铝掺杂对无钴正极LiNi_(0.90)Mn_(0.10)O_(2)结构及电化学性能的影响

Effect of Aluminum Doping on the Structure and Electrochemical Properties of Cobalt Free Cathode LiNi0.90Mn0.10O2

采用共沉淀法将质量分数3%的Al取代Mn掺入二元Ni_(0.90)Mn_(0.10)OH_(2)前驱体中,经高温固相烧结合成一种无Co高Ni三元正极LiNi_(0.90)Mn_(0.07)Al_(0.03)O_(2),并通过X射线衍射(X ray diffraction,XRD)、扫描电子显微镜(scanning electron microscope,SEM)、能量弥散射线谱(energy dispersive spectroscopy,EDS)等表征手段进行分析,探讨了Al^(3+)掺杂对材料结构及性能的影响。结果表明,引入Al^(3+)后,Ni_(0.90)Mn_(0.07)Al_(0.03)OH_(2)一次颗粒明显变细,对应LiNi_(0.90)Mn_(0.07)Al_(0.03)O_(2)结晶度明显提高。在25℃、3.0~4.3 V下充放电,掺杂材料的0.1C比容量为191.3 mAh/g,高于未掺杂材料的181.5 mAh/g;0.5C循环90次的容量保持率为92.0%,高于未掺杂材料的89.3%;高温45℃下循环容量保持率为90.7%,高于未掺杂材料的92.2%。材料性能的提升可归因于Al^(3+)掺杂使得材料结晶度升高,稳定性提升,Li+传递势垒降低。

In this paper,the co-precipitation method was used to insert 3%Al substituted Mn into binary Ni_(0.90)Mn_(0.10)OH_(2)precursor,and a kind of high Ni ternary cathode LiNi_(0.90)Mn_(0.07)Al_(0.03)O_(2)without Co was synthesized by high temperature solid-phase sintering,and analyzed by X Ray Diffraction(XRD),Scanning Electron Microscope(SEM),Energy Dispersive Spectroscopy(EDS)and other characterization methods.The influence of Al^(3+)doping on the structure and properties of the materials was discussed.The results showed that the Ni_(0.90)Mn_(0.07)Al_(0.03)OH_(2)particles became fine obviously after the in-troduction of Al^(3+),and the corresponding crystallinity of LiNi_(0.90)Mn_(0.07)Al_(0.03)O_(2)was in-creased obviously.The specific capacity of 0.1C doped material is 191.3 mAh/g at 25℃and 3.0~4.3 V,which is higher than that of undoped material 181.5 mAh/g.The reten-tion rate of 90 cycles at 0.5C is 92.0%,which is higher than that of the undoped materi-als(89.3%).The retention rate of cyclic capacity at 45℃is 90.7%,which is higher than that of undoped material 92.2%.The improvement of material performance can be attributed to the increase of crystallinity and stability of the material caused by Al^(3+)doping,and the decrease of Li+transfer barrier.