Boosting interfacial kinetics in extremely fast rechargeable Li-ion batteries with linear carbonate-based, LiPF₆-concentrated electrolyte

Amidst the surging demand for battery-powered automobiles, it is crucial to tackle the safety risks of Li plating triggered by high cell polarization to achieve extremely fast charging (XFC) of Li-ion batteries. This study explores the impact of Li⁺ desolvation and solid-electrolyte interphase (SEI) chemistry on cell polarizations by utilizing linear carbonate (LC)-based, LiPF₆-concentrated electrolytes (LPCEs). In the LC family, dimethyl carbonate (DMC) is thermodynamically preferred to facilitate desolvation kinetics, thereby lowering the charge-transfer barrier at the graphite anode. For effective graphite passivation and faster Li⁺ diffusion crossing the SEI, fluoroethylene carbonate (FEC) can help build up a thin and fluorinated SEI and reinforce the XFC cycling stability of graphite||NMC622 full cells (3.0 mAh cm⁻²; N/P ratio = 1.1), exhibiting 94.3% capacity retention over 500 cycles under a 10-min charging condition. The excellent XFC performance is practically validated using a 1.2-Ah pouch cell, demonstrating three times higher capacity retention over 200 cycles while suppressing Li plating-triggered cell swelling compared to conventional electrolytes. Unraveling the cell polarization governed by electrolyte chemistry provides valuable insights regarding future electrolyte designs for improving the XFC capabilities of Li-ion batteries.