Structural Power Composites
Weight and volume are at a premium on many structures, and in such applications any material which does not contribute to the load-carrying capacity of a component is structurally parasitic. Increasingly complex requirements, over a range of applications, require a corresponding increase in the efficiency with which systems utilise their mass and volume. For example, firemen are required to wear an array of protective clothing, sensors, communication equipment, and power sources. The total load that individual firemen can carry directly limits the mass of these subsystems. This constraint incurs measurable penalties on performance, such as the thermal resistance of clothing or the range and operating time of communication systems. Another example is aircraft structures which are required to provide mechanical performance whilst reducing total structural weight. Achieving this goal requires efficient implementation of all of the vehicle's subsystems, including structure, power systems, sensing, and communication. Conventional design approaches attempt to maximise the efficiency of the individual subcomponents through the use of advanced materials or new performance technologies. A different approach is to create novel multifunctional materials which simultaneously perform more than one function, thus offering significant savings in system level mass and volume, or performance benefits such as improved durability or redundancy. This design approach is in its infancy, and faces significant design and material synthesis challenges. Disparate material properties, such as mechanical and electromagnetic properties, need to be engineered and optimised simultaneously.
The focus of this research is a multifunctional composite material which can simultaneously carry mechanical loads whilst storing (and delivering) electrical energy. The potential for such a material has been demonstrated by ARL in the USA who showed that considerable weight savings in military structures could be achieved. Polymer composites have now reached a level of maturity at which such adventurous and novel material configurations can be developed. The laminated architecture of fibre composites mirrors the configuration of many current electrical storage devices. In fact, carbon fibre (CF) composites are attractive as they are commonly used as both electrodes and high performance structural reinforcements; usually, the forms of carbon are different, but there is an opportunity to unify these roles with appropriate tailoring of both the matrix and the reinforcement.
The potential applications for structural energy storage materials are numerous and diverse; essentially any load-bearing component in a system which requires electrical energy. Such a material could provide considerable weight and volume savings for applications ranging from lap-tops and mobile phones, specialised applications such as down-hole energy supplies for the petrochemical industry, power supplies for emergency equipment and propulsion systems, hybrid vehicles, through to space and military applications.
Left to right; Dr Kingsley Ho, Dr Natasha Shirshova, Atif Javaid, Dr Sherry Qian
