Sodium Citrate Induced Sol-gel Synthesis of Rhombohedral Structure Li₂NaV₂(PO₄)₃/C Composite with High Capacity and Stability as Cathode for Lithium–ion Batteries

Abstract

The rhombohedral structure Li₂NaV₂(PO₄)₃/C composites were successfully synthesized by a sodium citrate induced sol-gel method. The Li₂NaV₂(PO₄)₃/C consists of microplates roughly 80–90 nm in thin. The carbon content in the LNVP/C is approximately 8.29 wt%. As cathode materials for lithium-ion batteries, a cathodic peak at 3.67 V and an anodic peak at 3.82 V can be seen in CV curves, corresponding to the redox couple of V⁴⁺/V³⁺. In addition, the electrode can deliver an initial discharge capacity of 111.4 mAh g⁻¹ at 1 C and about 96.4% of the initial capacity is maintained after 150 cycles. LNVP/C also exhibits high coulomb efficiency and good rate performance.