Enhanced electrochemical performance in lithium ion batteries of a hollow spherical lithium-rich cathode material synthesized by a molten salt method

A high voltage layered Li1.2Ni0.16Co0.08Mn0.56O2 cathode material with a hollow spherical structure has been synthesized by molten-salt method in a NaCI flux. Characterization by X-ray diffraction and scanning electron microscopy confirmed its structure and proved that the as-prepared powder is constituted of small, homogenously sized hollow spheres （1-1.5 μm）. The material exhibited enhanced rate capability and high first cycle efficiency due to the good dispersion of secondary particles. Galvanostatic cycling at different temperatures （20, 40, and 60 ℃） and a current rate of 2 C （500 mA.g-1） showed no significant capacity fade.

Stepwise synthesis of cuprous oxide nanoparticles with adjustable structures and growth model

By stepwise adding of reducer N2H4.H2O, cuprous oxide （Cu2O） nanoparticles （NPs） with adjustable structures were synthe- sized. The features of Cu2O NPs were characterized by XRD, TEM and UV-Vis absorption spectra. When the reducer was added into the reactant system at one time, the sizes of the Cu2O NPs are in the range of 120-140 nm. Most Cu2O NPs are sol- id spheres. As the reducer was divided into two equal parts and stepwisely added, almost all the NPs are hollow spheres with good size （150-170 nm） distribution and dispersity. But when the reducer was divided into three or four equal parts and stepwisely added, the NPs are hollow spheres, core-shell structures or solid spheres, and the sizes distribution of the products is deteriorated. The effect of sodium hydrate （NaOH） was also probed. Addition of NaOH speeded up the nucleation and growth processes of Cu2O NPs. With the alkalinity increase, the shells of the hollow spheres become compact and the thicknesses of the shells increase, but the size distribution of the NPs is deteriorated. The absorption spectra of the CuzO NPs are tunable. With the shell thicknesses increase, the absorption peaks have red shifts. An inside-outside growth model of Cu2O NPs was proposed to explain the results. The Cu2O single crystalline grains grow not only in the reactant solution, but also inside of the hollow nanospheres. The new Cu2O nanocrystallines can not only aggregate onto the shells of the nano hollow spheres, but also inside and outside of the hollow spheres, which leads to increasing the shell thicknesses of the hollow spheres, forming core-shell structures or small solid spheres of Cu2O NPs, respectively.