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 PF5 (hydrolysis of ion-paired LiPF6), stabilize the PF6 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.
Keywords: Ni-rich cathode; PF6 anion decomposition; electrode−electrolyte interface; electrolyte solvation chemistry; primary solvation sheath.