3D Ag@C Cloth for Stable Anode Free Sodium Metal Batteries

While sodium metal anodes (SMAs) feature many performance advantages in sodium ion batteries (SIBs), severe safety concerns remain for using bulk sodium electrodes. Herein, a 3D Ag@C natrophilic substrate prepared by a facile thermal evaporation deposition method, which can be employed as a much safer anode-free SMA, is reported. Initially, there is no bulk sodium on the Ag@C substrate in the assembled SIBs. Upon charging, sodium will be uniformly deposited onto the Ag@C substrate and afterwards functions as a real SMA, thus inheriting the intrinsic merits of SMA and enhancing safety simultaneously. While cycling, the as-synthesized substrate demonstrates superior sodium plating/stripping cycling stability at 1, 2 and 3 mA cm(-2) with a capacity of 2 mAh cm(-2). Theoretical simulations reveal that Na ions prefer to bind with Ag and form a Na-Ag network, thus clearly revealing uniform sodium deposition on the Ag@C substrate. More importantly, a full battery based on Ag@C and Prussian white with impressive Coulomb efficiency (CE), high rate capability (from 0.1 C to 5 C) and long-term cycling life is illustrated for the first time, thus making Ag@C feasible for the establishment of anode-free SIBs with reduced cost, high gravimetric/volumetric energy density and enhanced safety.

Automated summary

A 3D Ag@C natrophilic substrate has been developed to serve as a safer anode-free sodium metal anode (SMA) in sodium ion batteries (SIBs). The substrate demonstrates superior sodium plating/stripping cycling stability and enables uniform sodium deposition, leading to improved safety and performance in SIBs. Additionally, a full battery based on Ag@C and Prussian white exhibits high Coulomb efficiency, rate capability and long-term cycling life, showing the potential for anode-free SIBs with enhanced safety and cost efficiency.