Implantable graphene/PVA-coated glass fiber for real-time strain monitoring in structural batteries under electrochemical cycling and external loading

Abstract

Highly sensitive sensors integrated into structural batteries enable real-time monitoring of the strain state in the operation period, providing early warnings against thermal runaway and fire hazards in commercial energy storage devices. This study develops an implantable graphene-polyvinyl alcohol (PVA)-coated glass fiber sensor (GP-GFS) fabricated via dip-coating, for monitoring the strain of structural batteries induced by electrochemical cycling and external loading. The GP-GFS achieves exceptional sensitivity with a gauge factor of 8.6, ultralow strain detection limits (0.009 % tensile, 0.028 % flexural), and maintains 98.5 % piezoresistive responses over 2000 tensile cycles. Embedded within a four-layer glass fiber reinforced polymer composites-encapsulated lithium-ion (Li-ion) pouch cell, the GP-GFS placed across the pouch cell surface enables real-time tracking the internal strain arising from Li-ion intercalation/deintercalation during charge–discharge cycles. In addition, the GP-GFS can rapidly respond to external impact, enabling real-time detection of collision-induced microcracks in the structural battery. It addresses a critical gap in battery management systems (BMS), which remain insensitive to non-electrochemical mechanical perturbations. This work opens new avenues for enhancing the safety and reliability of next-generation energy storage systems by providing a simple yet effective monitoring approach.