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The design of a simple and safe method for constructing heterojunction structures in nanocomposites is a promising strategy for the manufacture of high-performance electrochemical energy storage devices. In this paper, based on the "less-liquid" reaction system and the assistance of the generated NaCl, a heterojunction-containing zero-dimensional (0 D) CoS2/NiS2 nanocomposite with particle sizes ranging from 50 to 200 nm were prepared. During this reaction, the reactant carries crystalline water to provide a liquid environment. Similarly, the lattice occupation of the generated NaCl promotes the construction of a large number of heterogeneous structures inside the nanostructured materials. The prepared material was subsequently employed as a cathode material for the Mg2+/Li+ hybrid battery (MLHB). The interface effect of the heterostructures induces an electric field within the nanocrystals, resulting in a lower ion diffusion resistance, and facilitating interfacial electron transport. Therefore, the heterojunctions accelerated the diffusion dynamics at the interface, and increased the charge-transfer rate. Mg2+ and Li+ exhibit reversible synergistic effects. More specifically, at a current density of 0.2 A g–1, the initial discharge specific capacity was 785.5 mAh g–1, while at a current density of 0.5 A g–1, a discharge specific capacity of 317.54 mAh g–1 was maintained over 200 cycles. And the Coulombic efficiency was maintained at ∼99.8%. This simple and safe design method for nanoscale heterogeneous materials provides a method for developing high-performance MLHB cathode materials. [ABSTRACT FROM AUTHOR]

Rechargeable magnesium batteries (RMBs) are low-cost energy storage devices, but they lack suitable cathode materials. Traditional sulfur (S8) cathodes have attracted much attention because of their high energy density; however, their cycling stability, conductivity, and reversibility are inferior. In this work, porous carbon materials with abundant pores were obtained by graded pore-making and S@C composite materials were obtained as cathodes for magnesium–sulfur batteries after loading porous carbon materials with sulfur. The interconnected pores provide the electrode material with a wealth of electrons and ion transport channels. The hollow structure of the carbon material facilitates the electrode–electrolyte contact area ensuring ion supply at high currents. Magnesium electricity assembled using S@C for the cathode had a high initial discharge specific capacity of 728 mA h g−1 at 50 mA g−1. When the magnification cycle reached 2000 mA g−1, it still had a high discharge-specific capacity of 242 mA h g−1, and the coulombic efficiency reached ∼100%, indicating excellent magnification performance. At a current density of 200 mA g−1, the maximum discharge-specific capacity was 420 mA h g−1. After 100 cycles, a discharge-specific capacity of ∼100 mA h g−1 remained with good cycling stability. This work provides a general strategy for the preparation of porous carbon composites and new insights for high-rate energy storage systems. [ABSTRACT FROM AUTHOR]

Magnesium (Mg)‐ion batteries with low cost and good safety characteristics has attracted a great deal of attention recently. However, the high polarity and the slow diffusion of Mg2+ in the cathode material limit the development of practical Mg cathode materials. In this paper, an anion‐rich electrode material, NiS2, and its composite with Ni‐based carbon nanotubes (NiS2/NCNTs) are explored as the cathode materials for Mg‐ion batteries. These NiS2/NCNTs with excellent Mg2+ storage property is synthesized by a simple in situ growth of NiS2 nanoparticles on NCNTs. NiS2 with both a large regular cavity structure and abundant sulfur‐sulfur (SS) bonds with high electronegativity can provide a large number of active sites and unobstructed transport paths for the insertion–disinsertion of Mg2+. With the aid of 3D NCNTs skeleton as the transport channel of the electron, the NiS2/NCNTs exhibit a high capacity of 244.5 mAh g−1 at 50 mA g−1 and an outstanding rate performance (94.7 mAh g−1 at 1000 mA g−1). It achieves capacitance retention of 58% after 2000 cycles at 200 mA g−1. Through theoretical density functional theory (DFT) calculations and a series of systematic ex situ characterizations, the magnesiation/demagnesiation mechanisms of NiS2 and NiS2/NCNTs and are elucidated for fundamental understanding. [ABSTRACT FROM AUTHOR]

Extreme application environments, such as the exploration of space and living in polar regions, require electrochemical energy storage devices to operate well at ultralow temperatures. Aqueous-based supercapacitors (ASCs) have attracted much attention because of their high safety, high-rate performance, and long cycle-life. However, their application in low-temperature environments is also severely limited by the high freezing point of the aqueous-based electrolyte. In this paper, based on the ability of the coordination between Ni2+ and Cl− to restrict the longitudinal growth of Ni(OH)2 along the (0 0 1) crystal plane and the inherent ultralow freezing point of NaCl aqueous solution, cost efficient NaCl was explored for its ability to both regulate the preparation of one-dimensional (1D) Ni(OH)2 nanorods and develop a two-solute electrolyte for ASCs with ultralow-temperature resistance. The 1D Ni(OH)2 nanorods comprised bundles of finer nanorods with a diameter of about 16 nm, which could authentically shorten the transport distance of OH− and electrons, providing enough deformation space for them to interact with each other. Both the three-electrode system and assembled ASCs using this electrode material of 1D Ni(OH)2 nanorods were used to test the specific capacitances, and it was found that this material could give 1.6 times higher values than those of 2D Ni(OH)2 nanosheets at the corresponding scan rates or current densities. Further, the capacitance retention was found to gradually increase from 84.04% for NO0//AC to 96.24% for NO16//AC after 10 000 cycles at 5 A g−1. With the assistance of the two-solute electrolyte, the capacitance retention of NO16//AC at −30 °C was up to 61.1% from 0.5 to 10 A g−1, and 90.21% after 10 000 cycles at 5 A g−1. These results demonstrate not only the potential application of low-cost NaCl in energy storage systems, but also the application of ASCs in ultralow-temperature environments. [ABSTRACT FROM AUTHOR]

Ni1/3Co2/3(CO3)1/2(OH)·0.11H2O (NCC) was in situ constructed on the surface of CNTs, which realized the nanoscale recombination of NCC and CNTs. The as-obtained CNTs@NCC composite showed excellent electrochemical performance in both aqueous and all-solid-state electrolyte systems owing to the improvement in the utilization of active materials. This work provides a general duty strategy for improving the combined electrochemical performance of electrode materials for energy storage. [ABSTRACT FROM AUTHOR]

Selection of the friction electrode materials is crucial to the performance of a triboelectric nanogenerator (TENG). In the present study, a metal–organic coordination complex containing organosulfonate counteranions with electron‐donating ability was synthesized through the coordination‐driven self‐assembly approach under mild reaction conditions and was chosen as a positive electrode material to construct a triboelectric nanogenerator, exhibiting high‐output performance with a peak value of short circuit current density of 98.6 μA and an output voltage of 1180 V. As a practical application, it was shown to light up 1488 commercial green LEDs and power an anticorrosion system device to protect metals from corrosion. [ABSTRACT FROM AUTHOR]

Porous and carbon composited binary transition metal oxide nanomaterials provide high ionic conductivity and electronic conductivity. However, it still remains a challenge to use a simple method to achieve in situ both composite and porous one-dimensional (1D) nanorods. In this paper, we have prepared porous NiMoO4/C (NMO/C) composite nanorods using a solvothermal method and subsequent annealing step. In the solvothermal reaction, a simple organic solvent, cyclohexane, was introduced as a carbon source and pore-forming agent, realizing the controllable synthesis of porous 1D nanorods composited with heteroatoms via a simple strategy. This structure shows improved ionic and electronic conductivities and provides a large number of electrochemical reaction active sites, making it a possible candidate to be used as a high capacity electrode material for supercapacitors. On this basis, electrode materials with higher rate performance and utilization were prepared by mixing NMO/C with carbon nanotubes (CNTs) through simple physical mixing. Due to the 1D electrochemical synergistic effects of NMO/C and CNTs, the assembled NMO/C-CNT electrode shows a specific capacity of 325.1 F g−1 (at a current density of 0.5 A g−1) in a two-electrode system. At a high current density of 8 A g−1, the specific capacity is still 182 F g−1. This report provides a new strategy for the designed in situ synthesis of porous composite nanorods. [ABSTRACT FROM AUTHOR]

Herein, we have realized the transformation from Cu2S to CuS phase by a facile secondary vulcanization. The CuS completely inherited the special morphology of the precursor nanocrystal, and the feature excludes the structural and dimensional influence in the study of the effects of Cu(I) and Cu(II) on photocatalytic properties. Under visible light irradiation, the photocatalytic performances of Cu2S@CT (CT, biomass carbon tube) and CuS@CT composites were examined on organic dye (methylene blue, MB) degradation and Cr (VI) reduction at different original solution pH. Both photocatalysts exhibit good photocatalytic activity under favourable conditions, which should be attributed to the high specific surface area and luxuriant active sites of the materials with special nanostructures. Moreover, the Cu2S@CT and CuS@CT show distinct‐different oxidability and reducibility due to the compositional difference, Cu2S@CT composites have better reduction properties of Cr(VI) at pH=2, while the CuS@CT composites exhibit better degradation activity of MB at pH=10. [ABSTRACT FROM AUTHOR]