Synthesis and electrochemical performances of LiV3O8/poly (3, 4-ethylenedioxythiophene) composites as cathode materials for rechargeable lithium batteries

LiV3O8/poly (3, 4-ethylenedioxythiophene) (LVO/PEDOT) composites were synthesized via an in-situ oxidative polymerization process. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, galvanostatic discharge/charge tests, and electrochemical impedance spectroscopy techniques are used to characterize the as-prepared samples. The results demonstrated that the electrochemical performances of LVO/PEDOT composites have greatly improved in comparison with bare LVO. The discharge capacities of 20 wt% LVO/PEDOT composite are 270, 265, 252, 240, and 229 mAh g(-1) and > 95% capacity retention is maintained after the charge-discharge 50 cycles at the current densities of 60, 90, 120, 180, and 240 mA g(-1), respectively. A high reversible capacity of 176 mAh g(-1) (only 58 mAh g(-1) for the bare LVO) can be maintained after 50 cycles at a very high current rate of 2000 mA g(-1). Electrochemical impedance spectra results implied that the 20 wt% LVO/PEDOT composite revealed a decreased charge transfer resistance and increased Li+ ions diffusion ability. This noteworthy improvement is ascribed to the combination of PEDOT, which can act just as a defending layer to inhibit the LVO from direct contact with electrolyte and buffer volume change, and act just as a conductive network to improve the electronic conductivity, thus cycling stability and rate capability are improved.