Hydrogen storage in nano- structured graphite: a solution for economic energy storage for low- carbon vehicles and the buffering of renewable energy? Yinghe Zhang, Dr David Book, Prof. Rex Harris School of Metallurgy and Materials, University of Birmingham, UK

Hydrogen as a fuel for the future Nanostructured carbon-based materials for hydrogen storage Outline

1.1 Hydrogen economy

Ref. Louis Schlapbach & Andreas Züttel, NATURE, 414, p.353, (2001) 110l 57l 33l26l Mg 2 FeH 6 LaNi 5 H 6 H 2 (liquid) H 2 (200 bar) 1.2 Ways to store hydrogen 4 kg hydrogen Compressed hydrogen Liquid hydrogen Solid-state hydrogen storage materials Issues: weight, cost, reaction kinetics and reversibility

Ref. [1] Shunsuke MUTO, Japanese Journal of Applied Physics, 44,2005 [2] Scanning Electron Microscopy secondary mode micrographs of: (a) as-received graphite (b)graphite milled for 40 hours (3 bar H2) Particle size Specific surface area Interlayer distance (d- space) Defects- intermediate state for H 2 storage (a)(b) H atoms d-space d’-space 2.1 Nanostructured graphite made by ball-milling

(c) Schematic depicting the ball motion inside the ball mill. (a) Retsch PM400 Planetary Ball Mill. (b) Milling pot and balls

2.2 Previous Work on Graphite Graphite milled in a hydrogen atmosphere (10 bar) in a ball-mill for 80 hours can absorb 7.4 wt% hydrogen 1. Ref. 1. S. Orimo, et al, Applied physics letters, (1999) 75, 20, T. Ichikawa, et al, Materials Science and Engineering B108 pp138–142 (2004) 3. T. Ichikawa, et al, Appl. Phys. Lett.86, (2005) However, release hydrogen at 600 K it was not reversible So additions (e.g. LiH, Fe) were introduced 2,3

Amount of hydrogen and methane desorbed from graphite milled in hydrogen (3 bar) for various times (0~40 hours). Calculated from Thermal Gravimetric Analysis-Mass spectrometer ( TGA-MS) measurement. (WC milling pot, 3bar H 2 ) 10 hours 2.3 Results and discussion

(c)(a)(b) High Resolution Transmission Electron Microscopy image of: (a) as-received graphite; (b) graphite milled for 10 hours and (c) graphite milled for 40 hours (3 bar H2). The relationship between milling time and average graphene interlayer space

2.4 Conclusion Hydrogen is a clean and sustainable energy Nanotechnology is being used to develop graphite for storing hydrogen Under the conditions used in this study, it was found that the optimum milling time (to maximize the amount of hydrogen stored and minimise methane release) was 10 hours. It was shown that the interlayer distance can be related to the hydrogen storage properties of the milled graphite.

2.5 Future work The relationship between the structure of milled graphite and hydrogen storage properties (Raman, EELS) The effect of additions The function of impurity

Yinghe Zhang Group Website: Thank you !

Introduction of Hydrogen Materials Group Head of Group Major research areas: 1) development of novel materials for solid-state hydrogen storage 2) fabrication of dense-metal membranes for hydrogen purification 3) use of hydrogen in the microstructural processing of materials 4) H 2 energy demonstration projects (e.g. PROTIUM Hydrogen Canal Boat) Dr David Book

PROTIUM Project: Hydrogen Canal Boat The "Ross Barlow", was officially launched on 21 September 2007 at the Mailbox in the centre of Birmingham BBC Midlands Today: Professor Rex Harris FREng

(b) Effect of Lithium Hydride additions to milled graphite 2 (a) Effect of Fe 1 [1] T. Ichikawa, et al, Materials Science and Engineering B108 pp138–142 (2004) [2] T. Ichikawa, et al, Appl. Phys. Lett.86, (2005) Hydrogenation: 10bar, H 2, milled grapihte: LiH=2:1 milled for 2 hrs Rehydrogenation: 10bar, H 2, for 8 hrs 10bar, H 2, graphite+Fe power 1 atom% milled for 80hrs

Ball milling of graphite under a hydrogen atmosphere is an effective method of producing nanostructured graphite which is able to store an appreciable amount of hydrogen. Under the conditions used in this study, it was found that the optimum milling time (to maximize the amount of hydrogen stored and minimise methane release) was 10 hours. It was shown that the interlayer distance can be related to the hydrogen storage properties of the milled graphite. Nanostructured graphite has potential for use as a low- cost in energy store, for vehicles and stationary hydrogen-energy applications. 3.3 Conclusions