Overcoming Jahn-Teller distortion for spinel Mn phase

A new sulfur-doped spinel material, LiAl0.24Mn1.76O3.98S0.02 with a submicr on and well-developed octahedral structure was synthesized by a sol-gel met hod using glycolic acid as a chelating agent. The structural integrity of t he oxysulfide material before and after the charge-discharge cycling was me asured by X-ray diffraction and high-resolution transmission electron micro scopy. Our as-synthesized material overcomes the Jahn-Teller distortion in all operating voltage regions. It exhibits capacities of 103, 128, and 230 mAh/g in the 4 V (4.4-3.0 V), 3 V (2.4-3.5 V), and both the 3 and 4 V regio ns (4.4-2.4 V), respectively, with excellent cyclability. (C) 1999 The Elec trochemical Society. S1099-0062(99)08-114-6. All rights reserved.