Three dimensional frameworks of super ionic conductor for thermodynamically and dynamically favorable sodium metal anode

Abstract

Metallic sodium anodes are highly attractive due to the high specific capacity and natural abundance, but the uncontrollable Na dendrite issues impede its practical implementation. Nucleation, growth and dissolution of Na are an inseparable sequential process, so the variations in these reaction thermodynamics and kinetics could lead to dendrite proliferation and low utilization of Na anode. It appears to be particularly important to optimize the whole continuous process by introducing a super ionic conductor material, Na3V2(PO4)3 (NVP), as the modulation medium of continuous nucleation, growth and dissolution to suppress Na dendrite in this work. The initial intercalation reaction of Na+ into NVP thermodynamically improves the affinity of Na and NVP, leading to a low-barrier nucleation and homogenous Na-ion flux. Importantly, the super ionic conductor dynamically provides ultrafast migration channels to promote the interfacial Na-ion transport, contributing to a reduced electrochemical polarization and uniform Na-ion distribution. As a result, the cell displays superior rate performance and improved cycling stabilities in both half and full cells. This work proposes a new strategy for a thermodynamically and dynamically favorable nucleation and reversible plating/stripping of Na, which can be extended to other metal anodes.