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Solid solutions of LiMn2−X−YTiXFeYO4 (X = 0.0 ⩽ X ⩾ 0.1, Y = 0.05) nanoparticles were synthesized by urea-glycerol combustion method. The undoped/doped LiMn2O4 nanoparticles were characterized by XRD, FT-IR, FE-SEM and electrochemical techniques. The LiMn2−X−YTiXFeYO4 spinel shows higher lattice constant of 8.279 A at X = 0.10 Ti doping, while the Ti and Fe dual doped exhibits a = 8.212 A. No obvious impurity phases/structural changes are observed in all the synthesized LiMn2−X−YTiXFeYO4 (X = 0.0 ⩽ X ⩾ 0.1, Y = 0.05) nanomaterials. The appearance of FT-IR band at ∼603 cm−1 evidenced the formation of Li–Ti–Mn–O bonds. Increased peak current is observed for the compound LiMn1.90Ti0.05Fe0.05O4 attributable to the improved Li+ diffusion caused by the reduced Rct values and path lengths. LiMn1.90Ti0.05Fe0.05O4 exhibits a very small increase of 73 Ω cm2 Rct value even after 100th cycle, while that of 1122 Ω cm2 for LiMn2O4. A high specific discharge capacity of 125 mA h g−1 is retained even after 100th cycle effected by presence of Ti & Fe in the Mn site. The LiMn1.90Ti0.05Fe0.05O4 nanoparticles sample exhibit decent capacity retention of 90% at 100th cycle, and it can be able to deliver higher and constant discharge capacity and it may be a good alternative for the existing cathode materials.

For the first time, solid solutions of LiMn2–X Mo X O4 nanoparticles were synthesized by combustion method at 700 °C in air. The synthesized LiMn2–X Mo X O4 (X = 0.0–0.2) nanoparticles were characterized by X-ray powder diffraction, Fourier transform infrared spectroscopy (FT-IR), Field emission-scanning electron microscopy, and Particle size analysis. The unit-cell constant is increasing from 8.237 to 8.293 A with the increase of Mo, the presence of Mo at X ≤ 0.05 in LiMn2–X Mo X O4 nanoparticles retained the spinel structure (Fd-3m), whereas on increasing the Mo (X ≥ 0.05 %), the ordering of Li+ ions in both octahedral and tetrahedral cationic position leads to the lowering of symmetry (P4132). On increasing the Mo content, prominent peak splitting and broadening are observed at 600–500 and 830 cm−1 for Li–Mn–O and Mo–O respectively in the FT-IR spectra. The TG/DTA spectrum reveals that the convenient formation of Li mangano-molybdate is at 700 °C. The voltammograms of all the samples show two redox peaks centered around 4 V except for the sample with higher Mo doping (X = 0.2). The sample with X = 0.03 shows higher redox peak current values. A marginal increase of 146 Ω R ct value was found for the LiMn1.97Mo0.03O4 nanomaterial after 10th cycle which is rather high for the rest of the materials. A discharge capacity retention of 88 % at 50th cycle is observed for X = 0.03 sample, while the other samples exhibit drastically reduced capacity. The LiMn1.97Mo0.03O4 nanoparticle can able to deliver higher and constant discharge capacity, and it may be a good alternative for the existing cathode materials.

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