Layered Li[LixNi(1 -3x)/2Mn(1 + x)/2]O-2 materials with x = 0.05, 0.1, 0.15, and 0.2 were synthesized using a sol-gel method. The layered Li[LixNi(1-3x)/2Mn(1+x)/2]O2 structure was stabilized by a solid solution between LiNiO2 and Li2MnO3. The discharge capacity of the Li[LixNi(1 -3x)/2Mn(1+ x)/2]O-2 electrodes increased with decreasing Ni content. Li[LixNi(1 -3x)/2Mn(1 + x)/2]O-2 electrode with x = 0.05,01,015, and 0.2 delivered high discharge capacities of 184, 193, 206, and 209 mAh g(-1) at 30 degreesC, respectively, with excellent cycleability. (C) 2003 Elsevier Science B.V. All rights reserved.