Processing of hybrid shape memory alloy coupled with P(VDF-TrFE) piezoelectric polymer composite for energy harvesting application

Abstract

Small-scale energy harvesting to power self-powered electronic devices is tremendously increasing. In this context, the ability to combine thermal and mechanical energy harvesting using smart materials deserves more attention for further study. We have presented the feasibility of using P(VDF-TrFE) piezoelectric polymer coupled with NiTi shape memory alloy (SMA) to harvest both mechanical and thermal energy in simple scalable devices. A novel hybrid composite consisting of SMA, and P(VDF-TrFE) has been developed without any complex composites or patterned structures, which couples the piezoelectric effect of the poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) and the shape memory effects of NiTi SMA. We have also fabricated a multi-layer SMA/PEN/P(VDF-TrFE) device using epoxy as an interface and bonding layer. During bending, the P(VDF-TrFE) device with an active area of 3.68 cm2 generated an output voltage of 8 V and an output power of 6.25 µW. When coupled with NiTi SMA to create a hybrid composite thermoelectric material, the device can convert the phase change associated with SMA, and thus thermal energy is converted to mechanical energy and finally into electrical energy. The SMA/P(VDF-TrFE) hybrid composite produced an output voltage of ∼2 V for one cyclic heating and cooling of the device. This is a promising approach for the further development of coupled hybrid energy harvester devices for the powering of small-scale electronic devices such as sensors, MEMS, or biomedical devices.

Optimizing Piezoelectric Coefficient in PVDF Fibers: Key Strategies for Energy Harvesting and Smart Textiles

“…Therefore, the d 33 cannot be expected to be as high as for typically spin-coated or casted PVDF films. [24,76] From our study, using DMAc as a solvent and adding rGO as filler is the most promising strategy for electrospun PVDF mats to obtain high efficiency in energy harvesting or sensing applications. Notably, the highest conductivity of DMAc (0.300 ± 0.013 μScm −1 ) over DMF (0.241± 0.013 μScm −1 ) and just 1% addition of rGO is able to increase the 𝛽 phase fraction over standard PVDF by 9%.…”

“…The device can convert the finger tapping motion (mechanical movements) into electricity by repeated pressing and releasing movements. [ 24 ] By finger tapping, we change the polarization of the PVDF, and a piezoelectric potential is developed between the two electrodes. Simply, the potential difference is causing the transitory passing of the free electrons from one electrode to another, leading to a positive voltage peak.…”

“…The instant release of stress caused by the finger press, a negative output voltage appears owing to the decrease in the piezo potential and discharging of the accrued electrons. [ 24 ] From Figure 6a,b, PVDF/DMAc‐rGO showed a higher output voltage (6 ± 1.4 V) than pure PVDF/DMAc (3.4 ±1 V). Similarly, the current signals exhibited more than double the output value of 320 ± 81 nA from the PVDF/DMAc‐rGO (Figure 6d).…”

“…Therefore, the d 33 cannot be expected to be as high as for typically spin‐coated or casted PVDF films. [ 24,76 ]…”

“…[ 23 ] An external polarization process or mechanical stretching increases PVDF's polar β phase content. [ 24 ] Nevertheless, the polarization at a high electric field can cause electrical breakdown and structural damage. [ 25 ] In this context, electrospinning is considered a facile and efficient technique for producing self‐poled PVDF nano/microfibers.…”