Cathode wrapping strategy with metal chalcogenide nanosheet for safer and longer lasting Li-ion batteries

초록

Ni-rich layered cathode materials have been intensively explored to maximize the energy density of lithium-ion batteries (LIBs). However, their performance is compromised by unstable surface reactions in the high-voltage region, resulting in detrimental changes to the surface structure. In this study, an effective strategy to improve the long-term stability of LIBs is demonstrated. This strategy involves conformally wrapping two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets on Ni-rich layered cathodes via electrostatic interactions between positively surface-treated MoS2 and negatively charged cathode particles. The formation of MoS2 wrapping layers prevents direct interfacial contact between the cathode and the electrolyte, thereby preventing surface-triggered structural degradation and unwanted side reactions. The improved cell stability was verified, with advantages including reduced gas evolution, facile Li-ion transfer, and mitigated microcrack propagation. This 2D material-wrapping strategy allows for thin and effective coverage of the cathode surface, consequently ensuring improved safety and longer lifespans for LIBs.

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