CAREER: Predicting battery lifetime from direct measurements of inter-electrode communication

用于车辆运输和可再生电网存储的先进锂离子电池可以提高国内能源安全，但在成本和电池寿命方面的性能差距限制了使用。电池失效的主要原因是设备内部难以量化和理解的不良化学副反应。由于缺乏基本的理解，工程师们不太能够设计出能够长时间承受副反应的材料和设备。因此，到目前为止，工程师主要依靠经验故障测试，这增加了开发新技术的时间和成本。这个基础研究项目采用新方法直接测量影响电池寿命和性能的副反应率。有关反应速率的信息将用于建立预测电池寿命的系统模型。研究结果将使研究人员能够设计出寿命更长的材料，并比传统方法更快地预测设备故障。该项目的教育效益包括在电池科学、反应堆设计和传输建模方面对研究生和本科生的研究人员进行培训。PI还与西费城当地的高中和中学合作，通过实际操作和适合年龄的项目介绍电力和电池设计原理。电池电极界面的研究已经进行了很长时间，但即使是它们的基本工作原理也没有得到充分的解释。这个项目使用了两个关键的创新。首先，一种新型的微反应器控制电极之间的化学通信，从而在保持与非水电池相关的环境的同时，实现明确的反应物和产物的传输。该功能实现了第二个创新：专注于测量影响电池性能的电化学速率常数、扩散系数和电阻率。这些测量是通过电化学发生器-集电极实验来实现的，类似于电催化中的旋转环盘电极。四电极测量分离的现象，以确定反应如何依赖于因素，如电池电位和电解质添加剂。该方法广泛适用；本文工作的重点是高压尖晶石LiNi0.5Mn1.5O4 （LNMO）。确定电荷转移机制将指定电解质溶剂和添加剂的材料参数，而测量薄膜溶解和生长的反应速率将使基于物理的电池模型能够预测系统寿命。该项目使基于物理的模型能够根据测量的反应参数预测电池寿命。这些模型可以识别材料和系统级别的方法，以防止电池故障，并在不增加成本的情况下最大化使用寿命和性能。

Advanced lithium-ion batteries for vehicle transport and renewable electricity grid storage applications could improve domestic energy security but performance gaps in cost and battery lifetime limit use. The main cause of battery failure is undesirable chemical side reactions within the device that are difficult to quantify and to understand. Because of the lack of fundamental understanding, engineers are less able to design materials and devices that can withstand side reactions for longer times. As a result, to date, engineers mainly have to rely on empirical failure tests that increase the time and cost of developing new technology. This fundamental research project applies new methods to directly measure side reaction rates that impact battery lifetime and performance. Information about reaction rates will then be used to build system models that predict battery lifetime. The results will allow researchers to design materials that last longer and to predict device failure much more rapidly than traditional methods. The educational benefits of the project include graduate and undergraduate researcher training in battery science, reactor design, and transport modeling. The PI has also partnered with local high schools and middle schools in West Philadelphia to introduce principles of electricity and battery design using hands-on, age appropriate projects. Battery electrode interfaces have been studied for a long time, but even their basic workings have not been sufficiently explained. This project uses two critical innovations. First, a novel microreactor controls chemical communication between electrodes, resulting in well-defined transport of reactants and products while maintaining an environment relevant to nonaqueous batteries. This feature enables the second innovation: a focus on measuring the electrochemical rate constants, diffusivities, and resistivities that impact battery performance. These measurements are accomplished by amperometrically detecting reaction products with electrochemical generator-collector experiments, analogous to the rotating ring disk electrode in electrocatalysis. The four-electrode measurements separate phenomena in order to determine how reactions depend on factors like cell potential and electrolyte additives. The approach is broadly applicable; the focus of this work is the high-voltage spinel LiNi0.5Mn1.5O4 (LNMO). Identifying the mechanisms of charge transfer will specify material parameters for electrolyte solvents and additives, while measuring the reaction rates of film dissolution and growth will enable physics-based battery models to predict system lifetime. This project enables physics-based models to predict battery lifetime from measured reaction parameters. Such models can identify material- and system-level approaches to prevent battery failure and maximize lifetime and performance without additional cost.