储氢合金表面包铜电极电化学性能研究

STUDY ON ELECTROCHEMICAL CHARACTERISTICS OF Cu-COATED HYDROGEN STORAGE ALLOY

采用化学镀铜法对储氢合金进行表面包覆，用包覆粉制成的储氢电极，其放电容量、大电流充放电性能均得到了改善，１Ｃ全充放循环１００次，容量仅下降５％；未包覆粉制成的电极，其容量相应地损失了２１％。用此包覆粉组装成Ｎｉ／ＭＨ电池，１Ｃ／０２Ｃ达到９５％，１Ｃ全充放循环２００周期，容量衰减２０％。此外，初步探讨了储氢合金表面包铜的得与失。

Negative electrode was made of Cu-coated hydrogen storage alloy powders. The capacity decay was only 5% after 100 cycles compared with its saturated value at 25 0C (1C charge-discharge, 100% DOD).In addition, the charge-discharge characteristics were improved by the copper coating, especially at high rate charge/discharge due to the role of copper as a microcurrent collector forfacilitating charge transfer reaction on the alloy surface.Experimental Ni/MH battery (AA size) using Cu-coated alloy powders as anode materials showed a longer cycle life and a higher average discharge voltage than one using the bare alloy.Moreover, the results showed that after microencapsulation with copper, a little part of the capacity of hydrogen storage alloy was lost because of the existance of copper film with high overpotential of hydrogen evolution and poor electrocatalytic activity, causing an uncompleted contact between alloy and electrolyte.