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Manganese oxide is among the most promising cathode materials for rechargeable aqueous zinc‐ion batteries due to its abundant reserves, low toxicity, and high theoretical capacity. However, the occurrence of Mn dissolution and structural collapse during the charge and discharge process, as well as the hydrogen evolution reaction, zinc dendrite formation, and corrosion on the anode surface, have seriously hindered practical applications. Here, a novel cathode material design is proposed intended to enhance both cathode and anode stability simultaneously. Specifically, an inherently stable CuMn2O4 is employed as cathode material, which demonstrates good maintenance of its spinel structure during cycling. Interestingly, insertion of Zn2+‐ions leads to the extraction of Cu2+‐ions from CuMn2O4, subsequently in situ reduces to Cu0, which results in extra capacity and improves electrical conductivity. The migration of Cu2+ ions into the Zn anode surface during the charge process eventuated the formation of copper–zinc alloys via electrodeposition. Moreover, the reconstructed anode exhibits superior stability and corrosion resistance during the Zn plating‐stripping process. Consequently, the CuMn2O4 electrode demonstrates a markedly improved cycle capability compared to the spinel Mn3O4 electrode. This study highlights an unconventional copper electrochemistry in aqueous Zn‐Mn batteries and introduces a new design principle for high‐performance aqueous zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

Calcium metal batteries, as one of the promising alternatives beyond Li‐metal technology, is held back by the lack of suitable cathodes of considerable energy storage capability, and Ca anodes of long‐term stability and lower polarization potentials for Ca‐plating/stripping. Here, by recycling cellulose waste paper, feasible cathodes for Ca‐metal batteries of good high‐voltage and wide‐window‐voltage adaptability (0.005–4.9 V versus Ca/Ca2+), and impressive energy density (≈517.5 Wh kg−1 at 0.1 A g−1) are developed. Meanwhile, through tailorable Ca‐plating/stripping potentials (∆V≈ 0.65 V) realized by a modified electrolyte of Li+, Ca2+, BF4−, and PF6− multi‐ions system, the proof‐of‐concept Ca‐metal batteries not only delivered enhanced storage capability (101 mAh g−1 versus 51 mAh g−1 at 0.1 A g−1 in the window voltage of 2.0–4.7 V) and cycling stability (≈77% capacity retention for 100 cycles), but also simultaneously show a high output average working voltage of ≈3.2 V. The work provides a hint that mixed metal deposition under multi‐ions electrolyte system may address the challenging issues faced by single alkali or alkaline‐earth metal batteries. [ABSTRACT FROM AUTHOR]

Recently, metal organic framework (MOF) nanostructures have been frequently reported in the field of energy storage, specifically for Li-ion or Na-ion storage. By inter-separating the active sites of metal cluster and organic ligands, MOF nanostructures are exceptionally promising for realizing fast ion exchange and high-efficiency transportation and addressing the intricate issues that the energy-intensive Li-ion batteries have faced over many years. The related ion-storage mechanism remains to be explored. Is the traditional redox reaction mechanism operative for these nanostructure, as it is for transitional metal oxide? Herein, taking [Fe 3 O(BDC) 3 (H 2 O) 2 (NO 3 )]n (Fe-MIL-88B) as an example, an Fe-based metal organic polyhedral nanorods of MIL–88 B structure was designed as an anode for Li-ion storage. When tested at 60 mA g −1 , the nanoporous Fe-MIL–88 B polyhedral nanorods retained a reversible capacity of 744.5 mAh g −1 for more than 400 cycles. Ex situ characterizations of the post-cycled electrodes revealed that both the transition metal ions and the organic ligands contributed to the high reversible specific capacity. The polyhedral nanorods electrodes held the metal-organic skeleton together throughout the battery operation, although in a somewhat different manner than the pristine ones. This further substantiated that some MOF nanostructures are more appropriate than others for stable lithiation/delithiation processes. State-of-the-art CR2032 full cells showed that a high capacity of 86.8 mAh g −1 that was retained after 100 cycles (herein, the capacity for the full cell was calculated based on both the weight of the anode and the cathode, and the charge-discharge rate was 0.25C), when commercial LiFePO 4 powders were used as the cathode. [ABSTRACT FROM AUTHOR]

Supercapacitors or electrochemical capacitors, as energy storage devices, require very stable positive electrode materials for useful applications. Although most positive electrodes are based on crystalline mixed-metal hydroxides, their pseudocapacitors usually perform poorly or have a short cycle life. High activities can be achieved with amorphous phases. Methods to produce amorphous materials are also not typically amenable towards mixed-metal compositions. It is demonstrated that electrochemistry in an ambient environment can be used to produce a series of amorphous mixed-metal hydroxides with a homogeneous distribution of metals for use as positive electrode materials in a supercapacitor. The integrated performance of the amorphous ternary mixed-metal hydroxide pseudocapacitor is superior to that of crystalline materials. The amorphous Ni-Co-Fe hydroxide supercapacitor is characterized by a long-term cycling stability that retained 94% of its capacity after 20 000 cycles. This is much higher than the cycle life of crystalline devices. These results show the broad applicability of this methodology towards new electrode materials for high-performance supercapacitors, especially amorphous mixed-metal hydroxides, as advanced electrode materials. [ABSTRACT FROM AUTHOR]

Porous NiCo 2 S 4 nanosheets derived from bimetallic MOFs directly grow on a conductive substrate as a binder-free electrode. The unique open-structure NiCo 2 S 4 with porosity facilitates the diffusion of electrolyte and possess abundant electroactive sites, which presents a high specific capacity and long-term cycling stability. An assembled hybrid capacitor exhibits the practical performance of high energy density and excellent cycling property. • The porous NiCo 2 S 4 nanosheet arrays derived from bimetallic Metal-organic frameworks derivatives are prepared. • The effect of NiCo 2 S 4 morphology on electrochemical performance and reaction mechanism are discussed. • A hybrid supercapacitor device exhibits high energy density and superior cycling stability. Recently, metal-organic frameworks (MOFs) derived materials in the form of bulk powders with attractive chemical and structural properties show broad application in electrochemical energy storage. Bimetallic materials-based MOFs usually show better electrochemical properties than that of monometallic derivatives, while achieving the bimetallic MOFs-derived materials on current collector as a binder-free electrode is still a challenge. Here we report a new approach to directly obtain a binder-free electrode of bimetallic MOFs-derived NiCo 2 S 4 nanosheet arrays on nickel foam (NF) substrate. The porous NiCo 2 S 4 nanosheet arrays providing fast electrolyte permeation and rich electrochemical active sites, show an excellent specific capacity of 1354.4 C g−1, high rate performance, and outstanding cycling stability of 82.6% retention after 10,000 cycles. A hybrid supercapacitor assembled with the as-obtained binder-free electrode as a cathode and active carbon as an anode, exhibits high energy density of 49.1 Wh kg−1 at a power density of 375 W kg−1 and superior cycling stability of 94.5% retention after 10,000 cycles. These results offer a novel and general approach to construct binder-free electrode materials with advanced performance for the portable and practical energy storage device. [ABSTRACT FROM AUTHOR]

Morphology reshaping or reconfiguration, a concept widely used in plastic surgery, energy harvesting, and reconfigurable robots, is introduced for the first time to construct densified electrodes and realize compact Li‐ion storage desirable for high specific energy storage field. Hausmannite‐based hybrid materials, as a proof‐of‐concept prototype, engineered by 1‐methyl‐2‐pyrrolidinone‐soluble surface/interface organic encapsulation, which is crucial in reshaping, exhibit a remarkable increase in the volumetric capacity of more than five times after this process (≈1889 Ah L−1 vs ≈322 Ah L−1). With the simultaneous maintenance of the intrinsic nature, good contact, and no collapsed/agglomerated unit structures of the materials in electrodes, the design affords a maximal increase in the packing compactness and manifests no sacrifice of the reversible ion storage capability (1150 mAh g−1 at 40 mA g−1), stable cycling (≈100% capacity retention), high rate performance (185 mAh g−1 at 10 A g−1), and long lifespan (1000 cycles with 108% capacity retention, ≈455 mAh g−1 at 3 A g−1) for relatively highly loaded electrodes (active materials: 1.20–5.34 mg cm−2). The concept may not only shed new light on fabricating advanced Si‐based and other high capacity–related densified Li storage electrodes but also inject fresh vitality into the field of high‐density power sources. [ABSTRACT FROM AUTHOR]

Abstract Rechargeable aqueous zinc-ion batteries (ZIBs) are very promising energy storage systems owing to their low cost, high reliability, and high volumetric energy density; however, the stiff challenge for the progress of ZIBs is the lack of suitable materials that permit divalent ion-intercalation/deintercalation with fast kinetics, long cycling durations, and high rate capabilities. Herein, we demonstrate V 10 O 24 ·12H 2 O dendrites with a large interlayer spacing of 1.4 nm, fabricated through a simple hydrothermal method. The unique, open, and stable structure complemented by a mixed valence enables a satisfactory battery performance: a specific capacity of 164.5 mAh g−1, long-term cycling stability of 80.1% capacity retention after 3000 cycles, and high power density of 12247.8 W kg−1 at a high energy density of 88.5 Wh kg−1. This study provides a viable and attractive cathode material for practical ZIBs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Boron-containing metal-free catalysts (BC 4 N and BC 6 N 2) as efficient cathode materials of lithium-sulfur batteries. • BC 4 N and BC 6 N 2 possess stronger trapping capability for LiPs/S 8 than previously reported metal-free catalysts and perform even better than some metal-containing catalysts. • BC 4 N exhibits superior catalytic performance for Li 2 S decomposition with low energy barrier (0.8 eV) • Crystalline phase BC 4 N and BC 6 N 2 containing high density and homogeneous distribution of active boron sites could overcome the challenges faced by other carbon-based metal-free catalysts obtained via doping strategy. Lithium-sulfur (Li-S) batteries are considered as ideal next-generation energy storage devices, the commercial applications of them are hindered by their inherent drawbacks of shuttle effect and sluggish conversion among lithium polysulfides (LiPs). To tackle these issues, significant research efforts have been devoted to designing high-performance metal-based catalysts implemented in the sulfur cathodes, which however face the challenges of source scarcity and cycling instability. Here, based on first-principles calculations, we investigated our previously predicted two-dimensional (2D) metal-free boron-containing catalysts of BC 4 N and BC 6 N 2 and found that they possess strong trapping capability for LiPs adsorption energy as low as −6.41 eV beneficial for suppressing shuttle effect. Moreover, BC 4 N exhibits even superior catalytic performances toward the redox of sulfur, which can be evidenced by the low free energy change of the rate determining step of reduction reaction and small energy barrier of 0.80 eV for Li 2 S decomposition, outperforming most previously reported metal-based catalysts. Our research can pave a new way for designing new 2D metal-free catalysts in Li-S batteries, which highlights the importance of boron atoms in suppressing shuttle effect and catalyzing sulfur redox. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries (AZIBs), which are low‐cost and environmentally friendly, have been regarded feasible for large‐scale energy storage. But the widespread application of AZIBs is hindered by lack of suitable cathode materials with high capacity and long cycle life. The zinc‐storage mechanisms, especially the formation of basic zinc salt (BZS), are still unclear. Here, Ag2V4O11 is developed as a cathode material for AZIBs, which delivers a specific capacity of 213 mA h g−1 and excellent cycling performance (93% capacity retention after 6000 cycles). The reversible formation/decomposition of BZS and reduction/oxidation of metallic Ag are ascertained during the insertion/extraction of Zn(H2O)62+. Remarkably, the phase composition of BZS in Zn(CF3SO3)2‐based electrolyte is identified first. The role of in situ formed Ag nanoparticles is simulated by employing the commercial Ag nanoparticles as an additive into the V2O5‐based electrodes. The introduction of Ag significantly improves the specific capacity (at least 50% improvement) and accordingly it is proposed that the pseudo‐Zn–air reaction (oxygen reduction reaction‐like redox reaction happens on material surface in a closed system) promotes the electrochemical performance of Ag2V4O11. This work reveals the BZS rather than unknown new phases on the electrode surface and puts forward a possible way in raising electrochemical properties by utilizing the pseudo‐Zn–air reaction. [ABSTRACT FROM AUTHOR]

Aqueous zinc batteries are considered as promising alternatives to lithium ion batteries owing to their low cost and high safety. However, the developments of state‐of‐the‐art zinc‐ion batteries (ZIB) and zinc–air batteries (ZAB) are limited by the unsatisfied capacities and poor cycling stabilities, respectively. It is of significance in utilizing the long‐cycle life of ZIB and high capacity of ZAB to exploit advanced energy storage systems. Herein, a bulk composite of graphene oxide and vanadium oxide (V5O12·6H2O) as cathode material for aqueous Zn batteries in a mild electrolyte is employed. The battery performance is demonstrated to arise from a combination of the reversible cations insertion/extraction in vanadium oxide and especially the electrochemical redox reactions on the surface functional groups of graphene oxide (named as pseudo‐Zn–air mechanism). Along with adjusting the hydroxyl content on the surface of graphene oxide, the specific capacity is significantly increased from 342 mAh g−1 to a maximum of 496 mAh g−1 at 100 mA g−1. The surface‐controlled kinetics occurring in the bulk composite ensure a high areal capacity of 10.6 mAh cm−2 at a mass loading of 26.5 mg cm−2, and a capacity retention of 84.7% over 10 000 cycles at a high current density of 10 A g−1. [ABSTRACT FROM AUTHOR]