Nanoengineered Functional Cellulose Ionic Conductor Toward High- Performance All-Solid-State Zinc-Ion Battery

The rechargeable zinc-ion battery is regarded as a promising candidate for the next-generation energy storage system, however, zinc dendrite growth and hydrogen evolution reaction (HER) have greatly hindered the practical application of the battery. Herein, a functionalized, nano-engineering Zn2+ coordinated carboxylate cellulose solid-state electrolyte (denoted as Zn-CCNF@XG) for zinc-ion battery is constructed through a straightforward approach. According to the experimental and density functional theory (DFT) results of dissociation energy, the notably decreased dissociation energy by -COOH is favorable to Zn2+ de-coordinating and rapid ion-hopping in Zn-CCNF@XG to achieve high ionic conductivity and transference number. More importantly, the engineered molecular channels are beneficial to enlarging the distance between the nanofibril chains, providing a larger space for the movement of Zn2+. Benefiting from the coordination of Zn2+ with -OH in carboxylate cellulose nanofibrils, Zn-CCNF@XG as a good ionic conductor displays a high ionic conductivity of 1.17 x 10-4 S cm-1 and transference number of 0.78. The Zn||NaV3O8 center dot 1.5H2O full cell with Zn-CCNF@XG maintains a capacity retention of 83.46% with a coulombic efficiency of 99.99% after 3000 cycles (1 A g-1). The proposed strategy by introducing a functional group to cellulose nanofibrils effectively avoids the dendrite and HER, providing valuable guidelines for the practical application of zinc-ion batteries. Functionalizing and nano-engineering strategies are utilized to explore cellulose as a novel solid-state Zn2+ conductor (Zn-CCNF@XG). The introduction of -COOH is favorable to Zn2+ rapid ion-hopping with low energy barrier and high ionic conductivity (1.17 x 10-4 S cm-1), showing an efficient and instructive strategy for high ionic conductivity, ionic transference number, and stability of SSEs. image