Active material, electrode, secondary battery, battery pack, and vehicle

Abstract

This invention provides active materials, electrodes, secondary batteries, battery packs, and vehicles for secondary batteries that achieve excellent fast charge / discharge performance and cycle life. It provides an active material comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure containing an octahedral structure composed of oxygen and metal elements, and formed by the common vertices of the octahedral structure. The composite oxide is in the form of the general formula Li. a M b NbMo c O d M is selected from any one or more of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, where 0 ≤ a ≤ b + 2 + 3c, 0 ≤ b ≤ 1.5, 0 ≤ c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.50. In the micro Raman spectrophotometer of the composite oxide at an excitation wavelength of 532 nm, the value is located at 640 ± 10 cm⁻¹. ‑1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. ‑1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. ‑1 above.

Description

Technical Field

[0001] Embodiments of the present invention relate to active materials, electrodes, secondary batteries, battery packs, and vehicles. Background Technology

[0002] In recent years, research and development of secondary batteries, such as lithium-ion batteries and non-aqueous electrolyte batteries, have been actively pursued as high-energy-density batteries. Secondary batteries are expected to serve as power sources for vehicles such as hybrid electric vehicles and electric cars, or as uninterrupted power supplies for mobile phone base stations. Therefore, in addition to energy density, secondary batteries are required to possess excellent performance characteristics such as rapid charge / discharge capabilities and long-term reliability.

[0003] As a common negative electrode in lithium-ion batteries, carbon-based negative electrodes using carbonaceous materials such as graphite as the active material can be cited. However, batteries using carbon-based negative electrodes are prone to lithium dendrite deposition on the electrodes during repeated rapid charge-discharge cycles, raising concerns about potential overheating and fires due to internal short circuits. Therefore, a new type of battery has been developed that uses a metal composite oxide instead of carbonaceous materials in the negative electrode, thereby increasing the negative electrode's operating potential. For example, spinel-type lithium-titanium composite oxide Li₄Ti₅O₅ is used in the negative electrode. 12 The battery has an average operating potential as high as 1.55V (vs. Li / Li). + Therefore, no Li dendrites precipitate, enabling stable and rapid charge-discharge. Furthermore, because it operates at a potential where reduction side reactions in the electrolyte are less likely to occur, its lifespan is longer compared to batteries using carbon-based anodes. However, the use of Li₄Ti₅O₂ in the anode... 12 For batteries with active materials, the theoretical capacity is as low as 175 mAh / g, which presents a problem of low energy density compared to batteries with carbon-based anodes.

[0004] Therefore, monoclinic niobium titanium oxide TiNb₂O₇ was studied. Its redox potential was used as a reference at 1V (vs. Li / Li). + The active material exhibits a high capacity and has an operating potential near the anode. Therefore, it is expected to achieve a higher volumetric energy density than carbon-based anodes. However, in order to achieve widespread adoption of electric vehicles, the energy density of lithium-ion secondary batteries is expected to be further improved in the future, from the perspective of increasing driving range, and it is hoped that higher-capacity fast-charging batteries will be developed. Summary of the Invention

[0005] The purpose of this embodiment is to provide active materials and electrodes for a secondary battery that achieves excellent fast charge / discharge performance and cycle life performance, a secondary battery and battery pack that achieve excellent fast charge / discharge performance and cycle life performance, and a vehicle equipped with the battery pack.

[0006] According to an embodiment, an active material is provided, comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure, wherein the rhenium oxide-type bulk structure contains an octahedral structure composed of oxygen and a metallic element, and is formed by sharing vertices of the octahedral structure. The composite oxide is in the form of the general formula Li a M b NbMo c O d Indicated. Where M is selected from any one or more of the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, 0≤a≤b+2+3c, 0≤b≤1.5, 0≤c≤0.5, and 2.33≤d / (1+b+c)≤2.50. In the micro Raman spectrophotometer of the composite oxide at an excitation wavelength of 532 nm, it is located at 640±10 cm⁻¹. -1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. -1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. -1 above.

[0007] According to another embodiment, an electrode is provided that comprises the above-described active material.

[0008] According to another embodiment, a secondary battery is provided, which includes a positive electrode, a negative electrode, and an electrolyte. The positive or negative electrode is the electrode described above.

[0009] According to another embodiment, a battery pack is provided which includes the aforementioned secondary battery.

[0010] Furthermore, according to an embodiment, a vehicle is provided which includes the aforementioned battery pack.

[0011] According to the above embodiments, it is possible to provide active materials and electrodes for a secondary battery that achieves excellent fast charge / discharge performance and cycle life performance, a secondary battery and battery pack that achieve excellent fast charge / discharge performance and cycle life performance, and a vehicle equipped with the battery pack. Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an example of the crystal structure that the composite oxide contained in the active material of the embodiment may contain.

[0013] Figure 2 This is a schematic diagram illustrating other examples of the crystal structures that the composite oxide contained in the active material of the embodiment may contain.

[0014] Figure 3This is a cross-sectional view that schematically illustrates an example of a secondary battery implementation.

[0015] Figure 4 It is Figure 3 The cross-sectional view is obtained by magnifying part A of the secondary battery shown.

[0016] Figure 5 This is a partial notch perspective view schematically illustrating other examples of secondary batteries in various embodiments.

[0017] Figure 6 It is Figure 5 The cross-sectional view of part B of the secondary battery shown is magnified.

[0018] Figure 7 This is a perspective view that schematically illustrates an example of a battery pack embodiment.

[0019] Figure 8 This is an exploded perspective view that schematically illustrates an example of a battery pack embodiment.

[0020] Figure 9 It means Figure 8 The diagram shows a block diagram of an example of the electrical circuitry of the battery pack.

[0021] Figure 10 This is a partial perspective view that schematically represents an example of a vehicle according to an embodiment.

[0022] Figure 11 This is a diagram that schematically illustrates an example of a control system for the electrical system in a vehicle according to an embodiment.

[0023] Figure 12 The graphs represent the Raman spectra obtained in Examples 1-3 and Comparative Example 1.

[0024] [Symbol Explanation]

[0025] 1…Electrode assembly, 2…Outer packaging component, 3…Negative electrode, 3a…Negative electrode current collector, 3b…Negative electrode active material containing layer, 4…Separator, 5…Positive electrode, 5a…Positive electrode current collector, 5b…Positive electrode active material containing layer, 6…Negative terminal, 7…Positive terminal, 10…Crystal structure, 10a…Octahedron, 10b…Tetrahedron, 11…Crystal structure, 11a…Octahedron, 11b…Tetrahedron, 18…Metal element, 19…Oxygen element, 2 1…busbar, 22…positive side lead, 23…negative side lead, 24…adhesive tape, 31…container, 32…cap, 33…protective sheet, 34…printed circuit board, 35…wiring, 40…vehicle body, 41…vehicle power supply, 42…electrical control device, 43…external terminal, 44…converter, 45…drive motor, 100…secondary battery, 200…battery pack, 200a…battery pack, 200b… Battery pack, 200c… battery pack, 300… battery pack, 300a… battery pack, 300b… battery pack, 300c… battery pack, 301a… battery monitoring device, 301b… battery monitoring device, 301c… battery monitoring device, 342… positive side connector, 343… negative side connector, 345… thermistor, 346… protection circuit, 342a… wiring, 343a… wiring, 350… for power supply External terminal, 352…positive side terminal, 353…negative side terminal, 348a…positive side wiring, 348b…negative side wiring, 400…vehicle, 411…battery management device, 412…communication bus, 413…positive terminal, 414…negative terminal, 415…switching device, 416…current detection unit, 417…negative input terminal, 418…positive input terminal, L1…connecting wire, L2…connecting wire, W…drive wheel. Detailed Implementation

[0026] To obtain high-capacity materials, materials with high charge compensation during carrier ion (e.g., lithium ion) insertion are preferred. Therefore, as compounds with further high capacity, composite oxides containing a hexavalent element, molybdenum (Mo), can be used, for example. However, as molybdenum-niobium composite oxide materials, no battery materials containing a higher molybdenum content have been reported.

[0027] The embodiments will now be described with reference to the accompanying drawings. It should be noted that in the following description, components performing the same or similar functions will be labeled with the same reference numerals throughout the drawings, and repeated descriptions will be omitted. It should also be noted that the drawings are schematic diagrams to aid in the explanation and understanding of the embodiments; their shapes, dimensions, proportions, etc., may differ from actual devices, but appropriate design changes can be made with reference to the following description and known techniques.

[0028] (First Implementation)

[0029] According to a first embodiment, an active material comprising a composite oxide having a crystal structure is provided. The crystal structure comprises a rhenium oxide-type bulk structure formed by the common vertices of an octahedral structure composed of oxygen and metal elements. The composite oxide is in the form of the general formula Li... a M b NbMo c O d In the general formula, M is at least one selected from the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. The subscripts in the formula satisfy 0 ≤ a ≤ b + 2 + 3c, 0 ≤ b ≤ 1.5, 0 ≤ c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.50, respectively. In the micro Raman spectrophotometer at an excitation wavelength of 532 nm for the composite oxide, the Raman peak originating from the bonds between oxygen and metal elements contained in the above crystal structure is located at 640 ± 10 cm⁻¹. -1 The displacement S1 (cm) of the Raman peak P1 originating from the Mo-O bond within the range -1 ) and at 920±20cm -1 The displacement S2 (cm) of the Raman peak P2 originating from the Nb-O bond within the range -1 The difference between S2 and S1 is 285cm. -1 above.

[0030] Furthermore, the subscript b mentioned above can be in the range of 0 ≤ b ≤ 1.4.

[0031] The active material can be a battery active material. For example, it can be an electrode active material used in the electrodes of secondary batteries such as lithium-ion batteries and non-aqueous electrolyte batteries. More specifically, the active material can be a negative electrode active material used in the negative electrode of a secondary battery.

[0032] By using the above general formula Li a M b NbMo c O d (Element M and its subscripts are as described above; omitted below) indicates a composite oxide with a crystal structure containing the above-described rhenium oxide type, and whose Raman peaks P1 and P2 in the Raman spectrum satisfy the shift difference S2-S1 as an electrode active material, which can achieve excellent fast charge and discharge performance and cycle life performance in a secondary battery.

[0033] <Crystal Structure>

[0034] The composite oxide contained in the active material of the first embodiment corresponds to a portion of an oxide material having a structure of the Wadsley-Roth phase, a crystalline phase found in oxide materials containing niobium. Regarding the Wadsley-Roth phase, it has been reported that the number of oxygen atoms and the number of metal atoms are each set as A for the ratio of oxygen (O) to metal element (M) in the composition. O and A M In 2.33≤A O / A M Crystal structures are taken within the range of ≤2.65. For example, in the case of TiNb2O7, it becomes A. O / A M Crystal structure on the reduction side of 2.33.

[0035] Here, reduction refers to a low proportion of oxygen within the structure. The Wadsley-Roth phase adopts the following crystal structure: a rhenium oxide-type block structure is formed by the shared vertex structure of oxygen-metal octahedrons. The rhenium oxide-type blocks (ReO3 type blocks) are connected along a two-dimensional direction by adding edges or tetrahedrons of the shared octahedrons and sharing vertices. The crystal structure on the reduction side adopts a smaller rhenium oxide-type block structure. Although the rhenium oxide-type crystal structure has many interstitial spaces capable of embedding Li, due to its high symmetry, it is difficult to change the bond length between the metal and oxygen elements to eliminate charge repulsion during Li embedding. Therefore, the rhenium oxide-type crystal structure can be said to be a structure where Li embedding is constrained by charge repulsion during Li embedding. Here, the crystal structure on the reduction side is formed because A O / A M The size of the rhenium oxide-type block decreases, thus reducing the number of oxygen atoms within the structure. As a result, it becomes a crystal structure that can expand in volume due to changes in the bond length between the metal and oxygen elements during Li insertion. Therefore, by incorporating a rhenium oxide-type crystal structure with ample porosity and without constraints on structural changes during Li insertion, a large amount of Li insertion can be achieved.

[0036] Regarding the composite oxide contained in the active material of the first embodiment, like TiNb2O7, by adopting a reduction-side crystal structure, more lithium (Li) can be embedded within the crystal structure, resulting in a crystal structure with large reversible capacity. That is, the crystal structure of the composite oxide belongs to the reduction-side crystal structure of the Wadsley-Roth phase, which is composed of three elements, namely molybdenum and metallic element M, in addition to niobium.

[0037] The general formula Li a M b NbMo c O dA schematic diagram of an example of the crystal structure that the composite oxide may contain is shown in Figure 1 In this example, the number A of oxygen (O) atoms included as a constituent element is given. O The number of atoms A relative to the metallic element M M The ratio becomes A O / A M A crystal structure with a density of 2.50. In Figure 1 In this context, the unit lattice along the

[001] direction, obtained by observing the crystal structure along the c-axis, is represented. The space group label of the crystal structure belongs to I. - 4. The space group is assigned the number 82. The space group referred to here corresponds to the International Tables for Crystallography, specifically Vol. A: Space-group symmetry (Second Online Edition (2016); ISBN: 978-0-470-97423-0, doi: 10.1107 / 97809553602060000114). The space group can also be identified by P4 (space group number 75), I4 (space group number 79), P... - 4 (space group number 81), P42 / n (space group number 86), I4 / m (space group number 87), P4nc (space group number 104), P - 421c (space group number 114), P - 4n2 (space group number 118) and similar to I - 4 (Space Group No. 82) is similar to the classification of simple cubic lattices with fourfold symmetry or fourfold inversion. This classification can sometimes change due to deviations from the stoichiometric ratio caused by adjustments in the composition ratio, or due to strain in the structure caused by the presence of mixing with heterogeneous phases. Crystal structure 10 contains octahedrons 10a and tetrahedrons 10b composed of metallic element 18 and oxygen element 19, respectively. Octahedrons 10a are interconnected by sharing vertices to form rhenium oxide-type blocks (ReO3-type blocks). Regarding the size of the blocks, there are 3 × 3 = 9 octahedrons 10a. These nine rhenium oxide-type blocks form planes along the a-axis and b-axis directions by sharing the edges of octahedrons 10a or the vertices of tetrahedrons 10b. Multiple connections are formed on the c-axis side by sharing the edges of the octahedrons 10a or the vertices of the tetrahedrons 10b, thus forming the crystal structure.

[0038] The general formula Li a M b NbMo c O dSchematic diagrams of other examples of crystal structures that the represented composite oxide may contain are shown in Figure 2 middle. Figure 2 This represents the structure as viewed from the stacking direction of the ReO3 blocks. In crystal structure 11, the ReO3 blocks enclosed by thick lines (e.g., block 15a) differ from those represented by only thin lines (e.g., block 15d) in the planes where the metallic elements 18 are arranged. This example is characterized by the lack of structural periodicity. Blocks of different sizes are connected in a Wadsley-Roth phase arrangement. One side of the block has two elements in the smaller blocks and six elements in the larger blocks. For example, block 15a consists of 3 x 3 octahedrons 11a, block 15b consists of 2 x 3 octahedrons 11a, block 15c consists of 2 x 4 octahedrons 11a, block 15d consists of 2 x 2 octahedrons 11a, block 15e consists of 3 x 6 octahedrons 11a, block 15f consists of 5 x 3 octahedrons 11a, and block 15g consists of 4 x 4 octahedrons 11a. These dimensions can be freely adjusted based on the metal / oxygen ratio according to the mixed state of elements M, Nb, and Mo, without limitation. Most are connected by a total of 17 octahedral edges, but some may also include tetrahedral vertices based on tetrahedrons 11b. Figure 1 Compared to reducing the number of tetrahedrons, replacing the vertex connections of tetrahedrons with edge connections of octahedrons increases the number of shared octahedral edges, thus increasing the octahedral lattice strain. The larger octahedral lattice strain facilitates structural mitigation caused by bond length changes during Li embedding, allowing for increased Li embedding. Furthermore, since the octahedral edge connections are non-periodic, the framework asymmetry is maintained even with increased Li embedding. Therefore, Figure 2 In terms of crystal structure, with Figure 1 The crystal structure further improves the reversible capacity compared to other methods. Therefore, by including [a specific type of crystal structure] in the active material... Figure 2 The crystal structure can also improve the capacity.

[0039] exist Figure 2 In the crystal structure of Li, the metal / oxygen ratio, which varies with the composition ratio, can be adjusted by changing the size of the ReO3 block and the number of connections shared by the octahedral edges or the tetrahedral vertices. Therefore, the oxygen / metal ratio can be changed by altering the composition ratio, as can be achieved in the general formula Li. a M b NbMo c O d The composition can be freely adjusted within its range.

[0040] Molybdenum (Mo) can be incorporated into crystal structures not only in its hexavalent state but also in its tetravalent and pentavalent states. The valence of Mo is determined according to... Figure 1 or Figure 2The charge balance in the crystal structure shown is determined by the amount of mixed metallic elements other than Mo and the amount of oxygen. For hexavalent elements, the theoretical capacity of intercalable Li is increased because the charge compensation during Li intercalation with M elements such as Ti results in a 3-electron reaction. Elements in tetravalent or pentavalent states are configured within the crystal structure to donate electrons to the d-band of Mo. Therefore, by including tetravalent or pentavalent Mo elements, the conductivity can be changed, thus improving battery performance. It is known that the operating potential of the Wadsley-Roth phase containing molybdenum is higher (more expensive). If we compare oxides containing titanium and niobium, for example, the titanium-niobium-molybdenum composite oxide, as one embodiment, has a higher operating potential compared to TiNb₂O₇ due to its crystal structure containing a high concentration of molybdenum. Consequently, since the operating potential falls within a potential region with fewer reduction side reactions in the electrolyte, high lifetime performance can be achieved.

[0041] In the active material, cycle life performance is improved by forming Schottky-type defects. These Schottky-type defects not only result in oxygen loss, but also cause Mo to disappear and form holes in order to adjust the charge balance. During Li insertion, the defective portions within the material readily capture Li due to less charge repulsion. Therefore, some Li remains within the active material during discharge without being extracted. This effect suppresses the decrease in electronic conductivity after Li extraction, thereby maintaining the electronic conduction pathways within the secondary particles and between active material particles during repeated Li extraction and insertion. As a result, the cycle life performance of the electrode is improved.

[0042] Through the aforementioned effects, the electronic conductivity of the active material is increased by the formation of defects, thereby improving battery performance. On the other hand, if there are too many defects, the captured Li will hinder internal diffusion, so the charge and discharge rates cannot be increased indefinitely.

[0043] In the general formula Li a M b NbMo c O d In this context, the subscript d reflects the amount of oxygen vacancies.

[0044] In the active material, the molecular vibrations of the Mo-O bonds are altered by the introduction of defects. Therefore, quantitative evaluation of these defects can be performed using micro-Raman spectrometry. Specifically, in micro-Raman spectrometry using an excitation wavelength of 532 nm for the active material, the shift S1 (cm) of the Raman peak P1 originating from the Mo-O bonds, among the Raman peaks generated by the transition metal-oxygen bonds derived from the crystal structure, is observed. -1The shift S2 (cm) of the Raman peak P2 derived from the Nb-O bond. -1 The difference between S2 and S1 is 285cm. -1 The above. Raman peak P1 represents the peak originating from octahedral bonds containing Mo. The displacement S1 represents the position of the peak P1, at 640±10 cm. -1 Within the range. Raman peak P2 represents the peak originating from the shared Nb-O octahedral bonds at the apex. Displacement S2 represents the position of the peak P2, within 920±20cm. -1 Within the range. Due to the loss of Mo, Raman peak P1 shifts towards the lower energy side. By setting it to have a shift of 285 cm towards the lower energy side compared to Raman peak P2. -1 The active material in the above states can achieve the aforementioned effects. A larger displacement difference S2-S1 indicates a greater number of defects. Considering fast charge / discharge performance, 290 cm⁻¹ is preferred. -1 The following displacement differences are S2-S1. In micro Raman spectroscopy, for example, the method described later is used.

[0045] General formula Li a M b NbMo c O d The composite oxides represented, as metallic elements, may contain not only Nb and Mo, but also elements different from them, such as M. Figure 2 In the case of the structure, the structure can be maintained by changing the oxygen / metal composition ratio due to the change in charge compensation, through changes in the size of the ReO3 type block and the shared octahedral edges and tetrahedral vertices of the connecting parts. The Mo element can be included in the structure by adjusting its valence within the range of 4 to 6. Furthermore, the active material can easily form Schottky-type defects within the structure as described above. Therefore, the degree of freedom in adjusting the charge balance in the structure is high, and the element M can be freely selected. The element M can be selected from at least one of the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, Zr, and Si. In the above general formula, the subscript b can, for example, satisfy 0. <b。

[0046] The aforementioned element M can be included in the crystal structure, for example, as a metallic element constituting the aforementioned tetrahedral or octahedral structures. Furthermore, element M can exist in the active material in a form not included in the crystal structure of the composite oxide.

[0047] For example, vanadium (V) and phosphorus (P) can be included in the crystal structure as pentavalent elements. Titanium (Ti), zirconium (Zr), and silicon (Si) can be included in the structure as tetravalent elements. Iron (Fe), chromium (Cr), aluminum (Al), bismuth (Bi), antimony (Sb), boron (B), arsenic (As), cobalt (Co), manganese (Mn), nickel (Ni), and yttrium (Y) can be included in the crystal structure as trivalent elements. Magnesium (Mg) and calcium (Ca) can be included in the crystal structure as divalent elements. Potassium (K) and sodium (Na) can be included in the crystal structure as monovalent elements. Among these elements, tetravalent elements are preferred because they have a higher charge than elements with valences of trivalent or lower, and can be included in a large number without reducing the oxygen / metal ratio within the structure, thus increasing the Mo ratio within the structure. In particular, titanium (Ti) is the element that can be included in the structure the most, and because its ionic radius is close to that of pentavalent Nb, it is easily included in the structure, making it the most preferred among M elements.

[0048] Tantalum (Ta) can replace Nb as a pentavalent element. Since Ta and Nb are in the same group on the periodic table, they have similar physical and chemical properties. Therefore, even if Nb is replaced with Ta, equivalent battery performance can be obtained.

[0049] Tungsten (W) can substitute for a portion of Mo as a hexavalent element. It is known that Wadsley-Roth phases containing W generally exhibit high rate performance due to the rapid diffusion of Li within the solid. Therefore, the inclusion of W can further enhance the rate performance of active materials.

[0050] <Active Substance Particles>

[0051] The active material in the first embodiment may, for example, take the form of particles. That is, the active material may be composed of a compound with the general formula Li a M b NbMo c O d This refers to the particle composition of a composite oxide containing the aforementioned crystal structure. The active substance can be a single primary particle, a secondary particle formed by the aggregation of multiple primary particles, or a mixture thereof.

[0052] The average primary particle size of the active material is preferably 10 μm or less, more preferably 5 μm or less, and even more preferably 3 μm or less. If the average primary particle size of the active material is small, the diffusion distance of lithium ions within the primary particles is short, thus tending to improve lithium ion diffusivity. Furthermore, if the average primary particle size of the active material is small, the reaction area increases, thus tending to improve the reactivity of the active material with lithium ions and enhance lithium ion intercalation / deintercalation reactions.

[0053] The average secondary particle size of the active material is preferably 1 μm or more and 50 μm or less. By setting the average secondary particle size of the active material within this range, the productivity during electrode manufacturing can be improved, and batteries with good performance can be obtained. This average secondary particle size refers to the particle size in which the volume cumulative value in the particle size distribution determined by a laser diffraction-type particle size distribution measuring device is 50%.

[0054] The preferred BET specific surface area of ​​the active material is 3.0 m². 2 / g or more and 120m 2 / g or less, preferably 4.0m 2 / g or more and 110m 2 / g or less. Using an active material with a high specific surface area can improve the discharge rate performance of the battery. Furthermore, using an active material with a low specific surface area can improve the battery life performance. In the electrode manufacturing process described later in the second embodiment, the coatability of the slurry containing the active material can be improved.

[0055] BET specific surface area refers to the specific surface area determined by the nitrogen BET (Brunauer, Emmett and Teller) method. The method for determining specific surface area based on this nitrogen BET method will be described in detail later.

[0056] <Manufacturing Method>

[0057] The active substance of the first embodiment can be manufactured as follows.

[0058] (liquid phase synthesis)

[0059] There are no particular limitations on the manufacture of composite oxides, but they can be synthesized by methods such as solid-state reaction, sol-gel method, and hydrothermal synthesis. As an example, a method for manufacturing titanium-niobium-molybdenum composite oxides (i.e., element M = Ti) using the sol-gel method will be described.

[0060] Titanium compounds, niobium compounds, and molybdenum compounds are used as starting materials. Examples of titanium compounds include titanium tetraisopropoxide, titanium oxysulfate, titanium chloride, titanium ammonium oxalate and its hydrate, titanium hydroxide, and titanium oxide. Examples of niobium compounds include niobium chloride, niobium ammonium oxalate and its hydrate, niobium hydroxide, and niobium oxide. Examples of molybdenum compounds include molybdenum chloride, ammonium molybdate and its hydrate, molybdenum hydroxide, and molybdenum oxide. When element M other than Ti is selected, or when other elements are selected together with Ti, the aforementioned titanium compounds are appropriately substituted or combined with compounds containing the selected element M.

[0061] The starting materials are preferably dissolved in pure water or acid beforehand to prepare a solution. Solventization yields a dry gel with homogeneous mixtures of elements, thus improving reactivity. In cases where the raw materials cannot be dissolved in pure water, acid is used for dissolution.

[0062] Examples of acids used to dissolve the raw materials include citric acid and oxalic acid, with oxalic acid being preferred from a solubility point of view. For example, when using oxalic acid, a concentration of 0.5 M or higher and 1 M or lower is preferred. During dissolution, a temperature of 70°C or higher is preferred to shorten the reaction time.

[0063] Even when the raw materials are difficult to dissolve, a dispersion can still be prepared to advance the reaction. In this case, the average particle size of the raw materials contained in the dispersion is preferably 3 μm or less, more preferably 1 μm. After preparing a solution (or dispersion) of each compound adjusted to the specified composition ratio, the solution is heated and stirred while being neutralized with an ammonia solution to adjust the pH. A gel is obtained by pH adjustment. By setting the pH to 5 or higher and 8 or lower, a homogeneous gel containing each raw material can be formed, thereby obtaining a dry gel with good reactivity during calcination.

[0064] Next, gelation is achieved by heating the gel solution to near its boiling point to evaporate the water. After gelation, the solution is further dried by evaporating the water to obtain a dry gel. During gelation and drying, the total volume of the solution can be concentrated by evaporation to obtain a dry gel. The dry gel obtained by evaporating and concentrating the total volume of the solution is preferably pulverized before firing to reduce the average particle size to 10 μm or less, more preferably 5 μm or less. This reduces the particle size after firing. The obtained dry gel is then fired.

[0065] In the process of evaporating the solvent to gel and obtaining a dried gel, a spray dryer is more preferably used. Spraying forms tiny droplets of the sol solution. Drying in the form of tiny droplets prevents particle agglomeration that occurs during solvent drying, resulting in smaller dried particle sizes and a reduction in coarse particles. This improves the homogeneity of the reaction during precursor calcination and also suppresses particle agglomeration during calcination. The drying temperature during spray drying is preferably 100°C or higher and 200°C or lower.

[0066] During the firing of the dried gel, a temporary firing is performed at a temperature between 200°C and 500°C for a firing time between 1 and 10 hours. This allows excess organic components to be burned off, thus improving the reactivity during the formal firing.

[0067] The preferred firing temperature is between 700°C and 900°C, and the firing time is between 1 hour and 10 hours. Firing within this temperature range allows for the acquisition of the target phase and the appropriate introduction of the aforementioned defects. Higher firing temperatures tend to result in a greater amount of defects.

[0068] The calcined powder can sometimes have a high average particle size by forming aggregates. In this case, it is preferable to adjust the specified average particle size by pulverizing.

[0069] The powder produced after mechanical pulverization may sometimes have an amorphous surface. In this case, when used as an active material for batteries, it can generate overvoltages during Li insertion and extraction, which may increase side reactions. Therefore, it is preferable to perform a second annealing treatment. The annealing temperature is below the formal firing temperature, preferably set to 500°C or higher and 800°C or lower.

[0070] <Various Measurement Methods>

[0071] The following describes the methods for determining active substances. Specifically, it explains the identification of complex oxides, the determination of the average particle size of active substance particles, and the determination of the specific surface area of ​​active substances.

[0072] When using the active material contained in the battery electrodes as a sample, the sample is pretreated according to the following method to prepare the test sample. First, the battery is set to a fully discharged state. Next, the battery is disassembled in a glove box under an argon atmosphere, and the electrodes are removed. Then, the removed electrodes are washed with a solvent such as ethyl methyl carbonate. Further processing is performed for each test to prepare a sample of suitable morphology.

[0073] (Confirmation of the composite oxide)

[0074] The active material comprises a crystal structure having the above-described shape and in the form of the general formula Li. a M b NbMo c O dThe identification of the complex oxide can be performed by combining wide-angle X-ray diffraction (XRD), high-angle annular dark-field (HAADF) analysis, inductively coupled plasma (ICP) luminescence analysis, and inert gas dissolution-infrared absorption spectrometry. The crystal structure can be determined using XRD and HAADF, while the elemental composition can be determined using ICP luminescence analysis and inert gas dissolution-infrared absorption spectrometry. The valence of elements can be determined, for example, using characteristic X-ray photoelectron spectrophotometry (XPS).

[0075] XRD measurements are performed as follows. First, the active material particles are thoroughly pulverized to obtain a powder sample. The average particle size of the powder sample is preferably set to be less than 20 μm. This average particle size can be determined using a laser diffraction particle size distribution measuring device.

[0076] Next, the powdered sample is filled into the retainer portion of the glass sample plate to make its surface flat. For example, a sample plate with a retainer portion depth of 0.2 mm can be used as the glass sample plate.

[0077] Next, the glass sample plate was placed in a powder X-ray diffraction apparatus, and the XRD spectrum was measured using Cu-Kα rays. Specific measurement conditions were set as follows:

[0078] X-ray diffraction equipment: SmartLab manufactured by Rigaku Corporation

[0079] X-ray source: CuKα rays

[0080] Output power: 40kV, 200mA

[0081] Packaging Test Name: General Test (Centralized Method)

[0082] Incident parallel slit opening angle: 5°

[0083] Incident length limits slit length: 10mm

[0084] PSA level under light: None

[0085] Parallel slit opening angle for light reception: 5°

[0086] Monochromatic method: Kβ filter method

[0087] Measurement mode: Continuous

[0088] Entrance slit width: 0.5°

[0089] Light-receiving slit width: 20mm

[0090] Measurement range (2θ): 5–70°

[0091] Sampling amplitude (2θ): 0.01°

[0092] Scanning speed: 1°~20° / minute.

[0093] This process yields the XRD spectrum of the active substance. In this XRD spectrum, the horizontal axis represents the incident angle (2θ), and the vertical axis represents the diffraction intensity (cps). The scan rate can be adjusted within a range where the count of the main peak in the XRD spectrum is between 50,000 and 150,000.

[0094] When the active material contained in the battery electrode is used as a sample, the washed electrode obtained after the above pretreatment is cut into an area approximately the same as the area of ​​the holder of the glass sample plate, and used as a test sample.

[0095] Next, the obtained test sample is directly attached to a glass holder for XRD measurement. XRD is used to measure materials other than the active material contained in the electrode, such as current collectors, conductive agents, and adhesives, to obtain their XRD patterns. Then, in cases where peaks from the active material overlap with peaks from other materials in the test sample, the peaks from the non-active material are separated. This process is repeated to obtain the XRD spectrum related to the active material.

[0096] To further rigorously confirm whether the crystal structure contained in the measured sample belongs to the above-mentioned category. Figure 1 The tetragonal crystal structure was determined using the Rietveld method. As an analytical procedure, for example using RIETAN-FP, the reliability factor R was determined. wp The value is confirmed to be at least 20% or less, more preferably 15% or less, for identification. At this time, the presence of peaks containing impurities can sometimes degrade the accuracy of the analysis if they overlap with the phase being analyzed. In such cases, for regions where peaks clearly overlap with the source of impurities, it is preferable to perform analysis outside the analytical range. However, the analysis is not limited to cases where the sample contains materials other than the active substance of the first embodiment, cases where the sample has significantly high orientation, or cases where coarse particles are mixed in, as the intensity ratio changes. The structure is identified by confirming that the positions and relative intensities of all peaks belonging to the crystal structure are consistent. Furthermore, if the spectral intensity is low and the background intensity is low, sometimes R... wpAs the value decreases, the reliability factor becomes meaningless in absolute terms, but meaningful for relatively judging the goodness of fit under certain measurement conditions.

[0097] The analytical method using RIETAN-FP is explained in detail, for example, in Chapter 9, "Let's take a look at using RIETAN-FP," of the first edition of the non-patent literature "Practical Application of Powder X-ray Analysis" (2002), edited by Izumi Nakai and Fujio Izumi, published by the Japan Society for Analytical Chemistry X-ray Analysis Research Conference (Asakura Shoten).

[0098] It should be noted that RIETAN-FP is the Rietveld parser that is being released free of charge (as of August 2022) on the webpage (http: / / fujioizumi.verse.jp / ) of its developer on the Internet.

[0099] Figure 2 Because its structure lacks periodicity, it is difficult to analyze using XRD. To determine... Figure 2 The structure is best observed directly, focusing on the fine details. This observation can be performed using a scanning transmission electron microscope (STEM) employing the high-angle annular dark-field (HAADF) method. From the viewpoint of improving measurement resolution, spherical aberration correction is preferred. By obtaining atomic images (10 nm × 10 nm) perpendicular to the ReO3 block, the positional relationships of the metallic elements constituting the ReO3 block can be confirmed, thus revealing its structure.

[0100] The content of each element in the active material particles contained in the sample can be determined by ICP-luminescence analysis for metallic elements. For oxygen (O), methods such as inert gas dissolution-infrared absorption spectroscopy can be used for quantification, but precise quantification is difficult.

[0101] For the active material particles contained in the electrode, after the pretreatment described above, the following further treatment is performed. The active material-containing component (e.g., the active material-containing layer described in the second embodiment) is peeled off from the washed electrode, for example, from the current collector of the electrode. The peeled portion is then briefly heated in the atmosphere (approximately 1 hour at 500°C) to burn off unwanted components such as binder and carbon. Afterwards, the content of each element can be quantified by performing ICP-luminescence analysis or similar methods.

[0102] The determination of the valence of metallic elements contained in composite oxides using XPS can be performed as follows. For the X-rays used in the determination, hard X-rays are preferred from the perspective of deep detection depth and the ability to measure states closer to the substrate. The spectroscopic method using hard X-rays is also known as HAXPES. The valence can be determined by identifying the positions of the bond energies in the narrow spectrum of each element. For example, regarding Ti, at 459.0 ± 0.4 eV, Ti2p-derived elements were observed. 3 / 2 The peak of the tetravalent form of Mo was observed at 232.2 ± 0.4 eV. 5 / 2 The peak of the hexavalent Nb was observed at 207.5 ± 0.4 eV. 5 / 2 The peak of the 5-valence element. In the case of elements with lower valences, this can be identified by detecting a peak at a lower energy position than the previous valence. In particular, the element Mo may contain valences below 5.

[0103] Sample determination is performed non-destructively, without changing the valence of elements. Therefore, for the determination of complex oxides contained in the electrode, the electrode is used as the sample without material extraction. Care is taken to prevent the charging during sample determination from affecting the peak position. To eliminate peak shifts caused by charging, it is preferable to measure the electrode in a fully discharged state. When the electrode contains a conductive agent, charging can be reduced. Prolonged X-ray irradiation can damage the sample and cause changes in element valence, so care must be taken. Furthermore, when materials with different structures are mixed, peak shifts may occur due to changes in the bonding state, so care must be taken not to confuse this with changes in valence. When elements with different valences are mixed, i.e., when the spectra of multiple peaks are mixed, the spectra are separated by least-squares fitting, and the mixing ratio can be estimated from the area ratio of the separated peaks.

[0104] It should be noted that the general formula Li a M b NbMo c O d The proportion of Li indicated by the subscript 'a' varies depending on the state of charge of the electrode using the composite oxide in the active material. For example, in the case of composite oxides contained in the negative electrode, the subscript 'a' increases as Li intercalates during battery charging and decreases as Li deintercalates during discharge.

[0105] (Raman spectrophotometry)

[0106] As a method for quantitatively evaluating the crystallinity of complex oxides contained in active substances, a micro Raman spectroscopy apparatus can be used. For example, a LabRAM HREvolution fabricated by Horiba Corporation can be used as a micro Raman spectroscopy apparatus. A wavelength of 532 nm is used as the measurement light source. Measurement conditions are selected according to the ratio of peak height (Signal = S) to noise (Noise = N) in the spectrum (S / N ratio) and the principle that fluorescence scattering intensity does not affect the calculation of the measurement intensity. Measurement conditions can be set, for example, as follows: slit size 25 μm, laser intensity 25%, objective lens 100x, grating 1800 gr / mm, exposure time 10 s, and 5 exposures.

[0107] The intensity is calculated by fitting the measured spectrum. Measurement software such as LabSpec6 is used, and preferably, after baseline correction, the Raman shift (cm) of the peak is calculated by least-squares fitting using the Gaussian-Lorentz function. -1 ).

[0108] Raman spectroscopy measurements can be performed, for example, by following the steps described below.

[0109] If the active material is in powder form, it can be evaluated directly. However, when evaluating the active material for use in a battery, the above pretreatment is performed until the electrode is washed, the active material is peeled off from the washed electrode, and a sample is collected.

[0110] The collected sample was used for Raman spectrophotometry, for example, under the conditions described above.

[0111] During the measurement, a standard Si sample is used, and the intensity and Raman shift are corrected according to the apparatus's recommended method before the measurement is performed. In the case of powder measurement, the powder is placed on a sliding glass plate before measurement. For easier focus alignment, it is preferable to flatten the plate in a manner that minimizes unevenness before measurement. When measuring powders containing binders and conductive agents in the electrode, the presence and peak positions of other components in the electrode assembly, such as the conductive agent and binder, are determined. In cases of overlap, peaks related to components other than the active material are separated.

[0112] (Determination of average particle size)

[0113] The average primary particle size of the active material can be determined by observation using a scanning electron microscope (SEM). Specifically, the average primary particle size observed using SEM can be calculated using the following method.

[0114] First, in the first-order particles of the SEM image obtained through SEM observation, the lengths of the longest and shortest axes are measured, and their summed average is set as the first-order particle size. This first-order particle size is then measured using arbitrarily selected 100 particles, and their average is set as the average first-order particle size.

[0115] The average secondary particle size of the active material can be determined by measuring the particle size distribution using a laser diffraction-based particle size distribution measuring device. As the sample for this particle size distribution measurement, a dispersion obtained by diluting the active material with N-methyl-2-pyrrolidone at a concentration of 0.1% to 1% by mass is used. The particle size at which the volume cumulative value in the obtained particle size distribution is 50% is set as the average secondary particle size.

[0116] (Determination of BET specific surface area)

[0117] The BET specific surface area of ​​active material particles can be determined using the following method.

[0118] First, 4g of the active material is collected as a sample. Next, the evaluation battery of the measuring device is degassed by vacuum drying at a temperature above 100°C for 15 hours. A 1 / 2-inch battery can be used as an evaluation battery. Next, the sample is placed in the measuring device. A Shimadzu TriStarII 3020 can be used as an measuring device. Next, in nitrogen gas at 77K (the boiling point of nitrogen), the nitrogen adsorption amount (mL / g) of the sample is measured at each pressure P while the nitrogen pressure P (mmHg) is slowly increased. Next, the value obtained by dividing the pressure P (mmHg) by the saturated vapor pressure P0 (mmHg) of nitrogen is set as the relative pressure P / P0. An adsorption isotherm is obtained by plotting the nitrogen adsorption amount relative to each relative pressure P / P0. Next, a BET plot is calculated from this nitrogen adsorption isotherm and the BET formula, and the specific surface area is obtained using this BET plot. It should be noted that the BET plot is calculated using the BET multi-point method.

[0119] The active material of the first embodiment comprises a crystal structure having a bulk structure containing rhenium oxide, and a general formula Li a M b NbMo c O dThe composite oxides are represented by this formula. The rhenium oxide-type bulk structures are each formed by the shared vertices of an octahedral structure composed of oxygen and metallic elements. In the above general formula, M is selected from any one or more of the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. The subscripts a, b, c, and d are numbers satisfying 0 ≤ a ≤ b + 2 + 3c, 0 ≤ b ≤ 1.5, 0 ≤ c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.50. In the micro Raman spectrophotometer at an excitation wavelength of 532 nm for the composite oxides, there is a 285 cm⁻¹ difference between the Raman shift S1 of the Raman peak P1 originating from the Mo-O bond and the Raman shift S2 of the Raman peak P2 originating from the Nb-O bond. -1 The above-mentioned differences are addressed. Electrodes using the aforementioned composite oxide as the electrode active material exhibit excellent fast charge / discharge performance and cycle life. Furthermore, secondary batteries and battery packs using the aforementioned composite oxide as the electrode active material exhibit excellent fast charge / discharge performance and cycle life. In other words, the active material exhibits excellent fast charge / discharge performance and cycle life.

[0120] (Second Implementation)

[0121] According to a second embodiment, an electrode is provided.

[0122] The electrode of the second embodiment includes the active material of the first embodiment. This electrode can be a battery electrode that includes the active material of the first embodiment as a battery active material. For example, the electrode used as a battery electrode can be a negative electrode containing the active material of the first embodiment as a negative electrode active material. Alternatively, the electrode can be a positive electrode containing the active material of the first embodiment as a positive electrode active material.

[0123] The electrode may comprise a current collector and an active material containing layer. The active material containing layer may be formed on one or both sides of the current collector. The active material containing layer may comprise an active material and any conductive agent and binder.

[0124] The active substance containing layer may contain only the active substance of the first embodiment, or it may contain two or more active substances of the first embodiment. Furthermore, it may contain a mixture of one or more active substances of the first embodiment with one or more other active substances. The content ratio of the active substance of the first embodiment relative to the total mass of the active substance of the first embodiment and other active substances is preferably 10% by mass or more and 100% by mass or less.

[0125] For example, when the active material of the first embodiment is included as the negative electrode active material, other examples of active materials include lithium titanate (e.g., Li) having an orthorhombic manganese oxide structure. 2+x Ti3O7, 0≤x≤3), lithium titanate with spinel structure (e.g., Li) 4+x Ti5O 12 0≤x≤3), titanium dioxide (TiO2), anatase titanium dioxide, rutile titanium dioxide, niobium pentoxide (Nb2O5), manganese barite titanium composite oxide, orthorhombic titanium composite oxide and monoclinic niobium titanium oxide, niobium oxide, niobium titanium oxide, niobium molybdenum composite oxide, niobium tungsten composite oxide.

[0126] As an example of the orthorhombic titanium-containing composite oxides mentioned above, Li can be cited. 2+e M I 2-f Ti 6-g M II h O 14+σ The compound represented. Wherein, M I It is selected from at least one element in the group consisting of Sr, Ba, Ca, Mg, Na, Cs, Rb, and K. M II The composition consists of at least one element selected from the group consisting of Zr, Sn, V, Nb, Ta, Mo, W, Y, Fe, Co, Cr, Mn, Ni, and Al. The subscripts in the composition formula are 0 ≤ e ≤ 6, 0 ≤ f < 2, 0 ≤ g < 6, 0 ≤ h < 6, and -0.5 ≤ σ ≤ 0.5. As a specific example of an orthorhombic titanium-containing composite oxide, Li can be cited. 2+e Na2Ti6O 14 (0≤e≤6).

[0127] As examples of the aforementioned monoclinic niobium titanium oxides, Li can be cited. x Ti 1-y M1 y Nb 2-z M2 z O 7+δ The compounds referred to herein. M1 is at least one compound selected from the group consisting of Zr, Si, and Sn. M2 is at least one compound selected from the group consisting of V, Ta, and Bi. The subscripts in the composition formula are 0 ≤ x ≤ 5, 0 ≤ y < 1, 0 ≤ z < 2, and -0.3 ≤ δ ≤ 0.3. As a specific example of a monoclinic niobium titanium oxide, Li can be cited. x Nb2TiO7 (0≤x≤5).

[0128] Other examples of monoclinic niobium titanium oxides include Li x Ti1-y M3 y+z Nb 2-z O 7-δ The compound represented is M3, which is selected from at least one compound from the group consisting of Mg, Fe, Ni, Co, W, Ta, and Mo. The subscripts in the formula are 0 ≤ x ≤ 5, 0 ≤ y < 1, 0 ≤ z < 2, and -0.3 ≤ δ ≤ 0.3.

[0129] Conductive agents are used to improve current-collecting performance and suppress contact resistance between the active material and the current collector. Examples of conductive agents include carbonaceous materials such as vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, graphite, carbon nanotubes, and carbon nanofibers. One of these can be used as a conductive agent, or a combination of two or more can be used. Alternatively, instead of using a conductive agent, carbon coating or electronically conductive inorganic material coating can be applied to the surface of the active material particles. Furthermore, by simultaneously using a conductive agent and coating the surface of the active material with carbon or a conductive material, the current-collecting performance of the active material containing the layer can be improved.

[0130] Adhesives are used to fill the gaps between dispersed active materials and to bond the active materials to the current collector. Examples of adhesives include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, styrene-butadiene rubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these can be used as an adhesive, or a combination of two or more can be used.

[0131] The proportions of the active material, conductive agent, and binder in the active material containing layer can be appropriately varied depending on the application of the electrode. For example, when using the electrode as the negative electrode of a secondary battery, it is preferable to combine the active material (negative electrode active material), conductive agent, and binder in proportions of 68% by mass or more and 96% by mass or less, 2% by mass or more and 30% by mass or less, and 2% by mass or more and 30% by mass or less, respectively. By setting the amount of conductive agent to 2% by mass or more, the current-collecting performance of the active material containing layer can be improved. Furthermore, by setting the amount of binder to 2% by mass or more, the adhesion between the active material containing layer and the current collector becomes sufficient, and excellent cycle performance can be expected. On the other hand, setting the conductive agent and binder to 30% by mass or less is preferred in terms of pursuing high capacity.

[0132] When the surface of the active material is covered with carbon or a conductive material, the amount of the covering material can be considered as included in the conductive material content. The amount of carbon or conductive material used for covering is preferably 0.5% by mass or more and 5% by mass or less. A covering amount within this range can improve current collection performance and electrode density.

[0133] The current collector uses a material that is electrochemically stable at the potential for lithium (Li) insertion and extraction into the active material. For example, when the active material is used as the negative electrode active material, the current collector is preferably made of copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing one or more elements selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. The thickness of the current collector is preferably 5 μm or more and 20 μm or less. A current collector with such a thickness achieves a balance between electrode strength and lightweight.

[0134] Furthermore, the current collector can be contained in the portion of its surface where no active material layer has been formed. This portion can function as a current collector tab.

[0135] Electrodes can be fabricated, for example, by the following method. First, a slurry is prepared by suspending an active material, a conductive agent, and a binder in a solvent. This slurry is then coated onto one or both sides of a current collector. Next, the coated slurry is dried to obtain a laminate containing an active material layer and a current collector. This laminate is then pressed. Electrodes are fabricated by operating in this manner.

[0136] Alternatively, the electrode can be fabricated using the following method. First, an active material, a conductive agent, and a binder are mixed to obtain a mixture. Next, this mixture is shaped into granules. Then, by placing these granules onto a current collector, an electrode can be obtained.

[0137] The electrode of the second embodiment contains the active material of the first embodiment. Therefore, the electrode of the second embodiment can achieve a secondary battery with excellent fast charge / discharge performance and cycle life performance.

[0138] (Third Implementation)

[0139] According to a third embodiment, a secondary battery is provided, comprising a negative electrode, a positive electrode, and an electrolyte. This secondary battery includes an electrode of the second embodiment as either the negative or positive electrode. That is, the secondary battery of the third embodiment includes an electrode containing the active material of the first embodiment as a battery active material as a battery electrode. A preferred embodiment of the secondary battery includes an electrode of the second embodiment as the negative electrode. That is, a preferred embodiment of the secondary battery includes an electrode containing the active material of the first embodiment as a battery active material as the negative electrode. The preferred embodiment will be described below.

[0140] The secondary battery may further include a separator disposed between the positive and negative electrodes. The negative electrode, positive electrode, and separator can constitute an electrode assembly. The electrolyte can be retained within the electrode assembly.

[0141] Furthermore, the secondary battery may further include an outer packaging component that houses the electrode assembly and electrolyte.

[0142] Furthermore, the secondary battery may further include a negative terminal electrically connected to the negative electrode and a positive terminal electrically connected to the positive electrode.

[0143] The secondary battery in the third embodiment can be, for example, a lithium secondary battery. Furthermore, the secondary battery includes a non-aqueous electrolyte secondary battery containing a non-aqueous electrolyte.

[0144] The following provides a detailed description of the negative electrode, positive electrode, electrolyte, diaphragm, outer packaging components, negative terminal, and positive terminal.

[0145] 1) Negative electrode

[0146] The negative electrode may include a negative current collector and a negative active material containing layer. The negative current collector and the negative active material containing layer can be the current collector and active material containing layer that can be included in the electrode of the second embodiment, respectively. The negative active material containing layer includes the active material of the first embodiment as the negative active material.

[0147] The parts of the details of the negative electrode that are repeated in the details described in the second embodiment are omitted.

[0148] The density of the negative electrode active material containing the layer (excluding the current collector) is preferably 1.8 g / cm³. 3 Above and 2.8g / cm 3 The following describes the negative electrode with excellent energy density and electrolyte retention within a specific density range for the negative electrode active material layer. A more preferred density for the negative electrode active material layer is 2.1 g / cm³. 3 Above and 2.6g / cm 3 the following.

[0149] The negative electrode can be made, for example, by the same method as the electrode in the second embodiment.

[0150] 2) Positive electrode

[0151] The positive electrode may include a positive current collector and a positive active material containing layer. The positive active material containing layer may be formed on one or both sides of the positive current collector. The positive active material containing layer may include the positive active material and any conductive agent and binder.

[0152] As the positive electrode active material, for example, an oxide or a sulfide can be used. In the positive electrode, as the positive electrode active material, one kind of compound can be included alone, or two or more kinds of compounds can be included in combination. Examples of the oxide and the sulfide include compounds capable of inserting and extracting Li or Li ions.

[0153] Examples of such compounds include manganese dioxide (MnO2), iron oxide, copper oxide, nickel oxide, lithium manganese composite oxide (e.g., Li x Mn2O4 or Li x MnO2; 0 < x ≤ 1), lithium nickel composite oxide (e.g., Li x NiO2; 0 < x ≤ 1), lithium cobalt composite oxide (e.g., Li x CoO2; 0 < x ≤ 1), lithium nickel cobalt composite oxide (e.g., Li x Ni 1-y Co y O2; 0 < x ≤ 1, 0 < y < 1), lithium manganese cobalt composite oxide (e.g., Li x Mn y Co 1-y O2; 0 < x ≤ 1, 0 < y < 1), lithium manganese nickel composite oxide having a spinel structure (e.g., Li x Mn 2-y Ni y O4; 0 < x ≤ 1, 0 < y < 2), lithium phosphorus oxide having an olivine structure (e.g., Li x FePO4; 0 < x ≤ 1, Li x Fe 1-y Mn y PO4; 0 < x ≤ 1, 0 < y ≤ 1, Li x CoPO4; 0 < x ≤ 1), iron sulfate (Fe2(SO4)3), vanadium oxide (e.g., V2O5), and lithium nickel cobalt manganese composite oxide (Li x Ni 1-y-z Co y Mn z O2; 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1).

[0154] Among the above, examples of more preferable compounds as the positive electrode active material include lithium manganese composite oxide having a spinel structure (e.g., Li x Mn2O4; 0 < x ≤ 1), lithium nickel composite oxide (e.g., Li x NiO2; 0 < x ≤ 1), lithium cobalt composite oxide (e.g., Li x CoO2; 0 < x ≤ 1), lithium nickel cobalt composite oxide (e.g., Li x Ni 1-y Co yO2; where 0 < x ≤ 1, 0 < y < 1), lithium manganese nickel composite oxide with a spinel structure (such as Li x Mn 2-y Ni y O4; where 0 < x ≤ 1, 0 < y < 2), lithium manganese cobalt composite oxide (such as Li x Mn y Co 1-y O2; where 0 < x ≤ 1, 0 < y < 1), lithium iron phosphate (such as Li x FePO4; where 0 < x ≤ 1) and lithium nickel cobalt manganese composite oxide (Li x Ni 1-y-z Co y Mn z O2; where 0 < x ≤ 1, 0 < y < 1, 0 < z < 1, y + z < 1). If these compounds are used as the positive electrode active material, the positive electrode potential can be increased.

[0155] When using a room-temperature molten salt as the electrolyte of the battery, it is preferable to use a positive electrode active material containing lithium iron phosphate, Li x VPO4F (0 ≤ x ≤ 1), lithium manganese composite oxide, lithium nickel composite oxide, lithium nickel cobalt composite oxide, or a mixture thereof. These compounds have low reactivity with the room-temperature molten salt, so the cycle life can be increased. Details of the room-temperature molten salt will be described below.

[0156] The primary particle size of the positive electrode active material is preferably 100 nm or more and 1 μm or less. The positive electrode active material with a primary particle size of ≥ 100 nm is easy to operate in industrial production. The positive electrode active material with a primary particle size of ≤ 1 μm can smoothly perform the solid-state diffusion of lithium ions.

[0157] The specific surface area of the positive electrode active material is preferably 0.1 m 2 / g or more and 10 m 2 / g or less. The positive electrode active material with a specific surface area of ≥ 0.1 m 2 / g can fully ensure the insertion / extraction sites of Li ions. The positive electrode active material with a specific surface area of ≤ 10 m 2 / g is easy to operate in industrial production and can ensure good charge-discharge cycle performance.

[0158] Binders are used to fill the gaps between the dispersed positive electrode active materials and to bond the positive electrode active materials to the positive electrode current collector. Examples of binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVdF), fluororubber, polyacrylic acid compounds, imide compounds, carboxymethyl cellulose (CMC), and salts of CMC. One of these can be used as a binder, or a combination of two or more can be used.

[0159] Conductive agents are used to improve current-collecting performance and suppress the contact resistance between the positive electrode active material and the positive electrode current collector. Examples of conductive agents include vapor-grown carbon fiber (VGCF), carbon black such as acetylene black, and carbonaceous materials such as graphite. One of these can be used as a conductive agent, or a combination of two or more can be used. Alternatively, the conductive agent can be omitted.

[0160] In the positive electrode active material containing layer, the positive electrode active material and the binder are preferably mixed in proportions of 80% or more and 98% or less by mass and 2% or more and 20% or less by mass, respectively.

[0161] Sufficient electrode strength can be obtained by setting the amount of binder to 2% by mass or more. Furthermore, the binder functions as an insulator. Therefore, if the amount of binder is set to 20% by mass or less, the amount of insulator contained in the electrode is reduced, thereby reducing internal resistance.

[0162] When a conductive agent is added, the positive electrode active material, binder and conductive agent are preferably mixed in proportions of 77% or more and 95% or less by mass, 2% or more and 20% or less by mass, and 3% or more and 15% or less by mass, respectively.

[0163] The aforementioned effects can be achieved by setting the amount of the conductive agent to 3% by mass or more. Furthermore, by setting the amount of the conductive agent to 15% by mass or less, the proportion of the conductive agent in contact with the electrolyte can be reduced. At this low proportion, electrolyte decomposition can be reduced under high-temperature storage conditions.

[0164] The positive current collector is preferably aluminum foil, or aluminum alloy foil containing one or more elements selected from the group consisting of Mg, Ti, Zn, Ni, Cr, Mn, Fe, Cu and Si.

[0165] The thickness of the aluminum foil or aluminum alloy foil is preferably 5 μm or more and 20 μm or less, more preferably 15 μm or less. The purity of the aluminum foil is preferably 99% by mass or more. The content of transition metals such as iron, copper, nickel, and chromium contained in the aluminum foil or aluminum alloy foil is preferably 1% by mass or less.

[0166] Furthermore, the positive current collector can be included in the portion of its surface where no positive active material layer is formed. This portion can function as a positive current collector tab.

[0167] The positive electrode can be made using a positive electrode active material, for example, by the same method as the electrode in the second embodiment.

[0168] 3) Electrolytes

[0169] As the electrolyte, for example, a liquid non-aqueous electrolyte or a gel-like non-aqueous electrolyte can be used. A liquid non-aqueous electrolyte is prepared by dissolving an electrolyte salt, which is the solute, in an organic solvent. The concentration of the electrolyte salt is preferably 0.5 mol / L or higher and 2.5 mol / L or lower.

[0170] Examples of electrolyte salts include lithium salts such as lithium perchlorate (LiClO4), lithium hexafluoride phosphate (LiPF6), lithium tetrafluoride borate (LiBF4), lithium hexafluoride arsenide (LiAsF6), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethanesulfonyl)imide (LiN(CF3SO2)2), lithium bis(fluorosulfonyl)imide (LiN(SO2F)2; LiFSI), and mixtures thereof. The electrolyte salt is preferably a substance that is difficult to oxidize even at high potentials, with LiPF6 being the most preferred.

[0171] Examples of organic solvents include cyclic carbonates such as propylene carbonate (PC), ethylene carbonate (EC), and vinylene carbonate (VC); chain carbonates such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and methyl ethyl carbonate (MEC); cyclic ethers such as tetrahydrofuran (THF), 2-methyl tetrahydrofuran (2MeTHF), and dioxolane (DOX); chain ethers such as dimethoxyethane (DME) and diethoxyethane (DEE); γ-butyrolactone (GBL); acetonitrile (AN); and sulfolane (SL). These organic solvents can be used alone or as mixed solvents.

[0172] Gel-like nonaqueous electrolytes are prepared by combining liquid nonaqueous electrolytes with polymeric materials. Examples of polymeric materials include polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyethylene oxide (PEO), or mixtures thereof.

[0173] Alternatively, as a non-aqueous electrolyte, in addition to liquid non-aqueous electrolytes and gel non-aqueous electrolytes, room-temperature molten salts (ionic melts) containing lithium ions, polymeric solid electrolytes, and inorganic solid electrolytes can also be used.

[0174] Room-temperature molten salts (ionic melts) refer to compounds that exist as liquids at room temperature (above 15°C and below 25°C) within an organic salt composed of a combination of organic cations and anions. Room-temperature molten salts include those existing as monomers and existing as liquids, those that become liquid by mixing with electrolyte salts, those that become liquid by dissolving in organic solvents, or mixtures thereof. Generally, the melting point of room-temperature molten salts used in secondary batteries is below 25°C. Furthermore, the organic cations typically possess a quaternary ammonium framework.

[0175] Polymer solid electrolytes are prepared by dissolving electrolyte salts in polymer materials and then solidifying them.

[0176] The inorganic solid electrolyte is a solid substance having Li ion conductivity. The so-called having Li ion conductivity means showing a lithium ion conductivity of 1×10 -6 S / cm or more at 25°C. As the inorganic solid electrolyte, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte can be cited. Specific examples of the inorganic solid electrolyte are described below.

[0177] As the oxide-based solid electrolyte, a lithium phosphate solid electrolyte having a NASICON (Sodium (Na) Super Ionic Conductor) type structure and represented by the general formula Li 1+x Mα2(PO4)3 is preferably used. Mα in the above general formula is, for example, one or more selected from the group consisting of titanium (Ti), germanium (Ge), strontium (Sr), zirconium (Zr), tin (Sn), aluminum (Al), and calcium (Ca). The subscript x is in the range of 0≤x≤2.

[0178] Specific examples of the lithium phosphate solid electrolyte having a NASICON type structure include LATP compounds represented by Li 1+ x Al x Ti 2-x (PO4)3 and 0.1≤x≤0.5; compounds represented by Li 1+x Al y Mβ 2-y (PO4)3 where Mβ is one or more selected from the group consisting of Ti, Ge, Sr, Zr, Sn, and Ca and 0≤x≤1 and 0≤y≤1; compounds represented by Li 1+ x Al x Ge 2-x (PO4)3 and 0≤x≤2; and compounds represented by Li 1+x Al x Zr 2-x (PO4)3 and 0≤x≤2; compounds represented by Li 1+x+y Al x Mγ 2-x Si y P 3-y O 12 and Mγ is one or more selected from the group consisting of Ti and Ge and and 0<x≤2, 0≤y<3; compounds represented by Li 1+2x Zr 1-x Ca x (PO4)3 and 0≤x<1.

[0179] In addition to the aforementioned lithium phosphate solid electrolyte, other oxide-based solid electrolytes, such as those based on Li... x PO y N z This refers to amorphous LIPON compounds (e.g., Li) where 2.6 ≤ x ≤ 3.5, 1.9 ≤ y ≤ 3.8, and 0.1 ≤ z ≤ 1.3. 2.9 PO 3.3 N 0.46 ); La with garnet-type structure 5+ xA x La 3-x Mδ2O 12 This indicates a compound in which A is selected from one or more of the group consisting of Ca, Sr, and Ba, and Mδ is selected from one or more of the group consisting of Nb and Ta, with 0 ≤ x ≤ 0.5; Li3Mδ 2-x L2O 12 This indicates that Mδ is a compound selected from one or more species in the group consisting of Nb and Ta, and L may contain Zr and 0 ≤ x ≤ 0.5; with Li 7-3x Al x La3Zr3O 12 Represents compounds in which 0 ≤ x ≤ 0.5; in Li 5+x La3Mδ 2-x Zr x O 12 Mδ represents an LLZ compound selected from the group consisting of Nb and Ta, where 0 ≤ x ≤ 2 (e.g., Li7La3Zr2O). 12 ); and having a perovskite-type structure and with La 2 / 3-x Li x TiO3 represents compounds in which 0.3 ≤ x ≤ 0.7.

[0180] One or more of the above-mentioned compounds may be used as a solid electrolyte. Two or more of the above-mentioned solid electrolytes may also be used.

[0181] Alternatively, instead of non-aqueous electrolytes, liquid aqueous electrolytes or gel-like aqueous electrolytes can be used as the electrolyte. Liquid aqueous electrolytes are prepared by dissolving, for example, the electrolyte salts described above as solutes in an aqueous solvent. Gel-like aqueous electrolytes are prepared by compounding the liquid aqueous electrolyte with the aforementioned polymeric material. As the aqueous solvent, a solution containing water can be used. The solution containing water can be pure water or a mixture of water and an organic solvent.

[0182] 4) Diaphragm

[0183] The diaphragm can be formed, for example, from a porous membrane containing polyethylene (PE), polypropylene (PP), cellulose, or polyvinylidene fluoride (PVdF), or a nonwoven fabric made of synthetic resin. From a safety point of view, porous membranes made of polyethylene or polypropylene are preferred because these porous membranes can melt at a certain temperature and block electric current.

[0184] 5) Outer packaging components

[0185] As outer packaging components, containers made of laminated film or metal containers can be used, for example.

[0186] The thickness of the laminate is, for example, 0.5 mm or less, preferably 0.2 mm or less.

[0187] As a laminated film, a multilayer film comprising multiple resin layers and a metal layer sandwiched between these resin layers is used. The resin layers include, for example, polymeric materials such as polypropylene (PP), polyethylene (PE), nylon, and polyethylene terephthalate (PET). For weight reduction, the metal layer is preferably made of aluminum foil or aluminum alloy foil. The laminated film is sealed by heat-melting bonding and can be shaped into an outer packaging component.

[0188] The thickness of the wall of the metal container is, for example, 1 mm or less, more preferably 0.5 mm or less, and even more preferably 0.2 mm or less.

[0189] Metal containers are made of materials such as aluminum or aluminum alloys. The aluminum alloy preferably contains elements such as magnesium, zinc, and silicon. When the aluminum alloy contains transition metals such as iron, copper, nickel, and chromium, the content of these elements is preferably less than 1% by mass.

[0190] There are no particular limitations on the shape of the outer packaging components. The outer packaging components can be, for example, flat (thin), square, cylindrical, coin-shaped, or button-shaped. The outer packaging components can be appropriately selected according to the battery size and intended use.

[0191] 6) Negative extremes

[0192] The negative terminal can be formed from a material that is electrochemically stable and conductive at the Li insertion / deintercalation potential of the aforementioned negative electrode active material. Specifically, examples of materials for the negative terminal include copper, nickel, stainless steel, or aluminum, or an aluminum alloy containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. Aluminum or an aluminum alloy is preferred as the material for the negative terminal. To reduce the contact resistance with the negative current collector, the negative terminal is preferably formed from the same material as the negative current collector.

[0193] 7) Positive extreme

[0194] The positive terminal can be in a potential range of 3V or higher and 4.5V or lower relative to the redox potential of lithium (vs. Li / Li). + The positive terminal is formed from a material that is electrically stable and conductive. Examples of materials for the positive terminal include aluminum, or aluminum alloys containing at least one element selected from the group consisting of Mg, Ti, Zn, Mn, Fe, Cu, and Si. To reduce the contact resistance with the positive current collector, the positive terminal is preferably formed from the same material as the positive current collector.

[0195] The above describes the embodiment where the electrode of the second embodiment is used as the negative electrode. In the third embodiment of the secondary battery, where the electrode of the second embodiment is used as the positive electrode, the negative electrode can be, for example, the following: At least one electrode selected from lithium metal, lithium metal alloys, graphite, silicon, silicon oxide, tin oxide, silicon, tin, and other alloys can be used as the negative electrode. Materials that do not contain Li in the active material can be used as the negative electrode by pre-doping with Li.

[0196] In the embodiment where the electrode of the second embodiment is used as the positive electrode, the details of the positive electrode are omitted because they are repeated from those described in the second embodiment.

[0197] Next, the secondary battery of the third embodiment will be described in more detail with reference to the accompanying drawings.

[0198] Figure 3 This is a cross-sectional view that roughly represents an example of a secondary battery. Figure 4 It is Figure 3 The cross-sectional view is obtained by magnifying part A of the secondary battery shown.

[0199] Figure 3 and Figure 4 The secondary battery 100 shown has Figure 3 Electrode group 1 shown Figure 3 and Figure 4The bag-shaped outer packaging component 2 and the electrolyte (not shown) are shown. The electrode assembly 1 and the electrolyte are housed within the bag-shaped outer packaging component 2. The electrolyte (not shown) is held within the electrode assembly 1.

[0200] The bag-shaped outer packaging component 2 is made of a laminated film containing two resin layers and a metal layer sandwiched between them.

[0201] like Figure 3 As shown, electrode assembly 1 is a flat, wound electrode assembly. Flat and wound electrode assembly 1 is as follows... Figure 4 As shown, it includes a negative electrode 3, a separator 4, and a positive electrode 5. The separator 4 is sandwiched between the negative electrode 3 and the positive electrode 5.

[0202] The negative electrode 3 includes a negative electrode current collector 3a and a negative electrode active material containing a layer 3b. The outermost portion of the negative electrode 3 located in the wound electrode assembly 1 is as follows: Figure 4 As shown, the negative electrode active material containing layer 3b is formed only on the inner surface side of the negative electrode current collector 3a. In other parts of the negative electrode 3, the negative electrode active material containing layer 3b is formed on both sides of the negative electrode current collector 3a.

[0203] The positive electrode 5 includes a positive current collector 5a and a positive active material containing layer 5b formed on both sides thereon.

[0204] like Figure 3 As shown, the negative terminal 6 and the positive terminal 7 are located near the outer periphery of the wound electrode assembly 1. The negative terminal 6 is connected to the outermost portion of the negative current collector 3a. Similarly, the positive terminal 7 is connected to the outermost portion of the positive current collector 5a. These negative terminals 6 and positive terminals 7 extend to the outside from the opening of the bag-shaped outer packaging member 2. A thermoplastic resin layer is provided on the inner surface of the bag-shaped outer packaging member 2, which is then thermally melted and bonded to seal the opening.

[0205] The secondary battery in the implementation method is not limited to Figure 3 and Figure 4 The secondary battery shown can also be, for example, a... Figure 5 and Figure 6 The battery configuration shown is shown.

[0206] Figure 5 This is a partial notch perspective view schematically representing other examples of secondary batteries. Figure 6 It is Figure 5 The cross-sectional view of part B of the secondary battery shown is magnified.

[0207] Figure 5 and Figure 6 The secondary battery 100 shown has Figure 5 and Figure 6 Electrode group 1 shown Figure 5 The outer packaging component 2 and the electrolyte (not shown) are shown. The electrode assembly 1 and the electrolyte are housed within the outer packaging component 2. The electrolyte is held within the electrode assembly 1.

[0208] The outer packaging component 2 is made of a laminated film containing two resin layers and a metal layer sandwiched between them.

[0209] Electrode group 1 as follows Figure 6 The electrode assembly shown is a stacked type. The stacked type electrode assembly 1 has a structure in which a negative electrode 3 and a positive electrode 5 are alternately stacked while holding a separator 4 between them.

[0210] The electrode assembly 1 includes multiple negative electrodes 3. Each negative electrode 3 has a negative current collector 3a and a negative active material containing layer 3b supported on both sides of the negative current collector 3a. Furthermore, the electrode assembly 1 includes multiple positive electrodes 5. Each positive electrode 5 has a positive current collector 5a and a positive active material containing layer 5b supported on both sides of the positive current collector 5a.

[0211] Each negative electrode 3's negative current collector 3a includes a portion on one side containing a layer 3b on which no negative electrode active material is supported on any surface. This portion functions as a negative current collector tab 3c. Figure 6 As shown, the negative collector tab 3c does not overlap with the positive electrode 5. Furthermore, multiple negative collector tabs 3c are electrically connected to the strip-shaped negative terminal 6. The front end of the strip-shaped negative terminal 6 is led out to the outside of the outer packaging member 2.

[0212] Furthermore, although not shown, each positive electrode 5's positive current collector 5a includes a portion on one side containing a layer 5b on which no positive active material is supported on either surface. This portion functions as a positive current collector tab. The positive current collector tab, like the negative current collector tab 3c, does not overlap with the negative electrode 3. Moreover, the positive current collector tab is located on the opposite side of the electrode group 1 relative to the negative current collector tab 3c. The positive current collector tab is electrically connected to the strip-shaped positive terminal 7. The front end of the strip-shaped positive terminal 7 is located on the opposite side of the negative terminal 6 and is led out to the outside of the outer packaging member 2.

[0213] The secondary battery of the third embodiment includes the electrode of the second embodiment. That is, the secondary battery of the third embodiment includes an electrode containing the active material of the first embodiment. Therefore, the secondary battery of the third embodiment has excellent fast charge / discharge performance and cycle life performance.

[0214] (Fourth Implementation)

[0215] According to a fourth embodiment, a battery pack is provided. The battery pack includes a plurality of secondary batteries according to a third embodiment.

[0216] In the battery pack, the individual cells can be electrically connected in series or in parallel, or a combination of series and parallel connections can be configured.

[0217] Next, an example of the battery pack according to the fourth embodiment will be described with reference to the accompanying drawings.

[0218] Figure 7 This is a three-dimensional diagram that roughly represents an example of a battery pack. Figure 7 The battery pack 200 shown includes five individual cells 100a to 100e, four busbars 21, a positive electrode lead 22, and a negative electrode lead 23. Each of the five individual cells 100a to 100e is a secondary battery according to the third embodiment.

[0219] Busbar 21 connects, for example, the negative terminal 6 of a single cell 100a to the positive terminal 7 of the adjacent single cell 100b. In this manner, five single cells 100 are connected in series via four busbars 21. That is, Figure 7 The battery pack 200 is a battery pack of 5 connected in series. Although no example is shown, in a battery pack containing multiple individual cells electrically connected in parallel, for example, multiple negative terminals are connected to each other via a busbar, and multiple positive terminals are connected to each other via a busbar, so that multiple individual cells can be electrically connected.

[0220] The positive terminal 7 of at least one of the five individual cells 100a to 100e is electrically connected to the positive terminal lead 22 for external connection. In addition, the negative terminal 6 of at least one of the five individual cells 100a to 100e is electrically connected to the negative terminal lead 23 for external connection.

[0221] The battery pack of the fourth embodiment includes the secondary battery of the third embodiment. Therefore, the battery pack has excellent fast charge / discharge performance and cycle life performance.

[0222] (Fifth Implementation)

[0223] According to a fifth embodiment, a battery pack is provided. This battery pack includes the battery pack of the fourth embodiment. Alternatively, the battery pack may include a single secondary battery of the third embodiment instead of the battery pack of the fourth embodiment.

[0224] The battery pack may further include a protection circuit. This protection circuit controls the charging and discharging of the secondary battery. Alternatively, a circuit included in a device that uses the battery pack as a power source (e.g., electronic equipment, automobiles, etc.) can be used as the protection circuit for the battery pack.

[0225] Furthermore, the battery pack may also include external terminals for power supply. These external terminals are devices for supplying current from the secondary battery to the external source and / or supplying current from the external source to the secondary battery. In other words, when the battery pack is used as a power source, current is supplied to the external source via the external terminals. Additionally, when charging the battery pack, charging current (including regenerative energy from the power source of the vehicle, etc.) is supplied to the battery pack via the external terminals.

[0226] Next, an example of a battery pack according to an embodiment will be described with reference to the accompanying drawings.

[0227] Figure 8 This is an exploded perspective view that roughly represents an example of a battery pack. Figure 9 It means Figure 8 The diagram shows a block diagram of an example of the electrical circuitry of the battery pack.

[0228] Figure 8 and Figure 9 The battery pack 300 shown includes a container 31, a cover 32, a protective sheet 33, a battery pack 200, a printed circuit board 34, wiring 35, and an insulating plate (not shown).

[0229] Figure 8 The container 31 shown is a square container with a rectangular base. The container 31 is capable of accommodating the protective sheet 33, the battery pack 200, the printed circuit board 34, and the wiring 35. The cover 32 has a rectangular shape. The cover 32 accommodates the battery pack 200, etc., by covering the container 31. Although not shown, the container 31 and the cover 32 are provided with openings or connection terminals for connecting to external devices, etc.

[0230] The battery pack 200 includes multiple individual cells 100, positive electrode side lead 22, negative electrode side lead 23, and adhesive tape 24.

[0231] At least one of the plurality of individual cells 100 is a secondary cell according to the third embodiment. Each of the plurality of individual cells 100 is as follows: Figure 9 As shown, the individual cells 100 are electrically connected in series. Multiple individual cells 100 can also be connected in parallel, or a combination of series and parallel connections can be used. If multiple individual cells 100 are connected in parallel, the battery capacity increases compared to a series connection.

[0232] Adhesive tape 24 is used to bundle multiple individual cells 100 together. Alternatively, heat shrink tape can be used to secure the multiple individual cells 100 instead of adhesive tape 24. In this case, protective sheets 33 are placed on both sides of the battery pack 200, and the heat shrink tape is wrapped around the pack and then heat-shrinked to bundle the multiple individual cells 100 together.

[0233] One end of the positive electrode lead 22 is connected to the battery pack 200. One end of the positive electrode lead 22 is electrically connected to the positive electrode of one or more individual cells 100. One end of the negative electrode lead 23 is connected to the battery pack 200. One end of the negative electrode lead 23 is electrically connected to the negative electrode of one or more individual cells 100.

[0234] The printed circuit board 34 is disposed on a surface along one short side of the inner side of the receiving container 31. The printed circuit board 34 includes a positive-side connector 342, a negative-side connector 343, a thermistor 345, a protection circuit 346, wirings 342a and 343a, an external terminal 350 for power supply, positive-side wiring 348a, and negative-side wiring 348b. One main surface of the printed circuit board 34 faces one side of the battery pack 200. An insulating plate (not shown) is sandwiched between the printed circuit board 34 and the battery pack 200.

[0235] The other end 22a of the positive lead 22 is electrically connected to the positive connector 342. The other end 23a of the negative lead 23 is electrically connected to the negative connector 343.

[0236] A thermistor 345 is fixed to a main surface of a printed circuit board 34. The thermistor 345 detects the temperature of each individual cell 100 and sends its detection signal to a protection circuit 346.

[0237] An external terminal 350 for power supply is fixed to another main surface of the printed circuit board 34. The external terminal 350 for power supply is electrically connected to a device located outside the battery pack 300. The external terminal 350 for power supply includes a positive terminal 352 and a negative terminal 353.

[0238] The protection circuit 346 is fixed to another main surface of the printed circuit board 34. The protection circuit 346 is connected to the positive terminal 352 via a positive side wiring 348a. The protection circuit 346 is connected to the negative terminal 353 via a negative side wiring 348b. Furthermore, the protection circuit 346 is electrically connected to the positive connector 342 via wiring 342a. The protection circuit 346 is electrically connected to the negative connector 343 via wiring 343a. Moreover, the protection circuit 346 is electrically connected to each of the plurality of individual cells 100 via wiring 35.

[0239] The protective sheet 33 is disposed on the two inner sides of the receiving container 31 along the long side and on the inner side of the receiving container 31 along the short side, which is adjacent to the battery pack 200 and the printed circuit board 34. The protective sheet 33 is made of, for example, resin or rubber.

[0240] The protection circuit 346 controls the charging and discharging of multiple individual batteries 100. In addition, based on the detection signal sent from the thermistor 345, or the detection signal sent from each individual battery 100 or battery pack 200, the protection circuit 346 blocks the electrical connection between the protection circuit 346 and the external terminals 350 (positive terminal 352, negative terminal 353) used to power external devices.

[0241] As a detection signal sent from the thermistor 345, examples include a signal that the temperature of a single cell 100 is above a predetermined temperature. As a detection signal sent from each single cell 100 or the battery pack 200, examples include signals that detect overcharging, over-discharging, and overcurrent in a single cell 100. In the case of detecting overcharging in each single cell 100, the battery voltage, or the positive or negative electrode potential, can be detected. In the latter case, a lithium electrode used as a reference electrode is inserted into each single cell 100.

[0242] It should be noted that the protection circuit 346 can also be a circuit contained in a device that uses the battery pack 300 as a power source (such as electronic devices, automobiles, etc.).

[0243] Furthermore, as described above, the battery pack 300 includes an external terminal 350 for power supply. Therefore, the battery pack 300 can output current from the battery pack 200 to an external device and input current from an external device into the battery pack 200 via the external terminal 350. In other words, when using the battery pack 300 as a power source, current from the battery pack 200 is supplied to the external device via the external terminal 350. Furthermore, when charging the battery pack 300, charging current from the external device is supplied to the battery pack 300 via the external terminal 350. When using the battery pack 300 as a vehicle battery, the regenerative energy from the vehicle's power source can be utilized as the charging current from the external device.

[0244] It should be noted that the battery pack 300 may also include multiple battery groups 200. In this case, the multiple battery groups 200 may be connected in series, in parallel, or a combination of series and parallel connections. Furthermore, the printed circuit board 34 and wiring 35 may be omitted. In this case, the positive terminal lead 22 and the negative terminal lead 23 may be used as the positive terminal 352 and negative terminal 353 of the external terminal 350 for power supply, respectively.

[0245] Such battery packs are used, for example, in applications requiring excellent cycle performance when drawing high currents. Specifically, they are used as power sources for electronic devices, stationary batteries, and in-vehicle batteries for various vehicles. Examples of electronic devices include digital cameras. This battery pack is particularly suitable for use as an in-vehicle battery.

[0246] The battery pack of the fifth embodiment includes the secondary battery of the third embodiment or the battery pack of the fourth embodiment. Therefore, the battery pack has excellent fast charge / discharge performance and cycle life performance.

[0247] (Sixth Implementation Method)

[0248] According to a sixth embodiment, a vehicle is provided. This vehicle is equipped with a battery pack according to a fifth embodiment.

[0249] In the vehicle, the battery pack is, for example, a component that recovers regenerative energy from the vehicle's kinetic energy. The vehicle may also include a mechanism (Regenerator) that converts the vehicle's kinetic energy into regenerative energy.

[0250] Examples of vehicles include two- to four-wheeled hybrid electric vehicles, two- to four-wheeled electric vehicles, electric bicycles, and railway vehicles.

[0251] There are no particular restrictions on the location of the battery pack in a vehicle. For example, when mounting the battery pack in a car, it can be installed in the engine compartment, at the rear of the vehicle body, or under the seats.

[0252] The vehicle can also be equipped with multiple battery packs. In this case, the batteries contained in each battery pack can be electrically connected in series, in parallel, or a combination of series and parallel connections. For example, if each battery pack contains battery groups, the battery groups can be electrically connected in series, in parallel, or a combination of series and parallel connections. Alternatively, if each battery pack contains a single battery, the individual batteries can be electrically connected in series, in parallel, or a combination of series and parallel connections.

[0253] Next, an example of a vehicle according to the implementation method will be described with reference to the accompanying drawings.

[0254] Figure 10 This is a partial perspective view that roughly represents an example of a vehicle.

[0255] Figure 10 The vehicle 400 shown includes a vehicle body 40 and a battery pack 300 according to the fifth embodiment. Figure 10In the example shown, vehicle 400 is a four-wheeled car.

[0256] The vehicle 400 can also be equipped with multiple battery packs 300. In this case, the batteries (e.g., single cells or battery packs) contained in the battery pack 300 can be connected in series, in parallel, or a combination of series and parallel connections.

[0257] exist Figure 10 The diagram illustrates an example where the battery pack 300 is mounted in the engine compartment located at the front of the vehicle body 40. As mentioned above, the battery pack 300 can also be mounted, for example, at the rear of the vehicle body 40 or under the seats. The battery pack 300 can be used as a power source for the vehicle 400. Furthermore, the battery pack 300 can recover regenerative energy from the power source of the vehicle 400.

[0258] Next, refer to Figure 11 The implementation scheme of the vehicle in the implementation method is described.

[0259] Figure 11 This is a diagram that roughly represents an example of a control system for the electrical system in a vehicle. Figure 11 The vehicle 400 shown is an electric vehicle.

[0260] Figure 11 The vehicle 400 shown includes a vehicle body 40, a vehicle power supply 41, a higher-level control device for the vehicle power supply 41 namely a vehicle ECU (Electric Control Unit) 42, external terminals (terminals for connecting external power supply) 43, a converter 44, and a drive motor 45.

[0261] Vehicle 400 mounts vehicle power supply 41 in, for example, the engine compartment, the rear of the vehicle body, or under the seats. It should be noted that... Figure 11 In the vehicle 400 shown, the mounting location of the vehicle power supply 41 is schematically represented.

[0262] The vehicle power supply 41 includes multiple (e.g., three) battery packs 300a, 300b and 300c, a battery management unit (BMU) 411 and a communication bus 412.

[0263] Battery pack 300a includes battery pack 200a and battery pack monitoring device 301a (e.g., VTM: Voltage Temperature Monitoring). Battery pack 300b includes battery pack 200b and battery pack monitoring device 301b. Battery pack 300c includes battery pack 200c and battery pack monitoring device 301c. Battery packs 300a to 300c are the same battery packs as battery pack 300 described above, and battery packs 200a to 200c are the same battery packs as battery pack 200 described above. Battery packs 200a to 200c are electrically connected in series. Battery packs 300a, 300b, and 300c can be removed independently and can be replaced with other battery packs 300.

[0264] Each of the battery packs 200a to 200c comprises a plurality of individual cells connected in series. At least one of the individual cells is a secondary battery according to the third embodiment. The battery packs 200a to 200c are charged and discharged via the positive terminal 413 and the negative terminal 414, respectively.

[0265] The battery management device 411 communicates with the battery pack monitoring devices 301a-301c, and collects information about voltage, temperature, etc., for each individual cell 100 included in the battery packs 200a-200c contained in the vehicle power supply 41. Thus, the battery management device 411 collects information regarding the maintenance of the vehicle power supply 41.

[0266] The battery management device 411 and the battery monitoring devices 301a-301c are connected via a communication bus 412. In the communication bus 412, one set of communication lines is shared by multiple nodes (the battery management device 411 and one or more battery monitoring devices 301a-301c). The communication bus 412 is, for example, a communication bus based on the CAN (Control Area Network) standard.

[0267] The battery monitoring devices 301a to 301c measure the voltage and temperature of each individual cell constituting the battery packs 200a to 200c based on communication-based instructions from the battery management device 411. However, the temperature can be measured at only a few locations within a battery pack, or the temperature of all individual cells can be measured.

[0268] The vehicle power supply 41 may also have an electromagnetic contactor (e.g., to switch the electrical connection between the positive terminal 413 and the negative terminal 414) to enable or disable the connection. Figure 11The switching device 415 shown is included. The switching device 415 includes a pre-charge switch (not shown) that is open when charging the battery packs 200a-200c, and a main switch (not shown) that is open when the output from the battery packs 200a-200c is supplied to a load. Both the pre-charge switch and the main switch have relay circuits (not shown) that are switched on or off by a signal supplied to a coil disposed near the switching element. The electromagnetic contactor, such as the switching device 415, is controlled based on control signals from the vehicle ECU 42 that control the operation of the battery management device 411 or the vehicle 400 as a whole.

[0269] The converter 44 converts the input DC voltage into a high-voltage 3-phase AC voltage for motor drive. The 3-phase output terminals of the converter 44 are connected to the 3-phase input terminals of the drive motor 45. The converter 44 is controlled based on control signals from the vehicle ECU 42 used to control the operation of the battery management device 411 or the vehicle as a whole. The output voltage from the converter 44 is adjusted by controlling the converter 44.

[0270] The drive motor 45 is rotated by electricity supplied by the converter 44. The driving force generated by the rotation of the drive motor 45 is transmitted to the axle and drive wheel W, for example, through a differential gear unit.

[0271] Furthermore, although not shown, vehicle 400 is equipped with a regenerative braking mechanism (regenerator). When braking vehicle 400, the regenerative braking mechanism causes drive motor 45 to rotate, converting kinetic energy into regenerative energy as electrical energy. The regenerative energy recovered by the regenerative braking mechanism is input to converter 44, where it is converted into direct current. The converted direct current is input to vehicle power supply 41.

[0272] One terminal of the connecting line L1 is connected to the negative terminal 414 of the vehicle power supply 41. The other terminal of the connecting line L1 is connected to the negative input terminal 417 of the converter 44. On the connecting line L1, between the negative terminal 414 and the negative input terminal 417, a current detection unit (current detection circuit) 416 from the battery management device 411 is provided.

[0273] One terminal of the connecting line L2 is connected to the positive terminal 413 of the vehicle power supply 41. The other terminal of the connecting line L2 is connected to the positive input terminal 418 of the converter 44. A switching device 415 is provided on the connecting line L2 between the positive terminal 413 and the positive input terminal 418.

[0274] External terminal 43 is connected to battery management device 411. External terminal 43 can be connected to an external power source, for example.

[0275] The vehicle ECU 42 responds to input from the driver and other operators, and coordinates with other management and control devices, including the battery management device 411, to control the vehicle power supply 41, switching device 415, and converter 44. Through the coordinated control of the vehicle ECU 42 and others, it controls the output of power from the vehicle power supply 41 and the charging of the vehicle power supply 41, thus managing the overall vehicle 400. Data regarding the maintenance of the vehicle power supply 41, such as the remaining capacity of the vehicle power supply 41, is transmitted between the battery management device 411 and the vehicle ECU 42 via a communication line.

[0276] The vehicle of the sixth embodiment is equipped with the battery pack of the fifth embodiment. Due to the excellent fast charge / discharge performance of the battery pack, the vehicle exhibits high performance. Furthermore, due to the excellent cycle life performance of the battery pack, the vehicle has high reliability.

[0277] [Example]

[0278] The above-described embodiments will be further described in detail below based on examples. However, the present invention is not limited to the embodiments described below.

[0279] <Synthesis>

[0280] (Example 1)

[0281] As described above, a titanium-niobium-molybdenum composite oxide was synthesized.

[0282] As raw materials, ammonium niobate, ammonium molybdate, and titanium tetraisopropoxide were prepared. These raw materials were weighed according to a specified composition ratio. For ammonium niobate and ammonium molybdate, solution A was prepared by dissolving them in pure water. Next, titanium tetraisopropoxide was added to a 1M aqueous oxalic acid solution and dissolved by heating and stirring to prepare solution B. After mixing solutions A and B, the pH was adjusted to 7 by adding ammonia solution while heating and stirring to obtain a sol. The solvent in the sol was evaporated by spray drying at a temperature set to 180°C to obtain a white precursor powder. The precursor powder was placed in an alumina crucible and calcined in the atmosphere at 700°C for 4 hours. Afterward, the calcined material was dry-milled, and the particle size was adjusted by classifying the milled material. The active material powder was obtained by operating as described above.

[0283] (Example 2)

[0284] The temperature of the calcination precursor was changed to 800°C. Otherwise, the composite oxide was synthesized using the same method as in Example 1 to obtain the active material powder.

[0285] (Example 3)

[0286] The temperature of the calcination precursor was changed to 900°C. Otherwise, the composite oxide was synthesized using the same method as in Example 1 to obtain the active material powder.

[0287] (Examples 4-7)

[0288] The composition ratio of the precursor was changed by adjusting the weighing ratio of the raw materials, and the firing temperature of the precursor was changed as follows. Otherwise, the composite oxide was synthesized by the same method as in Example 1 to obtain the active material powder. The firing temperature was set to 700°C in Example 4, 750°C in Example 5, 800°C in Example 6, and 900°C in Example 7.

[0289] (Comparative Example 1)

[0290] The temperature for calcining the precursor powder was changed to 600°C. Otherwise, the composite oxide was synthesized using the same method as in Example 1 to obtain the active material powder.

[0291] <Measurement>

[0292] The powders obtained in the above examples and comparative examples were observed using scanning transmission electron microscopy. Specifically, as detailed above, the fine structure was observed using a 10 nm × 10 nm image obtained from a STEM-HAADF image with spherical aberration correction. Furthermore, wide-angle X-ray scattering measurements were performed. The measurements were conducted as detailed above. The crystal structure was determined using the Rietveld method from the obtained spectra. In addition, ICP-luminescence analysis, HAXPES measurements, and Raman spectroscopy were performed. A portion of the measurement results are described in detail.

[0293] For the composite oxide obtained in Example 1, it was confirmed that... Figure 1 and Figure 2 The crystal structures exist in a mixed manner.

[0294] For the composite oxide obtained in Example 1, the metal ratio was calculated by ICP analysis, and the result was Ti:Nb:Mo = 0.23:1.00:0.18. The valence was evaluated by HAXPES determination. Ti elemental analysis was observed to originate from Ti2p within the range of 459 ± 0.4 eV. 3 / 2 The single peak apex identified it as tetravalent. Nb was observed to originate from Nb5d in the range of 207.5 ± eV. 3 / 2 The single peak at the apex of the molar indicates a pentavalent molarity. Mo was observed at 232.2 ± 0.3 eV originating from the hexavalent molar 3d group. 5 / 2The peak was observed, and it was confirmed that different peaks existed at values ​​1 eV lower than this peak, thus identifying a mixture of 5-valent and 6-valent peaks. Based on the mixing ratio of the peaks, it was inferred that the 5-valent and 6-valent elements were mixed in a 7:3 ratio, with an assumed average valence of 5.3. The composition calculated based on this assumption became Ti. 0.23 NbMo 0.18 O 3.47 Therefore, b = 0.23, c = 0.18, and d = 3.47.

[0295] For the composite oxide obtained in Example 2, it was confirmed that... Figure 1 and Figure 2 The crystal structures exist in a mixed manner.

[0296] For the composite oxide obtained in Example 2, the metal ratio was calculated by ICP analysis, and the result was Ti:Nb:Mo = 0.23:1.00:0.18. The valence was evaluated by HAXPES determination using the same method as in Example 1, and Ti was set to 4 valence, Nb to 5 valence, and Mo to 5.6 valence. The composition formula calculated from the valence is Ti. 0.23 NbMo 0.18 O 3.49 Therefore, b = 0.23, c = 0.18, and d = 3.49.

[0297] For the composite oxide obtained in Example 3, the structural analysis results indicate that it is only Figure 1 The crystal structure shown is a single phase.

[0298] For the composite oxide obtained in Example 3, the metal ratio was calculated by ICP analysis, and the result was Ti:Nb:Mo = 0.23:1.00:0.15. The composition formula calculated from the number of elements and crystal structure is Ti 0.23 NbMo 0.15 O 3.45 The valence was evaluated using the same method as in Example 1 and determined by HAXPES. The results showed that Ti was set to a valence of 4, Nb to 5, and Mo to 6. The compositional formula calculated from the valence became Ti. 0.23 NbMo 0.15 O 3.41 Therefore, b = 0.23, c = 0.15, and d = 3.41.

[0299] Although details are omitted, in Examples 4 and 5, the following were obtained: Figure 1 and Figure 2 A composite oxide with a mixed crystal structure. In Examples 6 and 7, the same as in Example 3 was obtained. Figure 1 The crystal structure shown is a single-phase composite oxide. It is represented by the general formula Li.a M b NbMo c O d The composition is as shown in Table 1 below.

[0300] The composite oxide obtained in Comparative Example 1 was observed for its fine structure using STEM-HAADF imaging. The results confirmed that the ReO3 blocks exhibited varying sizes within the field of view and did not possess a periodic crystal structure connected by shared octahedral edges. Therefore, it was identified as… Figure 2 The crystal structure shown is illustrated. It should be noted that, in different views, connections shared by the vertices of the tetrahedron were also identified.

[0301] For the composite oxide obtained in Comparative Example 1, the metal ratio was calculated by ICP analysis, and the result was Ti:Nb:Mo = 0.23:1.00:0.23. The valence was evaluated by HAXPES determination using the same method as in Example 1, and the valence of Ti was set to 4, Nb to 5, and Mo to 5.5. The composition formula calculated from the valence is Ti 0.23 NbMo0. 23 O 3.59 Therefore, b = 0.23, c = 0.23, and d = 3.59.

[0302] The spectra obtained by micro Raman spectrometry (excitation wavelength: 532 nm) of the composite oxides of Examples 1-3 and Comparative Example 1 are shown below. Figure 12 In the figure, dashed lines R1 and R2, with their positions along the horizontal axis relative to the Raman peaks P1 and P2 in each example, serve as visually easily grasped references, indicating a displacement of 640 cm. 1 and displacement of 920cm- 1 The location. For example... Figure 12 As shown, the Raman spectra of any composite oxide are all at a shift of 640 ± 10 cm⁻¹. 1 and 920±20cm- 1 The peaks are then observed. Each peak is designated as Raman peak P1 and P2, and their specific displacements (S1 and S2) are shown in Table 1 below. Furthermore, Table 1 also shows the displacement difference S2-S1 and the composition derived from ICP analysis and HAXPES measurements.

[0303] Table 4

[0304]

[0305] As shown in Table 1, any of Examples 1-7 and Comparative Example 1 can synthesize a product having the general formula Li described above. a Mb NbMo c O d The composition is represented by a composite oxide with a bulk structure of rhenium oxide consisting of octahedral structures. Regarding Examples 1-7, the shift difference S2-S1 in the Raman spectra is 285 cm⁻¹. -1 That's all. Therefore, it was found that many Schottky-type defects were introduced. In contrast, in Comparative Example 1, the displacement difference S2-S1 remained below 285 cm. -1 .

[0306] <Battery Performance Evaluation>

[0307] Electrodes were fabricated using the active material powders obtained in the above examples and comparative examples, as described below.

[0308] First, a slurry is prepared by dispersing 100 parts by weight of an active material, 6 parts by weight of a conductive agent, and 4 parts by weight of a binder in a solvent. The active material is a composite powder obtained by the above method. The conductive agent is a mixture of acetylene black, carbon nanotubes, and graphite. The binder is a mixture of carboxymethyl cellulose (CMC) and styrene-butadiene rubber (SBR). Pure water is used as the solvent.

[0309] Next, the obtained slurry is coated onto one side of the current collector, and the coating is dried to form an active material containing layer. A 12 μm thick aluminum foil is used as the current collector. Then, the current collector and the active material containing layer are pressed together to obtain the electrode. The electrode has a unit area weight of 40 g / m². 2 .

[0310] The non-aqueous electrolyte is prepared as follows. An electrolyte salt is dissolved in an organic solvent to obtain a liquid non-aqueous electrolyte. LiPF6 is used as the electrolyte salt. The molar concentration of LiPF6 in the non-aqueous electrolyte is set to 1 mol / L. A mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) is used as the organic solvent. The volume ratio of EC to DEC is 1:2.

[0311] Using the electrode obtained by the above method as the working electrode, and lithium metal foil as the counter electrode and reference electrode, a three-electrode beaker battery is fabricated using the non-aqueous electrolyte prepared by the above method.

[0312] For each battery fabricated, cycle life and discharge rate performance were evaluated as follows. The evaluation temperature was set at 25°C, and the lower limit of the potential range, based on the lithium reference potential, was set at 0.7V (vs. Li / Li). + The upper limit potential is set to 3.0V (vs. Li / Li). +The charging and discharging of the system were performed. Charging was conducted in constant current-constant voltage mode, and discharging was conducted in constant current mode. Cycle life was evaluated by repeatedly performing charge-discharge cycles at a current value of 1C, and the capacity retention rate of the discharge in the 1st and 30th cycles was calculated (cycle capacity retention rate (%) = [discharge capacity in the 30th cycle / discharge capacity in the 1st cycle] × 100%). Discharge rate performance was evaluated by fixing the charging current at 1C and only varying the discharge current value, and the capacity retention rate of the discharge at 5C relative to the discharge capacity at 0.2C was calculated (discharge rate capacity retention rate (%) = [discharge capacity at 5C / discharge capacity at 0.2C] × 100%). The calculated capacity retention rates are summarized in Table 2 below.

[0313] Table 2

[0314]

[0315] The composite oxides contained in the active substances obtained in Examples 1-7 correspond to those of the general formula Li described above. a M b NbMo c O d This indicates that the shift difference S2-S1 in the Raman spectrum is 285 cm⁻¹. 1 In contrast to the compounds described above, the composite oxide obtained in Comparative Example 1, while satisfying the above general formula, does not satisfy the shift difference S2-S1. As shown in Table 2, the active materials of Examples 1-7 exhibit higher fast charge / discharge performance and cycle life performance compared to the composite oxide of Comparative Example 1.

[0316] In detail, regarding the cycle capacity retention rate, compared to Comparative Example 1, Examples 1-7 tend to show an increase in the amount of defects. This is believed to be due to the increased electronic conductivity resulting from the inclusion of defects within the structure, which allows the conductive pathway to be maintained during cycling. On the other hand, in Examples 1-7, as the displacement difference S2-S1 increases, i.e., the number of defects increases, the discharge rate retention rate tends to decrease. This is believed to be due to the effect of hindering Li diffusion by including defects within the structure.

[0317] Based on one or more embodiments and examples described above, an active material comprising a composite oxide is provided. This composite oxide has a crystal structure comprising a rhenium oxide-type bulk structure containing an octahedral structure composed of oxygen and metal elements, wherein the octahedral structure is formed by shared vertices, and is expressed in the general formula Li. a M b NbMo c O dThe expression is given. In this expression, M is any one of the following groups: Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si. The subscripts in the expression satisfy the relationships 0 ≤ a ≤ b + 2 + 3c, 0 ≤ b ≤ 1.5, 0 ≤ c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.50. In the micro Raman spectrophotometry at an excitation wavelength of 532 nm, at 640 ± 10 cm⁻¹... 1 The Raman shift S1 of the Raman peak P1 originating from the Mo-O bond appears at 920±20 cm⁻¹. -1 The difference between the Raman shift S2 of the Raman peak P2, which originates from the Nb-O bond, and S1 is 285 cm. -1 The above describes the active material, which can provide electrodes for a secondary battery that achieves excellent fast charge / discharge performance and cycle life, a secondary battery and battery pack that achieve excellent fast charge / discharge performance and cycle life, and a vehicle equipped with the battery pack.

[0318] It should be noted that the above-described implementation methods can be summarized into the following technical solutions.

[0319] (Technical Solution 1)

[0320] An active material comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure, wherein the rhenium oxide-type bulk structure contains an octahedral structure composed of oxygen and a metallic element, and is formed by sharing the vertices of the octahedral structure, and the composite oxide is in the form of the general formula Li. a M b NbMo c O d M is selected from any one or more of the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, with 0≤a≤b+2+3c, 0≤b≤1.4, 0≤c≤0.5, and 2.33≤d / (1+b+c)≤2.50. In the micro Raman spectrophotometer at an excitation wavelength of 532 nm for the aforementioned composite oxide, M is located at 640±10 cm⁻¹. -1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. -1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. -1 above.

[0321] (Technical Solution 2)

[0322] An active material comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure, wherein the rhenium oxide-type bulk structure contains an octahedral structure composed of oxygen and a metallic element, and is formed by sharing the vertices of the octahedral structure, and the composite oxide is in the form of the general formula Li. a M b NbMo c O d M is selected from any one or more of the group consisting of Ti, V, Ta, Fe, Co, Mn, Ni, Bi, Sb, As, P, Cr, W, B, Na, K, Mg, Al, Ca, Y, and Si, with 0≤a≤b+2+3c, 0≤b≤1.5, 0≤c≤0.5, and 2.33≤d / (1+b+c)≤2.50. In the micro Raman spectrophotometer at an excitation wavelength of 532 nm for the aforementioned composite oxide, M is located at 640±10 cm⁻¹. -1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. -1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. -1 above.

[0323] (Technical Solution 3)

[0324] According to the above technical solution 1 or 2, the crystal structure includes multiple rhenium oxide blocks of different sizes, and the rhenium oxide blocks are shared by at least octahedral edges without being periodically connected.

[0325] (Technical Solution 4)

[0326] An electrode comprising the active material described in any one of the above-described technical solutions 1 to 3.

[0327] (Technical Solution 5)

[0328] According to the above technical solution 4, it includes an active substance containing the above-mentioned active substance layer.

[0329] (Technical Solution 6)

[0330] A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, wherein the positive electrode or the negative electrode is the electrode described in technical solution 4 or 5 above.

[0331] (Technical Solution 7)

[0332] A battery pack comprising the secondary battery described in technical solution 6 above.

[0333] (Technical Solution 8)

[0334] According to the above technical solution 7, it further includes external terminals for power supply and protection circuit.

[0335] (Technical Solution 9)

[0336] According to the above technical solution 7 or 8, it has multiple secondary batteries, which are electrically connected in series, in parallel, or in a combination of series and parallel connections.

[0337] (Technical Solution 10)

[0338] A vehicle comprising a battery pack as described in any one of the above-mentioned technical solutions 7 to 9.

[0339] (Technical Solution 11)

[0340] According to the above technical solution 10, it includes a mechanism for converting the kinetic energy of the vehicle into regenerative energy.

[0341] Several embodiments of the present invention have been described, but these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. An active substance comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure, wherein the rhenium oxide-type bulk structure contains an octahedral structure composed of oxygen and a metallic element, and is formed by sharing vertices of the octahedral structure. The composite oxide is in the general formula Li a M b NbMo c O d This means that M is selected from any one or more of the groups consisting of Ti, Zr, and Si, where 0 ≤ a ≤ b + 2 + 3c, 0 < b ≤ 1.4, 0 < c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.

50. In the micro Raman spectra of the composite oxide at an excitation wavelength of 532 nm, the value is located at 640 ± 10 cm⁻¹. -1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. -1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. -1 above.

2. An active substance comprising a composite oxide having a crystal structure comprising a rhenium oxide-type bulk structure, wherein the rhenium oxide-type bulk structure contains an octahedral structure composed of oxygen and a metallic element, and is formed by sharing vertices of the octahedral structure. The composite oxide is in the general formula Li a M b NbMo c O d This means that M is selected from any one or more of the groups consisting of Ti, Zr, and Si, where 0 ≤ a ≤ b + 2 + 3c, 0 < b ≤ 1.5, 0 < c ≤ 0.5, and 2.33 ≤ d / (1 + b + c) ≤ 2.

50. In the micro Raman spectra of the composite oxide at an excitation wavelength of 532 nm, the value is located at 640 ± 10 cm⁻¹. -1 The displacement S1 of the Raman peak P1 originating from the Mo-O bond is located at 920±20cm. -1 The difference in displacement S2 of the Raman peak P2 originating from the Nb-O bond is 285 cm. -1 above.

3. The active substance according to claim 2, wherein, The crystal structure comprises multiple rhenium oxide blocks of different sizes, and the rhenium oxide blocks are shared at least by octahedral edges without being periodically connected.

4. The active substance according to any one of claims 1 to 3, wherein, The M contains at least Ti.

5. An electrode comprising the active material according to any one of claims 1 to 4.

6. The electrode according to claim 5, wherein, The electrode comprises an active material containing the active material.

7. A secondary battery comprising a positive electrode, a negative electrode, and an electrolyte. The positive electrode or the negative electrode is the electrode according to claim 5 or 6.

8. A battery pack comprising the secondary battery of claim 7.

9. The battery pack according to claim 8, wherein, The battery pack further includes external terminals for power supply, and Protection circuit.

10. The battery pack according to claim 8 or 9, wherein, The battery pack includes multiple of the aforementioned secondary batteries. The secondary batteries are electrically connected in series, in parallel, or in a combination of series and parallel connections.

11. A vehicle comprising the battery pack of any one of claims 8 to 10.

12. The vehicle according to claim 11, wherein, The vehicle includes a mechanism for converting the vehicle's kinetic energy into regenerative energy.

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