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Li3V2(PO4)3/Li3PO4 (LVPO/LPO) composites as cathodes for Li-ion batteries were synthesized by the hydrothermal method and subsequently annealed in an Ar atmosphere. The effect of Li3PO4 content on the crystal structure, morphology and the related magnetic and electrochemical properties of Li3V2(PO4)3/Li3PO4 composites, containing 7.5 wt% and 14 wt% of Li3PO4 (LVPO/LPO-7.5 and LVPO/LPO-14) was investigated. The microstructure and morphology of the obtained composites were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM); magnetic and electrochemical properties investigations were performed using the electron spin resonance and galvanostatic methods, respectively. It was shown that Li3V2(PO4)3/Li3PO4 composites exhibit a high discharge capacity, good cycle performance (105 and 120 mAh g−1 for the 200th cycle at 1C for LVPO/LPO-7.5 and LVPO/LPO-14, respectively), and insignificant changes in the surface morphology after 200 lithiation/delithiation cycles. Our results demonstrate that the increase in Li3PO4 content led to a decrease in the Li stoichiometry and magnetic inhomogeneity in Li3V2(PO4)3 phase; thus, the improvement in the electrochemical performance of LVPO/LPO composites due to incorporation of Li3PO4 can be attributed to their chemical and magnetic inhomogeneity.

Here, we present the investigation of the magnetic properties of Li3V2(PO4)3/Li3PO4 composites, which can be potentially used as a cathode material in lithium-ion batteries. Li3V2(PO4)3/Li3PO4 was synthesized by the thermal hydrolysis method and has a granular mesoporous structure. Magnetic properties of the composite were investigated using magnetometry and electron spin resonance methods. Based on magnetization measurements, the simultaneous existence of the paramagnetic phase with antiferromagnetic interactions between spins of V3+ ions and magnetically correlated regions was suggested. Most probably, magnetically correlated regions were formed due to anti-site defects and the presence of V4+ ions that was directly confirmed by electron spin resonance measurements.

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