基于单体特征参数差异的电池组热特性和热一致性研究

doi:10.19799/j.cnki.2095-4239.2025.0127

摘要/Abstract

摘要：

锂电池组内单体特征参数(SOC、容量与内阻)的差异通过电-热耦合作用可能导致电池组的热分布不均，影响其性能和安全。本文考虑了锂电池在不同温度和放电深度下的动态特性，构建了电池组的二阶RC等效电路-热耦合模型，通过数值模拟分析了单体SOC、容量和内阻不一致性对并联和串联电池组热特性的影响，最终量化了不同连接模式下电池组的能量释放能力、发热率及温度分布差异。研究结果显示，SOC不一致时，并联电池组因自平衡效应释放能量379.575 Ah，高于串联电池组的366.024 Ah，但其发热率标准差和最高温度标准差分别为2.265 W和0.62 ℃，显著高于串联电池组的0.475 W和0.275 ℃，表明串联结构在热一致性上更具优势。容量不一致时，并联电池组因支路电流差异导致发热率波动更大，其温度标准差为0.421 ℃，较串联的0.233 ℃高0.188 ℃，且最大温差分别为1.222 ℃和0.670 ℃，进一步凸显串联的热均匀性。内阻不一致时，串联电池组平均温度为33.233 ℃，略高于并联的33.204 ℃，但其温度标准差和发热率标准差则为0.19 ℃和0.097 W，均低于并联的0.215 ℃和0.405 W，说明串联模式能有效抑制内阻差异引发的热不均衡现象。进一步量化对比表明，SOC不一致对热一致性的影响最为显著，并联与串联的发热率最大差值分别为6.499 W和1.261 W；容量不一致导致并联电池组最高温度差达到1.222 ℃，为串联的1.8倍；内阻不一致下，串联电池组温度标准差仅为并联的88%。研究结论表明，串联电池组在单体特征参数差异下均表现出更优的热一致性，而并联模式虽能够释放更多能量，但需通过强化热管理以应对更高的温度波动风险。本研究为电动汽车电池组热模型优化及冷却系统设计提供了关键数据支撑，对提升电池安全性与寿命具有重要参考价值。

关键词: 锂离子电池组, 热特性, 热一致性, 等效电路-热模型

Abstract:

Variations in the characteristic parameters of individual cells within a lithium-ion (Li-ion) battery pack-such as state of charge (SOC), capacity, and internal resistance-can lead to nonuniform thermal distribution due to electrothermal coupling, thereby affecting the overall performance and safety of the pack. This study investigates the dynamic behavior of lithium batteries at different temperatures and depths of discharge, and establishes a second-order RC equivalent circuit-thermal coupling model to examine how inconsistencies in SOC, capacity, and internal resistance influence the thermal behavior of series- and parallel-connected battery packs through numerical simulations. The study quantifies disparities in energy release, heat generation, and temperature distribution across various connection configurations. Results show that, under SOC inconsistency, the parallel-connected pack releases 379.575 Ah due to the self-balancing effect-higher than the 366.024 Ah released by the series-connected pack. However, the standard deviation of the heat generation rate and maximum temperature deviation in the parallel configuration are 2.265 W and 0.62 ℃, respectively, which are significantly greater than those in the series configuration (0.475 W and 0.275 ℃), indicating superior thermal consistency in the series-connected arrangement. For capacity inconsistency, the parallel configuration exhibits greater fluctuations in heating rate due to uneven branch currents, with a temperature standard deviation of 0.421—0.188 ℃ higher than that of the series-connected pack (0.233 ℃). The maximum temperature difference reaches 1.222 ℃ in the parallel configuration, compared to 0.670 ℃ in the series, further highlighting the enhanced thermal uniformity of the series layout. Under internal resistance inconsistency, the average temperature of the series-connected pack is marginally higher (33.233 ℃) than that of the parallel configuration (33.204 ℃), yet the standard deviations of temperature and heat generation rate in the series-connected pack (0.19 ℃ and 0.097 W) remain lower than those in the parallel-connected one (0.215 ℃ and 0.405 W). This suggests that the series configuration effectively mitigates thermal imbalance induced by internal resistance variations. Further quantitative comparison reveals that SOC inconsistency has the most pronounced effect on thermal consistency, with maximum differences in heating rate reaching 6.499 W in the parallel configuration and 1.261 W in the series. Capacity inconsistency leads to the largest temperature difference in the parallel pack (1.222 ℃), which is 1.8 times greater than that in the series. For internal resistance inconsistency, the temperature standard deviation in the series configuration is only 88% of that in the parallel. In conclusion, series-connected battery packs exhibit better thermal consistency under parameter inconsistencies, while parallel-connected packs offer greater energy output but demand more robust thermal management to mitigate temperature fluctuations. These findings provide a quantitative foundation for optimizing thermal models and designing cooling strategies in electric vehicle battery systems, thereby enhancing both safety and operational longevity.

Key words: Li-ion battery packs, thermal characteristics, thermal consistency, equivalent circuit-thermal model

中图分类号:

TM 911

张腾, 常国峰. 基于单体特征参数差异的电池组热特性和热一致性研究[J]. 储能科学与技术, 2025, 14(8): 3194-3206.

Teng ZHANG, Guofeng CHANG. Thermal characterization and thermal consistency study of battery packs based on differences in monomer characteristic parameters[J]. Energy Storage Science and Technology, 2025, 14(8): 3194-3206.

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参数	数值
尺寸	148 mm×40 mm×91 mm
放电截止电压/V	2.8
充电截止电压/V	4.2
额定电压/V	3.75
额定容量/Ah	70
质量/g	1300
比热容/[J/(kg·K)]	968.3

连接方式	能量释放/Ah	平均发热率/W	最大发热率差异/W	发热量的最大标准差/W	放电后的平均温度/℃	放电后的最高温度/℃	最大温差/℃	温度的最大标准差/℃
并联	379.575	2.670	6.499	2.265	32.997	33.319	1.778	0.620
串联	366.042	2.601	1.261	0.475	32.567	32.898	0.767	0.275

连接方式	能量释放/Ah	平均发热率/W	最大发热率差异/W	发热量的最大标准差/W	放电后的平均温度/℃	放电后的最高温度/℃	最大温差/℃	温度的最大标准差/℃
并联	419.008	2.645	1.388	0.476	33.232	33.886	1.222	0.421
串联	415.38	2.585	1.133	0.431	32.780	33.102	0.670	0.233

连接方式	能量释放/Ah	平均发热率/W	最大发热率差异/W	发热量的最大标准差/W	放电后的平均温度/℃	放电后的最高温度/℃	最大温差/℃	温度的最大标准差/℃
并联	418.717	2.636	1.436	0.405	33.204	33.469	0.578	0.215
串联	420	2.640	0.262	0.097	33.233	33.467	0.512	0.190