Controllable synthesis of spherical Li3V2(PO4)3/C cathode material and its electrochemical performance

Spherical Li3V2(PO4)(3)/C (LVP/C) composites are successfully synthesized via two different spray-drying processes. XRD results reveal that some impurities, such as Na3V2(PO4)(3), Li2NaV2(PO4)(3) and Li-4(P2O7), appear when sodium salt of carboxy methyl cellulose (CMC) acts as carbon source. SEM images show two different morphologies: solid spherical particles for LVP/C(A) prepared by adding CMC after pre-sintering, and hollow for LVP/C(B) prepared by adding CMC before pre-sintering. Compared to LVP/C(B), LVP(A) presents higher tap density and better electrochemical performance at any C-rate. Remarkably, another charge/discharge plateaus or anodic/cathodic peaks around 3.85 V are detected for both LVP/C(A) and LVP/C(B) electrodes, which is attributed to the formation of Li3-xNaxV2(PO4)(3) or some other electrochemically active composites containing Na+. CMC addition sequence has a significant influence on morphology of Li3V2(PO4)(3). Furthermore, acting as carbon source and Na dopant, CMC shows a notable effect on electrochemical behavior of Li3V2(PO4)(3) cathode material. (C) 2012 Elsevier Ltd. All rights reserved.