Focus on lithiation kinetics of selenium-doped NiO@C electrodes with multistage pore structure

Abstract

Nickel oxide (NiO) has received considerable attention as an anode for lithium-ion batteries (LIBs) due to its superior theoretical specific capacity and cycling stability. However, its low conductivity as a wide bandgap semiconductor and sluggish lithiation kinetics are still obstacles to its widespread commercial use. In this study, we have developed a Se-doped NiO@C microsphere with a multistage pore structure. The Se-doped NiO@C shows satisfactory specific capacity and cycling stability when used as an anode for LIBs. Specifically, it exhibits a specific capacity of 1622.2 mAh g−1 after 190 cycles at 0.1 A g−1, and a capacity retention of 79.3 % after 1500 cycles at 2 A g−1. The Se-doped NiO@C exhibited improved lithiation reaction kinetics due to its hierarchical pore structure, as indicated by rate performance, pseudocapacitance contribution, and galvanostatic intermittent titration technique. Furthermore, DFT calculations revealed that the addition of selenium altered the band structure of NiO, resulting in a narrower forbidden band width and faster charge transfer. Meanwhile, the electrons provided by selenium enhance the density of states of elemental oxygen and improve the adsorption energy of lithium ions. This study provides insights into the structure and composition necessary for improving the hysteresis kinetics of oxide electrodes.