Multi-Functional Nanocomposite

Materials for Low-temperature Ceramic Fuel Cells

Indian Coordinator: Prof. Suddhasatwa Basu, Department of

Chemical Engineering, I.I.T. Delhi, New Delhi 110016 And

European Coordinator: Prof. Peter Lund, Department of Engineering Physics, Aalto University, Finland

Other Partners:

Prof. F. Marques University of Aveiro, Portugal

Prof. T. Norby, University of Oslo, Norway

Mr Ibrahim Pamuk, VSS Turkey

Dr. R. N. Basu, CSIR-CGCRI, India

Objectives

2

Scientific basis of multi-functional nanocomposite materials and developing durable Low Temperature Ceramic Fuel Cell (LTCFC)

Building a 25W unit cells under cooperation of academic and industrial partners as a demo for technology

The cooperative objective is to increase the impact and international visibility of research on novel LTCFC both in Europe and India via establishing long-term collaboration and synergy among the partners;

Train talented young researchers on leading-edge research techniques for development of the state-of-the-art LTCFC technologies in the EU and India through promoting exchange of researchers.

Scientific Basis

3

(a, b) TEM image and HRTEM image of core-shell SDC-Na2CO3 nanocomposite;

(c) Cross section SEM image of a single cell made of SDC nanowires/Na2CO3

nanocomposite electrolyte

(d) A closer view of the electrolyte layer which clearly shows nanowire structure.

Core shell structure of Carbonate and SDC Structure Property Relationship

R. Chockalingam, S. Basu, Int J Hydrogen Energ 2011, 36, 14977. R. Chockalingam, S. Jain, S. Basu, Integr Ferroelectr 2010, 116, 23. R. Chockalingam, A. K. Ganguli, S. Basu, Ceramic Engineering and Science Proceedings 2013, 33, 35.

a b

C d

a: SDC-Na2CO3 synthesized through Freeze drier method

c and d: synthesized through co-precipitation method (the mark is 200 nm)

Fig. 1 (a, c, d): SDC-Na2CO3 synthesized through different methods.

c, d from: Int. J. Energy Res.2009;33:1126–1137

Electrolyte: SDC (Ce8Sm2O19) + LiNaKCO3 → (C-SDC) Electrode: Li1Ni4CuZn2O14

B. Zhu, Y. Ma, X. Wang, R. Raza, H. Qin, L. Fan, Electrochem Commun 2011, 13, 225.

B. Zhu, H. Qin, R. Raza, Q. Liu, L. Fan, J. Patakangas, P. Lund, Int J Hydrogen Energ 2011, 36, 8536

Innovative Aspect

Single Component Fuel Cell Structure

Combining semiconductor oxides and ion-conducting material

Oxides of Ni, Cu, Zn, Fe, Co – semiconductors. Doped ceria, such as Gd3+ or Sm3+ doped ceria (GDC or SDC)

Use of SPS and conventional wet synthesis route

Optimizing composition of nano-composites

Micro scale LTCFC development and scale up (macro-scale engineering)

5

Kick-off meeting and workshop held Oct 9-10, 2014 at IIT Delhi

Reactions of CO2 in Fuel cell!

Fig . The Alkali ions ( Li+, Na+, K+ ) and CO2. (M: Na, K, Li ions)

O2+(2,4)e-= O2-(O2

2-, 2O2-)

NC/LC

C2O42-, C2O5

2-, CO32-,

HCO3-, …

CO2, O2, H2, … Na+, K+, …

e-?

CO2+O2-=CO32-

CO2+O2-

=CO32- CGO

O2+4e-=2O2-

CO2 O2 H2

Open questions! university of aveiro

portugal

Ce Na

C

Microstructural effects Melting

LiOH 462 °C NaOH 318 °C NLC 499 °C

university of aveiro

portugal

0 100 200 300 400

0

100

200

300

400CGO15 substrate:

Porous

Soaked with NLC

Washed with HCl

-Z'' (

k

. c

m)

Z' (k. cm)

0 20 40 60 80 1000

20

40

60

-Z'' (

k

. c

m)

Z' (k. cm)

The high frequency

arc is representative

of bulk oxide-ion

transport!

Non-destructive analysis

Skeleton before

impregnation

After

impregnation

university of aveiro

portugal

Transport process – transference no.

Aims:

Investigation of the transport processes and charge carriers in carbonate–

ceramic composite electrolytes

Assessment of proton conduction in carbonate–ceramic composites

(Samples from Prof. F. Marques, Portugal)

Characterisation techniques:

Electromotive force (EMF) measurements to obtain transport numbers in

controlled atmospheres

Electrochemical impedance spectroscopy to study electrode polarisation

transport numbers for carbonate, alkali metal

and oxide ions are close to unity in small pO2

gradients

polarisation resistances depends on pCO2

(next slide)

transport numbers for hydroxide ions are

similar in both samples

no significant impact of pH2O on the

polarisation resistance

Transport numbers in different gradients

pO2 gradient in dry CO2 + O2

pH2O gradient in O2 + CO2

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.80.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

POR2 (Au electrodes)

t ion

Ln[pO2

(high) / pO

2

(low)]

500ºC

pCO2 = 0.78 atm

223 &, OMCO

t

0.4 0.6 0.8 1.0 1.2 1.4 1.60.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

t ion

Ln[pH2O

(high) / pH

2O

(low)]

POR1 (Ag electrodes)

POR2 (Au electrodes)

500ºC

pO2 = 0.21 atm

pCO2 = 0.76 atm

OHt

Electrode polarisation resistances

0.2 0.4 0.6 0.8 1.00

500

1000

1500

2000

2500

3000

3500 O

2 / CO

2 (wet)

O2 / Ar (wet)

Rp

Log (pO2 (atm))

Au electrodes

500ºC

Rp measured at zero partial pressure

gradient between both sides of cell

larger polarisation resistances when

CO2 is present

Large polarisation resistances may lead

to underestimation of transport numbers

Calcination

Aqueous soln. of chelating

agent

60oC Stirring

ZrO(NO3)2.xH2O Y(NO3)3.6H2O +

Homogeneous

sol (pH 3)

8YSZ gel

60oC

Stirring

120oC

Drying

Gel powder

Nano crystalline 8YSZ powder

Synthesis of 8YSZ Powder by Sol-gel Process

600oC

CGCRI Kolkata

Synthesis and Standardization of Electrolyte

Sintering temperature (0C) σ

(S/cm) at

10000C

Activation energy

(eV) (8000C-

10000C)

1000 2.8×10-3 1.5

1100 4.77×10-3 1.59

1200 0.107 1.82

1300 0.195 1.72

1400 0.217 1.3

Characterization of 8YSZ Synthesized by Sol-gel Process

TEM of 8YSZ powder calcined at 600°C: Particle size 5-7 nm

FESEM of 8YSZ sintered samples: Sub-micron sized grains were obtained up to 1200°C (200-300 nm) Greater than 97% densification was obtained at 1200°C. Beyond 1200°C, grain growth was observed.

XRD of 8YSZ powder calcined different temperatures: Well crystallized phase pure 8YSZ were obtained at all calcination temperatures.

Electrical conductivities and activation energy of sintered 8YSZ pellets:

at 12000C , 0.107 S/cm is achieved whose microstructure contains

dense submicron sized grains.

Arrhenius plot gives a linear relationship wirh sintering temperature

and activation energy was calculated to be 1.82 eV.

CGCRI Kolkata

Mixed Solution

MnCl2

Hydrothermal Treatment

Product

Phase Pure LSM Nano Powder

Heating & Stirring

Wash with Water & Ethanol Overnight Drying (120 oC)

KMnO4

Metal Acetates

KOH

Schematic of hydrothermal synthesis of Shape tailored LSM Powder

CGCRI Kolkata

Aim of Vestel

• To develop having a power density of 1000 mW/cm² at 500-600˚C ceramic membranes.

• To move from laboratory scale research to device manufacturing and scaling-up to engineering-size fuel cells.

• Step to commercalization: demostration of 25W LTCFCs.

Vestel Defence Industries Inc

Methods for Project

• Sytnhesis of different nanocomposites (by using different synthesis tecniques including novel wet chemistry synthesis. )

• Characterization of materials by using advanced tecniques: HR-TEM, TEM, SEM, XRD, thermal analysis, XPS and EDX.

• Production of micro scale nano fuel cell and electrolyte pellets (10-15 mm) using hot/cold press and SPS tecniques.

• Experimental analysis of developed materials: empedance, 4-probe DC test and performance measurements.

• Development of 25-36 cm2 (active area ) cells (after characterization and optimization studies on the nanocomposite material and test cell.)

Vestel Defence Industries Inc

Methods for Vestel Design of a single cell

• Modeling of a single cell with initial size (a button cell) • Producing a single cell with initial size • Developing and finding solutions for cell sealant

Design of a single cell (5•5 / 6•6 cm²)

• Modifying the initial size to larger with aforementioned steps and capabilities

Design of a single cell (5•5 / 6•6 cm² or larger)

• Modifying the large size to largest size with aforementioned steps and capabilities • Testing for commercially acceptable life time

Design of a stack (at least 5 cells)

• Testing for commercially acceptable life time • Testing for commercially acceptable start-stopp times for acceptable degradation • Testing with synthetic reformate gas (mixture of H2, CO, CO2 and H2O) if possible

Vestel Defence Industries Inc

Summary

EMF measurements:

alkali metal, carbonate, and oxide ions play significant roles in the

transport processes of carbonate–ceramic composite electrolytes

protonic conduction was of varying significance and mainly due to

hydroxide ions

Impedance measurements:

electrode polarisation resistances have an impact on the transport

numbers; correction for artefacts is needed to avoid over- or under-

estimated transport numbers

further systematic studies are still required

Vestel Defence Industries Inc. Turkey

university of aveiro

portugal

First workshop held Oct 9-10, 2014

CGCRI Kolkata