Enhanced cycle life of lithium metal batteries via modulating the lithium-ion solvation sheath with a cross-linked gel polymer electrolyte

Abstract

Lithium metal batteries (LMB) are being extensively studied as next-generation batteries. However, low cyclability still hinders their application due to the high reactivity and dendrite growth of the lithium metal. Accordingly, designing a stable solid electrolyte interphase (SEI) to suppress side reactions and dendrite growth is crucial. Herein, we prepare cross-linked gel polymer electrolytes (GPEs) containing localized high-concentration electrolytes, which tune the Li+ solvation sheath to construct a robust, ion-conductive SEI on Li anode. The weak binding between Li cations and carbonyl groups in trimethylolpropane trimethacrylate used as a cross-linking agent enhances the coordination between Li cations and anions, promoting the formation of inorganic-rich SEI on the Li metal anode. The cell assembled with thin Li metal anode (20 μm), GPE, and LiNi0.8Co0.1Mn0.1O2 cathode (3.1 mAh cm−2) exhibits a superior capacity retention of 93.5 % after 200 cycles at 0.33C with a high energy density of 233.1 Wh kg−1. The enhanced cycling stability of the GPE-based cell is systematically compared to that of the liquid electrolyte cell. Our results provide new insights into the role of GPE in regulating the solvation sheath of Li+ cations and facilitating the formation of a stable SEI on the Li metal anode.