Low-cost High-performance Hydrogen Storage Alloys

The development and foreground at present of Low_Co hydrogenstorage alloy are introduced. A series of Low_Co type hydrogen storagealloys is made by furnace melting.X-ray diffraction (XRD),Electrochemical Impedance Spectroscopy (EIS) and ICP are used to studyand analyze systematically the electrochemical performances (maximumdischarge capacity, high-rate capability and cycle performance) ofhydrogen storage alloys and their microstructure, kinetic characteristics.The results are shown as follows:(1) Hydrogen storage alloy stoichiometrically doping with iron orcopper, the crystal lattice parameters (a₀, c₀) value and crystal latticevolume are reduced, consequently the maximum discharge capacity andhigh-rate capability are deteriorated, but they have CuCa₅ structure andstrong X-ray diffraction peak. This shows that they have completelycrystal type.(2) The content of cobalt is important to the cost of hydrogen storagealloy. It is the primary way with using copper and iron to raplace cobalt toreduce the content of cobalt in hydrogen storage alloy. The result showsthat the iron affects the performance of hydrogen storage alloy seriously,the capacity reduces regradully with the content of iorn increasing. The0.5C capacity of the hydrongen storage alloy reduces obviously from308mAh/g to 257mAh/g when the content of iorn is 0.20. But thereplacing of copper almost doesn't affect the capacity of hydrogen storagealloy. The maxmum capacity is 301mAh/g when the content of copper is0.20. S₃₀₀ respective is 92.3％, 84.3％, 91.2％when the alloy is unreplacedand the replacing content of iorn or copper is 0.10.(3) When the content of copper is 0.1, the electromical performanceof the alloy isn't affected relative to the unreplacing alloy, but reducingthe cost by 3％-6％.(4)The test result of the alloy partly replaced by copper applying tobattery shows, replacing by copper doesn't affect the activationperformance and discharge capacity of the alloy, the inherent resistance, electric voltage and self-discharge can all satisfy the requirement ofbattery. Therefore, appropriately replacing by copper not only retains thegood electrochemical performance of alloy, but also reduces the cost ofthe materials.