Effects of Ba dopant on the structural, microstructural, and electrochemical properties of NCM811 cathode material (BaxLi1−xNi0.8Co0.1Mn0.1O2) for Li-ion storage

Abstract

The Ba-doped NCM 811 cathode material (Ba_xLi_1-xNi_0.8Co_0.1Mn_0.1O₂ (x = 0, 0.015, 0.03, 0.05)) was prepared by a facile chemical synthesis method. The structural, microstructural, and electrochemical properties were studied as a function of Ba content by X-ray diffractometry, X-ray photoelectron spectroscopy, scanning electron microscopy, galvanic charge/discharge, and electrochemical impedance spectroscopy (EIS) techniques. Single-phase NCM powders with the layered crystal structure were crystallized irrespective of the amount of Ba dopant. The unit cell volume expanded from 100.606 to 101.962 Å³ by adding the Ba cations. Furthermore, the particle size increased from 0.40 to 0.49 μm by increasing the Ba dopant up to 5 %. The Ba_0.03Li_0.97Ni_0.8Co_0.1Mn_0.1O₂ material had the highest discharge specific capacity of 185 mA h g^‐1 at a current rate of 0.1C and a high capacity retention of 99.8 % after 500 charge/discharge cycling at 1C. By adding the Ba cations, the diffusion coefficient calculated from EIS increased from 3.31 × 10⁻¹⁴ to 7.71 × 10⁻¹⁴ cm² s⁻¹ due to the expansion of the lattice structure.