Selenium-doped LiMn2O4 spinel cathode is synthesized by a sol–gel method. In spite of the observed Jahn–Teller phase transformation, the cathode exhibits a gradual gain in capacity when cycled in the 3V range. Selenium-doped LiMn2O4 (LiSe0.1Mn1.9O4 and LiSe0.4Mn1.6O4) delivers 98 and 105mAhg−1, respectively, at a current density of 0.2mAcm−2 in the voltage range of 2.4–3.5V, without the capacity loss typically seen with unmodified spinel material in the 3V range. Although, the exact mechanism for such capacity enhancement is not clear, it is proposed that the particle size and the structural distortion of the prepared powder may play a significant role in negating the volume change involved with Jahn–Teller phase transformation during cycling.