reversible hydrogen storage potential of a ball-milled ...€¦ · current situation fuel source...

Reversible Hydrogen Storage

Potential of a Ball-Milled

Graphite/LiBH4 Composite

Joshua Vines, H2FC Supergen

16/12/2014

Presentation Overview

Background

Current situation and Aims

LiBH4

Milled graphite

Experimental Techniques

Results

Summary

1

Current Situation

Fuel Source Hydrogen Petrol

Energy Per Unit Mass 142MJkg-1 47MJkg-1

† Schlapbach, L. and A. Zuttel, Hydrogen-storage materials for mobile applications. Nature, 2001. 414(6861): p. 353-358.

2

Gravimetric vs. Volumetric

High Gravimetric

Capacity

High Volumetric

Capacity

Reversible over

1000’s of cycles

3

CnanoHx

Krishna, R., Titus, E., Salimian, M., & Okhay, O. (2012). Hydrogen Storage for Energy Application. Retrieved from http://cms.kdis.edu.cn/cms/et_xjtu/achievements/zhuanzhu/resource/9c32548a54b11506144e0e6abef817eb.pdf

Background: LiBH4 High Gravimetric & Volumetric H2 Density

(18.3 wt% & 121 kg H2 m-3)

High Desorption Temperatures (400-990 °C)

H2 Unpractical Recombination conditions (600 °C, 350 bar H2)

Decomposition Pathway is dependant upon conditions:

– LiBH4 ↔ LiH + B + 3/2H2 (13.8 wt%) (111 kJmol-1)

– LiBH4 ↔ 1/12Li2B12H12 + 5/6LiH + 13/12H2 (10 wt%) (61 kJmol-1)

Daniel Reed and David Book (2009). In-situ Raman study of the thermal decomposition of LiBH4. MRS Proceedings, 1216, 1216-W06-05

Fang, Z.-Z., X.-D. Kang, and P. Wang, Improved hydrogen storage properties of LiBH4 by mechanical milling with various carbon additives.

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2010. 35(15): p. 8247-8252.

Yan, Y., A. Remhof, S.-J. Hw ang, H.-W. Li, P. Mauron, S.-i. Orimo, and A. Züttel, Pressure and temperature dependence of the

decomposition pathway of LiBH4. Physical Chemistry Chemical Physics, 2012. 14(18): p. 6514-6519. 4

Background: LiBH4 + Additions SiO2 (3:1 mass ratio) (Zuttel et al., 2003)

10 wt% H2 Desorbed between 150-600 °C

Not Reversible

Carbon Nanotubes (2:1 mass ratio) (Yu et al., 2007)

H2 Desorbed 250-600 °C

LiH reformed at 400 °C under 100 bar H2 (via formation of Li2C2)

Nanoporous Carbon Aerogel (Gross et al., 2008)

6.4 wt% desorbed between 300-600 °C

LiBH4 Reformed at 400 °C under 100 bar H2

Loss of 40% over 3 cycles

Züttel, A.; Wenger, P.; Rentsch, S.; Sudan, P. LiBH4 A New Hydrogen Storage Material. J. Power Sources 2003, 118, 1–7. Yu, X.B., Z. Wu, Q.R. Chen, Z.L. Li, B.C. Weng, and T.S. Huang, Improved hydrogen storage properties of LiBH4 destabilized by carbon. Applied Physics Letters, 2007. 90(3): p. 034106,034106-3.

Gross, A.F., J.J. Vajo, S.L. Van Atta, and G.L. Olson, Enhanced Hydrogen Storage Kinetics of LiBH4 in Nanoporous Carbon Scaffolds. The Journal of Physical Chemistry C, 2008. 112(14): p. 5651-5657.

5

Background: Graphite Milled Graphite (H2 Atmosphere) (Orimo et al., 1999)

Cheap

Abundant

High Thermal Conductivity

Respectable Gravimetric H2 Density (7.4 wt%)

Very high Desorption Temperatures (400-990 °C)

No Reversibility

Milled Graphite + LiH (2:1) (Ichikawa et al., 2011)

Decrease Desorption Temperatures (200-500 °C)

Induced Reversibility: formation of Li2C2

Methane Desorption

Loss of capacity during cycling (5 wt% - 2.5 wt%)

Orimo, S., G. Majer, T. Fukunaga, A. Zuttel, L. Schlapbach, and H. Fujii, Hydrogen in the mechanically prepared nanostructured graphite. Applied Phy sics Letters,

1999. 75(20): p. 3093-3095.

Ichikaw a H; Kojima, Y, T. M. (2011). Hydrogen Storage Properties of Hydrogenated Graphite and Lithium Hydride Nanocomposite. In B. Reddy

(Ed.), Advances in Diverse Industrial Applications of Nanocomposites (p. 550). InTech.

Zhang, Y. and D. Book, Effect of Milling Conditions on the Purity of Hydrogen Desorbed from Ball-milled Graphite. The Journal of Physical Chemistry C, 2011. 115(51): p. 25285-25289

6

Milled for 40 h, 3 bar H2

Experimental: Sample Preparation

Optimised Conditions†:

Graphite:LiBH4 (2:1)

10 h total mill time: (8+2)

3 bar H2 (Topped up after 2h)

15 min mill 15 min rest

280rpm

†Zhang, Y. and D. Book, Effect of Milling Conditions on the Purity of Hydrogen Desorbed from Ball-milled Graphite. The Journal of Physical Chemistry C, 2011. 115(51): p. 25285-25289. 7

Experimental: Characterisation

Cu Kα (λ = 0.154nm) radiation

Atm Ar (40 mlmin-1) @ 2 °Cmin-1

488nm Laser, 100 mlmin-1

3 bar Ar (100 mlmin-1) @ 2 °Cmin-1

8

Results

9

Graphite+LiBH4: XRD

80604020

2 Theta (°)

Inte

nsity (

a.u

)

As-Received LiBH4

8 h Milled Graphite

10h Milled Graphite+LiBH4

RT 1 bar Ar

As-Received Graphite

10

Graphite+LiBH4: Raman

11

Inte

nsity (

a.u

)

30002500200015001000

Raman Shift (cm-1

)

Graphite+LiBH4

D G G'

8hr Milled Graphite

As-received LiBH4

As-received Graphite

RT 1 bar Ar

[BH4]- Stretching

[BH4]- Bending

Decomposition: DSC

13 Fang, Z.-Z., Kang, X.-D., Wang, P., Li, H.-W., & Orimo, S.-I. (2010). Unexpected dehydrogenation behavior of LiBH4/Mg(BH4)2 mixture associated with the in situ formation of dual-cation borohydride. Journal of Alloys and Compounds, 491(1-2), L1–L4. doi:10.1016/j.jallcom.2009.10.149

DS

C (

a.u

)

500400300200100

Temperature (°C)

Ball Milled Graphite+LiBH4

Endothermic

(3 bar Ar, 2 °Cmin-1

)

8 h Milled Graphite

o-h Phase Change Melting Decomposition

116 °C 280 °C

Decomposition: TGA-MS

12

6

5

4

3

2

1

0

TG

Lo

ss (

wt%

)

500400300200100

Temperature (°C)

3.5x10-9

3.0

2.5

2.0

1.5

1.0

0.5

0.0

H2

Ion

Cu

rren

t

(1 bar Ar, 2 °Cmin-1

)

Graphite+LiBH4 wt% Loss

Graphite+LiBH4 H2 desorption

Decomposition: TGA-MS & DSC

Reversibility: Cyclic Uptake

Cycle wt%

1 2.6

2 2.1

3 1.9

4 1.8

5 1.6

14

H2

Pre

ssu

re (

ba

r)

2.52.01.51.00.50.0

Uptake (wt%)

Isothermal Absorption (350 °C) 112345

0

20

40

60

80

100

1st Rehydrogenation 2nd Rehydrogenation 3rd Rehydrogenation 4th Rehydrogenation 5th Rehydrogenation

Reversibility: XRD

15

Inte

nsity (

a.u

)

706050403020

2 Theta (°)

Li2B12H12

Graphite+LiBH4

Rehydrided Graphite+LiBH4

Li3BO3

RT in Ar

Dehydrided: heated 400 °C under Vacuum

Rehydrided: heated to 350 ° C under 95 bar H2 for 12 h

Summary

Graphite+LiBH4 desorbs 6 wt% H2 at 500 °C

Ball milled hydrogenated graphite reduces the decomposition temperature of pure LiBH4 by ca. 100 °C

Successful recombination of LiBH4 under 95 bar H2 at 350 °C

Loss in cyclic capacity of the material over 6 cycles due to formation of higher boranes and oxidation

16

Future Work/Potential Optimization of de/re-hydrogenation conditions

Prevention of Li2B12H12 formation

Decomposition under 1 bar H2

Removal of oxidation source

Treatment of As-received samples

Minimize graphite content to further increase wt% capacity

Further reduction of decomposition temperatures

Addition of catalysts such as TiF3 and TiCl3

Cheap, fully reversible storage material suitable for stationary

applications

17

Thank you for

listening,

Any Questions?

ACKNOWLEDGMENTS:

PROF. DAVID BOOK DR. DANIEL REED

LUKE HUGHES SHENG GUO

HYDROGEN MATERIALS GROUP

DSC Comparison D

SC

(a.u

)

500400300200100

Temperatre (°C)

Ball Milled Graphite+LiBH4

Endothermic

(3 bar Ar)8 h Milled Graphite

Hand Mixed Graphite+LiBH4

116 °C280 °C

116 °C

286 °C