Co^2+/3+/4+‐Regulated Electron State of Mn‐O for Superb Aqueous Zinc‐Manganese Oxide Batteries

Abstract

Aqueous rechargeable Zn–MnOx batteries are very attractive due to their low‐cost and high energy density. However, Mn(III) disproportionation and Jahn–Teller distortion can induce Mn(II) dissolution and irreversible phase changes, greatly deteriorating the cycling life. Herein, a multi‐valence cobalt‐doped Mn3O4 (Co‐Mn3O4) with high capacity and reversibility, which lies in the multiple roles of the various states of doped cobalt, is reported. The Co2+ doping between the phase change product δ‐MnO2 layer acts as a “structural pillar,” and the Co4+ in the layer can increase the conductivity of Mn4+ and hold the high specific capacity. More importantly, Co ion (Co2+, Co3+) doping can effectively inhibit the Jahn–Teller effect in discharge products and promote ion diffusion. Using X‐ray absorption spectra results and density functional theory modelling, the multiple roles of doped cobalt are verified. Specifically, the Co‐Mn3O4 cathode shows high specific capacity of 362 mAh g–1 and energy density of 463.1 Wh kg–1 at 100 mA g–1. After 1100 cycles at 2.0 A g–1, the capacity retention rate reaches 80%. This work brings a new idea and approach to the design of highly reversible Mn‐based oxides cathode materials for Zn‐ion batteries.

Enhanced Reversible Zinc Ion Intercalation in Deficient Ammonium Vanadate for High-Performance Aqueous Zinc-Ion Battery

“…There is no peaks of Zn 2p in the pristine NVO (Fig. 5 h), while two peaks corresponding to Zn 2p 1/2 (1045.6 eV) and Zn 2p 3/2 (1022.5 eV) appear in the fully discharged state, indicating the intercalation of zinc ions [ 81 ]. The Zn 2p signals in the fully charged state are also detected, which is consistent with the results of ex situ TEM.…”

Oxygen-Defect Enhanced Anion Adsorption Energy Toward Super-Rate and Durable Cathode for Ni–Zn Batteries

“…For example, Chao et al reported that the NiS@ Ni 0.95 Zn 0.05 (OH) 2 used in NZBs has a long life and fast energy response (18.82 kW kg −1 , peak power output of 30 s) [30]. Ionic doping could promote the transmission of ions/electrons and show more redox reactions, thereby contributing to electrochemical performance [31]. Surface modification with the introduction of defects and higher conductivity additives, the surface reactivity and reaction kinetics of electrode materials are improved [32].…”

Aqueous MnV2O6‐Zn Battery with High Operating Voltage and Energy Density

“…[23] Although significant achievements have been made, low capacity for Mnbased and low operating voltages (0.6-0.8 V) for V-based materials still are key bottlenecks for energy density enhancement. [24,25] It charging and enable high operating voltage (≈1.35 V). [26,27] Inspired by this, we, herein, propose to use MnV 2 O 6 (MVO) as a cathode material for high-energy density AZIBs.…”

“…[ 23 ] Although significant achievements have been made, low capacity for Mn‐based and low operating voltages (0.6–0.8 V) for V‐based materials still are key bottlenecks for energy density enhancement. [ 24,25 ]…”