Multifunctional polymer bottlebrush-based gel polymer electrolytes for lithium metal batteries

Abstract Solid-state polymer electrolytes (SPEs) are considered to be promising in solving the safety problems caused by the leakage of liquid electrolytes and the growth of lithium dendrite. However, the major challenge to realize practical applications is how to develop high-performance SPEs with superb interfacial contact, high ionic conductivity at room temperature, and mechanical robustness. Herein, a novel kind of multifunctional polymer bottlebrush (BC-g-PEGM)-based gel polymer electrolytes (BC-g-PEGM-GPEs) is designed and prepared. The as-obtained BC-g-PEGM-GPEs integrate features of BC backbone-strengthened nanonetwork, polymer brush-enhanced interfacial compatibility, and abundant lithium-ion conducting domains from polymer brushes. As a result, BC-g-PEGM-GPEs exhibit good mechanical properties (Young's modulus = 5.0 MPa, toughness = 316.7 KJ/m3) and high ionic conductivity of 2.7 × 10−4 S/cm at room temperature. The Li/Li symmetric batteries with BC-g-PEGM-GPEs show stable cycling over 1200 h at a current density of 0.5 mA/cm2. Furthermore, both Li/LiFePO4 and Li/Li4Ti5O12 batteries using BC-g-PEGM-GPEs exhibit desirable cycling stability and good rate performance at room temperature, suggesting that this new GPE system has great potential for practical applications in lithium metal batteries.