Cycling Durability Research Articles

Electrodeposited CoMnS/NiCo2S4 nanocomposite for high performance supercapacitors

In this work, we report a facile two-step electrodeposition method to fabricate a CoMnS/NiCo2S4/NF (CMS/NCS/NF) composite on nickel foam (NF) for application of supercapacitor electrode. The electrochemical performance of this composite material has been extensively investigated, revealing superior performance compared to individual CMS/NF and NCS/NF materials. The CMS/NCS/NF composite exhibits an exceptionally high specific capacity of 707 C/g at a current density of 1 A/g in a three-electrode system. Remarkably, the material retains 92 % of its specific capacitance after 5000 cycles, indicating excellent cyclic stability and durability. To further explore its practical applications, we constructed a two-electrode symmetric supercapacitor using the CMS/NCS/NF electrode. This symmetric cell demonstrates an outstanding energy density of 97.5 Wh/kg and a peak power density of 12 kW/kg, underscoring its potential for high-performance energy storage applications. These comprehensive studies indicate that the synthesized CMS/NCS/NF is a highly promising candidate for supercapacitor electrodes, offering both high capacity and long-term stability. This work paves the way for the development of efficient and durable energy storage devices.

Artificially regulated interphase on natural graphite realizes rapid charge and durable high-temperature cycling of Li-ion batteries

Natural graphite (NG) is a strong competitor in the anode market of Li-ion batteries because of its low cost, rich resource, low energy consumption and low carbon dioxide emission during production. The main problems inhibiting its universal application are its high surface area and the attendant unstable solid/electrolyte interphase (SEI), leading to unsatisfactory cycling and rate performance. In this work, a Li+-conductive, thermally and mechanically stable organic polymer layer is successfully constructed on NG surface by virtue of the simultaneous polymerization and crosslinking reactions of chitosan (CS) and acrylic acid (AA). With controllable thickness, the polymer layer denoted as CSAA significantly decreases the specific surface area of NG, works as an inner SEI substrate greatly mitigating the decomposition of electrolyte, and induces the formation of a LiF-rich SEI outer layer. The SEI resistance and activation energy for charge-transfer reactions are considerably reduced. Benefiting from the superior properties of CSAA-derived SEI, the NG@CSAA anodes exhibit a high initial coulombic efficiency of 94.1 %, fast charge/discharge capability and prolonged cycle life at both 25 °C and 45 °C in the LiFePO4 cathodes-based full cells.

Clustered VCoCOx Nanosheets Anchored on MXene–Ti3C2@NF as a Superior Bifunctional Electrocatalyst for Alkaline Water Splitting

Ti3C2, one typical MXene, has great potential to be coupled with various transition metals. Herein, a novel and effective catalyst is developed by synergistically loading VCoCOx onto Ti3C2‐modified nickel foam (VCoCOx–Ti3C2@NF). Field emission scanning electron microscope and high‐resolution transmission electron microscopy are employed to characterize the morphology and structure. As expected, the catalyst optimized by response surface methodology attains overpotentials of 290 and 64 mV and Tafel slopes of 82 and 79 mV dec−1 for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), respectively. By using the bifunctional VCoCOx–Ti3C2@NF catalyst, the water splitting current density achieves 10 mA cm−2 in 1.0 mol L−1 KOH electrolyte at cell voltage of 1.52 V, comparable with the noble metal electrolyzer Pt@C@NF||RuO2@NF (1.57 V). Furthermore, the resulting catalyst exhibits excellent cycling durability after 120 h of continuous catalysis, which retains 103.8% and 105.4% of potential (V vs reversible hydrogen electrode) for OER and HER, respectively. Density functional theory calculation reveals that the Gibbs free energy barriers for the OER and HER intermediates are reduced due to the integration of VCoCOx with Ti3C2@NF. The fabricated VCoCOx–Ti3C2@NF catalyst is a promising electrochemical material for clean energy production.

Impact of concrete durability improvement on building life cycle carbon emissions: a case study of residential buildings in Northwest China.

Building carbon emissions (CE) have become the focus of the current topic, but there is still no mature typical building life cycle theory method from the perspective of building materials, and the research on the relationship between building durability and building life cycle is still insufficient. To this end, this study established a detailed calculation method for building carbon emissions (CE) and divided the building life cycle (BLC) into three stages: manufacturing, use, and demolition according to the result analysis. In addition, a durability improvement and carbon reduction scheme of "partition, resistance, and repair" is proposed, and the carbon emission reduction index of effectiveness index is proposed. The proposed method is applied to the case of residential buildings in Northwest China. The main conclusions are as follows: the CE of residential buildings are more dependent on the use stage. If the centralized heating system is adopted, the CE in the operation stage account for 80-90%. If the air conditioning refrigeration and heating system is adopted, the CE in the operation stage account for about 50%. Using the method of improving the durability of buildings to extend the service life of buildings is very significant for building carbon reduction (RC); the effectiveness index proposed in this paper includes key indicators such as total CE, service life, and building area. Compared with the traditional index, the effectiveness index is more accurate and comprehensive. CR is the focus of green building, but the impact of economy needs to be considered in practical engineering. In the future research, durability, CE, and economy need to be considered comprehensively for careful study.

Regulating Spin Polarization via Axial Nitrogen Traction at Fe−N5 Sites Enhanced Electrocatalytic CO2 Reduction for Zn−CO2 Batteries

AbstractSingle Fe sites have been explored as promising catalysts for the CO2 reduction reaction to value‐added CO. Herein, we introduce a novel molten salt synthesis strategy for developing axial nitrogen‐coordinated Fe‐N5 sites on ultrathin defect‐rich carbon nanosheets, aiming to modulate the reaction pathway precisely. This distinctive architecture weakens the spin polarization at the Fe sites, promoting a dynamic equilibrium of activated intermediates and facilitating the balance between *COOH formation and *CO desorption at the active Fe site. Notably, the synthesized FeN5, supported on defect‐rich in nitrogen‐doped carbon (FeN5@DNC), exhibits superior performance in CO2RR, achieving a Faraday efficiency of 99 % for CO production (−0.4 V vs. RHE) in an H‐cell, and maintaining a Faraday efficiency of 98 % at a current density of 270 mA cm−2 (−1.0 V vs. RHE) in the flow cell. Furthermore, the FeN5@DNC catalyst is assembled as a reversible Zn−CO2 battery with a cycle durability of 24 hours. In situ IR spectroscopy and density functional theory (DFT) calculations reveal that the axial N coordination traction induces a transformation in the crystal field and local symmetry, therefore weakening the spin polarization of the central Fe atom and lowering the energy barrier for *CO desorption.

Bismuth nanosheets guided zinc deposition enabled long-life aqueous zinc-based flow batteries

The poor cycling durability and low Coulombic efficiency (CE) of zinc (Zn) anodes substantially restrict their further development, which should be attributed to the severe uneven plating and hydrogen evolution reaction (HER) across the repeated plating/stripping processes. Herein, bismuth nanosheets decorated graphite felt (BiNS/GF) is constructed for Zn anode via galvanic replacement reaction. BiNS/GF affords more robust Zn nucleation sites, lower Zn nucleation overpotential and higher HER overpotential to guide even and dense Zn deposition. In addition, a total internal reflection imaging method is employed to detect micro-bubbles generated by HER on the electrode surface, revealing that BiNS prevents the formation of micro-bubbles and thus avoids dead Zn caused by unstable Zn deposition. As a proof of concept, BiNS/GF exhibits an average CE of 99.2 % in 300 cycles and a peak power density of 295.2 mW cm−2 at a current density of 380 mA cm−2 in aqueous neutral zinc-iron flow batteries. Therefore, it is reasonably anticipated that the BiNS/GF may emerge as suitable electrode for other aqueous zinc-based flow batteries.

Regulating Spin Polarization via Axial Nitrogen Traction at Fe-N5 Sites Enhanced Electrocatalytic CO2 Reduction for Zn-CO2 Batteries.

Single Fe sites have been explored as promising catalysts for the CO2 reduction reaction to value-added CO. Herein, we introduce a novel molten salt synthesis strategy for developing axial nitrogen-coordinated Fe-N5 sites on ultrathin defect-rich carbon nanosheets, aiming to modulate the reaction pathway precisely. This distinctive architecture weakens the spin polarization at the Fe sites, promoting a dynamic equilibrium of activated intermediates and facilitating the balance between *COOH formation and *CO desorption at the active Fe site. Notably, the synthesized FeN5, supported on defect-rich in nitrogen-doped carbon (FeN5@DNC), exhibits superior performance in CO2RR, achieving a Faraday efficiency of 99 % for CO production (-0.4 V vs. RHE) in an H-cell, and maintaining a Faraday efficiency of 98 % at a current density of 270 mA cm-2 (-1.0 V vs. RHE) in the flow cell. Furthermore, the FeN5@DNC catalyst is assembled as a reversible Zn-CO2 battery with a cycle durability of 24 hours. In situ IR spectroscopy and density functional theory (DFT) calculations reveal that the axial N coordination traction induces a transformation in the crystal field and local symmetry, therefore weakening the spin polarization of the central Fe atom and lowering the energy barrier for *CO desorption.

Dual‐Carbon Assisted Oxygen Vacancy Engineering for Optimizing Mn(III) Sites to Enhance Zn–air Battery Performances

AbstractOwing to kinetic‐sluggish nature of electrocatalytic oxygen transformation processes, it is pivotal to develop durable and efficient bifunctional air electrode catalysts for fabricating high‐performance Zn–air batteries (ZABs). In this work, oxygen vacancy (Ov) induced Mn(III) sites optimization is achieved via nano‐micro structure modulation. Protonated carbon nitride (p‐C3N4) is applied as a structure‐stiffening module to immobilize α‐MnO2 on N/P‐doped active carbon (NPAC) and induce Ov construction. X‐ray adsorption spectra (XAS) disclose the formation of Ov and Mn(III) sites in MCC, the unit coordination structure is well maintained with the aid of a dual‐carbon strategy. Mn(III) sites efficiently catalyze oxygen reduction/evolution reaction (ORR/OER), MCC shows high half‐wave potential (E1/2) of 0.88 V for ORR and low potential at 10 mA cm−2 (Ej = 10) of 1.64 V for OER. According to density functional theory (DFT) simulations analysis, the gorgeous bifunctional activity is owing to that optimized charge distribution facilitates the intermediates transformation. Aqueous ZABs based on MCC manifests high peak power density of 452 mW cm−2 and durable cycling stability of 1640 h. Quasi‐solid‐state ZABs based on MCC also show satisfactory performances (175 mW cm−2, 105 h). This work provides the route to develop efficient and durable electrocatalyst for constructing ZABs with long lifespan and high‐power‐density.

Nickel aluminum selenide wrapped by NiCoAl-layered double hydroxide enables a robust structure for supercapacitors

To explore a simple and convenient strategy for the construction of hybrid composites as advanced electrode materials for supercapacitors (SCs), this research realized the construction of nickel − aluminium selenide (NiAlSe)@NiCoAl-layered double hydroxide (NiCoAl-LDH) heterostructure. In-situ hybridization of NiCoAl-LDH nanosheets onto NiAlSe nanoparticles anchored on carbon cloth generates a special core–shell heterostructure, which enhances the exposure of active centers and increases the surface area. The formation of heterogeneous interfaces between NiAlSe and NiCoAl-LDH alters the electronic architecture and accelerates the electron/ion migration. By making full use of the structural benefits and the cooperative effect, the NiAlSe@NiCoAl-LDH composite electrode delivered a large capacitance (Cs) of 1789.2F/g at 1 A/g along with a high retention rate of 94.7 % over 5,000 cycles, which outperforms the bare NiAlSe and NiCoAl-LDH. Meanwhile, the assembled NiAlSe@NiCoAl-LDH hybrid supercapacitor (HSC) attained maximum specific energy (Es) of 71.5 Wh kg−1. This HSC device exhibits superior cyclic durability of 92.1 % after 30,000 cycles. Thereby, this research offers valuable insights into the construction of robust electrode materials for advanced HSC devices.

Co/CoOx–N–C bifunctional nanocatalyst derived from carbothermally optimized graphene networks with in-situ formed zeolitic imidazolate framework for high performance zinc-air batteries

Rechargeable zinc-air batteries are underpinned by high-performance and durable bifunctional oxygen electrocatalysts. Among the platinum-group metals (PGMs)-free catalysts, the redox-active cobalt-nitrogen-carbon (Co/CoOx–N–C) based materials are promising, however require further structural improvements. This work utilises extremely porous graphene networks (EGO) of hierarchical porosity to in-situ grow ZIF-67 nanocrystals extensively and homogeneously within the porous structure. A simple carbonization of nanoZIF-67@EGO not only generates finely dispersed redox capable Co/CoOx–N–C active sites with the help of residual oxygen functional groups of EGO, but also produces 2-3 dimensional hierarchical porous and conducting structure, readily facilitating high electrochemical surface area. This characteristic structure synergistically contributes to rapid charge and mass transfer rates along with high activity and stability for both ORR and OER. Here, it is worth mentioning that to produce equivalent catalyst material involving different graphitic or template supports requires prolonged and multi-step synthesis routes. The optimized catalyst delivers low potential difference of 0.86 V for bifucntional activity by offering superb ORR half-wave potential of 0.83 V vs RHE and limiting current density of 5.85 mA cm−2 in 0.1 M KOH electrolyte. Zinc-air battery exhibits peak power density of ∼175 mW cm−2 and specific capacity of ∼767 mAh g−1, along with durable cycling round trip efficiency of >63 % (correspond to low voltage gap of ∼0.74 V). These characteristics are better than numerous M–N–C based catalysts reported in the literature. This new strategy holds a great potential to boost the development of diverse MOFs and carbon-based electrocatalysts for a wide range of energy storage and conversion technologies.

Bringing multiscale dot-sheet heterostructured assembly into lignin valorization for efficient water desalination and zinc-ion hybrid capacitors

The notion of biomass valorization has been widely adopted to alleviate low-carbon-emission anxieties with the attributes in energy-environmental sustainability via groping multiscale-structured composite, yet still suffering from the dilemma of lignin upcycling. In this context, we propose a novel dot-sheet-assembled heterostructure featuring all lignin-derived bifunctional carbon composites (Co-N-C@CDs) that includes porous Co, N co-modified nanosheets and solvent-extracted carbon quantum dots. The photo-physical properties of lignin-based CDs are refined into multicolor green- and red-emissive fractions (GCDs and RCDs) via a facile biphasic fractionation. Owing to the high-graphite and conductivity, the red-emitting RCDs are installed with lamellar Co-N-C to favor the enlarged interlayer spacing, fast ionic intercalation-transfer and reversible chemical adsorption, thereby resulting in high-performance capacitive deionization (CDI) and zinc-ion hybrid capacitors (ZIHCs). While assembling the CDI device, the Co-N-C@CDs possess a maximum adsorption capacity of 33.64 mg g−1 NaCl in water desalination with stable restorable behavior. As the cathode of ZIHCs, it delivers an operating voltage of 2.0 V and superior energy density of 209.72 Wh kg−1, posing a long-term cycling durability at high current rates. Detailed hierarchical structure readily enables the large specific surface area, excellent percolating porosity, intercalated hydrogen bonds and redox active sites, which are conducive to not only expedite ionic infiltration and charge reaction kinetics but also reduce the energy barriers of aqueous ion adsorption. The multiscale 0D-2D supramolecular assembly breaks the frontier of lignin valorization to connecting energy-environment functions, thereby meeting the needs of carbon–neutral society.

Shape memory cyclic behavior and mechanical durability of woven fabric reinforced shape memory polymer composites

The shape memory cyclic behavior and mechanical durability of the shape memory polymer (SMP) and three woven fabrics (plain, twill, and satin weaves) reinforced shape memory polymer composite (WFR-SMPCs) are characterized to investigate the effect of woven textures on the mechanical and shape memory properties of WFR-SMPCs. Shape memory cycle test, shape memory durability test, and microscopic observation for SMP and WFR-SMPCs were carried out. Experimental results show that the SMP is temperature-sensitive, and higher temperature facilitates the shape memory performance of the material. The woven fabric reinforcements can significantly enhance the mechanical properties of the SMP matrix while still maintaining good shape recovery ratios above 98 % and shape fixation ratios above 90 % even though there is a slight decrease in these values. The twill WFR-SMPC displays the best mechanical performance. The satin WFR-SMPC has the highest shape recovery ratio. The twill WFR-SMPC performs the best in load-bearing capacity and recovery stress. The microscopic observations show that the rotational misalignment and bending of the fiber tows, and damage to the matrix are the main failure modes of the WFR-SMPCs at high shear strain.

Enhanced energy storage and mechanical properties in niobate-based glass-ceramics

The advancement of energy storage glass-ceramics, serving as quintessential elements within pulse power capacitors, is deemed essential for the progression of sophisticated electronic systems, attributable to their ultrafast discharge rate and elevated dielectric breakdown strength (DBS). In this study, the incorporation of 1.2 mol% Nd2O3 into SiO2-Na2O-K2O-BaO-Nb2O5-Nd2O3 (SNKBNN) glass-ceramics has significantly enhanced the material performance. Specifically, a high recoverable energy storage density (Wrec) of 2.06 J/cm3 can be achieved, alongside an ultrahigh efficiency (η) of 92.3 % under an electric field of 630 kV/cm. Additionally, this glass-ceramics also exhibit a high discharge energy density (Wd) of 0.97 J/cm3, an ultrafast discharge rate of 7 ns, and an exceptionally high hardness (Hv) of 10.51 GPa. Additionally, these glass-ceramics exhibit exceptional stability across a range of temperatures (25 to 150 ℃), frequencies (10 to 1000 Hz), and cycling durability (up to 104 cycles). The research has corroborated the structural interdependence between energy storage and mechanical properties, establishing a foundational understanding of their synergistic relationship. The synthesized glass-ceramics demonstrate significant potential for use in high-power dielectric capacitors.

The collaborative effect of Ni3S2-NiO heterojunction and porous carbon network modified lithium-sulfur battery separator for effectively inhibiting polysulfides shuttle

As an important part of lithium-sulfur battery (LSB), separator not only provides ion transport channel but also plays a key role in ensuring battery safety. However, the aperture of the commercial separator polypropylene (PP) is relatively large, which cannot effectively inhibit the migration of polysulfides generated during the charging and discharging process between the positive and negative electrodes, resulting in a decrease in the cycle stability of LSB. In this work, a modified LSB separator Ni3S2-NiO@AC-4@PP is designed, which is anchored by Ni3S2-NiO heterojunction on volcanic rock-like three-dimensional porous carbon network (AC) as the functional interlayer. The AC possesses a large specific surface area and excellent electrical conductivity, creating sufficient space for the physical and chemical adsorption of insoluble polysulfides. The Ni3S2-NiO heterojunction is embedded and attached to the AC, which helps to hinder the diffusion of polysulfides and accelerate the redox reaction. It is also confirmed by density functional theory (DFT) calculation that Ni3S2-NiO heterojunction inhibited the shuttle of polysulfides through the adsorption capacity of NiO and the catalytic activity of Ni3S2. Thus, the Ni3S2-NiO@AC-4@PP battery exhibits an elevated initial specific capacity of 1027.8 mAh g−1 at 0.2C, maintaining long-term stability after 200 cycles with the capacity retention rate of 81.4 %. At the higher current density (2C), Ni3S2-NiO@AC@PP battery demonstrates durable cycle with the capacity retention rate of 91.3 %. This study proposes a new feasible strategy to obtain high-performance, low-cost modified separators by designing functional interlayers with excellent adsorption and catalytic properties.

Mechanically Differentiated Lithium Versus Sodium Ion Storage in an Alloying‐Type Bismuth Anode

AbstractSodium‐ion battery (SIB) research benefits from lithium‐ion battery (LIB) studies due to Li and Na thermodynamic similarities. However, underneath these thermodynamic considerations lie kinetics factors leading to distinct Na+ versus Li+ storage mechanisms even within the same electrode materials, which is ascribed to either ionic size variations or diffusion path differences. Herein, the library of such non‐negligible factors is extended by targeting an alloying‐type bismuth anode well known for its high volumetric capacity for both Li+ and Na+ storage, showing that the mechanical property of key reaction intermediates also plays a role in differentiating its Na+ versus Li+ storage mechanisms. Applying spatially and temporally resolved in situ transmission electron microscopy to Li+ and Na+ storage within bismuth, it not only demonstrates the thermodynamic similarity in a step‐wise phase transition but also discloses its kinetic distinctions in morphological and structural integrities determined by Young's modulus of involving reaction intermediates and spatial configuration, which well accounts for the surprisingly observed superior Na+ storage performance of Bi anode compared to the inferior Li+ storage. Findings here highlight the role of reaction intermediates’ mechanical properties in regulating the overall cycling durability of electrode materials, and guide future material engineering toward performance enhancement, particularly for SIBs.

Development of Ti–Zr–Mn–Cr-(V–Fe) based alloys for hydrogen feeding system in hydrogen metallurgy application

AB2-type Ti-based hydrogen storage alloys are considered promising candidates for the hydrogen feeding system in hydrogen-metallurgy application. In this work, Ti0·87Zr0.15MnxCr1.75-xV0.25 (x = 1.25–1.5), Ti0·87Zr0·15Mn1·5Cr0.5-y(VFe)y (y = 0.25–0.43) and Ti0.85+zZr0.15Mn1·5Cr0·07(VFe)0.43 (z = 0–0.05) alloys were synthesized using induction levitation melting, where ferrovanadium VFe consists of 80 wt% V and 20 wt% Fe. Subsequently, their microstructures and hydrogen storage performances were systematically investigated. The results demonstrate that all alloy samples exhibit a single C14 Laves phase structure with uniform element distribution. With the increment of Cr/Mn, VFe/Cr ratio, or Ti stoichiometry, the alloys exhibit enhanced hydrogen storage capacity, accompanied by a decrease in hydrogenation equilibrium pressure because of interstitial volume expansion or hydrogen affinity improvement, which is also supported by density functional theory calculations. Considering the application of hydrogen metallurgy, Ti0·86Zr0·15Mn1·5Cr0·07(VFe)0.43 alloy is regarded as a promising candidate, exhibiting a saturated capacity of 2.01 wt% H2, an effective reversible capacity of 1.91 wt% H2, rapid hydrogenation kinetics, excellent cyclic durability and low costs. This work provides valuable insights into the compositional design of hydrogen storage alloys for the hydrogen feeding system in hydrogen metallurgy applications.

Integration of vanadium diphosphide with 2D cobalt phosphide architected as an extensible redox active positrode for alkaline supercapacitor

Metal phosphides in the form of rationally constructed two-dimensional (2D) nanosheets hold significant promise as versatile materials for energy storage applications. This study introduces a novel hybrid supercapacitor electrode, composed of a binder-free vanadium phosphide integrated cobalt phosphide (VP@CP) on a nickel foam substrate. The fabrication process involves the hydrothermal growth of Co2(OH)2BDC (BDC- 1,4-benzenedicarboxylate) nanosheets on a Ni-foam substrate (CMF-Ni), followed by the deposition of VO2 on CMF nanosheets (VO@CMF-Ni) using chronoamperometry and phosphorization of the VO@CMF-Ni to yield VP@CP-Ni nanosheets. Particularly, the density functional theory (DFT) results show that the VP2 integrated Co2P sample provides metallic behavior and low adsorption energy of OH− ions, resulting in improved electrochemical redox process. These bimetallic phosphides exhibit outstanding properties, including enhanced pathways for rapid ion transport and storage, increased electronic conductivity, and expanded electroactive regions facilitating the faradaic charge storage process. Due to the presence of vanadium and cobalt coupled sites, the fabricated VP@CP-Ni electrode was able to attain a maximum areal capacity (CAR) of 971 mA h cm−2 at 6 mA cm−2. Additionally, the fabricated hybrid device (HDC) exhibits an impressive specific energy (SE) of 30.9 Wh kg−1 at a specific power (SP) of 1344 W kg−1, and excellent cyclic durability. These remarkable results stimulate the exploration of such possible 2D VP@CP-Ni nanosheets with promising charge storage electrode capabilities to develop a future era of energy storage devices.

Multicomponent hierarchical Cu-based advanced cathode for ultrahigh capacity rechargeable Cu-Zn battery

Rechargeable aqueous Zn-based batteries (RAZBs) have emerged as a practically attractive option for large-scale energy storage applications due to their cost-effectiveness, safety, eco-friendliness, and high theoretical capacity. Nonetheless, the application of RAZBs at the grid scale is restricted by the drawbacks of cathode that exhibit low capacities and poor durability. In this work, a multicomponent hierarchical Cu@CuO@Cu2O cathode with superior electrochemical energy storage performance has been successfully synthesized by a fairly simple calcination method. Benefiting from its large active area, fast ion diffusion channel, high conductivity, and synergetic effect between different components, the resulting Cu@CuO@Cu2O electrode exhibits ultrahigh specific capacity (40.2 mAh cm−2, 402 mAh cm−3 at 10 mA cm−2), excellent rate capability (24.8 mAh cm−2, 248 mAh cm−3 at 100 mA cm−2) and satisfactory cycling durability (71.5 % capacity retention after 3800 cycles). To our knowledge, such high areal/volumetric specific capacity ranks top among previously reported Cu-based electrode and other aqueous electrodes. Furthermore, the fabricated Cu@CuO@Cu2O//Zn battery achieves an extraordinary energy density of 24.5 mWh cm−2 and a remarkable cyclic capability of 91 % capacity retention after 3000 cycles, highlighting its potential for large-scale energy storage in RAZBs.

Chemically Stable NiMoO4/NRGO Asymmetric Capacitor

AbstractIn this work, a chemically stable NiMoO4/NRGO nanocomposite was prepared via a facile hydrothermal method. The flower‐like structure of NiMoO4 (NMO) nanoparticles is randomly distributed on the surface of nitrogen‐doped reduced graphene oxide (NRGO) sheets, as observed in FESEM images. Compared to related reports, the NMO/NRGO (II) nanocomposite exhibits an excellent high surface area of 368.9 m2 g−1 and a mesoporous nature, as shown in N₂ adsorption‐desorption isotherms. The specific capacitance of the NMO/NRGO (II) electrode is 721 F g−1 at 1 A g−1 using a 6 M KOH electrolyte, retaining 91.2 % of its initial value after 5000 cycles. Electrochemical impedance spectroscopy (EIS) reveals that the electrode has a lower charge‐transfer resistance, indicative of good electrochemical behavior. An asymmetric device consisting of NMO/NRGO (II) || activated carbon (AC) electrodes exhibits a high energy density of 49.1 Wh kg−1 at 524.4 W kg−1 within a voltage range of 1.4 V, retaining 89 % of its initial capacitance after 5000 cycles, demonstrating good cyclic durability. These results suggest that the NMO/NRGO (II) electrode is a promising active material for supercapacitor devices.

Crystalline/Amorphous Co2P2O7 cathode with outstanding areal capacity for High-Performance Zinc-Cobalt battery

It is still a challenge to develop aqueous rechargeable Zn-based alkaline batteries with high energy density, power density and excellent stability. Herein, a crystalline/amorphous Co2P2O7 self-supporting on the Ni foam is fabricated as a cathode material of aqueous Zn-based alkaline batteries. The unique crystalline/amorphous structure endows the electrode material with more exposed active sites, higher redox species coverage, larger electrochemical surface area (ECSA), smaller charge-transfer resistance, lower reaction energy barriers and faster electrochemical reaction kinetics process, which clarifies an explicit structure–property relationship simultaneously. As a result, the crystalline/amorphous Co2P2O7 (CP-P-450) electrode assembled as CP-P-450//Zn battery achieves an extraordinary areal capacity of 2.49 mAh cm−2 at 5 mA cm−2, satisfactory rate performance, excellent cyclic durability (96.6 % retention after 4000 cycles) and impressive energy density (4.16 mAh cm−2) and peak power density (115.94 mW cm−2). The quasi-solid CP-P-450//Zn battery can drive a variety of electrical appliances working well even under abuse tests, demonstrating excellent safety and application potential. This study provides an effective strategy towards excellent comprehensive energy storage performance of aqueous Zn-based alkaline batteries through structuring the crystalline/amorphous phase in cathodes.