An Unexpected Low-Temperature Battery Formation Technology Enabling Fast-Charging Graphite Anodes

The battery formation process is pivotal for constructing a solid electrolyte interphase (SEI) on graphite anodes, generally conducted at high temperatures. However, the resulting excessive SEI film causes significant lithium loss and an inferior charging rate. Herein, an unconventional low-temperature formation technology based on an innovative temperature-responsive electrolyte with an anion-dominated solvation structure at low temperature is validated. During the formation cycling at 5 °C, the enhanced anion–cation interaction, coupled with the suppressed solvent decomposition, facilitates the generation of a thin and  lithium fluoride-rich SEI film. Consequently, the graphite anodes exhibit 5C fast-charging performance (198.89 mAh g⁻¹, 53.39% of theoretical capacity), successfully overcoming the rate bottleneck of 2C commonly encountered in commercial graphite anodes, and realize 95.88% capacity retention after 400 cycles at 0.5C. Moreover, compared to traditional high-temperature formation, the low-temperature formation technology saves 52.73% (from 22.02 to 10.42 h) of formation time and reduces lithium loss from 16.76% to 7.21%. This work highlights the importance and opportunities of utilizing the low temperature as a “driving force” for regulating the solvation structure and interfacial chemistry.