Characterization of the adhesive properties between structural battery electrolytes and carbon fibers

Structural batteries can simultaneously store electrical energy and carry mechanical load, being similar to both laminated carbon fiber composites and lithium ion batteries. The matrix in a structural battery must both conduct ions and transfer load between the fibers, made possible with a phase-separated combination of a solid polymer and a liquid electrolyte. This leads to a trade-off between the polymer contact creating adhesion and liquid contact creating ionic conductivity. Here we investigate the fiber-matrix adhesion between carbon fibres with different sizing and two different matrix systems, using microbond testing supported by transverse tensile tests. The results show that the mechanical adhesion of the fiber-matrix interface is lower than that of a commercial non-ion conducting polymer matrix but sufficient for structural battery applications.