2 Section

Technological development(MCFC)

Technological development(MCFC)

Material used now ANODE: Ni-Cr, Ni-Al CATHODE: LixNi(1-x)O ELECTROLYTE: Li2CO3/K2CO3

Na2CO3

MATRIX: -LiAlO2

ANODE CC: Ni/AISI310S/Ni CATHODE CC: AISI310S SEP. PLATE (AA): AISI310S SEP. PLATE (NAA): AISI310S/Al

Materials actually used in MCFC are suitable to have high electrochemical performance and long operation time

In view of Fuel Cell market, it is still possible to think to improve materials to obtain higher performance, longer operation time and low cost

Technological development(MCFC)

Technological development(Electrochemical Performance)

Reaction Rate Loss mainly depends on materials used for anode and cathode

(catalyst property)

Resistance Loss mainly depends on ionic resistance of electrolyte and electronic resistance of anode, cathode,

metallic components included corrosion layers

Gas Transport Loss mainly depends on anode and cathode

materials morfology

Reaction Rate Loss mainly depends on materials used for anode and cathode

(catalyst property)

Reaction Rate Loss Electrochemical properties of Ni (for H2

oxidation reaction), and NiO (for O2 reduction reaction) are very high

However, limited improvements should be possible by addition of catalyst in standard anode, cathode materials (Cost?, CO use?)

Technological development(Electrochemical Performance)

Resistance Loss Use of thin electrolyte layer decrease ionic

resistance (gas separation problem) Use of electrolyte with low ionic resistance:

Li2CO3/Na2CO3 has lower ionic resistance than Li2CO3/K2CO3

Use of materials for metallic components with higher corrosion resistance (thin corrosion layer with high electrical conductivity corrosion products)

Technological development(Electrochemical Performance)

Gas Transport Loss Porosity, surface area of anode and cathode

are suitable to obtain low gas transport loss (bi-modal morfology of cathode)

However improvement should be possible with higher surface area (nanomaterials?)

Technological development(Electrochemical Performance)

Technological development(Operation time)

Cathode dissolution LixNi(1-x)O has not completely chemical stability

in working conditions Precipitation of Ni in Matrix can produce a

direct electronic contact between anode and cathode

Internal current flow means electrical performance decay

Use of more chemical stable materials should be useful (catalyst for cathodic reaction, high electronic conductivity)

CATHODE (+)

ANODE (-)

MATRIX

Ni++

NiO+CO2 Ni++ + CO3--

Ni++ +H2+ CO3-- Ni + H2O+CO2

Technological development(Operation time)

e

Technological development(Operation time)

Metallic components corrosion Metallic components corrosion means

mechanical property degradation

Anode current collector section OM analysis. a) Before operation b) After operation:it is possible to see Ni coating degradation (lower corrosion protection), and carburisation of AISI310S grains (lower mechanical property)

a)

b)

Technological development(Operation time)

Porous components micro-structural degradation Porosity, pore size distribution, surface area and morfology

of anode and cathode material change in time due to axial load and sintering (Anode)

These changes on electrodes materials mean electrochemical performance degradation (P=0)

Porosity, pore size distribution, surface area and morfology of matrix material could change in time due to -LiAlO2 to -LiAlO2 phase transition (gas composition)

These changes on matrix material mean gas separation property degradation (increase of pore size, matrix not totally filled by electrolyte)

Technological development(Operation time)

Electrolyte loss Electrolyte loss depends on metallic

materials corrosion, vapour phase in gas stream

When electrolyte quantity is not enough to have totally filled matrix, direct contact of H2 and O2 will be possible (electrical performance degradation)

Lab level test(Performance)

Single cell test Single cell is useful to test

electrical performance in lab scale MCFC

Chronogram of single cell voltage/current characterisation.

0

0,2

0,4

0,6

0,8

1

1,2

Time

Vo

ltag

e (V

)

0

5

10

15

Cu

rren

t (A

)

Voltage

Current

Characterisation Voltage and Power/Current Density

0

200

400

600

800

1000

1200

0 50 100 150 200 250 300

Current density (mA/cm2)

Vo

lta

ge

(V

)

0

5

10

15

20

Po

we

r (

W)

Voltage single cell 1

Voltage single cell 2

Power density single cell 1

Power density single cell 2

Lab level test(Performance)

Activation Pol.

Ohmic Pol.

Concentration Pol.

Lab level test(Performance)

Gas analysis In-out single cell gas analysis are performed to

check gas utilisation and possible gas reaction through matrix

Lab level test(Operation time)

Single cell Voltage, Voltage iR free, iR trend

0

100

200

300

400

500

600

700

800

900

1000

1100

0 500 1000 1500 2000 2500 3000 3500 4000

Time(h)

Vo

lta

ge

(m

V)

0

2

4

6

8

10

12

14

16

18

20

iR (

mO

hm

)

V (5,5 A)

IR (mOhm)Matrix filling level control

Lab level test(Operation time)

Lab stack test Lab size stack is useful to test

electrical performance of more cells in stack configuration

10

11

12

13

14

15

16

17

18

19

0 50 100 150 200 250 300 350 400 450 500

Time [unit]

Vo

lta

ge

[V

]

0

10

20

30

40

50

60

70

80

Cu

rre

nt

[A]

Voltage [V]

Current [A]

Lab level test(Operation time)

Post test analysis SEM-EDS

ANODE, CATHODE, MATRIX SEM ANODE, CATHODE, MATRIX SEM ANALYSISANALYSIS

(Micro- structural change) (Micro- structural change)

Lab level test(Operation time)

ANODE, CATHODE, MATRIX PORE SIZE ANALYSISANODE, CATHODE, MATRIX PORE SIZE ANALYSIS

(Micro- structural change) (Micro- structural change)

Lab level test(Operation time)

Porosity reduction

Pore size distribution

change

Lab level test(Operation time)

Crogiolo di allumina

Elettrodo di Nichel porosoimpregnato di carbonati Li/K

Campione metallico(spessore circa 0.3 mm)

Elettrodo di Nichel porosoimpregnato con carbonati Li/K

Caricomeccanico

Camera del forno

TermocoppiaIngresso gas

ANODIC GAS: H2 / CO2 (80/20)

CATHODIC GAS: Air / CO2

T = 650 °C

GAS INThermocouple

Fournace

Metal sample (thickness: 0.3 mm)

Alumina crucible

Porous Ni electrode filled with Li/K carbonate

Porous Ni electrode filled with Li/K carbonate

Pressure load

0

50

100

150

200

250

300

350

400

450

500

0 3000 6000 9000 12000

Corrosion Time (hours)

No

co

rro

ded

sec

tio

n (

mic

ron

s)

Serie1

Trend to 40.000 hours

Lab level test(Operation time)

Material analysis

Lab level test(Cost reduction)

Tape CastingMaterial analysis

Drying

Material analysis

Binder burn out and sintering

Lab level test(Cost reduction)

RAW MATERIALS ANALYSISRAW MATERIALS ANALYSIS

SEMXRD

GRANULOMETRY

Lab level test(Cost reduction)

Use of cheaper raw materials

Conclusion

Fuel cell is an electrochemical device that converts energy of a chemical reaction into electricity without any kind of combustion and with high conversion capability and low environmental emissions.

Molten Carbonate Fuel Cells don’t use expensive catalytic material (Platinum); it can works using CO (reformed natural gas); Operating temperature (650 °C) permit use of stainless steel for metallic components fabrication

MCFC market entry depends on operating life increase and cost reduction. Both points strongly depend on materials used in Fuel Cell preparation