Specific Capacity and Capacity Fading of Interstitial and Substitutional Doping of Li in LiNi0.3Co0.3Mn0.3Ti0.1O2 cathode Material for High Energy Density Li-Ion

Pure and single phase LiNi_0.3Co_0.3Mn_0.3Ti_0.1O₂ , Li_1.05Ni_0.3Co_0.3Mn_0.3Ti_0.1O₂ and Li_1.05Ni_0.3Co_0.25Mn_0.3Ti_0.1O₂ materials were successfully prepared using a self-propagating combustion method. The structure and morphology of the materials were characterized using X-Ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and the elemental analysis were done using by Energy Dispersive X-Ray Spectroscopy (EDX). The oxidation state of element and their chemical environments were identified using X-Ray photoelectron Spectroscopy (XPS). The electrochemical performances of the materials were carried by means of galvanostatic charge-discharge test on the fabricated cells.  XRD results showed that the materials are impurity-free and single phase with well ordered hexagonal layered structure of R-3m space group. The different samples annealed at 700 °C for 48h showed variations in discharge capacities. The discharge capacities are between 130 and 141 mAhg^-1. The undoped LiNi_0.3Co_0.3Mn_0.3Ti_0.1O₂ compound exhibits the highest first cycle capacity of 141.3 mAhg^-1 over the voltage range of 2.5 to 4.2 V and the lowest capacity was 130.43 mAhg^-1 for sample Li_1.05Ni_0.3Co_0.25Mn_0.3Ti_0.1O₂. The 30^th cycle revealed that the Li interstitially doped material is (Li_1.05Ni_0.3Co_0.3Mn_0.3Ti_0.1O₂) shows the highest specific discharge capacity of 131.74 mAhg^-1. The capacity fading is only about 1.3% compared to 7.66% for undoped LiNi_0.3Co_0.3Mn_0.3Ti_0.1O₂ and 12.3% for Li substitutionally doped material (Li_1.05Ni_0.3Co_0.25Mn_0.3Ti_0.1O₂). The XPS studies showed that the binding energy of Li 1s is lowest for the best performance compound meaning that the Li⁺ ions can be extracted more easily from Li_1.05Ni_0.3Co_0.3Mn_0.3Ti_0.1O₂ than the other two materials. Therefore, XPS results show that the deintercalation of Li from the interstitially doped compound was much more efficient and enhanced the electrochemical performance of the material. The results also suggest that the self-propagating combustion method is a good synthesis method for the preparation of LiMn_0.3Co_0.3Ni_0.3Ti_0.1O₂ and their Li doped materials for applications in lithium-ion batteries.