Reaction and Capacity-Fading Mechanisms of Tin Nanoparticles in Potassium-Ion Batteries

In this article, we report a study of the electrochemical performance and degradation mechanism of tin (Sn) nanoparticle anodes in potassium-ion batteries (KIBs). A high capacity of 197 mAh/g was found for the Sn nanoparticles in KIBs. In situ transmission electron microscopy characterization revealed a two-step potassiation mechanism: formation of a KSn phase after full potassiation and reversible nanopore formation during the cycling of Sn nanoparticles. However, significant capacity fading occurred after a few cycles, which was caused by the severe pulverization of the Sn nanoparticles. This work offers a fundamental understanding of the reaction and degradation mechanisms of alloying-type anodes for KIBs, shedding light on the development of high-performance KIBs.