Toward robust lithium–sulfur batteries via advancing Li2S deposition

Abstract

Lithium–sulfur batteries (LSBs) with two typical platforms during discharge are prone to the formation of soluble lithium polysulfides (LiPS), leading to a decrease in the cycling life of the battery. Under practical working conditions, the transformation of S₈ into Li₂S is cross-executed rather than a stepwise reaction, where the liquid LiPS to solid Li₂S conversion can occur at a high state of charge (SOC) to maintain the current requirement. Therefore, advancing Li₂S deposition can effectively reduce the accumulation of LiPSs and ultimately improve the reaction kinetics. Herein, a “butterfly material” GeS₂-MoS₂/rGO is used as a sulfur host. Rich catalytic heterointerfaces can be obtained via the abundant S–S bonds formed between GeS₂ and MoS₂. MoS₂ (left wing) can enhance LiPS adsorption, while the lattice-matching nature of Fdd2 GeS₂ (right wing) and Fmm Li₂S can induce multiple nucleation and regulate the 3D growth of Li₂S. Li₂S deposition can be advanced to occur at 80% SOC, thereby effectively inhibiting the accumulation of soluble LiPSs. Attributed to the synergistic effect of catalytic and lattice-matching properties, robust coin and pouch LSBs can be achieved.