Hierarchical architectured NiS@SiO2 nanoparticles enveloped in graphene sheets as anode material for lithium ion batteries

Catalytic chemistry inspired hollow carbon nanofibers loaded with NiS/Ni as high-performance and safe Li+ reservoir

Transition metal sulfides (TMSs) based anodes hold a very broad application prospect in lithium ion batteries (LIBs). In this work, the catalytic effect of metallic nickel at high temperature was used to generate hollow carbon nanofibers loaded with NiS and Ni (denoted as NiS/Ni@HCNF). The heteroatoms doped carbon fibers buffer the huge volumetric change of NiS during the discharge/charge process, and enhance the ion transport efficiency and electrical conductivity. In addition, the high specific surface area brought by the hollow carbon nanofibers can accelerate the electrolyte penetration and speed up the transport of ions as well as electrons. When used as anode of half cell, this electrode gives 958.5 and 612.9 mAh/g after running 1000 cycles under 1 and 2 A/g, showing the extremely-low attenuation rates of 0.0483 % per cycle and 0.0643 % per cycle, respectively. Impressively, NCM//NiS/Ni@HCNF battery shows the discharge capacity of 187.6 mAh/g at 1st cycle. Regarding the next 100 cycles, the relatively-high discharge capacities (>110 mAh/g) and coulombic efficiency (CE) values (>96 %) are discerned. It is noted that the usage of NiS/Ni@HCNF electrode improves the activation energy for thermal runaway, corroborating the elevated thermal safety of battery.

ZnS/SnS2 Heterostructures Encapsulated in N-Doped Carbon Nanofibers for High-Performance Alkali Metal-Ion Batteries

Heterogeneous composite ZnS/SnS2 is designed to meet various requirements for alkali metal-ion batteries. The composite is prepared using an electrostatic spinning method and encapsulated in N-doped carbon fibers after high-temperature vulcanization. The special structure of the composite provides a dependable interconnection and fast conductive network for alkali metal ions. The conductive carbon network shortens the diffusion path and greatly improves the migration efficiency of the alkali metal ions in the electrode. As expected, when the current density is 0.1 A g-1, the ZnS/SnS2@NCNFs maintain a high discharge capacity of more than 1437.5, 1321.2, and 861.6 mA h g-1 for lithium-ion, sodium-ion, and potassium-ion batteries, respectively. What is more, a full cell using a prelithiated composite anode and a LiFePO4 cathode is tested and shows excellent electrochemical performance. This work provides new perspectives for the development of novel anodes that can efficiently store alkali metal ions, as well as for the fine-structure design of materials.

SnCo Nanoparticles Loaded in Hollow Carbon Spheres Interlinked by N-Doped Carbon Fibers for High-Performance Sodium-Ion Batteries

The development of Sn-based materials with electrochemically inactive matrices is a novel strategy to alleviate the volume expansion and giant structure strain/stress during the sodiation/desodiation process. In this work, a freestanding membrane based on the unique bean pod-like host composed by nitrogen-doped carbon fibers and hollow carbon spheres (HCSs) encapsulated with SnCo nanoparticles is synthesized by electrospinning (B-SnCo/NCFs). In this unique bean pod-like structure, Sn acts as a host for Na⁺ storage, while the Co plays the important role of an electrochemically inactive matrix that can not only buffer the volume variations but also inhibit aggregation and particle growth of the Sn phase during the electrochemical Na-Sn alloying process. Meanwhile, the introduction of hollow carbon spheres can not only provide enough sufficient void space to withstand the volume expansion during the (de)sodiation processes but also improve the conductivity of the anode along the carbon fibers. Furthermore, the B-SnCo/NCF freestanding membrane can increase the contact area between the active material and the electrolyte, which can provide more active sites during the cycling process. When used as an anode material for Na-ion batteries, the freestanding B-SnCo/NCF anode exhibits an outstanding rate capacity of 243.5 mA h g^-1 at 1.6 A g^-1and an excellent specific capacity of 351 mA h g^-1 at 0.1 A g^-1 for 300 cycles.

Engineering hierarchically ZnS/NiS/NiS2 hollow porous urchin-like composite towards exceptional lithium storage

Complex hollow structure nanostructure is regarded as the desired approach to alleviating the volume change of lithium-ion batteries (LIBs). In this work, ZnS/NiS/NiS₂ composite with a distinctive hierarchical hollow porous urchin-like structure was prepared through pyrolysis of bimetal-organic frameworks obtained by one-step solvothermal and firstly used as anodes for LIBs. Varying the metal molar ratios allows the control of the surface area and pore size distribution of ZnS/NiS/NiS₂. The obtained composite with a hollow porous urchin-like structure exhibits high porosity, large specific surface area, and strong synergetic interaction between ZnS and NiS/NiS₂ can greatly buffer the volume expansion to keep the mechanical stability, ensure sufficient contact region between electrolyte and electrodes and shorten the Li⁺ transfer distance, meanwhile, the carbon derived from organic ligand of bimetal-organic frameworks also constructs the conductive matrix to accelerate electrons transfer. Based on the above outstanding properties, the obtained material delivers excellent rate capacity, superior reversible capacity, and long-cycle stability, especially disclosing a capacity of 615 mAh·g^-1 after 300 cycles at 2 A·g^-1. This work proposes a feasible strategy to obtain a unique hollow porous urchin-like structure through pyrolysis of bimetal organic frameworks, it can be extended to fabricate other mixed metal sulfides nanostructures with excellent electrochemical performances.

Carbon Yarn-Ball-Entangled SiO2 Anode with Excellent Electrochemical Performance for Lithium-Ion Batteries

Various nanoscale SiO₂ and their composites have demonstrated superior electrochemical performance as anodes for lithium-ion batteries. However, both the battery production and real applications require the integration of nanoscale SiO₂ into micrometer-sized secondary particles while preserving their excellent stability and conductivity, which remains a great challenge. In this work, a unique carbon yarn-ball structure is successfully synthesized that entangles nanoscale SiO₂ together to build a micrometer-sized secondary particle. The hook-like carbon wires closely adhere to individual SiO₂ nanoparticles, which constitute the basic unit of the yarn-ball structure. The entangled carbon wires create a network of electron conduction highways for SiO₂ , and the yarn-ball structure provides a resilient 3D matrix that can effectively buffer the anisotropic volume changes of SiO₂ during Li ion insertion/extraction. Under 0.1 A g^-1 , the carbon yarn-ball-entangled SiO₂ can deliver a 1297 mAh g^-1 discharge capacity with a small irreversible capacity of 82 mAh g^-1 . The entangled carbon yarn ball firmly maintains its structural integrity during high-rate cycling (1 A g^-1 ), which gives rise to a large accessible capacity (709 mAh g^-1 , 90.7% retention for 500 cycles), superior coulombic efficiency (>99.9%), and excellent structural stability.

Few-Layer MoS2 Nanosheets Encapsulated in N-Doped Carbon Hollow Spheres as Long-Life Anode Materials for Lithium-Ion Batteries

Two-dimensional molybdenum disulfide (MoS₂ ) has been recognized as a promising anode material for lithium-ion batteries (LIBs) due to its high theoretical capacity, but its rapid capacity decay owing to poor conductivity, structure pulverization, and polysulfide dissolution presents significant challenges in practical applications. Herein, triple-layered hollow spheres in which MoS₂ nanosheets are fully encapsulated between inner carbon and outer nitrogen-doped carbon (NC) were fabricated. Such an architecture provides high conductivity and efficient lithium-ion transfer. Moreover, the NC shell prevents aggregation and exfoliation of MoS₂ nanosheets and thus maintains the integrity of the nanostructure during the charge/discharge process. As anode materials for LIBs, the C@MoS₂ @NC hollow spheres deliver a high reversible capacity (747 mA h g^-1 after 100 cycles at 100 mA g^-1 ) and excellent long-cycle performance (650 mA h g^-1 after 1000 cycles at 1.0 A g^-1 ), which confirm its potential for high-performance LIBs.

Hydrous nickel sulphide nanoparticle decorated 3D graphene foam electrodes for enhanced supercapacitive performance of an asymmetric device

Hydrous nickel sulphide is successfully synthesized on graphene foam (Ni₉S₈/GF) using a facile chemical bath deposition (CBD) method for supercapacitor application.

Synthesis of nickel and cobalt sulfide nanoparticles using a low cost sonochemical method

Nickel and cobalt sulfides are promising materials in different cutting-edge research areas like solar cells, supercapacitors, catalysts, and electrode materials. Nickel and cobalt sulfides with various stoichiometries have been synthesized sonochemically from Ni(CH₃COO)₂ ∙ 4H₂O, Co(CH₃COO)₂ ∙ 2H₂O and different sulfur precursors using a direct immersion ultrasonic probe. The products were characterized by X-ray powder diffraction, transmission electron microscopy (TEM) including EDX analysis, IR and UV-Vis spectroscopy and elemental analysis. Following products have been obtained: NiS, Ni₃S₄, CoS_1.097 and Co₉S₈, with average crystallite sizes in the range 7-30 nm. Effects of different reaction conditions on the size, morphology and optical band-gap energy were evaluated. Optical band-gap energies in the range 3.3 eV-3.8 eV were observed for the obtained nanoparticles.

Al2O3coated metal sulfides: one-pot synthesis and enhanced lithium storage stability via localized in situ conversion reactions

Al₂O₃coated Ni₃S₄nanoparticles have been designed to promote thein situconversion of Ni₃S₄, by confining the formed polysulfides within the Al₂O₃layer; these nanoparticles exhibit a high reversible capacity of 651.6 mA h g⁻¹at 500 mA g⁻¹, even after 400 cycles.

Flexible and high capacity lithium-ion battery anode based on a carbon nanotube/electrodeposited nickel sulfide paper-like composite

A flexible NS@CNT composite is synthesized by electrodeposition, showing a record specific capacity in terms of the entire electrode mass.

In Situ Synthesis of MnS Hollow Microspheres on Reduced Graphene Oxide Sheets as High-Capacity and Long-Life Anodes for Li- and Na-Ion Batteries

Uniform MnS hollow microspheres in situ crystallized on reduced graphene oxide (RGO) nanosheets via a facile hydrothermal method. The MnS/RGO composite material was used as the anode for Na-ion batteries for the first time and exhibited excellent cycling performance, superior specific capacity, and great cycle stability and rate capability for both Li- and Na-ion batteries. Compared with nonencapsulated pure MnS hollow microspheres, these MnS/RGO nanocomposites demonstrated excellent charge-discharge stability and long cycle life. Li-ion storage testing revealed that these MnS/RGO nanocomposites deliver high discharge-charge capacities of 640 mAh g(-1) at 1.0 A g(-1) after 400 cycles and 830 mAh g(-1) at 0.5 A g(-1) after 100 cycles. The MnS/RGO nanocomposites even retained a specific capacity of 308 mAh g(-1) at a current density of 0.1 A g(-1) after 125 cycles as the anode for Na-ion batteries. The outstanding electrochemical performance of the MnS/RGO composite attributed to the RGO nanosheets greatly improved the electronic conductivity and efficiently mitigated the stupendous volume expansion during the progress of charge and discharge.