Outstanding electrochemical and long cycle performance of the transition metal selenides embedded in porous carbon

Transition-metal selenides are drawn significant attention owing to their high energy density and theoretical capacity. Nonetheless, their inadequate conductivity, poor cycling stability, subpar rate performance, and volume expansion impede their practical application in battery systems. We effectively synthesize core-shell Cu2Se/ZnSe@NPC, Cu2Se@NPC, and Cu2Se/Co3Se4@NPC composite heterostructures utilizing ZIF-8 and ZIF-67 as precursors. The Cu2Se, ZnSe, and Co3Se4 nanoparticles added to the N-doped porous carbon (NPC) structure provide enormous active sites for the electrodes in lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). We belive that, the N-doped porous carbon (NPC) reduces the volume change impact created during the cycle process while simultaneously improving the conductivity. The Cu2Se/Co3Se4@NPC composite shows better performance and stability for SIBs, while the Cu2Se/ZnSe@NPC is outstanding for LIBs. Cu2Se/Co3Se4@NPC, Cu2Se/ZnSe@NPC, and Cu2Se@NPC electrodes exhibit a high initial capacity of 1507, 798, and 1023 mAh g-1 for LIBs, respectively. For SIBs after 1000 cycles, the capacities of the materials maintain at 310, 237, and 181 mAh g-1, respectively. Furthermore, the Cu2Se/ZnSe@NPC, Cu2Se@NPC, and Cu2Se/Co3Se4@NPC composites demonstrate exceptional rate performance for SIBs and LIBs. The reaction kinetics of Li/Na ions in the Cu2Se/ ZnSe@NPC, Cu2Se@NPC, and Cu2Se/Co3Se4@NPC composites are examined to elucidate their exceptional electrochemical performance. The results show the great potential of these composites and help us understand how different metal selenides, both alone and in different combinations, affect the creation of effective LIBs and SIBs.