Study On Structure And Electrochemical Performance Of Ti-V-Mn Solid Solution Alloy

The purpose of this work is to improve electrochemical performance of Ti-V-Mn solid solution alloy. In this paper, compositon optimizing on Ti_1.0-xV_1.1Mn_0.5+xNi_0.4 (x=0, 0.1) alloy has been done, based on extensive analysis on current situation of research on hydrogen storage alloy.The structure, surface morphology and composition of the Ti_1.0-xV_1.1Mn_0.5+xNi_0.4(x=0,0.1) ,Ti_1.0 V_1.1-xMn_0.5Ni_0.4RE_x (RE stands for La,Ce,Pr,Nd, respectively;x=0, 0.05, 0.1, 0.15, 0.2) ,Ti_1.0 V_1.1Mn_0.5Ni_x(x=0.4,0.5,0.6,0.7,0.8,1.0) and Ti_1.0V_1.1-xMn_0.5Ni_0.7Cr_x(x=0,0.05,0.1,0.15,0.2) alloys were investigated by means of XRD and SEM-EDS analyses. It was shown that these alloys all consist of bcc main phase and C14 Laves or TiNi-based secondary phase,and the secondary phase precipitate along the grain boundary in the form of a network. Besides, RE-rich phase appeared in RE-added alloys.The influence of different element content on electrochemical performance of the alloy was also investigated by measuring P-C-T curves, discharge capacity, high-rate discharge ability and capacity retention. Although with the same content (at%) of Ni, Ti1.0V1.1Mn0.5Ni0.4 shows much excellent overall electrochemical properties than Ti0.9V1.1Mn0.6Ni0.4.Addition of RE made more appearance of C14 Laves phase in the alloy, and appropriate content of RE-rich phase which served as a electrocatalyst and micro-current collector, rising the maximum discharge capacity and high-rate dischargeability. With increasing Ni content, the C14 type Laves secondary phase in the alloy transfers into TiNi-based phase. Moreover, P-C-T isotherms indicated Ti_1.0V_1.1Mn_0.5Ni_0.7 alloy shows a higher desorption plateau pressure than Ti_1.0V_1.1Mn_0.5Ni_0.4 alloy. Addition of Cr improves cycle life and discharge capacity remarkably, while the alloy electrode requires more cycles to be fully activated.