严酷环境条件下锂离子电池及其关键材料的失效机制研究

Due to high energy density and long cycle life, lithium-ion batteries have been widely equipped in portable electronic devices, electric tools, and electric vehicles. In the pat decades, most of researches have been focused on the development of high performance electrode materials. However, few reports can be found in the field of failure analysis for disabled lithium-ion batteries. To build safer batteries, it is necessary to operate a series of electrochemical misuse tests at extreme working conditions. Here, we propose this project to analysis the electrochemical processes, thermal reactions and mechanical behaviors of lithium-ion batteries at extreme high-temperature, extreme low-temperature and harmful radiation. The failure mechanisms can be achieved by building the chain-reaction evolutions from micro-level to macro-level and from inner to outer space. Furthermore, a theoretical prediction for failure behaviors can be reached by building failure models from experimental data. Thus, some of failure behaviors can be effectively suppressed in advance by taking solutions under the guidance of theoretical calculation and experiment analysis.

锂离子电池由于具有高能量密度、长循环寿命等优点而被广泛应用在便携式电子设备、电动工具、电动汽车上，然而，过去大量的研究大都集中在对新型高性能材料的研究开发，而忽视了对电池失效问题的关注，为此，需要对锂离子电池的失效行为进行研究。为了有效增强锂离子电池的耐用性，有必要在严酷环境条件下对锂离子电池进行极端性测试，并分析其内部存在的潜在问题，以获得高安全性的锂离子电池。本项目旨在发展更高效、更安全锂离子电池及其防控机制，拟通过在严酷环境下（极高温、极低温等）对锂离子电池的电化学行为、力学行为和热学行为进行测试和分析，构建一系列微观与宏观、内部与外部的失效演变过程，获取不同情况下电池的失效机制。再结合实验结果建立失效模型，利用理论计算对失效过程进行模拟分析，以达到对锂离子电池失效行为的有效预测，进而给出相应的防控措施。

锂离子电池由于具有高能量密度、长循环寿命等优点而被广泛应用在便携式电子设备、电动工具、电动汽车上，然而，过去大量的研究大都集中在对新型高性能材料的研究开发，而忽视了对电池失效问题的关注，为此，需要对锂离子电池的失效行为进行研究。本项目通过研究锂离子电池在极高温、极低温、极高压、极低压等严酷环境条件下的电化学行为、力学行为和热学行为，提出了锂离子电池两条相互关联的失效演化路径，即界面膜的热诱导分解→电解液分解→材料界面的解离失效的界面失效过程，与正负极颗粒的微观应力引发→宏观颗粒破碎→三维结构崩塌→电极解离的内应力驱动活性材料的失效过程，正是这两条失效路径从内到外的发展引起了局部失效到最终电池宏观失效。基于该失效路径的特点，项目组发现采用氧化物包覆能有效改善正负极等关键材料的结构和热稳定性，进而提升了锂离子电池关键材料的结构和热稳定性，因此，该工作有助于构建更安全的锂离子电池。