摘要
通过一种简单高效的湿法包覆法对Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)2前驱体进行Al_(2)O_(3)包覆,在与Li_(2)CO_(3)混合后经过一次高温烧结工序制备得到Al包覆改性的LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2)层状正极材料(记作x%Al-NCM)。采用了XRD、SEM、EDS、TEM和电化学测试技术等方法对材料的结构、形貌、成分和充放电性能进行了表征分析,系统地研究了Al_(2)O_(3)包覆层对材料的电化学性能影响。结果表明,薄层Al_(2)O_(3)包覆结合近表面的微量Al^(3+)的晶格掺杂,有效降低了阳离子混排度并可明显改善NCM622材料的循环和倍率性能。0.4wt%Al-NCM材料在5 C倍率下放电容量为144.42 mAh/g(3.0~4.3 V),并且其在1 C下循环200次后的容量保持率可维持在85.39%,明显优于未包覆NCM的保持率(74.32%)。Al-NCM循环性能的显著增强归因于Al_(2)O_(3)包覆层阻挡了材料表面与电解液的接触,减少界面副反应,抑制了过渡金属溶解;同时该包覆层维持了稳定的层状结构,降低了电极极化现象,缓解了循环过程的不可逆的容量损失。
The Ni_(0.6)Co_(0.2)Mn_(0.2)(OH)_(2) precursor was coated with Al_(2)O_(3) by wet coating method,and the Al-coated LiNi_(0.6)Co_(0.2)Mn_(0.2)O_(2) layered cathode material(denoted as x%Al-NCM)was prepared via a high-temperature sintering process after mixing with Li_(2)CO_(3).The structure,morphology,composition and charge-discharge performance of the as-prepared Al-NCM materials were characterized by XRD,SEM,EDS,TEM and electrochemical testing methods.The results showed that thin Al_(2)O_(3) coating layer combined with trace Al^(3+)lattice doping near the surface could effectively reduce the cationic mixing degree and improve the cycling and rate performance of the NCM622 material.The 0.4wt%Al-NCM sample could achieve a capacity of 144.42 mAh/g at 5 C within the voltage of 3.0~4.3 V.Meanwhile,it could maintain the capacity retention of 85.39% after 200 cycles at 1 C,which was obviously superior to tha of thepristine NCM(74.32%).The significantly enhanced cycling performance of Al-NCM materials could be attributed to the Al_(2)O_(3) coating layer that could block the contact between the material surface and the electrolyte,reducing the interface side reaction and inhibiting the transition metal dissolution.At the same time,the coating layer maintained the stability of layered structures,thus reducing the polarization phenomenon of the electrode and alleviating the irreversible capacity loss in the cycle process.
作者
程正
陈愫英
李雪莎
周俊
朱淇才
樊浩杰
张彬
雷英
CHENG Zheng;CHEN Su-ying;LI Xue-sha;ZHOU Jun;ZHU Qi-cai;FAN Hao-jie;ZHANG Bin;LEI Ying(Yibin Libode new materials Co.,Ltd.,Sichuan Yibin 644000;Sichuan University of Science&Engineering,Sichuan Zigong 643002,China)
出处
《广州化工》
CAS
2024年第9期23-27,共5页
GuangZhou Chemical Industry
基金
晨光高性能氟材料创新中心项目(No.2022NSFSC1971)
四川省高等学校精细化学品与表面活性剂重点实验室(2022JXY04)
大学生创新创业训练计划项目(2022JXY04)。
