Rechargeable zinc–manganese dioxide batteries that use mild aqueous electrolytes are attracting extensive attention due to high energy density and environmental friendliness. Unfortunately, manganese dioxide suffers from substantial phase changes (e.g., from initial α-, β-, or γ-phase to a layered structure and subsequent structural collapse) during cycling, leading to very poor stability at high charge/discharge depth. Herein, cyclability is improved by the design of a polyaniline-intercalated layered manganese dioxide, in which the polymer-strengthened layered structure and nanoscale size of manganese dioxide serves to eliminate phase changes and facilitate charge storage. Accordingly, an unprecedented stability of 200 cycles with at a high capacity of 280 mA h g−1 (i.e., 90% utilization of the theoretical capacity of manganese dioxide) is achieved, as well as a long-term stability of 5000 cycles at a  utilization of 40%. The encouraging performance sheds light on the design of advanced cathodes for aqueous zinc-ion batteries.

Zinc metal featuring low cost, high capacity, low potential, and environmental benignity is an exciting anode material for aqueous energy storage devices. Unfortunately, the dendrite growth, limited reversibility, and undesired hydrogen evolution hinder its application. Herein, we demonstrate that MOF ZIF-8 annealed at 500 C (ZIF-8-500) can be used as a host material for high-efficiency (approximately 100%) and dendrite-free Zn plating and stripping because of its porous structure, trace amount of zinc in the framework, and high over-potential for hydrogen evolution. The Zn@ZIF-8-500 anode (i.e., ZIF-8-500 pre-plated with 10.0 mAh cm À2 Zn) is coupled with an activated carbon cathode or an I 2 cathode to form a hybrid supercapacitor or a rechargeable battery, respectively. The supercapacitor delivers a high energy density of 140.8 Wh kg À1 (normalized to the mass of active materials in electrodes) while retaining 72% capacity over 20,000 cycles, and the battery shows a long life of 1,600 cycles.

Rechargeable batteries have been used to power various electric devices and store energy from renewables, but their toxic components (namely, electrode materials, electrolyte, and separator) generally cause serious environment issues when disused. Such toxicity characteristic makes them difficult to power future wearable electronic devices. Now an environmentally friendly and highly safe rechargeable battery, based on a pyrene-4,5,9,10-tetraone (PTO) cathode and zinc anode in mild aqueous electrolyte is presented. The PTO-cathode shows a high specific capacity (336 mAh g ) for Zn storage with fast kinetics and high reversibility. Thus, the PTO//Zn full cell exhibits a high energy density (186.7 Wh kg ), supercapacitor-like power behavior and long-term lifespan (over 1000 cycles). Moreover, a belt-shaped PTO//Zn battery with robust mechanical durability and remarkable flexibility is first fabricated to clarify its potential application in wearable electronic devices.

An ethyl acetate-based electrolyte, which exhibits a high boiling point, a low freezing point, and a sufficient ionic conductivity at ultra-low temperature of À70 C, was developed. Taking advantage of such an electrolyte, Li-ion full cells based on organic electrodes can work well and show outstanding performance within a wide operation temperature range from À70 C to +55 C.

Low-cost alkaline water electrolysis has been considered a sustainable approach to producing hydrogen using renewable energy inputs, but preventing hydrogen/oxygen mixing and efficiently using the instable renewable energy are challenging. Here, using nickel hydroxide as a redox mediator, we decouple the hydrogen and oxygen production in alkaline water electrolysis, which overcomes the gas-mixing issue and may increase the use of renewable energy. In this architecture, the hydrogen production occurs at the cathode by water reduction, and the anodic Ni(OH)2 is simultaneously oxidized into NiOOH. The subsequent oxygen production involves a cathodic NiOOH reduction (NiOOH→Ni(OH)2) and an anodic OH− oxidization. Alternatively, the NiOOH formed during hydrogen production can be coupled with a zinc anode to form a NiOOH-Zn battery, and its discharge product (that is, Ni(OH)2) can be used to produce hydrogen again. This architecture brings a potential solution to facilitate renewables-to-hydrogen conversion.

The magnesium-metal battery, which consists of a cathode, a Mg-metal anode, and a nonaqueous electrolyte, is a safer and less expensive alternative to the popular Li-ion battery. However, the performance of Mg batteries is greatly limited by the low electrochemical oxidative stability of nonaqueous electrolytes, the slow Mg 2+ diffusion into the cathode, and the irreversibility of Mg striping and plating on the Mg metal anode. Here, we report the first Mg-ion battery using a Mg 2+ aqueous electrolyte, nickel hexacyanoferrate cathode, and polyimide anode. The operation depends on Mg 2+ intercalation−deintercalation at the cathode and reversible enolization at the anode, accompanied by Mg 2+ transport between cathode and anode. The cell exhibits a maximum cell voltage of 1.5 V and a supercapacitor-like high power, and it can be cycled 5000 times. This system points the way to improved Mg-based rechargeable batteries.

Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

Three-dimensional ordered mesoporous/macroporous carbon sphere arrays (MMCSAs) are synthesized and then used as a catalyst for Li-O2 batteries. The hierarchical porous structure of the MMCSAs not only facilitates electrolyte immersion and Li(+) diffusion but also provides an effective space for O2 diffusion and O2 /Li2 O2 conversion, and thus efficiently improves the performance of Li-O2 batteries.