Enabling Superior Electrochemical Properties for Highly Efficient Potassium Storage by Impregnating Ultrafine Sb Nanocrystals within Nanochannel‐Containing Carbon Nanofibers

Sb‐based nanocomposites are attractive anode materials for batteries as they exhibit large theoretical capacity and impressive working voltage. However, tardy potassium ion diffusion characteristics, unstable Sb/electrolyte interphase, and huge volume variation pose a challenge, hindering their practical use for potassium‐ion batteries (PIBs). Now, a simple robust strategy is presented for uniformly impregnating ultrasmall Sb nanocrystals within carbon nanofibers containing an array of hollow nanochannels (denoted u‐Sb@CNFs), resolving the issues above and yielding high‐performance PIBs. u‐Sb@CNFs can be directly employed as an anode, thereby dispensing with the need for conductive additives and binders. Such a judiciously crafted u‐Sb@CNF‐based anode renders a set of intriguing electrochemical properties, representing large charge capacity, unprecedented cycling stability, and outstanding rate performance. A reversible capacity of 225 mAh g −1 is retained after 2000 cycles at 1 A g −1 .