Balancing Potassiophilicity and Catalytic Activity of Artificial Interface Layer for Dendrite-Free Sodium/Potassium Metal Batteries

Abstract

Potassium metal batteries (PMBs), with high energy density and low cost, are considered a promising option for grid-scale energy storage systems. However, challenges such as the uneven nucleation of K and instability of the solid electrolyte interphase (SEI) layer result in dendrite growth and poor cyclic performance, limiting practical application. To address them, constructing an artificial interface layer with rich defects can enhance the potassium affinity and promote the uniform nucleation of potassium, yet this can also catalyze electrolyte to decompose, leading to unstable SEI formation and poor cycle stability. Herein, a carbon layer with a locally ordered structure (SC-1600) is constructed as the artificial interface to achieve a balance between K affinity and catalytic activity. This optimized design allows for the uniform nucleation of potassium metal and the formation of a dense SEI layer. SC-1600@K symmetric cell can operate for 2000 h at 0.5 mA cm⁻² with a capacity of 0.5 mAh cm⁻², and the developed full cell shows a high capacity retention of 78% after 1500 cycles at 1 A g⁻¹. Besides, SC-1600@Na effectively extend the life of sodium metal batteries. This work provides a new insight for the construction of efficient K metal artificial interface layer.