Weakly Binding Molecules‐Based Fast Charging Li‐Ion Batteries

• Published in: Advanced functional materials 2024-02, Vol.34 (8), p.n/a
• Main Authors: An, Kihun, Kim, Dokyung, Tran, Yen Hai Thi, Vu, Dung Tien Tuan, Park, Seong Jun, Heo, Jiyoung, Lee, Young Joo, Song, Seung‐Wan
• Format: Article
• Language: English
• Subjects: Additives; Battery cycles; Binding; Charging; Diffusion coefficient; Electrolytes; fast charging Li‐ion batteries; Graphite; Kinetics; Li dendrites‐free graphite anodes; Lithium-ion batteries; low viscosity electrolytes; lowered desolvation energy; promoted diffusion kinetics; Solid electrolytes; weakly binding solvent molecules
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202311782

Fast charging of Li‐ion batteries (LIBs) beyond standard 0.3 C (charged in 3.3 h) are desperately pursued but hindered by sluggish desolvation kinetics of ethylene carbonate‐based traditional electrolyte, and Li‐plating and dendrites growth at graphite anode and fire hazard. Herein, a new class of weakly binding all linear molecules‐based nonflammable electrolyte (WNLE) is reported, comprising 1 m LiPF6 in ethyl methyl carbonate and 2,2,2‐trifluoroethyl acetate with additives for 10–20 times faster charging LIBs than traditional ones. The critical benefits of WNLE are 44% lower viscosity, 62% higher Li+ diffusion coefficient, 20% higher Li+ transference number, and 17% lower desolvation energy, which promotes diffusion kinetics and desolvation kinetics of Li+ in the vicinity of graphite anode enabling dendrites‐free LIB, along with nonflammability. Under 3 C (charged in 20 min), WNLE‐based industrial 800 mAh graphite//LiNi0.8Mn0.1Co0.1O2 (high active mass 13 mg cm−2) Li‐ion pouch battery achieves outstanding 700 cycles, delivering 82% capacity retention and high Coulombic efficiencies ≈100%. Robust solid electrolyte interphase layers formed at the anode and cathode mitigate interfacial failures, making fast charge to 7 C and longer cycle‐life. This new class of electrolyte formulation is a promising solution and a new opportunity to realize safe and long operation of fast‐charging LIBs for practical applications. Weakly binding molecules‐based nonflammable and low viscosity electrolyte (WNLE) formulation comprising linear carbonate and linear fluorinated ester solvents promotes desolvation and diffusion kinetics of Li+ ion and therefore enables a fast charging and long‐cycled dendrites‐free 800 mAh Li‐ion pouch battery under 3 C (charged in 20 min).