The reaction mechanisms (RM) during cycling of aqueous rechargeable Zn//MnO₂ batteries (ARZIBs) are still controversially discussed. The present study of different acidic electrolyte compositions (0.9 mM H₂SO₄, 0.5 M MnSO₄, 2 M ZnSO₄, 2 M ZnSO₄+0.5 M MnSO₄) and their pH behaviour is therefore designed as an alternative approach to investigate the RM. In operando pH tracking during cycling shows periodic pH changes for each electrolyte, highlighting the role of the pH‐relevant ions OH⁻ and H⁺ in the chemical processes, the major influence of MnO₂ deposition/dissolution mechanisms and the buffering behaviour of the zinc hydroxide sulphate (ZHS) precipitation. Innovative coupled cyclic voltammetry (CV) and pH measurements can link CV redox peaks to a pH change and a corresponding chemical reaction. It was found that a Zn²⁺ (de‐)intercalation has little or no influence on the capacity. The cycling of the SO₄²⁻‐free electrolyte 2 M Zn(CF₃SO₃)₂ underlines the pH‐dependant behaviour of the chemical processes. The results can contribute to the debate of RMs in ARZIBs and other aqueous battery chemistries by introducing a novel measurement technique.

Considering the literature for aqueous rechargeable Zn//MnO₂ batteries with acidic electrolytes using the doctor blade coating of the active material (AM), carbon black (CB), and binder polymer (BP) for the positive electrode fabrication, different binder types with (non-)aqueous solvents were introduced so far. Furthermore, in most of the cases, relatively high passive material (CB+BP) shares ~30 wt% were applied. The first part of this work focuses on different selected BPs: polyacrylonitrile (PAN), carboxymethyl cellulose (CMC), styrene butadiene rubber (SBR), cellulose acetate (CA), and nitrile butadiene rubber (NBR). They were used together with (non-)aqueous solvents: DI-water, methyl ethyl ketone (MEK), and dimethyl sulfoxide (DMSO). By performing mechanical, electrochemical and optical characterizations, a better overall performance of the BPs using aqueous solvents was found in aqueous 2 M ZnSO₄ + 0.1 M MnSO₄ electrolyte (i.e., BP LA133: 150 mAh·g⁻¹ and 189 mWh·g⁻¹ @ 160 mA·g⁻¹). The second part focuses on the mixing ratio of the electrode components, aiming at the decrease of the commonly used passive material share of ~30 wt% for an industrial-oriented electrode fabrication, while still maintaining the electrochemical performance. Here, the absolute CB share and the CB/BP ratio are found to be important parameters for an application-oriented electrode fabrication (i.e., high energy/power applications).

For large‐scale energy‐storage systems, the aqueous rechargeable zinc–manganese dioxide battery (ARZMB) attracts increasing attention due to its excellent advantages such as high energy density, high safety, low material cost, and environmental friendliness. Still, the reaction mechanism and its influence on the electrolyte's pH are under debate. Herein, a pH buffer concept for ARZMB electrolytes is introduced. Selection criteria for pH buffer substances are defined. Different buffered electrolytes based on a zinc salt (ZnSO₄, Zn(CH₃COO)₂, Zn(CHOO)₂), and pH buffer substances (acetic acid, propionic acid, formic acid, citric acid, 4‐hydrobenzoic acid, potassium bisulfate, potassium dihydrogen citrate, and potassium hydrogen phthalate) are selected and compared to an unbuffered 2 mZnSO₄reference electrolyte using titration, galvanostatic cycling with pH tracking, and cyclic voltammetry. By adding buffer substances, the pH changes can be reduced and controlled within the defined operating window, supporting the Mn²⁺/MnO₂deposition/dissolution mechanism. Furthermore, the potential plateau during discharge can be increased from ≈1.3 V (ZnSO₄) to ≈1.7 V (ZnSO₄ + AA) versus Zn/Zn²⁺and the energy retention from ≈30% after 268 cycles (ZnSO₄) to ≈86% after 494 cycles (ZnSO₄ + AA). Herein, this work can serve as a basis for the targeted design of long‐term stable ARZMB electrolytes.

The energy transition is only feasible by using household or large photovoltaic powerplants. However, efficient use of photovoltaic power independently of other energy sources can only be accomplished employing batteries. The ever-growing demand for the stationary storage of volatile renewable energy poses new challenges in terms of cost, resource availability and safety. The development of Lithium-Ion Batteries (LIB) has been tremendously pushed by the mobile phone industry and the current need for high-voltage traction batteries. This path of global success is primarily based on its high energy density. Due to changing requirements, other aspects come to the fore that require a rebalancing of different technologies in the “Battery Ecosystem”. In this paper we discuss the evolution of zinc and manganese dioxide-based aqueous battery technologies and identify why recent findings in the field of the reaction mechanism and the electrolyte make rechargeable Zn-MnO₂ batteries (ZMB), commonly known as so-called Zinc-Ion batteries (ZIB), competitive for stationary applications. Finally, a perspective on current challenges for practical application and concepts for future research is provided. This work is intended to classify the current state of research on ZMB and to highlight the further potential on its way to the market within the “Battery Ecosystem”, discussing key parameters such as safety, cost, cycle life, energy and power density, material abundancy, sustainability, modelling and cell/module development.

Aqueous zinc ion batteries are considered to be one of the most promising battery types for stationary energy storage applications. Due to their aqueous electrolyte, they are inherently safe concerning flammability and environmentally friendly. In this work, the strong influence of the particle size of manganese sesquioxide on the performance of the battery is investigated. Ball milling was used to decrease the particle diameter. The resulting powders were used as active material for the cathodes, which were assembled in coin cells as full cells together with zinc foil anodes and aqueous electrolyte. It was shown that about one third of the original particle size can nearly triple the initial capacity when charged with constant current and constant end-of-charge voltage. Additionally, smaller particles were found to be responsible for the collapse of capacity at high current densities. By means of electrochemical impedance spectroscopy, it was shown that particle size also has a large impact on the internal resistance. Initially, the internal resistance of the cells with small particles was about half that of those with big particles, but became larger during cycling. This reveals accelerated aging processes when the reactive surface of the active material is increased by smaller particles.

Electrolytic zinc manganese dioxide batteries (ZMB) are promising alternatives to lithium-ion systems due to their cost-effectiveness, material abundance, and safety, but their adoption is hindered by challenges in energy density and stability. To overcome these hurdles, a deeper understanding of the underlying electrochemical processes is required. This study investigates the role of acetate and sulfate anions in electrolyte performance, focusing on pH buffering capacity and complexation effects at the electrode interface. A thermodynamic model was developed to simulate speciation and reaction equilibria, highlighting that proton transport is the rate-limiting step in sulfate-based electrolytes. Acetate-containing electrolytes exhibited superior buffering capacity and facilitated proton-coupled electron transfer, leading to enhanced manganese dioxide deposition at moderate pH levels. For the first time, a systematic study was conducted in which sulfate was progressively substituted by acetate while maintaining consistent pH conditions. Although acetate ions enable cyclability under mild pH conditions, their strong complexation with Mn³⁺ promotes manganese diffusion into the electrolyte, ultimately reducing reversibility as acetate content increases. Moreover, contrary to common assumptions, acetate anions do not inherently enhance anode stability under identical pH conditions. These insights provide a foundation for optimizing electrolyte design to overcome the limitations of zinc-manganese dioxide batteries.