A Functional Janus Ag Nanowires/Bacterial Cellulose Separator for High‐Performance Dendrite‐Free Zinc Anode Under Harsh Conditions

Abstract Aqueous zinc‐ion batteries (AZIBs) offer promising prospects for large‐scale energy storage due to their inherent abundance and safety features. However, the growth of zinc dendrites remains a primary obstacle to the practical industrialization of AZIBs, especially under harsh conditions of high current densities and elevated temperatures. To address this issue, a Janus separator with an exceptionally ultrathin thickness of 29 µm is developed. This Janus separator features the bacterial cellulose (BC) layer on one side and Ag nanowires/bacterial cellulose (AgNWs/BC) layer on the other side. High zincophilic property and excellent electric/thermal conductivity of AgNWs make them ideal for serving as an ion pump to accelerate Zn 2+ transport in the electrolyte, resulting in greatly improved Zn 2+ conductivity, deposition of homogeneous Zn nuclei, and dendrite‐free Zn. Consequently, the Zn||Zn symmetrical cells with the Janus separator exhibit a stable cycle life of over 1000 h under 80 mA cm −2 and are sustained for over 600 h at 10 mA cm −2 under 50 °C. Further, the Janus separator enables excellent cycling stability in AZIBs, aqueous zinc‐ion capacitors (AZICs), and scaled‐up flexible soft‐packaged batteries. This study demonstrates the potential of functional separators in promoting the application of aqueous zinc batteries, particularly under harsh conditions.