the shell.

[0314] In other words, lithium passes through sites in the rock salt crystal structure that are present after synthesis. The ions can pass through the shell. At this time, the proportion of lithium that occupies the cation sites is Li If the (Li+Co+Mg+Ni+Al) content is, for example, 20% or more, then the face-centered cubic lattice is Since the probability of insertion into the boundary is exceeded, it is thought that Li ions can be inserted and removed. Since this can also be a Li diffusion pathway, the above includes the proportion of cation vacancies (Li + cation vacancies). Even if the ) / (Li+Co+Mg+Ni+Al+cation deficiency) is 20% or more, Li ions are inserted. It is thought that it can be inserted and removed.

[0315] ≪STEM-EDX≫ Figures 30(A) to 31 show the energy-dispersive X-ray (ED) emission of a positive electrode active material according to one embodiment of the present invention. X) Elemental analysis is shown.

[0316] Figure 30(A) shows HAADF-STEM images and their corresponding Co, F, Mg, Ni, and This is a STEM / EDX elemental mapping analysis of Al. The bar is 5 nm. Figure 30(B) This is the depth profile of the elemental distribution. Figure 30(C) is an enlarged view of Figure 30(B). Figure 31 shows a wide-range HAADF-STEM image of the surface of positive electrode active material particles according to one embodiment of the present invention. And the corresponding STEM / EDX elemental mapping analysis of Co, F, Mg, Ni, and Al Yes. The bar is 50nm. Cross-sectional STEM-EDX analysis was performed using JED-2300T (JEO). This was done using L).

[0317] These findings revealed that F, Mg, and Ni are uniformly distributed across the entire outer surface. However, in this measurement, the presence of these in bulk was very small. Al is granular. Observed over a wide area from the surface. Near the surface of the positive electrode active material in one aspect of the present invention A clear gradient of added elements was observed. These observations suggest that during synthesis, layered rock salt is converted to rock salt structure. This suggests that a topotactic phase transition occurred to the structure of LCO. This is due to the movement of the added elements.

[0318] The distribution of additive elements in the particle surface layer of the positive electrode active material according to one embodiment of the present invention is as follows: This can be clarified. Firstly, Mg relative to lithium cobalt oxide 2+ Its solubility is approximately 0.5%. On the other hand, Al 3+ LiAl x Co 1-x Like O2, lithium cobalt oxide and solid solution It can be formed. Secondly, MgO, CoO, and NiO produce a solid solution with a rock salt structure. Therefore, Mg 2+ Ions and Ni 2+ Ions are reduced in the surface region during high-temperature heating. CoO region of lithium cobalt oxide particle surface formed by 2+ Io It may replace n. Therefore, the rock salt layer in the surface layer of lithium cobalt oxide contains It contains a considerable amount of Mg and Ni. On the other hand, the XRD shows that the c-axis is elongated and E From the PMA analysis, it is considered that most of the added magnesium is dissolved in the LCO particles. The distribution of the added elements is achieved by combining a molten salt of LiF and MgF2 with an appropriate heating step.

[0319] ≪Morphological and Structural Analysis at Each Stage of the Synthesis of the Cathode Active Material of One Aspect of the Present Invention≫ The detailed features of each step in the synthesis process of the cathode active material of one aspect of the present invention are described below.

[0320] For the evaluation of the structural characteristics, SEM-EDX, XPS, and XRD measurements were carried out at each stage of the synthesis process of the cathode active material of one aspect of the present invention. The analysis was performed at the following stages, which are marked with asterisks in the flowchart of the synthesis of the cathode active material of one aspect of the present invention shown in FIG. 2. - Original LCO - Preheated LCO - Mixture of preheated LCO, LiF, and MgF2 - LCO with added magnesium and fluorine - Mixture of LCO with added magnesium and fluorine, Ni(OH)2, and Al(OH)3 - Cathode active material of one aspect of the present invention

[0321]

[0321] <SEM-EDX Analysis> From the results of SEM-EDX (FIGS. 26(A) to 27(F)), the surface state of the particles in each step was as follows. The original LCO had many scratches and deposits on the particle surface. The surface of the preheated LCO particles was smoother than that of the original LCO. The particles of the mixture of preheated LCO, LiF, and MgF2 were sparsely decorated with nanoparticles of MgF2 and LiF. After the first heating step, the surface of the LCO with added magnesium and fluorine ​​​​​​​It became smooth, and nanoparticles containing Mg and F on the surface of LCO particles were observed by SEM-EDX It disappeared, and it was revealed that MgF2 and LiF melted on the LCO surface.

[0322] The surface of the particles of the mixture of LCO, Ni(OH)2, and Al(OH)3 to which magnesium and fluorine were added was uniformly coated with nanoparticles of Ni(OH)2 and Al(OH)3. The particle surface of the positive electrode active material according to one aspect of the present invention is smooth, unlike the mixture of LCO, Ni( OH)2, and Al(OH)3 to which magnesium and fluorine were added, and it was observed by SEM-EDX that it was uniformly coated with Mg, F , Ni, and Al.

[0323] <XPS analysis> The XPS measurement results are shown in FIGS. 28 to 29(B) and Table 5. From XPS, a large amount of magnesium and fluorine were detected from the mixture of preheated LCO, LiF, and MgF2. This is because, as can be seen from the SEM image, nanoparticles of MgF2 and LiF adhere to the LCO surface . In LCO to which magnesium and fluorine were added, the amount of magnesium detected after the first heating was larger than that before the first heating. This phenomenon is presumed to be due to an increase in the amount of magnesium in the XPS detection region at a depth of about 5 nm from the surface . This increase is attributed to the melting and diffusion of magnesium on the surface of lithium cobaltate particles due to the effect of molten fluoride salt . The detected amount of fluorine was less than that in the previous step, which is considered to be because a part of LiF melted and volatilized . A very large amount of nickel and aluminum was detected from the mixture of LCO, Ni (OH)2, and Al(OH)3 to which magnesium and fluorine were added . This result is, as can be seen from the SEM image, Ni(OH)2 and Al(OH)3 This is presumably because the nanoparticles cover the particle surface. In the cathode active material of one embodiment of the present invention, compared with the mixture of LCO, Ni(OH)2, and Al(OH)3 to which magnesium and fluorine are added, since the detected amounts of nickel and aluminum were small, it is considered that nickel and aluminum form a solid solution in the surface layer portion of the lithium cobaltate particles. Furthermore, since the detected amount of magnesium is larger than the detected amounts of nickel and aluminum, it can be seen that magnesium is located on the outermost surface of the LCO particles, and nickel and aluminum are located inside thereof.

[0324] Figures 29(A) and 29(B) show the binding energies of F and Mg. The binding energies of F1s and Mg1s in the mixture of preheated LCO, LiF, and MgF2 indicate the presence of MgF2. However, the LCO to which magnesium and fluorine are added shows different binding energies, suggesting the presence of an O-Mg-F bond. The O-Mg-F bond was also maintained in the cathode active material of one embodiment of the present invention to which Ni(OH)2 and Al(OH)3 were added.

[0325] <XRD Analysis> Table 6 shows the results of Rietveld refinement of the powder XRD pattern. The lattice constant of the preheated LCO is smaller than that of the original LCO, which is presumably because the mixing of cations decreased and the crystallinity improved. The c-axis length of the LCO to which magnesium and fluorine are added increased compared with the mixture of preheated LCO, LiF, and MgF2. This is because Mg with a larger ionic 3+ radius than Co was substituted for the cobalt site, or Mg 2+ with an ionic + radius similar to that of Li has a radius of Mg 2+ ​​The lithium site is replaced, and the adjacent cobalt is used for charge compensation. This suggests that the valency changed from 3 to 2. The positive electrode active material of one embodiment of the present invention is also Furthermore, the elongated c-axis was maintained. This indicates that the surface of the positive electrode active material in one embodiment of the present invention was XPS As shown, the positive electrode of one aspect of the present invention is not only coated with a large amount of magnesium, but also This suggests that the bulk material of the active material is also doped with magnesium.

[0326] [Table 6]

[0327] <Electrochemical properties> Half Cell Figures 32(A) and 32(B) show the original LCO in a half-cell and the present invention. Figure 32 shows the cycle characteristics of a positive electrode having a positive electrode active material of the embodiment. A coin-shaped electrode having the original LCO and an electrode having the positive electrode active material according to one aspect of the present invention. This shows the cycle performance in the fuchel. Figure 32(A) shows 2.5-4.6V (vs. Li + / Li ) range, Figure 32(B) is 2.5-4.7V (vs. Li + In the voltage range of / Li) , charging and discharging of a half cell using the original LCO and a positive electrode having a positive electrode active material according to one aspect of the present invention This is the electric cycle performance. Figure 33(A) shows the different cycle performance under the conditions shown in Figure 32(A). Figure 33 shows the charge-discharge curves of the original LCO and the positive electrode active material according to one embodiment of the present invention. B) The rate performance of a half-cell using the original LCO and the positive electrode active material of one aspect of the present invention Yes. In Figures 32(A) and 32(B), the white circles represent the positive electrode active material of one embodiment of the present invention. The black circles indicate the discharge capacity of the positive electrode active material according to one embodiment of the present invention, and the white squares indicate the ion efficiency. The black square represents the Coulomb efficiency of the original LCO, and the black square represents the discharge capacity of the original LCO. Figure 35(A) The same applies to Figures 39(A) and 39(B).

[0328] When using a commonly used electrolyte, the positive electrode active material of one aspect of the present invention is better than the original LCO. It also showed a considerably high capacity retention rate. Specifically, the positive of one aspect of the present invention after 100 cycles The capacity retention rate of the extremely active material is 2.5-4.6V (vs.Li + / Li) is 96.4% (20 5.2mAh / g), 2.5-4.7V (vs. Li) + / Li) is 72.7% (160. This is 9mAh / g, which is much higher compared to the original LCO. One aspect of the present invention The high Coulomb efficiency observed during the cycle with the positive electrode active material indicates that oxidative electrolyte decomposition is occurring on the surface. This suggests that it was effectively suppressed by the coating layer.

[0329] The charge / discharge curve shown in Figure 33(A) represents the average discharge voltage of the positive electrode active material in one embodiment of the present invention. This indicates that it remains high even after 100 cycles. On the other hand, with increasing voltage polarization, the original The average discharge voltage of the LCO decreased. Also, as shown in Figure 33(B), at each discharge rate... Furthermore, the positive electrode active material according to one embodiment of the present invention showed superior rate performance compared to the original LCO. A positive electrode active material according to one aspect of the present invention, as shown in Figure 34, has a practical level of high loading capacity (20 mg / cm 2 Even with this, high-rate charging and discharging was possible. In Figure 33(B), the white circles indicate the main power The black squares indicate the discharge capacity of the original LCO, representing the discharge capacity of the positive electrode active material in one aspect of the image.

[0330] In the initial charge-discharge cycle of the positive electrode active material according to one aspect of the present invention, the cell resistance decreases and the discharge capacity This increased. This phenomenon is due to the formation of a solid electrolyte interphase (SEI) on the surface of lithium cobalt oxide. This is due to the fact that magnesium diffused into the structure of lithium cobalt oxide. ru.

[0331] Typical electrolytes are 4.7V (vs.Li + Due to the high cutoff voltage of / Li, Considering the possibility of misinterpretation, a modified fluorine-based electrolyte was used instead of a general electrolyte. Cells were fabricated. In addition, to mitigate the effects of electrolyte decomposition, a high charge / discharge rate and low quality were used. Cycle performance was evaluated using electrodes with varying loads.

[0332] Figure 35(A) shows a positive electrode having a positive electrode active material according to one embodiment of the present invention using a fluorine-based electrolyte. Half-cell with positive electrode having original LCO, voltage range 2.5-4.7V (vs. Li + The cycle performance at / Li) is shown. Figure 35(B) is shown under the conditions shown in Figure 35(A). The charge-discharge curves of the original LCO and the positive electrode active material of one aspect of the present invention in different cycles. The electrolyte is FEC / MTFP (volume ratio 2:8) in which 1M LiPF6 is dissolved. A mixture containing 5 wt% PS was used. Cycle performance tests were conducted in sections 2.5-4. 7V voltage range (vs. Li + With Li, the current is 200mA / g, and the final current is 40mA / g. CCV charging and CC discharge at 200 mA / g were performed. A 1-minute rest period was observed after each charge / discharge step. A time limit was set. The measurement environment was set at 25°C in all cases.

[0333] This approach allows for 200mA / g, voltage range 2.5-4.7V (vs. Li + / Li) and after 100 cycles it is 88.5 A high capacity retention rate of % (191.5mAh / g) was achieved.

[0334] The half-cell was fabricated as follows: 95 wt% active material, carbon carbamide as conductive additive. Denka Black (registered trademark, manufactured by Denka Co., Ltd.) 3wt%, with polypropylene as a binder. An LCO cathode was prepared by mixing 2 wt% vinylidene fluoride. The weighed powder was N-methyl Mix in -1,2-pyrrolidone (NMP, 99.9%, manufactured by Tokyo Chemical Industry Co., Ltd.) until uniform. A slurry was prepared. This slurry was then used to collect current from aluminum foil using a doctor blade. It was applied to the body. The NMP solvent was dried in a forced-convection drying oven at 80°C for 0.5 hours. The quality of the mass load is basically about 7 mg / cm³. 2 Although controlled, the data in Figures 33 and 35 In Ta, the concentration is approximately 20 mg / cm³. 2 and approximately 3 mg / cm³ 2 It was controlled to that extent. The fabricated positive electrode, As the counter electrode, lithium metal foil (0.6 mm thick, 99.9% purity, manufactured by Honjo Metal), Separator Using polypropylene (PP) as the substrate and an electrolyte, the process is carried out in an argon-filled glove box. I assembled an in-type half-cell (CR2032).

[0335] Two types of electrolyte were used for the half-cells. One type was ethylene carbonate / diethyl carbonate. Dissolve LiPF6 in a 1M solution of vonate (EC / DEC = volume ratio 3:7) and add it. A common electrolyte solution with 2 wt% vinylene carbonate (VC) added as an agent. The other type is F Luoroethylene carbonate / methyl 3,3,3-trifluoropropionate (FEC / MTFP (volume ratio 2:8) is dissolved in LiPF6 to a volume of 1M, and 1, This is a fluorine-based electrolyte with 5 wt% 3-propanesultone (PS) added. Unless otherwise specified. We used commonly available electrolytes as much as possible.

[0336] Charge / discharge measurements were performed using the TOSCAT-3100 battery testing system (manufactured by Toyo System Co., Ltd.). The test was conducted using a temperature-controlled chamber at 25°C. The half-cell cycle performance test was performed as follows: 5-4.6V or 2.5-4.7V (vs. Li + 100mA in the voltage range of / Li) Constant current-constant voltage (CCCV) charging of / g, final current of 10mA / g, and 100mA / A constant current (CC) discharge of g was performed. Using the maximum discharge capacity obtained during the cycle test, The capacity retention rate after 100 cycles was calculated.

[0337] In the discharge rate performance test shown in Figure 33(B), constant current-constant voltage at 100 mA / g ( CCCV charging is performed, using a final current of 10mA / g, followed by a voltage of 2.5-4.7V. CC discharge was performed within the range (vs. Li + / Li). CC discharge current is as follows (5 cycles) The following values ​​were varied for each cycle: 40mA / g, 100mA / g, 200mA / g, 400mA / g 600mA / g, 1000mA / g, 2000mA / g, 100mA / g. Each charge / discharge... A 10-minute break was provided after each step.

[0338] In the experiment shown in Figure 34, constant current constant voltage (CCCV) charging was performed at 40 mA / g, and 4m A discharge ray is used, which uses the final A / g current and then performs CC discharge in the voltage range of 2.5 to 4.7V. A test was conducted (vs. Li + (Li). The CC discharge current is as follows every 5 cycles Variables: 40, 100, 200, 400, 600, 1000, 40 mA / g. Each charge / discharge. A 10-minute break was provided after the electric step.

[0339] ≪Full Cell≫ To evaluate the electrochemical performance under more practical conditions, a positive electrode active material according to one aspect of the present invention is used. Using a positive electrode and a negative electrode made of commercially available graphite, a pouch-type full cell with the same configuration as a commercially available product is produced. I made it.

[0340] The positive electrode was fabricated in the same way as in the half-cell case. The negative electrode was made using artificial graphite (MCM) as the active material. B: meso carbon micro beads graphite G10, Linyi Gelon Lib Co., Ltd.) 96 wt%, as a conductive additive. Vapor-phase grown carbon nanofiber (VGCF(registered trademark)-H, Showa Denki o Co) 1 wt%, and as a thickening agent, sodium carboxymethylcellulose (CMC (Manufactured by Kishida Chemical Co., Ltd.) 1 wt%, Styrene-butadiene rubber (SBR, T) as binder. RD2001 (manufactured by JSR Corporation) was used at 2 wt%.

[0341] The weighed negative electrode active material, conductive additive, thickener, and binder powders are mixed with distilled water and then slurred. Lee was prepared and coated onto a copper foil current collector. The mass loads of the positive and negative electrodes were 10.6 each. mg / cm 2 and 7.6 mg / cm³ 2 The dimensions are 41mm x 50mm and 45mm x It was 53mm. The cell design had a positive electrode to negative electrode capacity ratio of approximately 80%, and the positive electrode to negative electrode capacity was They achieve 200mAh / g and 300mAh / g respectively, with a total cell capacity of 40mAh. The goal was to assemble the pouch-type full cell in an argon-filled glove box. This was done using a stacking process. In this process, the negative and positive electrodes were coated on one side. Electrode sheet, polypropylene separator (PP), 1M LiPF6 FEC / MTFP An electrolyte solution dissolved in a volume ratio of 2:8 was used.

[0342] For the full cell prepared as described above, use 3.0-4.5V (vs. graphite) or 3. CCCV charging in the voltage range of 0-4.6V (vs. graphite) (40mA / g, final current 4mA). Cycle performance tests were conducted using A / g and CC discharge (40mA / g). A one-minute rest period was provided after each step.

[0343] Figure 36 shows the electrochemical performance of the pouch-type full cell at 25°C. Figure 36(A) is 3 Figure 36(B) shows one embodiment of the present invention in the voltage range of 0-4.5V, 3.0-4.6V. The cycle performance (vs. graphite) of a pouch-type full cell using a cathode with the positive electrode active material is as follows: ru.

[0344] The energy density retention rate of each full cell after 500 cycles at 25°C is as follows: voltage range 3.0 Up to 4.5V: 90.3% (656.8Wh / kg), 3.0 to 4.6V: 75.8% The value was 593.4 Wh / kg (vs. graphite). Using a positive electrode active material according to one embodiment of the present invention The full cell was used in previous research on doping and coating of LCO at high voltage ( For example, compared to Non-Patent Documents 7, 12, and 17, it is remarkably stable. It demonstrated excellent cycle performance.

[0345] <Analysis of the positive electrode active material of one embodiment of the present invention and the original LCO after cycle testing> Figure 37(A) shows the original LCO and one embodiment of the present invention in the discharge state after 100 cycles. The ex situ XRD pattern of the positive electrode containing the positive electrode active material is shown. Figure 37(B) is 2θ Figure 37(C) shows an enlarged view of the 18°-19.5° range, and Figure 37(C) shows an enlarged view of the 44.5°-45.5° range. Enlarged view.

[0346] For measuring the original LCO and the positive electrode active material of one aspect of the present invention, commonly used in Figure 37. A coin-type half-cell was used with the specified electrolyte. Discharge state after 100 cycles Ex situ of the original LCO in the state and the positive electrode having the positive electrode active material of one aspect of the present invention For XRD, the voltage range is 2.5-4.7V (vs. Li + / Li) and CCCV Using charging (40mA / g, final current 10mA / g) and CC discharge (40mA / g) The cell was cycled.

[0347] XRD measurements were performed using a Bruker D8 ADV equipped with CuKα (λ=1.5406Å). The analysis was performed using an ANCE diffractometer. The powder sample was scanned in a 15°-90° scan range (2θ), 0 Analysis was performed with a step size of 0.005° and a scan speed of 0.1 seconds / step. Rietveld precision Densification is performed using DIFFRAC TOPAS V6 software (Bruker). The measurements were performed under the same conditions. Subsequent ex situ XRD measurements were also performed under the same conditions.

[0348] As shown in Figure 37, in the discharge state after 100 cycles, the original LCO's ex si The tu XRD pattern showed a broad XRD peak, indicating low crystallinity.

[0349] The XRD pattern shown in Figure 37 was generated using DIFFRAC.EVA as the background. And the pattern with the peaks originating from CuKα2 removed. Background removal conditions 25 Curvature and 1e -5 Set to Threshold.

[0350] Lithium cobalt oxide 003 is around 2θ = 19° (in the range of 18° to 19.5°). It is known that a peak occurs. The full width at half maximum of the 003 peak in the original LCO (Honmei Unless otherwise specified in the detailed specifications, the full width at half maximum (FWHM) refers to the total width at half maximum before the charge-discharge cycle test. The initial reading was 0.0325°, but after 100 charge-discharge cycle tests it was 0.1836°. The angle became significantly broader and shifted to the lower angle side. Also, lithium cobalt oxide 10 For 4, a peak occurs around 2θ = 45° (in the range of 44.5° to 45.5°). It is known that the full width at half maximum of the 104 peak in the original LCO was 0 before the charge-discharge cycle test. The initial reading was 0.0644°, but after a similar test, it became broader again at 0.1594°.

[0351] However, the positive electrode active material of one aspect of the present invention shows a sharp peak and remains high even after 100 cycles. This demonstrated that the crystallinity was maintained. The 003 peak of the positive electrode active material in one embodiment of the present invention The full width at half maximum (FWHM) was 0.0333° before the charge-discharge cycle test, and after 100 charge-discharge cycles... Even after the crunch test, the peak is still sufficiently sharp at less than 0.10°, specifically 0.0515°. Furthermore, the full width at half maximum of the 104 peak was 0.0636° before the charge-discharge cycle test, and similarly... Even after the test, the sharpness was still below 0.11°, specifically 0.0646°, which is sufficiently sharp.

[0352] Figures 38(A) to 38(H) show the original LCO and the present invention in the discharge state after cycling. SEM images of one embodiment of the positive electrode active material are shown. Figures 38(A) and 38(B) show the results after 5 cycles. Figures 38(C) and 38(D) show the original LCO and the SEM of the original LCO after 50 cycles. This is an image. Figures 38(E) and 38(F) show the positive electrode active material of one embodiment of the present invention after 5 cycles. Figures 38(G) and 38(H) show the quality of the positive electrode active material of one embodiment of the present invention after 50 cycles. This is an SEM image. Figure 39(A) shows the SEM image after 5 cycles, taken at 25°C, 2.5-4°C. 7 V voltage range (vs. Li + The original LCO in / Li and the positive electrode activity in one aspect of the present invention This is the cycling performance of the material. Figure 39(B) shows the SEM image after 50 cycles at 25°C. Voltage range of 2.5-4.7 V (vs. Li + The original LCO in / Li) and the present invention 1 This is the cycle performance of the positive electrode active material in each configuration. The scale bars are shown in Figures 38(A) and 38(C). Figures 38(E) and 38(G) are 50 μm, Figures 38(B), 38(D), and 38(F) are 50 μm. Figure 38(H) is 5 μm. In Figures 39(A) and 39(B), the discharge capacity is 10 m Coulomb efficiencies for measurement points below Ah / g are not plotted.

[0353] As shown in Figures 38(A) to 38(D), the SEM view of the original LCO after the cycle test. During the inspection, a small number of cracks were observed in the discharge state after 5 cycles. These cracks were particularly It was clearly observed near the grain boundary. In the discharge state after 50 cycles of the original LCO, the crack was It increased and grew larger. In one embodiment of the present invention, in the discharge state after 5 cycles, No racks were observed. After 50 cycles of discharge, only a few small cracks were visible. It was done.

[0354] In addition, the original LCO after 50 cycles in a voltage range of 2.5-4.7V and one aspect of the present invention HAADF-STEM images and NBED patterns of the positive electrode active material were obtained. Figure 40(A) The HAADF-STEM image of the original LCO particle surface, Figure 40(B), shows a ma in Figure 40(A). The NBED patterns of the marked regions 1 to 3 are shown. Region 1 is a rock salt type crystal structure, Region 2 showed a spinel-type crystal structure, while region 3 showed a layered rock salt-type crystal structure.

[0355] Figure 40(C) shows a HAADF-STEM image of the surface layer of positive electrode active material particles according to one embodiment of the present invention. In 40(D), the NBED patterns of regions 4 and 5 marked in Figure 40(C) are shown. As shown, region 4 showed a rock salt type crystal structure, and region 5 showed a layered rock salt type crystal structure. The scale bar in Figures 40(A) and 40(C) represents 3 nm.

[0356] Figure 40(B) shows that the original LCO has a surface layer of spinel and rock salt facies approximately 3 nm thick. This demonstrates that it has been accomplished. Importantly, this is shown in Figures 40(C) and 40(D). As shown above, even after 50 cycles, the outermost surface of the positive electrode active material in one embodiment of the present invention is approximately 1 nm thick. It maintains its rock salt structure.

[0357] The formation of spinel and then rock salt phases occurred in the deteriorated original LCO surface. This is because oxygen was released from there. However, the surface layer of the positive electrode active material in one aspect of the present invention contains magnesium Due to the high concentrations of nesium, nickel, and aluminum, under high lithium desorption conditions The release of oxygen from the LCO surface was suppressed, inhibiting the formation of spinel regions.

[0358] <Crystal structure analysis of a positive electrode active material according to one embodiment of the present invention in a high lithium desorption state> ≪ex situ XRD≫ To clarify the mechanism of performance improvement, we performed structural analysis during high-voltage cycling.

[0359] Normally, an LCO undergoes a phase transition from the O3 phase to the H1-3 phase when charged up to 4.55V. It is known that (Li x In CoO2, x < 0.3). This structural change is LCO at high voltage. This reduces the capacity retention rate. Excellent electrification of positive electrode active material according to one embodiment of the present invention at high voltage. The scientific performance is thought to be strongly correlated with the suppression of this phase transition, and the charge extracted from the half-cell Ex situ XRD measurements were performed on the completed positive electrode.

[0360] Figures 41 and 42 show the original LCO or one embodiment of the present invention in various cycles. Figure 41(A) shows the ex situ XRD pattern of the positive electrode containing the positive electrode active material. This is the original LCO's ex situ in the first and fifth charging states up to 4.7V. XRD pattern, Figure 41(B) is an enlarged view of the 2θ range between 18° and 21°, Figure 41(C) This is an enlarged view of the 2θ range between 42° and 48°. Figure 42(A) shows the first measurement up to 4.7V. , ex of the positive electrode active material of one embodiment of the present invention in the 2nd, 5th and 50th charging states Situ XRD pattern, Figure 42(B) is an enlarged view of the 2θ range between 18° and 21°. Figure 42(C) is an enlarged view of the 2θ range between 42° and 48°. The reference XRD pattern is: Li 0.35 CoO2 (O3 phase) (Non-Patent Document 18 and ICSD Collection Code 1) 72912), Li 0.12 CoO2H1-3 phase (Non-Patent Document 19), and the Specified This is the O3' phase described below. In Figures 41(A) to 44(C), the diamond shape (◇) represents the decongestant phase. Lithium-ionized conventional O3 phase, triangle (△) represents the H1-3 phase, and circle (●) represents the O3' phase. This is the peak.

[0361] In order to perform the ex situ XRD measurements shown in Figures 41(A) to 44(C), A coin-type half-cell using the electrolyte commonly used was employed. Figure 41(A) to In the case of the original LCO and the positive electrode having the positive electrode active material of one aspect of the present invention, once For the first, second, fifth, or 50th charge, C was used before the ex situ XRD measurement. It was charged to 4.7V at C (10mA / g). Before the 2nd, 5th, and 50th charges, CCCV charging (100mA / g, final current 10mA / g) and CC discharge (100mA / g) 2.5-4.7V (vs. Li + Within the voltage range of / Li, the cell is run 1, 4, and 49 times. I made it happen.

[0362] Then, in a glove box filled with argon, the positive electrode seal of the charged or discharged cell... The positive electrode sheet was removed and prepared for ex situ XRD measurement. After cleaning with a nitrate to remove the electrolyte and drying, it is fixed to a flat glass substrate with double-sided tape. These samples were placed in an argon glove box and sealed in an airtight sample holder (part number: A1 The sample was sealed in 00B33 and XRD measurements were performed in an argon atmosphere. Scan range (2θ) 1 The settings were 5° to 75°, step size 0.01°, and scan speed 1.0 seconds / step.

[0363] As shown in Figures 41(A) to 41(C), when the original LCO is initially charged at 4.7V The charging capacity is 239.4mAh / g, and the lithium concentration (Lix CoO2) becomes x = 0.13 The formation of the H1-3 phase was confirmed by ex situ XRD.

[0364] Also, Figure 43 shows the positive electrode with the original LCO in a charged state of 4.6V or 4.7V. The ex situ XRD pattern is shown. Figure 43(A) is 4.6V at 10mA / g or Ex situ XRD pattern of the positive electrode with original LCO during initial charging at 4.7V Figure 43(B) is an enlarged view of the 2θ range between 18° and 21°. Figure 43(C) This is an enlarged view of the 2θ range between 42° and 48°.

[0365] As shown in Figures 43(A) to 43(C), the initial charge is up to 4.6V, and the charging capacity 224.6mAh / g(Li x Even when the x of CoO2 becomes low (0.18), H1 -3 phase formation was observed.

[0366] As shown in Figure 41, the sample that underwent its fifth charge at 4.7V was exposed to high voltage. This appears to have damaged the surface layer of the original LCO, making lithium diffusion difficult, thus filling The capacitance was 145.6 mAh / g (x=0.47). The original LCO had reversible degradation. Because it is intense, Li x The phase transition from the O3 phase to the H1-3 phase in CoO2 at x < 0.3 is observed. It wasn't noticed.

[0367] Figures 42(A) to 42(C) show a positive electrode having a positive electrode active material according to one embodiment of the present invention. The itu XRD pattern is shown. Figure 42(A) shows the first and second measurements up to 4.7V. Ex situ of the positive electrode active material of one embodiment of the present invention in the 5th and 50th charging states XRD pattern, Figure 42(B) is an enlarged view of the 2θ range between 18° and 21°, Figure 42(C) ) is an enlarged view of the 2θ range of 42° to 48°. Figures 44(A) to 44(C) are 4 A positive electrode active material according to one embodiment of the present invention in a charged state of 0.5V, 4.6V, or 4.7V. The ex situ XRD pattern of the positive electrode is shown.

[0368] Figure 42 shows a positive electrode active material according to one embodiment of the present invention during the first charge up to 4.7V. The ex situ XRD pattern of the pole is shown, which is 220.1mAh / g(Li x This corresponds to the charging capacity of CoO2 (x=0.20). Surprisingly, it charges up to 4.7V. The ex situ XRD pattern of the positive electrode active material according to one embodiment of the present invention is two O3 phases. The superposition of these diffraction patterns is shown, and no diffraction pattern corresponding to the H1-3 phase was observed. .

[0369] The diffraction pattern of the first O3 phase shows peaks at the low-angle side, 2θ = 19.0° and 45.3°. Furthermore, the diffraction pattern of the second O3 phase shows peaks at high angles 2θ = 19.2° and 45.5°. As shown, the first O3 phase corresponds to the conventional delithified O3 phase. This classification is shown in Figure 4. As shown in 4, the diffraction peak continuously shifts from 4.5V to 4.7V during the charging state. Based on the above. Figure 44(A) shows charging to 4.5V, 4.6V, or 4.7V at 10mA / g. This is an ex situ XRD pattern of a positive electrode having a positive electrode active material according to one aspect of the present invention. Figure 44(B) is an enlarged view of the 2θ range between 18° and 21°. Figure 44(C) is a 2θ range This is an enlarged view of an area between 42° and 48°.

[0370] The second O3 phase is considered to be a different phase with a smaller unit cell volume and the same symmetry as the O3 phase. This is referred to as the "O3' phase" in this specification.

[0371] The second charge capacity is 215.4mAh / g(Li x In CoO2, x = 0.21. The second charge was slightly smaller than the first charge. The area intensity ratio of the folded peak increased, and the peak position shifted to the higher angle side. The shift to indicates a decrease in the volume of the unit cell and the lithium concentration in lithium cobalt oxide. This suggests a decrease in the electrochemically observed capacitance (1st time: x=0.20, The lithium concentration and spearhead in the first and second charges estimated from the second charge (x=0.21) Shielding. During the initial charge, the charge can be confirmed not only by lithium desorption but also by the Coulomb efficiency. It should be noted that SEI can also be consumed by the decomposition of the electrolyte, which is accompanied by the formation of SEI. .

[0372] Therefore, in the first charge, the actual lithium concentration is the lithium concentration estimated from the capacity. The value is higher than (x=0.20) and likely higher than the actual lithium concentration during the second charge. After the fifth charge with a capacity of 225.3mAh / g (x=0.18), the O3' phase Appearing as a single phase, the diffraction peak becomes higher as the charging capacity increases from the second charge onwards. It shifted to a different angle.

[0373] After the 50th charge, with a capacity of 214.5mAh / g (x=0.22), the H1-3 phase... A weak, related diffraction peak was detected, but the O3' phase remained.

[0374] ≪dQ / dV curve≫ Figure 45 shows one embodiment of the present invention in the 1st, 5th, and 50th cycles. The dQ / dV curve of the positive electrode active material is shown. The dQ / dV measurement was performed within the voltage range of 2.5-4.7 The measurement was performed using a half-cell with a voltage of 10 mA / g and a current of 10 mA / g, at a temperature of 25°C. Before dQ / dV measurement. , 2.5-4.7V (vs. Li + In the voltage range of / Li, the 5th or 50th measurement Before the final charge, CCCV charging (100mA / g, final current 10mA / g) and CC discharge ( The cells were cycled 4 or 49 times at 25°C using 100mA / g. Each charge... A 10-minute rest period was provided after the discharge step. In the first cycle, a large voltage polarization occurred. Observed, this is consistent with the low capacitance in the first cycle of the cycle performance test. Voltage component The poles became smaller after 5 cycles and remained small even after 50 cycles. One aspect of the present invention The positive electrode active material exhibits the following characteristics in the dQ / dV curves at cycles 5 and 50: charge / discharge Both voltages showed a reversible peak above 4.5V at 25°C.

[0375] As shown in Figure 45, the dQ / dV curve of a positive electrode active material according to one embodiment of the present invention is as follows: charging and discharging The voltage shows a reversible peak above 4.5V, indicating a sustained phase transition from the O3 phase to the O3' phase. It was shown to be reversible.

[0376] ≪Rietveld Refinement≫ The lattice constants of the O3' phase are detailed in Tables 7 and 8, for the first and fifth charges. The XRD pattern of the electric cycle was determined using Rietveld refinement. Compared to the values ​​reported in previous studies (Non-Patent Document 18, etc.) on the modified O3 phase, the present invention In one embodiment, the lattice constant of the c-axis of the positive electrode active material is remarkably small.

[0377] [Table 7]

[0378] [Table 8]

[0379] The equivalent isotropic temperature factor (Beq) used in the Rietveld refinement was assumed to be constant, with Li = 1. The values ​​were set to 10⁵; Co=0.371; O=0.552. For calculating the site occupancy of Li ions... The charge capacity before ex situ XRD measurement was used. Sites of O ions and Co ions. The occupancy rate was set to 1.

[0380] ≪Additive Element Distribution≫ In this specification, in one embodiment of the present invention, the positive electrode active material is provided by the effect of magnesium as a pillar. It is assumed that the displacement of the CoO2 slab will be suppressed. To test this hypothesis, ML CO, MF-LCO, FA-LCO, FN-LCO, FNA-LCO, and the embodiment of the present invention The cycle performance of a positive electrode with a specific positive electrode active material was measured using ex situ XRD in a high-charge state. It was evaluated in combination with the standard.

[0381] Figures 46(A) to 47(B) show M-LCO, MF-LCO, and one embodiment of the present invention. The ex situ XRD pattern and cycle performance of the positive electrode active material are shown. Figure 46(A) is 4 M-LCO, MF-LCO, and positive electrode according to one embodiment of the present invention, charged to 4.6V at mA / g This is the ex situ XRD pattern of the positive electrode containing the active material. Figure 46(B) shows the 2θ range. Figure 46(C) is an enlarged view of the 18°-21° range, and Figure 46(C) is an enlarged view of the 2θ range 42°-48°. 7(A) is 2.5-4.6V (vs. Li +Cycles at 25 °C within the voltage range of (vs. Li Performance, Figure 47(B) shows 2.5 - 4.7 V (vs. Li + / Li) within the voltage range at 25 °C of the cycle performance.

[0382] Figures 48(A) to 49(B) show the ex situ XRD patterns and cycle performance of the cathode active materials of one embodiment of the present invention, FN-LCO, FA-LCO, FNA-LCO, and Figure 48(A) shows the ex situ XRD pattern of the cathode having FN-LCO, FA-LCO, FNA-LCO, and the cathode active material of one embodiment of the present invention charged to 4.6 V at 4 mA / g. Figure 48(B) is an enlarged view in the 2θ range of 18° - 21°, and Figure 48(C) is an enlarged view in the 2θ range of 42° - 48°. Figure 49(A) shows the cycle characteristics at 25 °C within the voltage range of 2.5 - 4.6 V (vs. Li / Li ), and Figure 49(B) shows the cycle performance at 25 °C within the voltage range of 2.5 - 4.7 V (vs. L + / Li ) and Figure 49(B) shows the cycle performance at 25 °C within the voltage range of 2.5 - 4.7 V (vs. Li i + / Li). In Figures 47(A), 47(B), and 49(A) to 52(B), the filled markers indicate the discharge capacity , and the unfilled markers indicate the Coulomb efficiency. The Coulomb efficiency of the measurement points where the discharge capacity is less than 25 mAh / g is not plotted. For the ex situ XRD measurement of the cathodes having M-LCO, MF-LCO, FN-LCO, FA-LCO, FNA-LCO, and the cathode active material of one embodiment of the present invention, CCCV charging (40 mA / g, final current 10 mA / g) and CC discharging (40 mA / g) were cycled once in the voltage range of 2.5 -

[0383] 4.5 V (vs. Li / Li). The cell was ex sit 4.5 V voltage range with CCCV charging (40 mA / g, final current 10 mA / g) and CC discharging (40 mA / g) for one cycle (vs. Li + / Li). The cell was ex sit It was charged at CC (4 mA / g) up to 4.6 V before XRD measurement.

[0384] Only MF-LCO and the cathode active material of one embodiment of the present invention showed excellent cycle performance and did not show the H1- 3 phase. Therefore, the formation of the O3’ phase is due to the introduction of magnesium by treatment with molten fluoride salt.

[0385] To investigate the effect of only LiF, the cycle characteristics of only heated LCO, F-LCO, FNA-LC O, and NA-LCO were measured.

[0386] The cycle performance of the original LCO, only heated LCO, and F-LCO at 25 °C in the voltage range of 2.5 - 4.6 V (vs. Li + / Li) is shown in Fig. 50(A), and the cycle performance in the voltage range of 2.5 - 4.7 V (vs. Li + / Li) is shown in Fig. 50(B).

[0387] The cycle performance of NA-LCO, FNA-LCO, and the cathode active material of one embodiment of the present invention at 25 °C in the voltage range of 2 [[ID=3I]] .5 - 4.6 V (vs. Li + / Li) is shown in Fig. 51(A), and the cycle performance in the voltage range of 2.5 - 4.7 V (vs. Li + / Li) is shown in Fig. 51(B). The Coulomb efficiency of the measurement points with a discharge capacity of less than 25 mAh / g is not plotted.

[0388] As shown in Figs. 50(A) to 51(B), the improvement in charge-discharge cycle characteristics by adding LiF without MgF2 was small.

[0389] As shown in Fig. 6, in a highly delithiated state, the presence of magnesium substituted in the lithium layer provides structural support and the slippage of the CoO2 layer and the phase transformation from the O3 phase to the H1-3 phase This indicates that it prevents deterioration. Furthermore, the slippage probably starts on the surface of the LCO, and then The presence of a magnesium-rich rock salt region in the surface layer of the positive electrode active material in one aspect of the present invention This may be suppressed. As a result of the suppression of layer slippage, the positive electrode active material of one aspect of the present invention This includes SEM (Figures 38(E) to 38(H)) and STEM (Figure 40(C)) after cycling. As seen in ), the surface layer is less prone to degradation and lithium diffusion is not inhibited, resulting in good It is possible to show the rate and cycle characteristics.

[0390] MFN-LCO and MFA-LCO are produced by a process similar to that of the positive electrode active material in one aspect of the present invention. MgF2-LiF-Ni(OH)2 and MgF2-LiF-Al(OH)3 were added to each. It was synthesized.

[0391] Original LCO, MFN-LCO, MFA-LCO, and positive electrode active material according to one aspect of the present invention Voltage range of 2.5-4.6V at 25℃ (vs. Li + Cycle performance in / Li Figure 52(A) shows the voltage range of 2.5-4.7V (vs. Li + Cycle performance at / Li) This is shown in Figure 52(B).

[0392] As shown in Figures 52(A) and 52(B), nickel is present along with magnesium and fluorine. The sample containing both aluminum and other materials showed the best volume retention rate. This positive electrode active material according to one aspect of the present invention has a very high Coulomb efficiency (for example, cutoff current). When comparing at a pressure of 4.7V in the third cycle, the positive electrode active material according to one embodiment of the present invention achieved 99.79%. This is due to MFN-LCO showing 99.48% and MFA-LCO showing 99.34%. .

[0393] As described above, in this specification, a molten fluoride salt is used as a reaction accelerator. This enabled magnesium diffusion and doping from the LCO particle surface to the bulk. In addition, The excess magnesium covered the surface layer of the positive electrode active material particles in one aspect of the present invention. The invention effectively prevents harmful phase changes to the H1-3 phase, especially at a charging voltage of 4.7V. Ta.

[0394] Furthermore, ex situ XRD analysis of the positive electrode active material according to one embodiment of the present invention at 4.7V This revealed the formation of a different O3 phase (O3' phase). This surface treatment and magnesium As a result of suppressing the phase transition to the H1-3 phase by doping, the cutoff voltage is 4.7V. Crystalline degradation and cracking were suppressed even after the cycling process.

[0395] The ragon plot shown in Figure 53 indicates that the positive electrode active material of one aspect of the present invention is a practical positive electrode material. This indicates that it has the highest energy density among them. Therefore, the correctness of one aspect of the present invention Extremely active materials have a significant impact on the field of high-energy-density batteries and mobile electronics. It is expected to contribute to the progress of [the field].

[0396] Furthermore, this specification and other documents describe the basic mechanism of phase transitions due to cation insertion / extraction. This also provided valuable insights. This discovery can be applied to other cathode materials where phase transitions cause degradation. It's possible. [Examples]

[0397] In this embodiment, a positive electrode active material according to one aspect of the present invention, prepared in the same manner as in Example 1, is used. Half-cells were fabricated under conditions slightly different from those in Example 1, and charge / discharge tests were conducted under conditions slightly different from those in Example 1. I did so. I also analyzed the crystal structure using ex situ XRD.

[0398] Half Cell Active material 96 wt%, conductive additive carbon black (Denka Black®), (Manufactured by Denka Co., Ltd.) 2 wt%, mixed with 2 wt% polyvinylidene fluoride as a binder. An LCO positive electrode was fabricated. At this time, in order to increase the density of the positive electrode active material layer on the positive electrode current collector, The pressing process was performed using a press machine. The conditions for the pressing process were: First press (wire pressure 2 The conditions were set to perform a second press (linear pressure 1467kN / m) after the first press (10kN / m). The upper and lower rolls of the roll press machine were both set to 120°C. The quality of the active material... The dose load was 14.5 mg / cm³. 2 The electrode density was set to approximately 3.9 g / cm³. 3 It was set to a certain extent.

[0399] The electrolyte is ethylene carbonate / diethyl carbonate (EC / DEC = volume ratio 3: 7) Using a solution of 1M LiPF6 dissolved in 2wt% vinylene carbonate (VC) Ta.

[0400] Half-cells were prepared in the same manner as in Example 1, except for the conditions mentioned above.

[0401] ≪Charge / Discharge Test≫ A charge-discharge test was performed using the half-cell prepared as described above. First, a discharge rate test was conducted. Then, the charge-discharge cycle test was performed.

[0402] The conditions for the discharge rate test are described below. In the first charge-discharge cycle, the voltage is reduced to approximately 4.6V. Charging is performed at a constant current of 0.2C, then at a constant voltage until the current value becomes 0.05C, and then, The battery was discharged at a constant current of 0.2C until it reached 3.0V. In the second charge-discharge cycle, it reached approximately 4.6V. Then, it is charged with a constant current of 0.5C, and then charged with a constant voltage until the current value becomes 0.05C. Next, it was discharged at a constant current of 0.1C until it reached 3.0V. In the third charge-discharge cycle, approximately 4.6 Charge at a constant current of 0.5C until the current reaches V, then charge at a constant voltage until the current value becomes 0.05C. Subsequently, it was discharged at a constant current of 1.0C until it reached 3.0V. In the fourth charge-discharge cycle, approximately 4 Constant current charging at 0.5C until the voltage reaches 0.6V, then constant voltage charging until the current value reaches 0.05C. Then, it was discharged at a constant current of 2.0C until it reached 3.0V. Note that here, 1C was used at 200mA. The value was set to / g. The ambient temperature for the measurement environment was 25°C. Furthermore, the period from the completion of charging to the start of discharging was measured. The pause time after charging, and the pause time after discharge completion to the start of charging, are both 10 minutes. That's what I decided.

[0403] The conditions for the charge-discharge cycle test are described below. The battery is charged at a constant current of 0.5C until it reaches approximately 4.6V, and then... Constant voltage charging was performed until the current value reached 0.05C. Discharging was performed at 1C until the voltage reached 3.0V. Constant current discharge was performed. Here, 1C was defined as 200mA / g. The ambient temperature during measurement was... The temperature was set to 45℃. Additionally, the post-charge pause time from the completion of charging to the start of discharging, and the time from the completion of discharging to the start of charging were also considered. The post-discharge rest period before starting to charge was set to 10 minutes for each. Note that charging and discharging are as described above. In addition to the termination conditions based on voltage and current values, a termination condition of 20 hours was set for each. Ta.

[0404] ≪ex situ XRD≫ In the charge-discharge cycle described above, the positive electrode active material according to one aspect of the present invention enters a discharge state. Does it have a lithium cobalt oxide crystal structure, and does it have an O3' phase in the charged state? We conducted a survey to find out if they were doing so.

[0405] To analyze the discharge state, several half-cells that had undergone the above discharge rate test were prepared. Then, after performing one charge-discharge cycle under the above charge-discharge cycle test conditions, the half-cell was disassembled. The conditions for XRD measurement are as follows: After 5 charge-discharge cycles, the half-cell is disassembled and then XRD measurement is performed. The three conditions for disassembling the half-cell after 30 charge-discharge cycles and performing XRD measurements are as follows: XRD measurements were performed after discharge in this case.

[0406] Multiple half-cells that had undergone the above discharge rate test were prepared for post-charge XRD measurement. Then, the same charge-discharge test as described above was performed. Subsequently, the charge-discharge cycle test described above was performed. Under conditions similar to the experiment, after one charge-discharge cycle, the half-cell was recharged and then disassembled. The conditions for XRD measurement are as follows: After 5 charge-discharge cycles, a half-cell that has been charged again is disassembled. The conditions for XRD measurement, and the disassembly of a half-cell that was recharged after 30 charge-discharge cycles. XRD measurements were performed after charging under three conditions for XRD measurement.

[0407] In all cases, the half-cell was dismantled within one hour after the discharge or charge was completed. In dismantling a half-cell in its current state, the positive electrode is removed while still under high voltage charge, Using specialized tools, the dismantling was carried out carefully to avoid short circuits. The dismantling process involved the dew point... And a glove box filled with argon with controlled oxygen concentration was used. The dew point of the lobe box is preferably -70°C or lower, and the oxygen concentration is 5 ppm. The following is preferable. Also, after a long time has passed since the above charging, self-discharge occurs. Because the crystal structure of the positive electrode active material may change, it is necessary to disassemble and analyze it as soon as possible. This is preferable.

[0408] The positive electrode obtained by disassembling the half-cell is sealed inside the glove box. I placed the sample in a sample holder for XRD measurement. Then I set this on the stage of the XRD device. This allows the positive electrode to be kept in an argon atmosphere even during XRD measurements.

[0409] Subsequently, XRD measurements were started within 15 minutes. The XRD equipment and conditions are as follows: ru. XRD system: Bruker AXS D8 ADVANCE X-ray: CuKα1 ray Output: 40kV, 40mA Divergence angle: Div.Slit, 0.5° Detector: LynxEye Scanning method: 2θ / θ continuous scan Measurement range (2θ): 15° to 75° Step width (2θ): 0.01° setting Counting time: 1 second / step Sample stage rotation: 15 rpm

[0410] Figure 54 shows the XRD pattern of the positive electrode after discharge. For comparison, the O3 phase with stoichiometric composition is shown. Lithium cobalt oxide (LiCoO2) and lithium-deficient O3 phase (Li) 0.68 The CoO2 pattern is also shown. The graph shows an enlarged view of the range between 18° and 21° from Figure 54. Figure 55(A) shows a graph of the range between 42° and 48°, and Figure 55(B) shows a magnified view of this range. A positive electrode having a positive electrode active material according to one aspect of the present invention will not undergo 30 cycles at 45°C. The presence of a clear peak suggests that the crystallinity did not decrease after discharge.

[0411] Figure 56 shows the XRD pattern of the positive electrode after charging. For comparison, the O3' phase and H1-3 phase are shown. O3(Li 0.35 The pattern of the CoO2 phase is also shown. Figure 56 shows the range from 18° to 21°. Figure 57(A) shows an enlarged graph of the range below, specifically the range between 42° and 48°. The graph is shown in Figure 57(B). The positive electrode active material of one embodiment of the present invention is in a high-voltage charging state. The pole pattern roughly matches the reference pattern (O3') of the O3' phase. After charging for 1 cycle, after charging for 5 cycles, and after charging for 30 cycles, Even in the case of deviation, it was confirmed that the positive electrode active material of one embodiment of the present invention has an O3' phase. Therefore, a battery having a positive electrode active material according to one aspect of the present invention has a number of charge-discharge cycles. Even when the amount increases, it is possible to maintain the O3' phase, which is a good result. This is considered to be one of the factors that influence the discharge cycle characteristics. [Explanation of Symbols]

[0412] 300 Lithium-ion batteries 301 Positive electrode can 302 Negative electrode can 303 Gasket 304 Positive electrode 305 Positive electrode current collector 306 Positive electrode active material layer 307 Negative electrode 308 Negative electrode current collector 309 Negative electrode active material layer 332 Washer 342 Spacer 500 Lithium-ion batteries 506 negative electrode 507 Positive electrode 508 Adhesive area 509 Exterior 510 Negative lead electrode 511 Positive lead electrode 550 Current collector 553 Carbon Black 554 Graphene 555 carbon fiber 561 Cathode active material 562 Second Active Material 601 Positive Cap 602 Battery Can 603 Positive terminal 604 Positive electrode 605 Electrolyte layer 606 negative electrode 607 Negative terminal 608 Insulating board 609 Insulating board 611 PTC element 613 Safety valve mechanism 614 Conductive plate 615 Energy Storage System 616 Lithium-ion battery 620 Control Circuit 621 Wiring 622 Wiring 623 Wiring 624 Conductors 625 Insulator 626 Wiring 627 Wiring 628 Conductive plate 911a terminal 911b terminal 913 Lithium-ion battery 930 cabinets 930a enclosure 930b enclosure 931 negative electrode 931a Negative electrode active material layer 932 Positive electrode 932a Cathode active material layer 933 Electrolyte layer 950 Wound body 950a Wound body 951 terminal 952 terminals 1300 rectangular lithium-ion battery 1301a First battery 1301b First battery 1302 Battery Controller 1303 Motor Controller 1304 Motor 1305 Gear 1306 DC-DC Circuit 1307 Electric Power Steering 1308 Heater 1309 Defogger 1310 DC-DC Circuit 1311 Second battery 1312 Inverter 1313 Audio 1314 Power windows 1315 Lamps 1316 Tires 1317 Rear Motor 1320 Control circuit section 1321 Control circuit section 1322 Control Circuit 1324 Switch section 1413 Fixed part 1414 Fixed part 1415 Battery Pack 1421 Wiring 1422 Wiring 2001 Automobile 2002 Transport Vehicle 2003 Transport Vehicles 2004 aircraft 2032 CR 2100 Mobile phone 2101 enclosure 2102 Display section 2103 Operation Buttons 2104 External connection port 2105 Speaker 2106 Mike 2107 Lithium-ion battery 2200 Battery Pack 2201 Battery Pack 2202 Battery Pack 2203 Battery Pack 2300 Unmanned Aircraft 2301 Lithium-ion battery 2302 Rotor 2303 Camera 6300 Cleaning Robot 6301 enclosure 6302 Display section 6303 Camera 6304 Brush 6305 Operation Buttons 6306 Lithium-ion battery 6310 Garbage 6400 robots 6401 Illuminance Sensor 6402 Microphone 6403 Top camera 6404 Speaker 6405 Display section 6406 Lower camera 6407 Obstacle Sensor 6408 Moving mechanism 6409 Lithium-ion battery 6800 satellite 6801 aircraft 6802 Solar Panel 6803 Antenna 6805 Lithium-ion battery 6900 probe 6901 aircraft 6902 Solar Sail 6905 Lithium-ion battery 6910 Spaceship 6911 aircraft 6912 Solar Panel 6913 Lithium-ion battery 6920 rover 6921 aircraft 6922 Solar Panel 6923 Lithium-ion battery 8600 Scooter 8601 Side Mirror 8602 Energy Storage Device 8603 Turn signal light 8604 Under-seat storage 8700 Electric Bicycle 8701 Lithium-ion battery 8702 Energy storage device 8703 Display section 8704 Control Circuit

Claims

1. A lithium-ion secondary battery having a positive electrode and a negative electrode, The positive electrode has a positive electrode active material comprising cobalt, oxygen, magnesium, nickel, and aluminum. The positive electrode active material has a region in which, when its cross-section is measured using an electron probe microanalyzer (EPMA) at an accelerating voltage of 10 kV, the atomic ratio of nickel (Ni) to cobalt (Co), Ni / Co, is 0.002 or more and 0.05 or less. Lithium-ion rechargeable battery.

2. The positive electrode active material has a region in which, when its cross-section is measured using an electron probe microanalyzer (EPMA) at an accelerating voltage of 10 kV, the atomic ratio of magnesium (Mg) to cobalt (Co), Mg / Co, is 0.005 or more and 0.015 or less. The lithium-ion secondary battery according to claim 1.

3. The positive electrode active material, when its cross-section is measured using an electron probe microanalyzer (EPMA) at an acceleration voltage of 10 kV, has a region where the atomic ratio of aluminum (Al) to cobalt (Co), Al / Co, is 0.005 or less or undetectable. The lithium-ion secondary battery according to claim 1.

4. The positive electrode active material has a nickel (Ni) to cobalt (Co) atomic ratio (Ni / Co) measured by X-ray photoelectron spectroscopy (XPS) that is greater than the nickel (Ni) to cobalt (Co) atomic ratio (Ni / Co) measured by measuring its cross-section using an electron probe microanalyzer (EPMA) at an accelerating voltage of 10 kV. The lithium-ion secondary battery according to claim 1.

5. The aforementioned positive electrode active material has a magnesium (Mg) to cobalt (Co) atomic ratio (Mg / Co) measured by X-ray photoelectron spectroscopy (XPS) that is greater than the magnesium (Mg) to cobalt (Co) atomic ratio (Mg / Co) measured by measuring its cross-section using an electron probe microanalyzer (EPMA) at an accelerating voltage of 10 kV. The lithium-ion secondary battery according to claim 2.

6. The positive electrode active material has an atomic ratio of aluminum (Al) to cobalt (Co), Al / Co, measured by X-ray photoelectron spectroscopy (XPS), which is greater than the atomic ratio of aluminum (Al) to cobalt (Co) measured by measuring its cross-section using an electron probe microanalyzer (EPMA) at an accelerating voltage of 10 kV. The lithium-ion secondary battery according to claim 3.

7. The positive electrode active material has a layered rock salt type crystalline structure that belongs to space group R-3m in the discharge state. The aforementioned crystal structure has a lattice constant of the c axis that is greater than 14.055 Å and less than 14.060 Å. A lithium-ion secondary battery according to any one of claims 1 to 6.

8. The positive electrode active material has a binding energy that shows maximum intensity in the narrow scan spectrum of Mg1s obtained by X-ray photoelectron spectroscopy (XPS) that is greater than 1303.3 eV and less than 1306.3 eV. A lithium-ion secondary battery according to any one of claims 1 to 6.

9. The positive electrode active material has a region having a rock salt-type crystalline structure and a region having a layered rock salt-type crystalline structure. The region having the rock salt type crystal structure and the region having the layered rock salt type crystal structure are coherently bonded. A lithium-ion secondary battery according to any one of claims 1 to 6.

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