Non-Completely Selenized Cu-Ose Nanowires as Potassium-Philic Host for Anode-Free Potassium Metal Batteries

Abstract

In contrast to conventional potassium-metal batteries (PMBs), anode-free configurations can greatly enhance the gravimetric/volumetric energy densities and provide maximum safety. However, realizing K metal plating/stripping on a bare current collector with high reversibility is challenging since the substrates usually suffer from high nucleation overpotential, K dendrites and low Coulombic efficiency (CE). Herein, long lifespan anode-free PMBs were realized by using a non-completely selenized Cu-OSe nanowires (NWs) as potassium-philic host. It is found that the Cu-OSe active sites provide a low energy barrier for K nucleation. Additionally, the low K+ transport energy promotes facile K diffusion behavior on Cu-OSe NWs surface. Thus, Cu-OSe NWs achieves high reversibility of K plating/stripping over 950 hours in K//K symmetric cells at 1 mA cm–2/1 mAh cm–2. The constructed potassium-metal full cell K0.5MnO2//Cu-OSe NWs with K plating capacity of 10 mAh cm-2 achieves over 520 cycles with high capacity retention of 81.8%, and the corresponding anode-free battery acquired a capacity retention of 63.5% over 200 cycles. The fundamental understanding on the effect of Cu-OSe active sites on facile and uniform K deposition will provide guidelines for designing future commercial long lifespan anode-free PMBs.

Keywords: Potassium-metal batteries, anode-free, K dendrites, Cu nanowires