Achieving High‐Voltage and High‐Capacity Aqueous Rechargeable Zinc Ion Battery by Incorporating Two‐Species Redox Reaction

Abstract

safety, and low cost. [1][2][3][4][5] However, the strong electrostatic interaction with host materials originating from divalent chemistry leads to low output voltage, poor reversibility, and especially sluggish kinetics. Various cathode materials have been developed to navigate these challenges. Currently, the most studied cathode active materials are manganesebased [6][7][8][9] and vanadium-based [10][11][12][13] composites. Nonetheless, relative low operating voltage and poor rate performance remains as issues. To reach the operating voltage of electronic devices, multiple batteries must be connected in series. This practice increases the volume of battery and causes energy loss. Furthermore, poor rate capability limits application of Zn-ion batteries in high-power appliances.The Prussian blue analogues (PBAs) possessing a 3D open framework with large interstitial sites, [4][5][6][7][8][9][10][11][12][13][14][15][16] are considered as a promising host material for reversible Zn-ion intercalation/deintercalation with fast charge/discharge properties and high operational voltage, which is ascribed to its ideal crystal structure and desirable electrochemical properties. [17] Recently, hexacyanometallates with a typical formula of A x M′[M″(CN) 6 ] y ⋅nH 2 O (simply denoted as M′/M″ PBA) are investigated as cathode active materials for aqueous batteries including Li-, Na-, Mg-, Ca-, and Zn-ion batteries, where the A Herein, a two-species redox reaction of Co(II)/Co(III) and Fe(II)/Fe(III) incorporated in cobalt hexacyanoferrate (CoFe(CN) 6 ) is proposed as a breakthrough to achieve jointly high-capacity and high-voltage aqueous Zn-ion battery. The Zn/CoFe(CN) 6 battery provides a highly operational voltage plateau of 1.75 V (vs metallic Zn) and a high capacity of 173.4 mAh g −1 at current density of 0.3 A g −1 , taking advantage of the two-species redox reaction of Co(II)/Co(III) and Fe(II)/Fe(III) couples.Even under extremely fast charge/discharge rate of 6 A g −1 , the battery delivers a sufficiently high discharge capacity of 109.5 mAh g −1 with its 3D opened structure framework. This is the highest capacity delivered among all the batteries using Prussian blue analogs (PBAs) cathode up to now. Furthermore, Zn/CoFe(CN) 6 battery achieves an excellent cycling performance of 2200 cycles without any capacity decay at coulombic efficiency of nearly 100%. One further step, a sol-gel transition strategy for hydrogel electrolyte is developed to construct high-performance flexible cable-type battery. With the strategy, the active materials can adequately contact with electrolyte, resulting in improved electrochemical performance (≈18.73% capacity increase) and mechanical robustness of the solid-state device. It is believed that this study optimizes electrodes by incorporating multi redox reaction species for high-voltage and high-capacity batteries.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.

In Situ Electrochemical Synthesis of MXenes without Acid/Alkali Usage in/for an Aqueous Zinc Ion Battery

“…As the cycle progresses, by the 10 th cycle, broad redox peaks at 0.7/0.3V and 0.5/1.0-1.6 V appear, completely agreeing with the electrochemical behavior of V 2 CT X MXene in the previous study. [11,[29][30][31] Meanwhile, these features that Figure 3. Characterization of phase and structure transition of V 2 CT X MXene during further cycling.…”

“…Figure 4g reviews the rate performance of V-based aqueous zinc batteries reported in recent years. [30,37,39,[44][45][46][47][48][49][50][51][52] Our battery based on V 2 AlC cathode offers an excellent rate performance in aspects of both high capacities at a low current density and high current density toleration. In detail, the highest capacity of about 409.7 mAh g −1 with less than 25 mAh g −1 from the carbon cloth and additives can be obtained at 0.5 A g −1 .…”

Zinc based micro‐electrochemical energy storage devices: Present status and future perspective

“…M, Schematic of Zn//CoFe(CN) 6 MBs based on PAM electrolyte with and without F77, and, N, corresponding galvanostatic charge/discharge curves. (E‐G,L‐N) Reproduced with permission 30,52,55,59,62 . Copyright 2016, 2018, and 2019, Wiley‐VCH.…”

“…The as‐fabricated MBs offered high specific capacity of 100.2 mAh/cm 3 and superior energy density of 195.39 mWh/cm 3 . To explore the new electrolyte for ensuring the mechanic strength of the MBs, Ma et al 62 invented a new‐type electrolyte (Figure 3M,N) of the PAM with poly (ethylene oxide) 53 ‐poly(propylene oxide) 34 ‐poly(ethylene oxide) (F77), which showed a distinct sol‐gel transition feature from 0°C to room temperature accompanied with the state change from aqueous to gel, contributing to the full utilization of the active material. As a result, this Zn//CoFe(CN) 6 MB delivered admirable long‐term cyclability (93.4% after 2000 cycles).…”

Dendrites issues and advances in Zn anode for aqueous rechargeable Zn‐based batteries

“…These features endow the RZBs with the most competitive candidate for powering flexible and wearable devices. In the past decades, tremendous work was devoted to distinguishing a proper cathode for RZBs, manganese‐based oxides, 11,12 vanadium‐based oxides, 13‐15 cobalt‐base oxides, 16,17 molybdenum‐based materials, 18 prussian blue analogous, 19,20 and other materials. The advances in developing those materials broke many stereotypes, realizing high capacity, high voltage platform, and long lifespan 20‐22 .…”