锂离子动力电池低温交流激励产热机理与加热方法研究

The lithium-ion battery has been widely accepted as the energy storage carrier for the electric vehicles（EV）and plug-in hybrid electric vehicles (PHEV).However, the power and energy are substantially lost as the temperature falls. More seriously, low temperature decreases the safety due to the accumulation of the lithium on the surface of negative electrode during discharging. So the poor performance has become the main bottleneck to restrict the spread and application of its technical advantages. In order to provide basic theory and scientific method for systematic innovation to solve the main problems mentioned above, we intend to use high-frequency AC excitation to pre-heating the battery and provide AC waveform, frequency and amplitude selected on the basis of the porous theory..The specific contents include: 1) Analyze the electrode processes and AC impedance at low temperature ,Reveal the lithium metal accumulation process and formation conditions, explore the key parameter which constraints battery low temperature performance and study the coupling relationship between the parameters and temperature.2) Based on the electrode process analysis to reveal the heat mechanism, temperature mechanism and influence of parameters and establish an electrochemical-thermal coupling model. Combined with the coupling model and experiments to provide references of the excitation waveform, frequency and amplitude.3) Design the battery inner temperature on-line estimate model and the AC heating circuit module based on the research foundation and vehicle energy storage system technology.

锂离子电池已被广泛接受成为电动汽车及插电式混合动力汽车的储能载体，低温下电池的枝晶导致安全性大大降低，功率特性变差及效率下降是制约其技术优势发挥和实际应用的客观因素。为解决上述关键问题，本课题基于电池电极过程机理及低温交流阻抗的研究，拟采用高频交流激励的方式，在不产生锂金属堆积的前提下，对EV及PHEV用电池模块进行高效加热，并提供交流电波形、频率及幅值选择依据的基础理论及实现上述交流激励的系统创新的科学方法。具体内容包括：1.低温下研究电池电极过程，揭示微观尺度下低温电极过程及锂金属堆积的形成条件及过程；2.基于电极过程分析交流产热机理、温升过程和参数影响规律，揭示电池交流加热方法产热机理及建立多尺度多域的电池分布式电极-阻抗-热耦合模型。为交流加热参数的选择提供参考依据；3. 建立电池内部温度在线估计模型，进行交流激励电路及自适应控制算法的设计，并提供系统创新的科学方法。

高效快速无损的交流加热是缓解锂离子电池低温问题的重要举措。为此，本项目开展了电池低温下电极动态过程及建模，明晰了电池电极参数随温度变化对阻抗特性的影响规律，为实验现象分析和建立电热耦合产热模型提供了理论基础；揭示了电池交流加热锂沉积条件并探明了交流激励三要素(激励电流、频率、幅值)对电池寿命的影响规律，为确定合适的交流加热激励三要素参数提供了理论依据；研究了电池交流产热机理并建立了电池交流激励下温升过程模型，为交流加热过程中电池内部温度估计提供了基础，对车载交流加热时系统控制策略开发制定具有重要意义；创新性地提出了考虑弛豫效应地电池内部温度实时在线估计方法，为交流加热过程中的温度反馈控制及热安全事故预警等提供了基本手段；开发并验证了针对串联电池组的交流激励系统样机，为指导车载高效、高集成交流加热装置设计提供了技术参考。本项目取得的系列化创新性成果从系统层面回答了锂离子电池低温交流加热关键问题，具有重要的科学价值、应用价值，有望迅速实现技术转化和应用，促进高效快速无损的交流加热的普及。