Strategy for Metal Anode Protection in Advanced Energy Storage Systems

To meet the demand for higher capacity longer life batteries in a "next-generation batteries" technology, anodes with substantially higher energy density than current graphite are needed. One class - metal anodes (particularly Li, Na) - offers far higher energy density, but to date their utilization has been impeded by their high surface reactivity (especially to the organic electrolyte) and tendency to form dendrites (a shorting and safety hazard).

We have used atomic layer deposition (ALD) to create highly controlled, thin ceramic type coatings as an artificial solid electrolyte interphases (SEIs) to protect these anode surfaces by preventing dendrite formation and electrolyte decomposition. The ultrathin Al2O3 protective coating on Na stabilizes the Na-electrolyte interface and extends its cycle life under high current density (i.e., high power) cycling conditions. We have also developed a hybrid (elastomer + ceramic-type) protective coating on Li metal by combining ALD ceramic (LiPON) and electrochemical deposition of a polymeric elastomer. The hybrid layer achieves high Li conductivity while suppressing corrosion and due to electrolyte breakdown. The elastomer component provides mechanical flexibility to accommodate volume change both may play roles in the observed mitigation of dendrite growth at high current density.

These results demonstrate promise for achieving high energy density anodes with significantly enhanced chemical stability, electrochemical cyclability, and dendrite protection as needed for a viable beyond Li or Na ion battery technology.