Selective Potassium Deposition Enables Dendrite-Resistant Anodes for Ultrastable Potassium-Metal Batteries.

Abstract

Instability at the solid electrolyte interface (SEI) and uncontrollable growth of potassium dendrites have been pressing issues for potassium-ion batteries. Herein, a self-supporting electrode composed of bismuth and nitrogen-doped reduced graphene oxide (Bi₈₀ /NrGO) is designed as an anode host for potassium-metal batteries. Following the molten potassium diffusion into Bi₈₀ /NrGO, the resulting K@Bi₈₀ /NrGO exhibits unique hollow pores that provide K⁺ -diffusion channels and deposition space to buffer volume expansion, thus maintaining the electrode structure and SEI stability. The K@Bi₈₀ /NrGO also provides a controlled electric field that promotes uniform K⁺ flux, abundant potassiophilic N sites, and Bi alloying active sites, collectively enabling precise nucleation and selective deposition of potassium to achieve dendrite-resistant anodes. With the K@Bi₈₀ /NrGO-based optimized electrodes, the assembled K@Bi₈₀ /NrGO symmetrical cells can sustain stable cycling over 3000 h at a current density of 0.2 mA cm^-2 . Full cells with a Prussian blue cathode and K@Bi₈₀ /NrGO anode exhibit high stability (with no degradation for 1960 cycles at 1000 mA g^-1 ) with 99% Coulombic efficiency. This work may lead to the design of anodes with the triple attributes of precise nucleation, smooth diffusion, and dendrite inhibition, ideal for developing stable potassium-metal anodes and beyond.