新能源汽车电极材料的制备与电化学性能研究

Preparation and Electrochemical Properties of Electrode Materials Used for New Energy Vehicles

采用中频感应熔炼和退火工艺制备了La_(0.74)Mg_(0.26)Ni_(3.59)电极材料,研究了退火保温时间对电极材料物相组成、显微形貌和电化学性能的影响。结果表明,铸态和950℃/12 h退火态电极材料的主要物相为CaCu_5型LaNi_5相、3R-Ce_5Co_(19)型(LaMg)_5Ni_(19)相、3R-Gd_2Co_7型(LaMg)_2Ni_7相和2H-Ce_2Ni_7型(LaMg)_2Ni_7相。随着退火时间的延长,电极材料中的物相有由2H和3R型相结构朝着3R型相结构转变的特征;退火态La_(0.74)Mg_(0.26)Ni_(3.59)电极材料的最大放电容量、100周吸/放氢循环后电化学容量和100周吸/放氢循环后循环寿命都要大于铸态试样,退火处理后La_(0.74)Mg_(0.26)Ni_(3.59)电极材料的耐腐蚀性能得到明显提高。这主要与La_(0.74)Mg_(0.26)Ni_(3.59)电极材料中3R-Ce_5Co_(19)型(LaMg)_5Ni_(19)相和3R-Gd_2Co_7型(LaMg)_2Ni_7相的放电容量和结构匹配性高于Ca Cu_5型LaNi_5相有关。

La0.74 Mg0.26Ni3.59electrode materials were prepared by means of medium frequency induction melting and anneal ing process, the effects of annealing time on phase composition, electrode material microstructure and electrochemical properties of electrode materials were studied. The results show that, the main phases of as cast and 950 ℃/12 h annealed electrode materials are CaCu5 type LaNi5 phase, 3R-CesCo19 type （LaMg）sNil9 phase, 3R-Gd2C07 type （LaMg）2Ni7 phase and 2H-Ce2Ni7 type （LaMg）2Ni7 phase, with the annealing time increasing, the phase in the electrode material is characterized by the phase transition of the 2H and 3R phase structures toward the 3R type. The maximum discharge capacity, electrochemical capacity after 100 cycles of hydrogen absorption and desorption cycles, cycle life after 100 cycles of hydrogen-absorption and desorption of the annealed La0.74 Mg0.26Ni3.59 electrode material are greater than those of the as cast sample, and after annealing treatment, the corrosion resistance ofLa0.74 Mg0.26Ni3.59 electrode material obviously improves, which are mainly related to the discharge capacity and structure matching of 3R-Ce5Co19 type （LaMg）5Ni19 phase and 3R-Gd2Co7 type （LaMg）2Ni7 phase in La0.74 Mg0.26Ni3.59 electrode materials are higher than that of CaCu5 type LaNi5 phase.