Although alkaline zinc-manganese dioxide batteries have dominated the primary battery applications, it is challenging to make them rechargeable. Here we report a high-performance rechargeable zinc-manganese dioxide system with an aqueous mild-acidic zinc triflate electrolyte. We demonstrate that the tunnel structured manganese dioxide polymorphs undergo a phase transition to layered zinc-buserite on first discharging, thus allowing subsequent intercalation of zinc cations in the latter structure. Based on this electrode mechanism, we formulate an aqueous zinc/manganese triflate electrolyte that enables the formation of a protective porous manganese oxide layer. The cathode exhibits a high reversible capacity of 225 mAh g⁻¹ and long-term cyclability with 94% capacity retention over 2000 cycles. Remarkably, the pouch zinc-manganese dioxide battery delivers a total energy density of 75.2 Wh kg⁻¹. As a result of the superior battery performance, the high safety of aqueous electrolyte, the facile cell assembly and the cost benefit of the source materials, this zinc-manganese dioxide system is believed to be promising for large-scale energy storage applications.

A lot of attention has been paid to Li–O₂ batteries in recent years, due to the huge potential specific energy and energy density, and they are extensively studied around the world. Much advance has been achieved, however, the fundamental understanding is still insufficient and challenges remain. Here, we provide a specific perspective on the development of non-aqueous Li–O₂ batteries excluding those with aqueous, ionic liquid, hybrid, and solid-state electrolytes, because non-aqueous Li–O₂ batteries possess a relatively simple configuration and the research on non-aqueous Li–O₂ batteries is the most active of all Li–O₂ batteries. The discussion will be focused on non-aqueous electrolytes, cathode catalysts, and anodes, and corresponding perspectives are provided at the end.

Layered transition-metal oxides have attracted intensive interest for cathode materials of sodium-ion batteries. However, they are hindered by the limited capacity and inferior phase transition due to the gliding of transition-metal layers upon Na⁺ extraction and insertion in the cathode materials. Here, we report that the large-sized K⁺ is riveted in the prismatic Na⁺ sites of P2-Na_0.612K_0.056MnO₂ to enable more thermodynamically favorable Na⁺ vacancies. The Mn-O bonds are reinforced to reduce phase transition during charge and discharge. 0.901 Na⁺ per formula are reversibly extracted and inserted, in which only the two-phase transition of P2 ↔ P’2 occurs at low voltages. It exhibits the highest specific capacity of 240.5 mAh g⁻¹ and energy density of 654 Wh kg⁻¹ based on the redox of Mn³⁺/Mn⁴⁺, and a capacity retention of 98.2% after 100 cycles. This investigation will shed lights on the tuneable chemical environments of transition-metal oxides for advanced cathode materials and promote the development of sodium-ion batteries.