Improving the cycle stability of LiCoPO4 nanocomposites as 4.8 V cathode: Stepwise or synchronous surface coating and Mn substitution

• Structural, morphological and electrochemical effects of Mn doped LiCo1 − xMnxPO4–C electrodes are investigated.
• Cheap, effective and simple sol-gel assisted carbothermal reduction approach is used.
• After 60th cycle, capacity retention is almost 92% for LiCo0·95Mn0.05PO4–C electrode.
• Mn-doped sample exhibits distinctive oxidation (4.76 V and 4.12 V) peaks.

Nanostructured LiCo1 − xMnxPO4/C (x = 0 and 0.05) materials were successfully produced as superior quality cathodes by combined sol-gel and carbothermal reduction methods. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopy (EDS), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma (ICP), cyclic voltammetry (CV) and galvanostatic measurements were applied to determine the phase purity, morphology and electrochemical qualifications. HR-TEM analysis reveals that the thickness of the surface carbon layer of 5 to 10 nm range with the uniform distribution. LiCo0·95Mn0·05PO4/C particles were between 40 and 80 nm and the same material exhibits a higher and stable reversible capacity (140 mA h g− 1) with the long voltage plateau (4.76 V). Substitution of Co2 + with Mn2 + in LiCoPO4/C has an influence on the initial discharge capacity and excellent cycling behaviour. The obtained results have attributed that production dynamics in nano-synthesis, the coating process with proper carbon source and an effective doping represent three parameters to prepare favorable cathode materials.

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