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Magnesium‐ion batteries (MIBs) have promising applications because of their high theoretical capacity and the natural abundance of magnesium Mg. However, the kinetic performance and cyclic stability of cathode materials are limited by the strong interactions between Mg ions and the crystal lattice. Here, we demonstrate the unique Mg2+‐ion storage mechanism of a hierarchical accordion‐like vanadium oxide/carbon heterointerface (V2O3@C), where the V2O3 crystalline structure is reconstructed into a MgV3O7∙H2O phase through an anodic hydration reaction upon first cycle, for the improved kinetic and cyclic performances. As verified by in situ/ex situ spectroscopic and electrochemical analyses, the fast charge transfer kinetics of the V2O3@C cathode were due to the crystal‐reconstruction and chemically coupled heterointerface. The V2O3@C demonstrated an ultrahigh rate capacity of 130.4 mAh g−1 at 50 000 mA g−1 and 1000 cycles, achieving a Coulombic efficiency of 99.6%. The high capacity of 381.0 mA h g−1 can be attributed to the reversible Mg2+‐ion intercalation mechanism observed in the MgV3O7∙H2O phase using a 0.3 M Mg(TFSI)2/ACN(H2O) electrolyte. Additionally, within the voltage range of 2.25 V versus Mg/Mg2+, the V2O3@C exhibited a capacity of 245.1 mAh g−1 when evaluated with magnesium metal in a 0.3 M Mg(TFSI)2 + 0.25 M MgCl2/DME electrolyte. These research findings have important implications for understanding the relationship between the Mg‐ion storage mechanism and reconstructed crystal phase of vanadium oxides as well as the heterointerface reconstruction for the rational design of MIB cathode materials. [ABSTRACT FROM AUTHOR]

Hydrogel electrolytes consisting of salt ions, water solvents, and 3D polymer networks play the roles of an electrolyte and a separating membrane. These are receiving attention as a substitute for the currently used liquid electrolyte/separator materials in aqueous Zn metal batteries (AZMBs). In this study, a structural composite hydrogel electrolyte is designed by incorporating layered alumina microplatelets within a polymer matrix to achieve high mechanical strength, stiffness, hardness, thermal conductivity, and a large dielectric constant. The hydrogel electrolyte simultaneously achieves mechanical robustness and fast Zn ion transfer, enabling uniform Zn deposition without notable dendrite growth and propagation. Moreover, the rapid heat‐dissipating ability of the electrolyte demonstrates the potential for effective thermal management of AZMB cells. Consequently, Zn||Zn symmetric cells composed of the as‐designed electrolyte exhibit stable Zn plating/stripping behavior at various temperatures. Zn||poly(3,4‐ ethylenedioxythiophene)‐vanadium pentoxide (PVO) full cells have large energy densities of 356.9 W h kg−1 at 25 °C and 216.6 W h kg−1 at −20 °C and long‐term stability over 1,000 cycles. Further, pouch‐type Zn||PVO full cells with large energy densities operate stably while bent, folded, rolled, cut in half, or immersed in boiling and freezing water. [ABSTRACT FROM AUTHOR]

The deep understanding about the electrochemical behavior of the nanostructured electrode in electrolytes provides crucial insights for the rational design of electrode for sodium (Na)‐ion storage system (NIS). Here, we report redox charge transfer kinetics and reversibility of VO2(B) nanorod electrodes in both aqueous and organic electrolytes for NIS. The as‐synthesized VO2(B) nanorods show the reversible redox reaction with the higher specific and rate capacitances at high current density in aqueous electrolytes than in organic electrolytes. Temperature‐dependent impedance measurements demonstrate the more facile interfacial charge transfer of Na ions into VO2(B) nanorods in aqueous electrolytes. The reversible evolution in oxidation state and chemical composition of VO2(B) nanorods is observed in aqueous electrolytes, as confirmed by ex situ XRD and ex situ X‐ray photoelectron spectroscopy analyses. Given by the facile and reversible pseudocapacitive feature, the electrochemical performances of VO2(B) nanorods are further improved by constructing the hierarchical structure of the reduced graphene oxide‐VO2 composite for aqueous Na+ ion storage. [ABSTRACT FROM AUTHOR]

Owing to the earth‐abundant resources, cost effective materials and stable electrochemical properties, sodium‐ions batteries (SIBs) show long‐term potential in responding to the rapid consumption of lithium resources and the ever‐increasing development of new energy storage devices. Nevertheless, the intrinsic properties of the large ion radius (Na+ 1.02 Å vs Li+ 0.76 Å) and positive reduction potential (Na/Na+ −2.71 V vs Li/Li+ −3.04 V) may impede ion diffusion, thus causing serious volume expansion, resulting in poor cycling stability. To address these issues, the incorporation of active sites into carbonaceous anode is considered as an efficient strategy to enhance interfacial compatibility, enlarge interlayer distance, and supply reversible Faradic pseudo‐capacitance. Herein, the multiple active sites carbonaceous anodes for SIBs anode are comprehensively reviewed. Typically, carbonaceous materials are categorized into diffusion and surface controlled based on Na storage mechanism, and the concepts of intrinsic/extrinsic active sites are proposed according to the types of active sites. Furthermore, to reveal the reaction kinetics and guide the rational design of high performance anodes, the (spectro) electrochemical analysis methods and corresponding key parameters are introduced. Additionally, primary superiorities, essential issues, and supposed solutions of multiple active sites carbonaceous Na anodes are discussed and the future development directions are also proposed. This review may provide new design thoughts for high performance carbonaceous Na storage anodes. [ABSTRACT FROM AUTHOR]

Carbon is a simple, stable and popular element with many allotropes. The carbon family members include carbon dots, carbon nanotubes, carbon fibers, graphene, graphite, graphdiyne and hard carbon, etc. They can be divided into different dimensions, and their structures can be open and porous. Moreover, it is very interesting to dope them with other elements (metal or non‐metal) or hybridize them with other materials to form composites. The elemental and structural characteristics offer us to explore their applications in energy, environment, bioscience, medicine, electronics and others. Among them, energy storage and conversion are extremely attractive, as advances in this area may improve our life quality and environment. Some energy devices will be included herein, such as lithium‐ion batteries, lithium sulfur batteries, sodium‐ion batteries, potassium‐ion batteries, dual ion batteries, electrochemical capacitors, and others. Additionally, carbon‐based electrocatalysts are also studied in hydrogen evolution reaction and carbon dioxide reduction reaction. However, there are still many challenges in the design and preparation of electrode and electrocatalytic materials. The research related to carbon materials for energy storage and conversion is extremely active, and this has motivated us to contribute with a roadmap on 'Carbon Materials in Energy Storage and Conversion'. [ABSTRACT FROM AUTHOR]

Potassium- and sodium-ion batteries (PIBs and SIBs) have great potential as the next-generation energy application owing to the natural abundance of K and Na. Antimony (Sb) is a suitable alloying-type anode for PIBs and SIBs due to its high theoretical capacity and proper operation voltage; yet, the severe volume variation remains a challenge. Herein, a preparation of N-doped carbon-wrapped Sb nanoparticles (L-Sb/NC) using pulsed laser ablation and polydopamine coating techniques, is reported. As the anode for PIB and SIB, the L-Sb/NC delivers superior rate capabilities and excellent cycle stabilities (442.2 and 390.5 mA h g -1 after 250 cycles with the capacity decay of 0.037% and 0.038% per cycle) at the current densities of 0.5 and 1.0 A g -1 , respectively. Operando X-ray diffraction reveals the facilitated and stable potassiation and sodiation mechanisms of L-Sb/NC enabled by its optimal core-shell structure. Furthermore, the SIB full cell fabricated with L-Sb/NC and Na 3 V 2 (PO 4 ) 2 F 3 shows outstanding electrochemical performances, demonstrating its practical energy storage application., (© 2022 Wiley-VCH GmbH.)