Fiber optical sensors for enhanced battery safety

Abstract

Over the last years, battery safety becomes more and more important due to the wide spread of high-capacity lithium ion batteries applied in e.g. consumer electronics and electrical power storages for vehicles or stationary energy storage systems. However, for these types of batteries, malfunctions could be highly dangerous and all aspects of safety issues are not sufficiently considered, yet. Therefore, the improvement of the battery safety behavior is one of the most important issues discussed in actual research projects. In this paper the application of fiber optical sensors for enhanced battery safety is presented. The temperature is one of the most critical parameters indicating a failure of the cell, but even state-to-the-art battery management systems (BMS) are not able to monitor and interpret the distributed temperature field of a total battery storage system sufficiently. Furthermore, the volume expansion of the battery cell, which could be monitored by the strain on the cells' surfaces, is one additional parameter not considered up to now. Both parameters could be simultaneous monitored by fiber optical sensor arrays, consisting of discrete fiber Bragg grating (FBG) elements. The FBG sensors are directly attached on the surface of the cell, recording the temperature as well as the strain distribution highly accurate and close-meshed. Failures and malfunction such as overcharging, gassing, and thermal runaway can be early predicted and avoided to extend the battery lifetime and enhance the operational battery safety. Moreover, battery aging effects lead to variations in the volume change behavior which can be detected additionally. Hence, a battery fully equipped with fiber optical sensor arrays in combination with an appropriate BMS enables a safe and continuous utilization of the energy storage system even under harsh conditions like rapid charging

Fiber Optic Sensing Technologies for Battery Management Systems and Energy Storage Applications

“…Large-format EV-grade Li-ion batteries with a nominal capacity of 15 to 40 Ah have been studied using a fiber optic sensing approach at laboratory scales. [ 20 , 21 , 22 ].…”

“…Other than local point measures, external strain sensing has also been done by quasi-distributed FBGs that monitored the strain evolutions of a 96-cell EV battery pack [ 20 ] and by a Rayleigh-scattering-based distributed FO sensor that studied the strain gradient across the width of a cell [ 108 ]. As most previous FBG strain sensor studies were done with bare fibers that may suffer from low strain sensitivity and instability for long-term monitoring, Peng et al [ 125 ] proposed a strain-sensitivity enhancing protection structure, as shown in Figure 6 a,b, for the FBG fiber attached external to the cell.…”

A review on various temperature-indication methods for Li-ion batteries

“…Others followed quickly with temperature and strain measurements on Li-ion batteries using FBG sensors [247][248][249]. For example, Nascimento and co-workers [249] applied FBG sensors on a cylindrical 18650 Li-ion battery.…”

“…For these reasons, the authors concluded that FBG sensors are a better choice in comparison to thermocouples for real-time monitoring of the battery surface temperature. FBG sensors were also used to monitor temperature and strain in battery packs for enhanced safety in a study by Meyer et al [248]. Every single battery in the pack, containing 96 batteries, was monitored with an FBG temperature sensor on a predetermined hot spot.…”

Development of a Polymeric Arrayed Waveguide Grating Interrogator for Fast and Precise Lithium-Ion Battery Status Monitoring

“…FBG sensors have already been used for status monitoring of lithium-ion batteries by different research groups [18], since they are capable of delivering information beyond conventional BMS. They can serve as simple temperature sensors [19,20], outside and even inside of a cell [21,22], or as functionalized sensor elements that are sensitive to chemical substances and their optical properties [23,24].…”