In situ monitoring of impact-induced capacity loss in structural batteries with flexible electronics

Integrating soft elastomeric capacitors (SECs) into fiberglass composite laminates presents an innovative approach to monitoring impact energy in structural batteries. In high-performance applications, impact damage can lead to catastrophic battery failures, making real-time sensing crucial for safety and reliability. This study evaluates the performance of SECs in detecting and quantifying impact energy in composites with embedded lithium polymer (LiPo) batteries. Composite laminates with only an embedded SEC as well as composite laminates with SEC adhered to batteries were fabricated and tested to achieve this. Tensile testing, digital image correlation analysis, impact tests, and charge–discharge cycling tests were conducted to examine strain sensing, mechanical behavior, and battery performance of the composite structure. Drop-weight impact tests at 3 J to 18 J revealed a direct correlation between capacitance change and impact severity, with laminates containing embedded batteries exhibiting higher capacitance shifts (up to 4.40 pF) and increased energy absorption (up to 12.30 J) in response to higher deformation. SECs remained functional post-impact. The embedded batteries showed minor electrochemical degradation with increasing impact levels, yet remained operational, confirming their structural resilience. These findings confirm that SECs function as effective real-time impact sensors, enhancing structural health monitoring in aerospace, automotive, and renewable energy applications. • Capacitive sensors enable real-time impact and battery monitoring. • Flexible sensors track strain and energy during composite impact. • Embedded battery and SEC stay functional with minimal impact damage.