Experimental study on flammability limits of electrolyte solvents in lithium-ion batteries using a wick combustion method
Experimental study on flammability limits of electrolyte solvents in lithium-ion batteries using a wick combustion method
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DOI：
10.1016/j.expthermflusci.2019.109858
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发表时间：
2019-12-01
影响因子：
3.2
通讯作者：
Fujita, Osamu
中科院分区：
文献类型：
--
作者：
Guo, Feng;Hase, Wataru;Fujita, Osamu
为了定量测定锂离子电池中有机电解液溶剂的可燃极限，提出了一种独特的灯芯燃烧系统，并结合蜡烛火焰的极限氧浓度（O2），命名为灯芯燃烧法。通过控制毛细扩散火焰外流的氧氮比，实验确定了电解质溶剂的可燃极限。为了在特定条件下提供可重复的结果，研究了轴向流速、暴露的芯长度和点燃后经过的时间对芯燃烧的影响，并选择了合适的实验条件用于进一步的应用。为了验证芯吸法在可燃性评价中的可靠性，进行了与其他可燃性性质（闪点、自燃温度、燃烧热和其他类型的可燃性）的相关性分析。然后应用芯吸法来量化混合溶剂的可燃性。线性碳酸酯和环状碳酸酯的混合溶剂中，体系的芯吸率随混合比呈线性变化，而碳酸酯-醚类混合溶剂中，体系的芯吸率随混合比呈非线性变化。为了评价有机磷化合物（OPCs）作为电解质溶剂添加剂的阻燃效果，进行了一系列试验。结果表明，少量的OPC具有显著的阻燃效果，但随着OPC添加量的增加，阻燃效果下降。四个OPC的有效性也得到了认可。研究结果为电解质溶剂的燃烧极限提供了有价值的信息，为电解质的设计提供了参考。
To quantify the flammability limits of organic electrolyte solvents used in lithium-ion batteries, a unique wick combustion system was developed in conjunction with limiting oxygen concentration (LOC) of candle-like flame, named wick-LOC method. By controlling the oxygen-nitrogen ratio of external flow of the wick diffusion flame, the flammability limits (LOC) of electrolyte solvents were determined experimentally. To provide reproducible results under specified conditions, the effects of axial flow velocity, exposed wick length and elapsed time after ignition on the wick-LOC were studied, and the proper experimental conditions were selected for further applications. To validate the reliability of wick-LOC in flammability evaluation, correlation analyses to other flammability properties (flash point, auto-ignition temperature, the heat of combustion and other types of LOC) were conducted. The wick-LOC method was then applied to quantify the flammability of mixed solvents. The linear changes of wick-LOC with mixing ratios were found in the mixture of linear and cyclic carbonates, while the non-linear trends were found in carbonate-ether mixed solvents. To evaluate the flame-retardant effectiveness of organophosphorus compounds (OPCs) as additives in electrolyte solvents, a series of tests were conducted. Results showed that small amounts of OPCs had significant flame-retardant effects, but the efficiency decreased with the higher OPC additions. The effectiveness of four OPCs was distinguished as well. The results of this work provided valuable information about the flammability limits of single and mixed electrolyte solvents, and it may be useful for designing electrolyte balanced in both performance and safety.