Composite films of nanobeam V 2 O 5 and poly-3,4-ethylenedioxythiophene (PEDOT) were grown using an electrochemical polymerization method. PEDOT in the composite film connects the isolated V 2 O 5 nanobeams and gives rise to a conductive network, improved Li-ion accessibility and transport pathways in the electrode. The nanobeam-V 2 O 5 /PEDOT composite film cathodes have high capacities, excellent rate capabilities and cycling stabilities at various C rates: their specific capacities were 262 mAh g À1 at 0.1 C, 239 mAh g À1 at 1 C, 186 mAh g À1 at 10 C, and 141 mAh g À1 at 100 C. After testing the battery for more than 150 battery cycles at a rate of 10 C, the degradation rate was found to be approximately 9 %. The diffusion coefficient of the nanobeam-V 2 O 5 crystalline electrode was calculated to be approximately 4.6 10 À8 ; and those of a-, e-, and d-Li x V 2 O 5 crystalline phases, were estimated to be in the range of (2.1-9.8) 10À10 . Under the conditions of PEDOT coating and networking in the composite film, the diffusion coefficients of each phase of Li x V 2 O 5 that reversibly formed during the discharging and charging processes were able to be estimated.

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Composite films of nanocrystalline V 2 O 5 embedded in a conducting polymer, poly-3,4-ethylenedioxythiophene (PEDOT), were grown using an electrochemical polymerization method. The nanobeam-shaped V 2 O 5 and PEDOT composite film cathodes have high capacities, excellent rate capabilities and cycling stabilities: the specific capacity was 269 mAhg -1 and the degradation rate was only 8% after 100 consecutive cycles at 1 C rate. The charge transfer resistances (R ct ) for the nanobeam-V 2 O 5 /PEDOT composite film cathodes were smaller than that for the nanobeam-V 2 O 5 powder cathode, in the electrochemical impedance measurements. The diffusion coefficient (D Li+ ) in the nanobeam-V 2 O 5 crystallines was calculated to be approximately 4.6 x 10 -8 , and the values of D Li+ for each of α-, ε-, and δ-Li x V 2 O 5 crystalline phases, reversibly formed in the composite films during the discharging and charging processes, were able to be estimated in the range of (2.1~9.8) x 10 -10 .

Flexible composite films of nanobeam V2O5 and conductive polymer have been grown using the facile electrochemical polymerization method, which involves the application of anodic polymerization potential to the substrate electrode with the dispersed nanobeam V2O5 in solutions containing monomer - pyrrole or EDOT. For the case of pyrrole: V2O5 nanobeams can be thoroughly coated with polypyrrole, by taking advantage of the oxidative catalytic action of V2O5 in pyrrole polymerization. For the case of EDOT: since the advantage of V2O5 oxidative catalytic action is not applicable to PEDOT, it had been copolymerized with a surfactant p-TSA to achieve thorough and smooth coating of V2O5 nanobeams. Thus produced conductive polymers have shown to connect the isolated V2O5 nanobeam structures and provide valid electrical conductive networks for the cathode electrodes. These polymers enhanced the accessibility and diffusability of Li+ ions, thereby enabled V2O5/PPy and V2O5/PEDOT nanobeam composite film cathodes to have excellent cycling stability.