Abstract
Lithium-ion battery is one of the most versatile energy storage technologies today, and the reliability and safety of lithium battery have always been the target pursued by the industry all the time, so it is particularly important to accurately monitor the safety status of the battery. Actually, the ultimate cause of all lithium battery safety problems lies in the thermal runaway inside the lithium battery. In order to overcome the current problems of temperature measurement systems, such as low accuracy and insufficient stability for long-time operation at relatively high temperature, a temperature monitoring system of quasi-distributed lithium battery based on double clad Fiber Bragg Grating (FBG) is proposed in this work. After the monitoring of the temperature field and bulge deformation of 18650 lithium battery pack by building 4 channels and 16 double clad FBG points to monitor the temperature field and bulge deformation of 18650 lithium battery pack, the results show that the points with abnormal temperature rise caused by short circuit and other problems can be accurately determined under the temperature of 0–450 ℃, with the corresponding temperature sensitivity of 10 pm/℃, and the resolution of 0.1 ℃. The double clad FBG attached to the surface of the lithium battery shell can also monitor the bulge deformation on the surface of the battery shell, and its longitudinal pressure modification sensitivity is up to 142 pm/N. The temperature field monitoring system of quasi-distributed lithium battery pack based on double clad FBG in this paper can not only ensure high-precision temperature and deformation measurement, but also have good stability and anti-interference ability, which shows that the research work in this paper is expected to provide a reliable theoretical and experimental basis for the safety monitoring and use of lithium battery pack.
Highlights
图 5(a)Fiber Bragg Grating (FBG) 中心波长实时监测;(b)FBG 中心波长随压力变化;(c)FBG 中心波长随位移变化 Fig. 5. (a) Real-time monitoring of FBG center wavelength; (b) FBG center wavelength varies with pressure; (c) FBG center wavelength varies with displacement
总之,本文研究了双包层 Fiber Bragg Grating (FBG) 的温度与应力应变的传感特性,获得的双包层 FBG 在 0 ~450 °C测温范围内温度灵敏度为 10 pm/°C,温度分辨率为 0.1 °C,纵向压力应变灵 敏度为 142 pm/N,均优于一般单模 FBG 温度和应力应变灵敏度,且中心波长漂移量与 温度及应力应变的线性关系拟合度更好。进一步基于双包层 FBG 设计了多点准分布式 传感系统,探讨了其在锂电池使用过程中温度与形变监测情况,实现了对 18650 锂离子 电池组温度场变化和壳体鼓包形变的有效监测。本文的研究工作有望为锂电池组的安全 监测和使用提供可靠的依据。
Summary
锂离子电池是当今最通用的储能技术之一,在新能源汽车、航空航天、无人机、电 网等众多行业和领域被广泛地使用 [1]。这种日益增长的依赖性使得锂电池的可靠和安全 使用比以往任何时候都更加重要,从而促使了准确监控电池安全状态的需求。锂电池安 全隐患通常表现为燃烧和爆炸,而这些表现有一个共同点就是电池内部的热失控,这是 一切锂电池安全问题的根源。当锂电池出现安全问题时,正极会出现活性物质分解、电 解液氧化等反应,这些反应会产生大量的热,电池内部表现为温度异常升高 [2]。除此之 外,一些外部环境(如挤压、刺穿等)引起电池形变也会导致锂电池的安全问题 [3]。换 言之,对锂电池的安全监测可以理解为对电池内部的温度以及形变的监测,并且要求对 电池内部温度与形变测量的精度要尽可能的高。 化时,FBG 的中心波长漂移 Δλ 和温度变化 ΔT 的关系为 [12]: 图 1 (a)双包层光纤结构;(b)封装 FBG 温度传感器;(c)温度应变响应反射谱实时测试装置 Fig. 1.
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