Localized gelation cellulose separators enable dendrite-free anodes for future zinc-ion batteries

Abstract

The safety, adaptability, and eco-friendliness of zinc-ion batteries have recently been drawing increased attention. However, zinc-ion batteries suffer from irregular interfacial kinetics and uncontrolled Zn²⁺ deposition. Herein, a novel localized gelation separator (LGS) with low-cost natural cellulose separators has been developed, prepared via a green chemistry process. The LGS can “intelligently” select the deposition site through the updated separator/anode interface due to the repulsion between non-gelation regions and anodes. The solvation shell of ZnSO₄ is altered due to the involvement of cellulose, as confirmed by X-ray diffraction patterns, Raman spectra and ab initio molecular dynamics calculations, where the interfacial transfer of Zn²⁺ is regulated and the activity of water is reduced. A novel linearly increasing polarization was observed using electrochemical impedance spectroscopy, revealing smooth interface kinetics and charge-transfer impedance. With those benefits, the zinc symmetric cell shows stable cyclability for more than 1200 h even at 20 mA cm⁻². Superior dendrite suppression was observed using in situ optical microscopy at 20 mA h cm⁻². After 300 cycles, the discharge-specific capacity of the MnO₂ cell with the LGS was 80 mA h g⁻¹. The LGS also showed excellent performance at −20 °C. This LG strategy has broad prospects and provides new ideas for dendrite-free zinc-ion batteries.