Enhanced Electrolyte Transport and Kinetics Mitigate Graphite Exfoliation and Li Plating in Fast-Charging Li-Ion Batteries

摘要

Despite significant progress in energy retention, lithium-ion batteries (LIBs)face untenable reductions in cycle life under extreme fast-charging (XFC)conditions, which primarily originate from a variety of kinetic limitationsbetween the graphite anode and the electrolyte. Through quantitative Li~+ lossaccounting and comprehensive materials analyses, it is directly observed thatthe operation of LIB pouch cells at 4 CC/3 (chargingdischarging) results inLi plating, disadvantageous solid-electrolyte-interphase formation, and solventco-intercalation leading to interstitial decomposition within graphite layers. Itis found that these failure modes originate from the insufficient properties ofconventional electrolytes, where employing a designed ester-based electrolyteimproved the capacity retention of these cells from 55.9 to 88.2 after 500cycles when operated at the aforementioned conditions. These metrics arethe result of effective mitigation of the aforementioned failure modes due tosuperior Li~+ transport and desolvation characteristics demonstrated throughboth experimental and computational characterization. This work reveals thevital nature of electrolyte design to XFC performance.