Inhibition of Zinc Dendrite Growth by WC-Cellulose Separators for High-Performance Zinc-Ion Batteries

The strategies developed to achieve a stable and dendrite-free Zn anode in aqueous zinc-ion batteries, such as constructing an artificial solid–electrolyte interface, modifying the electrolyte and designing a versatile separator, have not been able to meet the requirements for large-scale commercialization due to the complex preparation process and high manufacturing costs. Here, we fabricated a WC-cellulose nanofiber (WCCNF) composite separator with the advantages of cost-efficiency and simplified preparation by a facile solution-casting method for a dendrite-free Zn anode. The fabricated WCCNF separator can efficiently lower the Zn nucleation overpotential, homogeneously the Zn nucleation sites, postpone surface corrosion, promote the uniform Zn deposition, and finally realize the high-performance Zn anode. Consequently, compared with the pure CNF separator, the WCCNF separator vastly extends the cycling lifespan of the Zn∥Zn symmetric cell to 1200 h at 1 mA·cm–2/0.5 mA h·cm–2 and 1000 h at 5 mA·cm–2/1.25 mA h·cm–2. Moreover, using (NH4)2V10O25·8H2O (NVO) as the cathode material, the full cell with the WCCNF separator shows a superior discharge capacity of 132 mA h·g–1 with a capacity retention of 85.2% after 500 cycles at 3 A·g–1, whereas the one with CNF rapidly degrade the capacity to 30 mA h·g–1, indicating the excellent cycling reversibility and stability of the Zn anode endowed by the WCCNF separator. Benefiting from the merits of WCCNF in the reversibility of Zn plating/stripping, the Zn∥NVO pouch cell exhibits a high discharge capacity of 121.6 mA h·g–1 with a high capacity retention of 84.4% after 50 cycles at 0.5 A·g–1. This work provides a low-cost and multifunctional cellulose-based separator for the large-scale commercialization of high-performance AZIBs.