Ultrathin Surface Coating of Nitrogen‐Doped Graphene Enables Stable Zinc Anodes for Aqueous Zinc‐Ion Batteries

Abstract

Owing to the high volumetric capacity and low redox potential, zinc (Zn) metal is considered to be a remarkably prospective anode for aqueous Zn‐ion batteries (AZIBs). However, dendrite growth severely destabilizes the electrode/electrolyte interface, and accelerates the generation of side reactions, which eventually degrade the electrochemical performance. Here, an artificial interface film of nitrogen (N)‐doped graphene oxide (NGO) is one‐step synthesized by a Langmuir–Blodgett method to achieve a parallel and ultrathin interface modification layer (≈120 nm) on Zn foil. The directional deposition of Zn crystal in the (002) planes is revealed because of the parallel graphene layer and beneficial zincophilic‐traits of the N‐doped groups. Meanwhile, through the in situ differential electrochemical mass spectrometry and in situ Raman tests, the directional plating morphology of metallic Zn at the interface effectively suppresses the hydrogen evolution reactions and passivation. Consequently, the pouch cells pairing this new anode with LiMn2O4 cathode maintain exceptional energy density (164 Wh kg−1 after 178 cycles) at a reasonable depth of discharge, 36%. This work provides an accessible synthesis method and in‐depth mechanistic analysis to accelerate the application of high‐specific‐energy AZIBs.

Highly reversible zinc metal anodes enabled by protonated melamine

“…8 Moreover, the high Zn 2+ conductivity of ZnF 2 is benecial for inducing Zn 2+ ion diffusion and thus uniform Zn deposition. Other surface coating layers including ZnS, 9 nitrogen-doped graphene, 10 MXenes, 11 and so on 12,13 have also been reported. However, the lack of self-repairability and high manufacturing costs should not be overlooked, which hinder their large-scale applications.…”

Interfacial Engineering Strategy for High-Performance Zn Metal Anodes

“…Therefore, the specific crystallographic structure exposed in parallel with the current collector can induce the deposition of metallic Zn, which may facilitate the stable stripping/plating of Zn in a mild electrolyte [ 73 ]. In addition, the specific crystallographic structure can induce a flat Zn deposition morphology, which reduces the contact area between the electrolyte and Zn anode during cycling and effectively suppresses the growth of dendrites and generation of by-products [ 74 ] (Fig. 2 f).…”

“…On the low lattice mismatch interface composed of well-arranged graphene sheets, a more uniform and compact thin plate parallel to the substrate was produced, and the newly deposited Zn layer adhered to the surface of the Zn formed in the first stage to produce a uniform metallic Zn coating. Xie et al [ 74 ] used the Langmuir–Blodgett method to synthesize an artificial interfacial film of N-doped GO (NGO) in one step and obtained an ultrathin and parallel interfacial layer to modify the Zn anode (Fig. 4 d).…”

“…g Schematic illustration of Zn plating on a bare ZF and NGO@Zn electrode. Copyright 2021 Wiley-VCH [ 74 ]. h Schematic illustration of a Zn@C film and SEM images of the Zn and Zn@C. i Stripping/plating performance of Zn and Zn@C cells at 1 mA cm −2 with 1 mAh cm −2 .…”

Eliminating Stubborn Insulated Deposition by Coordination Effect to Boost Zn Electrode Reversibility in Aqueous Electrolyte

“…However, ZIBs face a series of severe challenges especially for zinc anodes, including dendrite growth and related parasitic reactions caused by free water (such as HER and by-product) ( Yang et al, 2020 ; Sun H et al, 2021 ). Many methods have been reported to improve the performance of ZIBs by inhibiting hydrogen evolution or dendrite in aqueous electrolytes and proved to be effective, such as electrolyte additives ( Soundharrajan et al, 2020 ; Guo et al, 2021 ; Hao et al, 2021 ; Guan et al, 2022 ), artificial SEI layers ( Hao et al, 2020 ; Di et al, 2021 ; Hong et al, 2021 ; Shin et al, 2021 ), and zinc anode modification ( Yang et al, 2021 ; Zhang et al, 2021 ; Zhang et al, 2021 ; Zhou et al, 2021 ). Nevertheless, the side reactions between Zn and aqueous electrolyte have rarely been paid attention to, which closely caused the decreased capacity and poor stability of the battery.…”