Battery cell

Abstract

The present application relates to a battery cell having a temperature switch to increase the thermal stability of the battery cell, comprising a main cell stack having an anode, a cathode, a separator between the anode and the cathode, a cathode tab, an anode tab, an electrolyte and an external encapsulation component, and an auxiliary cell separated from the main cell by a thermal insulation material. The auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary diaphragm; and the auxiliary diaphragm is arranged between the auxiliary cathode and the auxiliary anode and separates the auxiliary cathode and the auxiliary anode. And the auxiliary battery cell and the main battery cell are connected in parallel. The auxiliary separator is a collapsible electrically insulating material having a shrinkage temperature lower than the shrinkage temperature of the separator, and is configured such that when the temperature in the battery cell exceeds the shrinkage temperature of the collapsible electrically insulating material, the auxiliary separator will shrink, resulting in electrical contact between the auxiliary cathode and the auxiliary anode.

Description

Technical Field

[0001] The present disclosure relates to battery cells, and in particular to battery cells having a thermal switch connected in parallel with the cell stack thereof. Background Art

[0002] Lithium metal secondary cells are used in a variety of applications due to their high energy density and long cycle life. However, one of the main challenges associated with these cells is their thermal stability. When the internal temperature of the battery exceeds a certain limit, it leads to thermal runaway, which can cause a rapid release of the energy stored in the battery. Thermal runaway in such batteries can pose a significant safety risk.

[0003] For lithium-ion and lithium metal batteries, current technologies to limit the possibility of thermal runaway include improving the thermal stability of materials inside the cell, using additives inside the battery, or adding vents inside the cell that automatically open when the internal pressure of the cell becomes too high. Utility Model Content

[0004] A battery cell having a temperature switch to increase the thermal stability of the cell, comprising a main cell stack and an auxiliary cell, the main cell stack having an anode, a cathode, a separator between the anode, the cathode and the electrolyte, a cathode convex sheet, an anode convex sheet and an external packaging component, the auxiliary cell being separated from the main cell by an insulating material. The auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary diaphragm, the auxiliary diaphragm being arranged between the auxiliary cathode and the auxiliary anode and separating the auxiliary cathode and the auxiliary anode. The auxiliary cell and the main cell are connected in parallel. The auxiliary diaphragm is a shrinkable electrical insulating material having a shrinkage temperature lower than the shrinkage temperature of the diaphragm, and is configured so that when the temperature in the battery cell exceeds the shrinkage temperature of the shrinkable electrical insulating material, the auxiliary diaphragm will shrink, thereby causing electrical contact between the auxiliary cathode and the auxiliary anode.

[0005] Various aspects of the present application may be implemented in one or more of the following embodiments:

[0006] Item 1): A battery cell having a temperature switch to increase the thermal stability of the battery cell, comprising:

[0007] a main cell stack having an anode, a cathode, a separator between the anode and the cathode, a cathode tab, and an anode tab; and

[0008] An auxiliary cell separated from the main cell by an insulating material, wherein the auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary separator, the auxiliary separator is disposed between the auxiliary cathode and the auxiliary anode and separates the auxiliary cathode from the auxiliary anode, and wherein the auxiliary separator is a shrinkable electrical insulating material having a shrinkage temperature lower than the shrinkage temperature of the separator, and is configured such that when the temperature in the battery cell exceeds the shrinkage temperature of the shrinkable electrical insulating material, the auxiliary separator will shrink, thereby causing electrical contact between the auxiliary cathode and the auxiliary anode,

[0009] Wherein, the auxiliary battery cell and the main battery cell are connected in parallel.

[0010] Item 2): The battery cell according to item 1), wherein the auxiliary cell does not include an electrolyte.

[0011] Item 3): The battery cell according to item 1), wherein the shrinkable electrical insulating material is a low molecular weight polyethylene film, a polyvinyl chloride film or a biodegradable film.

[0012] Item 4): The battery cell according to Item 1) further includes a thermal insulator between the main cell and the auxiliary cell.

[0013] Item 5): The battery cell according to item 1), wherein the shrinkage temperature of the shrinkable electrical insulating material is lower than 170°C.

[0014] Item 6): The battery cell according to item 1), wherein the auxiliary anode is electrically connected to the anode tab.

[0015] Item 7): The battery cell according to item 1), wherein the auxiliary cathode is electrically connected to the cathode tab.

[0016] Item 8): The battery cell according to Item 1), wherein the auxiliary separator comprises multiple layers.

[0017] Item 9): A battery cell having improved thermal stability, comprising:

[0018] a main battery cell having an anode, a cathode, a separator between the anode and the cathode, a cathode tab, and an anode tab; and

[0019] an auxiliary cell separated from the main cell by a heat insulating material, wherein the auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary diaphragm, the auxiliary diaphragm is disposed between the auxiliary cathode and the auxiliary anode and separates the auxiliary cathode from the auxiliary anode, and wherein the auxiliary diaphragm is a thermal switch configured such that when the temperature in the battery cell exceeds a threshold temperature, the auxiliary diaphragm deforms to allow electrical contact between the auxiliary cathode and the auxiliary anode,

[0020] Wherein, the auxiliary battery cell and the main battery cell are connected in parallel.

[0021] Item 10): The battery cell according to Item 9), wherein the auxiliary cell does not include an electrolyte.

[0022] Item 11): The battery cell according to Item 9), wherein the auxiliary separator is a shrinkable electrical insulating material having a shrinkage temperature.

[0023] Item 12): The battery cell according to Item 11), wherein the shrinkage temperature of the shrinkable electrical insulating material is lower than the shrinkage temperature of the separator.

[0024] Item 13): The battery cell according to Item 12), wherein the shrinkage temperature of the shrinkable electrical insulating material is lower than 170°C.

[0025] Item 14): A battery cell according to Item 12), wherein the shrinkable electrical insulating material is a low molecular weight polyethylene film, a polyvinyl chloride film or a biodegradable film.

[0026] Item 15): The battery cell according to Item 12) further includes a thermal insulator between the main cell and the auxiliary cell.

[0027] Item 16): The battery cell according to item 12), wherein the auxiliary anode is electrically connected to the anode tab.

[0028] Item 17): The battery cell according to Item 16), wherein the auxiliary cathode is electrically connected to the cathode tab.

[0029] Item 18): The battery cell according to Item 9), wherein the auxiliary separator comprises multiple layers. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A battery cell according to one embodiment of the present application is shown.

[0031] Figure 2 A battery cell according to one embodiment of the present application is shown, wherein the auxiliary battery includes a multi-layer cathode-separator-anode.

[0032] Figure 3 A battery cell according to an embodiment of the present application is shown, wherein the separator of the auxiliary battery is shrunk. DETAILED DESCRIPTION

[0033] In the present disclosure, a battery cell with improved thermal stability includes a temperature switch inside the cell that is configured to cause a short circuit in an auxiliary battery connected in parallel with the main battery cell when a temperature increase occurs in the cell. The temperature switch can be a shrinkable electrically insulating material disposed between and separating the cathode electrode and the anode electrode of the auxiliary battery. When the temperature in the cell exceeds the shrinkage temperature of the shrinkable diaphragm material, the material shrinks. The auxiliary battery is located outside the main battery of the battery cell and is connected in parallel with the main battery cell. The auxiliary battery and the main battery are separated by an insulating barrier. The auxiliary battery does not contain an electrolyte, and the positive and negative electrodes need only be conductive materials, such as metals. It is critical that the shrinkage temperature of the auxiliary battery diaphragm material must be lower than the shrinkage (or other degradation that would cause the diaphragm to no longer provide an electrical insulating barrier) temperature of the diaphragm in the main battery.

[0034] When the temperature of the battery cell exceeds the shrinkage temperature of the shrinkable material, the material shrinks and the cathode electrode and anode electrode of the auxiliary battery will no longer be separated, causing a short circuit. Because the auxiliary battery and the main battery are connected in parallel, the short circuit at the auxiliary battery will cause all the energy in the battery cell to be released, thereby suppressing thermal runaway of the battery cell.

[0035] The number of layers of the auxiliary battery electrode separator can be one or more layers. The shrinkage temperature of the material can be adjusted by changing the material. Preferably, the shrinkage temperature of the separator material shrinks within the range of 80°C and can be any suitable material with such properties, including low molecular weight polyethylene film, polyvinyl chloride film and biodegradable film.

[0036] In an embodiment, Figure 1 As shown, the lithium metal battery cell includes a main battery portion, which includes a cathode tab, an anode tab, an anode, a cathode, and a separator between the anode and the cathode. The auxiliary battery is placed separately from the main battery and connected in parallel with the main battery. In addition, an insulating material is provided between the main battery and the auxiliary battery. The insulating material may be a ceramic fiber, an aerogel material, a foam material, a porous vacuum silicon material, or other suitable insulators that will help protect the main battery from overheating when the auxiliary battery is short-circuited. In addition, the insulating material may be configured to slow down the temperature change in the main cell when the external environment heats up rapidly, so that the auxiliary cell will short-circuit before the main cell overheats. For example, the insulating material may cause the temperature difference between the main cell and the auxiliary cell to be in the range of 10°C-40°C.

[0037] The auxiliary battery includes a cathode and an anode, the cathode can be, for example, a sheet of any conductive material (such as a conductive metal), and the anode can be, for example, a sheet of any conductive material (such as a conductive metal). The auxiliary battery does not contain an electrolyte. A diaphragm is disposed between the cathode and the anode and is configured to electrically insulate the cathode and the anode. Such a diaphragm is made of a material that shrinks or otherwise decomposes at a certain temperature. The shrinkage temperature is selected so that the diaphragm will shrink when the temperature of the battery cell exceeds a temperature that is approximately the same as or lower than the temperature at which the main battery will face a risk of thermal runaway, for example, below 170°C. The shrinkage temperature of the diaphragm of the auxiliary battery must be lower than the shrinkage temperature of the diaphragm of the main battery.

[0038] When the temperature exceeds the shrinkage temperature, the separator of the auxiliary battery shrinks ( Figure 3 ), the cathode and anode of the auxiliary battery will no longer be electrically isolated and will cause a short circuit, resulting in the release of all energy stored in the battery (including the main battery). Since the auxiliary battery is located outside the main battery and is thermally insulated from the main battery, the main battery will not experience a sufficient temperature increase caused by the energy release to trigger thermal runaway.

[0039] In another embodiment, Figure 2 As shown, the cell is similar to Figure 1 A battery cell in which the separator is made of a shrinkable material.

[0040] Various modifications and additions may be made without departing from the spirit and scope of the present disclosure. The features of each of the various embodiments described above may be appropriately combined with the features of other described embodiments so as to provide a variety of feature combinations in associated new embodiments. In addition, although the foregoing describes a plurality of separate embodiments, the content described herein merely illustrates the application of the principles of the present utility model. In addition, although the specific methods herein may be illustrated and / or described as being performed in a particular order, it is within the technical scope of the art that the ordering is highly variable to implement aspects of the present disclosure. Accordingly, this description is meant to be taken only as an example and does not otherwise limit the scope of the present utility model.

[0041] Exemplary embodiments have been disclosed above and shown in the accompanying drawings. Those skilled in the art will appreciate that various changes, omissions and additions may be made to the specific disclosure herein without departing from the spirit and scope of the present invention.

Claims

1. A battery cell, characterized in that: The battery cell has a temperature switch to increase the thermal stability of the battery cell, including: a main cell stack having an anode, a cathode, a separator between the anode and the cathode, a cathode tab, and an anode tab; and An auxiliary cell separated from the main cell by an insulating material, wherein the auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary separator, the auxiliary separator is disposed between the auxiliary cathode and the auxiliary anode and separates the auxiliary cathode from the auxiliary anode, and wherein the auxiliary separator is a shrinkable electrical insulating material having a shrinkage temperature lower than the shrinkage temperature of the separator, and is configured such that when the temperature in the battery cell exceeds the shrinkage temperature of the shrinkable electrical insulating material, the auxiliary separator will shrink, thereby causing electrical contact between the auxiliary cathode and the auxiliary anode, Wherein, the auxiliary battery cell and the main battery cell are connected in parallel.

2. The battery cell according to claim 1, characterized in that: The auxiliary battery cell does not include electrolyte.

3. The battery cell according to claim 1, characterized in that: The shrinkable electrical insulating material is a low molecular weight polyethylene film, a polyvinyl chloride film or a biodegradable film.

4. The battery cell according to claim 1, characterized in that: The battery cell also includes a thermal insulator between the main cell and the auxiliary cell.

5. The battery cell according to claim 1, characterized in that: The shrinkage temperature of the shrinkable electrical insulation material is lower than 170°C.

6. The battery cell according to claim 1, characterized in that: The auxiliary anode is electrically connected to the anode tab.

7. The battery cell according to claim 1, characterized in that: The auxiliary cathode is electrically connected to the cathode tab.

8. The battery cell according to claim 1, characterized in that: The auxiliary separator includes multiple layers.

9. A battery cell, characterized in that: The battery cell has improved thermal stability, including: a main battery cell having an anode, a cathode, a separator between the anode and the cathode, a cathode tab, and an anode tab; and an auxiliary cell separated from the main cell by a heat insulating material, wherein the auxiliary cell comprises an auxiliary anode, an auxiliary cathode and an auxiliary diaphragm, the auxiliary diaphragm is disposed between the auxiliary cathode and the auxiliary anode and separates the auxiliary cathode from the auxiliary anode, and wherein the auxiliary diaphragm is a thermal switch configured such that when the temperature in the battery cell exceeds a threshold temperature, the auxiliary diaphragm deforms to allow electrical contact between the auxiliary cathode and the auxiliary anode, Wherein, the auxiliary battery cell and the main battery cell are connected in parallel.

10. The battery cell according to claim 9, characterized in that: The auxiliary battery cell does not include electrolyte.

11. The battery cell according to claim 9, characterized in that: The auxiliary separator is a shrinkable electrical insulating material having a shrinkage temperature.

12. The battery cell according to claim 11, characterized in that: The shrinkage temperature of the shrinkable electrically insulating material is lower than the shrinkage temperature of the diaphragm.

13. The battery cell according to claim 12, characterized in that: The shrinkage temperature of the shrinkable electrical insulation material is lower than 170°C.

14. The battery cell according to claim 12, characterized in that: The shrinkable electrical insulating material is a low molecular weight polyethylene film, a polyvinyl chloride film or a biodegradable film.

15. The battery cell according to claim 12, characterized in that: The battery cell also includes a thermal insulator between the main cell and the auxiliary cell.

16. The battery cell according to claim 12, characterized in that: The auxiliary anode is electrically connected to the anode tab.

17. The battery cell according to claim 16, characterized in that: The auxiliary cathode is electrically connected to the cathode tab.

18. The battery cell according to claim 9, characterized in that: The auxiliary separator includes multiple layers.

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