Cobalt–Nickel Double Hydroxide toward Mild Aqueous Zinc‐Ion Batteries

Abstract

Transition metal layered double hydroxides (LDHs) are widely used as high‐performance cathode materials for aqueous alkaline zinc (Zn) batteries. Yet, the strongly alkaline electrolytes may lead to undesirable rechargeability of the alkaline devices and environmental issues. Herein, as a research prototype, CoNi LDH material is designed with abundant H vacancies using electrochemical methods (denoted as CoNi LDH(v)). As a Zn‐ion battery cathode, CoNi LDH(v) exhibits promising electrochemical performances in mild ZnSO4 electrolyte, such as a good specific capacity of 185 mAh g−1 at the current density of 1.2 A g−1, a high average discharge potential of 1.6 V versus Zn2+/Zn, and a large energy density of 296.2 Wh kg−1 at the power density of 1894 W kg−1, outperforming most of the cathode materials for aqueous Zn‐ion batteries. Experimental and computational results indicate that the introduced H vacancies in the double hydroxide matrix induce the improved electronic conductivity and cation adsorption thermodynamics, endowing the double hydroxides with good electrochemical activity for reversible cation insertion. Structural and spectroscopy studies identify that CoNi LDH(v) experiences reversible H+/Zn2+ co‐intercalation mechanism in an aqueous ZnSO4 electrolyte. As far as it is known, it is the first report on transition‐metal‐based double hydroxides used for mild aqueous Zn‐ion batteries.

Nature of Zinc‐Derived Dendrite and Its Suppression in Mildly Acidic Aqueous Zinc‐Ion Battery

“…[4][5][6] The drawback is low operation voltage due to high standard electrode potential of Zn (Zn 2+ /Zn: −0.76 V vs the standard hydrogen electrode), while used cathode materials usually deliver high capacity over 300 mAh g −1 that can compensate for the low operation voltage. [7][8][9] Readiness of air-handling for cell fabrication and abundance of zinc resource are the great opportunity to place ZIBs as next-generation power sources for large-scale ESSs. Apart from superior cell performance even at high rates and readiness of handling, ZIBs suffer from zinc dendrite formation on the surface of zinc metal anode, which significantly degrades battery performance [4,[10][11][12][13][14] and, eventually, leads to shortened cycle life due to internal circuit of ZIBs by the dendrite.…”

Highly exposed surface pore-edge FeNx sites for enhanced oxygen reduction performance in Zn-air batteries

“…3e. The charge transfer resistance ( R ct ) value of SPE-FeN x -HPNC is smaller than that of Fe 3 C-NC and FeN x -HPNC, indicating that electron transfer rate of the electrode was enhanced in SPE-FeN x -HPNC, 51 accelerating the kinetic process for ORR.…”

Engineering NiCo2S4 nanoparticles anchored on carbon nanotubes as superior energy-storage materials for supercapacitors

“…In recent years, various works are reported about nickel-cobalt layered double hydroxide, transition metal oxides and suldes for pseudocapacitors. [21][22][23] Researches indicate that, compared single-component suldes, binary metal suldes have higher specic capacity owing to their more redox reactions. 24,25 Nickel-cobalt sulde possess the fast Faraday reaction from the synergistic reaction of nickel and cobalt and it is reckoned as a promising candidate with enhanced electrocapacitive property toward energy-storage devices.…”