Structural, electrical and electrochemical studies of LiNi0.4M0.1Mn1.5O4 (M = Co, Mg) solid solutions for lithium ion battery

Abstract

The LiNi0.4M0.1Mn1.5O4 (M = Co, Mg) solid solutions are synthesized by citric acid assisted sol-gel method and characterized by using TG/DTA, XRD, FTIR, EPR and SEM. The electrochemical characterization is carried out using CR-2032 coin type cell configuration. The cyclic voltammogram shows two pairs of redox current peaks, 4.35/3.80V and 4.90/4.37V vs. Li in a typical case of Co-doped sample, ascribed to two-step reversible intercalation of Li. A.c.-impedance (Nyquist plot) shows high frequency semicircle and a sloping line in the lowfrequency region. The semicircle is ascribed to Li-ion migration through interface from the surface layer of the particles to electrolyte. The LiNi0.4Co0.1Mn1.5O4 shows reasonably good capacity retention in 20 cycles of galvanostatic charge/discharge cycling.