Structural battery

Embedded batteries represent multifunctional structures where lithium-ion battery cells are efficiently embedded into a composite structure, and more often sandwich structures. In a sandwich design, state-of-the-art lithium-ion batteries are embedded forming a core material and bonded in between two thin and strong face sheets (e.g. aluminium). In-plane and bending loads are carried by face sheets while the battery core takes up transverse shear and compression loads as well as storing the electrical energy. The multifunctional structure can then be used as a load-bearing as well as an energy storage material.[7]

In laminated structural electrodes the electrode material possesses an intrinsic load-bearing and energy storage function. One example is for example based on a zinc anode, manganeseoxide cathode and a fiber/ polymer composite electrolyte.[8] The structural electrolyte enables stable charge and discharge performance. This assembly has been demonstrated in an unmanned aerial vehicle. Another material is based on a carbon fiber reinforced polymer (CFRP) concept where carbon fibers serve as electrodes, in addition to their intrinsic mechanical reinforcement purpose. The lamina is composed of carbon fibers that are embedded in a matrix material (e.g. a polymer). Multiple layers of carbon fibers are impregnated with a matrix that enables load transfer between the fibers but also lithium-ion transport, unlike commonly used vinylester or epoxy matrices. This type of energy storage system can be based on a nickel[9] or on lithium-ion chemistry.[10] The laminate is made of the combination of a negative electrode, a separator and a positive electrode, embedded in an ionically conductive and structural electrolyte. In the laminated structural electrodes concept, carbon fibers can be used to intercalate e.g. lithium-ions (structural anode); similarly, to commercially available graphite anodes. The structural cathode consists of carbon fibers coated with electrochemically active species, e.g. lithium oxide particles. Some separator material is used in between the two structural electrodes to prevent short-circuits.[11][12] However, the CFRC concept described above is still being researched.[13]