Interfacial Stabilization of a Graphene-Wrapped Cu2S Anode for High-Performance Sodium-Ion Batteries via Atomic Layer Deposition

Sodium-ion batteries (SIBs) have attracted increasing attention for storing renewable clean energy, owing to their cost-effectiveness. Nonetheless, SIBs still remain significant challenges in terms of the availability of suitable anode materials with high capacities and good rate capabilities. Our previous work has developed and verified that Cu2S wrapped by nitrogen-doped graphene (i.e., Cu2S@NG composite), as an anode in SIBs, could exhibit a superior performance with ultralong cyclability and excellent rate capability, mainly due to the multifunctional roles of NG. However, the Cu2S@NG anode still suffers from continuous parasitic reactions at low potentials, causing a rapid performance deterioration. In this study, we investigated the effects of a conformal Al2O3 coating via atomic layer deposition (ALD) on the interfacial stability of the Cu2S@NG anode. As a consequence, the ALD-coated Cu2S@NG electrode can deliver a high capacity of 374 mAh g(-1) at a current density of 100 mA g(-1) and achieve a capacity retention of similar to 100% at different rates. This work verified that surface modification via ALD is a viable route for improving SIBs' performances.