All-solid-state battery cell

Abstract

The invention belongs to the technical field of lithium batteries, and discloses an all-solid-state battery cell, which comprises positive plates and negative plates which are sequentially connected in series and alternately arranged, any adjacent positive plate and negative plate are connected in series through n composite plates, n is an integer, and n is greater than or equal to 1; the composite pole piece comprises a first current collector, a first positive electrode material, a first negative electrode material and a first solid electrolyte, the first positive electrode material and the first solid electrolyte are sequentially coated on one surface, facing the negative pole piece, of the first current collector, and the first negative electrode material and the first solid electrolyte are sequentially coated on one surface, facing the positive pole piece, of the first current collector. The platform is high in voltage, low in capacity and high in energy; compared with a conventional battery cell, the charging and discharging current is greatly reduced, and the heat generated by the battery cell and a structural member is reduced, so that the design requirement and the heat management requirement of the structural member are greatly reduced; a larger battery cell design can be realized, and the energy density of the battery cell is further increased; the number of module / pack cells is reduced; and a single-cell high-voltage product is supported.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular relates to an all-solid-state battery cell. Background Art

[0002] Because lithium-ion batteries have a long service life and high energy density, they are often used as power batteries for vehicles. However, safety accidents related to lithium-ion batteries have occurred frequently in recent years. The main reason for the frequent safety accidents related to lithium-ion batteries is that the electrolyte used in traditional liquid lithium-ion batteries is an organic solvent. For example, most common electrolyte components are highly flammable substances, which can easily cause fires, spontaneous combustion and explosions. Solid-state batteries have significant advantages in safety, energy density and cycle life, and are the current development trend of the lithium battery industry.

[0003] Regardless of liquid / solid lithium-ion batteries, high safety, high energy density and high rate are the trends. The common NCM system single-cell platform voltage on the market is about 3.65-3.66V, and the LFP system single-cell platform voltage is 3.2-3.3V. In order to pursue high energy density, in addition to using high energy density materials, the main direction is to optimize the design of structural parts and make cells with larger capacity (larger volume / mass to achieve a larger proportion of active materials in the cell), etc. The disadvantage of large cells is that under the requirements of high rates, the thermal management of the cells is difficult (energy = capacity * voltage, the larger the capacity, the larger the charge and discharge current at the same rate (1C = capacity / 1h), and the larger the current, the greater the heat generated). Batteries are temperature-sensitive products, and thermal management is one of the current problems in the battery industry. Summary of the invention

[0004] The purpose of the present invention is to provide an all-solid-state battery cell to solve the problem of difficult thermal management of existing battery cells.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A fully solid-state battery cell comprises positive and negative electrode sheets which are sequentially connected in series and arranged alternately, and any adjacent positive and negative electrode sheets are connected in series through n composite electrode sheets, n is an integer, and n≥1; the composite electrode sheets comprise a first current collector, a first positive electrode material, a first negative electrode material and a first solid electrolyte, the first current collector has a side facing the negative electrode sheet coated with the first positive electrode material and the first solid electrolyte in sequence, and the first current collector has a side facing the positive electrode sheet coated with the first negative electrode material and the first solid electrolyte in sequence; the length of the first solid electrolyte is 0-4 mm greater than the length of the corresponding first positive electrode material or the length of the first negative electrode material, and the width of the first solid electrolyte is 0-4 mm greater than the width of the corresponding first positive electrode material or the width of the first negative electrode material.

[0007] As a preferred technical solution in the present invention, n≥2, the first solid electrolyte on one side of any two adjacent composite pole pieces close to each other is the same first solid electrolyte.

[0008] As a preferred technical solution in the present invention, the positive electrode sheet includes a second current collector, both sides of the second current collector are coated with a second positive electrode material, and the surfaces of the two second positive electrode materials are coated with a second solid electrolyte; one side of the second current collector extends to the outside of the second positive electrode materials on both sides thereof to form a positive electrode ear; the length of the second solid electrolyte is 0-4 mm larger than the length of the second positive electrode material, and the width of the second solid electrolyte is 0-4 mm larger than the width of the second positive electrode material.

[0009] As a preferred technical solution in the present invention, the first solid electrolyte and the second solid electrolyte between the positive electrode sheet and the adjacent composite electrode sheet are the same solid electrolyte.

[0010] As a preferred technical solution in the present invention, the negative electrode sheet includes a third current collector, both sides of the third current collector are coated with a second negative electrode material, and the surfaces of the two second negative electrode materials are coated with a third solid electrolyte; one side of the third current collector extends to the outside of the second negative electrode materials on both sides thereof to form a negative electrode ear; the length of the third solid electrolyte is 0-4 mm larger than the length of the second negative electrode material, and the width of the third solid electrolyte is 0-4 mm larger than the width of the second negative electrode material.

[0011] As a preferred technical solution in the present invention, the first solid electrolyte and the third solid electrolyte between the negative electrode sheet and the adjacent composite electrode sheet are the same solid electrolyte.

[0012] As a preferred technical solution of the present invention, the second positive electrode material and the second negative electrode material are both rectangular, and the area of ​​the second positive electrode material is 10-50000mm 2 The length of the second negative electrode material is 0-4 mm greater than the length of the second positive electrode material, and the width of the second negative electrode material is 0-4 mm greater than the width of the second positive electrode material.

[0013] As a preferred technical solution in the present invention, the first positive electrode material and the first negative electrode material are both rectangular, the length of the first positive electrode material is equal to the length of the second positive electrode material, the width of the first positive electrode material is equal to the width of the second positive electrode material, the length of the first negative electrode material is equal to the length of the second negative electrode material, and the width of the first negative electrode material is equal to the width of the second negative electrode material.

[0014] As a preferred technical solution in the present invention, both sides of the first current collector are coated with insulating materials, and the first positive electrode material and the first negative electrode material are located between the insulating materials on both sides of the first current collector.

[0015] As a preferred technical solution in the present invention, the width of the insulating material is 0-4 mm, the insulating material overlaps the first positive electrode material in the thickness direction by 0-1.5 mm, and the insulating material overlaps the first negative electrode material in the thickness direction by 0-1.5 mm.

[0016] The all-solid-state battery cell of the present invention has the following beneficial effects:

[0017] 1) High platform voltage, low capacity and high energy;

[0018] 2) Compared with conventional cells, the charge and discharge current is greatly reduced, and the heat generated by the cells and structural parts is reduced, thereby greatly reducing the requirements for structural part design and thermal management;

[0019] 3) Due to the above advantage 2), a larger battery cell design can be achieved, further increasing the battery cell energy density;

[0020] 4) Reduce the number of modules / pack cells (the number of strings can be reduced when the module voltage remains unchanged, and the number of parallels can be reduced when the module capacity remains unchanged), which can reduce the difficulty of module design and increase the energy density of the battery pack);

[0021] 5) Support single-cell high-voltage products;

[0022] 6) Through the solid electrolyte layer, ion conduction and electronic isolation are achieved between the positive electrode, negative electrode and composite electrode (solid electrolyte is a lithium ion conductor and an electronic insulator); the design of the composite electrode achieves electronic conduction between the positive and negative electrodes connected in series inside the battery cell and ion isolation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The schematic diagram of the structure of the all-solid-state battery cell of the present invention when n=1;

[0024] Figure 2 The schematic diagram of the structure of the all-solid-state battery cell of the present invention when n=2;

[0025] Figure 3 It is a schematic diagram of the structure of the negative electrode sheet in the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of the composite pole piece in the present invention;

[0027] Figure 5 It is a schematic diagram of the structure of the positive electrode sheet in the present invention.

[0028] In the figure: 1-positive electrode sheet; 101-second current collector; 102-second positive electrode material; 103-second solid electrolyte; 2-negative electrode sheet; 201-third current collector; 202-second negative electrode material; 203-third solid electrolyte; 3-composite electrode sheet; 301-first current collector; 302-first positive electrode material; 303-first negative electrode material; 304-first solid electrolyte; 305-insulating material. DETAILED DESCRIPTION

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in combination with the drawings and the description of the embodiments or the prior art. Obviously, the following description of the structure of the drawings is only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0030] It should be noted here that the existing solid-state batteries generally adopt the lamination process, which is composed of positive and negative electrode sheets, and the structural parts and packaging methods are the same as those of liquid batteries. The existing battery cell lamination mode is: negative electrode sheet / positive electrode sheet / negative electrode sheet / positive electrode sheet / negative electrode sheet, which are alternately stacked, and the tabs are stacked and welded to the battery cell guide structure to guide the current to the outside of the battery cell. The present invention is different from the above-mentioned prior art, and the technical solution of this application is specifically described below.

[0031] Example:

[0032] like Figure 1-Figure 5 As shown, this embodiment provides an all-solid-state battery cell, including positive electrode sheets 1 and negative electrode sheets 2 that are sequentially connected in series and alternately arranged, and any adjacent positive electrode sheets 1 and negative electrode sheets 2 are connected in series through n composite electrode sheets 3, n is an integer, and n≥1, and the actual value of n can be set according to the situation. This embodiment does not make specific restrictions, and the stacking method of this all-solid-state battery cell is: negative electrode sheet / composite electrode sheet / positive electrode sheet / composite electrode sheet / negative electrode sheet, which are alternately stacked in this way.

[0033] Furthermore, the composite electrode sheet 3 includes a first current collector 301, a first positive electrode material 302, a first negative electrode material 303 and a first solid electrolyte 304. The first current collector 301 is coated with the first positive electrode material 302 and the first solid electrolyte 304 on one side facing the negative electrode sheet 2 in sequence, and the first current collector 301 is coated with the first negative electrode material 303 and the first solid electrolyte 304 on one side facing the positive electrode sheet 1 in sequence. The first current collector 301 of the composite electrode sheet 3 realizes ion conduction and electronic isolation between the positive electrode sheets 1 and the negative electrode sheets 2 on both sides, thereby realizing internal series connection of the battery cell. The design and packaging of other structural parts of the battery cell are consistent with those of conventional batteries, and are not specifically limited. Specifically, soft packs or square hard shells such as aluminum shells can be used for packaging. It should be noted that the length of the first solid electrolyte 304 is 0-4 mm larger than the length of the corresponding first positive electrode material 302 or the length of the first negative electrode material 303, and the width of the first solid electrolyte 304 is 0-4 mm larger than the width of the corresponding first positive electrode material 302 or the width of the first negative electrode material 303, so that the first solid electrolyte 304 fully covers the corresponding first positive electrode material 302 or the first negative electrode material 303.

[0034] It should be noted that in the present application, there are many situations in which the composite electrode sheet 3 is connected in series between the positive electrode sheet 1 and the negative electrode sheet 2, such as stacking the composite electrode sheet 3 twice between the positive electrode sheet 1 and the negative electrode sheet 2, or stacking n series of composite electrode sheets 3, and welding the tab stack to the cell guide structure to guide the current to the outside of the cell. The following table 1 will show the performance comparison effect of conventional cells and the internal series cell design of the present invention.

[0035] Table 1:

[0036]

[0037] In the above Table 1, the first column of Example 1 represents various data of the existing conventional battery cells, and the eight columns of Examples 2 to 9 represent various data of the all-solid-state battery cells designed by the present invention, wherein the positive electrode materials in Examples 1 to 9 are all 9-series NCM, and the negative electrode materials are all Gr+Si. The core package thickness designs after lamination in Examples 1, 2, 5 and 8 are roughly the same (it can be understood that except for the different internal series designs, other designs are the same). Example 2, Example 5 and Example 8 are respectively designed with different numbers of positive electrode sheets 1 and negative electrode sheets 2, and then the composite electrode sheets 3 are connected in series between adjacent positive electrode sheets 1 and negative electrode sheets 2, so that Example 2 and Example 8 have the same thickness. The thickness of the core package after lamination in Example 5 and Example 8 is roughly the same as the thickness of the core package after lamination in Example 1; Example 3 and Example 4 are based on Example 2 to ensure that the number of composite electrode sheets 3 connected in series between adjacent positive electrode sheets 1 and negative electrode sheets 2 remains unchanged, and the number of positive electrode sheets 1 and negative electrode sheets 2 is adjusted; Example 6 and Example 7 are based on Example 5 to ensure that the number of composite electrode sheets 3 connected in series between adjacent positive electrode sheets 1 and negative electrode sheets 2 remains unchanged, and the number of positive electrode sheets 1 and negative electrode sheets 2 is adjusted; Example 9 is based on Example 8 to ensure that the number of composite electrode sheets 3 connected in series between adjacent positive electrode sheets 1 and negative electrode sheets 2 remains unchanged, and the number of positive electrode sheets 1 and negative electrode sheets 2 is adjusted.

[0038] It can be seen from Table 1 that the present invention has the following advantages after the composite electrode 3 is connected in series between the positive electrode 1 and the negative electrode 2:

[0039] 1) High platform voltage, low capacity and high energy;

[0040] 2) Compared with conventional batteries, the charge and discharge current is greatly reduced, and the heat generated by the battery cells and structural parts is reduced, thereby greatly reducing the requirements for structural part design and thermal management;

[0041] 3) Due to the above advantage 2), a larger battery cell design can be achieved, further increasing the battery cell energy density;

[0042] 4) Reduce the number of modules / pack cells (the number of strings can be reduced when the module voltage remains unchanged, and the number of parallels can be reduced when the module capacity remains unchanged), which can reduce the difficulty of module design and increase the energy density of the battery pack);

[0043] 5) Support single-cell high-voltage products;

[0044] 6) Through the solid electrolyte layer, ion conduction and electronic isolation are achieved between the positive electrode sheet 1, the negative electrode sheet 2 and the composite electrode sheet 3 (the solid electrolyte is a lithium ion conductor and an electronic insulator); the design of the composite electrode sheet 3 achieves electronic conduction between the positive and negative electrodes connected in series inside the battery cell and also achieves ion isolation.

[0045] It should be noted that the types of positive electrode materials (including but not limited to NCM materials, LFP materials, lithium cobalt oxide, lithium manganese oxide, etc.), negative electrode materials (including but not limited to graphite, silicon negative electrode, Li metal and alloys, etc.), solid electrolytes (including but not limited to oxides, sulfides, organic electrolytes or mixed materials) and current collectors (including but not limited to aluminum foil, nickel-plated copper foil, stainless steel foil or composite foil, etc.) of the battery cells in the present invention are not limited.

[0046] As a preferred implementation scheme in this embodiment, it needs to be further explained that, if n≥2, the first solid electrolytes 304 on one side of any two adjacent composite pole pieces 3 close to each other are the same first solid electrolyte 304 .

[0047] As a preferred implementation scheme in this embodiment, it needs to be further explained that the positive electrode sheet 1 includes a second current collector 101, both sides of the second current collector 101 are coated with a second positive electrode material 102, and the surfaces of the two second positive electrode materials 102 are coated with a second solid electrolyte 103; one side of the second current collector 101 extends to the outside of the second positive electrode materials 102 on both sides thereof to form a positive electrode ear; the length of the second solid electrolyte 103 is 0-4 mm larger than the length of the second positive electrode material 102, and the width of the second solid electrolyte 103 is 0-4 mm larger than the width of the second positive electrode material 102, so that the second solid electrolyte 103 fully covers the corresponding second positive electrode material 102.

[0048] As a preferred implementation scheme in this embodiment, it needs to be further explained that the first solid electrolyte 304 and the second solid electrolyte 103 between the positive electrode sheet 1 and the adjacent composite electrode sheet 3 are the same solid electrolyte, which can realize ion conduction and electronic isolation between the positive electrode material and the negative electrode material through the solid electrolyte, thereby realizing series connection inside the battery cell, saving costs and reducing the overall thickness.

[0049] As a preferred implementation scheme in this embodiment, it needs to be further explained that the negative electrode sheet 2 includes a third current collector 201, both sides of the third current collector 201 are coated with a second negative electrode material 202, and the surfaces of the two second negative electrode materials 202 are coated with a third solid electrolyte 203; one side of the third current collector 201 extends to the outside of the second negative electrode materials 202 on both sides thereof to form a negative electrode ear; the length of the third solid electrolyte 203 is 0-4 mm larger than the length of the second negative electrode material 202, and the width of the third solid electrolyte 203 is 0-4 mm larger than the width of the second negative electrode material 202, so that the third solid electrolyte 203 fully covers the corresponding second negative electrode material 202.

[0050] As a preferred implementation scheme in this embodiment, it needs to be further explained that the first solid electrolyte 304 and the third solid electrolyte 203 between the negative electrode sheet 2 and the adjacent composite electrode sheet 3 are the same solid electrolyte, which can realize ion conduction and electronic isolation between the positive electrode material and the negative electrode material through the solid electrolyte, thereby realizing series connection inside the battery cell, saving costs and reducing the overall thickness.

[0051] As a preferred implementation scheme in this embodiment, it should be further explained that the second positive electrode material 102 and the second negative electrode material 202 are both rectangular, and the area of ​​the second positive electrode material 102 is 10-50000mm 2 The length of the second negative electrode material 202 is 0-4 mm larger than the length of the second positive electrode material 102, and the width of the second negative electrode material 202 is 0-4 mm larger than the width of the second positive electrode material 102. The rectangle is easiest to realize in the process. The area of ​​the pole piece is different according to the size of the battery cell. The negative electrode material is slightly larger than the positive electrode material to ensure the safety and service life of the battery cell without affecting the capacity.

[0052] As a preferred implementation scheme in this embodiment, it needs to be further explained that the first positive electrode material 302 and the first negative electrode material 303 are both rectangular, the length of the first positive electrode material 302 is equal to the length of the second positive electrode material 102, the width of the first positive electrode material 302 is equal to the width of the second positive electrode material 102, the length of the first negative electrode material 303 is equal to the length of the second negative electrode material 202, and the width of the first negative electrode material 303 is equal to the width of the second negative electrode material 202, so as to ensure the consistency of the battery cell process and performance.

[0053] As a preferred implementation scheme in this embodiment, it needs to be further explained that both sides of the first current collector 301 are coated with insulating material 305, the first positive electrode material 302 and the first negative electrode material 303 are located between the insulating material 305 on both sides of the first current collector 301, and the positive (negative) electrode ears need to be overlapped and welded to the external structural parts. Coating with insulating material can prevent the stacked electrode ears from overlapping the negative (positive) electrode material, or overlapping the current collector to cause a short circuit.

[0054] As a preferred implementation scheme in this embodiment, it needs to be further explained that the width of the insulating material 305 is 0-4mm, the insulating material 305 overlaps the first positive electrode material 302 in the thickness direction by 0-1.5mm, and the insulating material 305 overlaps the first negative electrode material 303 in the thickness direction by 0-1.5mm, which can ensure that the insulating material has the required functions, is easy to implement in terms of process, and does not take up too much space for active materials (the internal space of the battery cell is limited, the more inactive materials there are, the less active materials can be accommodated, and the battery cell capacity is lower).

[0055] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An all-solid-state battery cell, characterized in that: The invention comprises positive electrode sheets (1) and negative electrode sheets (2) which are sequentially connected in series and arranged alternately, and any adjacent positive electrode sheets (1) and negative electrode sheets (2) are connected in series via n composite electrode sheets (3), where n is an integer and n≥1; the composite electrode sheets (3) comprise a first current collector (301), a first positive electrode material (302), a first negative electrode material (303) and a first solid electrolyte (304); a surface of the first current collector (301) facing the negative electrode sheet (2) is sequentially coated with the first positive electrode material (302) and the first solid electrolyte (304); The first current collector (301) is coated with a first negative electrode material (303) and a first solid electrolyte (304) in sequence on one side facing the positive electrode sheet (1); the length of the first solid electrolyte (304) is 0-4 mm greater than the length of the corresponding first positive electrode material (302) or the length of the first negative electrode material (303); the width of the first solid electrolyte (304) is 0-4 mm greater than the width of the corresponding first positive electrode material (302) or the width of the first negative electrode material (303).

2. The all-solid-state battery cell according to claim 1, characterized in that: n≥2, and the first solid electrolytes (304) on one side close to each other of any two adjacent composite pole pieces (3) are the same first solid electrolyte (304).

3. The all-solid-state battery cell according to claim 1, characterized in that: The positive electrode sheet (1) comprises a second current collector (101), both sides of the second current collector (101) are coated with a second positive electrode material (102), and the surfaces of the two second positive electrode materials (102) are coated with a second solid electrolyte (103); one side of the second current collector (101) extends to the outside of the second positive electrode materials (102) on both sides thereof to form a positive electrode ear; the length of the second solid electrolyte (103) is 0-4 mm greater than the length of the second positive electrode material (102), and the width of the second solid electrolyte (103) is 0-4 mm greater than the width of the second positive electrode material (102).

4. The all-solid-state battery cell according to claim 3, characterized in that: The first solid electrolyte (304) and the second solid electrolyte (103) between the positive electrode sheet (1) and the adjacent composite electrode sheet (3) are the same solid electrolyte.

5. The all-solid-state battery cell according to claim 3 or 4, characterized in that: The negative electrode sheet (2) comprises a third current collector (201), both sides of the third current collector (201) are coated with a second negative electrode material (202), and the surfaces of the two second negative electrode materials (202) are coated with a third solid electrolyte (203); one side of the third current collector (201) extends to the outside of the second negative electrode materials (202) on both sides thereof to form a negative electrode ear; the length of the third solid electrolyte (203) is 0-4 mm greater than the length of the second negative electrode material (202), and the width of the third solid electrolyte (203) is 0-4 mm greater than the width of the second negative electrode material (202).

6. The all-solid-state battery cell according to claim 5, characterized in that: The first solid electrolyte (304) and the third solid electrolyte (203) between the negative electrode sheet (2) and the adjacent composite electrode sheet (3) are the same solid electrolyte.

7. The all-solid-state battery cell according to claim 5, characterized in that: The second positive electrode material (102) and the second negative electrode material (202) are both rectangular, and the area of ​​the second positive electrode material (102) is 10-50000mm 2 The length of the second negative electrode material (202) is 0-4 mm greater than the length of the second positive electrode material (102), and the width of the second negative electrode material (202) is 0-4 mm greater than the width of the second positive electrode material (102).

8. The all-solid-state battery cell according to claim 7, characterized in that: The first positive electrode material (302) and the first negative electrode material (303) are both rectangular, the length of the first positive electrode material (302) is equal to the length of the second positive electrode material (102), the width of the first positive electrode material (302) is equal to the width of the second positive electrode material (102), the length of the first negative electrode material (303) is equal to the length of the second negative electrode material (202), and the width of the first negative electrode material (303) is equal to the width of the second negative electrode material (202).

9. The all-solid-state battery cell according to any one of claims 1 to 4, characterized in that: Both sides of the first current collector (301) are coated with insulating material (305), and the first positive electrode material (302) and the first negative electrode material (303) are located between the insulating materials (305) on both sides of the first current collector (301).

10. The all-solid-state battery cell according to claim 9, characterized in that: The width of the insulating material (305) is 0-4 mm, the insulating material (305) overlaps the first positive electrode material (302) in the thickness direction by 0-1.5 mm, and the insulating material (305) overlaps the first negative electrode material (303) in the thickness direction by 0-1.5 mm.

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