From charge storage mechanism to performance: A strategy toward boosted lithium/sodium storage through heterostructure optimization

Solving the problems of low electrical conductivity and poor cycling durability in transition metal oxides-based anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) has already turned into an urgent requirement. In this paper, we successfully synthesized Co₂VO₄/Co compounds with Co-V-MOF (metal-organic framework) as a sacrificial template and investigated their electrochemical mechanism in order to improve the electrochemical properties of LIBs and SIBs. The optimized heaping configuration and the existence of metallic Co catalyzed the formation of radical ions, thereby facilitating higher conductivity, shortening Li⁺ and Na⁺ transport paths, and providing more active sites. Co₂VO₄/Co constructed with 2-methylimidazole as a ligand showed a discharge capacity of 1605.1 mA h g⁻¹ after 300 cycles at 0.1 A g⁻¹ in LIB and 677.2 mA h g⁻¹ in SIB. Density functional theory (DFT) calculation emphasizes the crucial role of Co₂VO₄/Co in enhancing electrode conductivity, decreasing the migratory energy barrier, and thereby strengthening electrochemical properties. This heterostructure building technique may pave the way for the development of high-performance LIBs and SIBs. Furthermore, the problem of the low first-loop coulombic efficiency faced by transition metal oxides is improved.