Simultaneous Sensing of Temperature and Bi-Directional Strain in a Prismatic Li-Ion Battery

Thermal and pressure stability of Li-ion batteries (LiB) are the most important parameters for safety. In abuse operating conditions, the rapid increase of temperature and pressure can cause the appearance of hot-spots, which may lead to an increasing degradation rate or even to the battery’s explosion and/or combustion. A sensing network of fiber Bragg gratings is attached to the surface of a prismatic LiB to monitor its temperature and bi-directional strain variations through normal charge (0.70 C) and two different discharge rates (1.32 C and 5.77 C) in the x- and y-directions. More significant variations are registered when the LiB operates in abnormal conditions. A maximum temperature variation of 27.52 ± 0.13 °C is detected by the sensors located close to the positive electrode side. Regarding strain and consequent length variations, maximum values of 593.58 ± 0.01 µε and 51.05 ± 0.05 µm are respectively obtained by the sensors placed on the y-direction. The sensing network presented can be a solution for the real-time monitoring, multipoint and in operando temperature and bi-directional strain variations in the LiBs, promoting their safety

Customized Optical Fiber Birefringent Sensors to Multipoint and Simultaneous Temperature and Radial Strain Tracking of Lithium‐Ion Batteries

Abstract Batteries are seen as a vital piece for actual carbon‐neutral world needs. However, as they basically operate through extremely exothermic electrochemical events, special attention must be paid to their thermal and volumetric constraints, where continuous and accurate monitoring is of great importance. Considering it, customized optical sensors, based on fiber Bragg gratings recorded in birefringent PANDA fibers (FBG‐PANDA), are developed and instrumented in a coiled configuration into a cylindrical Li‐ion battery (LiB) to simultaneously track temperature and radial strain during galvanostatic cycles, in three different battery locations, for the first time. The maximum temperature and radial strain variations are achieved in the middle and at the end of the discharge steps. This thermal behavior is correlated with the internal heat generation and transfer of thermal energy processes, with a tendency to accumulate in the LiB central zone.Good feasibility and reproducibility are observed in the optical sensor's performance and demonstrated that by operating as a multiparameter decouple system, they can decrease the complexity and intrusiveness in batteries, by using only one optical fiber line. The reported results are in accordance with the literature, indicating that such sensors could be consistently used for future applications regarding battery safety parameters sensing

Reliability and NDT methods

Composites are finding increased use in structural high demanding and high added value applications in advanced industries. A wide diversity exists in terms of matrix type, which can be either polymeric or metallic and type of reinforcements (ceramic, polymeric or metallic). Several technologies have been used to produce these composites; among them, additive manufacturing (AM) is currently being applied. In structural applications, the presence of defects due to fabrication is of major concern, since it affects the performance of a component with negative impact, which can affect, ultimately, human lives. Thus, the detection of defects is highly important, not only surface defects but also barely visible defects. This chapter describes the main types of defects expected in composites produced by AM. The fundamentals of different non-destructive testing (NDT) techniques are briefly discussed, as well as the state of the art of numerical simulation for several NDT techniques. A multiparametric and customized inspection system was developed based on the combination of innovative techniques in modelling and testing. Experimental validation with eddy currents, ultrasounds, X-ray and thermography is presented and analysed, as well as integration of distinctive techniques and 3D scanning characterization.- (undefined