核壳结构Ni(OH)_x(x=2.01～2.15)电极材料的制备及电化学性能

Preparation and Electrochemical Performance of Ni(OH)_x(x=2.01～2.15) Electrode Material with Core/shell Structure

采用化学氧化法制备了碱性二次电池用正极材料Ni(OH)x。采用SEM、TEM、XRD等手段表征了样品的形貌及物相特征,测定了样品的平均氧化态,并考察了其作为镍氢电池正极活性材料的电化学性能。结果表明:经过氧化处理的球形Ni(OH)2表面形成了β-NiOOH,呈现出明显的核壳式结构,制备的样品中Ni的平均氧化态分别为:2.01、2.05、2.13,nNi3+/nNi介于1%～15%之间,以制备的样品为正极材料组装成镍氢模拟电池在0.2C倍率下充放电,样品的放电容量为275±10mAh·g-1;1C充放电条件下,Ni平均氧化态为2.05的样品首次放电容量为268mAh·g-1,270次循环后容量保持率为98%。

The positive active materials Ni（OH）x （x=2.01-2.15） for Ni-based rechargeable alkaline batteries were prepared through a simple route of chemical oxidation. The samples were characterized by XRD, SEM, TEM and TG/ DSC. Average Ni oxidation state （OS） of the sample and the electrochemical performance were investigated, respectively. Results show that a core/shell structure is formed with the β-NiOOH coating outside after the surface modification. OS of the different samples are 2.01, 2.05, 2.13, respectively, with the nNi^3＋/nNi of 1%-15%. The Ni/ MH battery simulators with the above treated samples as positive active material show the discharge capacity of 275±10 mAh.g^-1 under 0.2C charge/discharge rate, a first discharge capacity of 268 mAh.g^-1 with a capacity maintenance of 98% after 270 cycles under 1C charge/discharge rate for the sample with the average Ni OS of 2.05.