Molten salt synthesis of LiMn _{1 . 2} Ni _{0 . 3} Cr _{0 . 1} Co ₀

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 LiMn 1.2 Ni 0.3 Cr 0.1 Co 0.15 Al 0.23 La 0.02 O 4 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 À1 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.

A nano-truncated Ni/La doped manganese spinel material for high rate performance and long cycle life lithium-ion batteries

“…The average length of the Mn-O bond becomes short (from 0.1972 nm of the LiNi 0.08 Mn 1.92 O 4 to 0.1968 nm of the LiNi 0.08 La 0.01 Mn 1.91 O 4 ) owing to the high content of Mn 4+ and a smaller radius of Mn 4+ (0.067 nm) than that of Mn 3+ (0.072 nm). 18,38 What is more, the firmer energy of the Ni-O bond (1029 kJ mol À1 ) and La-O bond (799 kJ mol À1 ) than the Mn-O bond (402 kJ mol À1 ) also causes the MnO 6 skeleton to contract. 24 This suggests that the Ni-La co-doping can stabilize the crystal structure.…”

“…[14][15][16][17] Among them, element doping is acknowledged as a more satisfactory strategy to mitigate the Jahn-Teller effect. 18 Generally, the doped ions include Ni 2+ , 19 Cu 2+ , 20 Al 3+ , 21 La 3+ , 22 B 3+ , 23 etc. Owing to the relatively higher energy of the Ni-O bond (1029 kJ mol À1 ) and La-O bond (799 kJ mol À1 ) than that of the Mn-O bond (402 kJ mol À1 ), 24,25 the partial substitution of Ni 2+ and La 3+ for Mn 3+ in the spinel LiMn 2 O 4 will result in a strengthened metal-oxygen bond and form a stable octahedron MnO 6 , whilst suppressing the Jahn-Teller effect.…”