Design, manufacture and test of a novel structural battery based on sandwich construction

The principles of sandwich construction were used to design, manufacture, and analyze multifunctional sandwich beams that can withstand structural load and also store electrochemical energy. Three sandwich beams were manufactured with aluminum face skins adhesively bonded to cores consisting of unidirectional layers of lithium-ion battery anode and cathode materials stacked across the width of the beam so that their edges can be bonded to the face skins. This novel arrangement of the battery materials enables them to contribute significantly to the through-thickness shear rigidity of the beam. All three beams were tested structurally in three-point bending and one of the beams was also tested for electrochemical performance after being filled with electrolyte. The electrochemically tested beam demonstrated an energy density of 223 W h/L, which is comparable to typical lithium-ion batteries. Stiffness of all the beams was predictable within 10% using a first-order sandwich beam analysis, confirming the existence of composite behavior between the face skins provided by the novel core design. Electrochemical testing had only a minor effect on beam stiffness. The mechanical testing had no significant effect on the battery discharge capacity. The electrochemical test results suggested that compaction of the battery materials and the quality of the electrical connections need to be improved.