化学沉积处理对RE-Mg-Ni系负极材料电化学性能影响

Electrochemical Properties of La-Mg-Ni Based Negative Electrodes through Electroless-Deposition

为了改善RE-Mg-Ni系超晶格负极材料的综合电化学性能,以NaH2PO2作为还原剂,对La0.75Mg0.25Ni3.4Al0.1负极材料进行化学沉积W-PNi/Y3+,对化学沉积的实验条件进行正交实验设计L9(34)。研究了不同化学沉积实验条件下(还原剂浓度、温度和时间)合金电极的电化学性能。扫描电镜及能谱(SEM-EDS)分析表明,包覆处理后,样品表面沉积了球形Y-Ni-W-P共沉积物的颗粒,电化学性能测试表明,与未处理相比,沉积处理后合金电极活化次数、合金电极循环寿命、高倍率放电性能、交换电流密度和极限电流密度率均得到明显的提高。这表明了WNi-P三元共沉积能有效地提高贮氢合金电极电化学性能,处理温度是电极循环寿命和放电容量最为显著的影响因素,在NaH2PO2浓度25 g·L^-1,处理温度80℃,时间30 min时综合电化学性能最佳。

In order to improve overall electrochemical properties of super lattice RE-Mg-Ni based negative materials,the W-P-Ni/Y3+electroless-deposition on the surface of La0.75Mg0.25Ni3.4Al0.1 hydrogen storage alloy particles was prepared using NaH2PO2 as reducing agent.The electrochemical properties of the alloy electrodes of the different condition(concentration of reducing agents,temperature of reaction and time)were investigated by orthogonal experimental design L9(34),the optimum echnique was determined and processing the data with range analysis and variance analysis.Scanning electron microscopy dispersive spectrometer(SEM-EDS)results showed that spherical Y-Ni-W-P sediment particles coated on the alloy.The electrochemical tests showed that the coated hydrogen storage alloy electrodes could lead to significantly increase in the activation number,the cyclic stability,high-rate discharge ability,exchange current density and limiting current density.All of the above indicated that the technique of W-Ni-P coating by chemical plating could effectively improve the electrochemical performance of hydrogen storage alloy electrodes.Processing temperature was the most significant factors of electrode cycle life and discharge capacity.The suitable treatment conditions were:concentration of NaH2PO225 g·L^-1,temperature of reaction 80℃,time 30 min.