Construction of 2D sandwich-like Na2V6O16·3H2O@MXene heterostructure for advanced aqueous zinc ion batteries

Boosting Iodine Redox Kinetics by Nickel-Cobalt Diatomic Electrocatalyst for Zinc-Iodine Batteries

Single-atom catalysts (SACs) offer an efficient solution of a well-defined structure-activity relationship for boosting iodine redox kinetics and suppressing the shuttle effect in zinc-iodine (Zn-I2) batteries, but the further upgradation of their electrocatalytic activity is still constrained to date. Herein, atomically dispersed transition-metal electrocatalysts comprised of heteronuclear nickel-cobalt diatomic sites anchored on porous carbon nanosheets (Ni-Co-DA/PCNs) are proposed by a novel interlayer-confinement pyrolysis strategy. Thereinto, the NiCoAl-layered double hydroxides are employed as the 2D topological structure to induce the confined polycondensation of aromatic hydrocarbon precursors, and the transition-metal ions are simultaneously trapped in hierarchical carbon frameworks by the oxygen-containing species. The detailed experimental investigations combined with the in situ Raman spectroscopy reveal that the Ni-Co-DA/PCNs electrocatalyst with well-defined M-O4 pair and high specific surface area is capable of facilitating the adsorption and fast conversion of polyiodides, thereby accelerating the redox kinetics of I2/I‒ and protecting zinc anode. Consequently, the assembled Zn-I2 batteries with the Ni-Co-DA/PCNs/I2 cathode exhibit a high discharge capacity of 216.7 mAh g‒1 at 0.2 A g‒1 with excellent rate capability and ultralong cycling lifespan over 9000 cycles with a capacity decay of only 0.0018% per cycle, which is far superior to those of Ni/Co SACs. This work provides a new insight into the design of dual-atom catalysts for Zn-halogens batteries.

Sandwich-Like MXene@Mn3O4@PPy Hollow Microspheres Synergistically Enabled Ultra-long Cycling Life in Aqueous Zinc Ion Batteries

Manganese-based oxides are be regarded as one of the most promising cathode materials for aqueous zinc ion batteries (AZIBs). A major restriction of manganese-based oxides in practical applications is their unsatisfied structural stability due to the irreversible manganese dissolution. Additionally, the poor electrical conductivity also limits the rate capability. Herein, the sandwich-like MXene@Mn3O4@PPy hollow microspheres are constructed via self-sacrificial template and surface coating method to improve the cycling life of AZIBs. Benefiting from the unique sandwich-like hollow structure and the surface coating of PPy, the MXene@Mn3O4@PPy cathode possesses high electronic/ionic conductivity and satisfied structural stability. The sandwich-like MXene@Mn3O4@PPy hollow microspheres deliver excellent electrochemical performance, including an impressive rate capability and ultra-long cycling life with a capacity of 120 mAh g-1 at 5 A g-1 after 9000 cycles. In addition, the systematic ex situ XRD and HRTEM characterizations verify the highly reversible Zn2+ and H+ insertion/desertion in the sandwich-like MXene@Mn3O4@PPy hollow microspheres. This work combines hollow structure design and surface coating method to provide an effective strategy for improving the structural stability of manganese-based oxides in AZIBs.

Deciphering the energy storage mechanism of CoS2 nanowire arrays for High-Energy aqueous copper-ion batteries

Transition metal sulfide (TMs) offers ultra-high specific capacity through multi-electron transfer, showing promise for aqueous batteries. However, the poor cycling performance and the uncleared energy storage mechanism are restricted from further development. Herein, CoS2 nanowire arrays grown on carbon cloth (CoS2/CC) are proposed as binder-free and self-supporting electrodes for aqueous copper-ion batteries. The energy storage mechanism is clarified by a series of ex-situ tests: a multi-electron electrode reaction through a three-step reaction of CoS2 → CuS → Cu7S4 → Cu2S. Electrochemical results suggest that the CoS2/CC cathode exhibits excellent long cycle stability (capacity retention of 99.7 % after 1000 cycles at 10 A/g) along with high specific capacity (762.3 mAh g-1 at 1 A/g). The carbon cloth with stable three-dimensional (3D) conductive structure can not only offer high-speed pathways to promote the transfer of electrons but also inhibit the volume change. Meanwhile, CoS2 nanowire arrays with high surface-to-volume ratios can improve wettability of electrolyte and promote redox reactions. Furthermore, an advanced Zn-CoS2/CC hybrid ion aqueous battery reveals an energy density of 724 Wh kg-1 and an output voltage of 1.24 V, providing a promising strategy for the establishment of transition metal sulfide cathode in high-energy aqueous batteries.

Sodium Vanadates for Metal-Ion Batteries: Recent Advances and Perspectives

Rechargeable metal-ion batteries (MIBs) play a pivotal role in advancing the stable supply of renewable energy by efficiently storing and discharging electrical energy. In recent years, to propel the continuous advancement of MIB technology, numerous studies have concentrated on exploring and innovating electrode materials, aiming to engineer commercial batteries with high energy density, superior power density, and extended cycle life. Notably, sodium vanadates have garnered significant attention in the realm of MIBs owing to their distinctive crystal structures, abundant resource reservoirs, and exceptional electrochemical properties. This paper provides a prompt and comprehensive review of the research landscape for various sodium vanadates (such as NaxV2O5, Na1+ xV3O8, Na2V6O16·xH2O, etc.) in the domain of MIBs over the past five years. It delves into the structural characteristics, electrochemical performances, and energy storage mechanisms of these materials, while also proposing some effective strategies to augment their electrochemical capabilities. Building upon these insights and prevailing research outcomes, this review envisions the future developmental pathways of sodium vanadates for MIBs and aims to reveal the vast potential of sodium vanadates in the emerging energy storage field and provide researchers with clear insights and perspectives for developing optimal sodium vanadate electrodes.

Mxene and GaIn Alloy Nanostructures Regulate Zn Surface Ion Deposition for High-Performance Zinc-Ion Battery

Zinc is an ideal energy storage material because of its low toxicity, nonflammability, and good biocompatibility. However, the commercial application is seriously hindered due to problems such as dendrite growth, hydrogen evolution, and interface passivation caused by "dead zinc" in the process of cyclic deposition. Herein, a nanoscale deposition dispersion model is designed in order to achieve directional deposition and uniform distribution of zinc ions for the growth of interfacial dendrites. Liquid metal GaIn was combined with Mxene for this nanostructure, which provides a rapid ion transfer channel to achieve lower overpotentials, a more uniform electric field distribution, and stronger corrosion resistance in a core-shell structure to achieve interface reaction suppression. The material was coated on the surface of the zinc metal as an artificial protective layer. It has a better cycle life at 1 mA·cm-2 compared with the bare Zn metal anode, achieving a long cycle time of 1100 h and an ultralow voltage lag (28.1 mV). It maintains the stability for 1000 cycles at 1 mA·cm-2 after assembling the complete battery. This provides a way to improve the performance of zinc-ion secondary batteries and paves the way for the next generation of energy storage devices.

Recent Progress in the Applications of MXene-Based Materials in Multivalent Ion Batteries

Multivalent-ion batteries have garnered significant attention as promising alternatives to traditional lithium-ion batteries due to their higher charge density and potential for sustainable energy storage solutions. Nevertheless, the slow diffusion of multivalent ions is the primary issue with electrode materials for multivalent-ion batteries. In this review, the suitability of MXene-based materials for multivalent-ion batteries applications is explored, focusing onions such as magnesium (Mg2+), aluminum (Al3+), zinc (Zn2+), and beyond. The unique structure of MXene offers large interlayer spacing and abundant surface functional groups that facilitates efficient ion intercalation and diffusion, making it an excellent candidate for multivalent-ion batteries electrodes with excellent specific capacity and power density. The latest advancements in MXene synthesis and engineering techniques to enhance its electrochemical performance have been summarized and discussed. With the versatility of MXenes and their ability to harness diverse multivalent ions, this review underscores the promising future of MXene-based materials in revolutionizing the landscape of multivalent-ion batteries.

MXene: A Roadmap to Sustainable Energy Management, Synthesis Routes, Stabilization, and Economic Assessment

MXenes with their wide range of tunability and good surface chemistry provide unique and distinctive characteristics offering potential employment in various aspects of energy management applications. These high-performance materials have attracted considerable attention in recent decades due to their outstanding characteristics. In the literature, most of the work is related to specific methods for the preparation of MXenes. In this Review, we present a detailed discussion on the synthesis of MXenes through different etching routes involving acids, such as hydrochloric acid, hydrofluoric acid, and lithium fluoride, and non-acidic alkaline solution, electrochemical, and molten salt methods. Furthermore, a concise overview of the different structural, optical, electronic, and magnetic properties of MXenes is provided corresponding to their role in supporting high thermal, chemical, mechanical, environmental, and electrochemical stability. Additionally, the role of MXenes in maintaining the thermal management performance of photovoltaic thermal systems (PV/T), wearable light heaters, solar water desalination, batteries, and supercapacitors is also briefly discussed. A techno-economic and life cycle analysis of MXenes is provided to analyze their sustainability, scalability, and commercialization to facilitate a comprehensive array of energy management systems. Lastly, the technology readiness level of MXenes is defined, and future recommendations for MXenes are provided for their further utilization in niche applications. The present work strives to link the chemistry of MXenes to process economics for energy management applications.

Micro-mesoporous cobalt phosphosulfide (Co3S4/CoP/NC) nanowires for ultrahigh rate capacity and ultrastable sodium ion battery

The construction of heterostructure materials has been demonstrated as the promising approach to design high-performance anode materials for sodium ion batteries (SIBs). Herein, micro-mesoporous cobalt phosphosulfide nanowires (Co3S4/CoP/NC) with Co3S4/CoP hetero-nanocrystals encapsulating into N-doped carbon frameworks were successfully synthesized via hydrothermal reaction and subsequent phosphosulfidation process. The obtained micro-mesoporous nanowires greatly improve the charge transport kinetics from the facilitation of the charge transport into the inner part of nanowire. When evaluated as SIBs anode material, the Co3S4/CoP/NC presents outstanding electrochemical performance and battery properties owing to the synergistic effect between Co3S4 and CoP nanocrystals and the conductive carbon frameworks. The electrode material delivers outstanding reversible rate capacity (722.33 mAh/g at 0.1 A/g) and excellent cycle stability with 522.22 mAh/g after 570 cycles at 5.0 A/g. Besides, the Ex-situ characterizations including XRD, XPS, and EIS further revealed and demonstrated the outstanding sodium ion storage mechanism of Co3S4/CoP/NC electrode. These findings pave a promising way for the development of novel metal phosphosulfide anodes with unexpected performance for SIBs and other alkali ion batteries.

Heterojunction tunnelled vanadium-based cathode materials for high-performance aqueous zinc ion batteries

Rechargeable aqueous zinc ion batteries (ZIBs) have emerged as a promising alternative to lithium-ion batteries due to their inherent safety, abundant availability, environmental friendliness and cost-effectiveness. However, the cathodes in ZIBs encounter challenges such as structural instability, low capacity, and sluggish kinetics. In this study, we constructed BiVO4@VO2 (BVO@VO) heterojunction cathode material with bismuth vanadate and vanadium dioxide phases for ZIBs, which demonstrate significant advancements in both aqueous and quasi-solid-state ZIBs. Benefitting from the heterojunction structure, the materials present a high capacity of 262 mAh g-1 at 0.1 A g-1, superb cyclic stability with 96% capacity retention after 1000 cycles at 2 A g-1, and outstanding rate property with a specific capacity of 218 mAh g-1 even at a high rate of 5.0 A g-1. Furthermore, the flexible quasi-solid-state ZIBs incorporating the BVO@VO cathode demonstrate prolonged cyclic life performance with a remarkable specific capacity of 234 mAh g-1 over 100 cycles at a current density of 0.1 A g-1. This study potentially paves the way for the utilization of heterointerface-enhanced zinc ion diffusion for vanadium-based materials in ZIBs, thereby providing a new approach for the design and investigation of high-performance zinc-ion systems.

Cobalt-vanadium sulfide yolk-shell nanocages from surface etching and ion-exchange of ZIF-67 for ultra-high rate-capability sodium ion battery

Development of high-performance metal sulfides anode materials is a great challenge for sodium-ion batteries (SIBs). In this work, a cobalt-based imidazolate framework (ZIF-67) were firstly synthesized and applied as precursor. After the successive surface etching, ion exchange and sulfidation processes, the final cobalt-vanadium sulfide yolk-shell nanocages were obtained (CoS2/VS4@NC) with VS4 shell and CoS2 yolk encapsulated into nitrogen doped carbon frameworks. This yolk-shell nanocage structure effectively increases the specific surface area and provides enough space for inhibiting the volume change during charge/discharge processes. Besides, the nitrogen doped carbon skeleton greatly improves the ionic conductivity and facilitates ion transport. When used as the anode materials for SIBs, the yolk-shell nanocages of CoS2/VS4@NC electrode exhibits excellent rate capability and stable cycle performance. Notably, it displays a long-term cycling stability with excellent capacity of 417.28 mA h g-1 after 700 cycles at a high current density of 5 A/g. This developed approach here provides a new route for the design and synthesis of various yolk-shell nanocages nanomaterials from enormous MOFs with multitudinous compositions and morphologies and can be extended to the application into other secondary batteries and energy storage fields.

Synergistic enhancement of chemisorption and catalytic conversion in lithium-sulfur batteries via Co3Fe7/Co5.47N separator mediator

Lithium-sulfur batteries (LSBs) show considerable potential in next-generation high performance batteries, but the heavy shuttle effect and sluggish redox kinetics of polysulfide hinder their further applications. In this paper, to address these shortcomings of LSBs, Co3Fe7/Co5.47N heterostructure were prepared and constructed from their Fe-Co Prussian blue analogue precursors under the condition of high temperature pyrolysis. The obtained Co3Fe7/Co5.47N display excellent immobilization-diffusion-conversion performance for polysulfides by synergistic effect in successfully hindering the shuttle effect of polysulfides. When the Co3Fe7/Co5.47N heterostructure were applied to modify the commercial polypropylene (PP) separator, the batteries displayed fantastic rate capacity and cycling stability. Specifically, the Co3Fe7/Co5.47N-PP batteries exhibit an extremely satisfactory initial specific capacity of 1430 m Ah/g at 0.5C, wonderful rate capacity of around 780 m Ah/g at 3C and superior per cycle decaying rate of 0.08 % for 500 cycles at 0.5C. When the current density reaches to 2C, the batteries still exhibit 501 m Ah/g after 900 cycles with 0.015 % per cycle decay rate. Besides, even in the high loading of sulfur (3.0 mg cm-2) at 0.5C, the superior cycling stability (0.075 % per cycle decay rate after 200 cycles) and high specific capacity (741 mAh/g after 200 cycles) can still be performed. Thus, this work provides a facile method for high-powered and long-life Li-S batteries with eminent entrapping-conversion processes of polysulfides.