Three-Dimensional-Percolated Ceramic Nanoparticles along Natural-Cellulose-Derived Hierarchical Networks for High Li+ Conductivity and Mechanical Strength

Solid polymer electrolytes for safe lithium batteries are in general flexible and easy to process, yet they have limited ionic conductivity and low mechanical strength. Introducing nano/microsized fillers into polymer electrolytes has been proven effective to address these issues, while formation of a percolated network of fillers for efficient Li⁺ conduction remains challenging. In this work, composite polymer electrolyte with 3D cellulose/ceramic networks is successfully developed using natural cellulose fibers and Li⁺-conducting ceramic nanoparticles. Monodisperse ceramic nanofillers first form interconnected networks driven by the self-assembly of hybrid cellulose fibers. The hierarchical cellulose skeleton provides spatial guidance for ceramic fillers and firmly supports the whole structure. After polymer electrolyte infusion, the resultant hybrid electrolyte affords both 3D continuous Li⁺ pathways for high Li⁺ conductivity and sufficient mechanical strength for dendrite suppression. This cellulose-confined particle percolation approach enables efficient and strong solid electrolytes for lithium batteries.