Oxygen-enriched vacancy spinel MFe2O4/carbon (M = Ni, Mn, Co) derived from metal-organic frameworks toward boosting lithium storage

Abstract

Transition metal oxide anode materials have recently been losing their importance as advanced functional and smart materials due to early capacity decay and sluggish kinetics. In order to address this issue, vacancy engineering approach can be adapted, which can effectively manipulate the electronic structure of transition metal oxide (TMO)-based electrode materials. Herein, a series of MOF-derived oxygen-rich vacancy MFe2O4/C (M = Ni, Mn, Co) materials are synthesized on a large scale via solvothermal and subsequent calcination treatment for energy storage applications in lithium-ion batteries. All the synthesized OV-NFO (NiFe2O4), OV-MFO (MnFe2O4) and OV-CFO (CoFe2O4) electrodes achieve excellent electrochemical performance, superior multiplier performance and incredible lithium-ion diffusion rate, which was found to be superior than their counterpart electrodes. The oxygen vacancy (OV) enrichment contribution to higher conductivity was realized by experimental and density functional theory (DFT) calculations results, where it has been established that OV provides additional active sites, accelerates Li+ diffusion and improves pseudocapacitive contribution. This vacancy-engineering strategy for modulating electronic structure and reaction kinetics enabled new ideas for the design and execution of other advanced transition metal-based electrode materials.