Exploring ion migration in Li2MnSiO4 for Li-ion batteries through strain effects

Abstract

The orthorhombic crystal Li₂MnSiO₄ is widely studied as a potential high specific energy cathode material for rechargeable batteries. However, low ion diffusion hinders its development. In this paper, first principles calculations were performed to investigate the effect of lattice strain on the ionic diffusion and the defect formation in Li₂MnSiO₄, which are directly related to the rate performance. The computational results show that the Li₂MnSiO₄ material has a two dimensional pathway for effective lithium ion transport, and the Li ion migration barrier is sensitive to the strain applied on the lattice. When strain is applied in bc plane, the migration energy increases/decreases with compressive/tensile strain (from −5% to +5%) for both channels. Furthermore, strain applied in ab and ac planes can also affect Li migration, but the effect is not as obvious as when strain is applied in the bc plane. The Li/Mn anti-site defect cannot be produced spontaneously, and the defect formation energy slightly decreases when strain works on the lattice. In fact, an appropriate strain value can improve the rate performance of Li₂MnSiO₄ effectively for applications.