Molecular Association Chemistry Enables High-Voltage Fast-Charging Lithium Batteries

The ideal electrolyte for high-voltage fast-charging lithium batteries (VFC-LBs) should solve two couples of paradoxes: low solvation barriers and high ionic conductivity, high oxidative and reductive stability. A single solvent-based electrolyte is very challenging to meet this demand because of its strong correlation between energy level and polarity. Here, the study develops a strategy of molecular association chemistry to endow electrolyte solvent with moderate polarity and wide energy level that are key to VFC-LBs. A descriptor of molecular association energy contributed from non-bonding interactions is proposed to directionally screen out VFC solvents. In an optimal fluorinated ethylene carbonate-ethyl acetate electrolyte, the 4.7 V Li||LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811, 2.2 mAh cm^-2) coin cells maintain 68.4% of initial capacity at 10 C (1 C  =  220 mAh g^-1). And 400 mAh Li||NCM811 pouch cells (50 µm Li, 4.4 mAh cm^-2 NCM811) exhibit stable cycling at 2.8-4.7 V over 130 cycles. Molecular association chemistry reinforces VFC capability through inducing aggregate solvation structure and suppressing NiO phase formation. Notably, this molecular association strategy can also be readily extended to silicon@carbon||NCM811 and graphite||LiFePO₄ batteries.