A High‐Potential Anion‐Insertion Carbon Cathode for Aqueous Zinc Dual‐Ion Battery

Abstract

Aqueous dual‐ion batteries (DIBs) are promising for large‐scale energy storage due to low cost and inherent safety. However, DIBs are limited by low capacity and poor cycling of cathode materials and the challenge of electrolyte decomposition. In this study, a new cathode material of nitrogen‐doped microcrystalline graphene‐like carbon is investigated in a water‐in‐salt electrolyte of 30 m ZnCl2, where this carbon cathode stores anions reversibly via both electrical double layer adsorption and ion insertion. The (de)insertion of anions in carbon lattice delivers a high‐potential plateau at 1.85 V versus Zn2+/Zn, contributing nearly 1/3 of the capacity of 134 mAh g−1 and half of the stored energy. This study shows that both the unique carbon structure and concentrated ZnCl2 electrolyte play critical roles in allowing anion storage in carbon cathode for this aqueous DIB.

High‐Performance Aqueous Na–Zn Hybrid Ion Battery Boosted by “Water‐In‐Gel” Electrolyte

“…The X‐ray powder diffraction (XRD) spectrum of synthesized CuHCF is shown in Figure a, in which the as‐prepared CuHCF nanoparticles show a high crystallinity degree and all the reflections are indexed as the face‐centered cubic Cu 2 [Fe(CN) 6 ] (PDF #02‐0381). Due to its PBAs layer structure [1] , CuHCF shows outstanding potential for Na and Zn ion storage because monovalent and divalent cations can be facile to be inserted into the PBAs framework [17] . And CuHCF was reported a higher redox voltage by monovalent ion intercalation compared with pristine FeHCF, [ 16 ] suggesting a higher performance.…”

“…To further investigate on the multiple intercalated ions, the electrochemical behaviors of CuHCF cathode were comprehensively investigated by ion exchange membranes (Figure 2d), which can distinguish the storage of cation and anion. Thus, a high intercalation peak of Na + (2.3 V vs Zn/Zn 2+ ) and an intercalation peak of Zn 2+ (1.6 V vs Zn/Zn 2+ ) were obtained by a cation exchange membrane (CEM) covered CuHCF cathode, while reduction peaks at 1.9 and 1.6 V versus Zn/Zn 2+ , Figure 2d were shown by an anion exchange membrane (AEM) covered CuHCF cathode, indicating the de‐intercalation of ZnCl 4 2‐[ 17 ] and Cl −[ 18 ] To further distinguish the (de‐)intercalation of Cl – and ZnCl 4 2− , CV curves in HCl and ZnCl 2 electrolytes were investigated and compared. An obvious pair of redox peaks for the (de‐)intercalation of Cl − was shown in 1 m HCl at 0.7/1.1 V versus Ag/AgCl, and a two reduction peaks at 0.9 and 0 V versus Ag/AgCl in WIS‐ZnCl 2 electrolyte were observed (Figure S5, Supporting Information).…”

Electrochemical Zinc Ion Capacitors: Fundamentals, Materials, and Systems

“…However, chlorine evolution reaction may occur in the ZnCl 2 WIS electrolyte and be responsible for the unstable cycling performance. [ 162 ] Hydrophobic artificial layers coating on the zinc anodes [ 205 ] can suppress water decomposition by reducing the water activity around zinc anodes.…”

“…However, the chlorine evolution reaction may cause poor anodic stability of the ZnCl 2 WIS electrolyte. [ 162 ] More works can devote to develop low‐cost and high electrochemical stable WIS electrolytes.…”

A Review of Emerging Dual‐Ion Batteries: Fundamentals and Recent Advances

“…[ 53 ] A WiSE of 30 m ZnCl 2 was explored in a Zn–nitrogen doped graphene DIB, where this nitrogen doped graphene cathode stored anions in electrical double layers at low potentials, and [ZnCl x ] 2− x ions were reversibly inserted into the graphenic layered structures in a diffusion‐controlled process at high potentials. [ 118 ] The (de)insertion of anions in carbon lattice delivered a high potential plateau at 1.85 V, resulting in a capacity of 134 mAh g −1 . To further maximize the ionic content, expand the anodic stability window, promote dendrite‐free zinc plating/stripping with high columbic efficiency, and enable the reversible anion intercalation in graphite cathode, hybrid WiSEs (HWiSE) or “water‐in‐bisalt” electrolytes (WiBSE) with two kinds of salts dissolved in water have been investigated for Zn–graphite DIBs.…”