Constructing Star-Shaped Compound to Improve the Performance of Cross-Linked Solid Polymer Electrolytes

The star-shaped compound was fabricated by a UV irradiation reaction between trimethylolpropane tris(3-mercaptopropionate) (TMPMP) or pentaerythritol tetrakis(3-mercaptopropionate) (PETMP) with the introduction of poly(ethylene glycol) methacrylate (PEGMA) follow the mechanism of thiol-acrylate click chemistry. Additionally, PETMP or TMPMP is used as the crosslinker in the system, and PEGMA is used as the branch chain of the star-shaped compound. The structure of the compound can be tuned by utilizing different crosslinker combined with varying the molecular weight of PEGMA, effectively. By blending the prepared star-shaped compound into a kind of cross-linked solid polymer electrolytes (SPEs), the mechanical and electrochemical performances of this SPEs are improved simultaneously. In particular, the tensile strength, Young's modulus, elongation at break, tensile toughness, and ionic conductivity at room temperature of the product is 83.9 MPa, 180.4 MPa, 49.9%, 22.6 MJ/m³, and 2.8×10^-5 S/cm, respectively. The discharge capacity of the solid-state lithium metal batteries assembled by the fabricated SPEs reaches 111.5 mAh/g at 0.1C after 100 cycles, indicating nearly 77% of the capacity maintaining.