Lithographically Printed Voltaic Cells
Principal Investigator: D. Southee
Full-Time Research Engineer: G.I. Hay
Co-Investigators: P.S.A. Evans, D. Harrison
Cleaner Electronics Research Group
School of Engineering and Design
Brunel University
Industrial Partners:
Arjo Wiggins: Peter Herdman
Rohm and Haas Electronic Materials: Narinder Bains
DuPont Teijin Films: Bill MacDonald
LPVCs Project Overview
What?
• Investigate the fabrication of voltaic cells (electric cells &
batteries) by the offset lithographic printing process
Why?
• Cleaner Electronics Research Group - Offset lithography has
been adapted to manufacture electronic components and circuit
interconnect on a wide range of flexible materials.
• Costly additional processes and materials required for power
• Market surveys suggest that this is an obstacle to the potential
uptake of the technology
LPVC Project Overview
How?
• Initial work has been carried out on ink formulations suitable for
offset lithography to enable the manufacture of Zinc Carbon
cells
• Initial structures have been manufactured and evaluated
Offset Lithography
• Process used for newspaper and book manufacture
• Dissimilar wetting function of un-embossed plate
• High resolution (printed line widths < 25 microns)
• High speed
• Low cost (dominated by substrate)
Lithographic ink development
Zinc ink formulation
Graphite ink formulation
Particulate size : 3µm
Particulate size : 3µm
Zinc particulate: 75%
Graphite particulate: 33%
Ink vehicle:
Ink vehicle:
Alkyd resin: 90%
Alkyd resin: 77%
Solvent: 9%
Solvent: 22%
Anti-oxidant: 1%
Anti-oxidant: 1%
Both inks displayed shear
thinning and viscosity values
in the region of 7 – 9 Pas at
400 sec-1
1st Iteration Cells
1.5V but very low current……..due to internal resistance
Basic ammonium chloride, manganese (IV)
dioxide, water and polyethylene oxide
electrolyte
1.5 V achievable
2 nA current
2nd Iteration - Electrode Development
• Anode and cathode structures printed on substrate over silver base. Silver layer
employed as current collectors
• Electrolyte, containing
dispersion of Manganese
(IV) dioxide applied to
graphite cathode (+)
• Membrane placed
above electrolyte
• Zinc anode (-) structure
placed above membrane
Printed Cell Characteristics
Printed cell discharge curve through 1kΩ load
Paste – Electrolyte Development
Manganese (IV) dioxide
Electrolyte
Paste formulation:
Liquid formulation:
MnO2: 42.9%
NH4Cl: 25%
C:
Water: 75%
14.2%
Water: 42.9%
Particulate ratio:
75% MnO2 – 25% C
Due to absorbent membrane
Polyethylene oxide has been
omitted.
3rd Iteration - Current Cell Configuration
• Combined Manganese (IV)
dioxide - Ammonium chloride
electrolyte abandoned
• Separate MnO2 – C paste
developed
• NH4Cl – Water solution
contained within membrane
Cell Characteristics
Printed cell discharge curve through 5kΩ continuous load
On-going investigations
I. Shelf life – no load voltage drop off. Possibly due to electrolyte
absorption into substrate.
Possible solutions:
• Adopt non porous polymer substrate – restricts applications
• Contain electrolyte in gel format – replacing membrane and electrolyte
with single gel layer
II. A lithographically deposited MnO2 – C paste?
LPVC Project Overview
Dissemination
•
May 24th – UKDN. ‘Batteries: A new dimension’
Bletchley Park, Milton Keynes, UK.
•
June 21st – PIRA – ‘2nd annual conference on Printed RFID’
Regents Park, London, UK.
•
July 4th – Institute of Circuit Technology annual conference
NPL, Teddington, UK.
•
5th – 7th September - ESTC 2006, ‘Electronic System Integration
Technology conference’
Dresden, Germany.
Power Paper(silk-screen) – Target Capacity for LPVCs?
Power paper
Cell Characteristics
Printed cell discharge curve through no load