Rechargeable battery with shutdown layer comprising a low melting point material and an electrically conductive material
In at least one embodiment, a battery is provided comprising an anode and cathode, a separator between the anode and cathode, and a shutdown layer between the separator and the anode or cathode. The shutdown layer may include low melting point material and a conductive material within the low melting point material forming a conductive network within the shutdown layer. At a melting point temperature of the low melting point material, the conductive network is reduced such that at least a portion of the shutdown layer is substantially electrically non-conductive. The shutdown layer may be a free-standing layer or may be coated one or both of the electrodes.
1. A lithium-ion battery comprising:
an anode and cathode;
a separator between the anode and cathode; and
a shutdown layer between the separator and the anode or cathode, including a wax material and an electrically conductive material within the wax material and forming a conductive network within the shutdown layer, at a wax material melting point temperature, the conductive network is reduced such that at least a portion of the shutdown layer is substantially electrically non-conductive.
2. The battery of claim 1 , wherein below the melting point temperature of the wax material, the shutdown layer is electrically conductive.
3. The battery of claim 1 , wherein the electrically conductive material includes electrically conductive particles.
4. The battery of claim 3 , wherein the wax material includes a number of grain boundaries, and the electrically conductive particles are disposed at the number of grain boundaries of the wax material.
5. The battery of claim 3 , wherein the electrically conductive particles include conductive carbon.
6. The battery of claim 1 , wherein a shutdown layer is disposed between the separator and the anode and between the separator and the cathode.
7. The battery of claim 1 , wherein the wax material comprises from 10 to 90 weight percent of the shutdown layer.
8. The battery of claim 1 , wherein the electrically conductive material comprises from 1 to 30 weight percent of the shutdown layer.
9. The battery of claim 1 , wherein the wax material is a paraffin wax.
10. The battery of claim 1 , wherein the shutdown layer has a thickness of 1 to 50 μm.
11. The battery of claim 1 , wherein the wax material has a melting point of 70 to 150° C.
12. A method of forming a lithium-ion battery including a shutdown layer, the method comprising:
preparing a mixture of a wax material and a plurality of electrically conductive particles;
coating the mixture onto a battery anode or cathode;
drying the mixture to obtain a dried mixture including a conductive network within the wax material to obtain a shutdown layer in which at a melting point temperature of the wax material, the conductive network is reduced such that at least a portion of the shutdown layer is substantially electrically non-conductive; and
forming a lithium-ion battery including an anode and a cathode, a separator between the anode and the cathode, and the shutdown layer between the separator and the anode or the cathode.
13. The method of claim 12 , wherein the electrically conductive particles include conductive carbon.
14. The method of claim 12 , wherein upon drying, the wax material includes a number of grain boundaries and the electrically conductive particles are disposed at the number of grain boundaries.
15. The method of claim 12 , wherein the shutdown layer has a thickness of 1 to 50 μm.
16. The method of claim 12 , wherein the wax material comprises from 10 to 90 weight percent of the mixture.
17. The method of claim 12 , wherein the electrically conductive particles comprise from 1 to 30 weight percent of the shutdown layer.
18. The method of claim 12 , wherein the mixture is coated onto a battery anode and a battery cathode.
19. The method of claim 12 , wherein the wax material is a paraffin wax.
20. A lithium-ion battery comprising:
an anode;
a cathode;
a separator between the anode and cathode; and
a shutdown layer between the separator and the anode or the cathode and consisting essentially of a low melting point (LMP) material having a melting temperature between 60° C. and 200° C. and an electrically conductive material distributed throughout the LMP material and forming a conductive network within the shutdown layer; and at a melting point temperature of the LMP material, the conductive network is reduced such that at least a portion of the shutdown layer is substantially electrically non-conductive.