Coupling Low‐Tortuosity Carbon Matrix with Single‐Atom Chemistry Enables Dendrite‐Free Potassium‐Metal Anode

Abstract

AbstractPotassium metal is an ideal anode for potassium‐metal batteries due to its low electrode potential and high theoretical capacity. Nevertheless, infinite volume change, uncontrollable K dendrite growth, and unstable solid‐electrolyte interfaces severely restrain its practical viability. Inspired by the vertical channels in natural wood, a spatial control strategy is proposed to address the above challenges using a low‐tortuosity carbon matrix decorated with single‐atom Co catalysts that act as K hosts (denoted as SA‐Co@HC). The homogenously supported Co atoms on the nitrogen‐doped carbon matrix reduce the nucleation energy barrier and promote the deposition kinetics of K. Furthermore, the conductive low‐tortuosity matrix can alter the electric field and allow fast K‐ion transport in the vertical direction. More importantly, the SA‐Co@HC host provides sufficient channel spaces to withstand the tremendous electrode volume change upon cycling. Benefitting from the synergetic effects of the SA‐Co@HC host, the symmetric cell using a SA‐Co@HC/K composite electrode demonstrates a dendrite‐free potassium plating/striping behavior, as well as achieving superb cycling stability of more than 2500 h at 0.5 mA cm−2 in a carbonate‐based electrolyte. The full cell coupled with potassium‐free organic cathodes, the SA‐Co@HC/K composite anode helps deliver excellent cycle and rate performances compared to the bare K anode.