High energy density secondary batteries have received broad attention owning to their importance for a
large variety of applications ranging from portable electronics to electric vehicles. Here we present a high
energy density and low-temperature stable composite cathode consisting of Li3V2(PO4)3 particles and
reduced graphene oxide (rGO) prepared through a graphene hydrogel assisted approach. The
Li3V2(PO4)3/rGO cathodes exhibit a stable capacity of about 101 mAh g1 after 500 cycles over a potential
window of 4.3e3.0 V (extrapolated to energy density of 374Wh kg1 versus carbon anode). In particular,
the composites show much enhanced capacity retention of about 80% at a temperature of 5 C,
compared to the pristine Li3V2(PO4)3 with a retention lower than 70%, which is ascribed to the improved
electric conductivity confirmed by I-V analysis, the stable rGO coating demonstrated by the post-cycled
composite characterization, and density functional theory calculation. The composite design presented
here is expected to be applicable for many other possible anodes and cathodes.