On-chip electrochemical mass spectrometry to probe lithium ion battery degradation

该项目的目的是开发一种新的电化学质谱技术，可以探测锂离子电池降解症状的气体演化。电化学质谱（EC-MS）能够测量电化学系统中的挥发性物质，作为系统运行的函数。锂离子电池会释放出气体作为其退化的症状（例如，当锂离子电池电解质分解时产生二氧化碳，当锂离子电池阴极达到深充电状态时产生O2）。SpectroInlets最近开发了一种新的EC-MS技术，用于水溶液电化学。这种新型的EC-MS使用微加工膜芯片来控制挥发性物质从液体电化学环境转移到质谱仪的真空中。该技术克服了与传统EC-MS技术相关的许多问题，例如差分电化学质谱（dem），实现了更多的时间分辨率和灵敏度测量。该项目旨在进一步发展这种新的EC-MS技术，使其适用于锂离子电池中挥发性物质的测量，锂离子电池的电解质是非水的。然后，它将使用这种技术来深入了解锂离子电池降解的机理细节，重点是使用LiNiMnCoO2作为阴极的电池。通过加深对锂离子电池气体行为的理解，并将这些发现与整个法拉第研究所使用的其他互补表征技术相关联，可以更好地理解锂离子电池中发生的复杂化学反应。随后的洞察将使我们能够改进对电池寿命的预测，并使我们能够设计出更耐用的电池。

The aim of this project is to develop a novel electrochemical mass spectrometry technique that can probe gas evolution that is symptomatic of lithium ion battery degradation. Electrochemical mass spectrometry (EC-MS) enables the measurement of volatile species in electrochemical systems as a function of the systems' operation. Lithium ion batteries evolve gases as a symptom of their degradation (for example CO2 when lithium ion battery electrolytes break down, or O2 when lithium ion battery cathodes reach a deep state of charge). A new EC-MS technique has recently been developed for use in aqueous electrochemistry by SpectroInlets. This new type of EC-MS uses a micro-fabricated membrane chip to control the transfer of volatile species from the liquid electrochemical environment to the vacuum of a mass spectrometer. This technique overcomes many of the issues associated with traditional EC-MS techniques, such as differential electrochemical mass spectrometry (DEMS), enabling more time resolved and sensitive measurements. This project aims to further develop this new EC-MS technique to make it suitable for the measurement of volatile species in lithium ion batteries, whose electrolytes are non-aqueous. It will then use this technique to gain insight into the mechanistic details of lithium ion battery degradation with a focus on batteries that employ LiNiMnCoO2 as their cathodes. Through deepening the understanding of lithium ion batteries' gassing behaviour, and correlating the findings with other complimentary characterisation techniques used throughout the Faraday Institution, the complex chemistry that takes place in lithium ion batteries can be much better understood. The ensuing insight will allow us to improve our predictions of battery lifetimes and enable us to design more durable batteries.