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The high electronic conductivity and tailorable structural properties of MXene materials make them promising candidates for energy storage. However, their poor chemical instability and self‐stacking effect greatly limit their application, especially in aqueous systems. Here, using a eutectic etching approach, hydroxylated borophene is used as a trifunctional mediator to construct robust Ti3C2Tx‐based MXene/B self‐assembled film electrodes for zinc‐ion capacitors (ZICs). Due to this mediator, the as‐formed strong interfacial binding within the heterostructure can give rise to an integrated modification effect and promote high‐efficiency interface energy storage. One is to strengthen the thermodynamic stability of local Ti─O bonds and inhibit the irreversible degradation of MXene; two is to enlarge the interface space of the MXene electrode and boost the ion transport; three is to improve the interfacial Zn2+ trapping ability without affecting Zn2+ migration on the MXene surface. Thus, the MXene/B electrode exhibits a high areal capacitance (537.9 mF cm−2) at a current density of 0.2 mA cm−2 and an extraordinary cycling stability at 1 mA cm−2, with 99.64% retention after 40 000 cycles, which far surpasses that of most previous reports. This work provides a pathway for overcoming the interface storage limit of MXene electrodes to construct high‐performance ZICs. [ABSTRACT FROM AUTHOR]

Mesophase microporous carbon spheres (MMCS), are the anode materials of spent lithium‐ion batteries (LIB), existing in large amounts on the earth that result in resource wastes and ecological pollution. In order to utilize the above waste resources, a new idea of recycling scrapped LIB anode materials was exploited to apply for capacitive deionization (CDI). Herein, the activated microporous carbon spheres (AMCS) were synthesized by a one‐step KOH activation of mesophase microporous carbon spheres (MMCS). By controlling the weight ratios of KOH to MMCS, the fabricated AMCS with the optimal specific surface area of 2626 m2 g−1 and the pore volume of 0.98 cm3 g−1 were fabricated. The AMCS3‐1 with a weight ratio of KOH to MMCS of 3 : 1 exhibits higher specific capacitance (196.9 F g−1) and lower charge transfer resistance. Importantly, the AMCS3‐1 electrode demonstrates excellent electrosorption capacity of 12.73 mg g−1 and fast salt adsorption rate of 2.64 mg g−1 min−1 at 1.2 V. In addition, the excellent repeatability over 50 regeneration cycles could be obtained for AMCS3‐1 electrode compared with commercial activated carbon electrode. The results reveal that the AMCS3‐1 is a promising candidate as high‐performance electrodes for CDI. The strategy of recycling MMCS from waste LIB anode materials for CDI is desirable, which displays great potential in the removal of sodium chloride (NaCl). [ABSTRACT FROM AUTHOR]

Summary: Porous Fe2O3 nanostructures were synthesized through electrospinning of Fe (NO3)3/polyvinylpyrrolidone followed by calcination in air. The morphology of the resultant Fe2O3 was tuned by changing the ratio between Fe (NO3)3 and the polymer matrix. The performance of these nanostructures as counter electrodes in dye‐sensitized solar cells (DSSCs) was investigated. It was found that nanotubes exhibit significantly higher catalytic efficiency toward reducing I−/I3− electrolytes than nanorods and nanobelts, showing a photoelectric conversion efficiency of 4.0%, also superior to a range of transition metal oxides. Furthermore, the nanotube‐based counter electrode showed lower resistance than other Fe2O3 nanostructures. These results were attributed to the high specific surface area (90.2 m2 g−1) of the nanotubes, which provides a large reaction site and can promote the charge transfer at the electrode/electrolyte interfaces. The low cost and ease of mass production make Fe2O3 nanotube a promising candidate to replace Pt as the counter electrode in DSSCs. [ABSTRACT FROM AUTHOR]

Abstract: The sluggish sodium reaction kinetics, unstable Sn/Na2O interface, and large volume expansion are major obstacles that impede practical applications of SnO2‐based electrodes for sodium‐ion batteries (SIBs). Herein, we report the crafting of homogeneously confined oxygen‐vacancy‐containing SnO2−x nanoparticles with well‐defined void space in porous carbon nanofibers (denoted SnO2−x/C composites) that address the issues noted above for advanced SIBs. Notably, SnO2−x/C composites can be readily exploited as the working electrode, without need for binders and conductive additives. In contrast to past work, SnO2−x/C composites‐based SIBs show remarkable electrochemical performance, offering high reversible capacity, ultralong cyclic stability, and excellent rate capability. A discharge capacity of 565 mAh g−1 at 1 A g−1 is retained after 2000 cycles. [ABSTRACT FROM AUTHOR]

The performance of dye-sensitized solar cells (DSSCs) is critically dependent on the catalytic activity of their counter electrode (CE) materials. There are great research interests to develop alternative CE materials to replace the conventional Pt electrode. Herein, nickel cobalt sulfide (NiCoS, NCS) particles were prepared through sulfurization of NiCoO (NCO) electrospun nanofibers. The bimetallic sulfide was used as CE for DSSC and exhibited an excellent photoenergy conversion efficiency (PCE) of 7.12%, which is higher than the dye-sensitized solar cells using NCO (5.24%) and Pt CEs (7.05%). Systematic electrochemical characterization suggests that this extraordinary performance of NCS might be related to the improved electrocatalytic ability and electrical conductivity. In view of the low-cost synthesis and outstanding electrochemical performance, the NCS counter electrode would hold great promise for applications in dye-sensitized solar cells. [ABSTRACT FROM AUTHOR]

The performance of a dye-sensitized solar cell (DSSC) is strongly influenced by the catalytic performance of its counter electrode (CE) materials. Platinum (Pt) is conventionally used as the CE for DSSCs, but it is precious and is readily corroded by the iodide/triiodide electrolyte. Herein, mesoporous NiCo2O4 networks with different types of building blocks were prepared by electrospinning of a composite solution followed by annealing in air, and their performances as CEs in DSSCs were investigated. The honeycomb-like NiCo2O4 exhibited better performance than the nanotube ones, showing a photoelectric conversion efficiency of 7.09% which is higher than that of a standard Pt CE (7.05%) under the same conditions. The enhanced electrode performance was attributed to the relatively larger surface area and higher conductivity. The preparation methods demonstrated in this study are scalable and would pave the way for practical applications of Pt-free DSSCs. [ABSTRACT FROM AUTHOR]

Nickel sulfides (NiSs) with different morphologies (nanocubes, flower-like structure, and nanospheres) have been synthesized on fluorinated tin oxide glass (FTO) substrate using a hydrothermal method, which can be used as transparent counter electrodes (CEs) for dye-sensitized solar cells (DSSCs). The morphology of NiSs can be easily tailored by using different surfactants, and the flower-like NiS structure displays remarkable electrocatalytic activity for reducing I . Therefore, the flower-like NiS CE used in DSSCs generates higher photoelectric conversion efficiency (7.10 %) which is comparable with Pt (7.05 %) under the same conditions. This work paves the way for the substitution of noble metal Pt by the flower-like NiS for CE in DSSCs in the future. [ABSTRACT FROM AUTHOR]

The design of electrode compatible with wide‐temperature, fast‐charging, and long‐lifespan aqueous zinc‐ion batteries is a great challenge that urgently needs addressing. However, the mismatch between runaway host dissolution and high interfacial hydrophilicity within electrode is a contradictory problem that restricts their electrochemical performance. In this report, take the typical vanadium diselendie (VSe2) host for example, by employing the natural polymer bacterial cellulose (BC) as the multifunctional mediator, a design paradigm of self‐assembly hybrid electrode with efficient tandem electrochemistry is presented. Theoretical and experimental research confirmed that such BC‐mediated hybrid structure exhibits multiple functions to well balance the cathode dissolution and storage kinetics. Impressively, such an electrode displayed an excellent rate capability (1–50 A g−1), and an unexpected record‐lifespan of 45 000 cycles. Beyond that, it also shows a good temperature‐tolerance ability, remaining the high specific capacities of 120 and 288 mAh g−1 (at 10 A g−1) after 3000 cycles at −25 and 50 °C, respectively. Note that such approach is also applicable to the high‐voltage platform MnO2 and I2 hosts, demonstrating its potential for universality. This discovery can provide a new design principle of robust electrode for advanced aqueous zinc‐ion batteries. [ABSTRACT FROM AUTHOR]

A novel approach of carbonizing leaves by thermal pyrolysis with melt diffusion followed by selenium vapor deposition is developed to prepare the carbon-selenium composite cathodes for sodium-selenium batteries. The carbonized leaf possesses internal hierarchical porosity and high mass loading; therefore, the composite is applied as a binder- and current collector-free cathode, exhibiting an excellent rate capability and a high reversible specific capacity of 520 mA h g−1 at 100 mA g−1 after 120 cycles and 300 mA h g−1 even at 2 A g−1 after 500 cycles without any capacity loss. Moreover, the unique natural three-dimensional structure and moderate graphitization degree of leaf-based carbon facilitate Na+/e− transport to activate selenium which can guarantee a high utilization of the selenium during discharge/charge process, demonstrating a promising strategy to fabricate advanced electrodes toward the sodium-selenium batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Vertically aligned ZnO hexagonal columns are grown on Zn foil via a solution method. • The aligned ZnO columns can guide oriented Zn plating due to low lattice mismatch. • The Zn plating tends to occur along (0 0 2) facet associated with parallel plating. • The Zn metal corrosion and harmful side reactions can be effectively inhibited. • The cyclability of Zn//Zn cell and Zn//MnO 2 batteries can be significantly improved. Aqueous zinc-ion batteries (AZIBs), featuring low cost and high safety, have become a research hotspot in recent years. However, the low Zn stripping/plating reversibility, caused by dendritic growth, harmful side reactions, and Zn metal corrosion, severely influences the applicability of AZIBs. Zincophilic materials have shown great potential to form protective layers at the surface of Zn metal electrodes, whereas those protective layers are usually thick, lack fixed crystalline orientation, and require binders. Herein, a facile, scalable, and cost-effective solution method is used to grow vertically aligned ZnO hexagonal columns with (0 0 2) top surface and low thickness of 1.3 µm onto Zn foil. Such oriented protective layer can promote homogenous and nearly horizontal Zn plating not only on the top but also at the side of ZnO columns due to the low lattice mismatch between Zn (0 0 2) and ZnO (0 0 2) facets and between Zn (1 1 0) and ZnO (1 1 0) facets. Accordingly, the modified Zn electrode exhibits dendrite-free behavior with considerably suppressed corrosion issue, inert byproduct growth, and hydrogen evolution. Thanks to that, the Zn stripping/plating reversibility is significantly improved in Zn//Zn cell, Zn//Ti cell, and Zn//MnO 2 battery. This work provides a promising avenue for guiding metal plating process via oriented protective layer. [ABSTRACT FROM AUTHOR]

[Display omitted] • A design concept of sandwich-like Ti 3 C 2 T x MXene-bridged VO 2 heterostructure (VO 2 /Ti 3 C 2 T x) was proposed. • The VO 2 /Ti 3 C 2 T x electrode can retain a specific capacity of 170 mAh g−1 at 5 A g−1 after 1500 cycles. • Such heterogeneous engineering can relieve self-aggregation and boost interfacial storage kinetics of electrode. • Phase transformation with a highly reversible H+/Zn2+ insertion/extraction behavior was uncovered. Severe aggregation and sluggish reaction kinetics are the main research challenges that impair the storage performance of cathode materials for aqueous zinc-ion batteries. In this work, we report the concept of sandwich-like Ti 3 C 2 T x MXene-bridged VO 2 heterostructure (VO 2 /Ti 3 C 2 T x) design to simultaneously relieve the self-aggregation and boost the interfacial storage kinetics. When acting as cathode material, such VO 2 /Ti 3 C 2 T x electrode can deliver a high specific capacity 415 mAh g−1 at 0.1 A g−1 after 110 cycles, as well as 338 mAh g−1 at 1 A g−1 after 300 cycles, much higher than that of the pure VO 2 case. Moreover, such electrode also exhibits remarkably rate capability and cyclic stability, which can retain a specific capacity of 170 mAh g−1 at the high current density of 5 A g−1 after 1500 cycles. The superior storage performance should be mainly benefited from the mixed-dimensional heterogeneous engineering. In addition, the evolution of crystal structure and valence state of electrode upon cycling were investigated, thus a storage mechanism can be revealed. That is, single VO 2 phase would be transformed into the VO 2 and Zn x V 2 O 5 ·nH 2 O mixed phase, with a highly reversible H+/Zn2+ insertion/extraction behavior. Such strategy proposed in this work can be also applied for other kinds of cathode materials and promoting the development of aqueous zinc-ion batteries. [ABSTRACT FROM AUTHOR]

Abstract: Ag–Sb composite anode was prepared by chemical reductive method. The structure, morphology, chemical composition and electrochemical properties of synthesized Ag–Sb composite anode were evaluated by XRD, FE-SEM, EDS and galvanostatical charge–discharge tests. The results indicated that the changes of structure and volume were alleviated effectively by using metal phase instead of intermetallic phase and restraining the lithiation reaction of Ag at high current density (0.2mAcm−2). The electrochemical reactions took place in a stable and highly conductive Ag framework, which ensured the good cyclability of the Ag–Sb composite electrode. [Copyright &y& Elsevier]

Developing novel nanostructures is always the most decisive aspect for high-performance supercapacitor electrodes. Thus, a facile one-step and self-templated method is successfully developed for the fabrication of urchin-like Ni 2 Co(CO 3) 2 (OH) 2 hollow microspheres (NiCoHSs) as a high-performance hybrid supercapacitor electrodes. The synthesis conditions are carefully adjusted and the mechanisms of morphology transformation are clearly illustrated. The favorable morphology with a large specific surface area, suitable pore sizes, and good conductivity endows a high specific capacity (890.8 C g−1 at 0.5 A g−1) and excellent rate retention (700.8 C g−1 at 50 A g−1), and high stability (87.5% over 5000 cycles), which outperforms most reported electrodes based on nickel-cobalt oxides/hydroxides. Contributed by the uniquely engineered electrodes, a high-performance hybrid supercapacitor (HCS) is assembled, which exhibited a high specific capacity of 256.9 C g−1 (160.5 F g−1) at 0.5 A g−1 with an operating voltage of 1.6 V and an outstanding energy density of 57.1 W h kg−1 at a power density of 400.0 W kg−1. This work offers a facile self-templated method to fabricate bimetal Transition-metal oxides (TMOs) electrodes for hybrid supercapacitors. [ABSTRACT FROM AUTHOR]