الفهرس | Only 14 pages are availabe for public view |
Abstract At present, lithium-ion batteries (LIBs) have been widely used in the field of new electric vehicles. The energy density of such a battery system for new electric energy vehicle is required to be high enough for meeting the requirement of vehicle mileage. In this regard, the cathode active materials of LIBs are crucial for the electrochemical performance, including capacity, energy density, and cycle life. In this thesis, facile coprecipitation method is used to coat LiNi0.8Mn0.1Co0.1O2 (NMC811) cathode material by spinel ZnAl2O4 (ZAO) nanoparticles layer and perovskite-type ZnSnO3 (ZTO) film for Lithium-ion batteries (LIBs). For physicochemical characterization, the effects of different contents of ZAO and ZTO coating layers on NCM811 particle surface on the morphologies, structures, and compositions of the prepared cathode materials are systematically studied using XRD, SEM, EDX, TEM, FTIR, and Raman spectroscopy. Coin cells (CR 2032) are assembled with such coated NMC811 cathode materials for performance evaluation. Electrochemical tests showed that the ZAO and ZTO coatings can stabilize the NMC811 active materials resulting in a good performance of rechargeable LIBs. The 0.25% ZnAl2O4 coated sample delivers high capacity retention " ~ "82% than that of pristine NMC811 " ~ " 60.2% after 100 cycles upon 1 C. The reduction in the separation potentials of both anodic and cathodic CV scans gives a strong indication for enhancing the structure stability and lowering the polarization between NMC811 particles. The cathode sample 1% ZTO@NMC811 showed higher rate capability performance than pristine NMC811, maintaining about 73% of its initial capacity even after re-cycling at 0.1C between cycle no. 25 and 30 and The enhanced electronic and ionic conduction after ZnSnO3 film coating was certified by the significant decrease in Ohmic (Rs) and charge transfer (Rct) resistances before and after cycling. |