Soft materials for enhanced energy storage and conversion
Energy storage and conversion
Energy storage and conversion will become increasingly important in the (near) future - just think of ever more demanding portable devices (e.g. mobile phones & laptops), intermittent renewable-energy resources (e.g. solar and wind) and electric means of transportation (e.g. hybrid & electric cars). As electrochemical storage and conversion will play a crucial role in any plausible scenario, the next generation of batteries and fuel cells should have increased energy density (capacity), charge & discharge rates (power) and lifetimes. Crucial components of these devices are the electrodes, which are the 'electrochemical lungs' and should provide a huge three-phase contact area between 1) reactant or fuel, 2) electrolyte and 3) electronic conductor. Ideally, electrodes are three-dimensional (3D) and have nano-sized features, in order to boost energy density and power. As explained below, soft materials have great potential in the fabrication of advanced materials for enhanced energy storage and conversion.
What is soft matter?
It is "a convenient term for materials in states of matter that are neither simple liquids nor crystalline solids" [1]. More crudely, it referes to 'all things squishy'! Examples in everyday life include paints, pastes, (food) spreads, (blood) cells and polymers such as plastics. They share several characteristic features, one of which is the importance of (multiple) length scales of the order of a few nanometers to a few micrometers, i.e. their building blocks are intermediate in size between atoms and grains. This typically results in enormous interfacial areas and flexible mechanical properties. Moreover, as the interactions between the building blocks can be tailored via surface chemistry and/or external fields (e.g. shear & magnetic), their self-assembly into 1D, 2D or 3D structures can be tuned.
Soft materials for energy applications
As an example of research carried out in the Soft Matter Physics group at the University of Edinburgh, into organizing micron-sized particles using liquid interfaces, see the image below. On the left, it shows an emulsion consisting of water droplets in a continuous oil phase stabilized by micron-sized particles. Simple centrifugation turns this particle-stabilized emulsion into a percolating particle network that is a promising scaffold for the fabrication of enhanced electrodes:
1) it has an enormous 3-phase contact area;
2) it is a 3D percolating network (at a low volume/weight fraction of particles);
3) it is mechanically robust.
Info & contacts:
http://www.ph.ed.ac.uk/research/soft-matter-physics
References:
[1] Richard A.L. Jones, "Soft Condensed Matter (Oxford Master Series in Physics)", Oxford University Press, Oxford, pp.1, 2002.
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Energy storage and conversion in the power grid
Energy storage is fundamental to the creation of the Smart Grid [1,2]. If storage devices can be used to supply home devices at peak electricity consumption times (typically in the morning and evening), then it should be possible to lower peak demand such that fewer carbon-intensive and expensive “peaking plant” generators are required, thus reducing both energy costs and carbon emissions [1]. Furthermore, storage devices can be used to compensate for the variability of typical renewable electricity generation (e.g., wind, wave, solar), thus making the integration of such generation facilities into the existing grid more viable in practice [2]. We from the University of Aberdeen (http://www.abdn.ac.uk/icsmb/) are working on the fundamentals to understand when and how much energy needs to be stored in some models of power-grid.
[1] P. Vytelingum, et al. Agent-based Micro-Storage Management for the Smart Grid, Proc. of 9th Int. Conf. on Autonomous Agents and Multiagent Systems (AAMAS 2010), van der Hoek, Kaminka, Lespérance, Luck and Sen (eds.), May, 10–14, 2010, Toronto,Canada.
[2] D. MacKay. Sustainable energy: without the hot air. UIT, Cambridge, 2009.
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