Recent advances in cellulose-based separators for zinc ion batteries: A review

Aqueous zinc ion batteries (AZIBs) have attracted increasing attention because of their high energy density, excellent safety features, and environmentally friendly properties. The separator plays a crucial role in the battery, greatly influencing its performance and stability. Therefore, the separator for AZIBs has attracted increasing interest in recent years. Glass fiber (GF) is the predominant separator material, and exhibits favorable hydrophilicity and remarkable ionic conductivity. Nevertheless, its internal inhomogeneous pore structure makes it difficult to achieve uniform deposition of zinc ions, while the GF separator is easy to pierce due to its inadequate mechanical properties. In response to these issues, cellulose materials have garnered significant interest owing to their exceptional hydrophilicity, cost-effectiveness, and widespread availability. This review summarizes the potential of cellulose separators to substitute GF separators for AZIBs because of their high porosity, ion mobility number, electrolyte wetting rate, and liquid absorption rate. Different methods for preparing cellulose separators for AZIBs and various strategies to enhance their performance are summarized. The future outlook of cellulose-based separators for ZIBs is also prospected.