Enhanced Electrolyte Transport and Kinetics Mitigate Graphite Exfoliation and Li Plating in Fast‐Charging Li‐Ion Batteries. Issue 5 (19th December 2022) - Gao, Hongpeng
Abstract: 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 limitations between the graphite anode and the electrolyte. Through quantitative Li + loss accounting and comprehensive materials analyses, it is directly observed that the operation of LIB pouch cells at 4 C||C/3 (charging||discharging) results in Li plating, disadvantageous solid‐electrolyte‐interphase formation, and solvent co‐intercalation leading to interstitial decomposition within graphite layers. It is found that these failure modes originate from the insufficient properties of conventional electrolytes, where employing a designed ester‐based electrolyte improved the capacity retention of these cells from 55.9% to 88.2% after 500 cycles when operated at the aforementioned conditions. These metrics are the result of effective mitigation of the aforementioned failure modes due to superior Li + transport and desolvation characteristics demonstrated through both experimental and computational characterization. This work reveals the vital nature of electrolyte design to XFC performance. Abstract : In this work, electrolyte design for extreme fast‐charging is demonstrated through both experimental and computational characterization. It is demonstrated that interstitial solid electrolyte interphase formation between graphite layers, Li plating, and solvent cointercalation all limit fast‐charging cyclability, but are eliminated by the designed ester‐based electrolyte, which significantly improves the capacity retention in lithium‐ion battery pouch cells subjected to fast‐charge cycling.