三元材料LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)的制备及Na^(+)掺杂改性研究  

Study on preparation and Na^(+)doping modification of ternary material LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)

作　　者：杨福 解玉龙 YANG Fu;XIE Yulong(School of Chemistry and Chemical Engineering,Qinghai Minzu University,Key Laboratory of Resource Chemistry and Eco-environmental Protection in Tibetan Plateau of State Ethnic Affairs Commission,Qinghai Provincial Key Laboratory of Nanomaterials and Nanotechnology,Xining 810007,China)

机构地区：[1]青海民族大学化学化工学院,青藏高原资源化学与生态环境保护国家民委重点实验室,青海省纳米材料与技术重点实验室,青海西宁810007

出　　处：《无机盐工业》2025年第3期43-49,共7页Inorganic Chemicals Industry

基　　金：青海省应用基础研究项目(2024-ZJ-787)。

摘　　要：高镍三元正极材料LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(NCM)因具有比容量高、成本低、环境友好等特点被广泛应用,但其较高的镍含量导致阳离子混排严重,循环和倍率性能差。为了改善上述存在的不足,元素掺杂是一种降低阳离子混排程度和增强结构稳定性的有效策略。采用共沉淀法制备了Na^(+)掺杂LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(NCM-x%Na)正极材料(其中x%为物质的量分数)。通过X射线衍射(XRD)和扫描电子显微镜(SEM)手段对NCM-x%Na材料进行形貌和结构表征,通过充放电测试系统对其电化学性能测试。结果表明:Na^(+)掺杂可以有效减小颗粒尺寸和抑制阳离子混排程度,扩大了锂层间距,从而有助于提高锂离子的扩散速率;当x=2时Na^(+)掺杂LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)样品(NCM-2%Na)有最佳的电化学性能,在2.7~4.4 V、0.1C下循环100次后放电比容量为139.0 mA·h/g(容量保持率为86%),较NCM高出17%;在2.0C下NCM-2%Na材料放电比容量为82.2 mA·h/g,远远高于未改性的LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(39.4 mA·h/g);在0.1C、0.2C、0.5C、1.0C、2.0C下对其倍率性能测试,其中0.1C倍率下循环25次后NCM-2%Na容量保持率为90%,较NCM高出9%;反应动力学显示,NCM-2%Na有更小的电荷转移电阻,且锂离子扩散系数要高于NCM,使电荷传输动力学得到提升。The high-nickel ternary cathode material LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(NCM)is widely used because of its high specific capacity,low cost,and environmental friendliness,but its high nickel content leads to severe cation mixing and poor cycling and rate performance.In order to improve the above mentioned deficiencies,elemental doping is an effective strategy to reduce the degree of cation mixing and enhance the structural stability.Na^(+)-doped LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(NCM-x%Na)anode materials were prepared by co-precipitation method(where x%was the fraction of substance).The NCM-x%Na material was characterized morphologically and structurally by means of X-ray diffraction(XRD)and scanning electron microscopy(SEM),and its electrochemical properties were tested by means of a charge-discharge test system.The results showed that Na^(+)doping could effectively reduce the particle size and inhibit the degree of cation mixing,and enlarge the lithium layer spacing,which could help to improve the diffusion rate of lithium ions.The Na^(+)-doped LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)sample(NCM-2%Na)had the best electrochemical performance when x=2.The discharge specific capacity after 100 cycles at 2.7~4.4 V,0.1C was 139.0 mA·h/g(capacity retention of 86%),which was 17%higher than that of NCM.The discharge specific capacity of NCM-2%Na material at 2.0C was 82.2 mA·h/g,which was much higher than that of unmodified LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2)(39.4 mA·h/g).The multiplication performance was tested at 0.1C,0.2C,0.5C,1.0C,and 2.0C.The capacity retention of NCM-2%Na was 90%after 25 cycles at 0.1C,which was 9%higher than that of NCM.The reaction kinetics showed that NCM-2%Na had a smaller charge transfer resistance and a higher lithium ion diffusion coefficient than NCM,resulting in enhanced charge transfer kinetics.

关 键 词：高镍 正极材料 LiNi_(0.65)Co_(0.15)Mn_(0.2)O_(2) Na^(+)掺杂 倍率性能 

分 类 号：TQ131.1[化学工程—无机化工]