Articles written in Bulletin of Materials Science
Volume 23 Issue 5 October 2000 pp 345-348
Solid solutions of compositions LiNi
Volume 24 Issue 1 February 2001 pp 51-55 Electrode Materials
Spinel lithium manganese oxide, LiMn2O4, is beset with problems of capacity fade upon repeated cycling. The loss in capacity upon cycling is attributable to Jahn–Teller distortion and manganese dissolution in the electrolyte in the charged state. One way to circumvent this capacity fade is to introduce other 3𝑑 transition metal ions in the LiMn2O4 lattice. In this paper, we report on the effect of partial substitution of manganese in the LiMn2O4 phase with copper (II) and chromium (III) ions. It has been shown that the higher octahedral stabilization energy of trivalent chromium imparts greater structural stability to chromium-doped LiMn2O4 spinels. Both copper and chromium reduce the capacity of the spinel in the 4 V region. In terms of its good reversible capacity and ability to sustain cycling with minimal capacity fade, LiCr0.1Mn1.9O4 may be considered as a potential cathode material for lithium rechargeable cells.
Volume 37 Issue 3 May 2014 pp 705-711
In order to improve the cycling performance of LiMn2O4 based cathode materials, we have synthesized a new composition, LiNi0.4M0.1Mn1.5O4 (𝑀 = Al, Bi), by the sol–gel method. The formation of solid solutions is confirmed by structural characterization using TG/DTA, XRD, FT–IR, EPR, SEM and EPR. A.c.-impedance (Nyquist plot) showed a high frequency semicircle and a sloping line in the low-frequency region. The semicircle is ascribed to the Li-ion migration through the interface from the surface layer of the particles to the electrolyte. Cyclic voltammogram (between 3.5 and 4.9 V) for these materials using CR2032 coin-type cell shows two pairs of redox peaks corresponding to two-step reversible intercalation process, wherein Li-ions occupy two different tetragonal 8a sites in spinel Li𝑥Mn2O4 (𝑥 < 1) lattice. The galvanostatic charge/discharge curves for 𝑀 = Al (77 mAh g-1) showed reasonably good capacity retention than that of 𝑀 = Bi (11 mAh g-1) at the end of 17th cycle.
Volume 42 | Issue 5