高密度球形纳米β-Ni(OH)_2制备及高倍率充放电研究

Preparation and high rate properties of β-Ni(OH)_2

通过络合沉淀法制备纳米二次结构的球形氢氧化镍粉体。X射线衍射光谱法(XRD)和扫描电子显微镜法(SEM)分析表明产物为纳米氢氧化镍薄片构成的粒径为8～20μm之间的球形β型氢氧化镍。实验发现,样品的结构和密度主要受pH值和氨水浓度的支配,11.0≤pH≤11.7时,氨水浓度对样品密度起着决定性作用。通过调节合适的pH条件,可以控制氢氧化镍薄片的厚度和堆积密度从而使样品的振实密度在1.90～2.10 g/cm3之间可控。恒流充放电测试表明,样品在2 000 mA/g高电流密度下具有良好的快速充放电性能,其放电比容量在高压段高达219～277 mAh/g。

The spherical nickel hydroxide powders with the nano-sized secondary structure were synthesized by controlled complexation precipitation. The analysis of XRD and SEM indicates that the product is spherical G-nickel hydroxide with the size between 8-20 um and it is composed of the nano-sized nickel hydroxide flake, It is found that the structure and density of the sample is mainly affected by pH and the concentration of ammonia solution. It plays a decisive role on the sample density when the pH value iscontroUed between 11.00-11.70. By adjusting the appropriate pH conditions, the thickness of nickel hydroxide flake and piled density can be controlled so that the tap density of the sample is between 1.90 g/cm3 and 2.10 g/cm3, The galanostatic charge-discharge tests show the samples have excellent fast charge and discharge property and the high potential section of the discharge specific capacity is up to 219-277 mAh/g at the current density of 2000 mA/g.