Cellulose Nanofiber/Carbon Nanotube‐Based Bicontinuous Ion/Electron Conduction Networks for High‐Performance Aqueous Zn‐Ion Batteries

Abstract

Despite their potential as a next-generation alternative to current state-of-the-art lithium (Li)-ion batteries, rechargeable aqueous zinc (Zn)-ion batteries stilllag in practical use due to their low energy density, sluggish redox kinetics,and limited cyclability. In sharp contrast to previous studies that have mostlyfocused on materials development, herein, a new electrode architecturestrategy based on a 3D bicontinuous heterofibrous network scaffold (HNS)is presented. The HNS is an intermingled nanofibrous mixture composed ofsingle-walled carbon nanotubes (SWCNTs, for electron-conduction channels)and hydrophilic cellulose nanofibers (CNFs, for electrolyte accessibility). Asproof-of-concept for the HNS electrode, manganese dioxide (MnO2) particles,one of the representative Zn-ion cathode active materials, are chosen. TheHNS allows uniform dispersion of MnO2 particles and constructs bicon-tinuous electron/ion conduction pathways over the entire HNS electrode(containing no metallic foil current collectors), thereby facilitating the redoxkinetics (in particular, the intercalation/deintercalation of Zn2+ ions) of MnO2particles. Driven by these advantageous effects, the HNS electrode enablessubstantial improvements in the rate capability, cyclability (without structuraldisruption and aggregation of MnO 2), and electrode sheet-based energy(91 Wh kg electrode−1)/power (1848 W kgelectrode−1) densities, which lie far beyondthose achievable with conventional Zn-ion battery technologies