Engineering Porous Carbon Nanotube Microspheres with Nickel Sulfoselenide Nanocrystals for High‐Performance Potassium‐Ion Batteries: Electrochemical Mechanisms and Cycling Stability

Nanostructured porous carbon materials are increasingly being recognized as promising anode materials for next‐generation batteries, offering advantages such as alleviating structural collapse during cycling due to their ability to accommodate volume expansion as well as high conductivity. Recent advancements include the introduction of multianions into metal compounds that segregate into distinct metal compounds after the initial electrochemical reaction. This segregation forms heterointerface that enhances electrochemical kinetics. This study introduces a novel approach using porous conductive carbon microspheres as a matrix to synthesize nickel sulfoselenide. The combined materials of the nickel sulfoselenide with porous carbon allow it to handle significant volume changes during cycling effectively. Furthermore, the formation of a heterointerfaces between nickel selenide and nickel sulfide, as well as the conversion reaction mechanism of nickel sulfoselenide with potassium ions are specifically investigated through detailed electrochemical analysis. As a result, developed nickel sulfoselenide embedded porous carbon–carbon nanotube composite shows outstanding electrochemical properties, including long cycling stability (505 mA h g −1 for 1000 cycles at 0.5 A g −1 ) and excellent rate performance (403 mA h g −1 at 5 A g −1 ) as the anode for the potassium‐ion batteries.