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