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

Potassium 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.