Ultrahigh‐Loading Manganese‐Based Electrodes for Aqueous Batteries via Polymorph Tuning

Abstract

Manganese‐based aqueous batteries utilizing Mn2+/MnO2 redox reactions are promising choices for grid‐scale energy storage due to their high theoretical specific capacity, high power capability, low‐cost, and intrinsic safety with water‐based electrolytes. However, the application of such systems is hindered by the insulating nature of deposited MnO2, resulting in low normalized areal loading (0.005–0.05 mAh cm−2) during the charge/discharge cycle. In this work, the electrochemical performance of various MnO2 polymorphs in Mn2+/MnO2 redox reactions is investigated, and ɛ‐MnO2 with low conductivity is determined to be the primary electrochemically deposited phase in normal acidic aqueous electrolyte. It is found that increasing the temperature can change the deposited phase from ɛ‐MnO2 with low conductivity to γ‐MnO2 with two order of magnitude increase in conductivity. It is demonstrated that the highly conductive γ‐MnO2 can be effectively exploited for ultrahigh areal loading electrode, and a normalized areal loading of 33 mAh cm−2 is achieved. At a mild temperature of 50 °C, cells are cycled with an ultrahigh areal loading of 20 mAh cm−2 (1–2 orders of magnitude higher than previous studies) for over 200 cycles with only 13% capacity loss.

Aqueous MnO2/Mn2+ electrochemistry in batteries: progress, challenges, and perspectives

“…5g), while other factors, including Mn 2+ concentration, deposition current density and current collector, do not exhibit this effect. 91 In detail, the primary phase changes from the ε-MnO 2 to γ-MnO 2 as the temperature increases from 25 °C to 90 °C, resulting in two orders of magnitude improvement in electronic conductivity (Fig. 5h).…”

“…(g) XRD patterns of the deposited MnO 2 at different temperatures. The pink star, grey triangle, and yellow circle represent e-MnO 2 , g-MnO 2 and graphite, respectively 91. Copyright 2023, Wiley-VCH.…”

“…Copyright 2023, Wiley-VCH. (h) Cell resistance as a function of the deposited capacity of MnO 2 at different temperatures 91. Copyright 2023, Wiley-VCH.Energy & Environmental Science Review…”

High-rate and long-life flexible aqueous rechargeable zinc-ion battery enabled by hierarchical core–shell heterostructures

“…Therefore, the development of high-performance cathode materials is essential to improve the electrochemical performance of ZIBs. Within the last decade, various cathode materials have been reported, which mainly include manganese-based materials (ZnMn 2 O 4 , 13 Mn 3 O 4 , 14 Mn 2 O 3 , 15 MnO 2 16,17 etc. ), vanadium-based materials (VS 2 , 18 VOPO 4 , 19 V 2 O 5 20,21 etc. )…”

An Organic Coordination Manganese Complex as Cathode for High‐Voltage Aqueous Zinc‐metal Battery

“…[1][2][3][4] Among various battery systems, aqueous batteries, particularly the aqueous ZnÀ Mn battery with low cost, sufficient resources and high safety has been considered as one of the most promising scalable energy storage systems. [5,6] The low voltage (1.35 V vs. Zn 2 + /Zn and 1.20 V vs. ZnO/Zn) of traditional ZnÀ Mn battery with manganese oxides as the cathodes in sulfate electrolyte and in alkaline electrolyte limits their energy density and makes the system integration more difficult since more single cells are needed to be combined in series to create higher output voltage. [7][8][9] Furthermore, upon cycling, manganese oxides experience complicated phase transformation processes (e.g.…”