An alginic acid assisted rheological phase synthesis of carbon coated Li3V2(PO4)3 with high-rate performance

A nanoscaled Li3V2(PO4)3/C(LVP/C) composite is successfully synthesized via a modified rheological phase method. Alginic acid is applied as a new carbon source and ethylene glycol is used as the dispersant, and both of which play multifaceted roles during the synthetic route. A series of intensive investigations shows that the LVP/C composite possesses a three-dimensional carbon network and a loose structure, which provide discontinuous electronic and ionic pathways. The electrochemical performance of the LVP/C cathode is revealed to be impressive in terms of capacity, high-rate capability and long-life cycleability. Between 3.0 and 4.3 V, it delivers a discharge capacity of 132.3 mAh g−1 at 0.5 C rate, approaching the theoretical value, and can cycle at a rate as high as 40 C without obvious capacity fading. Most distinctively, when discharged at 90 C ultrahigh rate (charged at 5 C rate), the largest capacity of 61.4 mAh g−1 can still be available, after 600 cycles the capacity retention can still maintain 76%. When operated within 3.0-4.8 V, it cannot only discharge the initial capacity of 184.1 mAh g−1 at 0.1 C, but also exhibit a stable cycling performance at 20 C for 400 cycles. These excellent performances can be fundamentally attributed to the high electronic/ionic conductivities which are related closely to the modified rheological phase preparation route and the promising new carbon source.