Effect of Ti-doping on Electrochemical Activity of Li0.44MnO2 Cathode Material for Li-ion Batteries

Abstract

Manganese-based oxides can work as economic cathode materials for Li-ion batteries. Various metastable manganese oxides can exhibit efficient Li⁺ (de)insertion activity. One such system is chemically derived Li_0.44MnO₂ offering reversible Li⁺ intercalation involving Mn⁴⁺/Mn³⁺ redox reaction albeit with poor rate kinetics. In this work, the electrochemical activity of tunnel-structured Li_0.44MnO₂ has been enhanced by tailoring its crystal structure and particle morphology by Ti-doping into Mn sites. X-ray diffraction and spectroscopy analyses revealed successful Ti-doping while retaining the original structure. Varied degree of Ti-doping was found to exhibit improved electrochemical performance, with the Li_0.44Mn_0.89Ti_0.11O₂ delivering the highest capacity of 129 mAh g^-1 at a rate of C/20. Ti-doping was further found to improve the Li⁺ diffusivity and rate kinetics. This enhancement in electrochemical activity can be ascribed to the combined effect of Ti-induced lattice expansion and decrease in particle size. Electrochemical titration and ex situ analyses revealed the occurrence of single-phase (solid-solution) redox mechanism. Ti-doped Li_0.44MnO₂ can be harnessed as an economic cathode for Li-ion batteries.