Novel “3-D spacer” all fibre piezoelectric textiles for energy harvesting applications

Abstract

Using “3D-spacer” technology, we have knitted 80% β-phase PVDF with Ag/PA66 fibres to demonstrate all fibre piezoelectric power generators. The 3D structure provides a power density of 1.10–5.10 μW cm−2 at applied impacts of 0.02–0.10 MPa.

Exclusive self-aligned β-phase PVDF films with abnormal piezoelectric coefficient prepared via phase inversion

“…The d33 values increases with the decrease in quenching temperature, reaching ~49.6 pm/V, much higher than the typical values of -20~-35 pm/V of commercial products and those obtained by mechanical stretching and subsequent poling. [3,6,20,33] These values are also comparable to the PVDF nanofibres which show a d33 coefficient of -54 pm/V, which originates from the extraordinarily high -phase with ~75% crystallinity. [25] This abnormally high piezoelectric coefficient from the films quenched at -20ºC is attributed to the exclusive (~100%) -phase content, extremely high crystallinity of 56% and / ratio of 45.…”

“…The topography of the PVDF films shows spherical structures, which are representative of a crystallisation-dominated precipitation, wherein all the crystalline particles are nucleated in a similar concentration field and fused together to form a bicontinuous structure. [17] The surface roughness is of the order of ~150 nm and did not vary [3,6,20,33] These values are also comparable to the PVDF nanofibres which…”

“…Moreover, the β-phase crystals are randomly oriented in these PVDF films and show no specific directional preference. Polarization under high electric field, [6,20] by Corona poling, [12] or by mechanical stretching [3,6,15] is subsequently carried out to obtain electroactive PVDF films. These operations need to be done at elevated temperatures (>80 o C), requiring high voltage equipment and films with dense structure and high β-phase content.…”

“…[1][2][3][4] These properties stem from its unique polymorphism which also gives rise to its extraordinary mechanical properties, high chemical resistance, good thermal stability and biocompatibility. [5] PVDF shows four significant crystalline phases α, β, δ and γ; [2,6] with the electroactive β-phase being utilized most frequently for the development of sensors, actuators [7,8] and microgenerators. [4,9,10] Owing to its importance, the formation of electroactive β crystalline phase has been intensively investigated through various routes, including melt casting, [15] solution deposition, [11] spin coating [12] and phase inversion.…”

A record flexible piezoelectric KNN ultrafine-grained nanopowder-based nanogenerator

“…[12][13][14] Furthermore, huge progress has been made in the piezoelectric field by Prof. Zhong Lin Wang's group up to now, 15,16 and other groups also make great progress. [17][18][19] To achieve higher output voltage and current, some researchers turn to traditional triboelectric ways, [20][21][22] while others switch to the way of the combination the piezoelectric and triboelectric together. 23 It is necessary to explore a kind of device which can not only generate high output voltage and current but also be of quite good flexibility.…”