Significantly improved cycling stability for electrochemical hydrogen storage in Ti1.4V0.6Ni alloy with TiN

Ti_1.4V_0.6Ni alloy contained icosahedral quasicrystals can be electrochemically charged and discharged with the maximum capacity of approximately 270 mAh g⁻¹, however this alloy shows poor cycling stability, making it difficult to develop the practical application. Here, new TiN-added Ti_1.4V_0.6Ni composites are prepared by ball-milling. The electrochemical performance of the composites as negative active ingredient of Nickel-metal hydride(Ni-MH) battery is compared with Ti_1.4V_0.6Ni. Benefiting from the excellent catalysts for HER, electrical conductivity and resistance to oxidation/corrosion of TiN, TiN-added Ti_1.4V_0.6Ni composites exhibit excellent cycling stability as well as charge retention(89.7% after 24 h relaxation). The cycling capacity retention rate for these electrodes is approximately 80% after a preliminarytest of 50 continuous cycles. But meanwhile, the maxium discharge capacity falls into about 250 mAh g⁻¹, and the electrocatalytic activity improvement is hightly demanded.This work presents a practical method for using TiN as an additive for enhancing the cycling stability of hydrogen storage alloy.