Confining MoSe Nanosheets into N-Doped Hollow Porous Carbon Microspheres for Fast-Charged and Long-Life Potassium-Ion Storage.

The potassium-ion battery (PIB) is the most promising alternative to a lithium-ion battery (LIB). Exploitation of a suitable electrode material is crucial to promote the development of PIBs. The MoSe material has attracted much attention due to its high theoretical capacity, unique layered structure, and good conductivity. However, the potassium storage property of MoSe has been suffering from structural fragmentation and sluggish reaction kinetic caused by large potassium ions upon insertion/extraction, which needs to be further improved. Herein, the MoSe nanosheets are confined into N-doped hollow porous carbon microspheres (MoSe@N-HCS) by spray drying and high-temperature selenization. It delivers a superior rate performance of 113.7 mAh g at 10 A g and remains at a high capacity of 158.3 mAh g at 2 A g even after 16 700 cycles for PIBs. The excellent electrochemical performance can be attributed to unique structure, N-doping, and robust chemical bonds. The storage mechanism of MoSe for potassium ions was explored. The outstanding properties of MoSe@N-HCS make it a promising anode material for PIBs.