Rational design and synthesis of advanced anode materials are extremely important for high-performance lithium-ion and sodium-ion batteries. Herein, a simple one-step hydrothermal method is developed for fabrication of N-C@MoS₂ microspheres with the help of polyurethane as carbon and nitrogen sources. The MoS₂ microspheres are composed of MoS₂ nanoflakes, which are wrapped by an N-doped carbon layer. Owing to its unique structural features, the N-C@MoS₂ microspheres exhibit greatly enhanced lithium- and sodium-storage performances including a high specific capacity, high rate capability, and excellent capacity retention. Additionally, the developed polyurethane-assisted hydrothermal method could be useful for the construction of many other high-capacity metal oxide/sulfide composite electrode materials for energy storage.

A monophase nickel phosphide/carbon (Ni₅P₄/C) composite with a thin carbon shell is controllably synthesized via the two-step strategy of a wet-chemistry reaction and a solid-state reaction. In this fabrication, the further diffusion of phosphorus atoms in the carbon shell during the solid-state reaction can be responsible for a chemical transformation from a binary phase of Ni₅P₄-Ni₂P to monophase Ni₅P₄. Galvanostatic charge-discharge measurements indicate that the Ni₅P₄/C composite exhibits a superior, high rate capacibility and good cycling stability. About 76.6% of the second capacity (644.1 mA h g⁻¹) can be retained after 50 cycles at a 0.1 C rate. At a high rate of 3 C, the specific capacity of Ni₅P₄/C is still as high as 357.1 mA h g⁻¹. Importantly, the amorphous carbon shell can enhance the conductivity of the composite and suppress the aggregation of the active particles, leading to their structure stability and reversibility during cycling. As is confirmed from X-ray-diffraction analysis, no evident microstructural changes occur upon cycling. These results reveal that highly crystalline Ni₅P₄/C is one of the most promising anode materials for lithium-ion batteries.

Single-crystalline Ni₂P nanotubes (NTs) were facilely synthesized by using a Ni nanowire template. The mechanism for the formation of the tubular structures was related to the nanoscale Kirkendall effect. These NTs exhibited a core/shell structure with an amorphous carbon layer that was grown in situ by employing oleylamine as a capping agent. Galvanostatic charge/discharge measurements indicated that these Ni₂P/C NTs exhibited superior high-rate capability and good cycling stability. There was still about 310 mAh g⁻¹ retained after 100 cycles at a rate of 5 C. Importantly, the tubular nanostructures and the single-crystalline nature of the Ni₂P NTs were also preserved after prolonged cycling at a relatively high rate. These improvements were attributed to the stable nanotubular structure of Ni₂P and the carbon shell, which enhanced the conductivity of Ni₂P, suppressed the aggregation of active particles, and increased the electrode stability during cycling.

We report the preparation of a nickel-foam-supported graphene sheet/porous NiO hybrid film by the combination of electrophoretic deposition and chemical-bath deposition. The obtained graphene-sheet film of about 19 layers was used as the nanoscale substrate for the formation of a highly porous NiO film made up of interconnected NiO flakes with a thickness of 10–20 nm. The graphene sheet/porous NiO hybrid film exhibits excellent pseudocapacitive behavior with pseudocapacitances of 400 and 324 F g⁻¹ at 2 and 40 A g⁻¹, respectively, which is higher than those of the porous NiO film (279 and 188 F g⁻¹ at 2 and 40 A g⁻¹). The enhancement of the pseudocapacitive properties is due to reinforcement of the electrochemical activity of the graphene-sheet film.

Pure amorphous-carbon (a-C) and C/Ti multilayer films are prepared by pulsed-laser deposition. For each fluence (7 or 10 J cm⁻²), a-C films are deposited with two durations (35 and 120 min) to vary the thickness. The thin films have an sp³ bond ratio and hardness dependant on the fluence. The as-deposited, thick a-C films delaminate and provide a more-nanosized graphitic microstructure, and a lower sp³ bond ratio and hardness compared to thin a-C films, correlating with stress relaxation of the films. The C/Ti multilayer films can be deposited at large thicknesses due to the low internal stress, while the sp³ bond ratio and the hardness increase with decreasing thickness of the Ti bilayer.