无镨钕AB_5型Mm(Ni,Co,Mn,Al)_5合金储氢及电化学性能研究

Properties and Electrochemical Performance of Pr/Nd-Free Mn(Ni,Co,Mn,Al)_5 Hydrogen Storage Alloy

镍氢电池是目前国内外混合动力汽车的首选电池,但随着稀土价格的不断上涨,稀土元素占其成本的比例约由14%逐步提升到55%,开发无镨、钕的高丰度镧铈稀土元素AB5型储氢材料,有助降低混合动力车用镍氢电池负极材料的成本。采用中频感应熔炼配合快淬甩带工艺制备了LaxCe1-x(NiCoMnAl)5(x=0.8,0.6,0.4)合金,并研究了合金A,B侧各元素的比例以及制备工艺对合金储氢性能及电化学性能的影响。结果表明,随着x的降低,合金的储氢量和放电容量逐渐降低。当x=0.6时,合金电极具有较好的综合电化学性能,最大放电容量达到332.81 mAh.g-1,充放电循环寿命达(715 mA.g-1,80%容量保持率,下同)215次。对该合金B侧Mn,Al含量进行优化后,原材料中的Co含量减少,合金的最高电化学容量可达319.01 mAh.g-1。合金在氩气氛保护下进行退火处理后,结晶度和均匀性上升,电化学容量有所降低,但循环稳定性得到明显改善。其中,经950℃/2 h退火处理的LaxCe1-x(NiCoMnAl)5(x=0.8)合金的最大放电容量达328.07 mAh.g-1,充放电循环寿命达364次。

The Nickel-Metal Hydride（Ni-MH） battery is the preferred batteries used for hybrid vehicles at home and abroad,But with the rising price of rare earths（especially Pr and Nd）,the cost proportion of rare earths in the Ni-MH battery has already increased from 14% to 55%.Hence,developing free-PrNd and high abundance of LaCe rare earth AB5-type hydrogen storage alloys,will help to reduce the cost of hybrid vehicle′s Ni-MH battery negative electrode material.In this paper,LaxCe1-x（NiCoMnAl）5（x=0.8,0.6,0.4） alloy was prepared by medium frequency induction melting with rapid quenching,and its hydrogen storage properties and electrochemical performance were researched on the influence by adjusting A,B side element′s content and annealing treatment process.The results showed that the hydrogen storage capacity and the discharge capacity of alloy gradually decreased decline of x.When x=0.6,the alloy electrode had the best comprehensive electrochemical performance,the maximum discharge capacity of alloy electrode was 332.81 mAh·g-1,and the cycle life of charge-discharge was 215 times（715 mA·g-1,80% capacity retention rate,the same as below）.After optimization of Mn,Al content in the B-side of alloy,the cobalt content in the raw materials reduced and the maximum electrochemical capacity reached 319.01 mAh·g-1.Through the annealing treatment under the protection of argon gas,the degree of crystallinity and the uniformity of the alloy were enhanced,and the electrochemical discharge capacity decreased slightly,but the cycle stability improved significantly.Among the annealing treatment process,when the LaxCe1-x（NiCoMnAl）5（x=0.8） alloy electrode was annealed at 950 ℃ for 2 h,the maximum discharge capacity reached 328.07 mAh·g-1 and the cycle life of charge-discharge was up to 364 times.