Non-aqueous battery

Abstract

To mitigate current concentration in the vicinity of a terminal in a lateral terminal structure.SOLUTION: A non-aqueous battery includes a case, an electrode body, and an electrolyte. The case has a rectangular parallelepiped shape. The case has a width direction, a height direction, and a thickness direction. The case includes a first side wall and a second side wall. The second side wall faces the first side wall. Each of the first side wall and the second side wall is orthogonal to the width direction. A cathode terminal and an anode terminal are provided to the first side wall. The electrode body is a wound type. The winding axis of the electrode body is parallel to the width direction. The electrode body includes a first end and a second end. The first end faces the first side wall. A relationship R1 / R2>1 is satisfied. R1 denotes electrode resistance at the first end, and R2 denotes electrode resistance at the second end.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to non-aqueous batteries. [Background technology]

[0002] JP2014-099365A discloses an electrode winding body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-099365 A Summary of the Invention [Problem to be solved by the invention]

[0004] A "horizontal terminal structure" is being considered. In the horizontal terminal structure, the case is rectangular (rectangular). The case (rectangular) has a width direction, a height direction, and a thickness direction. Of the six faces of the rectangular parallelepiped, the two faces perpendicular to the width direction are considered to be sides. The wall that includes the side is the side wall. Both the positive and negative terminals are arranged on one of the two side walls. The electrode body is stored in the case so that the winding axis of the electrode body is parallel to the width direction. In the horizontal terminal structure, current concentration occurs in the part of the electrode body near the terminal, which can cause localized deterioration.

[0005] An object of the present disclosure is to alleviate current concentration near the terminal in a lateral terminal structure. [Means for solving the problem]

[0006] 1. The non-aqueous battery includes a case, an electrode body, and an electrolyte. The case houses the electrode body and the electrolyte. The case has a rectangular parallelepiped outer shape. The case has a width direction, a height direction, and a thickness direction. The width direction, the height direction, and the thickness direction are mutually perpendicular. The case includes a first side wall and a second side wall. The second side wall faces the first side wall. Each of the first side wall and the second side wall is perpendicular to the width direction. A positive electrode terminal and a negative electrode terminal are provided on the first side wall. The electrode body is of a wound type. The winding axis of the electrode body is parallel to the width direction. The electrode body includes a first end and a second end. The first end is disposed at one end in the width direction. The second end is disposed at the other end in the width direction. The first end faces the first side wall. The non-aqueous battery satisfies the relationship of the following formula (1). R1 / R2>1 (1) In the above formula (1), R1 represents the electrode resistance at the first end, and R2 represents the electrode resistance at the second end.

[0007] By reducing the electrode resistance on the opposite side (second end) compared to the vicinity of the terminal (first end), it is expected that current concentration in the vicinity of the terminal will be alleviated.

[0008] 2. The nonaqueous battery according to the above item "1" may have the following configuration, for example: The case has an aspect ratio of 2.9 or more. The aspect ratio indicates the ratio of the width dimension to the height dimension.

[0009] Conventionally, in a lateral terminal structure, when the aspect ratio is 2.9 or more, current concentration in the vicinity of the terminal is significant. The above technology "1" is suitable for when the aspect ratio is 2.9 or more.

[0010] 3. The nonaqueous battery according to the above item "1" or "2" may, for example, include the following configuration: In the width direction, the electrode assembly has a dimension of 20 to 80 cm.

[0011] 4. The nonaqueous battery according to any one of the above items "1" to "3" may include, for example, the following configuration: A liquid injection port is provided in the second side wall. The electrolyte contains a component that can reduce the electrode resistance.

[0012] The electrolyte may contain various additives. The electrolyte may contain, for example, a component that can reduce the electrode resistance. For example, when a liquid inlet is provided on the first side wall, the additive tends to have a greater effect at the first end close to the liquid inlet. This is thought to be because the electrolyte is likely to stagnate near the liquid inlet when the electrolyte is injected. The reduction in electrode resistance at the first end may promote current concentration at the first end. On the other hand, the liquid inlet is disposed on the second side wall, and it is expected that the additive will have a greater effect at the second end. As a result, it is expected that the value of "R1 / R2" in "1" above will increase. That is, it is expected that the current concentration at the first end will be alleviated.

[0013] 5. The nonaqueous battery described in "4" above may include, for example, the following configuration: The component capable of reducing the electrode resistance includes lithium bis(oxalate)borate (LiBOB).

[0014] 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 embodiment") will be described. However, the present embodiment and the present embodiment do not limit the technical scope of the present disclosure. The present embodiment and the present embodiment are illustrative in all respects. The present embodiment and the present embodiment are non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the description of the claims. For example, it is also intended from the beginning that any configuration may be extracted from the present embodiment and arbitrarily combined. [Brief description of the drawings]

[0015] [Figure 1] 1 is a schematic cross-sectional view showing an example of a nonaqueous battery according to the present embodiment. [Diagram 2] FIG. 4 is a schematic diagram showing an example of a case in the present embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing an example of an electrode body in the present embodiment. [Figure 4] FIG. 2 is a schematic plan view showing an example of an electrode and a separator in the present embodiment. [Diagram 5] 13 is a table showing experimental results. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] <Terminology> The "non-aqueous battery" includes an organic electrolyte. The non-aqueous battery may be, for example, a lithium ion battery.

[0017] The "electrode resistance" may be expressed as local resistance. The electrode resistance indicates a value measured by the following method. The SOC (State Of Charge) of the non-aqueous battery is adjusted to 0%. The non-aqueous battery is disassembled to recover the electrode body. The electrode body is disassembled. A positive electrode piece and a negative electrode piece are each collected from the target portion (first end, second end) of the electrode body by punching. The positive electrode piece and the negative electrode piece are both disk-shaped. The positive electrode piece and the negative electrode piece each have a diameter of 10 mm. A laminate is formed by stacking the positive electrode piece, the separator, and the negative electrode piece. A coin cell is produced by sealing the laminate and the electrolyte in a coin-shaped exterior body. The internal resistance of the coin cell is the electrode resistance. The internal resistance is measured by a resistance measuring device. A resistance measuring device having a measurement range suitable for the internal resistance of the coin cell is selected. The separator of the coin cell may be, for example, a product of the same specifications as the separator of the electrode body. The electrolyte of the coin cell has any composition. For example, it may have the following composition: Solvent: EC / EMC / DMC=1 / 1 / 1 (volume ratio) Supporting electrolyte: LiPF6 (1mol / L) Additives: None The official names of abbreviations such as "EC" will be given later.

[0018] "Width" refers to the dimension in the width direction. "Height" refers to the dimension in the height direction. "Thickness" refers to the dimension in the thickness direction.

[0019] Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and the like. For example, "parallel" may deviate slightly from the strict meaning of "parallel." Geometric terms may include, for example, tolerances, errors, and the like in design, work, and manufacturing. The dimensional relationships in each figure may not match the actual dimensional relationships. For example, the dimensional relationships in each figure may be changed to help the reader understand. For example, the length, width, thickness, and the like may be changed. Some configurations may be omitted.

[0020] Numerical ranges such as "m to n%" include upper and lower limits unless otherwise specified. That is, "m to n%" indicates a numerical range of "m% or more and n% or less". "m% or more and n% or less" includes "more than m% and less than n%". "More than" and "less than" are represented by an inequality sign with an equal sign "≦". "More than" and "less than" are represented by an inequality sign without an equal sign "<". A numerical value arbitrarily selected from within the numerical range may be set as a new upper or lower limit. For example, a new numerical range may be set by arbitrarily combining a numerical value within the numerical range with a numerical value described in another part of this specification, in a table, in a figure, or the like.

[0021] <Non-aqueous batteries> 1 is a schematic cross-sectional view showing an example of a nonaqueous battery in this embodiment. Battery 1 is a nonaqueous battery. Battery 1 includes a case 200, an electrode assembly 100, and an electrolyte (not shown). Case 200 houses electrode assembly 100 and the electrolyte.

[0022] <Case> FIG. 2 is a schematic diagram showing an example of a case in this embodiment. The case 200 is rectangular. That is, the case 200 has a rectangular parallelepiped outer shape. The corners of the case 200 may be rounded. The case 200 has a width (W) direction, a height (H) direction, and a thickness (T) direction. The W direction, the H direction, and the T direction are mutually perpendicular. The H direction may be parallel to the vertical direction, for example. The W direction may be parallel to the horizontal direction, for example. The T direction may be parallel to the horizontal direction, for example. The width may be larger than the height and thickness, for example. The thickness may be smaller than the width and height, for example. For example, the relationship of "thickness≦height<width" may be satisfied. The case 200 may have an aspect ratio (width / height) of, for example, 2.9 or more. The aspect ratio of the case 200 may be, for example, 5 or more. The aspect ratio of the case 200 may be, for example, 2.9 to 5.

[0023] The case 200 may be made of, for example, a metal. The case 200 may include, for example, pure Al, an Al alloy, or the like. The case 200 includes a first bottom wall 211, a second bottom wall 212, a first main wall 221, a second main wall 222, a first side wall 231, and a second side wall 232. Each of the first bottom wall 211 and the second bottom wall 212 is perpendicular to the H direction. The first bottom wall 211 faces the second bottom wall 212. Each of the first main wall 221 and the second main wall 222 is perpendicular to the T direction. The first main wall 221 faces the second main wall 222. The first main wall 221 (second main wall 222) has a larger area than the first bottom wall 211 (second bottom wall 212) and the first side wall 231 (second side wall 232).

[0024] Each of the first side wall 231 and the second side wall 232 is perpendicular to the W direction. The first side wall 231 faces the second side wall 232. That is, the first side wall 231 is disposed at one end in the W direction. The second side wall 232 is disposed at the other end in the W direction. A positive electrode terminal 251 and a negative electrode terminal 252 are provided on the first side wall 231.

[0025] For example, a liquid inlet 261 may be provided in the second side wall 232. An electrolyte can be injected into the case 200 through the liquid inlet 261. The liquid inlet 261 can be closed by, for example, a sealing plug 262 (see FIG. 1).

[0026] <Electrode body> FIG. 3 is a schematic diagram showing an example of an electrode body in this embodiment. FIG. 4 is a schematic plan view showing an example of an electrode and a separator in this embodiment. The electrode body 100 is a wound type. The electrode body 100 includes a positive electrode 110, a negative electrode 120, and a separator 130. The positive electrode 110, the negative electrode 120, and the separator 130 are all strip-shaped sheets. The electrode body 100 may include two or more separators. For example, the positive electrode 110, the separator 130, the negative electrode 120, and the separator 130 are stacked in this order to form a laminate. The electrode body 100 may be formed by spirally winding the laminate around the winding axis A. The electrode body 100 may be wound either clockwise or counterclockwise around the winding axis A. After winding, the electrode body 100 may be formed into a flat shape. In the case 200, the winding axis A of the electrode body 100 is parallel to the W direction.

[0027] The electrode body 100 may have an aspect ratio of, for example, 2.9 or more. The aspect ratio of the electrode body 100 may be, for example, 5 or more. The aspect ratio of the electrode body 100 may be, for example, from 2.9 to 5. The electrode body 100 may have a width of, for example, from 20 to 80 cm.

[0028] The electrode assembly 100 may include a positive electrode tab 113 and a negative electrode tab 123. The positive electrode tab 113 is connected to a positive electrode terminal 251. The negative electrode tab 123 is connected to a negative electrode terminal 252 (see FIG. 1).

[0029] <First end, second end> The electrode body 100 includes a first end 101 and a second end 102. At the first end 101 and the second end 102, the side surfaces of the electrode are exposed. The first end 101 and the second end 102 may be referred to as, for example, a "first open end" and a "second open end".

[0030] The first end 101 is disposed at one end in the W direction. The first end 101 faces the first side wall 231. The first end 101 is adjacent to the positive electrode terminal 251 and the negative electrode terminal 252. The positive electrode tab 113 and the negative electrode tab 123 may be disposed at the first end 101. The second end 102 is disposed at the other end in the W direction. The second end 102 is disposed on the opposite side of the first end 101 in the W direction. The second end 102 faces the second side wall 232. The second end 102 may face the liquid inlet 261.

[0031] The first end 101 may be, for example, in the W direction, within a range of up to 5 cm inward from the end of the electrode body 100. The second end 102 may be, for example, in the W direction, within a range of up to 5 cm inward from the end of the electrode body 100.

[0032] The first end 101 has a first electrode resistance (R1). The second end 102 has a second electrode resistance (R2). The resistance ratio (R1 / R2) is greater than 1. That is, the relationship of the following formula (1) is satisfied. R1 / R2>1 (1) A resistance ratio exceeding 1 can alleviate current concentration at the first end 101. The resistance ratio may be, for example, any of 1.01 or more, 1.05 or more, 1.09 or more, 1.10 or more, or 1.12 or more. The resistance ratio may be, for example, any of 1.20 or less, 1.12 or less, 1.10 or less, or 1.09 or less.

[0033] <Positive electrode> The two-dot chain line in FIG. 4 indicates a corner portion of the electrode body 100. The positive electrode 110 includes a positive electrode collector 111 and a positive electrode active material layer 112. The positive electrode collector 111 may include, for example, Al foil or the like. A part of the positive electrode collector 111 may be processed into a positive electrode tab 113. The positive electrode tab 113 may be joined to the positive electrode collector 111. The positive electrode tab 113 is disposed on one side in the W direction. There may be multiple positive electrode tabs 113. The positive electrode 110 is wound along the length (L) direction. The multiple positive electrode tabs 113 are disposed so as to overlap in the T direction after winding (electrode body 100).

[0034] The positive electrode active material layer 112 is disposed on the surface of the positive electrode current collector 111. The positive electrode active material layer 112 includes a positive electrode active material. The positive electrode active material may include at least one selected from the group consisting of LiCoO2, LiNiO2, LiMnO2, LiMn2O4, Li(NiCoMn)O2, Li(NiCoAl)O2, and LiFePO4. For example, "(NiCoMn)" in "Li(NiCoMn)O2" indicates that the sum of the composition ratios in parentheses is 1. As long as the sum is 1, the amount of each component is arbitrary. Li(NiCoMn)O2 is, for example, Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O2, Li(Ni 0.5 Co 0.2 Mn 0.3 )O2, Li(Ni 0.8 Co 0.1 Mn 0.1 ) O2, etc.

[0035] The positive electrode active material layer 112 may further include a conductive material and a binder. The conductive material may include at least one selected from the group consisting of carbon black, vapor-grown carbon fiber, carbon nanotubes, and graphene flakes. The amount of the conductive material may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The same applies to the conductive material in the negative electrode active material layer 122 (described later).

[0036] The binder may include at least one selected from the group consisting of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyimide (PI), polyamide-imide (PAI), and polyacrylic acid (PAA). The amount of the binder may be, for example, 0.1 to 10 parts by mass with respect to 100 parts by mass of the positive electrode active material. The same applies to the binder in the negative electrode active material layer 122 (described later).

[0037] <Negative electrode> The negative electrode 120 includes a negative electrode current collector 121 and a negative electrode active material layer 122. The negative electrode current collector 121 may include, for example, Cu foil or the like. A part of the negative electrode current collector 121 may be processed into a negative electrode tab 123. The negative electrode tab 123 may be joined to the negative electrode current collector 121. The negative electrode tab 123 is disposed on one side in the W direction. There may be a plurality of negative electrode tabs 123. The negative electrode 120 is wound along the L direction. The plurality of negative electrode tabs 123 are disposed in the electrode body 100 so as to overlap in the T direction. The negative electrode tab 123 and the positive electrode tab 113 are disposed so that the negative electrode tab 123 is separated from the positive electrode tab 113 in the H direction of the electrode body 100.

[0038] The negative electrode active material layer 122 is disposed on the surface of the negative electrode current collector 121. The negative electrode active material layer 122 includes a negative electrode active material. Examples of the negative electrode active material include graphite, soft carbon, hard carbon, silicon, silicon oxide, silicon-based alloys, tin, tin oxide, tin-based alloys, and Li4Ti5O 12 The negative electrode active material layer 122 may further include a conductive material and a binder.

[0039] <separator> The separator 130 separates the positive electrode 110 from the negative electrode 120. The separator 130 is porous. The separator 130 may be made of, for example, polyolefin. The separator 130 may have a multi-layer structure. The separator 130 may include, for example, a polypropylene (PP) layer and a polyethylene (PE) layer. The separator 130 may be formed by, for example, laminating a PP layer, a PE layer, and a PP layer in this order.

[0040] <Electrolyte> The electrolyte is a liquid electrolyte. At least a portion of the electrolyte is impregnated in the electrode body 100. The electrolyte includes a supporting electrolyte and a solvent. The concentration of the supporting electrolyte may be, for example, 0.5 to 2 mol / L. The supporting electrolyte may include at least one selected from the group consisting of LiPF6, LiBF4, and Li(FSO2)2N. The solvent may include at least one selected from the group consisting of ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), and diethyl carbonate (DEC).

[0041] The electrolyte may further contain an additive. The amount of the additive may be, for example, 0.1 to 5%, 0.1 to 3%, or 0.1 to 1% by mass fraction. The additive may have any function. The additive may contain, for example, a component that can reduce the electrode resistance. An example of the component is LiBOB. That is, the electrolyte may contain LiBOB. The additive may contain a component other than LiBOB. The additive may contain, for example, at least one selected from the group consisting of LiBOB, vinylene carbonate (VC), vinyl ethylene carbonate (VEC), 1,3-propane sultone (PS), cyclohexylbenzene (CHB), and tert-amylbenzene (TAB). EXAMPLES

[0042] <Test cell> Test cells No. 1 to No. 7 were manufactured. FIG. 5 is a table showing the experimental results. FIG. 5 shows the structure of each test cell. In FIG. 5, the "Layout" section shows a simplified positional relationship between the positive electrode terminal 251, the negative electrode terminal 252, the winding axis A, and the liquid injection port 261. The material composition is the same for each test cell. The material composition is as follows:

[0043] Cathode active material: Li(NiCoMn)O2 Negative electrode active material: natural graphite Separator: Three-layer structure (PP layer / PE layer / PP layer) Electrolyte / solvent: EC / EMC / DMC=1 / 1 / 1 (volume ratio) Electrolyte / supporting electrolyte: LiPF6 (1mol / L) Electrolyte / additive: LiBOB (0.5%, mass fraction)

[0044] <Durability test> In a temperature environment of −30° C., constant current (CC) charging and constant current-constant voltage (CCCV) discharging under the following conditions were alternately repeated 100 times.

[0045] CC charging: CC charging from 3.0V to 4.2V with a current of 1C. CCCV discharge: CC discharge with a current of 1C to 3.0V. CV charge at 3.0V.

[0046] "C" is the symbol for the hourly rate of current. At an hourly rate of 1C, the rated capacity of the battery is discharged in 1 hour.

[0047] After the durability test, the test cell was disassembled to recover the electrode body. The electrode body was further disassembled. The surface of the negative electrode included in the first end was visually observed. In the "Li Deposition" section of FIG. 5, "Yes" indicates that metallic luster was confirmed by visual observation. In the same section, "No" indicates that metallic luster was not confirmed. Furthermore, the first electrode resistance (R1) at the first end and the second electrode resistance (R2) at the second end were each measured.

[0048] <Result> No Li deposition was observed in No. 1 to No. 3. This is thought to be because the current concentration at the first end was alleviated. No. 1 to No. 3 satisfy all of the following conditions.

[0049] A positive terminal and a negative terminal are provided on the first side wall. The winding axis of the electrode body is parallel to the W direction. The relationship "R1 / R2>1" is satisfied.

[0050] Li deposition was confirmed in No. 4 to No. 7. This is believed to be due to current concentration at the first end. No. 4 to No. 7 do not meet one or more of the above conditions. [Explanation of symbols]

[0051] 1 battery (nonaqueous battery), 100 electrode body, 101 first end portion, 102 second end portion, 110 positive electrode, 111 positive electrode current collector, 112 positive electrode active material layer, 113 positive electrode tab, 120 negative electrode, 121 negative electrode current collector, 122 negative electrode active material layer, 123 negative electrode tab, 130 separator, 200 case, 211 first bottom wall, 212 second bottom wall, 221 first main wall, 222 second main wall, 231 first side wall, 232 second side wall, 251 positive electrode terminal, 252 negative electrode terminal, 261 filling port, 262 sealing plug, A winding shaft.

Claims

1. The battery includes a case, an electrode body, and an electrolyte. The case accommodates the electrode body and the electrolyte, The case has a rectangular parallelepiped outer shape, the case has a width direction, a height direction, and a thickness direction, the width direction, the height direction, and the thickness direction are perpendicular to each other, the case includes a first side wall and a second side wall; the second side wall faces the first side wall, each of the first side wall and the second side wall is perpendicular to the width direction; A positive terminal and a negative terminal are provided on the first side wall, The electrode body is a wound type, The winding axis of the electrode body is parallel to the width direction, The electrode body includes a first end and a second end, The first end portion is disposed at one end in the width direction, The second end is disposed at the other end in the width direction, the first end faces the first side wall, The relationship of formula (1) is satisfied. R1 / R2>1 (1) In the formula (1), R1 denotes the electrode resistance at the first end, and R2 denotes the electrode resistance at the second end; Non-aqueous battery.

2. The case has an aspect ratio of 2.9 or greater; and The aspect ratio indicates a ratio of a dimension in the width direction to a dimension in the height direction. The non-aqueous battery according to claim 1 .

3. In the width direction, the electrode body has a dimension of 20 to 80 cm. The non-aqueous battery according to claim 1 .

4. A liquid inlet is provided in the second side wall, and The electrolyte solution contains a component that can reduce electrode resistance. The non-aqueous battery according to any one of claims 1 to 3.

5. The component capable of reducing the electrode resistance includes lithium bis(oxalato)borate; The non-aqueous battery according to claim 4 .

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