NiS2 nanoparticles anchored on open carbon nanohelmets as an advanced anode for lithium-ion batteries

A NiS2/C composite as an innovative anode material for sodium-ion batteries: ex situ XANES and EXAFS studies to investigate the sodium storage mechanism

The successful deployment of sodium-ion batteries (SIBs) requires high-performance sustainable and cost-effective anode materials having a high current density. In this regard, sodium disulphide (NiS2) has been prepared as a composite with activated carbon (C) using a facile hydrothermal synthesis route in the past. The X-ray diffraction pattern of the as-prepared NiS2/C composite material shows well-defined diffraction peaks of NiS2. Most carbonaceous materials are amorphous, and the Brunauer-Emmett-Teller (BET) study shows that the surface area is close to 148 m2 g-1. At a current density of 50 mA g-1, the NiS2/C composite exhibits a high capacity of 480 mA h g-1 during the initial cycle, which subsequently decreases to 333 mA h g-1 after the completion of the 100th cycle. The NiS2/C composite electrode provides an exceptional rate capability by delivering a capacity of 270 mA h g-1 at a high current density of 2000 mA g-1, suggesting the suitability of the NiS2/C composite for SIBs. Ex situ X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) analyses at the Ni K-edge have been used to examine the type of chemical bonding present in the anode and also how it changes during electrochemical redox cycling. The understanding of the sodium storage mechanism is improved by the favorable results, which also offer insights for developing high-performance electrode materials for rechargeable SIBs.

Flower-Like NiS2 /WS2 Heterojunction as Polysulfide/sulfide Bidirectional Catalytic Layer for High-Performance Lithium-Sulfur Batteries

The slow sulfur oxidation-reduction kinetics are one of the key factors hindering the widespread use of lithium-sulfur batteries (LSBs). Herein, flower-shaped NiS₂ -WS₂ heterojunction as the functional intercalation of LSBs is successfully prepared, and effectively improved the reaction kinetics of sulfur. Flower-like nanospheres composed of ultra-thin nanosheets (≤10 nm) enhance quickly transfer of mass and charge. Meanwhile, the heterostructures simultaneously serve as an electron receptor and a donor, thereby simultaneously accelerating the bidirectional catalytic activity of reduction and oxidation reactions in the LSBs. In addition, the adsorption experiment, chemical state analysis of elements before and after the reaction and theoretical calculation have effectively verified that NiS₂ -WS₂ heterojunction nanospheres optimize the adsorption capacity and bidirectional catalytic effect of polysulfides. The results show that the initial discharge capacity of NiS₂ -WS₂ functional intercalation is as high as 1518.7 mAh g^-1 at 0.2 C. Even at a high current density of 5 C, it still shows a discharge specific capacity of 615.7 mAh g^-1 , showing excellent rate performance. More importantly, the capacity is 258.9 mAh g^-1 after 1500 cycles at 5 C, and the attenuation per cycle is only 0.039%, and the Coulomb efficiency remains above 95%.

Facile Route to Achieve Self-Supported Cu(OH)2/Ni3S2 Composite Electrode on Copper Foam for Enhanced Capacitive Energy Storage Performance

Herein, a Cu(OH)2/Ni3S2 composite was successfully prepared through facile two-step electrodeposition. As the electrode substrate and the only copper source, the copper foam underwent surface oxidation by galvanostatic deposition technology to form Cu(OH)2, and the subsequent coverage of Ni3S2 was achieved by potentiostatic deposition. The Cu(OH)2 acts as a skeleton, providing support for Ni3S2 growth, thus providing more abundant electrochemical active sites. By virtue of the in situ growth strategy and the synergy of different components, the optimized Cu(OH)2/Ni3S2 electrode illustrates significantly enhanced pseudocapacitance performance, with an areal specific capacitance of 11.43 F cm−2 at 2 mA cm−2, good coulombic efficiency of 94.55%, and remarkable cyclic stability (83.33% capacitance retention after 5000 cycles).

Rationally integrated nickel sulfides for lithium storage: S/N co-doped carbon encapsulated NiS/Cu2S with greatly enhanced kinetic property and structural stability

Nickel sulfides are promising anode materials for lithium-ion batteries (LIBs) due to their high theoretical capacities but suffer from the sluggish kinetic process and poor structural stability. Herein, we develop...

Highly uniform platanus fruit-like CuCo2S4 microspheres as an electrode material for high performance lithium-ion batteries and supercapacitors

Platanus fruit-like CuCo₂S₄ microspheres were fabricated by using a facile hydrothermal method followed by a sulfidation process. As a lithium storage material, they deliver an outstanding initial specific capacity of 1119.3 mA h g^-1 at 0.05 A g^-1 and a high reversibility of 954 mA h g^-1 over 200 cycles even at 1 A g^-1. In addition, when applied in supercapacitors they display a superb specific capacitance of 824 F g^-1 at 1 A g^-1, even over 10 000 cycles and they can also maintain 75% retention at 5 A g^-1 and exhibit good reversibility. Furthermore, an advanced asymmetric supercapacitor (ASC) exhibits an advantageous energy density of 36.67 W h kg^-1 when the power density increases up to 750 W kg^-1. Additionally, the assembled device can easily light a 1.5 V bulb for several minutes. The excellent performance of CuCo₂S₄ is due to the bimetallic synergistic effect and the unique platanus fruit-like microsphere architecture, which can limit the restacking of the structure and provide suitable voids. This excellent performance confirms that platanus fruit-like CuCo₂S₄ microspheres are a promising electrode material for energy storge. This work will provide a new strategy to prepare high-performance bimetallic sulfide anode materials by a facile method.