Towards Dendrite‐Free Potassium‐Metal Batteries: Rational Design of a Multifunctional 3D Polyvinyl Alcohol‐Borax Layer

Abstract

Km etal is the optimal anode for K-ion batteries because of its high capacity and lowoperating potential, but it suffers from fast capacity fading and safety issues due to an unstable solid electrolyte interphase (SEI) and continuous Kdendrite growth. Herein, to obtain promising potassium-metal batteries,a3D polyvinyl-alcohol (PVA)-borax layer is designed, which enables ad endrite-free K-plating/stripping process.T he protective layer possesses good wettability,h igh K-ion diffusivity,a nd good structural stability,w hich enables a" uniform and underneath plating" behavior,t herefore exhibiting as table electrochemical performance.A saresult, Cu current collector with PVA-borax (PVA-borax@Cu) exhibits as table cycling lifetime for 700 ha t0 .5 mA cm À2 and 500 hat1mA cm À2 at 10 %depth of discharge (DOD) without dendrite formation. Even at ah igh utilization of 25 %D OD and 50 %D OD,t he PVA-borax@Cu shows as table cycle for 180 hand 100 h, respectively.