Reliable lateral Zn deposition along (002) plane by oxidized PAN separator for zinc-ion batteries

Aqueous zinc ion batteries (AZIBs) are the promising candidate for energy storage where safety and low cost are the major concerns. However, the uneven and random electrodeposition of Zn has become a serious impediment to the deep recharging of AZIBs. Conventional modifications on zinc substrate can promote homogenous zinc deposition initially, but not sustainably. Here, an oxidized polyacrylonitrile (OPAN) membrane with a conjugated planar structure is proposed as a zinc ion battery separator. This separator can continuously regulate the growth of Zn with (002) texture to inhibit dendrites. In addition, the separator has a fast Zn²⁺ ion transfer, which can spontaneously repel SO₄²⁻ and relieve side reactions. As a result, the Zn-symmetric batteries show cycle lifetime of more than 1300 hours at 1 mA cm⁻² and 1 mA h cm⁻², and kept stable for more than 160 hours even at 65% high discharge of depth (DOD). The MnO₂//Zn full celled assembled with an OPAN separator had very little decay for 5000 cycles at 2 A g⁻¹. This work provides a new method for realizing the continuous and uniform deposition of Zn metals, which also provides a new route for batteries with metallic anodes. © 2023 The Author(s). Published by the Royal Society of Chemistry.