Realising Structural Power: Addressing the Manufacturing Challenges

Structural power composites are mechanically load-bearing materials with the capacity to store and deliver electrical energy. These multifunctional composites are a completely different way of using structural materials, combining two critical technologies (lightweighting and energy storage). Their adoption in transportation, portable electronics and grid infrastructure could significantly help in meeting the NetZero targets. At present, to fulfil range requirements in electric vehicles, a sizable proportion (~25%) of the vehicle weight are the batteries. To reduce this parasitic mass, the conventional approach is to increase battery energy density, but this has considerable sustainability, safety and longevity issues. But by making the vehicle body from structural materials that can store electrical energy, huge weight savings can be made. For example, we've shown that for a given energy density, electric cars made using structural power materials would have about twice the range of that of a car using conventional batteries. In another example, not requiring aircraft wings to be hollow (to store fuel or batteries) would release design constraints: the wings could be very slender, reducing drag, having a profound effect on future aircraft designs and range. Structural power composites have the potential to revolutionise future transportation, portable electronics and infrastructure. However, since the investigators pioneered their development, their translation to industry are being hampered by issues such as poor microstructural control, inconsistent device manufacture, poor scale-up due to inefficient current collection and lack of encapsulation solutions. This proposal aims to address these issues, enabling industrial adoption of structural power composites to the benefit of society.
The research focusses on supercapacitors: energy storage devices that provide rapid charge/discharge cycles. Our structural supercapacitors consist of two carbon-fibre lamina electrodes that are infused with a carbon aerogel (CAG). These electrodes sandwich an ion-conducting, but electrically-insulating, separator and this laminate is infused with a structural electrolyte (SE). The research proposed will be undertaken by a complementary team from Imperial College London (ICL), Durham University (DU) & University of Bristol (UoB), in collaboration with industries ranging from material suppliers (Hexcel, Gen2Carbon & CME), research providers (Hive Composites, NCC & NPL) to OMEs (Airbus & BAE Systems). We will address manufacturing issues for realising structural power, focussing on the interdependent aspects of WP1: Structural Electrolytes (DU), WP2: Device Fabrication (UoB) and WP3: Current Collection and Encapsulation (ICL).
In WP1 (Structural Electrolytes) we will pursue two parallel strategies. The first approach will be using our existing formulation but improve the processability without detrimental effects to its performance. The second, more adventurous approach, is using a different matrix chemistry to produce a more highly refined microstructure in the SE. The formulations under development in WP1 will be adopted in WP2 (Device Fabrication), where we will explore better control of the microstructure during processing either through filming the SE or infusing the SE into the dry electrode/separator stack. To better understand and control the SE microstructure during processing we will design a smart mould which will provide detailed monitoring and control of the flow and cure conditions during manufacture. In WP3 (Current Collection and Encapsulation) we will identify and model materials and processes to minimise the resistive losses and parasitic mass of current collection. Finally, the encapsulation task will identify materials that offer an impervious barrier but can transfer mechanical load into the structural supercapacitor. The work will culminate in demonstration of the best concepts in industry-inspired applications.