摘要
镍氢电池负极材料对电池的低温放电性能和循环寿命至关重要,稀土-镁-镍系储氢合金容量高、易活化、倍率放电性能好,符合城轨车辆镍氢电池长寿命、低温放电的需求。本文采用感应熔炼法制备了La_(0.55)Sm_(0.20)Nd_(0.10)Mg_(0.15)Ni_(3.60)Al_(0.10)合金,进行了退火处理,并研究了合金的微观结构与电化学性能。结果表明,铸态合金由Ce_(2)Ni_(7)型、Ce_(5)Co_(19)型和LaNi_(5)型相组成,经过退火处理后,Ce_(2)Ni_(7)型与LaNi_(5)型相发生包晶反应,合金中的物相转变为Pr_(5)Co_(19)型相、Ce_(5)Co_(19)型相和LaNi_(5)型相。退火合金的放电容量可以达到380 mAh/g,经过100次充放电循环后,合金的容量保持率仍可以达到84.5%,略高于铸态合金。由于表面与晶体体相内部缺陷与非平衡组织的存在,铸态合金的表面电荷转移速率与内部氢扩散速率均较快,因此倍率放电性能和低温性能略高于退火合金。铸态储氢合金5C下的高倍率放电性能可达到76%,-40℃的放电容量可以达到208 mAh/g。以铸态合金为负极活性物质制备镍氢电池,所有测试均满足碱性电池相关的标准规定,且循环2350次放电容量仍可达91.8%,-40℃低温放电保持率达到97.0%。
The negative electrode material of nickel-metal hydride battery is very important to the low temperature performance and cycle life of the battery.The rare-earth-Mg-Ni-based hydrogen storage alloy has high capacity,easy activation and good rate discharge performance,which meets the demand of long life and low temperature discharge of nickel-metal hydride batteries of urban rail vehicles.In this work,La_(0.55)Sm_(0.20)Nd_(0.10)Mg_(0.15)Ni_(3.60)Al_(0.10)alloy was prepared by induction melting method,and followed by annealing treatment.Subsequently the microstructure and electrochemical properties of the alloys were studied.The results show that the as-cast alloy consists of Ce_(2)Ni_(7),Ce_(5)Co_(19),and LaNi_(5) phases.After annealing at 990℃ for 8 hours,the Ce_(2)Ni_(7) and LaNi_(5) phases undergo peritectic reactions,and the phases in the alloy transform into Pr_(5)Co_(19),Ce_(5)Co_(19),and LaNi_(5) phases.The discharge capacity of annealed La_(0.65)Sm_(0.20)Mg_(0.15)Ni_(3.60)Al_(0.10)alloy is as high as 380 mAh/g.After 100 charge discharge cycles,the capacity retention rate is still up to 82.6%,slightly higher than that of the as cast alloy.Due to the presence of defects and in-equilibria structures on the surface and crystal phases,the surface charge transfer rate and internal hydrogen diffusion rate of as-cast alloys are both relatively faster,resulting in slightly higher rate discharge performance and low-temperature performance.The high rate discharge performance of the as-cast hydrogen storage alloy at 5C is 76%,and the discharge capacity at -40℃ reach up to 208 mAh/g.All tests of Ni/MH batteries with as-cast alloy as the negative active material meet the relevant standard provisions of alkaline batteries,and the discharge capacity of 2350 cycles is still 91.8%,and the low temperature discharge capacity retention rate at -40℃ reaches 97.0%.
作者
郭团生
李媛
韩树民
GUO Tuansheng;LI Yuan;HAN Shumin(Kunming Metro Construction Management Co.Ltd.,Kunming,Yunnan 650051,China;School of Environmentaland Chemical Engineering,Yanshan University,Qinhuangdao,Hebei 066004,China)
出处
《燕山大学学报》
CAS
北大核心
2024年第5期463-470,共8页
Journal of Yanshan University
基金
国家自然科学基金资助项目(52071281)。
关键词
城轨车辆
镍氢电池
储氢合金
长寿命
低温放电性能
rail transit
Ni/MH battery
hydrogen storage alloy
long life
low temperature discharge property
