Characteristics of electrochemical hydrogen storage of TiFe based alloys with Ni composite by mechanical milling

In this paper, Ti1.04Zr0.1La0.06Fe0.6Ni0.3Mn0.2 + x wt% Ni (x = 0, 2, 5, 7, 10) composite were prepared by ball milling for 1 h, and the effects of Ni powder addition on the structure, morphology and electrochemical properties of the alloy were investigated. As the results show that after ball milling for 1 h with Ni powder, the composite consists of TiFe, ZrMn2, and Ni triple phases. With increasing of Ni powder addition, the uniformity of Ni powder coating on the alloy surface is improved, and the discharge capacity, cycling stability and high-rate discharge (HRD) performance of the composite are significantly improved. The first discharge capacity of the x = 10% alloy was as high as 286.9 mAh/g, and the retention rate reaches 77.8% after 50 cycles, which is nearly 90% higher than that of the alloy with x = 0% alloy (38.7%). At a current density of 80 mA/g, the HRD value of the x = 10% alloy (59.4%) was improved by 97.8% compared to that of the non-Ni powder ball milling alloy (30.03%), and the kinetic parameters (D, IL and Rct) showed a trend consistent with the pattern of variation of high-rate discharge performance. The uniform coating of Ni powder with high electrical conductivity and excellent electrocatalytic activity on the alloy surface is a primary factor for the enhanced electrochemical properties of Ni composite. [Display omitted] •Ni powder coating significantly enhances the charge transfer rate in the alloy surface.•The first discharge capacity reached 286.9 mAh/g of the 10 wt%Ni composite alloy.•The 10 wt%Ni composite alloy achieved a capacity retention of 77.8% after 50 cycles.•The HRD of the 10 wt% Ni composite alloy increased by 97.8% compared to non-Ni alloy.