Thiourea treatment broadens the lattice structure to enhance the electrochemical stability of lithium-rich manganese-based materials

Abstract

The non-aqueous sol–gel method is widely used to prepare metal oxides due to its superior ability to modulate nanostructures. However, Li_1.2Mn_0.54Ni_0.13Co_0.13O₂, a lithium-rich manganese-based material synthesized by this method, exhibits a high specific surface area. This high surface area can increase side reactions and cause a rapid decline in capacity. Sulfur doping on the surface of the material is achieved through secondary modification with thiourea treatment, resulting in enhanced electrochemical properties and stability. Elemental and morphological characterization, along with electrochemical testing, shows that sulfur surface doping effectively mitigates the rapid capacity decay associated with a high specific surface area. The high specific surface area, combined with the lattice broadening effect of sulfur doping, is significantly improving the kinetic polarization of the cell and enhancing both its performance and cycle stability. At 0.1C, the specific capacity of the cell increases from 244.4 mAh/g to 274.2 mAh/g in the first cycle. Additionally, the capacity retention rate improves from 48 to 70% after 300 cycles at 1C.