SAFETY-ENHANCEMENT STATE-OF-CHARGE REDUCTION DEVICES FOR PROPAGATION RESISTANT LITHIUM-ION BATTERIES
This disclosure describes safety-enhancement state-of-charge (SOC) reduction devices for propagation resistant lithium-ion batteries. The SOC reduction device is added between the electrodes of a lithium-ion cell. Before thermal runaway can occur, the SOC reduction device shorts the electrodes according to a trigger temperature.
1 . A battery device, comprising:
an electrochemical cell comprising a negative electrode and a positive electrode, and
a state-of-charge (SOC) reduction device within the electrochemical cell, wherein:
the SOC reduction device comprises a conductive material, and
the conductive material is operable to short the negative electrode to the positive electrode according to a trigger temperature.
2 . The battery device of claim 1 , wherein the conductive material is one of a film and a foil.
3 . The battery device of claim 1 , wherein the conductive material is the same material as a current collector of the electrodes.
4 . The battery device of claim 1 , wherein the conductive material comprises copper that is operably connected to the negative electrode.
5 . The battery device of claim 1 , wherein the conductive material comprises aluminum that is operably connected to the positive electrode.
6 . The battery device of claim 1 , wherein:
the conductive material is operably connected to the negative electrode at a location where the negative electrode is connected to a first external contact, and
the conductive material is operably connected to the positive electrode at a location where the positive electrode is connected to a second external contact.
7 . The battery device of claim 1 , wherein a current collection point of the electrochemical cell is a weld.
8 . The battery device of claim 1 , wherein SOC reduction device comprises two metals that are connected using welding.
9 . The battery device of claim 8 , wherein the welding is one of ultrasonic welding, friction welding and laser welding.
10 . The battery device of claim 1 , wherein:
the trigger temperature is higher than an operating temperature of the electrochemical cell, and
the trigger temperature is lower than a thermal propagation trigger temperature of the electrochemical cell.
11 . The battery device of claim 1 , wherein the SOC reduction device has a resistance that allows the electrochemical cell to discharge without triggering TR.
12 . The battery device of claim 1 , wherein the SOC reduction device has a resistance that allows the electrochemical cell to discharge within 1 second.
13 . The battery device of claim 1 , wherein the SOC reduction device has a resistance less than 0.1 ohms.
14 . The battery device of claim 1 , wherein the SOC reduction device comprise a conductive agent that melts between 80° C. and 200° C.
15 . The battery device of claim 14 , wherein the conductive agent is a low-temperature melting point metal.
16 . The battery device of claim 14 , wherein the conductive agent comprises one or more of: indium, lithium, tin, Bi-33 In, Sn-52 In, Sn-58Bi and Sn-9Zn.
17 . The battery device of claim 14 , wherein the conductive agent is operable to melt and bridge a gap between two conductive surfaces.
18 . The battery device of claim 1 , wherein the conductive agent has a surface energy higher than 0.5 J/m 2 .
19 . The battery device of claim 1 , wherein pressure is applied to increase an electrical conductivity of the SOC reduction device.
20 . The battery device of claim 1 , wherein the pressure is greater than 10 kPa.