Delocalized spin-polarized electrons enhance the performance of ion batteries

Abstract

Numerous studies have confirmed that delocalized electron engineering can enhance the performance of rechargeable batteries. However, the impact of spin-polarized electrons induced by electronic correlation effects remains to be clarified. Herein, we introduce vacancies into the two-dimensional ferromagnetic material VSe₂ to generate delocalized spin-polarized electrons and investigate the regulatory effect of these spin electrons on the performance of cation batteries. Electronic structure analysis reveals that both V vacancies and Se vacancies generate delocalized electrons. Compared with pristine VSe₂, VSe₂ with V vacancies (VSVV) and VSe₂ with Se vacancies (VSSV) can significantly enhance the performance in Li⁺, Na⁺, Mg²⁺, and Ca²⁺ batteries. We compare the performance of various ion batteries based on different substrates (VSe₂, VSVV, and VSSV) including ion diffusion barriers, transferred charges, theoretical capacity, and open-circuit voltage. Among these, Se vacancies induce a stronger spin polarization and ion batteries based on VSSV exhibit superior performance (in Mg²⁺ batteries, before and after the introduction of Se vacancies, the ion diffusion energy barriers and open-circuit voltages decreased by 52.3% and 30.6%, respectively, while the transferred charges and theoretical capacities increased by 37% and 10%, respectively). This study provides insights into exploring the relationship between electronic spin polarization and battery performance enhancement.