Loosening Zinc Ions from Separator Boosts Stable Zn Plating/Striping Behavior for Aqueous Zinc Ion Batteries

Abstract

Aqueous zinc ion batteries are attracting broad interest in stationary energy storage where low cost, robust security, and satisfactory capacity matter most. However, metal zinc anodes suffer from destructive dendrite issues during repeated charging/discharging process, decreasing the cycle life of batteries. Herein, smoother zinc plating/striping behaviors are achieved by group modification in the structural unit of the polymer separator. Experimental results and theoretical simulations reveal that the polymer skeleton can release zinc ion more easily when modified with carbonylation side groups and contribute to much faster zinc ion transfer capability. Typically, symmetric Zn cells with a thin thickness separator of 21 µm exhibit ultralong cycle life over 2800 h at 1 mA cm−2 within 1 mAh cm−2 and 300 h under a high current density of 5 mA cm−2 within high areal capacity of 3 mAh cm−2. Full cells using a sodium vanadium oxide cathode also show stable reversible charging/discharging performance after 2000 cycles at 3 A g−1. This work is expected to inspire promising strategies in molecular design in polymeric separator toward stabilizing metal anodes beyond this anode itself.

Functionalized Non-Glass Fiber Nanoporous Separator for High-Performance Aqueous Zinc Ion Batteries

“…This modification strategy is applicable to AZIBs, yielding the desired outcomes. On the one hand, researchers often chemically modify functional groups; on the other hand, they will physically modify the original separator with nanomaterials containing rich functional groups . The modified materials can not only form a close bond with the separator substrate through noncovalent interaction but also inhibit the side reaction and increase the zincophilicity through the role of functional groups.…”

“…(b) Mechanism of uniform zinc deposition with modified separators (CCM). Reproduced with permission from ref . Copyright 2023 Elsevier.…”

“…The distinctive chain structure of cellulose, with numerous hydroxyl functional groups in the side chains, offers excellent modifiability. 84 Zhang et al 82 crafted an ultrathin cellulose separator (21 μm thick) by carbonylating a significant number of cellulose hydroxyls, optimizing its functional groups. Electrochemical experiments and theoretical analyses demonstrated that altering the carbonylation of side groups weakened the interaction between the polymer backbone and zinc.…”

Modification of Zinc Anodes by In Situ ZnO Coating for High-Performance Aqueous Zinc-Ion Batteries

“…Therefore, various strategies have been developed to reduce zinc dendrite formation, including the modification of current collectors, the design of anodes, optimization of electrolytes to regulate the solvation structure of Zn 2+ , and the refinement of separators. − Among these, constructing an artificial interphase to suppress water decomposition and regulate Zn plating emerge as key strategies for enhancing the electrochemical properties of zinc-ion batteries, including ex situ and in situ coating approaches . Building a protective layer by ex situ coating inorganics (e.g., TiO 2 , CaCO 3 , graphene, Ag, Al 2 O 3 , ZnF 2 , HfO 2 , Zn 3 (PO 4 ) 2 , Si) or polymer [e.g., poly­(vinyl butyral) (PVB), poly­(vinyl alcohol) (PVA), silk fibroin, polyimide] on the surface of Zn anodes is an attractive method to regulate Zn dendrites by allowing Zn 2+ to transport but blocking water penetration to Zn surfaces.…”

Crystalline MnCO3@Amorphous MnOx Composite as Cathode Material for High-Performance Aqueous Zinc-Ion Batteries

“…Among various rechargeable aqueous batteries, aqueous zinc-ion batteries (AZIBs) have attracted much attention due to their low cost, high safety, environmental friendliness, and simple assembly process. − The electrochemical reaction mechanisms of AZIBs are based on the repeated intercalation/deintercalation of Zn 2+ in the cathode materials. − However, the large radius of Zn 2+ and its hydrated ions can cause deformation or even structural collapse of the electrode materials during Zn 2+ intercalation/deintercalation, which limits the choice and applications of cathode materials for AZIBs. − In addition, the poor conductivity of cathode materials and large electrode polarization during repeated cycling can lead to slow electrochemical kinetics and rapid capacity decay. ,, Therefore, it is imperative to develop cathode materials with excellent Zn 2+ intercalation/deintercalation capability, high reversible capacity, and desired cycling stability. , …”