Energy harvesting with polymers, ferroelectrets and piezocomposites

Prof. Chris Bowen

Department of Mechanical Engineering

University of Bath

Future Smart Applications for Elastomers

27 March IoM3

Ferroelectric Materials

• Below the Curie temperate (Tc) the

crystal structure distorts to tetragonal

structure.

• Zr4+ or Ti4+ ion displaced from the

centre, creating an electric dipole.

Cubic and

Symmetrical

(above Curie T)

Tetragonal and

non-symmetrical

(below Curie T)

O2-

Pb2+

Ti4+, Zr4+

Ferroelectrics

Tetragonal Rhombohedral

6 polarisation directions

8 polarisation directions

Ferroelectric polymers:

Poly(vinylidene fluoride)

http://www.physics.montana.edu/eam/polymers/images/Piezoe5.jpg

Poling – achieving piezo response

This ‘freezes in’ the alignment of the domains, resulting in a net polarisation.

Dipoles are orientated within domains.

Dipoles randomly orientated.

To achieve net polarisation apply a high electric field at elevated temperatures.

Cool to room temperature (with the electric field still applied).

• Electric field parallel to the poling direction (polar axis) extends the material.

• Electric field opposite to the polar axis results in contraction.

• This is the actuator mode of operation.

• Strains are small ~0.1-0.3%

• PVDF even smaller – also low force (low stiffness)

Converse Piezoelectric Effect

Extension Contraction

0

500

1000

1500

2000

2500

3000

3500

-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0

Electric Field (kVmm-1

)

Str

ain

(p

pm

)

Extracted fibre

response

Direct Piezoelectric Effect

• Tensile or compressive force parallel to the poling direction (polar axis)

generates a potential difference across opposing faces.

• This is the sensing/generator mode of operation.

d33 ~ 2 x d31

Charge per unit force

PZT 300-600 pC/NPVDF 20-30pC/N

gij = dij/ permittivity

electric field per unit stress

PZT permittivity > 1000PVDF permittivity ~ 10

Generator modes

Applications

Novel Energy Materials: Engineering Science and Integrated Systems (NEMESIS) Grant agreement no.: 320963

@BowenNEMESIS

Peter Harris

Dan Zabek

E. Le Boulbar

Vaia Adamki

James Roscow

Andrew Avent

Oliver Weber

Vibration harvesting applications

TPMS

Motivation

IDTechEx Energy harvesting journal, Sept 2010

Energy Harvesting

• Inertial energy harvesting: relies on the resistance to acceleration of a mass.

Base movement sets up a vibration in a mass-spring system, from which electrical

energy can be extracted. Vibration amplitude at resonance can be significantly

larger than the amplitude of the base movement.

• Kinematic energy harvesting directly couples the energy harvester to the relative

movement of different parts of the source.

Examples include bending of a tyre wall to monitor type pressure, or the flexing and

extension of limbs to power mobile communications. Do not rely on inertia or

resonance. Since the strain in the harvester is directly coupled to a flexing or

extension of the source, they are connected at more than one point.

Intertial - Resonant Energy Harvesters

Linear: Works at specific frequency

BUT: Ambient vibrations can exhibit:

(i) multiple time-dependent frequencies(ii) may change with time(iii) can include components at relatively low frequencies

Bistable piezo-actuaton

State B

State A

State I

State II

Idea: Schultz/Hyer

Intertial – Bistable CRFP Laminate Energy Harvesters

• Bistable systems have broadband

energy harvesting characteristics due to

nonlinearity (e.g. cantilever beam in a

magnetic field)

Why CFRP laminates? (i) no stray

magnetic fields; small volume (ii) laminate

combined with piezoelectric materials (iii)

tailor laminate lay-up, elastic properties

and geometry.

Arrieta, Inman APL 2012

Bistable harvesting – the energy landscape

Harne et al. Smart Mater. Struct. 22 (2013) 023001

x,y curvature-energy map for bistable

Bistable vs. linear harvesters(Peter Harris)

[90/0/0/90]T Linear

[90/90/0/0]T Bistable

Linear lay-up [90/0/0/90]T

FWHM @1g 0.8Hz, Peak power 0.74mWFWHM @6g 1.8Hz, Peak power 12.8mW

Bistable lay-up [90/90/0/0]T

FWHM @1g 1.6Hz, Peak power 7.3mWFWHM @6g 8.2Hz, Peak power 12.8mW

Rotation and embedding

PZT (200mm) fibre/electrode/insulator in [0/90]T

Image courtesy of Mustafa ArafaAssociate Professor, American

University in Cairo

Kinematic - Bonded Devices

Battery-and wire-less tire pressure measurement systems (TPMS) sensor Noaman Makki • Remon Pop-Iliev , Microsyst Technol (2012) 18:1201–1212

Kinematic - Bonded devices

Smart Mater. Struct. 21 (2012) 015011, Direct strain energy harvesting in automobile tires using piezoelectric PZT–

polymer composites , D A van den Ende et al.

Development of a piezoelectric energy harvesting system for implementing wireless sensors on the tires

Lee et al. Energy Conversion and Management 78 (2014) 32–38

1.4μW/mm3

Electro-active polymers

Comparison of electroactive polymers for energy scavenging applications Smart Mater. Struct. 19 (2010) 085012

C Jean-Mistral S Basrour and J-J Chaillout

Polypower Energy Scavenger, 2013 Int Conf. Circuits, Power and Comp. Tech

EAP tyre patents

Ferroelectrets: Cellular non-polar piezoelectric polymers

PTFE

PTFE

FEP

45mm

45mm

Metal mesh

Force

Force

Metal mesh

d33 100-500pC/N d33 (PVDF) <20pC/N d33 (PZT) ~ 500pC/N

A A

Grounded Grid

PTFE

Corona Point

Metal reference

plateSample

Conducting

substrate

M. Gerard, C. R. Bowen, F. H. Osman, Processing and Properties of PTFE-FEP-PTFE Ferroelectret Films,Ferroelectrics, 422:59–64, 2011

Tribo-electric generators

Single-Electrode-Based Rotating Triboelectric Nanogenerator for Harvesting Energy from Tires Hulin Zhang, Ya Yang,Xiandai Zhong, Yuanjie Su, Yusheng Zhou, Chenguo Hu, and Zhong Lin Wang

ACS Nano, 2014, 8 (1), pp 680–689

Pyroelectric harvesting

• Thermoelectric – harvesting

temperature gradients

• Pyroelectrics – harvesting

temperature fluctuations

Sidney Lang, Physics Today.

Micro-patterning of PVDF (Daniel Zabek)

D Zabek, J Taylor, EL Boulbar, CR Bowen, Micropatterning of Flexible and Free Standing Polyvinylidene Difluoride

(PVDF) Films for Enhanced Pyroelectric Energy Transformation, Advanced Energy Materials (2015)

Micro-pattering PVDF

88% coverage

45%

63%

28%

Pre-poled extruded PVDF

Photolithograpiic process

Physcial vapour deposition of electrode

Temperatures less than 60°C

Variable geometry/substrate

Durable electrode bonding

Up scaleable

Pattern quality >95%

Temperature, closed circuit current, open circuit voltage

0 10 20 30 40 50 60

-40

-30

-20

-10

0

10

20

30

40

Curr

ent

[nA

]

time [sec.]

45%

70%

88%

100%

0 10 20 30 40 50 60

-60

-40

-20

0

20

40

60

Volt

[V

]

time [sec.]

45%

70%

88%

100%

0 10 20 30 40 50 6035.5

36

36.5

37

37.5

38

38.5

39

39.5

40

40.5

Tem

pera

ture

[C

]

time [sec.]

45%

70%

88%

100%

Optimum coverage

Porous ferroelectrics (James Roscow)

Benefits for porosity in energy harvesting ?

Vibration (piezo)

..also lower heat capacity (increased ΔT).

Heat (pyro)

Summary

Plenty ‘Harvesting’materials

– Ferroelectric polymers and ceramics

– Composites systems

– Electrets

– EAPs

– Triboelectric

– Resonant and non-resonant

– Inertial and kinematic

– Linear and non-linear

– Finding key applications and matching desired power with surrounding environment

Funders:

European Research Council under the European Union's Seventh Framework Programme (FP/2007-2013) / ERC Grant

Agreement no. 320963 on Novel Energy Materials, Engineering Science and Integrated Systems (NEMESIS)

EPSRC, UoB EPSRC KTA, Leverhulme Trust, Royal Society, FP6/7, TSB/DTI, DSTL/Team MAST, NPL, GWR, Airbus,

Moog, Meggit, Renishaw

Reading

C. R. Bowen, H. A. Kim, P. M. Weaver and S. Dunn, Piezoelectric and ferroelectric

materials and structures for energy harvesting applications, Energy and Environmental

Science, DOI: 10.1039/c3ee42454e (2014)

C. R. Bowen, J. Taylor, E. LeBoulbar, D. Zabek, A. Chauhan and R. Vaish, Pyroelectric

materials and devices for energy harvesting applications, Energy & Environmental Science,

DOI: 10.1039/c4ee01759e (2014)

J. Zhang, C. Wang and C. Bowen, Piezoelectric effects and electromechanical theories at

the nanoscale, Nanoscale, DOI: 10.1039/c4nr03756a (2014)

C. R. Bowen and M. H. Arafa, Energy Harvesting Technologies for Tire Pressure Monitoring

Systems, Advanced Energy Materials, 1401787 (2014)