Cycling behavior of selenium-doped LiMn2O4 spinel cathode material at 3 V for lithium secondary batteries

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 3 V range. Selenium-doped LiMn2O4 (LiSe0.1Mn1.9O4 and LiSe0.4Mn1.6O4) delivers 98 and 105 mAh g−1, respectively, at a current density of 0.2 mA cm−2 in the voltage range of 2.4–3.5 V, without the capacity loss typically seen with unmodified spinel material in the 3 V 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.