Toward High‐Performance Capacitive Potassium‐Ion Storage: A Superior Anode Material from Silicon Carbide‐Derived Carbon with a Well‐Developed Pore Structure

Potassium‐ion battery (PIB) using a carbon‐based anode is an ideal device for electrochemical energy storage. However, the large atomic size of potassium ions inevitably leads to huge volume expansion and the collapse of anodes, resulting in the severe capacity fading during the long‐term cycling. Herein, silicon carbide‐derived carbon (SiC‐CDC) with a controllable pore structure is synthesized with a concise etching approach. It exhibits a maximum capacity of 284.8 mA h g−1 at a current density of 0.1 A g−1 after 200 cycles as well as a highly reversible capacity of 197.3 mA h g−1 at a current density of 1.0 A g−1 even after 1000 cycles. A mixed mechanism of the potassium storage is proposed for this prominent performance. The interconnected pore structure with a high proportion of mesopore volume provides abundant active sites for the adsorption of potassium ions, a shortened electrolyte penetration path, and enlarged accumulation space for potassium ions, eventually leading to facilitated capacitive potassium storage inside this SiC‐CDC electrode. This work provides fundamental theories of designing pore structures for boosting capacitive potassium storage and unveils CDC‐based materials as the prospective anodes for high‐performance PIBs. High‐performance potassium‐ion batteries are constructed using a silicon carbide‐derived carbon anode. Resulting from its mesopore‐dominated structure and its appropriate specific surface area, the reaction kinetics of capacitive potassium storage are boosted. Its capacity is maintained at 284.8 mA h g−1 at a current density of 0.1 A g−1 after 200 cycles and without obvious capacity decay.