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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CaCu_5型LaNi_5相有关。
The La_ (0.74) Mg_ (0.26) Ni_ (3.59) electrode material was prepared by IF induction melting and annealing process. The effects of annealing time on the phase composition, morphology and electrochemical properties of the electrode material were studied. The results show that the main phases of as-cast and 950 ℃ / 12 h annealed electrode materials are CaCu_5 LaNi_5 phase, 3R-Ce_5Co_ (19) LaMg_5Ni_ (19) phase and 3R-Gd_2Co_7 LaMg_2Ni_7 phase And 2H-Ce_2Ni_7 type (LaMg) _2Ni_7 phase. With the extension of annealing time, the phase of the electrode material changed from 2H and 3R toward the 3R phase structure. The maximum discharge of the annealed La_ (0.74) Mg_ (0.26) Ni_ (3.59) The capacity, the electrochemical capacity after 100 cycles of absorption / desorption cycles, and the cycle life after 100 cycles of absorption / desorption cycle are all larger than that of the as-cast samples. After annealing treatment, the La_ (0.74) Mg_ (0.26) Ni_ (3.59) Corrosion resistance has been significantly improved. This is mainly related to the discharge capacity and structural compatibility of 3R-Ce 5 Co 19 type LaMg 5 Ni 19 phase and 3R-Gd 2 Co 7 LaMg 2 Ni 7 phase in La 0.74 Mg 0.26 Ni 3.59 electrode material. Higher than CaCu_5 type LaNi_5 phase.