Peigen Zhang

The effect of dispersing agent on the formation of aluminium nitride nanoparticles/whiskers

The effect of the amount of dispersing agent on the formation of aluminium nitride (AlN) nanoparticles/whiskers is presented. Various levels of the dispersant [rice bran (RB)] concentration, mass ratio of Al/RB ranging from 0.43 (30:70) to 2.33 (70:30), were systematically investigated. After the heat treatment in a nitrogen atmosphere, all samples with different RB contents could be transformed to AlN nanoparticles and nanowhiskers with trace graphite. In this experiment, the dispersant concentration in the starting mixture not only affects the morphologies of the resultant AlN (particles/whiskers) but also makes the morphology of the AlN whiskers evolve. The mechanisms for the formation and the evolution of AlN whiskers are discussed.

Fabrication of Lithiophilic Copper Foam with Interfacial Modulation toward High-Rate Lithium Metal Anodes

Although metallic lithium is regarded as an ideal anode material for high-energy-density batteries, the low cycling efficiency and safety issues hinder its practical application. In this study, a three-dimensional (3D) lithium composite anode was developed through infusing molten lithium inside the Cu foam anchored by ZnO nanoparticles. The introduced ZnO layer provides the driving force for infusion, leading to the spontaneous wetting of molten lithium. Benefiting from well-confined preloaded lithium in the Cu network, the anode displays ultralow internal resistance and stabilized interface. The fabricated anode for the symmetric cell shows extraordinarily low overpotential at high current densities (15, 33, and 50 mV at 3, 5, and 8 mA cm-2 after 100 cycles, respectively). When paired with Li4Ti5O12 electrode, the half-type cell demonstrates superior rate capability and long-term cycling stability after 1000 cycles at an ultrahigh rate of 10C. To the best of our knowledge, this anode shows the lowest overpotential and the highest rate capacity ever reported for 3D design anodes, confirming their great potential as lithium metal anodes.

Preparation and properties of thermal insulation coatings with a sodium stearate-modified shell powder as a filler

Waste shell stacking with odor and toxicity is a serious hazard to our living environment. To make effective use of the natural resources, the shell powder was applied as a filler of outdoor thermal insulation coatings. Sodium stearate (SS) was used to modify the properties of shell powder to reduce its agglomeration and to increase its compatibility with the emulsion. The oil absorption rate and the spectrum reflectance of the shell powder show that the optimized content of SS as a modifier is 1.5wt%. The total spectrum reflectance of the coating made with the shell powder that is modified at this optimum SS content is 9.33% higher than that without any modification. At the optimum SS content of 1.5wt%, the thermal insulation of the coatings is improved by 1.0°C for the cement mortar board and 1.6°C for the steel plate, respectively. The scouring resistance of the coating with the 1.5wt% SS-modified shell powder is three times that of the coating without modification.

Toward advanced sodium-ion batteries: a wheel-inspired yolk–shell design for large-volume-change anode materials

Yolk–shell structures have found great potential in addressing the huge volume change of alloy-type anodes for lithium-/sodium-ion batteries (LIBs/SIBs). The main challenges associated with yolk–shell structures are the sluggish electron/ion transfer at the yolk–shell interface caused by the point-to-point contact between the yolk and the shell, and the rupture of self-supporting carbon shells during a long-term cycle. Here, inspired by the structure of a wheel, we designed and fabricated a novel yolk–shell structure with a multipoint contact between the yolk and the shell (wheel–shell structure) through a general and scalable approach. The multipoint contact is achieved by bridging SnO2 yolks and graphene shells using carbon nanoribbons, which allows a high-efficiency transfer of electrons and ions inside/outside the wheel–shell structure. Moreover, the interconnected graphene shells function not only as an electrical highway so that all active materials are electrochemically active, but also as a mechanical backbone to maintain the structural integrity. As an anode for SIBs, the wheel–shell structure exhibits extraordinary rate capability (153.3 mA h g−1 at 10.0 A g−1) and robust cycling stability (248.2 mA h g−1 remaining after 1000 cycles at 1.0 A g−1 with a capacity retention of 86.9%). These results demonstrate the most efficient SnO2-based anode ever reported for SIBs. More importantly, the proposed strategy opens up new avenues to boost the electrochemical performance of large-volume-change anode materials for advanced battery systems.

Microstructure and properties of Ag–Ti3SiC2 contact materials prepared by pressureless sintering

Ti3SiC2-reinforced Ag-matrix composites are expected to serve as electrical contacts. In this study, the wettability of Ag on a Ti3SiC2 substrate was measured by the sessile drop method. The Ag–Ti3SiC2 composites were prepared from Ag and Ti3SiC2 powder mixtures by pressureless sintering. The effects of compacting pressure (100–800 MPa), sintering temperature (850–950°C), and soaking time (0.5–2 h) on the microstructure and properties of the Ag–Ti3SiC2 composites were investigated. The experimental results indicated that Ti3SiC2 particulates were uniformly distributed in the Ag matrix, without reactions at the interfaces between the two phases. The prepared Ag–10wt%Ti3SiC2 had a relative density of 95% and an electrical resistivity of 2.76 × 10-3 mΩ·cm when compacted at 800 MPa and sintered at 950°C for 1 h. The incorporation of Ti3SiC2 into Ag was found to improve its hardness without substantially compromising its electrical conductivity; this behavior was attributed to the combination of ceramic and metallic properties of the Ti3SiC2 reinforcement, suggesting its potential application in electrical contacts.