Fluorinated carbonate-based electrolyte engineering solvation structure for high-voltage Li||LiNiO2 cell

Ni-rich layered oxides are considered ideal positive electrode materials for next-generation state-of-the-art Li-based batteries owing to their high energy densities. However, the structural degradation of Ni-rich positive electrodes and electrolyte decomposition presents significant challenges, particularly at high cut-off voltages. Herein, we report a novel electrolyte consisting of fluorinated solvents that enables the long lifespan of a Li||LiNiO 2 cell with a cut-off voltage of up to 4.5 V. The Li||LiNiO 2 cell retains 93.8% of its initial capacity after 200 cycles. The cycling stability was ascribed to the fluorinated solvents dominating the first structural shell of Li + and deriving a robust cathode-electrolyte interphase (CEI) on the positive electrode. Compared to commercial electrolytes, the fluorinated electrolyte inhibits the structural degradation, stress corrosion cracking, and interphase side reactions of the LiNiO 2 electrode. On the Li negative electrode side, ideal Li plating/stripping and the inhibition of the attack of Ni 2+ are achieved. Furthermore, the 4.5 V-Li||LiNiO 2 cell exhibited a capacity retention of 80.2% after 100 cycles, even under extremely fast-charging conditions.