Magnesium substitution to improve the electrochemical performance of layered Li2MnO3 positive-electrode material

Abstract Li 2 MnO 3 has received lots of attention due to its large theoretical capacity. However, its application is obstructed by low practical capacity and poor cycling stability. Here, a new tactic of magnesium substitution for partial lithium to improve the electrochemical performance of Li 2 MnO 3 by a traditional solid state reaction is presented. Sample with only 1% magnesium content delivers a large initial discharge capacity of 307.5 mAh g −1 which is much superior than the 241.9 mAh g −1 of pristine Li 2 MnO 3 . The cycling performance also get improved that the capacity retention is 84.5% for Li 1.98 Mg 0.01 MnO 3 but only 77.7% for pristine counterpart after 30 cycles at 0.1 C. Moreover, the effective suppression of voltage decay has been achieved because of improved kinetic properties and leads to a tremendous progress in the energy density which is as much as 944 Wh kg −1 for Li 1.98 Mg 0.01 MnO 3 compared with 747.1 Wh kg −1 of Li 2 MnO 3 . These achievements attained by Mg-doping make Li 2 MnO 3 a promising positive-electrode material for the next generation of lithium ion batteries.