Synthesis and electrochemical characterization of multi-cations doped spinel LiMn₂O₄ used for lithium ion batteries

Homogeneous substitution of Cu(II), Al(III) and Ti(IV) for Mn in the spinel Li[Mn₂]O₄ is synthesized by lactic-acid assisted Pechini method. Galvanostatic charge-discharge between 3.5 and 4.3 V (versus Li ⁺/Li) at C/2 rate shows that the multi-cations doped spinel exhibits initial discharge capacity of 134 mAh g^-1 with a 97% capacity retention after 400 cycles at room temperature. When cycling at 55 °C, the doped sample shows 91% capacity retention after 50 cycles compared to 70% retention for the undoped sample. As the charge-discharge rate increases to 12C, the doped sample delivers capacity of 111 mAh g^-1, which is much higher than that of the undoped sample of only 84 mAh g^-1. Moreover, as the charge-discharge rate returns from 12C to C/2, the discharge capacity of the doped electrode recovers nearly completely while the undoped sample lost more than 7% of its capacity.