Stabilizing Residual Monomers within <i>In Situ</i> Polymerized Electrolytes for High-Voltage Lithium Metal Batteries
Zhenzhong Sun, Jinlin Yang, Yao Wu, Fanbin Meng, Yuxiang Niu, Hongfei Xu, Yupeng Zhu, Bolong Hong, Zhiyu Chen, Jinlong Zhu, Qian He, Gang Wu, Wei Chen
Abstract
Poly(1,3-dioxolane) (PDOL)-based electrolyte has gained wide attention due to its high compatibility with the lithium metal anode, intimate contact with electrodes, and high ionic conductivity. However, its application in high-voltage batteries is limited because the residual DOL monomers are prone to oxidation at high voltage. Here, we report that LiDFOB-initiated in situ polymerization stabilizes these residual monomers, thus overcoming the oxidation-related limitations of PDOL-based electrolytes. This approach promotes the formation of a thermodynamically stable Li + –DOL–DFOB – solvation structure and DOL–PDOL clusters, reducing the oxidative decomposition of the residual DOL monomers and extending the electrochemical stability window up to 5.0 V vs Li + /Li. It also enhances ionic conductivity (4.39 mS cm –1 ), and facilitates the formation of a uniform, F-rich cathode-electrolyte interphase. Electrochemical tests and computational simulations reveal that the reduced Li + –PDOL interactions in the designed PDOL promote higher ionic mobility and electrochemical stability. Consequently, Li||LiCoO 2 cells using the designed PDOL exhibit remarkable cycling performance, maintaining 80% capacity retention over 760 cycles at a cut-off voltage of 4.35 V. These findings establish PDOL as a transformative electrolyte for high-voltage lithium metal batteries.