摘要
高镍三元正极材料LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)(NCM,x≥0.6)具有能量密度高、成本合理等优势,是目前最具发展潜力的锂离子电池正极材料之一.然而,NCM在高截止电压下(≥4.3V)会出现加剧的不可逆相变、阳离子混排及过渡金属溶出等问题,这极大地阻碍了其商业化进程.本文中选用Ca^(2+)对LiNi_(0.7)Co_(0.15)Mn_(0.15)O_(2)(NCM70)材料进行掺杂改性,采用共沉淀法制备出前驱体LiNi0.7Co0.15Mn0.15(OH)2,随后通过高温固相法合成不同Ca^(2+)掺杂量的NCM70正极材料,并探究了Ca^(2+)掺杂量对材料晶体结构、表面形貌、电化学性能的影响及其失效机制.结果表明:与本体NCM70材料相比,Ca^(2+)掺杂改性的样品电化学性能得到显著提升;当掺杂量为0.5%时,NCM70-0.5%Ca材料具有最优的改性效果,它在倍率1 C、电压2.95~4.5 V下,首圈放电比容量为181.2 mAh/g, 150圈循环后仍维持其初始容量的71.3%.
LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)(NCM,x≥0.7)is one of the most promising cathode materials for lithium-ion batteries(LIBs)owing to the advantages of high energy density and reasonable cost.However,NCM suffers from problems such as aggravated irreversible phase transformation,cation mixing,and transition metal dissolution at high cut-off voltage(≥4.3 V),which greatly hinders its commercialization process.In this paper,Ca^(2+)was used to doping the LiNi_(0.7)Co_(0.15)Mn_(0.15)O_(2)(NCM70)material,and the precursor Ni_(0.7)Co_(0.15)Mn_(0.15)(OH)_(2) was prepared by co-precipitation method.Subsequently,NCM70 cathode materials with different Ca^(2+)doping amounts were synthesized by the high-temperature solid-state method,and the effect of Ca doping concentration on the crystal structure,surface morphology,electrochemical performance,and failure mechanism were explored.The results show that compared with the bulk NCM70 material,the electrochemical performance of the sample modified by Ca^(2+)doping is significantly improved.When the Ca^(2+)doping content is 0.5%,the modification effect of NCM70-0.5%Ca is the best.At a current density of 1 C and voltage of 2.95~4.5 V,the specific discharge capacity of the initial capacity remains 71.3%after 150 cycles.
作者
陈彦恒
田小龙
Chen Yanheng;Tian Xiaolong(Henan Intelligent Safety Engineering Research Center for Rail Transit,Zhengzhou 450018,China;Zhengzhou Railway Vocational Technical College,Zhengzhou 450052,China)
出处
《材料与冶金学报》
CAS
北大核心
2023年第6期566-572,共7页
Journal of Materials and Metallurgy
基金
河南省科技攻关资助项目(212102310457)。