Effects of V doping on the electrochemical performance of Li3MnO4 for lithium ion batteries

Li3Mn1 − xVxO4 (0 ≤ x ≤ 0.4) cathode materials were synthesized by the solid state method. The effect of the vanadium content on the structure, morphology and electrochemical properties of the samples was investigated. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical measurements, respectively. The XRD patterns indicated that the doped samples showed similar phase structure with un-doped samples and the peaks of doped samples slightly shift towards a lower diffraction angle with increasing of vanadium content. The vanadium doping could reduce particle aggregation of Li3Mn1 − xVxO4 samples. The Li3Mn1 − xVxO4 (0 < x ≤ 0.3) samples showed higher reversible capacity and better rate-capability compared to Li3MnO4. Electro-chemical impedance spectroscopy (EIS) measurements revealed that the improved electrochemical performances could be attributed to the lower solid electrolyte interfacial resistance and charge-transfer resistance due to appropriate amount of vanadium doping in Li3MnO4.