Traditional lithium-ion battery state monitoring primarily relies on external measurements of current, voltage, and temperature conducted outside the individual cell and inside the battery module. Given that temperature variations such as gradients can significantly impact battery performance, ageing and pose challenges for conventional evaluation methods, localized temperature sensing presents an innovative approach to gain insights into the current state of individual battery cells and the temperature distribution within battery cells and modules. The importance of understanding thermal gradients and their implications has grown in recent years. Moreover, this collected information can be leveraged for load and thermal management by a deployed battery management system.
Traditional methods typically rely on discrete temperature sensors, which often capture only average temperature values and may overlook critical variations in individual cells. Our new fiber-optic measurement approach offers significant advantages in this context: it enables precise, spatially resolved temperature data, with centimeter-level resolution.
This method proves especially valuable for addressing safety-critical concerns, as it allows for the early detection of individual cells exhibiting unusual temperature behaviors—cells that might go undetected with conventional measurement techniques. In our tests, we recorded location-specific temperature events and compared the results with those from traditional monitoring systems. Furthermore, integrating sensors directly into battery cells provides new insights into cell behavior, offering not only temperature data but also correlations with SOC and SOH, allowing for a more comprehensive understanding of cell dynamics.
Our findings underscore the potential of fiber-optic technology to improve battery performance and safety. However, the integration of this measurement technique into existing battery management systems remains an ongoing challenge that we aim to address in future studies.