Self-Purifying Primary Solvation Sheath Enables Stable Electrode-Electrolyte Interfaces for Nickel-Rich Cathodes.

Han, Xinpeng; Xiang, Qianxin; Zhou, Chaoyi; Huang, Jin; Sun, Jie · Nano Lett · 2023

basic_science · Level V

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Abstract

Herein, we optimize the primary solvation sheath to investigate the fundamental correlation between battery performance and electrode-electrolyte interfacial properties through electrolyte solvation chemistry. Experimental and theoretical analyses reveal that the primary solvation sheath with a self-purifying feature can "positively" scavenge both the HF and PF<sub>5</sub> (hydrolysis of ion-paired LiPF<sub>6</sub>), stabilize the PF<sub>6</sub> anion-derived electrode-electrolyte interfaces, and thus boost the cycling performances. Being attributed with these superiorities, the NCM811//Li Li metal battery (LMB) with the electrolyte containing the optimized solvation sheath delivers 99.9% capacity retention at 2.5 C after 250 cycles. To circumvent the impact of excess Li content of Li metal on the performance of NCM811 cathode, the as-fabricated NCM811//graphite Li ion battery (LIB) also delivers a high-capacity retention of 90.1% from the 5th to the 100th cycle at 1 C. This work sheds light on the strong ability of the primary solvation sheath to regulate cathode interfacial properties.