For large-format high-energy lithium-ion battery (LIB), formation of internal short circuit (ISC) often results in catastrophic thermal runaway, leading to fire and/or explosion. It imposes touch challenges to system safety and robustness for electric vehicles, personal electronics, large-scale energy storage systems, to name a few. It is desirable to prevent thermal runaway at the electrodes level, through cell engineering.

Recently, we developed “super-safe” LIB cells with functional current collectors (FCC). Independent of the active materials layers, FCC contains physical features that can favorably control the damage mode of electrodes. Once ISC is formed, FCC works as an effective “fuse” that shuts down the internal short current immediately, before heat generation even begins.

The advantages of FCC include:

1. FCC is highly effective. Our experiments on FCC-based pouch cells showed only mild temperature increase upon severe impact penetration of metal; reference cells exploded instantaneously under the same abuse testing condition.
2. FCC does not affect the cell cycle life, since the thermal runaway mitigation process is non-chemical and decoupled from the electrochemical reactions.
3. FCC does not affect the mass production of active materials and other cell components. The failsafe mechanisms are carried entirely by the current collectors.
4. Similar FCC technique can be applied to a wide variety of battery chemistries, including future high-energy batteries.
5. FCC adds little mass or volume to battery cell, and is cost efficient.
6. FCC can be produced through a roll-to-roll procedure.