Ultrasmall antimony nanodots embedded in carbon nanowires with three-dimensional porous structure for high-performance potassium dual-ion batteries

Abstract

• The free-standing Sb@NCNWs were obtained through a simple method. • The Sb@NCNWs showed high specific capacity and good cycling performance. • The characterizations unveiled the energy storage mechanism of the PDIBs. Recently, potassium dual-ion batteries (PDIBs) have attracted considerable attention owing to the advantages of low cost, environmental friendliness, and high working voltage. However, the lack of suitable anode materials to adapt the slow diffusion of K + ions leads to the low capacity and poor cycling stability of PDIBs, which seriously impedes their further development. Herein, a simple strategy is proposed to in-situ encapsulate ultrasmall Sb nanodots into N-doped carbon nanowires (Sb@NCNWs) with a three-dimensional (3D) porous structure, yielding high-performance anodes for PDIBs. The nitrogen doping and 3D porous structure can facilitate the transport of electrons and K + ions, while the carbon matrix can effectively buffer the volumetric change of Sb nanodots during the charge/discharge process. Combining this Sb@NCNWs anode with expanded graphite cathode, we construct a novel PDIB with the alloying and intercalation mechanism in the anode and cathode, respectively. The PDIB displays a high capacity of 218 mAh g −1 at 0.2 A g −1 (based on anodes) and capacity retention of 92.5% after 400 cycles at 0.4 A g −1 , which is the best performance among the previously reported PDIBs.