**Author details**

**4. Perspective and future developments**

526 Syntheses and Applications of Carbon Nanotubes and Their Composites

these materials provide.

With energy consumption as a whole on the increase, coupled with the rapid economic de‐ velopment of countries such as Brazil, China, India, and Russia there will be a concerted ef‐ fort to improve how energy is utilised. This expansion in industrialisation has already and will continue to lead to a further increase in the price of oil. Coupled to the rise in fossil fuel costs are drivers of an ageing energy infrastructure system and demand for a low-carbon emission economy through the use of renewable energy [155]. To help accommodate all these factors the supply and demand challenge may be addressed by tapping into otherwise wasted energy. Low grade heat, if effectively harvested can prove to be a viable source of power. Thermal converters have the potential to increase the efficiency of current energy conversion systems. Energy storage also plays a key role in providing a solution to the ener‐ gy problem. Energy must be efficiently stored, when it is in excess, and released at a time of high demand. This is extremely important for renewables that are not load-following [156]. With these energy challenges and ongoing research and development, including those that have been conducted over the last decade, the awareness of the benefits of electrochemical capacitors is increasing. As the research and development into energy storage and conver‐ sion has increased, the applications of electrochemical capacitors has increased with the technology becoming more diverse meaning that systems can better be tailored /targeted for specific applications ranging from higher energy density to high power densities where fast charge / discharge efficiencies are needed [156]. The most commonly used material for su‐ percapacitors has been activated carbon with new nanostructured materials such as carbon nanotubes and its derivatives coming to the forefront of the current fundamental research. It can be seen that the way forward in terms of trying to improve energy density and power density is in the use of CNT with composite materials such as other carbons, and conducting polymers or metal oxides in order to take advantage of the pseudocapacitative effects that

The research on thermogalvanic systems in the past has been generally limited to platinum electrodes [100]. This has enhanced the understanding of these electrochemical systems but has not advanced the research in terms of commercialisation due to its cost. The use of car‐ bon nanomaterials has improved the performance of these devices immensely because of their fast transfer kinetics and large electroactive surface area and is also economically via‐ ble. A record threefold increase in power conversion efficiency (as compared to convention‐ al systems wherein platinum is used) has been realised with the use of MWNT electrodes [114]. Flexible electrodes are now possible due to CNTs. These can be used as scroll electro‐ des or for thermocells that can be wrapped around pipes will make this system more versa‐ tile in terms of its possible applications. Further increase in thermocell performance may be

Future development will most likely see supercapacitors and thermocells become a central part of hybrid energy storage and power delivery systems for large scale and domestic de‐ mand strategies. The integration of these two systems into one device will allow the convert‐ ed waste heat to be stored then released when deemed necessary. These future

realised with the use of CNTs-graphene composite materials.

Dennis Antiohos\* , Mark Romano, Jun Chen\* and Joselito M. Razal

\*Address all correspondence to: junc@uow.edu.au

Intelligent Polymer Research Institute, Australian Institute of Innovative Materials, Innova‐ tion Campus, University of Wollongong, Australia
