LiNi0.6Co0.2Mn0.2O2正极材料的TiO2包覆改性

Surface modification of LiNi0.6Co0.2Mn0.2O2 coated with Ti02

为改善LiNi0.6Co0.2Mn0.2O2一次料性能,采用简便易行的干法包覆方式进行处理。研究了TiO2包覆量一定时热处理温度、保温时间对材料的物理指标,以及容量、倍率、循环寿命和存储等电性能的影响。X射线衍射(XRD)、扫描电镜(SEM)等分析结果表明,当热处理温度500℃、保温时间12h时,材料表面有明显包覆物,但无新物相生成。3.0~4.3V下扣式电池0.1C放电容量为181.2mA·h/g,比未包覆材料的提高2.6mA·h/g;在3.0~4.4V下,45℃下1C充放电80周,循环保持率由未包覆的95%提升至97.2%。将热处理后材料制成600mA·h的小软包电池,在3.0~4.2V下,60℃放置7d后测试,包覆后样品鼓胀率由包覆前的8.3%降低到4.5%,容量保持率和容量恢复率分别由89.1%和90.2%提升到98.3%和99.1%。

In order to further improve the performance of LiNi0.6Co0.2Mn0.2O2 bare,the effects of heat treatment tcmperature and holding time on the physical and electrical propertics of bare are studied by a simple dry coating method.X-ray diffraction(XRD)and scanning electron microscopy(SEM)tests show that there are obvious coating substance on the surface of the material,but no new phase is fortmed.When hent treatment temperature is 500℃and holding time is 12 h,the discharge capacity of sample tested with coin cell is 181.2 mA·h/g at 0.lC over 3.0-4.3 V,which is 2.6 mA·h/g higher than that of uncoated,and its capacity retention increases from 95%to 97.2%after 80 cycles at 1C and 45℃over 3.0-4.4V.The coating material consumes the residual alkali of the bare surface,alleviates the chemical erosion of the electrolyte.The cycle life and storage performance af the material are improved.Full cell test shows that the swelling rate decreases from 8.3.%to 4.5%,and the capacity retention and capacity recovery increases from 89.1%and 90.2%to 98.3%and 99.1%,respectively.