Robust Artificial Interlayer with High Ionic Conductivity and Mechanical Strength toward Long‐Life Na‐Metal Batteries

Abstract

Sodium metal, benefiting from its high theoretical capacity and natural abundance, is regarded as a promising anode for sodium‐metal batteries (SMBs). Unfortunately, the uncontrollable sodium dendrites formation caused from the sluggish ion‐transport kinetics and fragile solid electrolyte interphase (SEI) interlayer induces a low Coulombic efficiency and poor cycling stability. Constructing an artificial SEI interlayer with high ionic conductivity, stability, and mechanical toughness is an effective strategy for Na‐metal anode, yet it still presents major challenge for high current density and long cycling life. Herein, an artificial SEI interlayer composed of Na–Sn alloy, Sn, and Na2Te (denoted as NST) is designed via in‐situ conversion/alloying reaction of tin telluride (SnTe) with Na. Such artificial interlayer possesses rapid Na+‐transport kinetics and high Young's modulus (5.3 GPa), benefitting to even Na plating/stripping and suppressing Na dendrite growth. Owing to these merits, the symmetrical Na/NST cell presents an ultralong cycle life span over 1390 h with a small voltage hysteresis at 1 mA cm−2 with 1 mAh cm−2. And the Na3V2(PO4)3 (NVP)||Na/NST full cell exhibits a prolonged life of 1000 cycles with a high‐capacity retention of 88% at 5C. Herein, a promising strategy is provided to construct a high‐performance artificial interlayer for SMBs.