Sulphur Substitution As an Effective Way to Promote the Structural and Electrochemical Performance of the LiMn2O4 Cathode Material
The aim of this work was to investigate how sulphur substitution affect the structural and electrochemical properties of LiMn2O4-ySyspinel materials.
Nanosized LiMn2O4-ySy (y = 0 or 0.01) spinel materials were obtained by a modified sol-gel method based on the hydrolysis and condensation processes. The prepared Li-Mn-O-S spinel systems were investigated with regard to the physicochemical properties using X-ray powder diffraction (XRD), elemental analysis (EA), nuclear magnetic resonance (NMR), low-temperature nitrogen adsorption-desorption measurements (N2-BET), differential scanning calorimetry (DSC) and electrical conductivity (EC) studies. The electrochemical performance of Li/Li+/LiMn2O4-ySycells was examined by galvanostatic charge/discharge tests (CELL TEST) and electrochemical impedance spectroscopy (EIS).
It was established that the introduction of a small amount of sulphur leads to the stabilization of the spinel structure and consequently, the enhancement of the cycling behavior what confirmed that sulphur substitution is an efficient way to advance the structural and electrochemical properties of the LiMn2O4spinel.
 J. M. Tarascon, M. Armand, Nature 414 (2001) 359-367.
 K. Amine, J. Liu, I. Belharouak, S. H. Kang, I. Bloom, D. Vissers, G. Henriksen, Journal of Power Sources 146 (2005) 111-115.
 R. Mukherjee, R. Krishnan, T. M. Lu, N. Koratkar, Nano Energy 1 (2012) 518-533.
 J. W. Fergus, Journal of Power Sources 195 (2010) 939-954.
 L. Yang, M. Takahashi, B. Wang, Electrochimica Acta 51 (2006) 3228-3234.
 M. Molenda, R. Dziembaj, D. Majda, M. Dudek, Solid State Ionics 176 (2005) 1705-1709.