Historically lithium metal batteries failed to reach mass adoption due to safety reasons. Internal shorts due to lithium dendrite penetration through the separator are the most likely culprit. These shorts are very difficult to detect since the battery shows little to no symptom prior to failure. In order for lithium metal batteries to return to the market, it is imperative to develop safety mechanisms that can detect and intercept lithium dendrites.

We have focused on the development of novel separators that can respond to lithium dendrite penetration. For example, a Janus separator with one side coated with a “partially electronically conducting” layer is shown to control internal short circuit current and safely drain the charge in the battery to render it harmless. We are actively pursuing next-generation designs that can be implemented in both lithium-ion and lithium metal batteries.

A Janus separator effectively controls the internal short resistance and short current thus preventing catastrophic thermal runaway events.

Draining Over Blocking: Nano-Composite Janus Separators for Mitigating Internal Shorting of Lithium Batteries, Matthew S. Gonzalez, Qizhang Yan, John Holoubek, Zhaohui Wu, Hongyao Zhou, Nicholas Patterson, Victoria Petrova, Haodong Liu, and Ping Liu, Advanced Materials, 2020, 1906836