Mechanical-Electrical Behavior of Multifunctional Energy Storage Composites

Multi-functional Energy Storage Composites (MESC) are composite sandwich structures where battery stack layers are placed between two layers of CFRP and sealed by low-density polyethylene (LDPE), forming a unified material. Because the layered Li-ion stacks have negligible out-of-plain shear stiffness, the two CFRP sheets on both sides of the battery are connected using LDPE rivets that pass through holes cut through the battery layers. The shear transfer mechanism of the rivets substantially enhances the shear stiffness and strength of the MESC. As the first step of preparing a guide for MESC design, the highly coupled mechanical and electrical behavior of MESC was studied through experiments. Several MESC cells were tested under three-point-bending loads. The load, deformation, and electric potential of the MESC were measured, and the electrical and mechanical failures were observed. A finite element model was developed to simulate the electro-chemo-mechanical coupling effect in MESC. In this model, a new constitutive relation of the battery material is proposed and verified by the experimental results. The resulting model can be used to simulate MESCs with various configurations and material properties to provide a design guideline of MESCs in multiple applications.