Lighter-weight, more efficient hybrid cars The hybrid car of the future could be more efficient by drawing power from the car body panels. EU researchers developed prototype structural composite materials that can store and discharge electrical energy and which are also strong and lightweight enough to be used for car parts. Energy Besides a smaller, more efficient engine, today's hybrid cars can use lighter-weight materials to get better mileage. Current bulky batteries reduce the potential impact of hybrid technology. Thin materials that replace parts of the car body can serve as a battery, enabling drivers to cover longer distances before needing to recharge their cars. The EU-funded research project 'Composite structural power storage for hybrid vehicles' (STORAGE) focused on developing novel multifunctional materials that can simultaneously carry mechanical loads and store electrical energy, thus offering significant savings in vehicle system-level mass and volume, or performance benefits such as improved durability. Initial work focused on two techniques for developing the constituents of the composite, namely reinforcing and grafting as well as multifunctional resin. The team improved the material mechanical properties by growing carbon nanotubes on the surface of the carbon fibres. Carbon aerogel coating increased the surface area of the material, improving its capacity to store more energy. On the other hand, the matrix development was based on a mixture of existing epoxy resins and liquid electrolyte. The constituents were then combined to form composite materials. Four multifunctional structural energy storage devices were manufactured, namely capacitors, batteries, supercapacitors and hybrid capacitors. In the end, different techniques were used to test the electrical and mechanical properties of composite materials. Key engineering and operational issues were addressed, beginning with the identification of a multifunctional design approach of carbon fibre laminates, and investigating how to package, integrate and connect the structural power composites within a vehicle structure.Project activities resulted in three demonstrators: a small-scale radio-controlled car with a supercapacitor roof, a plenum cover with lithium-ion batteries and a trunk lid with supercapacitor laminates (saving more than 60 % in weight). Although STORAGE strove to achieve mechanical and electrical performances comparable to existing structural materials and electrical devices respectively, the goal was to demonstrate an overall weight saving of 15 %. These revolutionary developments will help promote cleaner, more efficient and more competitive transport solutions. Keywords Multifunctional material, composite material, mechanical load, energy storage device, hybrid car
