Solid State Ionics 127 (2000) 31–42 www.elsevier.com / locate / ssi Electrochemical characterization of commercial lithium manganese oxide powders a, a a a b a * H. Huang , C.H. Chen , R.C. Perego , E.M. Kelder , L. Chen , J. Schoonman , c c W.J. Weydanz , D.W. Nielsen a Delft Interfaculty Research Center, Renewable Energy, Laboratory for Inorganic Chemistry, Delft University of Technology, Julianalaan 136, 2628BL Delft, The Netherlands b Laboratory for Solid State Ionics, Institute of Physics, Chinese Academy of Sciences, Beijing 100080, China c GAIA Akkulatorenwerke GmbH, P .O. Box 100616, 99726 Nordhausen, Germany Received 5 February 1999; accepted 10 February 1999 Abstract Five commercial lithium manganese oxide powders have been studied. The XRD spectra showed all samples to exhibit the spinel structure. The composition and morphology were analyzed by Jaeger–Vetter titration and scanning electron microscopy. The lithium intercalation / de-intercalation characteristics and the cycleability have been studied using state-of- the-art cells. The morphology of the particles and crystallites, as well as the defect structure of the spinel, were found to play an important role in the capacity retention during electrochemical cycling. The capacity corresponding to the 4.1 V phase transformation process faded faster than that of the 4.0 V single-phase transition during cycling, which enhanced lower plateau capacity fading and higher voltage polarization. The cycleability at the 3.0 V region has also been studied and indicated that the typical spinel lithium manganese oxide is not suitable to be cycled in the 3.0 V region. Therefore, it will be deleterious to overdischarge the spinel materials.  2000 Elsevier Science B.V. All rights reserved. Keywords: Li–Mn–O powders; Spinel structure; Cycleability; Morphology; Defect structure 1. Introduction fabricate a spinel electrode material with an exact, predetermined composition. Another hindrance for The spinel LiMn O is an attractive cathode its application is its large capacity fading, especially 2 4 material for commercial lithium ion batteries, be- when the cells are operated at 558C. The capacity cause of its low-cost and lower toxicity compared loss is ascribed to several possible factors: (1) an with the layered oxides LiCoO and LiNiO [1–3]. electrochemical decomposition of the electrolyte 2 2 For the consideration of practical application, it is solution; (2) a slow dissolution of Mn from the important to produce LiMn O powders with excel- active cathode into the electrolyte; (3) the Jahn– 2 4 lent capacity and cycleability. Unfortunately, there Teller effect resulting in the phase degradation, exists a wide range of solid solutions in the Li–Mn– especially in deeply discharged LiMn O . Many 2 4 O spinel system [4], which makes it difficult to researchers have reported a solution to the indicated problems in order to improve the characteristics of *Corresponding author. the manganese spinel material [5–10]. 0167-2738 / 00 / $ – see front matter  2000 Elsevier Science B.V. All rights reserved. PII: S0167-2738(99)00057-0