High-performance multifunctional energy storage-corrugated lattice core sandwich structure via continuous carbon fiber (CCF)/polyamide 6 (PA6) 3D printing

In this study, an energy storage multifunctional sandwich structure (ESMS) was designed to perform well-balanced and excellent multifunctional performance. The corrugated core sandwich structure was newly developed to prevent the degradation of mechanical properties even when lithium polymer (LiPo) batteries are integrated. The empty space of the corrugated core was used as an energy storage space, and the corrugated core was fabricated via 3D printing technology using a continuous carbon fiber filament. The energy storage characteristics were implemented using LiPo batteries embedded in the neutral axis of the sandwich structure. The static and fatigue bending properties of the ESMSs were analyzed through a three-point bending (3PB) test. A battery charge/discharge test was performed before and after the mechanical tests to analyze the effect of bending loading on the energy storage properties. The conventional foam-core ESMS showed negative changes in flexural properties such as strength (−27% in Foam-SH) and modulus (−22% in Foam-AD) due to the battery embedding. On the other hand, in the case of the 3D-printed core ESMS, no degradation in mechanical properties was observed even though the energy density was 1.7 times higher than that of the foam-core ESMS. Furthermore, no defects or delamination were found in the battery embedded in the 3D-printed core ESMS, unlike the battery embedded in the foam-core ESMS where delamination between the separator, anode, and cathodes occurred after the 3 PB test. Consequently, a 3D-printed core ESMS with superior balanced multifunctional performance can be implemented without degradation of both the mechanical properties and energy storage characteristics.