Materials for Hydrogen Storage

L. Bendersky

Metallurgy Division, NIST
Why hydrogen storage?

2H2+O2->2H2O

How to compact H for automotive

applications ?

(6 kg of H per 300 miles)

 Weight and volume of container

 Time of compaction/fueling (5 min/6

kg)

 Temperature and pressure (<150 C ̊

and 0.3/1.2 MPa)

 Other issues: cost, cycling, heat of

reaction

Gas Liquid Solid
Solid-state hydrogen storage

DOE

targets
Our studies of hydrogen storage materials

Interstitial hydrides

(Ti,Zr)TM2 Laves alloys for Ni-MH

batteries; bcc-based alloys

Complex hydrides (Mg(BH4)2,

LiAlH4 etc)

Raman/PCI, IR emissivity/PCI

Films

Combinatorial high-throughput, kinetics

C15

Zr-Ni

C14

•Ti12.5 Zr21 V10 Ni40.9 Co1.5 Cr8.5 Mn5.6

Prediction of a microstructure in

multicomponent systems

(CALPHAD, solidification path by

THERMO-CALC)
Our studies of hydrogen storage materials

Interstitial hydrides

(Ti,Zr)TM2 Laves alloys for Ni-MH

batteries; bcc-based alloys

Complex hydrides (Mg(BH4)2,

LiAlH4 etc)

Raman/PCI, IR emissivity/PCI

Films

Combinatorial high-throughput, kinetics Maximizing H capacity in compounds:

Distribution of hydrogen in interstitial sites

(tetrahedral, octahedral, other)

AB2H(3-6) compare to AB2T12

Chemistry (energy) of T: AB3, A2B2, A4etc

Max occupancy for multicomponent compound

Path of filling the sites (blocking effect)

Effect on PCI curves

Stress

Laves C15-ZrTi2H4

High-Pressure Metal Hydride Tank for

Fuel Cell Vehicles (Toyota)

Ti-Cr-V-Mn bcc interstitial alloys
Our studies of hydrogen storage materials

Interstitial hydrides

(Ti,Zr)TM2 Laves alloys for Ni-MH

batteries; bcc-based alloys

Complex hydrides (Mg(BH4)2,

LiAlH4 etc)

Raman/PCI, IR emissivity/PCI

Films

Combinatorial high-throughput, kinetics

Nano Li4BN3H10 - MgH2

Identifying phases, modeling Raman or IR

vibration modes

Calculating Raman intensities as a function of

phase fraction or concentration in solid

solution

Understanding optics, scattering from irregular

surfaces (powders), depth
Our studies of hydrogen storage materials

Interstitial hydrides

(Ti,Zr)TM2 Laves alloys for Ni-MH

batteries; bcc-based alloys

Complex hydrides (Mg(BH4)2,

LiAlH4 etc)

Raman/PCI, IR emissivity/PCI

Films

Combinatorial high-throughput, kinetics
Our studies of hydrogen storage materials

Interstitial hydrides

(Ti,Zr)TM2 Laves alloys for Ni-MH

batteries; bcc-based alloys

Complex hydrides (Mg(BH4)2,

LiAlH4 etc)

Raman/PCI, IR emissivity/PCI

Films

Combinatorial high-throughput, kinetics
IR imaging: kinetics of growth in Mg-TM wedge films

Mg-5Ti at%, 3 bar, 373 K

1 nm/sec

0.03 nm/sec

Mg-4Fe at%, 3 bar, 373 K

Mg, Mg-Ti Mg-Fe
Hydrogenated Mg-Ti and Mg-Fe wedge films: TEM

120 nm

Cross-sectional TEM, Mg-5Ti at% film

Cross-sectional TEM, Mg-4Fe at% film
Thick hydrogenated Mg-4Fe film

Mg hydride

Mg hydride

Mg
Different scenarios for formation of hydride phase in films

To be taken into account

1. Dissociation of H2

2. Interaction with Pd

3. Diffusion in M

4. Diffusion in MH

5. Nucleation

6. Growth

7. Effect of defects
Arrhenius plot of the hydride growth rate

as a function of 1/T. An activation energy

obtained from this plot is ~56 +/- 3

kJ/mole

Plot of approximate MgH2 layer thickness

as a function of hydrogenation time. Films

hydrogenated under 0.1 MPa hydrogen

pressure at 363 K, 373 K, 383 K, 393 K,

403 K and 413 K.

Kinetics of hydride growth in Mg-4Fe wedge films

What 56 kJ/mole means?