A major challenge in aqueous zinc‐ion batteries (AZIBs) is the formation of zinc dendrites, resulting from nonuniform Zn deposition and side reactions such as the hydrogen evolution reaction (HER). Dendrite penetration through the separator can cause short circuits. To address these issues, previous studies have focused on modifying the anode, optimizing the electrolyte, or coating the separator. Here, we propose a strategy to suppress dendrite penetration by applying a spray‐coated layer of bulk hexagonal boron nitride (h‐BN) on one side of the separator surface, forming a Janus separator (BN@GF). Benefiting from its excellent insulating and mechanical properties, h‐BN inhibits charge transfer and effectively suppresses dendrite growth. In addition, the hydrophobicity of BN@GF restricts the transport of free water molecules, thereby mitigating HER. A symmetric cell employing the BN@GF separator exhibited stable cycling for over 1750 h at 5 mA cm –2 and 1 mAh cm −2 . In a full‐cell configuration using V 2 O 5 as the cathode, the BN@GF‐based cell retained 63.5% of its initial capacity after 2500 cycles at 15 A g −1 . Overall, this study demonstrates a simple and effective separator modification method using h‐BN to prevent dendrite penetration, and significantly enhance the cycling stability of AZIBs.
Jo et al. (Thu,) studied this question.