Microstructure And Electrochemical Properties Of La-Y-Ni Based A₂B₇ Hydrogen Storage Alloys

In recent years,the rapid development of hydrogen storage cells,but there are still many problems,Oxides,Graphene and BFe material having excellent physical properties.In this paper,the microstructure and electrochemical properties of A₂B₇ hydrogen storage alloy(LaY₂Ni_9.5Mn_0.5Al_0.5)are investigated by adding these new materials to hydrogen storage alloys.The research content mainly includes the following three parts:the effect of the oxides addition on the properties of hydrogen storage alloys;the effect of graphene addition on the performance of hydrogen storage alloy;the effect of BFe-C composites on the properties of hydrogen storage alloys.From the XRD pattern,the crystal structure of the hydrogen storage alloy(LaY₂Ni_9.5Mn_0.5Al_0.5)with different oxides and graphene and BFe-C composites addition has not been changed.The unit cell structure of the alloys is mainly composed of two phases of Ce₂Ni₇ and Gd₂Co₇.It can be seen from the SEM image that the light and dark alternation can be observed,indicating that the two phases are uniformly distributed in the hydrogen alloy.Ball milling processing can make the alloy particles more uniform in size.Electrochemical studies show that the maximum discharge capacity and cycle stability of the alloy electrode are improved with oxides addition.The maximum discharge capacity of the alloy electrode with ZnO addition reaches 280.1 mAh/g;and the cycle stability S₁₀₀ of the alloy electrode with CuO addition is improved to 65.2%,the charge retention of the alloy electrode with CuO addition is improved;The high rate discharge performance of the alloy electrode with Pr₂O₃ addition is improved.The maximum discharge capacity and cycle stability of the alloy electrode with graphene addition are increased;and the discharge capacity of the alloy electrode with 3wt%graphene addition reaches 277.4 mAh/g.After 100 cycles,the discharge capacity of the alloy electrode with 3 wt%grapheme addition is higher than that of the reference alloy.At the high temperature,the alloy with graphene addition has a higher discharge capacity.A proper amount of grapheme addition can improve the high rate discharge performance of the alloy electrode;and 3 wt%graphene addition has better high rate dischargeperformance.The charge retention of the alloy electrode with 1 wt%graphene addition is improved.The charge retention of the alloy electrode with 3 wt%and 5 wt%grapheme addition decreases.With BFe-C composites addition,the maximum discharge capacity of alloy electrodes increases.The maximum discharge capacity of composite alloys increases with the content of BFe-C composites increase.The maximum discharge capacity with 15wt%BFe-C composites addition is 405.9 mAh/g.The alloy electrode with BFe-C composite addition has poor cycle stability and charge retention rate.With the temperature increases,the discharge capacity of the alloy electrode decreases.