Integrated high-temperature decomposable connector and lithium ion battery comprising same

Abstract

Disclosed are an integrated high-temperature decomposable connector and a lithium ion battery containing the same. The integrated high-temperature decomposable connector includes a connecting plate and supporting columns fixedly arranged on one side of the connecting plate at intervals, clamping columns are fixedly connected to the top ends of the supporting columns, and an insertion recess is formed between adjacent clamping columns; the top end surface of the clamping column and the inner sidewall of the insertion recess are each provided with a conductive layer, the clamping column is made of a high-temperature decomposable material, and the high-temperature decomposable material is formed by mixing a thermosensitive resin and a functional, additive. The conductive layer may be electrically connected to cell tabs, and the thermosensitive resin may be automatically decomposed while the temperature of cells is too high, so that the safety performance of the battery is greatly improved.

Claims

1. An integrated high-temperature decomposable connector, comprising a connecting plate and supporting columns fixedly arranged on one side of the connecting plate at intervals, clamping columns are fixedly connected to the top ends of the supporting columns, and an insertion recess is formed between adjacent clamping columns; the top end surface of the clamping column and the inner sidewall of the insertion recess are each provided with a conductive layer, materials of the clamping columns comprise a high-temperature decomposable material, and the high-temperature decomposable material is formed by mixing a thermosensitive resin and a functional additive.

2. The integrated high-temperature decomposable connector according to claim 1, wherein the decomposition temperature of the high-temperature decomposable material is 150° C.-250° C., the mass percentage of the thermosensitive resin in the high-temperature decomposable material is 70%-95%, and the functional additive is the rest.

3. The integrated high-temperature decomposable connector according to claim 1, wherein the thermosensitive resin is a polycarbonate compound; and the functional additive is a mixture of at least one of a carbon material and a glass fiber and a catalyst.

4. The integrated high-temperature decomposable connector according to claim 3, wherein the polycarbonate compound is one or more of a polycarbonate, a polyethylene carbonate, a polypropylene carbonate, a polymethyl carbonate modified with a functional group, a polyethyl carbonate modified with a functional group or PPC modified with a functional group, wherein the functional group comprises one or a combination of two or more of a hydroxyl, a carboxyl, a formyl, an amino group, and a sulfonic acid group; the catalyst is at least one of an inorganic compound or a polycarbonate modified with a functional group; and the carbon material is selected from one or a combination of two or more of a carbon black, a Ketjen black, a carbon nanotube, a graphene, a carbon fiber, and VGCF.

5. The integrated high-temperature decomposable connector according to claim 4, wherein the inorganic compound is a hydrochloride, a sulfate, a potassium hydroxide, a sodium carbonate, a potassium carbonate, a calcium carbonate, a lithium carbonate, an ammonium carbonate or a sodium bicarbonate; and the polycarbonate modified with the functional group is a polycarbonate modified by a hydroxyl, a carboxyl, a formyl, an amino group, a sulfonic acid group, a glycidyl or a combination thereof.

6. The integrated high-temperature decomposable connector according to claim 4, wherein the size of the graphene is 5 nm-200 μm; the size of the carbon black and the ketjen black is 1 nm-100 nm; the carbon nanotube is a single-wall carbon nanotube or a multi-wall carbon nanotube, and its diameter is 1 nm-50 nm, the length is 10 nm-1 mm; the diameter of the carbon fiber and VGCF is 80 nm-8 μm, BET is 5 m.sup.2/g-1000 m.sup.2/g, the length is 200 nm-1 mm; and the diameter of the glass fiber is 500 nm-50 μm.

7. The integrated high-temperature decomposable connector according to claim 1, wherein the thickness of the conductive layer is 300 nm-1 mm and its material is copper, aluminum, tin, gold, silver, platinum or an alloy; and the conductive layer is formed by chemical plating, evaporating, magnetron sputtering or screen printing methods.

8. The integrated high-temperature decomposable connector according to claim 1, wherein the cross section of the clamping column is a trapezoidal structure with a large upper part and a small lower part, an accommodating groove is formed between the adjacent supporting columns.

9. The integrated high-temperature decomposable connector according to claim 1, wherein the high-temperature decomposable material is formed according to the following preparation method: the thermosensitive resin with a mass percentage of 70%-95% is heated to, a molten state, and the rest of the functional additive is added to stir fully.

10. A lithium ion battery, comprising the integrated high-temperature decomposable connector according to any one of claims 1, wherein the insertion recess is in interference, fit with a cell tab.

11. The lithium ion battery according to claim 10, wherein the decomposition temperature of the high-temperature decomposable material is 150° C.-250° C., the mass percentage of the thermosensitive resin in the high-temperature decomposable material is 70%-95%, and the functional additive is the rest.

12. The lithium ion battery according to claim 10, wherein the thermosensitive resin is a polycarbonate compound; and the functional additive is a mixture of at least one of a carbon material and a glass fiber and a catalyst.

13. The lithium ion battery according to claim 12, wherein the polycarbonate compound is one or more of a polycarbonate, a polyethylene carbonate, a polypropylene carbonate, a polymethyl carbonate modified with a functional group, a polyethyl carbonate modified with a functional group or PPC modified with a functional group, wherein the functional group comprises one or a combination of two or more of a hydroxyl, a carboxyl, a formyl, an amino group, and a sulfonic acid group; the catalyst is at least one of an inorganic compound or a polycarbonate modified with a functional group; and the carbon material is selected from one or a combination of two or more of a carbon black, a Ketjen black, a carbon nanotube, a graphene, a carbon fiber, and VGCF.

14. The lithium ion battery according to claim 13, wherein the inorganic compound is a hydrochloride, a sulfate, a potassium hydroxide, a sodium carbonate, a potassium carbonate, a calcium carbonate, a lithium carbonate, an ammonium carbonate or a sodium bicarbonate; and the polycarbonate modified with the functional group is a polycarbonate modified by a hydroxyl, a carboxyl, a formyl, an amino group, a sulfonic acid group, a glycidyl or a combination thereof.

15. The lithium ion battery according to claim 13, wherein the size of the graphene is 5 nm-200 μm; the size of the carbon black and the ketjen black is 1 nm-100 nm; the carbon nanotube is a single-wall carbon nanotube or a multi-wall carbon nanotube, and its diameter is 1 nm-50 nm, the length is 10 nm-1 mm; the diameter of the carbon fiber and VGCF is 80 nm-8 μm, BET is 5 m.sup.2/g-1000 m.sup.2/g, the length is 200 nm-1 mm; and the diameter of the glass fiber is 500 nm-50 μm.

16. The lithium ion battery according to claim 10, wherein the thickness of the conductive layer is 300 nm-1 mm and its material is copper, aluminum, tin, gold, silver, platinum or an alloy; and the conductive layer is formed by chemical plating, evaporating, magnetron sputtering or screen, printing methods.

17. The lithium ion battery according to claim 10, wherein the cross section of the clamping column is a trapezoidal structure with a large upper part and a small lower part, an accommodating groove is formed between the adjacent supporting columns.

18. The lithium ion battery according to claim 10, wherein the high-temperature decomposable material is formed according to the following preparation method: the thermosensitive resin with a mass percentage of 70%-95% is heated to a molten state, and the rest of the functional additive is added to stir fully.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 is a structure schematic diagram of a connector in the present disclosure.

[0030] FIG. 2 is a schematic diagram of a state before the connector of the present disclosure is connected with a cell.

[0031] FIG. 3 is a schematic diagram of a state after the connector of the present disclosure is connected with a cell.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Technical schemes in embodiments of the present disclosure are clearly and completely described below in combination with the drawings in the embodiments of the present disclosure. Apparently, the described embodiments are only a part of the embodiments of the present disclosure, but not all of the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within a scope of protection of the present disclosure.

[0033] As shown in FIG. 1, an integrated high-temperature decomposable connector, including a connecting plate 11 and supporting columns 12 fixedly arranged on one side of the connecting plate 11 at intervals, clamping columns 13 are fixedly connected to the top ends of the supporting columns 12, and an insertion recess 14 is formed between adjacent clamping columns 13; the top end surface of the clamping column 13 and the inner sidewall of the insertion recess 14 are each provided with a conductive layer 16; and materials of the clamping columns 13 include a high-temperature decomposable material (the clamping column is partially or entirely made of the high-temperature decomposable material), and the high-temperature decomposable material is formed by mixing a thermosensitive resin and a functional additive.

[0034] The cross section of the clamping column 13 is a trapezoidal structure with a large upper part and a small lower part, and an accommodating groove 15 is formed between adjacent supporting columns 12, herein the insertion recess 14 is smaller in volume, and is in interference fit with the cell tab 2 and is used for inserting and connecting the cell tab 2. The volume of the accommodating groove 15 is greater than that of the insertion recess 14, and a hot gas generated by the thermal runaway of the cells may overflow in time through the accommodating groove and the insertion recess.

[0035] As shown in FIG. 2 and FIG. 3, the cell tab 2 of the cell 3 is inserted into the insertion recess 14 in the connector 1, its bottom end is located in the accommodating groove 15, and the cell tab 2 is in interference fit with the insertion recess 14. Since the top end surface of the clamping column 13 and the inner sidewall of the insertion recess 14 are each provided with a conductive layer 16, so that a circuit of each cell 3 is conducted. While a certain cell is short-circuited, the high temperature generated by it is transmitted to the clamping column 13 through the conductive layer 16, and while the temperature reaches 150° C.-250° C., the thermosensitive resin may be decomposed into carbon dioxide and water, the volume of the clamping column 13 becomes smaller, and the structure of the conductive layer 16 on the surface thereof collapses, so the cell tab 2 is separated from the conductive layer 16 to disconnect the circuit between the cells, and the occurrence of the thermal runaway is prevented.

[0036] In the present disclosure, the decomposition temperature of the high-temperature decomposable material is 150° C.-250° C., herein the mass percentage of the thermosensitive resin is 70%-95%, and the functional additive is the rest; and the thermosensitive resin is a polycarbonate compound or a polycarbonate compound modified with a functional group.

[0037] Herein the polycarbonate compound is a polycarbonate, a polyethylene carbonate or a polypropylene carbonate; the functional group is a hydroxyl, a carboxyl, a formyl, an amino group, a sulfonic acid group or a combination thereof; and the functional additive is a carbon material or a glass fiber.

[0038] In a further scheme, the carbon material is selected from one or a combination of two or more of a carbon black, a ketjen black, a carbon nanotube, a graphene, a carbon fiber, and VGCF.

[0039] Preferably, the size of the graphene is 5 nm-200 μm; the size of the carbon black and the ketjen black is 1 nm-100 nm; the carbon nanotube is a single-wall carbon nanotube or a multi-wall carbon nanotube, and its diameter is 1 nm-50 nm, the length is 10 nm-1 mm; the diameter of the carbon fiber and VGCF is 80 nm-8 μm, BET is 5 m.sup.2/g-1000 m.sup.2/g, the length is 200 nm-1 mm; and the diameter of the glass fiber is 500 nm-50 μm.

[0040] In a further scheme, the thickness of the conductive layer 16 is 300 nm-1 mm, and its material is copper, aluminum, tin, gold, silver, platinum or an alloy therebetween; and the conductive layer 16 is formed by chemical plating, evaporating, magnetron sputtering or screen printing methods.

[0041] In order to verify the decomposition start temperature, compressive strength and hardness of the clamping columns made of the high-temperature decomposable materials with different components, it is specifically tested, and shown in detail in Embodiments 1-4. In the following embodiments, % represents a mass percentage.

Contrast Example 1

[0042] 100% of a polypropylene carbonate (25511-85-7, Sigma-Aldrich) is used to prepare a cube sample with a size of 30 mm.

Embodiment 1

[0043] 85% of a polyethylene carbonate, 10% of a potassium hydroxide and 5% of an acetylene black (30 nm) are used to prepare a cube sample with a size of 30 mm.

Embodiment 2

[0044] 85% of a polypropylene carbonate, 10% of a potassium hydroxide and 5% of a carbon fiber (250 nm in diameter, and 2 μm in length) are used to prepare a cube sample with a size of 30 mm.

Embodiment 3

[0045] 80% of a polypropylene carbonate (25511-85-7, Sigma-Aldrich) and 15% of a sodium sulfate (Sigma-Aldrich) and 5% of graphene and carbon nanotube (the size of the graphene is 2 μm, there are about 8 layers in average, the carbon nanotube is a multi-wall carbon nanotube, 20 nm in diameter and 400 nm in length) are used to prepare a cube sample with a size of 30 mm.

Embodiment 4

[0046] 90% of a polycarbonate and 5% of a sodium sulfate (Sigma-Aldrich) and 5% of a glass fiber (1 μm in diameter, and 100 μm in length) are used to prepare a cube sample with a size of 30 mm.

[0047] The decomposition initiation temperature, compressive strength and Shore hardness of the samples prepared in the above Contract example 1 and Embodiments 1-4 are respectively detected, herein: a test method of thermogravimetry (TG) is based on JIS K 7121-1987, herein the corresponding temperature while the weight change is higher than 7.1% is considered to be the decomposition start temperature;

[0048] the determination of compressive strength is based on a test method of JIS K 7208, and the compressive strength is tested by a universal testing machine MCT-1150; and

[0049] a hardness test is performed according to JIS B7727 by using a model D of Nakai Seiki Co., Ltd.

[0050] Results of specific experiments are shown in Table 1 below:

TABLE-US-00001 TABLE 1 Embodiment comparison Decomposition Compressive start temperature strength Contrast example 1 300° C.  20 Mpa Embodiment 1 183° C.  90 Mpa Embodiment 2 208° C. 120 Mpa Embodiment 3 230° C. 135 Mpa Embodiment 4 210° C. 137 Mpa

[0051] By adding a certain proportion of a catalyst, the decomposition temperature of the thermosensitive resin may be reduced from the original 300 degrees to about 200 degrees, and the decomposition temperature thereof may be precisely controlled by controlling substances and amounts added. In this way, the time that the electrical connection between the cells is disconnected may be precisely controlled. In addition, by adding the carbon material or the glass fiber, the compressive strength and surface hardness of the material may be significantly improved, so that it adapts to use requirements.

[0052] In order to detect the thermal runaway time of a battery module caused by thermal decomposition material layers with different components, Contrast example 2 and Embodiments 5-7 are specially compared. For the convenience of comparison, all the thermosensitive resins in Embodiments 5-8 use a polypropylene carbonate, other polycarbonates, a polyethylene carbonate and the like are applicable, and it is not described in detail here.

Contrast Example 2

[0053] The structure of the connector 1 is shown in FIG. 1, including a connecting plate 11 and supporting columns 12 fixedly arranged on one side of the connecting plate 11 at intervals, clamping columns 13 are fixedly connected to the top ends of the supporting columns 12, and an insertion recess 14 is formed between adjacent clamping columns 13; the top end surface of the clamping column 13 and the inner sidewall of the insertion recess 14 are each provided with a conductive layer 16, and the material of the conductive layer 16 is copper; and the cross section of the clamping column 13 is a trapezoidal structure with a large upper part and a small lower part, and the insertion recess 14 is in interference fit with a cell tab 2 and used for inserting and connecting the cell tab 2.

[0054] The material of all components of the connector 1 is made of 100% of a polytetrafluoroethylene.

[0055] A module consists of 24 soft-packed cells, the size of the cell is 536*102*8.5 mm, the capacity of each cell is 55 Ah, the cell is graphite/LiFePO.sub.4(LFP), and the energy density of a single cell is 185 Wh/kg and 379 Wh/L. A connection mode of the module is 2P12S, and the specific connection mode is shown in FIGS. 2 and 3. The cell tab 2 of the cell 3 is inserted into the insertion recess 14 in the connector 1, and the cell tab 2 is in interference fit with the insertion recess 14, so that a circuit of each cell is conducted.

[0056] An experimental method is to overcharge a single cell SOC150 and observe the time for thermal runaway of the entire battery module, and it is specifically shown in Table 2.

Embodiment 5

[0057] It is the same as Contrast example 2, an only difference is that the material of the supporting column 12 and the connecting plate 11 in the connector 1 is a high thermal conductivity insulating material formed by mixing 80% of a polyethylene terephthalate and 20% of an aluminum oxide nanoparticle (50 nm in diameter) and pouring.

[0058] The clamping column 13 in the connector 1 is composed of 85% of a polypropylene carbonate, 10% of a potassium hydroxide, and 5% of a carbon fiber (200 nm in diameter and 1 μm in length), namely the polypropylene carbonate is firstly heated to a molten state, and the potassium hydroxide and the carbon fiber are added to stir and mix, then it is poured into a mold and solidified at a room temperature. Then, the top end surface of the clamping column 13 and the inner sidewall of the insertion recess 14 are compounded with conductive copper glue with a thickness of 100 μm as the conductive layer 16 by using a screen printing mode. Finally, it is spliced into the connector 1.

Embodiment 6

[0059] It is the same as Embodiment 5, and an only difference is that the clamping column 13 in the connector 1 is composed of 85% of a polypropylene carbonate, 10% of a potassium carbonate, 3% of a graphene (the size is 2 μm, and there are about 8 layers in average), and 2% of a multi-wall carbon nanotube (30 nm in diameter, and 800 nm in length), namely the polypropylene carbonate is firstly heated to a molten state, and the potassium carbonate, the graphene and the multi-wall carbon nanotube are added to stir and mix, then it is poured into a mold and formed by curing at a room temperature. Then, the top end surface of the clamping column and the inner sidewall of the insertion recess are compounded with 2 μm of silver as the conductive layer 16 by using a surface magnetron sputtering mode.

Embodiment 7

[0060] It is the same as Embodiment 5, and an only difference is that the clamping column 13 in the connector 1 is composed of 85% of a polypropylene carbonate, 10% of a potassium carbonate, 3% of a graphene (the size is 2 μm, and there are about 8 layers in average), and 2% of a glass fiber (1 μm in diameter, and 8 μm in length), namely the polypropylene carbonate is firstly heated to a molten state, and the potassium carbonate, the graphene and the glass fiber are added to stir and mix, then it is poured into a mold and formed by curing at a room temperature. Then, the top end surface of the clamping column and the inner sidewall of the insertion recess are compounded with 10 μm of aluminum as the conductive layer 16 by using a surface magnetron sputtering mode.

Contrast Example 3

[0061] A module consists of 24 soft-packed cells, the size of the cell is 536*102*8.5 mm, the capacity of each cell is 74 Ah, the cell is graphite/NCM811, and the energy density of a single cell is 250 Wh/kg and 580 Wh/L. A connection mode of the module is 2P12S, and the specific connection mode is the same as Contrast example 2, and the material of all components of the connector 1 is made of 100% of a polytetrafluoroethylene. An experimental method is to overcharge a single cell SOC150 and observe the time for thermal runaway of the entire battery module.

Embodiment 8

[0062] It is the same as Contrast example 3, and an only difference is that the material of the supporting column 12 and the connecting plate 11 in the connector 1 is a high thermal conductivity insulating material formed by mixing 80% of a polyethylene terephthalate and 20% of an aluminum oxide nanoparticle (50 nm in diameter) and pouring. The clamping column 13 in the connector 1 is composed of 85% of a polypropylene carbonate, 10% of a potassium carbonate, 3% of a graphene (the size is 2 μm, and there are about 8 layers in average), and 2% of a glass fiber (1 μm in diameter, and 8 μm in length)), namely the polypropylene carbonate is firstly heated to a molten state, and the potassium carbonate, the graphene and the glass fiber are added to stir and mix, then it is poured into a mold and formed by curing at a room temperature. Then, the top end surface of the clamping column and the inner sidewall of the insertion recess are compounded with 5 μm of aluminum as the conductive layer 16 by using a surface magnetron sputtering mode. Finally, it is spliced into the connector 1.

TABLE-US-00002 TABLE 2 Thermal runaway time of entire module Contrast example 2  5 min 20 s Embodiment 5 30 min 10 s Embodiment 6 No thermal diffusion Embodiment 7 No thermal diffusion Contrast example 3 3 min 00 Embodiment 8 35 min 45 s

[0063] Since the functional additive (catalyst+carbon material and/or glass fiber) is added to the connector in Embodiments 5-8 or the clamping column raw material in the connector, the thermal runaway time of the entire module is prolonged, and the safety is improved.

[0064] It is found by comparing Contrast example 2 and Embodiments 5-7 that, because the functional additive with the mass percentage of 15% is added to the resin in Embodiments 5-7, the thermal runaway time is significantly prolonged, and the thermal diffusion does occur in Embodiments 6-7.

[0065] By comparing Contrast example 3 and Embodiment 8, on the battery module with the higher energy density, the functional additive is added in Embodiment 8, and the time for thermal runaway is also greatly prolonged.

[0066] This is because the clamping column 13 in the connector 1 is made of a high-temperature decomposable material, and the high-temperature decomposable material is formed by mixing the thermosensitive resin and the functional additive. While being connected, the cell tab 2 of the cell 3 is inserted into the insertion recess 14 in the connector 1, and the cell tab 2 is in interference fit with the insertion recess 14, so that a circuit of each cell is conducted. While a certain cell is short-circuited, the high temperature generated by it is transmitted to the clamping column 13 through the conductive layer 16, and while the temperature reaches 150° C.-250° C., the thermosensitive resin may be decomposed into carbon dioxide and water, the volume of the clamping column 13 becomes smaller, and the structure of the conductive layer 16 on the surface thereof collapses, so the cell tab 2 is separated from the conductive layer 16 to disconnect the circuit between the cells, and the occurrence of the thermal runaway is prevented.

[0067] From the above description, the battery module using the connector of the present disclosure may be disconnected in time under the same circumstance, to avoid the thermal runaway of the overall module. On the high-energy-density cell using NCM811, the time for thermal runaway of the module may also be significantly prolonged. If the module composed of the high-temperature decomposable connector of the present disclosure is not used, while the cell is overcharged and a short circuit occurs, the connection between the cells may not be disconnected in time, and the entire module is affected.

[0068] Although this description is described according to the embodiments, not every embodiment only includes an independent technical scheme. This description mode in the description is only for clarity. Those skilled in the art should take the description as a whole, and the technical schemes in each embodiment may also be appropriately combined, to form other embodiments that may be understood by those skilled in the art.

[0069] Therefore, the above are only preferred embodiments of the present disclosure, and are not intended to limit a scope of implementation of the present disclosure, namely all equivalent transformations made according to the present disclosure are within a scope of protection of the present disclosure.