The effect of carbon nanotubes on the electrochemical hydrogen storage performance of LaNi5 rare earth alloy

We have investigated the electrochemical hydrogen storage performances of LaNi5 electrodes doped with carbon nanotubes (CNTs); the CNTs were prepared by chemical vapor deposition using a rare earth alloy as catalyst in a C2H2/H2 atmosphere. A three-electrode system was introduced; the above electrodes were used as the cathodes of the electronic cell, NiOOH/Ni(OH)2 as the anodes, and Hg/HgO as the reference electrodes. A 6 M aqueous KOH solution was introduced as the electrolyte. When the LaNi5 electrode was doped with 10% carbon nanotubes to its active material, it had a capacity of 407 mAh/g under the charge/discharge current density 200 and 100 mA/g, respectively. The discharge voltage limit was set as 0 V. The discharge trend is steadier while discharge plateau is improved to 0.875 V. Furthermore, we compared the electrochemical hydrogen storage capability of the LaNi5 electrodes doped with different ratios of CNTs (15%, 10%, 7% and 5%) under the same charge/discharge condition and found that the optimum doped quantity of CNTs is 10% in our experiment confines. The polarization peculiarity of each electrode was tested by the Transistor Potentiostat, which exhibited that LaNi5 electrodes doped with CNTs of different ratios have different electrochemical activation character.