LAUSR

Transition metal sulfides (TMSs), owing to their high theoretical specific capacity, unique chemical and physical properties, were established as promising anode materials for potassium-ion batteries. However, the large volume expansion of the well-crystallized TMSs has an important influence on the structural stability during cycling. Herein, amorphous cobalt sulfide/N-doped carbon core/shell nanoparticles (ACSNPs) are obtained and work as preeminent anode and display excellent potassium storage performance. After 200 cycles, the ACSNPs show a reversible capacity of 253.4 mAh g−1 at 50 mA g−1, with a much better cycling stability than commercial cobalt sulfide. Amorphous cobalt sulfide wrapped in a N-doped flexible carbon shell not only suppresses the aggregation of small grains, but also confines the cobalt sulfide particles and inhibits large volume expansion during K-ion intercalation/deintercalation.