LaCo_(13-x)Ni_x的结构及其电化学性能

Structure and electrochemical properties of

对LaCo13-xNix（0≤x≤6）化合物的晶体结构与充放电性能进行研究,实验发现:当x≤2时,样品主要由LaCo13型化合物构成,热处理对1:13相化合物的形成有非常重要的影响。电化学实验结果表明LaCo13-xNix（0≤x≤2）化合物的电化学容量随温度的增加而增加;当x≤0.8时,化合物的电化学容量随Ni含量的增加而增加;当x>0.8时,化合物的电化学容量基本不随Ni含量的增加而改变。在70℃和60mA/g充放电电流条件下,我们得到了在该成分范围0.8≤x≤2内的最高电化学容量为359mAh/g,该电化学容量被认为与LaNi5型化合物一样来自于氢原子的吸入与放出。LaCo13-xNix化合物的不足之处是:它们的室温电化学容量较低,和由于Co在KOH溶液中的溶解造成的循环寿命较差。并且Co在KOH中溶解的量随温度的增加而增加。

In this work, the crystal structure and electrochemical charge/discharge properties of LaCo13-xNix(0 ≤x≤ 6) pounds were studied. It was found that when x≤2, the samples were composed mainly of the LaCo13 type compound. The heat-treatment had a very important effect on the forming of the LaCo13 type compound. The electrochemical experimental results showed that:The electrochemical capacities of LaCo13-xNix (0≤x≤2) compounds increased with increasing temperature. The substitution of Ni for Co increased the electrochemical capacity of the LaCo13-xNix compounds obviously when x≤0.8. When x ≤0.8, the electrochemical capacities of the LaCo13 - x Nix compounds changed very little with increasing Ni content. The highest electrochemical capacity of the LaCo13-xNix(0.8≤x≤2) compounds was about 359mAh/g at 60mA/g charge/discharge current density which was obtained at about 70℃ . We believed that the electrochemical capacities of the LaCo13-xNix compounds associated with the absorption and desorption of hydrogen atoms as were similar to the LaNi5 type compounds. The disadvantages of the LaCo13-x-Nix, compounds were their lower electrochemical capacity at room temperature and the poor cycle lifetime due to the dissolution of Co atoms in the KOH electrolyte. The amount of Co dissolved increased with increasing temperature.