All-solid-state battery

Abstract

To reduce a self-discharge amount.SOLUTION: An all-solid-state battery includes: a positive electrode layer; a separator layer; and a negative electrode layer. The all-solid-state battery satisfies the following relations of "the equation (1): 0.99≤Sa0 / Sc0≤1.01", "the equation (2): 1.00≤Sa1 / Sa0≤1.13, and "the equation (3): 0.93≤Sc1 / Sc0≤1.02". Sc0 indicates an area of the positive electrode layer when SOC is 0%. Sc1 indicates an area of the positive electrode layer when SOC is 100%. Sa0 indicates an area of the negative electrode layer when SOC is 0%. Sa1 indicates an area of the negative electrode layer when SOC is 100%.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to all-solid-state batteries. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2021-061102 (Patent Document 1) discloses that, in a plan view, the electrode active material layer is in the same position as the counter electrode active material layer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-061102 Summary of the Invention [Problem to be solved by the invention]

[0004] An all-solid-state battery (hereinafter, abbreviated as "battery") includes a power generating element. The power generating element is formed by stacking a positive electrode layer, a separator layer, and a negative electrode layer. The power generating element has a side end face. The side end face refers to an end face parallel to the stacking direction (thickness direction). Generally, the side end face has a step. The step is formed because the areas of the layers are different. For example, even if the positive electrode layer and the negative electrode layer are misaligned during stacking, the positive electrode layer does not protrude from the negative electrode layer, so the negative electrode layer can have a larger area than the positive electrode layer.

[0005] Eliminating the step on the side end surface is also being considered. That is, a structure in which the positive electrode layer and the negative electrode layer are flush with each other on the side end surface (hereinafter also referred to as a "flush structure") is being considered. A flush structure is simple. By simplifying the structure, for example, improvements in material efficiency and mass productivity are expected. For example, a flush structure can be formed by cutting the power generating element after it is formed (laminated). However, a flush structure tends to increase the amount of self-discharge. Therefore, the present disclosure aims to reduce the amount of self-discharge. [Means for solving the problem]

[0006] 1. An all-solid-state battery in one aspect of the present disclosure includes a positive electrode layer, a separator layer, and a negative electrode layer. The separator layer is disposed between the positive electrode layer and the negative electrode layer. The all-solid-state battery satisfies the relationships of the following formulas (1) to (3). 0.99≦S a0 / S c0 ≦1.01 (1) 1.00≦S a1 / S a0 ≦1.13 (2) 0.93≦S c1 / S c0 ≦1.02 (3) In the above formulas (1) to (3), S c0 indicates the area of ​​the positive electrode layer when the SOC is 0%. c1 indicates the area of ​​the positive electrode layer when the SOC is 100%. a0 indicates the area of ​​the negative electrode layer when the SOC is 0%. a1 indicates the area of ​​the negative electrode layer when the SOC is 100%.

[0007] "SOC (State of Charge)" indicates the ratio of the battery's current charge capacity to its fully charged capacity. SOC is displayed as a percentage. "SOC=0%" indicates a fully discharged state. "SOC=100%" indicates a fully charged state.

[0008] In general, the positive electrode layer and the negative electrode layer may expand during charging. Each layer may expand not only in the thickness direction but also in the planar direction. The planar direction refers to any direction perpendicular to the thickness direction. Expansion in the planar direction indicates an increase in area. When the side end surfaces of the positive electrode layer and the negative electrode layer are flush with each other, the positive electrode layer and the negative electrode layer may expand together in the planar direction, causing contact between the positive electrode layer and the negative electrode layer. It is believed that contact between the positive electrode layer and the negative electrode layer in the planar direction may increase the self-discharge amount.

[0009] The relationship in formula (1) above indicates that the positive electrode layer and the negative electrode layer are flush with each other in a discharged state. The relationship in formula (2) above indicates that the area of ​​the negative electrode layer does not change or can expand by up to 13% during charging. The relationship in formula (3) above indicates that the area of ​​the positive electrode layer can expand by up to 2% or shrink during charging. When the relationships in formulas (2) and (3) above are satisfied, a reduction in the amount of self-discharge is expected. During charging, the timing and direction of area change between the positive electrode layer and the negative electrode layer do not match, which is thought to reduce the opportunity for contact between the positive electrode layer and the negative electrode layer.

[0010] 2. The all-solid-state battery described in the above item "1" may satisfy, for example, the relationship of the following formula (3)'. 0.93≦S c1 / S c0 <1.00 (3)'

[0011] The relationship of the above formula (3)' indicates that the area of ​​the positive electrode layer shrinks during charging. As shown in the above formula (2), the area of ​​the negative electrode layer may not change or may expand during charging. That is, during charging, the area change of the positive electrode layer and the area change of the negative electrode layer may be in opposite directions. Therefore, it is expected that the chance of contact between the positive electrode layer and the negative electrode layer will be further reduced.

[0012] 3. In the all-solid-state battery according to the above item "1" or "2," the negative electrode layer may contain, for example, at least one selected from the group consisting of lithium titanium composite oxide (LTO), titanium niobium composite oxide (TNO), graphite, and hard carbon.

[0013] The negative electrode layer contains a negative electrode active material such as LTO. The negative electrode active material described in "3" above does not expand during charging or has a low expansion rate during charging. It is expected that the use of the negative electrode active material described in "3" above will make it easier to satisfy the relationship in formula (2) above.

[0014] 4. In the all-solid-state battery according to any one of the above items "1" to "3," the positive electrode layer may contain, for example, at least one selected from the group consisting of lithium nickel cobalt manganese composite oxide (NCM), lithium nickel cobalt aluminum composite oxide (NCA), and lithium iron phosphate (LFP).

[0015] The positive electrode layer contains a positive electrode active material such as NCM. The positive electrode active material described in "4" above may shrink during charging. It is expected that the use of the positive electrode active material described in "4" above will make it easier to satisfy the relationship between the above formulas (3) and (3)'.

[0016] 5. An all-solid-state battery according to one aspect of the present disclosure includes a positive electrode layer, a separator layer, and a negative electrode layer. The positive electrode layer includes at least one material selected from the group consisting of NCM, NCA, and LFP. The separator layer is disposed between the positive electrode layer and the negative electrode layer. The negative electrode layer includes at least one material selected from the group consisting of LTO, TNO, graphite, and hard carbon. The all-solid-state battery satisfies the relationships of the above formulas (1), (2), and (3)'.

[0017] Hereinafter, an embodiment of the present disclosure (hereinafter may be abbreviated as "the present embodiment") and an example of the present disclosure (hereinafter may be abbreviated as "the present example") will be described. However, the present embodiment and the example do not limit the technical scope of the present disclosure. The present embodiment and the example are illustrative in all respects. The present embodiment and the example are non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is originally intended that any configuration may be extracted from the present embodiment and the example and that they may be arbitrarily combined. [Brief explanation of the drawings]

[0018] [Figure 1] FIG. 1 is a conceptual diagram of an all-solid-state battery according to this embodiment. [Figure 2] FIG. 2 is a table showing the configurations of the test batteries and the self-discharge amounts. DETAILED DESCRIPTION OF THE INVENTION

[0019] The terms "comprise," "include," "have," and variations thereof (e.g., "consisting of") are open-ended. Open-ended terms may or may not include additional elements in addition to the required elements. The term "consisting of" is closed-ended. However, even closed-ended terms do not exclude additional elements that are normally incidental impurities or unrelated to the disclosed technology. The term "consisting essentially of..." is semi-closed. Semi-closed terms allow for the addition of elements that do not substantially affect the basic and novel characteristics of the disclosed technology.

[0020] Numerical ranges such as "m to n%" include the upper and lower limits unless otherwise specified. In other words, "m to n%" indicates a numerical range of "m% to n%." "m% to n%" includes "more than m% but less than n%." The measured value may be the average value of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. In general, the more measurements are made, the more reliable the average value is expected to be. The measured value may be rounded off based on the number of significant digits. The measured value may include errors, for example, due to the detection limit of the measuring device.

[0021] Geometric terms (such as "parallel") should not be interpreted in a strict sense. For example, "parallel" may deviate slightly from the strict meaning of "parallel." Geometric terms may include, for example, tolerances, errors, etc. in design, operation, manufacturing, etc.

[0022] The stoichiometric composition formula is merely a representative example of a compound. A compound may have a non-stoichiometric composition. For example, "LiCoO2" is not limited to a composition ratio of "Li / Co / O=1 / 1 / 2" and may contain Li, Co, and O in any composition ratio. Furthermore, doping or substitution with trace elements may also be permitted.

[0023] <All-solid-state battery> FIG. 1 is a conceptual diagram of an all-solid-state battery according to this embodiment. FIG. 1 conceptually shows a cross section parallel to the thickness direction (Z-axis direction) of the battery 100. The battery 100 includes a power generating element 50. The battery 100 may include, for example, an exterior body (not shown). The exterior body may house the power generating element 50. The exterior body may be, for example, a pouch made of a metal foil laminate film or a metal case. The battery 100 may include a single power generating element 50 or multiple power generating elements 50. The multiple power generating elements 50 may form, for example, a series circuit or a parallel circuit.

[0024] The power generating element 50 includes a positive electrode layer 10, a separator layer 30, and a negative electrode layer 20. The separator layer 30 is disposed between the positive electrode layer 10 and the negative electrode layer 20. The separator layer 30 separates the positive electrode layer 10 from the negative electrode layer 20. The power generating element 50 may include a positive electrode current collector 11 and a negative electrode current collector 21. The positive electrode current collector 11 is in contact with the positive electrode layer 10. The negative electrode current collector 21 is in contact with the negative electrode layer 20. The positive electrode current collector 11 and the negative electrode current collector 21 may each independently have a thickness of, for example, 5 to 50 μm. The positive electrode current collector 11 and the negative electrode current collector 21 may each independently include, for example, an Al foil, an Al alloy foil, a Cu foil, a Ni foil, or a stainless steel foil.

[0025] 《Side end face》 The power generating element 50 has a flush structure in a discharged state. The positive electrode layer is flush with the negative electrode layer at the side end surface in the X-axis direction and the side end surface in the Y-axis direction in Fig. 1. That is, the relationship of the following formula (1) is satisfied. 0.99≦S a0 / S c0 ≦1.01 (1) S a0 indicates the area of ​​the negative electrode layer 20 when the SOC is 0%. c0 indicates the area of ​​the positive electrode layer 10 when the SOC is 0%. a0 / S c0 " may be, for example, 1.00 or more or 1.00 or less.a0 / S c0 If " is less than 0.99 or exceeds 1.01, it is considered that there is a step on the side end surface of the power generating element 50.

[0026] The positive electrode layer 10 and the negative electrode layer 20 may have any planar shape. The "planar shape" refers to the shape in the XY plane. For example, the planar shape of the positive electrode layer 10 and the negative electrode layer 20 may be rectangular.

[0027] Upon charging, the area of ​​the negative electrode layer 20 may not change or may expand slightly. That is, the relationship of the following formula (2) is satisfied. 1.00≦S a1 / S a0 ≦1.13 (2) S a0 indicates the area of ​​the negative electrode layer 20 when the SOC is 0%. a1 indicates the area of ​​the negative electrode layer 20 when the SOC is 100%. a1 / S a0 " may be, for example, 1.06 or more, or 1.10 or more. a1 / S a0 " may be, for example, 1.10 or less, or 1.06 or less. a1 / S a0 " can be adjusted by, for example, the type of negative electrode active material, the composite composition, the composite density, the thickness of the negative electrode layer 20, and the like.

[0028] Upon charging, the area of ​​the positive electrode layer 10 may expand or contract slightly, that is, the relationship of the following formula (3) is satisfied. 0.93≦S c1 / S c0 ≦1.02 (3) S c0 indicates the area of ​​the positive electrode layer 10 when the SOC is 0%. c1indicates the area of ​​the positive electrode layer 10 when the SOC is 100%. When the above formulas (2) and (3) are satisfied, a reduction in the amount of self-discharge is expected. During charging, the timing and direction of the area change between the positive electrode layer 10 and the negative electrode layer 20 do not match, which is thought to reduce the chance of contact between the positive electrode layer 10 and the negative electrode layer 20. For example, "1.00 c1 / S c0 When the relationship of " is satisfied, "S a1 / S a0 c1 / S c0 " may be satisfied. c1 / S c0 " can be adjusted by, for example, the type of positive electrode active material, the composite composition, the composite density, the thickness of the positive electrode layer 10, and the like.

[0029] For example, the relationship of the following formula (3)' may further be satisfied. 0.93≦S c1 / S c0 <1.00 (3)' By satisfying the above formula (3)', the area change of the positive electrode layer 10 and the area change of the negative electrode layer 20 can be in opposite directions during charging. Therefore, a reduction in the amount of self-discharge is expected. c1 / S c0 " may be, for example, 0.98 or less, or 0.96 or less.

[0030] For example, the relationship of the following formula (4) may further be satisfied. 0.98≦S a1 / S c1 ≦1.10 (4) By satisfying the relationship of the above formula (4), it is expected that the self-discharge amount will be reduced. This is thought to be because the distortion of the power generating element 50 during charging will be reduced. a1 / S c1 " may be, for example, 1.02 or more. a1 / S c1 " may be, for example, 1.08 or less, or 1.04 or less.

[0031] ​​It is believed that there is substantially no change in the area of ​​separator layer 30 during charging. In the flush structure, for example, the relationships of the following formulas (5) and (6) may be satisfied. 0.99≦S a0 / S s ≦1.01 (5) 0.99≦S c0 / S s ≦1.01 (6) S s indicates the area of ​​the separator layer 30.

[0032] <Positive electrode layer> The positive electrode layer 10 may have a thickness of, for example, 10 to 500 μm or 50 to 200 μm. The positive electrode layer 10 may have a density of, for example, 2 to 5 g / cm 3 or 2-4g / cm 3 The positive electrode layer 10 may have a density (composite density) of 1000 to 10 ...

[0033] (Cathode active material) The positive electrode active material may be, for example, in a particulate form. The positive electrode active material may have, for example, a D50 of 1 to 30 μm. "D50" refers to the particle size at which the cumulative frequency of particles with smaller diameters reaches 50% in a volume-based particle size distribution. D50 can be measured using a laser diffraction particle size distribution analyzer. The positive electrode active material induces a positive electrode reaction. The positive electrode active material may contain, for example, at least one selected from the group consisting of lithium cobalt composite oxide (LCO), spinel-type lithium nickel manganese composite oxide (NiMn spinel), NCM, NCA, and LFP.

[0034] NCAs can be, for example, compounds of the general formula: Li 1-a Ni x Co y Al zIt may have a composition represented by O2(0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1, -0.5 ≤ a ≤ 0.5). x may be, for example, 0.7 to 0.9. z may be, for example, 0.03 to 0.15. NCA may be, for example, LiNi 0.8 Co 0.15 Al 0.05 O2 and the like.

[0035] NCM may be, for example, of the general formula: Li 1-a Ni x Co y Mn z It may have a composition represented by O2(0 < x < 1, 0 < y < 1, 0 < z < 1, x + y + z = 1, -0.5 ≤ a ≤ 0.5). x may be, for example, 0.3 to 0.9. NCM may be, for example, LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, LiNi 0.5 Co 0.2 Mn 0.3 O2, LiNi 0.6 Co 0.3 Mn 0.1 O2, LiNi 0.7 Co 0.2 Mn 0.1 O2, LiNi 0.8 Co 0.1 Mn 0.1 O2 and the like.

[0036] LFP may have a composition such as LiFePO4, for example. NiMn spinel may have a composition such as LiNi 0.5 Mn 1.5 O4 and the like. LCO may have a composition such as LiCoO2, for example. The positive electrode active material may be coated with an oxide solid electrolyte, for example. The oxide solid electrolyte may contain, for example, LiNbO3, Li3PO4, and the like.

[0037] During charging, due to the contraction of the positive electrode active material, "S c1 / S c0For example, NCM, NCA, and LFP may shrink during charging. The volume change rate (shrinkage rate) of the positive electrode active material may be, for example, -7 to -2%, or -7 to -4%. The volume change rate of the electrode active material is calculated by the following formula. "Electrode active material" refers to a positive electrode active material or a negative electrode active material. α={(v1 / v0)-1}×100 α [%] indicates the volume change rate. v0 is the specific volume [m 3 / kg] is shown. v1 indicates the specific volume of the electrode active material when the SOC is 100%.

[0038] (solid electrolyte) The solid electrolyte can form an ion conduction path in the electrode layer. "Electrode layer" is a general term for the positive electrode layer and the negative electrode layer. The solid electrolyte may be, for example, particulate. The solid electrolyte may have a D50 of, for example, 0.1 to 3 μm. The D50 of the solid electrolyte may be, for example, 1 μm or less, or 0.5 μm or less. The electrode layer may contain, for example, at least one selected from the group consisting of a sulfide solid electrolyte, an oxide solid electrolyte, a nitride solid electrolyte, a halide solid electrolyte, and a hydride solid electrolyte. The sulfide solid electrolyte can have high ion conductivity. Examples of sulfide solid electrolytes include LiI-LiBr-Li3PS4, Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2O-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-GeS2-P2S5, Li2S-P2S5, Li4P2S6, and Li7P3S 11 and Li3PS4. For example, "LiI-LiBr-Li3PS4" refers to a material synthesized by mixing LiI, LiBr, and Li3PS4 in a given molar ratio (ratio of amounts of substances). The sulfide solid electrolyte may be, for example, a glass ceramic type or an argyrodite type.

[0039] (Conductive material) The conductive material can form an electron conduction path in the electrode layer, and may include, for example, at least one selected from the group consisting of acetylene black (AB), vapor-grown carbon fiber (VGCF), carbon nanotube (CNT), and graphene flake (GF).

[0040] (binder) The binder can bind solid materials together, and may include, for example, at least one selected from the group consisting of styrene butadiene rubber (SBR), acrylate butadiene rubber (ABR), polyvinylidene fluoride (PVDF), and vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP).

[0041] <<Negative electrode layer>> The negative electrode layer 20 may have a thickness of, for example, 10 to 500 μm or 50 to 200 μm. 3 or 1-2g / cm 3 The negative electrode layer 20 may have a density of 0.01 to 0.01 mm. The negative electrode layer 20 includes a negative electrode active material. The negative electrode layer 20 may further include a solid electrolyte, a conductive material, a binder, and the like. The negative electrode layer 20 may include, for example, 1 to 10% by mass of a binder, 0 to 10% by mass of a conductive material, 1 to 30% by mass of a solid electrolyte, and the remainder being a negative electrode active material. The solid electrolyte, the conductive material, and the binder may be selected arbitrarily from the group of materials described in the above section "Positive Electrode Layer." The various materials, such as the solid electrolyte, may be the same or different between the negative electrode layer 20 and the positive electrode layer 10.

[0042] (Negative electrode active material) The negative electrode active material may be, for example, particulate. The negative electrode active material may have, for example, a D50 of 1 to 30 μm. The negative electrode active material causes a negative electrode reaction. The negative electrode active material may contain, for example, at least one selected from the group consisting of LTO, TNO, graphite, and hard carbon. LTO is, for example, Li4Ti5O 12The TNO may have a composition such as TiNb2O7. LTO is expected to have almost no volume change during charging. TNO, graphite, and hard carbon tend to have a low expansion rate during charging. The low expansion rate of the negative electrode active material during charging allows for the "S a1 / S a0 The volume change rate (expansion rate) of the negative electrode active material may be, for example, 0 to +13%, 0 to +10%, or 0 to +6%.

[0043] <<Separator layer>> The separator layer 30 may have a thickness of, for example, 1 to 100 μm. The separator layer 30 is also referred to as a "solid electrolyte layer." The separator layer 30 may contain a solid electrolyte, a binder, and the like. The solid electrolyte and binder may be selected from the group of materials described above in the "Positive Electrode Layer" section, for example. The solid electrolyte and binder may be the same or different between the separator layer and the electrode layer. [Example]

[0044] <Test Battery Manufacturing> No. 1 (Preparation of negative electrode paste) Negative electrode active material (Li4Ti5O 12 The sintered body, a conductive material (carbon material), a binder, and 1.6 parts by mass of a dispersion medium (butyl butyrate) were mixed for 30 minutes using an ultrasonic homogenizer (model "UH-50" manufactured by SMT Corporation; the same applies hereinafter) to form a slurry. The slurry and the solid electrolyte were then mixed for 30 minutes using the ultrasonic homogenizer to form a negative electrode paste.

[0045] (Preparation of positive electrode paste) Cathode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3The surface of the cathode active material (LiNbO2) was coated with an oxide solid electrolyte (LiNbO3). After the coating process, 2 parts by mass of the cathode active material, 0.048 parts by mass of a conductive material (VGCF), 0.407 parts by mass of a solid electrolyte, 0.016 parts by mass of a binder, and 1.3 parts by mass of a dispersion medium (butyl butyrate) were mixed using an ultrasonic homogenizer to form a cathode paste.

[0046] (Preparation of separator paste) A binder solution was prepared. The binder solution contained 5% by mass of solute (butadiene-based rubber) and the remainder of the solvent (heptane). In a polypropylene (PP) container, the dispersion medium (heptane), binder solution, and solid electrolyte (LiI-LiBr-Li3PS4-based glass ceramics, D50 = 2.5 μm) were mixed for 30 seconds using an ultrasonic homogenizer. The PP container was then placed in a shaker. The PP container was shaken for 3 minutes in the shaker to form a separator paste.

[0047] (Formation of electrode layer) The positive electrode paste was applied to the surface of the positive electrode current collector (Al foil) using a blade applicator to form a coating film, which was then dried on a hot plate at 100°C for 30 minutes to form a positive electrode layer.

[0048] The negative electrode paste was applied to the surface of the negative electrode current collector (Al foil) using a blade applicator to form a coating film. The coating film was dried for 30 minutes on a hot plate at 100°C to form a negative electrode layer. The coating weight [g / cm 2 The "opposite capacity ratio" is the charge capacity of the positive electrode layer per unit area [mAh / cm 2 The charge capacity of the positive electrode layer is the ratio of the charge capacity of the negative electrode layer per unit area to the charge capacity of the positive electrode layer. 1 / 3 Co 1 / 3 Mn 1 / 3 The specific charge capacity of O2 was calculated as 185 mAh / g.

[0049] (Formation of separator layer) The positive electrode layer was subjected to press working. After press working, a separator paste was applied to the surface of the positive electrode layer using a die coater to form a coating film. The coating film was dried for 30 minutes on a hot plate at 100°C to form a first separator layer. Roll press working (2 t / cm 2 , room temperature) was applied to the first separator layer and the positive electrode layer to form a first unit.

[0050] The negative electrode layer was subjected to press working. After press working, a separator paste was applied to the surface of the negative electrode layer using a die coater to form a coating film. The coating film was dried for 30 minutes on a hot plate at 100°C to form a second separator layer. Roll press working (2 t / cm 2 , room temperature) was applied to the second separator layer and the negative electrode layer to form a second unit.

[0051] The third separator layer was formed by applying a separator paste to the surface of the substrate. The third separator layer was pressed onto the surface of the first separator layer by transfer processing. The first unit and the second unit were superimposed so that the third separator layer was bonded to the second separator layer, thereby forming a laminate. Press processing (2t / cm 2 The laminate was subjected to a annealing treatment (heat treatment at 130°C) to form a power generating element. The power generating element included a positive electrode layer, a separator layer, and a negative electrode layer. The separator layer was formed by integrating the first to third separator layers.

[0052] The power generating element was processed into a disk shape by punching. After processing, the power generating element had a diameter of 11.28 mm. The side end surfaces (outer peripheral surfaces) of the power generating element were flush. A pouch made of Al laminated film was prepared as the exterior body. The power generating element was vacuum sealed in the exterior body to produce a test battery. A restraining member was attached to the test battery so that a pressure of 5 MPa was applied to the power generating element.

[0053] No.2-12 Figure 2 is a table showing the configurations and self-discharge rates of test batteries. Test batteries were fabricated using the same procedures as No. 1, except that the various materials listed in the table were used as the negative and positive electrode active materials.

[0054] No. 13-15 In Nos. 13 to 15, punching was not performed, and power generating elements having steps on the side end faces were manufactured (see FIG. 2).

[0055] <Self-discharge measurement> The SOC of the test battery was adjusted to 100% using constant current-constant voltage charging (current during constant current charging = 1C, voltage during constant voltage charging = 2.95V, cut current = 0.01C). "C" is the symbol indicating the time rate of current. 1C indicates the time rate at which the rated capacity of the test battery is discharged in 1 hour. The test battery was stored at room temperature for 72 hours. The self-discharge amount was calculated using the following formula. ΔV=OCV1-OCV2 ΔV: Self-discharge amount [mV / day] OCV1: OCV (Open Circuit Voltage) after 48 hours OCV2: OCV after 72 hours

[0056] <Result> Nos. 13 to 15 have steps on the side end surfaces of the power generating element. Nos. 13 to 15 have low self-discharge amounts (see Figure 2). However, there is thought to be room for improvement in material efficiency, etc.

[0057] No. 11 differs from No. 14 in that the power generating element has a flush structure. No. 11 has a larger self-discharge amount than No. 14 (see Figure 2). This is thought to be because the positive electrode layer and the negative electrode layer may come into contact with each other during charging.

[0058] Nos. 1 to 10 have a flush structure for the power-generating element. Despite this, Nos. 1 to 10 tend to have small self-discharge amounts (see Figure 2). Nos. 1 to 10 satisfy the relationships of the above formulas (1) to (3). During charging, the timing and direction of area change between the positive electrode layer and the negative electrode layer do not match, which is thought to reduce the chance of contact between the positive electrode layer and the negative electrode layer.

[0059] Comparing No. 9 and No. 10, it is believed that satisfying the relationship of the above formula (3)' can reduce the self-discharge amount. This is thought to be because the area change of the positive electrode layer and the area change of the negative electrode layer can be in opposite directions during charging. [Explanation of symbols]

[0060] 10 positive electrode layer, 11 positive electrode current collector, 20 negative electrode layer, 21 negative electrode current collector, 30 separator layer, 50 power generating element, 100 battery.

Claims

1. a positive electrode layer, a separator layer, and a negative electrode layer; the separator layer is disposed between the positive electrode layer and the negative electrode layer; the negative electrode layer contains a negative electrode active material, the negative electrode active material is at least one selected from the group consisting of lithium-titanium composite oxide, titanium-niobium composite oxide, graphite, and hard carbon; Equations (1) to (3): 0.99≦S a0 / S c0 ≦1.01 (1) 1.00≦S a1 / S a0 ≦1.13 (2) 0.93≦S c1 / S c0 ≦1.02 (3) Fulfilling the relationship, In the formulas (1) to (3), S c0 indicates the area of ​​the positive electrode layer when the SOC is 0%, S c1 indicates the area of ​​the positive electrode layer when the SOC is 100%, S a0 indicates the area of ​​the negative electrode layer when the SOC is 0%, S a1 indicates the area of ​​the negative electrode layer when the SOC is 100%; All-solid-state battery.

2. Formula (3)': 0.93≦S c1 / S c0 <1.00 (3)’ Satisfy the relationship of The all-solid-state battery according to claim 1 .

3. Formulas (5) and (6): 0.99≦S a0 / S s ≦1.01 (5) 0.99≦S c0 / S s ≦1.01 (6) Further satisfying the relationship In the formulas (5) and (6), S s represents the area of ​​the separator layer; The all-solid-state battery according to claim 1 .

4. the positive electrode layer contains a positive electrode active material, the positive electrode active material is at least one selected from the group consisting of lithium nickel cobalt manganese composite oxide, lithium nickel cobalt aluminum composite oxide, and lithium iron phosphate; The all-solid-state battery according to any one of claims 1 to 3.

5. A power generating element is included, the power generating element includes a positive electrode layer, a separator layer, and a negative electrode layer in this order; The side end surfaces of the power generating element are configured to be flush in a discharge state, the positive electrode layer contains a positive electrode active material, the separator layer is disposed between the positive electrode layer and the negative electrode layer; the negative electrode layer contains a negative electrode active material, Formulas (1), (2), (3)′, (5) and (6): 0.99≦S a0 / S c0 ≦1.01 (1) 1.00≦S a1 / S a0 ≦1.13 (2) 0.93≦S c1 / S c0 <1.00 (3)’ 0.99≦S a0 / S s ≦1.01 (5) 0.99≦S c0 / S s ≦1.01 (6) Fulfilling the relationship, In the formulas (1), (2), (3)′, (5) and (6), S c0 indicates the area of ​​the positive electrode layer when the SOC is 0%, S c1 indicates the area of ​​the positive electrode layer when the SOC is 100%, S a0 indicates the area of ​​the negative electrode layer when the SOC is 0%, S a1 indicates the area of ​​the negative electrode layer when the SOC is 100%, S s represents the area of ​​the separator layer; All-solid-state battery.

6. The positive electrode active material is at least one selected from the group consisting of lithium nickel cobalt manganese composite oxide, lithium nickel cobalt aluminum composite oxide, and lithium iron phosphate. The all-solid-state battery according to claim 5 .

7. The negative electrode active material is at least one selected from the group consisting of lithium titanium composite oxide, titanium niobium composite oxide, graphite, and hard carbon. The all-solid-state battery according to claim 5 or 6.

8. 1.06≦S a1 / S a0 ≦1.13 Satisfy the relationship of The all-solid-state battery according to claim 5 .

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