Specific Capacity and Capacity Fading of Interstitial and Substitutional Doping of Li in LiNi0.6Co0.3Ti0.1O2 Nano Cathode Material for High Energy Density Li-Ion Battery

Abstract

Pure and single phase LiNi0.6Co0.3Ti0.1O2, Li1.05Ni0.6Co0.3Ti0.1O2, Li1.05Ni0.55Co0.3Ti0.1O2 materials were successfully prepared using a self-propagating combustion method. The structure and morphology of the materials were characterized using X-Ray Diiffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-Ray Spectroscopy (EDX). The oxidation state of elements and their chemical environments were studied using X-Ray Photoelectron Spectroscopy (XPS). The electrochemical performances of the materials were carried by means of galvanostatic charge-discharge 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 discharge capacities are between 141 and 145 mAhg-1. The interstitially doped Li1.05Ni0.6Co0.3Ti0.1O2 compound exhibits the highest first cycle capacity of 145.3 mAhg-1 over the voltage range of 2.5 to 4.2 V compared to the undoped sample, LiNi0.6Co0.3Ti0.1O2, showing a capacity of 105.5 mAhg-1. The 70th cycle revealed that the Li interstitially doped material (Li1.05Ni0.6Co0.3Ti0.1O2) shows the highest specific discharge capacity of 132.4 mAhg-1. The capacity fading is only about 8.9% compared to 25.4% for undoped LiNi0.6Co0.3Ti0.1O2 and 10.4% for Li substitutionally doped material (Li1.05Ni0.55Co0.3Ti0.1O2). 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 Li1.05Ni0.6Co0.3Ti0.1O2 than the other two materials supporting the electrochemical behaviour of the materials.