| Now has developed a number of hydrogen storage alloy, La-Mg-Ni alloy was concerned bya large discharge capacity.But thebiggest bottleneck thattheapplication of its cyclelife isnot better,how to ensure that the maximum discharge capacity of the foundation to improve the cycle life is tosolve the most critical issues that in the field of La-Mg-Ni hydrogen storage alloy applications.Atpresent, many of the key theories of the Department of La-Mg-Ni-based hydrogen storage electrodealloys A2B7at home and abroad, including the recession cycle stability mechanism alloy materials,alloy composition and structure as well as its electrochemical kinetic performance impact, improveitsoverallperformancemulti-alloying, etc. needto beaddressed and improved.Based on the La-Mg-Ni A2B7type alloy as substrate in this article. Medium frequencyvacuum induction furnace melting of La0.82Mg0.18Ni3.5-xAlx(x=0.05,0.10,0.15,0.20) cast alloy,combined with the material structure characterization results of XRD analysis of alloy composition,process control agent, milling time and factors that influence catalyst structure and electrochemicalpropertiesof thealloy.For La0.82Mg0.18Ni3.5-xAlx(x=0.05,0.10,0.15,0.20) alloy project a three factors, four levelsexperiment scheme. Get the optimum conditions the capacity retention rate is the amount of Alsubstitution0.20, tetrahydrofuran volume6ml, milling time was20min,20cycles of capacityretention rate of63.19%; maximum discharge capacity of the optimum conditions is the amount ofAl substitution0.05, tetrahydrofuran volume10ml milling time was20min discharge capacity of up356.2mAh/g. With the reduction of tetrahydrofuran, and the main Al alloy replacement levelincreases the amount of phase and are in phase and LaNi5phase and La2Ni7little change in theoverall phase structure, La2Ni7phase decreased, LaNi5phase gradually increased.Cell parameters a-axes and c-axes are LaNi5and La2Ni7phase increases linearly varying degrees, while a slightincreases in unit cell volume. EIS, the exchange current density characterization of surface chargetransfer rate lower electrode; hydrogen diffusion coefficient in vivo characterization of hydrogendiffusion rate of decline after fall and then upgrade, these is coincides with HRD. It is indicating that high-rate discharge performance alloy surface by charge transfer hydrogen diffusion rate and therateofinvivocomprehensiveconstraints.La0.82Mg0.18Ni3.45Al0.05+x wt.%TiO2（x=0~0.4）are made from alloys LaNi5phase and themain phase of the phase La2Ni7multiphase structure, with increasing the content of TiO2and MgNi2TiNi3hetero phase appears. The series alloys have excellent activation performance. Although theincrease in TiO2reduces the discharge capacity but for cycling stability has been significantlyimproved. At same time, it is also weakened the high rate discharge capability, which is perfectlymatch with its EIS, linear polarization and hydrogen diffusion coefficient is shown by the law,explained by the high-rate discharge performance alloy and alloy surface charge transfer rate ofhydrogen diffusionratein vivointeraction.Study on the dynamic performance La0.82Mg0.18Ni3.30Al0.20+x wt.%TiO2（x=0~0.4） seriesalloys. With the increasing content of TiO2alloy after high discharge capacity increased anddecreased, when x=0.3for the maximum. The overall trend is performanced by alloy surfacecharge transfer rate and exchange current density EIS was to reduce. Hydrogen diffusion coefficientis consistent with the law of the high-rate discharge performance. The high-rate dischargeperformance is mainly explained by the diffusion rate of hydrogen alloy body. Alloy cycle stabilityfirst and then decreased to improve the performance of the best when x=0.3. The alloy TiO2chemicaldoseof0.3relativehasthebestoverallperformance. |
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