Ultrathin solid polymer electrolyte enabling mechanically-strong energy storing fiber reinforced composites

Abstract

Structural batteries attract enormous research interest due to their advantages of integrated energy storage function in structure. Superior to the co-cured composite structural batteries based on glass fiber supported/reinforced liquid/low-strength polymer electrolyte, enhanced mechanical strength of solid polymer electrolyte would enable the facile fabrication of composite structural batteries through layer-by-layer stack up of composites and solid-state batteries. This work encloses a mechanically strong and self-supportive solid polymer electrolyte with a tensile strength of 9.28 MPa, significantly superior to the traditional PEO (Lithium salt) electrolyte. Systematic analysis of phase-microstructure-mechanical/electrochemical properties relationship of SPE with different fluoroethylene carbonate (FEC) amounts helps to find out a solid polymer electrolyte (SPE) with satisfactory ionic conductivity (0.35 × 10−4 S/cm) and high electrochemical stability window (4.6 V vs Li/Li+), based on which dimension-adaptable and mechanically-strong energy storing laminates which have high tensile strength of 343 MPa, tensile modulus of 30.6 GPa, flexural strength of 308 MPa, and high impact resistance have been successfully fabricated. The most surprising result is a capacity retention of as high as 67% of the original capacity in the 1st cycle and stable cycling of composite structural batteries over 50 cycles for the failed tensile sample, which points out its potential application in emergency rescue. We believe this work not only presents a facile method to fabricate solid polymer electrolytes but demonstrates the potential of this solid polymer electrolyte in facile fabrication of mechanically-strong composite structural batteries.