Hydrogen (storage)
Technology, a Challenge
for Materials Science
Louis Schlapbach 1,2, Andreas Züttel1, Seiji Suda3
1 Physics Department, University of Fribourg
2 EMPA, Swiss Federal Lab for Materials Research and Testing,
Dübendorf- Zürich
3 Hydrogen Energy Technology Lab, Kogakuin University
Hachioji-shi, Tokyo
louis.schlapbach@empa.ch
Supported by Swiss DOE and EU-Projects
Stationary energy storage
(heat, power)
Natural forces Ratio Example Store technique
Gravitation 100 Mechanical Hydropower
Weak Nuclear 1033
Electromagnetic 1038 Chemical Hydrogen synthetic fuel
Electric battery
Weak Nuclear 1040 Nuclear fission, Nuclear fuel
fusion
Mobile energy (fuel) storage
globalisation: mobility of persons
transport of goods
emissions, greenhouse gases, CO2
global warming, more breathing problems
use hydrogen, a C-free, clean efficient fuel
Electric power for cableless devices
portable ICT devices
portable devices for medical technology
cableless safety/surveillance devices, sensors
cableless tools
auxiliary electric power units
use high power density metal hydride
electrode batteries or future small fuel
cells with hydrogen (H, H-, H+)
Materials synthesis,
processing, functionalization
amorphous Silicon solar cells
diamond thin films for high frequency electronics
hydrogen plasma treatment of surfaces
hydrogen in thermoelectrics
switch transparency to reflectivity
use hydrogen to functionalize materials
(Seebeck effect)
Thermal energy can be directly converted into electricity.
Heat source
Hot TH
junction p n
Cold
junction TC
Heat sink
I
R, power generation
A thermoelectric generator is a unique heat engine in which “the electron gas serves as working
fluid”.
z
α 2 ⋅σ The efficiency η of a thermoelectric device is related to z:
z= η ~ (1 + zT)1/2.
k
For maximum device efficiency Isolators Semiconductors Metals
one needs to maximise z:
α2.σ σ
α
Seebeck coefficient α
Electrical conductivity σ
Thermal conductivity k ≈ 1019
(k = klattice + kelectrons) Carrier concentration [cm-3]
Semiconductors with a carrier concentration of 1019 [cm-3] satisfy the necessary criteria better
than other materials.
Interstitial atoms like hydrogen, nitrogen to modify the electronic structure and phonon spectrum
Why hydrogen?
Why not already today?
Hydrogen
Atomic Number Symbol Atomic Mass HYDROGEN on EARTH
Boiling
Point [K] 1.0079
20.288
Melting
Point [K] 14.025
Density 0.0899
[gcm-3] 1s1
at 300K
Electron
Hydrogen
Configuration Name
Isotopes
2H2O 2H2 + O2
Hydrogen Deuterium Tritium
Properties of hydrogen
non toxic, C-free gas, unlimited available as H2O
simplest element of periodic table
best ratio of valence electrous to nucleons:
1e- per 1 proton
isotopes D deuterium, T tritium for nuclear fission and
fusion reaction
molecular gas H2, liquid T wall thickness d= D= 0.1 m 0 1.4 mm
20 6000
composite density ρ = 3 g/m3 1,5 kg container
length L = lm
0,5 kg H2
gas volume V=8l
–> 25 mass% H
2
Hydrogen storage
Storage Media Volume Mass Pressure Temp.
Hydrogen gas
(298 K, 25°C)
0.01 mol H2·cm-3
at 200 bar
Liquid hydrogen
(21 K, -252°C)
0.0708 g·cm-3
0.0354 mol H2·cm-3
at 1 bar
Absorbed hydrogen
(298 K, 25°C)
e.g. LaNi5H6
0.05 mol H2·cm-3
at 2 bar
Adsorbed hydrogen
(65 K, -208°C)
0.01 mol H2·cm-3
at 70 bar
Adsorption:
Physisorption, Chemisorption
high surface area materials
intercalation
micro-, nanoporous material
layered structures
effect of curvature
Hydrogen absorbtion mechanism
H2 gas phase alkaline electrolyte
1) Physisorption of H2 molecules 1) Physisorption of H2O molecules
2) Dissoziation (activation barrier) 2) Electron transfer (desorption of OH- )
3) Chemisorption of H-atoms 3) Chemisorption of H-atoms
4) Diffusion of H-atoms 4) Diffusion of H-atoms
5) Intercalation 5) Intercalation
PHASE TRANSITION IN METAL HYDRIDES
æ pö
R ⋅ T ⋅ lnç ÷ = ∆H − T ⋅ ∆S
çp ÷
è 0ø
Tc β − Phase ∆S 80
R
α − Phase
100 60
100°C
40
peq [bar]
E [mV]
∆H
0
10 −
α + β − Phase
R 20
25°C
1 0
0°C
-20
0.1
0.0 0.2 0.4 0.6 0.8 1.0 2.4 2.8 3.2 3.6
cH [H/M] -1 -3 -1
T [10 K ]
SOLID FORMS OF CARBON
Phase
diagram
T [°C]
Graphite (hexagonal) 0 1000 2000 3000 4000
Diamond (cubic)
6 4
10 10
Solid III
(Metallic) Liquid
5 3
10 10
Diamond
4 Lonsdaelite 2
10 10
Diamond
p [kPa]
p [bar]
3 1
10 10
2 0
10 Graphite 10
1 -1
10 10
Lonsdaelite 0
Vapor
-2
C60
10 10
0 1000 2000 3000 4000 5000
T [K]
Ref.: D.R. Gaskell, “Introduction to Metallurgical
Thermodynamics” Oxford (1993) Pergamon
Press
Nanotubes
Hydrogen condensation in and on nanotubes
d [nm]
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
8
Ns = 1
6
H/(H+C) mass [%]
Ns = 2
4
Ns = 5
2
Ns = 10
0
0 2 4 6 8 10
Ns
SWNT sample from Dynamic Enterprises Ltd.
1.0 600
T = 293 K 2nd 250 T = 293 K
cycle T = 303 K 2.0
500 T = 313 K
0.8 T = 323 K
200
400 1.5
H/(H+C) [mass%]
H/(H+C) [mass%]
0.6 3rd
Q[mAh·g ]
Q [mAhg ]
-1
150
cycle
300
1.0
0.4 -1
100
200
0.5
0.2 50 100
0.0 0 0 0.0
0.01 0.1 1 10 100 0.01 0.1 1 10 100 1000
t [h] t [h]
BALL MILLING OF GRAPHITE SPCIFIC SURFACE AREA
Diffraction pattern of nanostructured Specific surface area (BET) vs. milling
graphite for several milling times. time
Ball milled: Graphite, 1 MPa hydrogen
gas
Shin-Ichi Orimo et al., Applied Physics Letters 75, No. 20 (1999), pp. 3093-3095
Other materials to adsorbe or
intercalate hydrogen
layered structures
hexagonal Al B2
trigonal Ca Si2
orthogonal Ru B2
hexagonal Re B2
hexagonal W B2
high surface area nanostructures
Li Al O2
high (open) porosity nanostructures
zeolites
Hydrogen generated by the hydrolysis
of Alkaline Borohydrides
MH complex Mol. mass H-content H-generated (mass%)
(mass%) (Hydrolysis)
LiAlH4 37.93 10.53 10.82
LiBH4 17.85 22.41 14.86
KAlH4 70.08 5.71 7.54
KBH4 53.91 7.42 8.90
NaAlH4 53.97 7.41 8.89
NaBH4 37.70 10.61 10.85
Chemical and Electrochemical Applications
of Hydrogen
1. H2 (Diatomic hydrogen) H2 2Ho (Protium) (inMH)
2. Ho (Protium) H+ (Proton)+e- (in Ni-MH battery)
3. H2 2Ho 2H+ +2 e- (in PEMFC)
4. 4 H- (Protide in BH-4) + 2H2O 4H2 (for PEMFC)
5. H- (Protide in BH-4) H+ + 2e- (in BFC)
VOLUMETRIC VS. GRAVIMETRIC DENSITY
Conclusions
we learnt a lot on reversible hydrides of intermetallic
compounds
their chance to be the future H2-storage material is not
(yet)so good.
curved/bent carbon nanostructures do not offer
significant advantage over high surface area graphite.
complex hydrides, ionic hydrides, slurries should be
studied in more details.
for electricity generation (fuel cell) H- is more attractive
than Ho
efficient use of energy is a must
if we care for nature and mankind
Statistics related
to energy consumption
WORLD CLIMATE CHANGE
Spektrum der Wissenschaft Mai 2001, pp. 90-91
WORLD ENERGY ECONOMY
Energy carrier Demand Reserve Average Power Consumption per Person kW
[years]
Fossile
Crude Oil 32.7 % 41
5 6
Natural Gas 19.5 % 63 10
Coal 21.4 % 218 50% in buildings
>50% for mobility and transport
technologies are availabe on the market to decrease
energy
in buildings to 25%
for mobility of persons to 50%
efficient use of energy is a must
if we care for nature and mankind
include social sciences for
learning processes