An Ion‐Sieving Janus Separator toward Planar Electrodeposition for Deeply Rechargeable Zn‐Metal Anodes

Abstract

Abstract The irregular and random electrodeposition of zinc has emerged as a non‐negligible barrier for deeply rechargeable aqueous zinc (Zn)‐ion batteries (AZIBs), yet traditional texture regulation of the Zn substrate cannot continuously induce uniform Zn deposition. Here, a Janus separator is constructed via parallelly grown graphene sheets modified with sulfonic cellulose on one side of the commercial glass fiber separator through the spin‐coating technique. The Janus separator can consistently regulate Zn growth toward a locked crystallographic orientation of Zn(002) texture to intercept dendrites. Furthermore, the separator can spontaneously repel SO 4 2− and anchor H + while allowing effective transport of Zn 2+ to alleviate side reactions. Accordingly, the Zn symmetric cell harvests a long‐term lifespan over 1400 h at 10 mA cm −2 /10 mAh cm −2 and endures stable cycling over 220 h even at a high depth of discharge (DOD) of 56%. The Zn/carbon nanotube (CNT)–MnO 2 cell achieves an outstanding capacity retention of 95% at 1 A g −1 after 1900 cycles. Furthermore, the Zn/NH 4 V 4 O 10 pouch cell with a Janus separator delivers an initial capacity of 178 mAh g −1 and a high capacity retention of 87.4% after 260 cycles. This work provides a continuous regulation approach to achieve crystallographic homogeneity of the Zn anode, which can be suitable for other metal batteries.