A Novel Aliphatic Ketone‐Based Solid Polymer Electrolyte with High Salt‐Soluble Ability Enabling Highly Stable Lithium‐Metal Batteries

Abstract Low room temperature ionic conductivity and interfacial incompatibility are the key factors that hinder the practical application of solid polymer electrolyte (SPEs) in lithium metal batteries. Increasing the ability of the SPEs to dissolve and dissociate lithium salt is helpful to enhance ion transport capacity of the SPEs. Herein, ketone groups with high solubility and dissociation ability of lithium salt are introduced into the structural design of SPE, an aliphatic ketone solid polymer electrolyte (KT@SPE) with crosslinking structure is prepared by ultraviolet (UV) polymerization. The prepared KT@SPE shows excellent viscoelastic and possess room temperature ionic conductivity of 10 −4 S cm −1 with 200 wt% lithium bis((trifluoromethyl)sulfonyl)azanide (LiTFSI). Thanks to the contribution of high ion transport capacity, construction of multi‐hydrogen bonds network structure of KT@SPE and a wettability of controlling residual dimethyl sulfoxide (DMSO) solvent to the interface, the assembled symmetrical Li cell realizes stable cycling for over 2000 h at 0.15 mA cm −2 . Moreover, LiFePO 4 cell achieves stable long cycle at 5C and enable Li/KT@SPE 3 /LiFe 0.6 Mn 0.4 PO 4 cell operates at 4.4 V. This work not only provides a design strategy for preparing novel solid polymer electrolytes, but also exhibits the excellent application potential of aliphatic ketone‐based polymer electrolyte in solid‐state lithium batteries at high current density and high voltage.