铬钼双掺杂调控富锂锰基正极材料结构和电化学性能  

Cr/Mo co-doped regulation on structure and electrochemical performance in Li-rich manganese-based cathode materials

作　　者：陈会明 蔡艺嘉 尹文骥 陈美芬 黄有国 胡思江 王红强 李庆余 CHEN Huiming;CAI Yijia;YIN Wenji;CHEN Meifeng;HUANG Youguo;HU Sijiang;WANG Hongqiang;LI Qingyu(Jiangxi Ecological Environment Monitoring Center,Nanchang 330039,Jiangxi,China;Guangxi Key Laboratory of Low Carbon Energy Materials,School of Chemistry and Pharmaceutical Sciences,Guangxi Normal University,Guilin 541004,Guangxi,China)

机构地区：[1]江西省生态环境监测中心,江西南昌330039 [2]广西师范大学化学与药学学院,广西低碳能源材料重点实验室,广西桂林541004

出　　处：《储能科学与技术》2025年第3期1123-1132,共10页Energy Storage Science and Technology

基　　金：广西省自然科学基金杰出青年基金(2024GXNSFFA010003)。

摘　　要：富锂锰基正极材料比商业化的正极材料拥有更高的比容量(>250 mAh/g),但其在充放电过程中存在严重电压衰减、表面相变以及晶格氧的析出等问题。本工作采用高温固相法制备Cr/Mo双掺杂Li_(1.2)Ni_(0.167)Co_(0.167)Mn_(0.666)O_(2)(LLO)富锂锰基层状正极材料。研究结果表明,一方面,Mo^(6+)的离子半径较大,占据过渡金属位后能够有效增大晶面间距,提升Li^(+)扩散系数,Cr掺杂能有效稳定层状结构;另一方面,Cr—O和Mo—O的键能高于TM—O(TM=Ni,Co,Mn),能够有效缓解充放电过程中的结构畸变,从而抑制过渡金属迁移和晶格氧析出。此外,材料表面丰富的氧空位能够减少晶格中氧的不可逆氧化。电化学测试结果表明,Cr/Mo两者掺杂量皆为0.001的改性材料(LLO-CM1)首次放电比容量达272.7 mAh/g,在1 C倍率下2~4.8 V电压范围内进行200次循环之后,仍有177.7 mAh/g的比容量,对应的容量保持率为84.0%,即使在10 C超大倍率下也能提供102.0 mAh/g的平均放电比容量。本工作为富锂锰基正极材料的结构设计提供了新思路。Li-rich manganese-based cathode material has a higher capacity(>250 mAh/g)than common commercial cathode materials,but it is plagued by severe voltage decay,surface phase transitions,and lattice oxygen evolution during cycling.To address these issues,this paper designs a Cr/Mo co-doped Li_(1.2)Ni_(0.167)Co_(0.167)Mn_(0.666)O_(2)(LLO)cathode material using a high-temperature solid-state method.The results show that stability and electrochemical performance are improved after this modification.On one hand,the large ionic radius of Mo^(6+)increases lattice spacing,while Cr doping stabilizes the layered structure.Conversely,the higher bond energies of Cr—O and Mo—O effectively mitigate structural distortion,resulting in reduced transition metal migration and oxygen release.Moreover,abundant surface oxygen vacancies lower irreversible oxygen redox.Electrochemical measurements display that the cycle performance and rate capability of LLO-CM1 are enhanced.In particular,LLO-CM1 delivers an initial discharge specific capacity of 272.7 mAh/g and maintains 177.7 mAh/g after 200 cycles in the voltage range of 2—4.8 V at 1 C,corresponding to a capacity retention of 84.0%,while an average discharge specific capacity of 102.0 mAh/g is delivered even at 10 C.The co-doped strategy sheds light on designing Lirich manganese-based cathode materials.

关 键 词：锂离子电池 层状氧化物 富锂锰基 掺杂 氧空位 

分 类 号：TQ152[化学工程—电化学工业]