On the damage and performance degradation of multifunctional sandwich structure embedded with lithium-ion batteries under impact loading

The integration of energy storage and load bearing in composite structures provides an alternative ideal solution for the next generation of delivery equipment due to its potential in improving energy storage efficiency and space utilization significantly. However, the susceptibility to impact during services makes it necessary to understand the damage and performance degradation of this multifunctional composite structure and its interaction behavior under impact loads to ensure structural integrity and safety behavior. This study realized the embedded design of lithium-ion batteries (LIBs) into the composite structure and investigated the mechanical-electrochemical coupling behavior of composites-LIB integrated multifunctional sandwich composite structure under low-velocity impact loads. Experimental results showed that the embedded batteries experienced micro short circuits during the impact-loading process and kept good energy-storage capacity after the transient impact. Furthermore, charge-discharge cycling tests results indicated that the abrupt capacity loss increased with impact energy, and degradation rate rapidly deteriorated under high impact energy. Post-mortem inspection revealed that the damage and densification of active materials and separator contributed to the abrupt capacity loss and performance degradation. This work provides valuable insights for the performance evaluation and structural design of multifunctional energy storage composite structures.