One-Step Construction of V5S8 Nanoparticles Embedded in Amorphous Carbon Nanorods for High-Capacity and Long-Life Potassium Ion Half/Full Batteries.

Potassium ion batteries (KIBs) have attracted great attention recently as a promising large-scale energy storage system by virtue of the bountiful K resource and low standard hydrogen potential of K+/K. However, their development is hindered by the limited capacity and inferior cycling stability resulting from the large size of K+. Here, a unique vanadium sulfide@carbon nanorod is designed and synthesized for high-performance KIBs. Thanks to the hybrid structure, abundant active sites, fast ion diffusion, and capacitive-like electrochemical behavior of the electrode, the anode exhibits a large specific capacity (468 mA h g-1 after 100 cycles at 0.1 A g-1), predominant rate performance (205 mA h g-1 at 5 A g-1), and impressive cycling stability (171 mA h g-1 for 4000 cycles at 3 A g-1). Furthermore, the constructed KIB full cell demonstrates 229 mA h g-1 at 0.5 A g-1 and 86% capacity retention over 300 cycles.