Preparation And Electrochemical Properties Of Re-Mg-Ni-based Hydrogen Storage Alloys With Superlattice Structure

In recent years,with the rapid development of new energy vehicles,nickel-metal hydride battery is favored for its high safety.RE-Mg-Ni-based hydrogen storage alloy,as one of the key materials of nickel-hydrogen power batteries,has also become a hot topic of research.In this paper,the phase structure and electrochemical properties of La-Sm-Mg-Ni based hydrogen storage alloys of A₅B₁₉ and AB₄ types are studied,and to regard it as a kind of electrode materials with excellent comprehensive electrochemical properties for nickel-hydrogen power batteries.The La-Sm-Mg-Ni-Al based alloys has been prepared by an induction melting,and the electrochemical performance of A₅B₁₉ alloys with secondary phase has been investigated.The results show that,compared with Pr₅Co₁₉ single-phase alloy,the maximum discharge capacity of the alloy electrode increases when a small amount of Ce₅Co₁₉ secondary phase is contained.The high-rate property and the low-temperature property of the alloy are reduced.When Ce₅Co₁₉ as the main phase containing a small amount of Pr₅Co₁₉ secondary phase,the HRD₉₀₀ of the alloy electrode increases from57.2%to 59.8%,and the capacitance of the alloy electrode increases from 194.1 mAh/g to207.9 mAh/g at-40?.The high-rate property and low temperature property of the alloy electrode are improved.In order to study the electrochemical properties of AB₄ alloys,three La-Sm-Y-Mg-Ni-Al based alloys with different Y contents have been prepared by an induction melting,and the effects of Y on the phase structure and electrochemical properties of AB₄ alloy.After the Y content increases,the unit cell parameters and the unit cell volume both decrease.This is because the Y element partially replaces the A side element in the alloy,and the atomic radius of Y is smaller than La and Sm on the A side.Therefore,the unit cell parameters and the unit cell volume of the alloy decrease.At the same time,the cycle life of the alloy containing Y has been significantly improved.After activation of the alloy electrode,it was 2 weeks to reach its maximum discharge capacity.At the same time,with the increasing content of Y,the cycle life of the alloy electrode has been significantly improved.When the Y content increases from 0 to 0.05,the cycle life100^th increases from 85.6%to 90.0%.However,when the Y content continues to increase to 0.10,the cycle life 100^th decreases slightly,which is 88%.