Lithium-ion rechargeable battery

Abstract

To prevent cobalt segregation from occurring on the negative electrode and separator, the surface of the positive electrode active material particles To prevent cobalt (Co) and oxygen (O) from being released from the surface, and to prevent the positive electrode active material particles from Reduces the occurrence of racks and defects. [Solution] Lithium, metal element M1, one or both of the divalent and ivvalent metal elements M 2, and also containing oxygen, the metal atom M1 is one or more of cobalt, manganese, and nickel. Yes, the active material particles have one or more crystallites, and the active material particles have a first located inside It has a region and a second region located outside the first region, and the second region is the same as the first region Active material particles containing a higher amount of the metallic element M2 are used in secondary batteries.

Description

[Technical Field]

[0001] One aspect of the present invention relates to a product, a method, or a method of manufacture. Alternatively, the present invention relates to a process. This relates to machines, manufacturers, or compositions of matter. One aspect of the present invention relates to semiconductor devices, display devices, light-emitting devices, energy storage devices, lighting devices, or electronic devices. This relates to a method for manufacturing a device. In particular, to a positive electrode active material that can be used in a secondary battery, a secondary battery, and This relates to electronic devices that have a secondary battery.

[0002] In this specification, the term "energy storage device" refers to all elements and devices that have an energy storage function. For example, lithium-ion secondary batteries and other rechargeable batteries (also called secondary batteries) This includes muon capacitors and electric double-layer capacitors.

[0003] 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]

[0004] There is a great deal of development going on in electronic devices that users carry with them and electronic devices that users wear on their devices.

[0005] Electronic devices carried by users or worn by users are examples of primary energy storage devices. It operates using batteries or rechargeable batteries as a power source. Electronic devices carried by the user are intended for long-term use. It is desirable to do so, and for that purpose, a large-capacity secondary battery should be used. When a battery is built in, high-capacity rechargeable batteries become large and heavy, which is a problem. Development is underway to create small, thin, and high-capacity rechargeable batteries that can be built into electronic devices.

[0006] In particular, since a high voltage of 4V class can be obtained, lithium cobalt as a positive electrode active material for secondary batteries composite oxide (LiCoO₂) is widely used. Further, Patent Document 1 discloses a positive electrode active material plate-like particles.

[0007] Lithium-ion secondary batteries with high output and high capacity are used in mobile phones, smartphones, or portable information terminals such as notebook computers, portable music players, digital cameras, medical devices , or hybrid vehicles (HEV), electric vehicles (EV), or plug-in hybrid vehicles (PHEV) and other next-generation clean energy vehicles. Along with the development of the semiconductor industry, the demand for these batteries has expanded rapidly, and they have become indispensable to the modern information-oriented society as a rechargeable energy supply source.

[0008] In lithium-ion secondary batteries, repeated charging and discharging cycles cause deterioration of the battery, which has the disadvantage that the discharge capacity becomes smaller compared to the initial discharge capacity. In addition, for lithium ion secondary batteries, there are risks of ignition during use of the device incorporating the lithium-ion secondary battery or due to rapid charging, so safety is also a problematic issue. If many ignition-related problems occur, it will affect not only the secondary battery itself, but also the device equipped with the secondary battery will need to be recalled, leading to huge recall costs, damage to brand reputation, and other significant damage to device manufacturers.

Prior Art Literature

Patent Literature

[0009]

Patent Document 1

[0010] Lithium-ion secondary batteries and the positive electrode active materials used therein have cycle characteristics, capacity, Furthermore, there is still room for improvement in various aspects such as charge / discharge characteristics, reliability, safety, and cost. It remains.

[0011] To identify the cause of degradation in lithium-ion secondary batteries, the positive electrode active material is composed of particles (lithium ion). Upon observation of the Baltic complex oxide (LiCoO2), multiple cracks were found in the particles. Cracks (including fissures) were observed within the particles. Additionally, cracks observable in SEM images were found within the particles. It is believed that there are many other defects as well.

[0012] The inventors have discovered that cobalt (Co) and acid are extracted from the surface of particles, mainly from multiple cracks and defects in the particles. Element (O) or cobalt oxide (Co+O) is released or dissolved into the electrolyte. It is suspected that this is one of the causes of degradation in lithium-ion secondary batteries.

[0013] Furthermore, cobalt released into the electrolyte or dissolved into it segregates onto the negative electrode, forming segregated deposits. It has also been observed that cobalt segregates inside the separator. It is being observed.

[0014] Given these circumstances, in order to prevent cobalt segregation from occurring on the negative electrode and separator, the positive electrode To prevent cobalt (Co) and oxygen (O) from being released from the surface of the active material particles, positive electrode It is crucial to reduce the occurrence of cracks and defects in the active material particles.

[0015] One aspect of the present invention, when used in a lithium-ion secondary battery, provides a solution that is inferior in charge-discharge cycles. One of the objectives is to provide an active material that does not undergo transformation. Alternatively, one aspect of the present invention is to provide a high-capacity active material. One objective of this invention is to provide a secondary battery. Alternatively, one aspect of this invention provides a battery with excellent charge and discharge characteristics. One objective is to provide a secondary battery that is safe or One of our objectives is to provide highly reliable rechargeable batteries.

[0016] Alternatively, one aspect of the present invention provides novel materials, active materials, energy storage devices, or methods for producing them. One of the objectives is to provide it.

[0017] Furthermore, the description of these problems does not preclude the existence of other problems. The embodiments do not need to solve all of these problems. It is possible to extract other issues from the description of the requested terms. [Means for solving the problem]

[0018] To achieve the above objectives, one aspect of the present invention comprises a current collector and an active material layer on the current collector. The active material layer has multiple active material particles in contact with the current collector, and the active material particles are lithium, metal elements It contains element M1, one or both of the divalent and IV valent metallic elements M2, and oxygen, and a metallic element The particle M1 is one or more of cobalt, manganese, and nickel, and the active material particle is one or Having multiple crystallites, the active material particle has a first region located inside and outside the first region It has a second region located therein, and the second region contains more of the metallic element M2 than the first region. It is a positive electrode characterized by [this feature].

[0019] In the above configuration, the metal element M2 is magnesium, calcium, silicon, and titanium. It is one or more of the following. Alternatively, the metallic element M2 is magnesium, calcium, and titanium. The active material particles have a surface near the location of II-valent and IV-valent metal oxides, specifically magnesium oxide. MgO X ), calcium oxide (CaO X ), silicon oxide (SiO X ) and others segregate This prevents the release of cobalt or oxygen from the particle surface. In this specification, segregation This refers to a solid composed of multiple elements (for example, A, B, C), where one element (for example, B) This refers to the phenomenon of non-uniform distribution of cobalt or oxygen in the electrolyte. This makes it possible to provide an active material that does not degrade during charge-discharge cycles.

[0020] In the above configuration, the second region may further contain fluorine. Also, positive electrode active material The presence of fluorine in the particle quality improves corrosion resistance to hydrofluoric acid produced when the electrolyte decomposes. It may happen.

[0021] In the above configuration, X-ray diffraction (XRD) analysis is performed The crystallite size measured is 0.5 μm or larger, preferably 1 μm or larger.

[0022] In the above configuration, the size of the active material particles to be measured is between 1 μm and 50 μm. Oh, the particle size refers to D50 (also called the median diameter).

[0023] Another invention relates to a secondary battery having a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode has a current collector and an active material layer on the current collector, and the active material layer is in contact with the current collector. It has multiple active material particles, and the active material particles are lithium, a metallic element M1, and one of the I-valent and IV-valent elements. It contains one or both of the metal elements M2, as well as oxygen, and the metal atom M1 is cobalt, manganese , and one or more nickel, and the active material particles have one or more crystallites, and the active material particles The child has a first region located inside and a second region located outside the first region. The second region contains more of the metallic element M2 than the first region, and the secondary battery has a lifespan of 100 cycles. The capacity after repeated charging and discharging is 78% or more of the initial capacity.

[0024] Another invention relates to a secondary battery having a positive electrode, a negative electrode, an electrolyte, and a separator. The positive electrode has a current collector and an active material layer on the current collector, and the active material layer is in contact with the current collector. It has multiple active material particles, and the active material particles are lithium, a metallic element M1, and one of the I-valent and IV-valent elements. It contains one or both of the metal elements M2, as well as oxygen, and the metal atom M1 is cobalt, manganese , and one or more nickel, and the active material particles have one or more crystallites, and the active material particles The child has a first region located inside and a second region located outside the first region. The second region contains more of the metallic element M2 than the first region, and the secondary battery lasts for 10 cycles or more. The capacity after repeated charging and discharging within a range of 30 cycles or less is 98% or more of the initial capacity. be.

[0025] Furthermore, another invention relating to the manufacturing method involves using the sol-gel method to process the divalent and IV-valent... By coating the first active material particle having defects with either one or both of the metal elements M2, The first step is to form two active material particles, and the second active material particles are heat-treated to form a third active material A second step to obtain quality particles, and a third step to coat the slurry containing the third active material particles onto the current collector. The process comprises the steps of, and defects contained in the first active material particles are repaired in the second step. This is a method for producing a positive electrode characterized by the following:

[0026] In the above manufacturing method, the size of the crystallites contained in the third active material particle is equal to that of the first active material particle. It is larger than the crystallite contained in the child.

[0027] In the above manufacturing method, the size of the crystallites contained in the third active material particle is equal to that of the first active material particle. This is more than twice the number of crystallites contained in the child.

[0028] In the above preparation method, the crystallite size is measured by XRD analysis.

[0029] In the above manufacturing method, the second step is to use an oxygen-containing atmosphere at a temperature of 600°C to 1000°C. This process is performed by heating at temperatures between 600°C and 1000°C to reduce particle cracks and defects. This makes the surface of the particles shiny and reduces the surface area. Reducing the surface area allows for energy By achieving a stable state, a safe and reliable secondary battery can be realized.

[0030] In the above manufacturing method, the first active material particles contain lithium, a metallic element M1, and oxygen. The metal atom M1 is one or more of cobalt, manganese, and nickel.

[0031] In this specification, etc., the layered rock salt type knots of a composite oxide containing lithium and the metal element M1 Crystal structure refers to a rock salt-type ionic arrangement in which cations and anions are arranged alternately, and metallic elements Because M1 and lithium are arranged in a regular pattern to form a two-dimensional plane, two-dimensional diffusion of lithium is possible. This refers to a crystal structure that is functional. It may contain defects such as vacancies in cations or anions. Furthermore, strictly speaking, the layered rock salt crystal structure is a structure in which the lattice of the rock salt crystal is distorted. There are cases where this occurs.

[0032] Furthermore, in this specification, a rock salt-type crystal structure is defined as a structure in which cations and anions are arranged alternately. This refers to a structure that contains certain elements. It is also acceptable for there to be deficiencies in cations or anions. [Effects of the Invention]

[0033] By reducing the size of cracks in the active material particles and decreasing the number of cracks and defects, cobalt and By creating a structure that prevents oxygen from dissolving into the electrolyte, the stability of the crystal structure within the active material particles is further enhanced. This can be improved, resulting in better charge-discharge cycle characteristics.

[0034] Furthermore, it is possible to provide safe and reliable secondary batteries. In addition, novel materials and active We can provide materials, energy storage devices, or methods for manufacturing them.

[0035] Furthermore, the description of these effects does not preclude the existence of other effects. The embodiment does not necessarily have to have all of these effects. Furthermore, other effects are... This will become clear from the description in the specification, drawings, claims, etc., and the specification, drawings Furthermore, it is possible to extract other effects from the descriptions in the claims and other documents. [Brief explanation of the drawing]

[0036] [Figure 1] These are perspective views and cross-sectional views of particles illustrating one aspect of the present invention. [Figure 2] This is a conceptual diagram showing the changes in crystallites and cracks before and after processing, according to one aspect of the present invention. [Figure 3] This is an SEM image showing one aspect of the present invention. [Figure 4]This figure shows a material representing one aspect of the present invention. [Figure 5] This figure shows a step illustrating one aspect of the present invention. [Figure 6] This figure shows a process flow illustrating one aspect of the present invention. [Figure 7] A diagram illustrating a coin-type rechargeable battery. [Figure 8] A diagram illustrating how to charge a rechargeable battery. [Figure 9] A diagram illustrating how to charge a rechargeable battery. [Figure 10] A diagram illustrating the discharge method of a secondary battery. [Figure 11] Cross-sectional view of the active material layer when a graphene compound is used as a conductive additive. [Figure 12] A diagram illustrating a cylindrical rechargeable battery. [Figure 13] A diagram illustrating a rechargeable battery. [Figure 14] A diagram illustrating a rechargeable battery. [Figure 15] A diagram illustrating a rechargeable battery. [Figure 16] A diagram illustrating a rechargeable battery. [Figure 17] A diagram illustrating an example of an electronic device. [Figure 18] A diagram illustrating an example of an electronic device. [Figure 19] A diagram illustrating an example of an electronic device. [Figure 20] A diagram illustrating the crystal structure of lithium cobalt oxide. [Figure 21] A graph showing the cycle characteristics of a secondary battery using the positive electrode active material of Example 1. [Figure 22] A graph showing the rate characteristics of a secondary battery using the positive electrode active material of Example 1. [Figure 23] A graph showing the cycle characteristics of a secondary battery using the positive electrode active material of Example 1. [Modes for carrying out the invention]

[0037] The embodiments of the present invention will be described in detail below with reference to the drawings. However, the present invention is... Not limited to the following description, the form and details can be modified in various ways, as any person skilled in the art would know. This is easily understood. Furthermore, the present invention shall be interpreted as being limited to the contents of the embodiments described below. It's not something that can be done.

[0038] (Embodiment 1) Figure 1(A1) shows an example of a perspective view of an active material particle 110 having multiple cracks 105. Figure 1(A2) shows a cross-sectional view obtained when the cross-section is cut along the dotted line 160 in Figure 1(A1). The active material particles 110 are composite oxide particles containing lithium, metal element M1, and oxygen. It is a child. As the metallic element M1, one or more of cobalt, manganese, and nickel are applied. It is possible.

[0039] In particle 110, multiple crystallites can be observed in a single particle, and as shown in Figure 1(A2), in cross-section... It also has crack 105. Note that the SEM image corresponding to Figure 1(A1) is shown in Figure 3. (A) is shown. The active material particles 110 shown in Figure 1(A1) are untreated and are as they are. When a secondary battery was fabricated using the electrode active material layer and its cycle characteristics were measured, degradation progressed, and the metal element Element M1, such as cobalt, is deposited in the negative electrode or separator.

[0040] The surface of the active material particles 110 shown in Figure 1(A1), particularly the cobalt or oxygen from cracks To prevent leaching, the material is coated with a material containing the metal element M2 and then heated in an oxygen-containing atmosphere at a high temperature. Heat treatment is performed at a temperature of 600°C to 1000°C. Regarding the heat treatment, annealing and Yes, you can. For the metallic element M2, you can use either a metal with a divalent or IV valency, or both. Specifically, one or more of magnesium, calcium, silicon, and titanium are applied. It is possible to coat it using a solge with an alkoxide of the metal element M2. The law can be applied.

[0041] When using Ti as the metal element M2, a sol-gel method using Ti alkoxide was performed. Next, the material is heat-treated in an oxygen-containing atmosphere at a high temperature (between 600°C and 1000°C). By performing a heat treatment along with the sol-gel method using Ti alkoxide, both I-valent and IV-valent ions can be obtained. This causes one or both of the metal elements M2 to move near the surface, preventing the leaching of cobalt or oxygen. The structure is formed by further heat treatment after the sol-gel method using Ti, which results in active material particles. This allows the surface of the child to be smoothed, reducing its surface area and creating a stable state.

[0042] In the sol-gel method, alkoxides of the metal element M2, etc., are formed in cracks of the active material particle 110. It penetrates and repairs the cracks through heat treatment. If the heat treatment temperature is too low, the cracks will not be repaired. It is difficult to achieve this, and if the heating temperature is too high, many oxygen vacancies are formed, affecting its function as a positive electrode active material. This can result in damage to the battery. Furthermore, if the heating temperature is too high, there is a concern about lithium evaporation.

[0043] Particles of a composite oxide containing lithium, the metallic element M1, and oxygen, such as lithium cobalt. Composite oxides (LiCoO2) have oxygen vacancies in their particles, which particularly promotes mass transfer. It is prone to cracking. Therefore, titanium dioxide coated by the sol-gel method is more likely to repair cracks. Titanium compounds obtained by reacting titanium dioxide and LiCoO2 are conductive, and lithium It is suitable because it does not hinder the diffusion of the substance. Similarly, metal alkoxides that become non-stoichiometric oxides and When coated with an aqueous solution of a metal salt of an organic acid, it exhibits electrical conductivity and lithium ion conductivity. Therefore, it is preferable.

[0044] Even small cracks at the edges of particles can cause large cracks due to stress concentration. Therefore, the sol-gel method and heat treatment, which also repair small cracks, are important.

[0045] A perspective view of the treated active material particles 100 is shown in Figure 1(B1). Furthermore, the treated active material particles Figure 1(B2) shows a cross-sectional view when the cross-section is cut along the dotted line 150.

[0046] As shown in Figure 1(B2), after treatment, the cracks disappear, crystallites partially grow, and active material The number of crystallites within the particle decreases.

[0047] Figure 2 shows an example of a model diagram illustrating the changes in crystallites within active material particles before and after treatment. Here are four examples.

[0048] Several patterns are possible for the changes in crystallites due to the treatment. Figure 2 shows the changes in crystallites. Let's explain an example of change.

[0049] First, Figure 2(A1) shows that in particle 110, a crack 105 occurs between different crystallites. This is an example. Figure 2(A2) shows the particle 110 from Figure 2(A1) after the above treatment has been performed. Child 100. By performing the process, crack 105 is repaired and different crystallites are one It is possible that it will become a crystallite.

[0050] Next, Figure 2(B1) shows that in particle 110, there are numerous small cracks 105 in one crystallite. This is an example of what is happening. Figure 2(B2) shows the particle 110 in Figure 2(B1) after the above treatment has been applied. These are the particles 100 after the process. By performing the treatment, numerous cracks 105 are repaired, and defects It is possible that no crystallites will be formed.

[0051] Next, referring to FIG. 2(C1), in particle 110, a crack 105 is generated in one crystallite which is an example. FIG. 2(C2) shows particle 1 after the above-described treatment is performed on the particle 110 of FIG. 2(C1) 00. It is conceivable that through the treatment, the crack 105 is repaired and a defect-free crystallite is obtained in this case.

[0052] Next, referring to FIG. 2(D1), this is an example where crystal axes of adjacent crystallites are different in particle 110 FIG. 2(D2) shows particle 100 after the above-described treatment is performed on the particle 110 of FIG. 2(D1) It is conceivable that through the treatment, adjacent crystallites are combined into one crystallite. However for adjacent crystallites, it is preferable that the cubic close-packed structure of oxygen is consistent .

[0053] Furthermore, through the heat treatment, magnesium oxide (MgO X (0<X)), calcium oxide (CaO X (0<X)), silicon oxide (SiO X (0<X)) and the like are segregate ed on the outer second region. With such a structure, cracks are less likely to occur, and cobalt in the active material particles or oxygen does not flow out into the electrolytic solution.

[0054] Note that SEM photographs of a plurality of active material particles after the treatment are shown in FIG. 3(B).

[0055] The active material particles 100 after the treatment have a reduced number of cracks and defects, and have a structure in which cobalt and oxygen do not elute into the electrolytic solution, which improves the stability of the crystal structure in the active material particles. Therefore, the charge-discha rge cycle characteristics are further improved. Furthermore, the active material particle 100 after the treatment is a novel material, and can also be referred to as a novel positive electrode active material.

[0056] By using the processed active material particles 100 in the positive electrode active material layer, a safe and reliable secondary electrode is created. We can provide batteries.

[0057] (Embodiment 2) A method for coating the active material particles 110 having cracks as shown in Embodiment 1 is a sol. Liquid-phase methods including gel methods, solid-phase methods, sputtering methods, vapor deposition methods, and CVD (chemical vapor deposition) Methods such as the long-range laser method and the PLD (pulsed laser deposition) method can be applied.

[0058] In this embodiment, a sol-gel method is applied, which is expected to provide uniform coating and can be processed at atmospheric pressure. This will be done. The manufacturing method will be explained using Figures 4, 5, and 6.

[0059] <Sol-gel method> First, dissolve the alkoxide of metal element M2 in alcohol. The metals used include one or both of the above-mentioned divalent and ivvalent metals, specifically magnesium. Nesium, calcium, silicon, and titanium can be used. Furthermore, as M2 alkali metal elements, alkaline earth metal elements, alkali metal elements and alkaline earth metal elements Various elements other than prime elements, such as typical metal elements and transition metal elements, may also be used.

[0060] Alkali metal elements include Li, Na, K, Rb, Cs, and Fr, and alkaline earth Examples of similar metallic elements include Be, Mg, Ca, Sr, Ba, and Ra, and alkali metal elements. Other typical metallic elements besides chromium and alkaline earth metal elements include Sc, Ti, V, Cr, M n, Fe, Co, Ni, Cu, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Examples include Hf, Ta, W, Re, Os, Ir, Pt, Au, and as for transition metal elements, A Examples include l, Zn, Ga, Ge, Cd, In, Sn, Sb, Hg, Ti, Pb, Bi, and Po. It is possible.

[0061] Figure 4(A-1) shows the general formula for the alkoxide of the metal element M2. M2 represents an IV-valent metallic element, and R can be the same or different. These can be any alkyl group having 1 to 18 carbon atoms, or a substituted or unsubstituted alkyl group having 6 carbon atoms. It represents an aryl group of up to 13 carbon atoms. The alkyl group having 1 to 18 carbon atoms is a methyl group, etc. Tyl group, propyl group, hexyl group, octyl group, decyl group, dodecyl group, octadecyl group Linear alkyl groups such as isopropyl groups, isobutyl groups, t-butyl groups, and other branched alkyl groups. Examples of such groups include the aryl group having 6 to 13 carbon atoms, the phenyl group, the naphthyl group, Biphenyl groups and fluorenyl groups are examples of specific examples. Note that R is as described above. Not limited to this.

[0062] Figure 4(A-2) shows a titanium alkoxide in which titanium is used for M2 in Figure 4(A-1). The general formula is shown. Specific examples of titanium alkoxides include tetramethoxytitanium and tetraethoxy Titanium, tetra-n-propoxytitanium, tetra-i-propoxytitanium (in Figure 4 (A- 3))(Tetraisopropyl orthotitanate, Titanium isopropoxide, Titanium m tetraisopropoxide (sometimes written as TTIP, etc.), tetra -n-butoxytitanium, tetra-i-butoxytitanium, tetra-sec-butoxytitanium Examples include tetra-t-butoxytitanium.

[0063] Alcohols are preferred as solvents for dissolving the alkoxide of metal element M2, and primary alcohols Alcohols or secondary alcohols are particularly preferred due to their high solubility of the above-mentioned metal alkoxides. For example methanol, ethanol, propanol, 2-propanol, butanol, 2-branol Tanol, etc., can be used.

[0064] Next, a compound solution containing lithium and metal element M1 is added to an alcoholic solution of the alkoxide of metal element M2. Add the oxide particles (active material particles 110 shown in Embodiment 1) and stir. Then add water. By adding (H2O), the hydrolysis reaction between water and titanium alkoxide occurs as shown in Figure 4(B). This is produced. At the same time, an acid or base may be added as a catalyst. Also, the metal element M2 is A similar water-based solution of cooxide can be obtained by placing it in a water-containing atmosphere and stirring. A decomposition reaction occurs.

[0065] Furthermore, following the hydrolysis reaction in Figure 4(B), the dehydration condensation reaction in Figure 4(C) occurs. The hydrolysis shown in B) and the condensation reaction shown in Figure 4(C) occur repeatedly, resulting in the formation of the metal element M2 A sol of oxide is formed, and by allowing the reaction to proceed further, an oxide of the metal element M2 is produced. It forms a gel.

[0066] Here, the particle surface of the composite oxide containing lithium and metal element M1 has hydroxyl groups (OH groups) It is known to exist. As shown in Figures 4(D-1) and 4(D-2), lithium The hydroxyl groups on the particle surface of the composite oxide containing metal element M1 are shown in Figure 4(B) as metal element M The hydroxyl group of the metal (M2) produced by hydrolysis from the alkoxide of 2, and Figure 4(C) By undergoing the dehydration condensation reaction shown, a different gold from M1 is produced on particles containing a metal (M1) oxide. A sol or gel containing an oxide of (M2) is formed.

[0067] Thereafter, particles 111 are collected by filtration, and the solvent is removed, whereby the material containing the metal element M2 can be coated onto composite oxide particles having lithium and the metal element M1.

[0068] Next, a method for obtaining active material particles 100 by coating particles 111 with a titanium oxide using a sol-gel method will be specifically described with reference to FIGS. 5 and 6.

[0069] <Mixing of metal alkoxide solution and particles 111 (S14 in FIG. 6)> First, TTIP 171 is dissolved in isopropanol 170, and particles 111 are mixed thereinto (see FIG. 5(A)).

[0070] <Coating of titanium oxide on particles 111 by sol-gel method (S15 in FIG. 6)> The solution shown in FIG. 5(A) is stirred for 4 hours under conditions of 25°C and 90% RH humidity. In this treatment, using hydrolysis and dehydration polycondensation reactions that occur between water in the atmosphere and TTIP on the surface of particles 111, particles 111 are coated with TiO 2 sol 172 (see FIG. 5(B)). The reaction is further allowed to proceed to generate TiO x 2 gel on the particle surfaces. x

[0071] <Collection of TiO x 2 gel-coated particles 111 (S16 in FIG. 6)> In FIG. 6, the mixed liquid after completion of the treatment of S15 is filtered, and the residue is collected.

[0072] <Drying of TiOx gel (S17 in FIG. 6)> In FIG. 6, the residue collected in the treatment of S16 is vacuum-dried at 70°C for 1 hour to obtain a powder. Here ​​​​​​Here, particles 111 are coated on the surface thereof with a dried gel 173 containing Ti oxide (see FIG. 5(C) ).

[0073] <Drying of TiOx gel (S18 in FIG. 6)> In FIG. 6, the powder obtained by the treatment of S17 is heated at 800°C (temperature increase rate: 200°C / hour) with a holding time of 2 hours and under the condition that the flow rate of the oxygen-containing atmosphere is 10 L / min, thereby obtaining active material particles 100 ( see FIG. 5(D)).

[0074] In the present embodiment, an example in which titanium alkoxide is used as the alkoxide of the metal element M2 is shown above, but the present invention is not particularly limited thereto, and other metal alkoxides may be used. Further, the heating conditions are also not particularly limited, and a plurality of temperature increase conditions and heat treatment steps may be performed. Further, the slow cooling conditions after heating are also not particularly limited, and the temperature decrease conditions may be adjusted as appropriate.

[0075] Note that the present embodiment can be freely combined with other embodiments.

[0076] (Embodiment 3) In the present embodiment, an example of the shape of a secondary battery including active material particles 100 that functions as the positive electrode active material described in the previous embodiments will be described. The description of the previous embodiments can be referred to for the materials used in the secondary battery described in the present embodiment.

[0077] [Coin-type Secondary Battery] First, an example of a coin-type secondary battery will be described. FIG. 7(A) is a coin-type (single-layer flat type) secondary battery external view, and FIG. 7(B) is a cross-sectional view thereof.

[0078] The coin-type secondary battery 300 includes a positive electrode can 301 also serving as a positive electrode terminal and a negative electrode can also serving as a negative electrode terminal 302 is insulated and sealed by a gasket 303 made of polypropylene or the like. The positive electrode 304 consists of a positive electrode current collector 305 and a positive electrode active material layer 306 provided in contact with it. It is formed by the following. The negative electrode 307 is provided in contact with the negative electrode current collector 308. It is formed by a negative electrode active material layer 309.

[0079] Furthermore, the positive electrode 304 and negative electrode 307 used in the coin-type secondary battery 300 are each made of live metal The layers only need to be formed on one side.

[0080] The positive electrode container 301 and the negative electrode container 302 are made of nickel and aluminum, which are corrosion-resistant to the electrolyte. , metals such as titanium, or alloys thereof, or alloys of these with other metals (e.g., stainless steel) (etc.) can be used. In addition, nickel and aluminum can be used to prevent corrosion by the electrolyte. It is preferable to cover it with a material such as a nut. The positive electrode can 301 is connected to the positive electrode 304, and the negative electrode can 302 is connected to the negative electrode 30 Connect each of the 7s electrically.

[0081] These negative electrode 307, positive electrode 304, and separator 310 are impregnated with the electrolyte, as shown in Figure 7(B). As shown, with the positive electrode can 301 at the bottom, the positive electrode 304, separator 310, negative electrode 307, and negative The electrode cans 302 are stacked in this order, and the positive electrode can 301 and the negative electrode can 302 are connected via a gasket 303. The coin-shaped rechargeable battery 300 is manufactured by crimping the parts together.

[0082] The positive electrode 304 is provided with active material particles 100 that function as the positive electrode active material described in the previous embodiment. By using this, a coin-type secondary battery 300 with excellent cycle characteristics can be created.

[0083] Here, we will use Figure 7(C) to explain the current flow during the charging of a secondary battery. When a secondary battery is considered as a closed circuit, the movement of lithium ions and the flow of current are in the same direction. Yes. In lithium-ion secondary batteries, the anode and cathode are used during charging and discharging. The cathode is swapped, and the oxidation and reduction reactions are reversed, so the reaction potential changes. The electrode with the higher potential is called the positive electrode, and the electrode with the lower reaction potential is called the negative electrode. Therefore, in this specification Therefore, whether charging or discharging, or even when applying a reverse pulse current, Even when an electric current is flowing, the positive electrode is called the "positive electrode" or "+ electrode (plus electrode)," and the negative electrode is called the "negative electrode." We will refer to this as the "negative electrode" or "- electrode (minus electrode)." In relation to oxidation and reduction reactions... If we use the terms anode and cathode, then during charging and discharging, This could be reversed and cause confusion. Therefore, the anode and cathode The term (cathode) will not be used in this specification. When using the terms cathode, specify whether it is during charging or discharging, and indicate the positive electrode ( We will also indicate whether it corresponds to the negative (last) or last (minus) pole.

[0084] The charger is connected to the two terminals shown in Figure 7(C), and the secondary battery 300 is charged. As the battery 300 charges, the potential difference between the electrodes increases. In Figure 7(F), secondary battery 3 From the external terminal of 00, the current flows towards the positive electrode 304, and within the secondary battery 300, the positive electrode 30 Current flows from 4 towards the negative electrode current collector 308, and from the negative electrode towards the external terminals of the secondary battery 300. The direction of the current is defined as the positive direction. In other words, the direction in which the charging current flows is defined as the direction of the current. ru.

[0085] [Charge / discharge method] The charging and discharging of a secondary battery can be performed, for example, as follows.

[0086] ≪CC charging≫ First, let's explain CC charging as one of the charging methods. CC charging is used throughout the entire charging period. This charging method involves supplying a constant current to the secondary battery and stopping the charging process when a predetermined voltage is reached. The secondary battery is assumed to be an equivalent circuit of internal resistance R and secondary battery capacity C, as shown in Figure 8(A). In this case, the secondary battery voltage V B This is the voltage V across the internal resistance R. R and secondary battery capacity C The voltage V C It is the sum of.

[0087] While CC charging is in progress, the switch turns on as shown in Figure 8(A), and a certain amount of power is supplied. Current I flows through the secondary battery. During this time, since the current I is constant, V R Ohm's law = R × I According to the law, the voltage V across the internal resistance R is R It is also constant. On the other hand, the electricity applied to the secondary battery capacity C Pressure V C The voltage increases over time. Therefore, the secondary battery voltage V B The passage of time and They both rise.

[0088] And the secondary battery voltage V B Charging stops when the voltage reaches a predetermined level, for example, 4.3V. When CC charging is stopped, the switch turns off as shown in Figure 8(B), and the current I=0 Therefore, the voltage V across the internal resistance R is... R The voltage becomes 0V. Therefore, the internal resistance R The voltage drop is eliminated, and the secondary battery voltage V B It will decline.

[0089] The secondary battery voltage V during CC charging and after CC charging has stopped. Band charging current An example is shown in Figure 8(C). The secondary battery voltage V was rising while CC charging was being performed. B However, C The image shows a slight decrease after C charging is stopped.

[0090] ≪CCCV charging≫ Next, we will explain CCCV charging, which is a different charging method from the one described above. CCCV charging is First, the battery is charged to a predetermined voltage using CC charging, and then the current that flows through it is charged using CV (constant voltage) charging. This charging method continues until the current level drops to a minimum, specifically until it reaches the cutoff current value.

[0091] While CC charging is in progress, the constant current power supply switch is turned on, as shown in Figure 9(A). The voltage power supply switch is turned off, and a constant current I flows to the secondary battery. During this time, the current I Since it is constant, V R According to Ohm's law, =R × I, the voltage across the internal resistance R is V. R one It is constant. On the other hand, the voltage V across the secondary battery capacity C C It increases over time. Therefore, the secondary battery voltage V B It increases over time.

[0092] And the secondary battery voltage V B When the voltage reaches a predetermined level, for example 4.3V, CC charging is switched to C Switch to V charging. While CV charging is being performed, a constant voltage power supply is used as shown in Figure 9(B). The switch for the constant current power supply is turned on, and the secondary battery voltage V B It becomes constant On the other hand, the voltage V across the secondary battery capacity C... C It increases over time. B =V R +V C Therefore, the voltage V across the internal resistance R RIt decreases over time. Voltage V across resistor R R As V decreases, R According to Ohm's law, =R × I, two The current I flowing through the next battery will also decrease.

[0093] And when the current I flowing through the secondary battery becomes a predetermined current, for example, a current equivalent to 0.01C... , stop charging. When CCCV charging is stopped, all switches will turn off as shown in Figure 9(C). The switch turns off, and the current I becomes 0. Therefore, the voltage V across the internal resistance R is lost. R The voltage becomes 0V. However, the voltage V across the internal resistance R due to CV charging R Because it has become small enough Even if the voltage drop across the internal resistance R disappears, the secondary battery voltage V B It hardly descends at all.

[0094] The secondary battery voltage V during CCCV charging and after CCCV charging has stopped. B and An example of electric current is shown in Figure 9(D). Even when CCCV charging is stopped, the secondary battery voltage V B Mostly It appears that it is not descending at all.

[0095] ≪CC discharge≫ Next, we will explain CC discharge, one of the discharge methods. CC discharge is used throughout the entire discharge period. A constant current is drawn from the secondary battery, and the secondary battery voltage V B When it reaches a predetermined voltage, for example 2.5V This is a discharge method that stops the discharge when it reaches a certain point.

[0096] The secondary battery voltage V during CC discharge B Figure 10 shows an example of the discharge current. According to this, secondary battery voltage V B The image shows it descending.

[0097] Next, we will explain the discharge rate and charge rate. The discharge rate is the ratio of the battery capacity to the charge rate. This is the relative ratio of the current during discharge, and is expressed in units of cubic centimeters (C). Therefore, the current equivalent to 1C is X(A). If discharged with a current of 2X(A), then 2C If it was discharged with a current of X / 5(A), then it was discharged at 0.2C. It is said that the charging rate is also similar; if charged with a current of 2X(A), it will charge at 2C. They said they charged it, and if they charged it with a current of X / 5(A), they said they charged it at 0.2C. .

[0098] (Embodiment 4) In this embodiment, the active material particles 10 function as the positive electrode active material as described in the previous embodiment. Examples of materials that can be used in secondary batteries having 0 will be described. We will explain this using a secondary battery as an example, in which the positive electrode, negative electrode, and electrolyte are enclosed in an outer casing.

[0099] [Positive electrode] The positive electrode comprises a positive electrode active material layer and a positive electrode current collector.

[0100] <Cathode active material layer> The positive electrode active material layer contains a positive electrode active material. Furthermore, the positive electrode active material layer contains a conductive additive and a binder. It may have.

[0101] As the positive electrode active material, active material particles 1 that function as the positive electrode active material described in the previous embodiment 00 can be used. Active material that functions as a positive electrode active material as described in the previous embodiment By using particle 100, a secondary battery with high capacity and excellent cycle characteristics can be made. .

[0102] As conductive additives, carbon materials, metal materials, or conductive ceramic materials can be used. Yes, it is possible. Additionally, fibrous materials may be used as conductive additives. The conductivity relative to the total amount of the active material layer... The content of the electrolytic agent is preferably 1 wt% to 10 wt%, and preferably 1 wt% to 5 wt%. This is preferable.

[0103] Conductive additives can be used to form an electrical conduction network within the active material layer. The agent can maintain the electrical conduction pathway between the positive electrode active materials. By adding an electro-enhancing agent, it is possible to create an active material layer with high electrical conductivity. .

[0104] Examples of conductive additives include natural graphite, artificial graphite such as mesocarbon microbeads, and carbon fibers. Fibers can be used. For example, mesophase pitch carbon fibers can be used. Carbon fibers such as isotropic pitch carbon fibers can be used. Carbon nanofibers and carbon nanotubes can be used. The tubes can be fabricated, for example, by vapor phase growth. Also, as a conductive additive, for example... Examples include carbon black (acetylene black (AB), etc.) and graphite particles. Carbon materials such as graphene and fullerene can be used. Also, for example, copper, nickel Metal powders such as oxal, aluminum, silver, and gold, as well as metal fibers and conductive ceramic materials. It can be used.

[0105] Furthermore, graphene compounds may be used as conductive additives.

[0106] Graphene compounds possess excellent electrical properties, including high conductivity, as well as high flexibility and high It possesses excellent physical properties, such as high mechanical strength, and may also have other properties. The compound has a planar shape. Graphene compounds enable surface contact with low contact resistance. Furthermore, even thin materials can have very high conductivity, allowing for efficient conduction within the active material layer with only a small amount. An electric current can be formed. Therefore, graphene compounds can be used as conductive additives. This is preferable because it increases the contact area between the active material and the conductive additive. This is preferable because it can reduce electrical resistance. Here, graphene compounds are used as an example. For example, graphene or multigraphene or reduced graphene O It is particularly preferable to use xide (hereinafter referred to as RGO). Here, RGO is, for example, oxidation This refers to compounds obtained by reducing graphene (graphene oxide: GO).

[0107] When using active materials with small particle sizes, for example, active materials with a particle size of 1 μm or less, the specific surface area of ​​the active material is Larger materials require more conductive paths to connect the active materials. Therefore, a larger amount of conductive additive is needed. This tends to happen, and relatively, the amount of active material carried decreases. When this decreases, the capacity of the secondary battery decreases. In such cases, a conductive additive is used. When graphene compounds are used, even small amounts of graphene compounds efficiently form conductive paths. This is particularly preferable because it does not require reducing the amount of active material supported.

[0108] In the following example, a graphene compound is used as a conductive additive in the active material layer 200. An example of the cross-sectional configuration will be explained.

[0109] Figure 11(A) shows a longitudinal cross-sectional view of the active material layer 200. The active material layer 200 consists of active material particles 10 It comprises 0, a graphene compound 201 as a conductive additive, and a binder (not shown). Here, graphene compound 201 can be used, for example, as graphene or multigraphene. This is sufficient. Here, it is preferable that the graphene compound 201 has a sheet-like shape. Furthermore, graphene compound 201 is composed of multiple multigraphenes or multiple graphenes. It may be partially overlapping and form a sheet. Also, graphene compound 201 may have multiple markers. Even if both tigraphene and multiple graphenes are partially overlapping and form a sheet, stomach.

[0110] In the longitudinal section of the active material layer 200, as shown in Figure 11(A), the interior of the active material layer 200 In this, the sheet-like graphene compound 201 is dispersed in a generally uniform manner. Figure 11(A) Here, graphene compound 201 is schematically represented by a thick line, but in reality, it is a single layer of carbon molecules or It is a thin film with multiple layers and thickness. Multiple graphene compounds 201 are multiple active material particles It encloses, covers, or adheres to the surface of multiple active material particles 100. Because they are formed in such a way, they are in surface contact with each other.

[0111] Here, multiple graphene compounds bond together to form a network of graphene compounds. Forming a sheet (hereinafter referred to as graphene compound net or graphene net) Yes, it is possible. When the active material is covered with a graphene net, the graphene net connects the active materials to each other. It can also function as a binder. Therefore, it reduces the amount of binder needed. Because it is possible to do so or not to use it, the ratio of active material to electrode volume or electrode weight The efficiency can be improved. In other words, the capacity of the secondary battery can be increased.

[0112] Here, graphene oxide is used as graphene compound 201 and mixed with the active material to form the active material It is preferable to reduce the layer after forming the layer that will become layer 200. By using graphene oxide, which has extremely high dispersibility in polar solvents, graphene formation can be achieved. The compound 201 can be dispersed approximately uniformly within the active material layer 200. The solvent is volatilized and removed from the dispersion medium containing dispersed graphene oxide, and the graphene oxide is reduced. Therefore, the graphene compound 201 remaining in the active material layer 200 partially overlaps, and By being dispersed to the extent that they are in surface contact, a three-dimensional conductive path can be formed. The reduction of graphene oxide may be carried out, for example, by heat treatment or by using a reducing agent. That's fine.

[0113] Therefore, unlike granular conductive additives such as acetylene black that make point contact with the active material, graph Compound 201 enables surface contact with low contact resistance, unlike conventional conductive additives. To improve the electrical conductivity between the active material particles 100 and the graphene compound 201 using only a small amount. Therefore, it is possible to increase the ratio of active material particles 100 in the active material layer 200. Yes, it is possible. This allows for an increase in the discharge capacity of the energy storage device.

[0114] Examples of binders include styrene-butadiene rubber (SBR) and styrene-isoprene rubber. N-styrene rubber, acrylonitrile-butadiene rubber, butadiene rubber, ethylene- It is preferable to use a rubber material such as a propylene-diene copolymer. Fluororubber can be used.

[0115] Furthermore, it is preferable to use a water-soluble polymer as the binder. For example, polysaccharides can be used as the derivative. Cellulose (CMC), methylcellulose, ethylcellulose, hydroxypropylcellulose Cellulose derivatives such as lurose, diacetylcellulose, and regenerated cellulose, as well as starch, etc. These can be used. Furthermore, these water-soluble polymers can be used in combination with the aforementioned rubber materials. It would be even better if they were there.

[0116] Alternatively, as a binder, polystyrene, polymethyl acrylate, polymethyl methacrylate can be used. Chill (PMMA), sodium polyacrylate, polyvinyl alcohol (PVA), poly Ethylene oxide (PEO), polypropylene oxide, polyimide, polyvinyl chloride, Polytetrafluoroethylene, polyethylene, polypropylene, polyisobutylene, poly Ethylene terephthalate, nylon, polyvinylidene fluoride (PVdF), polyacrylo Nitrile (PAN), ethylene propylene diene polymer, polyvinyl acetate, nitrocellulose It is preferable to use ingredients such as loin.

[0117] You may use a combination of several of the binders mentioned above.

[0118] For example, a material with particularly excellent viscosity-modifying properties may be used in combination with other materials. For example, rubber materials have excellent adhesive and elastic properties, but their viscosity is difficult to adjust when mixed with a solvent. In such cases, for example, mixing with a material that has particularly excellent viscosity-modifying effects may be used. This is preferable. As a material with particularly excellent viscosity adjustment effect, for example, a water-soluble polymer can be used. Furthermore, water-soluble polymers that are particularly excellent in viscosity adjustment include the aforementioned polysaccharides, for example, calcium carbonate. Voxymethylcellulose (CMC), methylcellulose, ethylcellulose, hydroxy Cellulose derivatives such as propylcellulose, diacetylcellulose, and regenerated cellulose. Body or starch can be used.

[0119] Furthermore, cellulose derivatives such as carboxymethylcellulose are, for example, carboxymethyl By using salts such as sodium salts or ammonium salts of cellulose, the solubility increases. It becomes easier to exert its effect as a viscosity modifier. The increased solubility makes the electrode slurry - When manufacturing, it is also possible to improve the dispersibility with the active material and other components. As for cellulose and cellulose derivatives used as electrode binders, This also includes salt.

[0120] Water-soluble polymers stabilize viscosity by dissolving in water, and also function as active materials and binders. Other materials to be combined with it, such as styrene-butadiene rubber, are stably separated in an aqueous solution. It can be dispersed. Furthermore, because it has functional groups, it is easily and stably adsorbed onto the surface of the active material. This is expected. Also, cellulose derivatives such as carboxymethylcellulose, For example, many materials have functional groups such as hydroxyl groups and carboxyl groups, and because they have functional groups It is expected that the polymers will interact with each other and exist to broadly cover the surface of the active material.

[0121] When a binder covering or in contact with the surface of the active material forms a film, it is considered a passivation film. It is also expected to play a role in suppressing the decomposition of the electrolyte. Here, the passive film is an electrolytic film. It is a film with no electron conductivity or extremely low electrical conductivity. For example, when a passive film is formed on the surface of an active material , decomposition of the electrolytic solution can be suppressed at the battery reaction potential . Further, it is more preferable that the passive film suppresses electrical conductivity while allowing lithium ions to conduct .

[0122] <Positive electrode current collector> As the positive electrode current collector, materials with high conductivity can be used, such as metals including stainless steel, gold, platinum, aluminum and titanium, as well as alloys of these metals. It is preferable that the material used for the positive electrode current collector does not elute at the potential of the positive electrode. In addition, aluminum alloys added with elements that improve heat resistance such as silicon, titanium, neodymium, scandium and molybdenum can be used . It may also be formed of a metal element that reacts with silicon to form silicide . Examples of the metal element that reacts with silicon to form silicide include zirconium, titanium , hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten , cobalt, nickel, etc. The current collector can be appropriately used in shapes such as foil, plate (sheet), mesh, punched metal, expanded metal and the like. It is preferable to use a current collector having a thickness of 5 µm or more and 30 µm or less.

[0123] [Negative electrode] The negative electrode has a negative electrode active material layer and a negative electrode current collector. In addition, the negative electrode active material layer may contain a conductive additive and a binder.

[0124] <Negative electrode active material> As the negative electrode active material, for example, alloy-based materials, carbon-based materials and the like can be used.

[0125] As a negative electrode active material, it is possible to perform charge and discharge reactions through alloying and dealloying reactions with lithium. Any suitable element can be used. For example, silicon, tin, gallium, aluminum, galvanic acid. Among the following, a small amount is found in luminum, lead, antimony, bismuth, silver, zinc, cadmium, indium, etc. Materials containing at least one element can be used. Such elements have a larger capacity compared to carbon. In particular, silicon has a high theoretical capacity of 4200mAh / g. Therefore, silicon is used as the negative electrode active material. It is preferable to use lycon. Alternatively, compounds containing these elements may be used. Example For example, SiO, Mg2Si, Mg2Ge, SnO, SnO2, Mg2Sn, SnS2, V 2Sn3, FeSn2, CoSn2, Ni3Sn2, Cu6Sn5, Ag3Sn, Ag3 Sb, Ni2MnSb, CeSb3, LaSn3, La3Co2Sn7, CoSb3, I Examples include nSb and SbSn. Here, the charge-discharge reaction occurs through alloying and dealloying reactions with lithium. Elements capable of performing this action, and compounds containing such elements, are sometimes referred to as alloying materials. ru.

[0126] In this specification, SiO refers to silicon monoxide, for example. Alternatively, SiO refers to SiO x It can also be expressed as follows. Here, it is preferable that x has one neighboring value. For example, x is 0 A value of 0.2 to 1.5 is preferred, and a value of 0.3 to 1.2 is more preferred.

[0127] Carbon-based materials include graphite, easily graphitizable carbon (soft carbon), and poorly graphitizable carbon (hard carbon). Carbon, carbon nanotubes, graphene, carbon black, etc. can be used. .

[0128] Examples of graphite include synthetic graphite and natural graphite. An example of synthetic graphite is Mesoca. Examples include carbon 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. Furthermore, MCMB may have a spherical shape, which is preferable. Also, the surface area of ​​MCMB Reducing the size is relatively easy and sometimes preferable. Examples of natural graphite include, Examples include flaky graphite and spheroidized natural graphite.

[0129] Graphite is formed when lithium ions are inserted into it (during the formation of lithium-graphite intercalation compounds). It exhibits a low potential, similar to lithium metal (0.05V to 0.3V vs. Li / L). i + This allows lithium-ion secondary batteries to exhibit a high operating voltage. Furthermore, graphite has a relatively high capacity per unit volume, relatively small volume expansion, and is inexpensive. It is preferable because it has advantages such as higher safety compared to lithium metal.

[0130] Furthermore, titanium dioxide (TiO2) and lithium titanium oxide (Li4T) are used as negative electrode active materials. i5O 12 ), lithium-graphite intercalation compound (Li x C6), Niobium pentoxide (Nb2O5) Oxides such as tungsten oxide (WO2) and molybdenum oxide (MoO2) can be used. can.

[0131] Furthermore, the negative electrode active material has a Li3N-type structure, which is a lithium and transition metal binitride. Li 3-x M x N (M = Co, Ni, Cu) can be used. For example, Li 2.6 Co 0.4 The N3 has a large charge / discharge capacity (900mAh / g, 1890mAh / cm²). 3) shows , which is preferable.

[0132] When a double nitride of lithium and a transition metal is used, since the negative electrode active material contains lithium ions, it can be combined with materials that do not contain lithium ions such as V2O5 and Cr3O8 as the positive electrode active material , which is preferable. Even when a material containing lithium ions is used as the positive electrode active material, by pre-desorbing lithium ions contained in the positive electrode active material, a double nitride of lithium and a transition metal can be used as the negative electrode active material.

[0133] Further, a material that causes a conversion reaction can also be used as the negative electrode active material. For example, transition metal oxides that do not form an alloy with lithium, such as cobalt oxide (CoO), nickel oxide (NiO), and iron oxide (FeO), may be used as the negative electrode active material. Examples of materials that cause a conversion reaction further include Fe2O3, CuO, Cu2O, RuO2, Cr2O3 and other oxides, CoS 0.89 , sulfides such as NiS and CuS, nitrides such as Zn3N2, Cu3N and Ge3 N4, phosphides such as NiP2, FeP2 and CoP3, and fluorides such as FeF3 and BiF3 also cause the conversion reaction.

[0134] As the conductive aid and binder that can be contained in the negative electrode active material layer, the same materials as the conductive aid and binder that can be contained in the positive electrode active material layer can be used.

[0135] <Negative Electrode Current Collector> The same materials as for the positive electrode current collector can be used for the negative electrode current collector. It is preferable that the negative electrode current collector be made of a material that does not alloy with carrier ions such as lithium.

[0136] [Electrolyte solution] An electrolyte solution contains a solvent and an electrolyte. A non-protic organic solvent is preferred as the solvent for the electrolyte solution. For example, ethylene carbonate (EC), propylene carbonate (PC), and buty Lenyl carbonate, chloroethylene carbonate, vinylene carbonate, γ-butyrolane Chtone, γ-valerolactone, dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), methyl formate, methyl acetate, ethyl acetate Methyl propionate, ethyl propionate, propyl propionate, methyl butyrate, 1 ,3-dioxane, 1,4-dioxane, dimethoxyethane (DME), dimethyl sulfone Hoxide, diethyl ether, methyl diglyme, acetonitrile, benzonitrile, tetra One of the following: lahydrofuran, sulfolane, sultone, or two or more of these. It can be used in combinations and ratios.

[0137] Furthermore, as the solvent for the electrolyte, an ionic liquid (a room-temperature molten salt) that is flame-retardant and non-volatile is used. By using one or more of these, the internal temperature of the energy storage device will rise due to internal short circuits or overcharging. This can also prevent the rupture or ignition of energy storage devices. Ionic liquids contain cations and anions. It consists of organic cations and anions. As organic cations used in the electrolyte, quaternary cations are used. Ammonium cations, tertiary sulfonium cations, and quaternary phosphonium cations, etc. aliphatic onium cations, imidazolium cations, 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.

[0138] Furthermore, examples of electrolytes to be dissolved in the above solvent include LiPF6, LiClO4, and LiA. sF6, LiBF4, LiAlCl4, LiSCN, LiBr, LiI, Li2SO4, Li2B 10 Cl 10 Li2B 12 Cl 12 LiCF3SO3, LiC4F9SO3 , LiC(CF3SO2)3, LiC(C2F5SO2)3, LiN(CF3SO2)2 Lithium, such as LiN(C4F9SO2)(CF3SO2), LiN(C2F5SO2)2 One type of salt, or two or more of these in any combination and ratio, may be used. can.

[0139] The electrolyte used in the energy storage device may contain particulate matter and elements other than the constituent elements of the electrolyte (hereinafter simply referred to as "non-contaminated"). It is preferable to use a highly purified electrolyte with a low content of (also called "pure substance"). Specifically, the weight ratio of impurities to the electrolyte should be 1% or less, preferably 0.1% or less, more preferably It is preferable that the amount be 0.01% or less.

[0140] Furthermore, the electrolyte contains vinylene carbonate, propanesultone (PS), and tert-butylbe. TBB, fluoroethylene carbonate (FEC), LiBOB, and also succinyl Dinitrile compounds such as notrile and adiponitrile may be added. The concentration should be, for example, between 0.1 wt% and 5 wt% relative to the total solvent.

[0141] Alternatively, a polymer gel electrolyte, obtained by swelling a polymer with an electrolyte solution, may be used. Using an electrolyte increases safety against leakage, etc. Furthermore, it allows for the miniaturization of secondary batteries. It can be made lighter.

[0142] Examples of polymers that can be gelled include silicone gel, acrylic gel, and acrylonitrile gel. Polyethylene oxide gels, polypropylene oxide gels, fluorine polymers Gels and the like can be used. Examples of polymers include polyethylene oxide (PEO Polymers having a polyalkylene oxide structure such as PVDF and polyacrylic Lenitriles and the like, and copolymers containing them, can be used. For example, PVDF and Using PVDF-HFP, a copolymer of hexafluoropropylene (HFP) Yes, it is possible. Furthermore, the resulting polymer may have a porous structure.

[0143] In addition, instead of an electrolyte, a solid electrolyte containing inorganic materials such as sulfide-based or oxide-based materials, or P Solid electrolytes containing polymer materials such as EO (polyethylene oxide) can be used. When using a solid electrolyte, the installation of separators and spacers becomes unnecessary. Because the entire pond can be solidified, the risk of leakage is eliminated, dramatically improving safety.

[0144] [Separator] Furthermore, it is preferable that the secondary battery has a separator. The separator can be, for example, paper. Fibers containing cellulose, nonwoven fabrics, glass fibers, ceramics, or other materials. Iron (polyamide), Vinylon (polyvinyl alcohol-based fiber), polyester, acrylic Made from synthetic fibers such as lyl, polyolefin, and polyurethane. This can be done. The separator is processed into an envelope shape and encloses either the positive or negative electrode. It is preferable to arrange them in this manner.

[0145] The separator may have a multilayer structure. For example, an organic material such as polypropylene or polyethylene. The material film contains ceramic-based materials, fluorine-based materials, polyamide-based materials, or a combination thereof. Mixtures and other materials can be coated onto it. Examples of ceramic materials include aluminium 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.

[0146] Coating with ceramic materials improves oxidation resistance, thus preventing separation during high-voltage charging and discharging. This can suppress degradation of the battery and improve the reliability of secondary batteries. Furthermore, by using fluorine-based materials... This allows the separator and electrodes to adhere more closely, improving the output characteristics. Coating with polyamide materials, especially aramid, improves heat resistance, thus increasing the safety of secondary batteries. It can improve overall health.

[0147] For example, a mixture of aluminum oxide and aramid material is applied to both sides of a polypropylene film. It may also be done by applying aluminum oxide to the surface of the polypropylene film that is in contact with the positive electrode. A mixed material of um and aramid may be coated, and a fluorine-based material may be coated on the surface in contact with the negative electrode. .

[0148] Using a multilayer separator ensures the safety of the secondary battery even if the overall thickness of the separator is thin. Because it can maintain this state, the capacity per unit volume of a secondary battery can be increased.

[0149] [Exterior] For the casing of a secondary battery, metal materials such as aluminum or resin materials are used. It is possible to use a film-like outer covering. As for the film, For example, polyethylene, polypropylene, polycarbonate, ionomer, polyamide, etc. A film made of the following materials, with highly flexible gold such as aluminum, stainless steel, copper, and nickel. A thin metal film is provided, and on the metal thin film, a polyamide resin and polyester resin are used as the outer surface of the exterior body. A three-layer film with an insulating synthetic resin film, such as a ru-based resin, can be used.

[0150] (Embodiment 5) [Cylindrical rechargeable battery] In this embodiment, an example of a cylindrical secondary battery will be described with reference to Figure 12. As shown in Figure 12(A), the secondary battery 600 has a positive electrode cap (battery cover) 601 on its top surface. It has a battery can (outer casing) 602 on its side and bottom. These positive electrode cap and battery The battery container (outer container) 602 is insulated by the gasket (insulating packing) 610. .

[0151] Figure 12(B) is a schematic diagram showing a cross-section of a cylindrical secondary battery. Inside can 602, a strip-shaped positive electrode 604 and a negative electrode 606 are separated by a separator 605. A wound battery element is provided. Although not shown in the diagram, the battery element is centered around the center pin. It is wound up. Battery can 602 is closed at one end and open at the other end. This is a metal such as nickel, aluminum, or titanium that is corrosion-resistant to the electrolyte, or this These alloys or alloys of these with other metals (for example, stainless steel) can be used. Furthermore, to prevent corrosion from the electrolyte, it is preferable to coat the components with nickel, aluminum, etc. Inside the battery can 602, the positive electrode, negative electrode, and separator are wound together to form a battery element. It is sandwiched between a pair of opposing insulating plates 608 and 609. Furthermore, a battery element is provided. The inside of the battery can 602 is filled with a non-aqueous electrolyte (not shown). The non-aqueous electrolyte is A battery similar to a coin-type rechargeable battery can be used.

[0152] 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 positive electrode 604 is connected to the positive electrode terminal (positive electrode current collector lead) 603, and the negative electrode The negative terminal (negative current collector lead) 607 is connected to 606. Positive terminal 603 and negative terminal Terminals 607 can both be made of metal materials such as aluminum. Positive terminal 60 Terminal 3 is resistance-welded to the safety valve mechanism 612, and the negative terminal 607 is resistance-welded to the bottom of the battery can 602. The safety valve mechanism 612 is a PTC element (Positive Temperature Coefficient). It is electrically connected to the positive electrode cap 601 via the efficient 611. The valve mechanism 612, when the rise in the internal pressure of the battery exceeds a predetermined threshold, and the positive electrode cap 601 and This disconnects the electrical connection with the positive electrode 604. Also, the PTC element 611 is at a higher temperature. This is a thermal resistance element whose resistance increases when the temperature rises, and by increasing the resistance, it limits the amount of current. This prevents overheating. The PTC element uses a barium titanate (BaTiO3) semiconductor. Conductive ceramics and the like can be used.

[0153] Furthermore, as shown in Figure 12(C), multiple secondary batteries 600 are connected to conductive plates 613 and 614 Module 615 may be configured by sandwiching it between them. Multiple secondary batteries 600 are connected in parallel. They may be connected in series, or connected in parallel and then further connected in series. It may be done. By configuring a module 615 having multiple secondary batteries 600, It can extract a large amount of power.

[0154] Figure 12(D) is a top view of module 615. The conductive plate 613 is shown in the diagram for clarity. This is shown by the dotted line. As shown in Figure 12(D), module 615 has multiple secondary batteries 600 It may have electrically connected conductors 616. A conductive plate may be superimposed on the conductors 616. It is possible to have a temperature control device 617 between multiple secondary batteries 600. i. When the secondary battery 600 overheats, the temperature control device 617 cools it down, and the secondary battery 6 When 00 is too cold, it can be heated by the temperature control device 617. The performance of module 615 will be less affected by ambient temperature.

[0155] The positive electrode 604 is provided with active material particles 100 that function as the positive electrode active material described in the previous embodiment. By using this, it is possible to create a cylindrical secondary battery 600 with high capacity and excellent cycle characteristics. ru.

[0156] [Example of a secondary battery structure] Another example of a secondary battery structure will be explained using Figures 13 to 16.

[0157] Figures 13(A) and 13(B) show the external view of the battery pack. The battery pack is It has a circuit board 900 and a secondary battery 913. The secondary battery 913 has terminals 951 and terminals It has a child 952 and is covered with a label 910. The battery pack also has an antenna 914. You may do so.

[0158] The circuit board 900 is secured with a seal 915. The circuit board 900 has a circuit 912. Terminal 911 is connected to terminal 951 and terminal 913 of the secondary battery 913 via the circuit board 900. It is electrically connected to terminal 952. Also, terminal 911 is connected to the antenna via circuit board 900. It is electrically connected to terminal 914 and circuit 912. Note that multiple terminals 911 are provided, and multiple Each of the terminals 911 may be used as a control signal input terminal, a power supply terminal, etc.

[0159] Circuit 912 protects the secondary battery 913 from overcharging, over-discharging, and overcurrent, for example. It functions as a protective circuit. Circuit 912 is provided on the back surface of circuit board 900. That's good. Note that the antenna 914 is not limited to a coil shape; it may also be linear, plate-shaped, etc. Also, planar antennas, aperture antennas, traveling wave antennas, EH antennas, magnetic field antennas Antennas such as dielectric antennas may also be used. Antenna 914 may be, for example, an external device It has the function to communicate data with the battery pack via antenna 914. Communication methods with other devices include NFC, which is used between the battery pack and other devices. A response method that allows for this can be applied.

[0160] The battery pack has a layer 916 between the antenna 914 and the secondary battery 913. For example, it has the function of preventing the secondary battery 913 from affecting the electromagnetic field. For layer 916, for example, a magnetic material can be used.

[0161] Note that the structure of the battery pack is not limited to that shown in Figure 13.

[0162] For example, as shown in Figures 14(A-1) and 14(A-2), Figures 13(A) and 13 Even if an antenna 918 is provided on the other opposing side of the secondary battery 913 shown in (B) Good. Figure 14(A-1) is an external view of the pair of surfaces as seen from one side, and Figure 14( A-2) is an external view of the pair of surfaces as seen from the other side. Note that Figure 13(A) and For the same parts as the battery pack shown in Figure 13(B), see Figures 13(A) and 13(B). The battery pack description shown can be used as appropriate.

[0163] As shown in Figure 14(A-1), a layer 916 is sandwiched between one of the pair of surfaces of the secondary battery 913. An inlet 914 is provided, and as shown in Figure 14(A-2), a pair of sides of the secondary battery 913 On the other side, an antenna 918 is provided with a layer 917 in between. Layer 917 is, for example, a secondary battery 91 It has the function of preventing the influence of 3 on the electromagnetic field. As for layer 917, for example A magnetic material can be used.

[0164] By adopting the above structure, the battery pack is provided with two antennas, and antenna 914 and Both sizes of the 918 antenna can be increased.

[0165] Antenna 918 can be fitted with an antenna of a shape applicable to antenna 914. Furthermore, the antenna 918 may be a flat conductor. This flat conductor is a conductor for electric field coupling. It can function as one of the components. That is, one of the two conductors that a capacitor has. Antenna 914 may function as a single conductor. This allows only electromagnetic and magnetic fields to be generated. Alternatively, power can be exchanged using an electric field.

[0166] Alternatively, as shown in Figure 14(B-1), the battery packs shown in Figures 13(A) and 13(B) may be used. A display device 920 may be provided. The display device 920 is electrically connected to terminal 911. Note that the same parts as the battery pack shown in Figures 13(A) and 13(B) are shown in Figure 13. The explanation of the battery pack shown in (A) and Figure 13(B) can be used as appropriate.

[0167] The display device 920 displays, for example, an image indicating whether or not it is charging, an image indicating the amount of stored power, etc. It may be shown. The display device 920 may be, for example, electronic paper, liquid crystal display device, or electronic A luminescent (also known as EL) display device can be used. For example, an electronic paper By using this method, the power consumption of the display device 920 can be reduced.

[0168] Alternatively, as shown in Figure 14(B-2), the secondary battery 9 shown in Figures 13(A) and 13(B) A sensor 921 may be provided at 13. The sensor 921 is connected to terminal 922 and circuit board 900. It is electrically connected to terminal 911 via [this]. Note that as shown in Figures 13(A) and 13(B) For parts identical to the energy storage device, see the explanation of the energy storage device shown in Figures 13(A) and 13(B). It can be used as appropriate.

[0169] Examples of sensors 921 include displacement, position, velocity, acceleration, angular velocity, rotational speed, distance, and light. Liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, electric current, voltage, power, radiation, flow It should have the ability to measure quantity, humidity, gradient, vibration, odor, or infrared radiation. By providing the sensor 921, for example, data indicating the environment in which the energy storage device is located can be collected. It can also detect (temperature, etc.) and store it in the memory within circuit 912.

[0170] Furthermore, an example of the structure of the secondary battery 913 will be explained using Figures 15 and 16.

[0171] The secondary battery 913 shown in Figure 15(A) has terminals 951 and 952 inside the housing 930. It has a wound body 950. The wound body 950 is impregnated with an electrolyte inside the housing 930. Terminal 952 is in contact with the housing 930, and terminal 951 is in contact with the housing by using insulating material, etc. It is not in contact with the body 930. Note that in Figure 15(A), for convenience, the housing 930 is separated. As shown in the diagram, in reality the wound body 950 is covered by the housing 930, and terminals 951 and 95 2 extends outside the casing 930. The casing 930 is made of a metal material (e.g., aluminum). Materials such as lum or resin can be used.

[0172] Furthermore, as shown in Figure 15(B), the housing 930 shown in Figure 15(A) is made of multiple materials. They may be formed. For example, the secondary battery 913 shown in Figure 15(B) has a housing 930a and a housing 9 30b is bonded together, and the area enclosed by the housing 930a and housing 930b is wound up 9 50 is provided.

[0173] For the casing 930a, insulating materials such as organic resin can be used. In particular, the antenna By using a material such as organic resin on the surface where the electric field of the secondary battery 913 is formed, Shielding can be suppressed. Furthermore, if the shielding of the electric field by the housing 930a is small, the housing 930a An antenna such as antenna 914 may be provided inside. The housing 930b may be, for example, made of gold. The material can be used.

[0174] Furthermore, the structure of the wound body 950 is shown in Figure 16. The wound body 950 consists of a negative electrode 931 and a positive electrode. It has poles 932 and separators 933. The coiled body 950 sandwiches the separators 933. The negative electrode 931 and the positive electrode 932 are stacked on top of each other, and the stacked sheet is wound up to form a wound body. Furthermore, the stacking of the negative electrode 931, the positive electrode 932, and the separator 933 is further multiplied. You can do it multiple times.

[0175] The negative electrode 931 is connected to terminal 911 shown in Figure 13 via either terminal 951 or terminal 952. The positive terminal 932 is connected to terminal 91 shown in Figure 13 via terminal 951 and the other terminal 952. It connects to 1.

[0176] The positive electrode 932 is provided with active material particles 100 that function as the positive electrode active material described in the previous embodiment. By using this, a secondary battery 913 with high capacity and excellent cycle characteristics can be created.

[0177] (Embodiment 6) This embodiment describes an example in which a secondary battery, which is one aspect of the present invention, is mounted in an electronic device. do.

[0178] First, as an electronic device that uses a rechargeable battery, for example, a television set (television, or television) (also called a revision receiver), monitors for computers, digital cameras, digital Video cameras, digital photo frames, mobile phones (also called mobile phones or mobile phone devices) ), portable game consoles, personal digital assistants, audio playback devices, large game machines such as pachinko machines, etc. These are some examples.

[0179] Next, Figures 17(A) and 17(B) show an example of a foldable tablet device. The tablet terminal 9600 shown in Figures 17(A) and 17(B) has a housing 9630. a, housing 9630b, movable part 9640 connecting housing 9630a and housing 9630b, display Section 9631, display mode switching switch 9626, power switch 9627, power saving mode It has a toggle switch 9625, a fastener 9629, and an operating switch 9628. Section 9631 uses a flexible panel, allowing for a tablet with a wider display area. It can be used as a tablet terminal. Figure 17(A) shows the tablet terminal 9600 in an open state. Figure 17(B) shows the tablet terminal 9600 in the closed position.

[0180] Furthermore, the tablet terminal 9600 stores energy inside the housings 9630a and 9630b. It has a body 9635. The energy storage body 9635 passes through the movable part 9640 and the housing 9630a and housing It is located across 9630b.

[0181] The display unit 9631 can be partially designated as a touch panel area, and the displayed operation keys can be accessed. Data can be entered by touching the screen. Additionally, the touchscreen keyboard display can be turned off. By touching the location where the replacement button is displayed with your finger or stylus, the display unit 9631 will activate. Keyboard buttons can be displayed.

[0182] Additionally, the display mode switch 9626 switches the display orientation, such as portrait or landscape. You can switch between black and white and color displays. Power saving mode switch. The 9625 is detected by the light sensor built into the tablet terminal 9600 when in use. The display brightness can be optimized according to the amount of ambient light. In addition to optical sensors, other detection sensors such as gyroscopes and accelerometers that detect tilt are also used. The device may be built-in.

[0183] Figure 17(B) shows the closed state, and the tablet terminal consists of a housing 9630 and a solar cell 96 33. It has a charge / discharge control circuit 9634 including a DC-DC converter 9636. Also, an energy storage unit As 9635, a secondary battery according to one aspect of the present invention is used.

[0184] Furthermore, since the tablet device 9600 is foldable, when not in use, the casing 9630a and The casing 9630b can be folded so that it overlaps with the other casing. By folding it, Since the display unit 9631 can be protected, the durability of the tablet terminal 9600 can be increased. It can. Furthermore, the energy storage unit 9635 using a secondary battery according to one aspect of the present invention has high capacity and good cycle Because it possesses certain characteristics, the tablet terminal 9600 can be used for extended periods of time. We can provide it.

[0185] In addition, the tablet devices shown in Figures 17(A) and 17(B) are also available in various forms. Functions to display information (still images, videos, text images, etc.), calendar, date or time, etc. A function to display information on the display unit, and a touch input operation or editing of the information displayed on the display unit. It has input capabilities, and functions to control processing through various software (programs), etc. It is possible.

[0186] The touch panel is powered by a solar cell 9633 mounted on the surface of the tablet device. It can be supplied to the display unit or the video signal processing unit, etc. Note that the solar cell 9633 is housed in a casing. A structure that can be provided on one or both sides of the body 9630 and efficiently charges the energy storage body 9635. It can be considered a success.

[0187] Furthermore, the configuration and operation of the charge / discharge control circuit 9634 shown in Figure 17(B) are shown in Figure 17( A block diagram is shown and explained in C). Figure 17(C) shows the solar cell 9633 and the energy storage unit 963. 5. DC-DC converter 9636, converter 9637, switch SW1 to SW3, table The diagram shows the section 9631, and includes the energy storage unit 9635, the DC-DC converter 9636, and the capacitor. The converter 9637 and switches SW1 to SW3 are connected to the charge / discharge control circuit 96 shown in Figure 17(B). This corresponds to section 34.

[0188] First, let's explain an example of operation when electricity is generated by the solar cell 9633 using ambient light. The electricity generated by the solar panel is converted to a DC-DC converter to provide the voltage needed to charge the 9635 energy storage unit. The converter 9636 performs voltage boosting or de-voltage adjustment. Then, the solar cell controls the operation of the display unit 9631. When power from 9633 is used, switch SW1 is turned ON, and converter 9637 The voltage is then boosted or lowered to the voltage required for the display unit 9631. If you do not want the display to appear, turn SW1 off and SW2 on to charge the battery 9635. The configuration should be designed to handle electricity.

[0189] The solar cell 9633 is shown as an example of a power generation method, but it is not particularly limited to this method. Energy storage using other power generation methods such as electrical elements (piezo elements) and thermoelectric conversion elements (Peltier elements) The configuration may also involve charging the body 9635. For example, power may be transmitted and received wirelessly (contactlessly). This configuration uses a contactless power transmission module for charging, or a combination of other charging methods. That's fine.

[0190] Figure 18 shows an example of another electronic device. In Figure 18, the display device 8000 is part of the present invention. This is an example of an electronic device using a secondary battery 8004 according to the embodiment. Specifically, the display device 800 0 corresponds to a display device for receiving TV broadcasts, and consists of a housing 8001, a display unit 8002, and a speaker unit. The invention includes 8003, a secondary battery 8004, etc. A secondary battery 8004 according to one aspect of the present invention has a housing It is located inside the body 8001. The display device 8000 receives power from the commercial power supply. It can be used to power the device, or it can use the power stored in the secondary battery 8004. Even when power cannot be supplied from the commercial power source due to a power outage, etc., according to one aspect of the present invention By using the secondary battery 8004 as an uninterruptible power supply, the display device 8000 can be used. ru.

[0191] The display unit 8002 has light-emitting elements such as liquid crystal display devices and organic EL elements in each pixel. Equipment, electrophoresis display device, DMD (Digital Micromirror Display) ce), PDP (Plasma Display Panel), FED (Field Semiconductor display devices such as Emission Displays can be used.

[0192] In addition to being used for receiving TV broadcasts, display devices are also used for personal computers, advertising displays, and more. This includes all information display devices.

[0193] In Figure 18, the fixed lighting device 8100 is a secondary battery 81 according to one aspect of the present invention. This is an example of an electronic device using 03. Specifically, the lighting device 8100 has a housing 8101 and light It has a power source 8102, a secondary battery 8103, etc. In Figure 18, the secondary battery 8103 is located in the housing 81 An example is provided where 01 and the light source 8102 are installed inside the ceiling 8104. However, the secondary battery 8103 may also be located inside the housing 8101. The 8100 can receive power from the commercial power supply, or it can store power in the secondary battery 8103. It is also possible to use the accumulated power. Therefore, if power is not supplied from the commercial power source due to a power outage, etc. Even when it is not possible to receive a power supply, the secondary battery 8103 according to one aspect of the present invention can be used as an uninterruptible power supply. This makes it possible to use the lighting device 8100.

[0194] Figure 18 illustrates a fixed lighting device 8100 installed on the ceiling 8104. However, in one aspect of the present invention, the secondary battery is located in a location other than the ceiling 8104, for example, the side wall 8105, the floor 8 106, It can also be used in fixed lighting devices installed in windows 8107, etc., and on a tabletop It can also be used in lighting fixtures and other similar devices.

[0195] Furthermore, the light source 8102 can be an artificial light source that uses electricity to artificially produce light. Specifically, this includes incandescent light bulbs, discharge lamps such as fluorescent lamps, and light-emitting elements such as LEDs and organic EL elements. The element is an example of the artificial light source mentioned above.

[0196] In Figure 18, an air conditioner having an indoor unit 8200 and an outdoor unit 8204, This is an example of an electronic device using a secondary battery 8203 according to one aspect of the present invention. Specifically, indoor The unit 8200 includes a housing 8201, an air outlet 8202, a secondary battery 8203, etc. (See Figure 18) This example illustrates the case where the secondary battery 8203 is provided in the indoor unit 8200, but Battery 8203 may be located in the outdoor unit 8204. Alternatively, it may be located in the indoor unit 8200 and the outdoor unit. The secondary battery 8203 may be provided on both sides of the unit 8204. (Air conditioner) It can receive power from the commercial power supply, or from the electricity stored in the secondary battery 8203. It can also use force. In particular, both the indoor unit 8200 and the outdoor unit 8204 can use secondary batteries 82 If 03 is provided, when power cannot be supplied from the commercial power source due to a power outage, etc. Furthermore, by using the secondary battery 8203 according to one aspect of the present invention as an uninterruptible power supply, an air conditioner can be used. Conditioner can be used.

[0197] Note that Figure 18 shows a separate-type air conditioner consisting of an indoor unit and an outdoor unit. As an example, an integrated air conditioner has both the indoor and outdoor unit functions in a single housing. A secondary battery according to one aspect of the present invention can also be used in the conditioner.

[0198] In Figure 18, the electric refrigerator 8300 is powered by a secondary battery 8304 according to one aspect of the present invention. This is an example of the electronic equipment used. Specifically, the electric refrigerator 8300 consists of a casing 8301 and a refrigerator. It has a storage room door 8302, a freezer room door 8303, a secondary battery 8304, etc. In Figure 18, two The next battery 8304 is located inside the casing 8301. The electric refrigerator 8300 is, It can receive power from the commercial power supply, or it can use the power stored in the secondary battery 8304. It can also be used. Therefore, when power cannot be supplied from the commercial power source due to a power outage, etc. However, by using the secondary battery 8304 according to one aspect of the present invention as an uninterruptible power supply, electric cooling The 8300 freezer / refrigerator will become available for use.

[0199] Furthermore, during periods when electronic devices are not in use, especially the total amount of electricity that can be supplied by the commercial power source... Of these, during periods when the proportion of electricity actually used (called the electricity usage rate) is low, secondary By storing power in the battery, the rate of power consumption outside of the above-mentioned time period is suppressed. It is possible. For example, in the case of the electric refrigerator 8300, when the temperature is low, the refrigerator door 830 2. At night when the freezer door 8303 is not opened or closed, power is stored in the secondary battery 8304. And as the temperature rises, the refrigerator door 8302 and the freezer door 8303 are opened and closed. During the daytime, by using the secondary battery 8304 as an auxiliary power source, the daytime power usage rate It can be kept low.

[0200] In addition to the electronic devices described above, a secondary battery according to one aspect of the present invention can be mounted in any electronic device. According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved. Depending on the embodiment, a high-capacity secondary battery can be made, and thus the secondary battery itself can be made smaller and lighter. Therefore, a secondary battery, which is one aspect of the present invention, is described in this embodiment. By incorporating this into electronic devices, it is possible to create electronic devices that have a longer lifespan and are lighter in weight. This embodiment can be implemented in appropriate combination with other embodiments.

[0201] (Embodiment 7) This embodiment shows an example in which a secondary battery according to one aspect of the present invention is mounted on a vehicle.

[0202] When a secondary battery is installed in a vehicle, it becomes a hybrid electric vehicle (HEV), an electric vehicle (EV), or a hybrid electric vehicle. This will enable the realization of next-generation clean energy vehicles such as plug-in hybrid electric vehicles (PHEVs). .

[0203] Figure 19 illustrates a vehicle using a secondary battery, which is one embodiment of the present invention. Figure 19(A) The automobile 8400 shown is an electric vehicle that uses an electric motor as a power source for driving. Yes. Alternatively, an electric motor and an engine can be appropriately selected and used as the power source for propulsion. This is a hybrid vehicle that can achieve the following: By using one aspect of the present invention, the driving range can be extended. This makes it possible to realize a vehicle. In addition, the 8400 automobile has a secondary battery. The secondary battery is By arranging many small cylindrical rechargeable batteries, as shown in Figure 12, on the floor of the vehicle, That's fine. Also, a battery pack made by combining multiple secondary batteries as shown in Figure 20 is placed on the floor inside the vehicle. It may be installed as follows. The secondary battery not only drives the electric motor 8406, but also the headlights. It can supply power to light-emitting devices such as the Ito 8401 and room lights (not shown). .

[0204] Furthermore, the secondary battery is used for the speedometer, tachometer, and other displays in the 8400 automobile. It can supply power to the device. In addition, the secondary battery is the navigation system of the 8400 automobile. It can supply power to semiconductor devices such as ignition systems.

[0205] The automobile 8500 shown in Figure 19(B) is a secondary battery that the automobile 8500 has a plug-in type It can be charged by receiving power from an external charging facility using methods such as contactless power supply. Figure 19(B) shows the two devices mounted on the automobile 8500, connected to the ground-mounted charging device 8021. The next diagram shows the state in which the battery 8024 is being charged via cable 8022. Therefore, charging methods and connector specifications are subject to the standards of CHAdeMO (registered trademark) and Combo, etc. The method can be carried out as appropriate. The charging device 8021 is installed at a charging station in a commercial facility. It is also fine to use a household power supply. For example, plug-in technology allows for external power supply. The power supply can charge the secondary battery 8024 installed in the 8500 vehicle. Charging is performed by converting AC power through a converter such as an AC / DC converter in the charging device 8021. It can be done by converting to DC power. It also features an AC / DC converter 8025 for charging. In the case of the 8500 model, charging can be performed even when an AC power source is connected.

[0206] 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 doing so. In this contactless power supply method, power transmission equipment is installed in roads or exterior walls. By incorporating this, charging can be performed not only when the vehicle is stopped but also while it is in motion. Furthermore, this contactless power supply... This method may be used to transmit and receive power between vehicles. Furthermore, the exterior of the vehicle Solar panels may be installed to charge the secondary battery when the vehicle is stopped or in motion. Electromagnetic induction or magnetic resonance methods can be used to supply power to it.

[0207] Furthermore, Figure 19(C) shows an example of a two-wheeled vehicle using a secondary battery according to one embodiment of the present invention. Figure 19 The scooter 8600 shown in (C) includes a secondary battery 8602, side mirrors 8601, and turn signals. It is equipped with a light 8603. The secondary battery 8602 supplies electricity to the turn signal light 8603. can.

[0208] Furthermore, the scooter 8600 shown in Figure 19(C) has a secondary battery 860 in the under-seat storage 8604. It can store 2. The secondary battery 8602 can be stored even if the under-seat storage 8604 is small. It can be stored in the under-seat storage compartment 8604. The secondary battery 8602 is removable. When charging, the 8602 secondary battery must be carried indoors, charged, and stored before driving. That's all you need to do.

[0209] According to one aspect of the present invention, the cycle characteristics of the secondary battery are improved, and the capacity of the secondary battery is increased. This makes it possible to make the secondary battery itself smaller and lighter. Making the body smaller and lighter contributes to reducing the vehicle's weight, which in turn improves its driving range. It is possible. Furthermore, the secondary battery installed in the vehicle can also be used as a power source for purposes other than the vehicle itself. In this case, for example, it is possible to avoid using commercial power during peak electricity demand. Therefore, if we can avoid using commercial power during peak electricity demand, we can save energy and It can contribute to reducing carbon dioxide emissions. Also, if the cycle characteristics are good, two Because the next battery can be used for a long period of time, the amount of rare metals used, including cobalt, can be reduced. It is possible.

[0210] This embodiment can be implemented in appropriate combination with other embodiments. [Examples]

[0211] In this embodiment, a secondary battery was fabricated using positive electrode active material particles having different coating layers, and SEM The results of analyzing features using XRD and comparing their properties are shown.

[0212] <Fabrication of positive electrode active material> In this example, cobalt was used as metal element M1 and titanium as metal element M2. Active cathode material of pulls 11 to sample 14, samples 21 to sample 24, and sample 31 Quality was prepared. The preparation method for each sample was as follows:

[0213] Sample 11 Sample 11 was prepared using the sol-gel method on lithium cobalt oxide particles containing magnesium and fluorine. The material was fabricated by first forming a titanium-containing coating layer and then heating it.

[0214] In this embodiment, a pre-synthesized magnesium and fluorine-containing koba is used as the starting material. Lithium phosphate particles were used. Specifically, product name C-20F manufactured by Nippon Chemical Industrial Co., Ltd. was used as the starting material. It was used as a material.

[0215] 2-Propanol is prepared so that the TTIP per unit weight of the positive electrode active material is 0.004 ml / g. TTIP was added and dissolved. TTIP is manufactured by Kishida Chemical Co., Ltd. and has a purity of 99.0% or higher. A reagent was used. This 2-propanol solution of TTIP contains magnesium and fluorine. Lithium cobalt oxide particles were added.

[0216] This mixture of magnesium and lithium cobalt oxide particles containing fluorine is called Mag The mixture was stirred in a Netic stirrer for 70 hours under conditions of 25°C and 90% RH humidity. This causes hydrolysis and polycondensation reactions to occur between water in the atmosphere and TTIP, resulting in magnesium A layer containing titanium was formed on the surface of lithium cobalt oxide particles that also contain fluorine.

[0217] The mixture after the above processing was filtered, and the residue was collected. Kiriyama filter paper was used for filtration. (No. 4) was used.

[0218] The collected residue was dried at 70°C for 3 hours.

[0219] The dried powder was heated. Heating was performed at 800°C (increase of temperature by 200°C per hour), and the holding time was 2 hours. The procedure was performed with an oxygen atmosphere flow rate of 10 L / min.

[0220] The heated powder was cooled. The cooling process took the same amount of time as the heating process, or longer. The material was then sieved. A sieve with a mesh size of 53 μm was used.

[0221] The sieved particles were used as the positive electrode active material for sample 11.

[0222] Sample 11 contains lithium cobalt oxide internally and titanium and magnesium in its surface layer. It was presumed to be a positive electrode active material having a coating layer.

[0223] ≪Sample 12≫ Sample 12, as a comparative example, was prepared by forming a titanium-containing layer, drying it, and then performing the following steps without heating. It was prepared in the same manner as Sample 11, except that heating was not performed.

[0224] Sample 12 has lithium cobalt oxide containing magnesium and fluorine internally, and the table A positive electrode active material having a coating layer containing titanium in its layers, but with no magnesium segregated on the surface. It was inferred that this was the case.

[0225] ≪Sample 13≫ Sample 13 was prepared as a comparative example without forming a titanium-containing layer. Aside from the parts that were not formed, the sample was prepared in the same manner as Sample 11.

[0226] Sample 13 has lithium cobalt oxide inside and a coating layer containing magnesium on the surface. It was inferred that the positive electrode active material possesses [certain properties] but does not contain titanium.

[0227] Sample 14 Sample 14, as a comparative example, did not form a titanium-containing layer and was not heated. The C-20F manufactured by Nippon Chemical Industrial Co., Ltd. was used as is.

[0228] Sample 14 is lithium cobalt oxide containing magnesium and fluorine, but the coating layer It is a positive electrode active material that does not possess [a specific characteristic].

[0229] ≪Sample 21≫ Sample 21 was obtained by sol-gel method using lithium cobalt oxide particles containing magnesium and fluorine. The material was fabricated by first forming a titanium-containing coating layer and then heating it.

[0230] The TTIP per positive electrode active material was set to 0.01 ml / g, and the heating atmosphere was dry air. The rest were prepared in the same way as Sample 11.

[0231] Sample 21 contains lithium cobalt oxide internally and titanium and magnesium in its surface layer. It was presumed to be a positive electrode active material having a coating layer.

[0232] Sample 22 Sample 22 was prepared as a comparative example without forming a titanium-containing layer. Aside from the parts that were not formed, the sample was prepared in the same way as Sample 21.

[0233] Sample 22 has lithium cobalt oxide inside and a coating layer containing magnesium on the surface. It was inferred that the positive electrode active material possesses [certain properties] but does not contain titanium.

[0234] ≪Sample 23≫ Sample 23, as a comparative example, consists of lithium cobalt oxide particles without magnesium, with titanium added. It was prepared by forming a layer containing n and then heating it.

[0235] Lithium cobalt oxide particles were manufactured by Nippon Chemical Industrial Co., Ltd. (product name: C-10N). This is X Lithium cobalt oxide, in which magnesium is not detected by PS, and fluorine is detected at approximately 1 atomic percent. It is a particle.

[0236] Aside from using C-10N as the starting material, it was prepared in the same manner as Sample 21.

[0237] Sample 23 has lithium cobalt oxide internally and a titanium-containing coating layer on its surface. However, it was inferred that the positive electrode active material did not have magnesium segregated on its surface.

[0238] Sample 24 Sample 24, as a comparative example, consists of lithium cobalt oxide particles without magnesium, with titanium added. No layer containing was formed, and no heating was performed. Specifically, C-10N manufactured by Nippon Chemical Industrial Co., Ltd. was used. I used it as is.

[0239] Sample 24 is lithium cobalt oxide without a coating layer.

[0240] ≪Sample 31≫ Sample 31 was prepared using the sol-gel method on lithium cobalt oxide particles containing magnesium and fluorine. The material was fabricated by first forming a titanium-containing coating layer and then heating it.

[0241] The sample was prepared in the same manner as Sample 11, except that the TTIP per positive electrode active material was set to 0.01 ml / g. did.

[0242] Sample 31 contains lithium cobalt oxide internally and titanium and magnesium in its surface layer. It was presumed to be a positive electrode active material having a coating layer.

[0243] Preparation of Samples 11-14, Samples 21-24, and Sample 31 The conditions are shown in Table 1. The analyses performed on each sample, described later, are also shown.

[0244] [Table 1]

[0245] <sem> The results of observations of samples 11 and 14 using SEM are shown in Figure 3. That's right. By forming a layer containing titanium and heating it, cracks and a small surface area can be reduced. It has become clear that a relatively smooth positive electrode active material 100 can be fabricated.

[0246] <xrd> For samples 11 to 14, the size of crystallites inside the positive electrode active material particles was determined using XR. The analysis was performed using D. The results are shown in Table 2.

[0247] [Table 2]

[0248] As shown in Table 2, sample 11, which was coated with a titanium layer and heated, was compared to other samples. Compared to the previous case, a tendency for larger crystallites was observed. The tendency for larger crystallites was observed on the crystal plane. Therefore, differences were observed, particularly in the (003) plane.

[0249] The more cracks there are, the lower the crystallinity, resulting in smaller crystallite sizes. As crystallinity increases, the crystallite size is thought to become larger.

[0250] Furthermore, it is presumed that defects such as cracks are more likely to occur along the (003) plane, etc. Figure 20 is a model diagram of the crystal structure of lithium cobalt oxide (LiCoO2). The direction perpendicular to the plane is the a-axis, the shorter side of the rectangle in the diagram is the b-axis, and the longer side of the rectangle is the c-axis. Yes. In the figure, the (003) plane is shown by a dotted line. As shown in Figure 20, the (003) plane has a layered structure. It exhibits the following properties. In lithium cobaltate, the bond between lithium and oxygen is between cobalt and oxygen. The bond is weaker than that. Therefore, defects such as cracks occur parallel to the (003) plane. It is suspected that this area is prone to stiffness.

[0251] As in this embodiment, by coating with a titanium layer and heating, the (003) surface and other factors It was suspected that defects, including cracks, had been repaired.

[0252] <Cycle characteristics at 25°C> Using the positive electrode active materials of Samples 21 to 24, a CR2032 type (20mm diameter) was created. We fabricated a coin-shaped secondary battery (3.2 mm in height) and evaluated its cycle characteristics.

[0253] The positive electrode contains the positive electrode active material (LCO) from samples 21 to 24 and acetylene black. (AB) and polyvinylidene fluoride (PVDF) are in the ratio LCO:AB:PVDF=95:2. A slurry mixed in a 5:2.5 (by weight) ratio is used, coated onto an aluminum foil current collector. N-methyl-2-pyrrolidone (NMP) was used as the solvent.

[0254] Lithium metal was used for the counter electrode.

[0255] The electrolyte in the electrolyte solution is 1 mol / L lithium hexafluoride phosphate (LiPF6). The electrolyte contains ethylene carbonate (EC) and diethyl carbonate (DEC). A mixture of C:DEC = 3:7 (volume ratio) is combined with vinylene carbonate (VC) at a ratio of 2 A mixture containing a weight percentage of the additive was used.

[0256] The positive electrode and negative electrode cans were made of stainless steel (SUS).

[0257] The measurement temperature for the cycle performance test was set to 25°C. Charging was performed using CCCV, first by the weight of the active material. The test was performed with a constant current of 68.5 mA / g and an upper voltage limit of 4.6 V, and then the current density was reduced to 1.4 Constant voltage charging was performed until the current density reached mA / g. Discharge was performed using CC, with a current density of 6 per unit weight of active material. The test was performed with a constant current of 8.5 mA / g and a lower voltage limit of 2.5 V.

[0258] The CCCV charging and CC charging conditions in this embodiment are the same as those described in Embodiment 2. The voltages may differ from those exemplified in the explanations of CV charging and CC discharging, but the voltages are different. The charging and discharging methods are the same. By charging with a high voltage, high capacity It can be used as a rechargeable battery.

[0259] Figure 21 shows the 4.6V charging of secondary batteries using the positive electrode active materials of samples 21 to 24. The graph shows the discharge capacity retention rate and the number of charge / discharge cycles at a given time. The discharge capacity retention rate is calculated from the first discharge. The calculation was performed assuming a capacity of 100%.

[0260] As is clear from Figure 21, these are lithium cobalt oxide particles containing magnesium and fluorine. Sample 22, compared to Sample 24 which lacks a coating layer, forms only a coating layer containing titanium. Compared to sample 23, it showed good cycle characteristics. This is because heating causes magnesium This is thought to be due to the segregation of um onto the surface layer of lithium cobalt oxide particles.

[0261] Furthermore, lithium cobalt oxide particles containing magnesium and fluorine are coated with a titanium-containing layer. The resulting cathode active material, sample 21, exhibited extremely good cycle characteristics. Sample 22, in which magnesium segregated to the surface layer, and a coating layer containing titanium were formed. The characteristics were superior to those of sample 23.

[0262] In the cycle characteristic measurement, the discharge capacity retention rate after 10 cycles was 99%. The discharge capacity retention rate after 30 cycles was 97%.

[0263] Thus, by providing a coating layer having titanium and magnesium, Better cycle than having only a coating layer or only a coating layer containing magnesium. It became clear that certain characteristics could be obtained.

[0264] <Initial characteristics, rate characteristics, and cycle characteristics at 45°C> A secondary battery was fabricated using the positive electrode active material of Sample 31, and its initial characteristics and cycle characteristics were evaluated. It was worth it.

[0265] The positive electrode contains the positive electrode active material (LCO) of sample 31, acetylene black (AB), and Refynylidene fluoride (PVDF) (manufactured by Solvay, product name: GE51305) is used by LCO: A slurry mixed with AB:PVDF = 95:3:2 (by weight) is used as a current collector for aluminum foil. A coated material was used. N-methyl-2-pyrrolidone (NMP) was used as the solvent. The amount of current loaded onto the electrode current collector is approximately 8.5 mg / cm³. 2 This was done. The rest was done in the same way as samples 21-24. It was made.

[0266] First, regarding the secondary battery using the positive electrode active material of Sample 31, the initial characteristics and rate characteristics were... It was measured.

[0267] The initial charge / discharge characteristics were measured using CC / CV, 0.2C, 4.55V, and 0.05C cutoff. The procedure was performed with the circuit off. Discharge was performed with CC, 0.2C, and a 3.0V cutoff. Note that 1C = 160 The measurement was performed at a temperature of 25°C, with a unit of mAh / g.

[0268] The rate capacity was measured after the initial charge and discharge. The discharge rate was varied, and all other factors were measured during the initial charge and discharge. Under the same conditions as discharge, 0.2C charge / 0.2C discharge, 0.2C charge / 0.5C discharge, 0.2 Measurements were taken in the following order: 1.0C charge / 1.0C discharge, and 0.2C charge / 2.0C discharge. The measurement temperature was 25°C. It was set to °C.

[0269] The results of the initial characteristics and rate capacity measurements are shown in Table 3 and Figure 22.

[0270] [Table 3]

[0271] Figure 22(A) is a graph of the rate capacity from Table 1. Figure 22(B) is a graph of Table 3. This graph shows the rate capacity normalized to a capacity of 0.2C.

[0272] [Cycle Characteristics] In terms of cycle characteristics, charging is CC / CV, 1.0C, 4.55V, 0.05C cutoff. Discharge was performed with CC, 1.0C, and a 3.0V cutoff. The measurement temperature was 45°C. Figure 23 shows a graph of the cycle characteristics in terms of discharge capacity retention rate.

[0273] In the cycle characteristic measurement, the discharge capacity retention rate was 100% after 10 cycles. The discharge capacity retention rate at 30 cycles was 98%. Also, the discharge at 100 cycles... The capacity retention rate was 79%.

[0274] Furthermore, the specific surface area of ​​the positive electrode active material of sample 31 was measured to be 0.13 m². 2 / g Ta.

[0275] Furthermore, the particle size distribution of the positive electrode active material of sample 31 was measured, and the average particle size was 25.5 μm. The 10%D particle size was 13.5 μm, the 50%D particle size was 23.9 μm, and the 90%D particle size was 56.4 μm.

[0276] As described above, the positive electrode active material particles of Sample 31, which is one aspect of the present invention, exhibit extremely good initial properties. It was revealed that the charge-discharge capacity, rate capacity, and cycle characteristics are all evident.

[0277] From the above results, the positive electrode active material particles, which are one aspect of the present invention, are extremely effective when used in a secondary battery. It became clear that good cycle characteristics could be obtained. [Explanation of Symbols]

[0278] 100 active material particles 105 Crack 110 Active material particles 111 particles 150 dotted lines 170 Isopropanol 171 TTIP 172 TiOx sol 173 Dry Gel 200 Active material layer 201 Graphene Compounds 300 Secondary battery 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 310 Separator< / xrd> < / sem>

Claims

1. A lithium-ion secondary battery comprising a positive electrode having active material particles, a negative electrode, and a polymer gel electrolyte, The active material particles include lithium, cobalt, titanium, magnesium, and oxygen. The active material particles have multiple crystallites, The active material particle has a first region located inside and a second region located outside the first region. The second region contains more titanium than the first region. The second region contains more magnesium than the first region. The crystallite size of the active material particles, as measured by X-ray diffraction analysis, is 0.5 μm or larger. Lithium-ion rechargeable battery.

2. A lithium-ion secondary battery comprising a positive electrode having active material particles, a negative electrode, and a solid electrolyte, The active material particles include lithium, cobalt, titanium, magnesium, and oxygen. The active material particles have multiple crystallites, The active material particle has a first region located inside and a second region located outside the first region. The second region contains more titanium than the first region. The second region contains more magnesium than the first region. The crystallite size of the active material particles, as measured by X-ray diffraction analysis, is 0.5 μm or larger. Lithium-ion rechargeable battery.

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