Ultra-high areal capacity, ultra-long life, dendrite-free sodium metal anode enabled by antimony-based Na-ion conducting artificial SEI layers

Abstract

Sodium metal (Na) is a promising anode material for Na metal batteries and solid-state sodium batteries, because of its high theoretical capacity, favorable electrochemical potential, and cost effectiveness. Nevertheless, practical applications of sodium metal anode are hindered by uncontrolled dendrite growth owing to chemical instability of the heterogeneous solid electrolyte interphase layer. In this work, we proposed a simple interface modification strategy employing several antimony-based Na-ion conducting solid electrolyte complexes as protective artificial SEI layer over Na metal. The Na-ion conducting interphases are robust and highly Na-ion conductive to attain uniform sodium ion flux with a small overpotential. Importantly, Na anode with antimony sulfide based solid electrolyte SEI layers exhibited the high-rate performance (10 mA cm−2) along with a remarkable capacity of 30 mAh cm−2, and life span of ∼ 1100 h. We observe that replacing the conventional artificial SEI layers, employing alloy type interface with Na-ion conducting solid electrolyte as artificial SEI components will improve the mechanical robustness at high current and high-capacity conditions. The sodium metal batteries employing modified metal anodes and high voltage Na1.2Mn0.8O1.5F0.5 cathode, exhibited excellent stability and high efficiency at 1C rate. Furthermore, the modified metal anodes are well-compatible with Na3SbS4 solid-state electrolyte, and the symmetrical solid-state battery exhibited a stable interface. Our strategy holds significant promise and has the potential for widespread application in theadvancement of high-energy sodium metal batteries and solid-state sodium batteries.