Ultra-high xylan content solid-state ionic conductors with mechanical excellence

Solid-state ionic conductors are integral to flexible electronics, addressing the shortcomings of hydrogels and ionic liquid-based ionic gels. However, the current reliance on petroleum-based materials challenges environmental conservation and sustainable development. Biomass-based solid-state ionic conductors present a viable solution to these concerns but often fall short in mechanical performance. Among various available biomass, xylan is a kind of hemicellulose widely present in plant cell walls with exceptional physicochemical attributes. To solve the problems above, we proposed a high-xylan-content scheme to design a solid-state ionic conductor that leveraged the deep eutectic solvents (DES)-mediated dissolution of xylan to help convert this surplus into high-value-added material for flexible electronics. With the poly(LiTFSI-Acrylic Acid(AA)) DES network containing up to 60 wt% xylan, our ultra-high xylan content liquid-free lithium-salt elastomers (LFLSEs) showed outstanding mechanical performance, with the strain at break of 2604 %, the tensile strength of 10.38 MPa, and the toughness up to 156.02 MJ·m^-3. In addition, the LFLSEs also displayed promising ionic conductivity (3.70 × 10^-4 S m^-1, 25 °C), self-healing properties, and transparency, verifying our approach. The development of LFLSEs facilitates the practical exploration of xylan and contributes to advancements in biomass-based liquid-free ionic conductors.