Molten salt synthesis of LiMn 1 . 2 Ni 0 . 3 Cr 0 . 1 Co 0 . 15 Al 0 . 23 La 0 . 02 O 4 as a positive electrode for lithium‐ion batteries

Abstract

The molten salt synthesis method became an excellent synthesis technique to elaborate nanomaterials because of its meritorious advantages including low cost, easy to scale up, simple to operate, and environmental friendliness. For this reason, the compound LiMn1.2Ni0.3Cr0.1Co0.15Al0.23La0.02O4 was synthesized for the first time by molten salt method using NaCl as the salt and a nonstandard manganese source with metallurgical grade. The obtained cathode material was analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transformer infra-red (FT-IR), and electrochemical characterization. XRD and FT-IR results confirm the stability and formation of pure spinel phase without any impurities. TEM images showed that the spinel synthesized phase consists of 77 to 135 nm-sized polyhedral nanoparticles. The cyclic voltammogram results showed that the synthesized spinel cathode material exhibits two-main redox peaks at 4.06/3.9 V and 3.1/2.8 V vs Li+/Li, which indicate the possibility of insertion of extra lithium in the spinel structure. Galvanostatic charge-discharge studies were also carried out showed that the prepared spinel material has two discharge plateaus in the potential window of 1.5 to 5 V and a discharge capacity of 179 mAh g−1 at 0.1 C, which is higher than the theoretical value which confirms the insertion of extra lithium in the spinel structure and enhance the capacity of the cathode material. The electrochemical impedance spectroscopy was performed, and the Li-ion diffusion coefficient was also calculated.