Multifunctional Interphase Layer Enabling Superior Sodium Metal Battery under Ambient Temperature and -40 °C.

Sodium (Na) metal anode with high theoretical capacity and low-cost is promising to construct high-energy-density metal battery. However, the unsatisfactory interface between Na and liquid electrolyte induces tardily ion transfer kinetics and dendritic Na growth, especially at ultra-low temperature (-40 °C). Herein, an artificial heterogeneous interphase consisting of disodium selenide (Na 2 Se) and metal vanadium (V) is produced on the surface of Na (Na@Na 2 Se/V) via an in-situ spontaneous chemical reaction. Such interphase layer possesses high sodiophilicity, excellent ionic conductivity and high Young's modulus, which can promote Na ion adsorption and transport, realizing homogenous Na deposition without dendrites. The symmetric Na@Na 2 Se/V cell exhibits outstanding cycling lifespan of over 1790 h (0.5 mA cm -2 /1 mAh cm -2 ) in carbonate-based electrolyte. More remarkably, ab initio molecular dynamics simulations reveal that the artificial Na 2 Se/V hybrid interphase can accelerate the desolvation of solvated Na + at -40 °C. The Na@Na 2 Se/V electrode thus exhibits exceptional electrochemical performance in symmetric cell (over 1500 h at 0.5 mA cm -2 /0.5 mAh cm -2 ) and full cell (over 700 cycles at 0.5 C) at -40 °C. This work provides an avenue to design artificial heterogeneous interphase layer for superior high-energy-density metal batteries at ambient and ultra-low temperatures. This article is protected by copyright. All rights reserved.