Study On The Dielectric Properties Of PU/CuPc Composite As A Novel Energy Storage Material

Dielectric elastomer (DE) is subject to a voltage through its thickness, it will enlarge in thickness and expand in area. After removing voltage, it will return to the original size rapidly. It has many advantages such as light weight, rapid response, high energy density and low cost. Dielectric elastomer is especially suitable for low frequency and large deformation electricity generation.In our subject, polyurethane foam (PU) is compressed under compression, the thickness becomes thinner with increasing pressure but the surface maintains constant. CuPc oligomer was synthesized using solution method. Then CuPc was added into the void of PU foam to prepare PU/CuPc dielectric composite using physical method. SEM indicated that the continuous fibrils forming of PU foam with a number of voids were covered by CuPc perfectly at the225wt%CuPc content.The frequency dependence of complex impedance (Z*), complex permittivity (ε*) and complex modulus (M*) as well as the Cole-Cole plots for Z*and M*were done for two specimens:1) a CuPc film prepared by loading high pressure to CuPc grains and2) the PU/CuPc composite. The theoretical analysis was done by using a series combination of CPE circuit models. Results indicated that there were three relaxation types of CuPc, for example, interfacial polarization between CuPc film and electrodes, grain boundary effect, bulk effect. The high complex permittivity of the CuPc film at low frequency was attributed to the movement of highly polarized polarons in addition to interference polarization between the electrode and CuPc. On the other hand, the dielectric effect of CuPc grain was indistinct. The bulk and grain boundary components of CuPc didn’t effect the Cole-Cole plots of the PU/CuPc composite. There were only interfacial polarizations in composite, that is, the approximation of PU fibrils coated by CuPc and composite/electrode interface. The boundary effect of CuPc grains by the contact of CuPc coated on PU fibrils became predominant with increasing pressure.Finally, charge and discharge under different pressures were measured for PU/CuPc composite. And results indicated that the dielectric materials with high elasticity provide the possibility of the conversion from natural mechanical energy to electric energy.