Stable Solid Electrolyte Interface Achieved by Separator Surface Modification for High-Performance Anode-free Potassium Metal Batteries

Anode-free lithium and sodium metal batteries (N:P = 0:1) are regarded as a promising method to significantly improve the energy density of rechargeable batteries. Studies concerning separator modification of anode-free K metal batteries (AF-KMBs) are rare. Herein, reduced graphene oxide (rGO) served as a special coating layer with high conductivity and porosity to achieve high-performance AF-KMBs with good dynamic characteristics. In addition, the porosity of rGO can help form a stable solid electrolyte interface (SEI) as a soft host on Cu foil for the "K-free" anode and improve the cycling life of the AF-KMBs. As a result, the obtained AF-KMBs paired with a K0.51V2O5 cathode (Cu/rGO/K0.51V2O5) can maintain a high specific capacity of 65 mAh g-1 even after 70 cycles at 0.5 A g-1. Thus, the feasibility of AF-KMBs is a proposed future research direction.