An ultrathin polymer-based solid-state electrolyte membrane with high conductivity for lithium metal batteries...

Polymer-based solid-state electrolytes offer the advantages of achieving ultrathin thickness through straightforward processing, which is beneficial for improving the energy density of lithium metal batteries. However, significant challenges remain in accelerating Li⁺ transport within polymers at room and low temperatures, as well as in improving the electrolyte/electrode interfacial stability. In this work, a novel approach that combines multifunctional inorganic fillers and plasticizers in solid-state polymer electrolytes (SPEs), resulting in ultrathin solid electrolytes with a thickness of 13 μm and exceptional Li⁺ transport performance at room temperature and low temperature. Notably, the optimized composite solid-state electrolytes exhibit a room-temperature ionic conductivity of 2.41 × 10^-4 S cm^-1, a Li⁺ transference number of 0.54, and negligible thermal shrinkage at 200 °C. The analytical results reveal that -SO₃Li modification on the surface of alumina nanoparticle works synergistically with the -CN group of succinonitrile to enhance Li⁺ ionic conductivity, while also promoting the formation of a stable solid-state electrolyte interphase (SEI). Furthermore, lithium metal batteries utilizing the ultrathin composite electrolyte paired with the NCM811 cathode demonstrate an operating temperature range of -25 °C to 60 °C. This work presents an innovative strategy that facilitates the cost-effective manufacturing of SPEs, and broadens their application in lithium metal batteries.