(Invited) Designing Highly Stable Sodium Metal Anodes for Sodium Batteries

Abstract

Sodium (Na) metal holds great promise as an anode material for next-generation energy storage systems because of its high theoretical specific capacity, low electrochemical potential, low cost and high natural abundance. Nevertheless, the implementation of Na metal anode is still largely hindered by a number of long-lasting challenges, namely metallic Na dendrite growth and unstable solid electrolyte interphase (SEI) formation. To overcome these challenges, here we present a series of versatile tactical tunings on the Na metal anode, including manipulating the Na nucleation/growth behavior, modifying the electrode-electrolyte interface, and controlling the electrode structures, to realize highly stable and dendrite-free Na metal anodes over a wide current range and long-term cycling. Coupled with different Na cathode materials, the full cells using these regulated Na metal anodes exhibit superior electrochemical performances compared to those using commercial Na metals. More importantly, we found that despite the many similarities in the chemical and physical properties of lithium (Li) and Na, the strategy that was able to stabilize Li metal could not be directly applied to Na metal, but requires more meticulous investigations, thus providing new insights into understanding the differences between Li and Na systems.