CoS₂/S‐Doped C with In Situ Constructing Heterojunction Structure for Boosted K‐Ion Diffusion and Highly Efficient Storage

Exploring the desired anode materials to address the issues of poor structural stability tardy redox kinetics caused by large potassium ionic radius are fatal for the realization of large‐scale applications of potassium‐ion batteries. In this work, the feasibility to achieve promoted K + storage by constructing the model of CoS 2 enfolded in carbon was verified by the density functional theory calculations. And the results predicted a faster electron/potassium ion transport kinetics than bare CoS 2 by increasing electron carrier density and narrowing diffusion barrier. Therefore, an interfacial engineering strategy was applied and implemented to synthesize the CoS 2 nanoparticles enveloped in the S‐doped carbon (CoS 2 /SC) under this inspiration. The as‐prepared CoS 2 /SC composite exhibited a prominent rate capability and long cycling lifespan, delivering the high capacity of 375 mA h g −1 at 0.2 A g −1 at the 100th cycle and 273 mA h g −1 at 2 A g −1 over 300 cycles. The in/ex situ characterizations unraveled the converse mechanism of CoS 2 /SC in K + storage, showing an eventually reversible phase transformation of within the electrochemical reactions.