Na_(0.44)MnO_(2)包覆Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2)材料的性能

Performance of Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2) material coated with Na_(0.44)MnO

采用溶胶-凝胶法在富锂Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);材料表面包覆Na_(0.44)MnO_(2),制备Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);/Na_(0.44)MnO_(2)复合材料,以改善循环性能。XRD、X射线光电子能谱(XPS)、SEM和透射电子显微镜(TEM)分析结果表明:制备的复合材料为核壳结构,在高温固相反应形成Na_(0.44)MnO_(2)时,不影响Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);的固有结构。循环伏安(CV)、恒流充放电(GCD)测试结果表明:包覆Na_(0.44)MnO_(2)的复合材料,脱锂电位正移、嵌锂电位基本不变;放电比容量降低,但首次库仑效率、容量保持率提高,循环稳定性得到改善。以不同倍率在2.0~4.8 V循环后,30 mA/g充放电的比容量恢复到173 mAh/g,容量恢复率为100.0%;以300 mA/g循环200次的容量保持率为77.3%,较未包覆材料提高28.6%。

Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);/Na_(0.44)MnO_(2)composites were prepared by coating Na_(0.44)MnO_(2)on the surface of lithium-rich Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);material using sol-gel method in order to improve cycle performance.The results of XRD,X-ray photoelectron spectroscopy(XPS),SEM and transmission electron microscope(TEM) analysis showed that the prepared composites were core-shell structure.The inherent structure of Li_(1.2)Ni_(0.13)Co_(0.13)Mn_(0.54)O_(2);was almost unaffected in the process of forming Na_(0.44)MnO_(2)by high-temperature solid-phase reaction.Cyclic voltammetry(CV) and galvanostatic charge-discharge(GCD) test results showed that the delithiation potential of the composites coated Na_(0.44)MnO_(2)had a positive offset, the lithium insertion potential was almost unchanged.The specific discharge capacity decreased, but the initial Coulombic efficiency and capacity retention rate increased, the cycle stability was improved.After cycled at different rates in 2.0-4.8 V,the specific capacity of charged-discharged at the current of 30 mA/g restored to 173 mAh/g, the capacity recovery ratio was 100.0%.The capacity retention rate was 77.3% after 200 cycles at the current of 300 mA/g, which was 28.6% higher than that of uncoated one.