锂离子电池内部温度无损监测与演变特性

Non-destructive monitoring and evolutionary characterization of internal temperature in lithium-ion batteries

锂离子电池是一种多物理场耦合的电化学储能装置,无损监测电池内部状态信息对于提升电池管理能力至关重要。由于电芯的低热导率以及电池与外界环境的热量交换不充分,导致电池运行时内部温度分布不均、内外温差明显。本文基于一体化功能极片的设计理念,利用S形布局样式的光纤传感器原位监测了NCM523软包电池的内部温度分布并研究了电池老化前后的温度演变规律及热点区域的位置。通过电池循环性能测试证实了光纤传感器在锂离子电池中的无损植入有效性,确定了原位温度监测的可靠性。同时,通过电池拆解表征和测试分析,展示了一体化功能极片在电池循环老化后的表征结果,验证了一体化功能极片具有可解耦光纤信号、无损监测温度、耐腐蚀、可实现电池分布式原位测量等功能。通过分析温度数据,提出利用恒流放电阶段的温升速率作为电池管理的参量,并且证实电池几何中心区域和正极极耳附近区域的温度演变是监测和管理电池的重点。

Lithium-ion batteries,as electrochemical energy storage devices,involve complex multi-physical field coupling,making non-destructive monitoring of their internal state crucial for enhancing battery management capabilities.Due to the low thermal conductivity of cells and insufficient heat exchange between the battery and the external environment,temperature distribution within the cell is uneven during operation,resulting in significant temperature differences between the internal and external regions.This study employs the integrated functional electrode(IFE)concept,utilizing an in situ S-shaped fiber optic sensor to monitor the internal temperature distribution of the NCM523 pouch cell,capturing temperature evolution patterns before and after battery aging and identifying hotspot locations.Results confirm that embedding the fiber optic sensor does not impair the electrochemical performance of the cell during extended cycling,establishing the reliability of in situ temperature monitoring.Post-mortem analysis of the IFE after battery aging reveals its ability to decouple fiber optic signals,monitor temperature without adverse effects on electrochemical performance,resist corrosion,and enable distributed in situ temperature measurement.By analyzing temperature data,this study proposes using the rate of temperature rise during the constant-current discharge stage as a critical parameter for battery management.It highlights that the temperature evolution in the central region of the battery and around the positive electrode tab is crucial for effective battery monitoring and management.