Proton Inserted Manganese Dioxides as a Reversible Cathode for Aqueous Zn-Ion Batteries

Abstract

Recent achievements of aqueous Zn-ion batteries have aroused widespread attention and call for an urgent demand on the development of potential cathode materials. In this work, we developed the proton inserted manganese dioxides (H x Mn2O4) as a cycle-stable cathode material for aqueous Zn-ion batteries. The porous H x Mn2O4 microspheres were derived from the ZnMn2O4 templates via a cation exchange method. Material characterization revealed the distinctive crystal structure with extensive insertion of H+ ions inside the tunnel of MnO6 octahedrons. Compared with the ZnMn2O4, the H x Mn2O4-based Zn-ion batteries delivered an initial capacity of 281.0 mAh/g at 100 mA/g and maintained at 133.4 mAh/g after 1000 cycles at 1000 mA/g. Moreover, a high energy density of 391.6 Wh/kg was realized at 139.4 W/kg. Ex-situ XRD investigation demonstrated the synergistic and reversible insertion/extraction of H+ and Zn2+ ions in the H x Mn2O4 cathode during the charge/discharge process. GITT measurement further verified the fast diffusion kinetics of the Zn2+ ions in the H x Mn2O4 microspheres. The application of the spinel-type H x Mn2O4 cathode would promote the follow-up research on advanced electrode materials for long-life span Zn-ion batteries.

Defect Engineering in Manganese‐Based Oxides for Aqueous Rechargeable Zinc‐Ion Batteries: A Review

“…Wu et al synthesized proton‐inserted manganese dioxides by extracting Zn 2+ ions from the spinel structure of ZnMn 2 O 4 followed by inserting H + ions. [ 78 ] The proton‐inserted manganese dioxides were characterized by the special crystal structure with enough H + insertion into the MnO 6 octahedrons. The Zn 2+ ions diffusion in the spinel of MnO 6 octahedrons becomes easy after incorporating H + into the MnO 2 host.…”

“…Reproduced with permission. [ 78 ] Copyright 2020, American Chemical Society. b) Structural illustration of the as‐prepared Na 0.44 Mn 2 O 4 ·1.5H 2 O. Reproduced with permission.…”

“…[ 77 ] Wu et al developed a proton inserted manganese dioxide as a cathode with good cyclic life for aqueous ZIB using a cation exchange method. [ 78 ] Using ZnMn 2 O 4 as the template, H + from H 2 SO 4 solution was applied to replace Zn 2+ ions in ZnMn 2 O 4 . The ions exchange process of Zn 2+ ions with H + ions was motivated by the Jahn−Teller disproportionation reaction of the Mn 3+ ions along with the distortion of ZnO 4 tetragonal.…”

“…Wu and co‐workers reported a proton inserted manganese dioxide for ZIB application. [ 78 ] The introduction of H + into the MnO 2 framework could facilitate the Zn 2+ diffusion in spinel frameworks of MnO 6 . Thus, high Zn 2+ diffusivity coefficients (10 −11 −10 −7 cm 2 s −1 ) were recorded for the material, and due to such factors, the material was able to demonstrate fast Zn 2+ storage kinetics.…”

Self-assembled α-MnO2 urchin-like microspheres as a high-performance cathode for aqueous Zn-ion batteries

“…Typically, AZIBs consist of an intercalation-type cathode, a zinc metal anode and a Zn 2+ -based aqueous electrolyte, which demonstrate attractive features of large theoretical capacity (820 mA h g −1 and 5855 mA h cm −3 ), wide working potential window (0-2 V), reversible plating/stripping of Zn, high safety, environmental friendliness, low cost and facile manufacturing process [1][2][3][4]. Since Kang's group [5] [6][7][8][9]. Among them, the α-MnO 2 -based AZIBs exhibit the highest specific capacity of more than 380 mA h g −1 , long-term reversibility and extraordinary rate capability, which benefit from their 2×2 tunnel structure with corner-sharing double MnO 6 octahedra chains [10].…”