凯发

1.Sodium-ion batteries (SIBs) have attracted great interest as a promising substitute for lithium ion batteries (LIBs) owing to the earth-abundant and cheap sodium resource.[1] Unfortunately, current SIBs usually exhibit slower reaction kinetics, low specific capacity and poor cycle life due to the larger ionic radius of Na+ than that of Li+.[2] Hence, many efforts have been made to explore novel electrode materials with higher discharge/charge capacities. Among various candidates, molybdenum disulfide (MoS2) has been regarded as a promising sodium storage material due to its sandwich-like layered structure and high theoretic capacity (670 mAh g-1).[3] Nevertheless, the relatively low electronic conductivity and serious inherent volume change of MoS2 during sodiation/desodiation lead to low specific capacity and poor cycling stability, which restrict its potential practical application. [4] To solve these challenging problems, we demonstrate a simple glucose carbonization process for preparing foam-like porous carbon sheets-encapsulated MoS2/C nanospheres (MoS2/C⊂pCS) composite. The synergistic effects between the carbon coated MoS2 nanospheres and supporting porous carbon sheets, can not only facilitate the diffusion of Na+ and electrolyte into the electrodes, but also minimize the influence of pulverization and aggregation of MoS2 nanospheres upon prolonged discharge/charge cycling.  As expected, the MoS2/C⊂pCS composite shows high reversible capacity and fast rate capability, as well as long cycle life as an anode material. Such excellent performance demonstrates of the MoS2/C⊂pCS composite make it a promising anode material for advanced SIBs.

2.In this work, a kind of graphene doped spherical mono-disperse silver powder with controllable size and high tap density was synthesized by chemical reduction using silver nitrate as metal source, hydrazine hydrate as reducing agent. The result of SEM images indicated that different size spherical mono-disperse silver particles were obtained. The graphene doped silver paste shows appropriate viscosity (270–370 pas), high thixotropic index (6.50), and good printability when the percentage of organic medium is about 12.00wt.%. Using this silver paste, the front electrode grid of Si solar cells has high ratio of height to width as well as fine edge definition. Meanwhile, the Eff of monocrystalline Si solar cells reach 18.68%.