Electrochemical behavior of Li_(3-x)M'_xV_(2-y)(PO_4)_3 (M' = K, M' = Sc, Mg + Ti)/C composite cathode material for lithium-ion batteries

摘要

Composites of monoclinic Li_(3-x)M'_xV_(2-y)(PO_4)_3 (M' = K, M" = Sc, Mg + Ti) with carbon were synthesized by solid-state reaction using oxalic acid or 6% H_2/Ar gas mixture as reducing agents at sintering temperature of 850 ℃. The samples were characterized by X-ray diffraction (XRD), voltammetry and electrochemical galvanostatic cycling. The capacity of Li_3V_2(PO_4)_3 synthesized using hydrogen as the reducing agent was 127 mA tig~(-1) and decreased to 120mAhg~(-1) after 20 charge-discharge cycles. The substitution of lithium and vanadium for other ions did not result in the improvement of the electrochemical characteristics of the samples.