Rechargeable Manganese Dioxide−Zinc Batteries: A Review Focusing on Challenges and Optimization Strategies under Alkaline and Mild Acidic Electrolyte Media

Abstract

Herein, we have reviewed the recent developments of rechargeable manganese dioxide−zinc (MnO2−Zn) batteries under both alkaline and mild acidic electrolyte systems. The evolution pathway of MnO2−Zn system from Leclanché cell to alkaline primary batteries and from primary to secondary batteries is chronologically depicted. Several adverse phenomena are associated with the reversibility of metallic zinc negative electrode under alkaline (pH 14) electrolyte mediums, and these may include zinc dendrite formation, passivation of electrode surface, shape change of the electrode, zincate crossover through separator and hydrogen evolution upon charging. The MnO2 positive electrode also experiences few performance degrading issues under alkaline mediums; like generation of electrochemically inert phases (Mn3O4 and ZnMn2O4) in the electrode upon deep‐discharge and Mn‐dissolution in the electrolyte. The mitigation measures of these challenges are well documented and systematically analysed. On the invention of zinc‐ion batteries, the MnO2−Zn secondary batteries are assembled under mild acidic (pH 4–6) electrolytes, and eventually, several adverse effects of alkaline systems are drastically nullified. However, recent scientific and technical efforts are coined to address the challenges of large‐scale MnO2−Zn batteries in mild acidic mediums, and formulate the optimization strategies. This review culminates with a few smart designs of MnO2−Zn batteries, whereas, truly path‐breaking concepts are associated with. To the best of our knowledge, it is the first review that covers the entire spectrum of MnO2−Zn system in both alkaline and mild acidic mediums, along with evolution pathways.

Review—Current Collectors for Rechargeable Batteries: State-of-the-Art Design and Development Strategies for Commercial Products

“…In the arena of rechargeable MnO 2 -Zn alkaline batteries, such carbon-based flexible current collectors are frequently used. 54 As an instance, Thong et al developed a flexible thin-film primary MnO 2 -Zn battery (3 V/20 mAh) comprising a twocell stack in series with a flexible carbon current collector. 55 However, such flexible current collectors could be also used in rechargeable alkaline battery chemistries without hampering the electrochemical performances.…”

“…For example, graphene-coated SS and graphene-coated Cu are depicted as suitable current collectors for homogeneous Zn deposition. 54 However, Ni, Ti, SS, graphite, carbon paper, etc are frequently noted as positive current collectors for Zn-ion batteries. 113 Yu et al analysed the electrochemical stability of Ti current collector in aqueous electrolytes, whereas stable passivation layer of TiO 2 protects the Ti substrate from further oxidation.…”

Force Fields for High Concentration Aqueous KOH Solutions and Zincate Ions

“…Many renewable energy technologies rely on aqueous alkaline solutions containing potassium hydroxide (KOH), including fuel cells, electrolyzers, and rechargeable zinc-based batteries. , Aqueous KOH solutions have relatively high ionic conductivity and low cost. In electrochemical devices, the concentration of KOH is often very high, ranging from 4 to 12 M, corresponding to 20–45 wt % KOH.…”

High-Performance and Scalable Aqueous Na-Ion Batteries Comprising a Co-Prussian Blue Analogue Framework Positive Electrode and Sodium Vanadate Nanorod Negative Electrode for Solar Energy Storage

“…Apart from these two matured technologies, alkaline secondary batteries (Ni//Fe, Ni//Zn, MnO 2 //Zn, etc.) and redox-flow batteries are foreseen for solar energy storage. − But, they are under unindustrialized phases. Nominally investigated but environmentally benign aqueous Na-ion batteries are inexpensive alternatives and have enormous potential in solar energy storage applications.…”