Confining MoSe 2 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 2 material has attracted much attention due to its high theoretical capacity, unique layered structure, and good conductivity. However, the potassium storage property of MoSe 2 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 2 nanosheets are confined into N-doped hollow porous carbon microspheres (MoSe 2 @N-HCS) by spray drying and high-temperature selenization. It delivers a superior rate performance of 113.7 mAh g -1 at 10 A g -1 and remains at a high capacity of 158.3 mAh g -1 at 2 A g -1 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 2 for potassium ions was explored. The outstanding properties of MoSe 2 @N-HCS make it a promising anode material for PIBs.