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Rechargeable magnesium batteries are regarded as a promising multi-valent battery system for low-cost and sustainable energy storage applications. Boron-based organic magnesium salts with terminal substituent fluorinated anions (Mg[B(OR F ) 4 ] 2 , R F =fluorinated alkyl) have exhibited impressive electrochemical stability and oxidative stability. Nevertheless, their deployment is hindered by the complicated synthesis routes and the surface passivation of Mg metal anode. Herein, we report the design of an advanced electrolyte formulation comprised of tri(hexafluoroisopropyl) borate (B(HFIP) 3 ) and iodine (I 2 ) in 1,2-dimethoxyethane (DME) solvent, which eventually convert into a Mg[B(HFIP) 4 ] 2 /DME-MgI 2 electrolyte system upon interacting with Mg anode. The Mg anode reacts with I 2 and the electron-accepting B(HFIP) 3 , leading to the in situ formation of a solid-electrolyte interphase layer composed of MgF 2 and MgI 2 species that can facilitate fast and stable Mg plating/stripping. Compared with the pristine Mg[B(HFIP) 4 ] 2 /DME electrolyte, the Mg[B(HFIP) 4 ] 2 /DME-MgI 2 electrolyte exhibited superior electrochemical performance including an ultra-low overpotential (~80 mV), high Coulombic efficiency and a long-cycling period over 1500 h. In result, the rechargeable magnesium batteries with Mg[B(HFIP) 4 ] 2 /DME-MgI 2 electrolyte and Chevrel-phase Mo 6 S 8 cathode show outstanding compatibility, rapid kinetics, and stable cyclability for over 1200 cycles, surpassing all previously reported boron-based electrolytes. This work introduces a promising halogen-enhancement strategy for boron-based Mg-ion electrolytes, with the overarching goal of establishing favorable solid-electrolyte interphases that are pivotal for the advancement and optimization of multi-valent secondary batteries., (© 2024 Wiley-VCH GmbH.)

Aqueous zinc-ion batteries (AZIBs) are considered as the promising candidates for large-scale energy storage because of their high safety, low cost and environmental benignity. The large-scale applications of AZIBs will inevitably result in a large amount of spent AZIBs, which not only induce the waste of resources, but also pose environmental risks. Therefore, sustainable AZIBs have to be considered to minimize the risk of environmental pollution and maximize the utilization of spent compounds. Herein, this minireview focuses on the sustainability of AZIBs from material design and recycling techniques. The structure and degradation mechanism of AZIBs are discussed to guide the recycling design of the materials. Subsequently, the sustainability of component materials in AZIBs is further analysed to pre-evaluate their recycling behaviors and mentor the selection of more sustainable component materials, including active materials in cathodes, Zn anodes, and aqueous electrolytes, respectively. According to the features of component materials, corresponding green and economic approaches are further proposed to realize the recycling of active materials in cathodes, Zn anodes and electrolytes, respectively. These advanced technologies endow the recycling of component materials with high efficiency and a closed-loop control, ensuring that AZIBs will be the promising candidates of sustainable energy storage devices. This review will offer insight into potential future directions in the design of sustainable AZIBs., (© 2024 Wiley-VCH GmbH.)

Aqueous Zn-I batteries hold great potential for high-safety and sustainable energy storage. However, the iodide shuttling effect and the hydrogen evolution reaction that occur in the aqueous electrolyte remain the main obstacles for their further development. Herein, the design of a cathode/electrolyte mutualistic aqueous (CEMA) Zn-I battery based on the inherent oxidation ability of aqueous trifluoromethanesulfonate ((OTf) - ) electrolyte toward triiodide species is presented. This results in the formation of iodine sediment particles assembled by fine iodine nanocrystals (≈10 nm). An iodine host cathode with high areal iodine loading is realized via a spontaneous absorption process that enriched redox-active iodine and iodide species from aqueous electrolyte onto nanoporous carbon based current collector. By tuning iodide redox process and suppressing competitive hydrogen evolution reaction, the assembled CEMA Zn-I batteries demonstrate a remarkable capacity retention of 76.9% over 1000 cycles at 0.5 mA cm -2 . Moreover, they exhibit a notable rate capability, with a capacity retention of 74.6% when the current density is increased from 0.5 to 5.0 mA cm -2 . This study demonstrates the feasibility of using the oxidation effect to repel redox-active species from the electrolyte to the cathode, paving a new avenue for high-performance aqueous Zn-I batteries., (© 2023 Wiley-VCH GmbH.)

Metallic zinc (Zn) is a highly promising anode material for aqueous energy storage systems due to its low redox potential, high theoretical capacity, and low cost. However, rampant dendrites/by-products and torpid Zn 2+ transfer kinetics at electrode/electrolyte interface severely threaten the cycling stability, which deteriorate the electrochemical performance of Zn-ion batteries. Herein, an interfacial engineering strategy to construct alkaline earth fluoride modified metal Zn electrodes with long lifespan and high capacity retention is reported. The compact fluoride layer is revealed to guide uniform Zn stripping/plating and accelerate the transfer/diffusion of Zn 2+ via Maxwell-Wagner polarization. A series of in situ and ex situ spectroscopic studies verified that the fluoride layer can guide uniform Zn stripping/plating. Electrochemical kinetics analyses reveal that positive effect on the removal of Zn 2+ solvation sheath provided by fluoride layer. Meanwhile, this fluoride coating layer can act as a barrier between the Zn electrode and electrolyte, providing a high electrode overpotential toward hydrogen evolution reaction to hold back H 2 evolution. Consequently, the fluoride-modified Zn anode exhibited a capacity retention of 88.2% after 4000 cycles under10 A g -1 . This work opens up a new path to interface engineering for propelling the exploration of advanced rechargeable aqueous Zn-ion batteries., (© 2023 Wiley-VCH GmbH.)

Air self-charging aqueous metal-ion batteries usually suffer from capacity loss after self-charging cycles due to the formation of basic salts on cathodes in the near-neutral electrolytes. Here, air self-charging Pb/pyrene-4,5,9,10-tetraone (PTO) batteries based on proton chemistry are developed in acidic electrolyte. The fast kinetics of H + uptake/removal endows the battery with enhanced electrochemical performance. Owing to the high standard electrode potential of oxygen in acid electrolyte, the discharged cathodes are spontaneously oxidized by oxygen in air along with H + extraction and thus achieve self-charging without external power supply. Notably, the air self-charging mechanism involved H + -based redox can effectively avoid the generation of basic salts on self-charging electrodes and thus guarantee long-term self-charging/galvanostatic discharging cycles of Pb/PTO batteries. This work provides a promising strategy for designing long-cycle air self-charging systems., (© 2022 Wiley-VCH GmbH.)

Aqueous manganese-ion batteries (MIBs) are promising energy storage systems because of the distinctive merits of Mn metal, in terms of high abundance, low cost, nontoxicity, high theoretical capacity and low redox potential. Conventional MIBs are based on the Mn 2+ ion storage mechanism, whereas the capacity in cathode materials is generally limited due to the high charge density and large solvated ionic radius of Mn 2+ ions in aqueous electrolytes. Herein, proton intercalation chemistry is introduced in aqueous MIBs, in which the layered Al 0.1 V 2 O 5 ⋅1.5 H 2 O (AlVO) cathode exhibits a consequent Mn 2+ and H + ion intercalation/extraction process. Such an energy storage mechanism contributes to enhanced electrochemical performance, including high capacity, fast reaction kinetics and stable cycling behavior. Benefiting from this proton intercalation chemistry, the aqueous Mn||AlVO cells could deliver high specific energy and power simultaneously. This work provides a route for the design of high-performance aqueous MIBs., (© 2022 Wiley-VCH GmbH.)

Manganese oxides are promising cathode materials for aqueous zinc-ion batteries (ZIBs) due to their high energy density and low cost. However, in their discharging processes, the Jahn-Teller effect and Mn 3+ disproportionation often lead to irreversible structural transformation and Mn 2+ dissolution, deteriorating the cycling stability of ZIBs. Herein, ZnMn 2 O 4 quantum dots (ZMO QDs) were introduced into a porous carbon framework by in-situ electrochemically inducing Mn-MIL-100-derived Mn 3 O 4 quantum dots and the carbon composite. In such ZMO QDs and carbon composite, the quantum dot structure endows ZnMn 2 O 4 with a shorter ion diffusion route and more active sites for Zn 2+ . The conductive carbon framework is beneficial to the fast transport of electrons. Furthermore, at the interface between the ZMO QDs and the carbon matrix, the Mn-O-C bonds are formed. They can effectively suppress the Jahn-Teller effect and manganese dissolution of discharge products. Therefore, Zn/ZMO QD@C batteries display remarkably enhanced electrochemical performance., (© 2022 Wiley-VCH GmbH.)

As emerging 2D materials, arsenene and arsenic materials have attracted rising interest in the past few years. The diverse crystalline phases, exotic electrical characteristics, and widespread applications of 2D arsenene and arsenic bring them great research value and utilization potential. Herein, the recent progress of 2D arsenene and arsenic is reviewed in terms of fundamental properties, preparation, and applications. The fundamental properties of 2D arsenene and arsenic, including the crystal phases, environmental stability, and electrical structure, from theoretical to experimental reports are first summarized. Then, the experimental processes for preparing 2D arsenene and arsenic, along with their respective advantages and disadvantages, are introduced including epitaxial growth, mechanical exfoliation, and liquid-phase exfoliation. Moreover, applications of 2D arsenene and arsenic are discussed, suggesting a wide range of applications of 2D arsenene and arsenic in field-effect transistors, sensors, catalysts, biological applications, and so on. Finally, some perspectives about the challenges and opportunities of promising 2D arsenene and arsenic are provided. This review provides a helpful guidance and stimulates more focus on future explorations and developments of 2D arsenene and arsenic., (© 2021 Wiley-VCH GmbH.)

All-organic proton batteries are attracting extensive attention due to their sustainability merits and excellent rate capability. Generally, strong acids (e.g. H 2 SO 4 ) have to be employed as the electrolytes to provide H + for all-organic proton batteries due to the high H + intercalation energy barrier. Until now, the design of all-organic proton batteries in mild electrolytes is still a challenge. Herein, a poly(2,9-dihydroquinoxalino[2,3-b]phenazine) (PO) molecule was designed and synthesized, where the adjacent C=N groups show two different chemical environments, resulting in two-step redox reactions. Moreover, the two reactions possess considerable voltage difference because of the large LUMO energy gap between PO and its reduction product. More impressively, the C=N groups endow the π-conjugated PO molecule with H + uptake/removal in the ZnSO 4 electrolyte. As a result, a symmetric all-organic proton battery is achieved in a mild electrolyte for the first time, which exhibits enhanced electrochemical performance and also broadens the chemistry of proton-based batteries., (© 2021 Wiley-VCH GmbH.)

Rechargeable silicon anode lithium ion batteries (SLIBs) have attracted tremendous attention because of their merits, including a high theoretical capacity, low working potential, and abundant natural sources. The past decade has witnessed significant developments in terms of extending the lifespan and maintaining high capacities of SLIBs. However, the detrimental issue of low initial Coulombic efficiency (ICE) toward SLIBs is causing more and more attention in recent years because ICE value is a core index in full battery design that profoundly determines the utilization of active materials and the weight of an assembled battery. Herein, a comprehensive review is presented of recent advances in solutions for improving ICE of SLIBs. From design perspectives, the strategies for boosting ICE of silicon anodes are systematically categorized into several aspects covering structure regulation, prelithiation, interfacial design, binder design, and electrolyte additives. The merits and challenges of various approaches are highlighted and discussed in detail, which provides valuable insights into the rational design and development of state-of-the-art techniques to deal with the deteriorative issue of low ICE of SLIBs. Furthermore, conclusions and future promising research prospects for lifting ICE of SLIBs are proposed at the end of the review., (© 2021 Wiley-VCH GmbH.)

The electrochemical performance of layered vanadium oxides is often improved by introducing guest species into their interlayer. Guest species with high stability in the interlayer and weak interaction with Zn 2+ during charge/discharge process are desired to promoting reversible Zn 2+ transfer. Herein, a universal compensation strategy was developed to introduce various polar organic molecules into the interlayer of Al x V 2 O 5 ·nH 2 O by replacing partial crystal water. The high-polar groups in the organic molecules have a strong electrostatic attraction with pre-intercalated Al 3+ , which ensures that organic molecules can be anchored in the interlayer of hydrated vanadates. Simultaneously, the low-polar groups endow organic molecules with a weak interaction with Zn 2+ during cycling, thus liberalizing reversible Zn 2+ transfer. As a result, Al x V 2 O 5 with polar organic molecules displays enhanced electrochemical performance. Furthermore, based on above cathode material, a pouch cell was assembled by further integrating a dendrite-free N-doped carbon nanofiber@Zn anode, displaying an energy density of 50 Wh kg -1 . This work provides a path for designing stable guest species with a weak interaction with Zn 2+ in the interlayer of layered vanadium oxide towards high-performance cathode materials of aqueous Zn batteries., (© 2021 Wiley-VCH GmbH.)

Conventional aqueous batteries usually suffer from serious capacity loss under subzero conditions owing to the freeze of electrolytes. To realize the utilization of aqueous batteries in extremely cold climates, low-temperature aqueous battery systems have to be developed. Herein, an aqueous Pb-quinone battery based on p-chloranil/reduced graphene oxide (PCHL-rGO) in H 2 SO 4 electrolyte is developed. Such aqueous Pb/PCHL-rGO batteries display H + insertion chemistry, which endows the batteries with fast reaction kinetics and high rate capability. In addition, the hydrogen bonds between water molecules can be significantly damaged in electrolyte by modulating the interaction between SO 4 2- and water molecules, lowering the freezing point of electrolyte. As a result, the Pb/PCHL-rGO batteries deliver extraordinary electrochemical performance even at -70 °C. This work will broaden the horizons of aqueous batteries and open up new opportunities to construct low-temperature aqueous batteries., (© 2021 Wiley-VCH GmbH.)

The electrochemical performance of vanadium-oxide-based cathodes in aqueous zinc-ion batteries (ZIBs) depends on their degree of crystallinity and composite state with carbon materials. An in situ electrochemical induction strategy was developed to fabricate a metal-organic-framework-derived composite of amorphous V 2 O 5 and carbon materials (a-V 2 O 5 @C) for the first time, where V 2 O 5 is in an amorphous state and uniformly distributed in the carbon framework. The amorphous structure endows V 2 O 5 with more isotropic Zn 2+ diffusion routes and active sites, resulting in fast Zn 2+ transport and high specific capacity. The porous carbon framework provides a continuous electron transport pathway and ion diffusion channels. As a result, the a-V 2 O 5 @C composites display extraordinary electrochemical performance. This work will pave the way toward design of ZIB cathodes with superior rate performance., (© 2020 Wiley-VCH GmbH.)

Organic electroactive compounds are attractive to serve as the cathode materials of aqueous zinc-ion batteries (ZIBs) because of their resource renewability, environmentally friendliness and structural diversity. Up to now, various organic electrode materials have been developed and different redox mechanisms are observed in aqueous Zn/organic battery systems. In this Minireview, we present the recent developments in the energy storage mechanisms and design of the organic electrode materials of aqueous ZIBs, including carbonyl compounds, imine compounds, conductive polymers, nitronyl nitroxides, organosulfur polymers and triphenylamine derivatives. Furthermore, we highlight the design strategies to improve their electrochemical performance in the aspects of specific capacity, output voltage, cycle life and rate capability. Finally, we discuss the challenges and future perspectives of aqueous Zn/organic batteries., (© 2020 Wiley-VCH GmbH.)

Proton storage in rechargeable aqueous zinc-ion batteries (ZIBs) is attracting extensive attention owing to the fast kinetics of H + insertion/extraction. However, it has not been achieved in organic materials-based ZIBs with a mild electrolyte. Now, aqueous ZIBs based on diquinoxalino [2,3-a:2',3'-c] phenazine (HATN) in a mild electrolyte are developed. Electrochemical and structural analysis confirm for the first time that such Zn-HATN batteries experience a H + uptake/removal behavior with highly reversible structural evolution of HATN. The H + uptake/removal endows the Zn-HATN batteries with enhanced electrochemical performance. Proton insertion chemistry will broaden the horizons of aqueous Zn-organic batteries and open up new opportunities to construct high-performance ZIBs., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Rechargeable magnesium batteries have attracted increasing attention due to the high theoretical volumetric capacities, dendrite formation-free characteristic and low cost of Mg metal anodes. However, the development of magnesium batteries is seriously hindered by the lack of capable cathode materials with long cycling life and fast solid-state diffusion kinetics for highly-polarized divalent Mg 2+ ions. Herein, vanadium tetrasulfide (VS 4 ) with special one-dimensional atomic-chain structure is reported to be able to serve as a favorable cathode material for high-performance magnesium batteries. Through a surfactant-assisted solution-phase process, sea-urchin-like VS 4 nanodendrites are controllably prepared. Benefiting from the chain-like crystalline structure of VS 4 , the S 2 2- dimers in the VS 4 nanodendrites provide abundant sites for Mg 2+ insertion. Moreover, the VS 4 atomic-chains bonded by weak van der Waals forces are beneficial to the diffusion kinetics of Mg 2+ ions inside the open channels of VS 4 . Through a series of systematic ex situ characterizations and density functional theory calculations, the magnesiation/demagnesiation mechanism of VS 4 are elucidated. The VS 4 nanodendrites present remarkable performance for Mg 2+ storage among existing cathode materials, exhibiting a remarkable initial discharge capacity of 251 mAh g -1 at 100 mA g -1 and an impressive long-term cyclability at large current density of 500 mA g -1 (74 mAh g -1 after 800 cycles)., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)