Electrochemically-Induced Fracture of Ionic Conductors: Electrolyzers and Batteries

非技术描述：许多技术和消费应用涉及使用电化学设备，如电池。对于下一代汽车来说，一种燃料是氢气，它通常是通过高温电解制成的。这些设备在运行过程中容易出现故障。更具戏剧性的是最近导致火灾的锂电池故障。据报道，笔记本电脑、手机、滑板和飞机上的电池失效导致火灾的事件层出不穷。即使电解槽不会着火，它们仍然容易发生故障。已报道的大部分研究都是将故障归因于电极破裂、微结构变化和有缺陷的电极等影响。理论研究表明，发生故障的关键部件往往是电解液本身。在某些情况下，通过电解液的电化学传输(离子电流)可能会由于电化学-机械耦合而导致失效，从而导致电解液和器件的电化学断裂。对电池和电解槽失效的根本原因进行了理论和实验研究。了解电化学断裂还有助于设计更耐用的电池，并将意外火灾的可能性降至最低。对锂离子导体和氧离子导体进行了实验研究。对电化学断裂的起因和裂纹扩展速率进行了理论研究。该项目支持一名攻读博士学位的研究生和一名本科生。学生将接受在学术界和电池公司就业的培训。技术细节：虽然已经报道了许多锂电池起火的案例，但对故障的根本原因一直难以理解。众所周知，电解槽在某些情况下会失效。常见的线程是它们在操作过程中出现故障。本项目从理论和实验两个方面研究电解液的电化学诱导断裂，这种断裂会导致器件的最终失效。理论工作考察了电流通过过程中裂纹扩展的发生，在内部产生的载荷下导致断裂。对锂离子导体和氧离子导体进行了实验研究。金属探头嵌在电解液中，端子伸出。电化学诱导的断裂是通过在电解模式下测试样品而开始的。电流和产生的能斯特势的测量提供了关于局部压力和裂纹扩展开始的信息。阻抗谱的测量给出了电化学诱导裂纹扩展的动力学。机电耦合问题的解决提供了一种定量的方法来研究电解液故障的基本原理，这些故障具有与电池起火有关的重要意义。这项工作是及时的，因为手持电子产品和汽车需要更大的电池，而且更加紧迫，以将火灾倾向降至最低。了解电解液在电化学操作下的故障有可能导致更安全的电池。

NON-TECHNICAL DESCRIPTION: Many technological and consumer applications involve use of electrochemical devices such as batteries. For the next generation automobiles, one fuel choice is hydrogen which is often made by high temperature electrolysis. These devices are subject to failure during operation. Even more dramatic are recent failures of lithium batteries that have led to fires. Numerous instances of fires caused by failed batteries in laptops, cell phones, skate boards, and airplanes have been reported. Even though electrolyzers do not catch fire, they are still subject to failure. Much of the reported research has been on attributing failures to effects such as electrode cracking, changes in microstructures, and defective electrodes. Theoretical research demonstrates that the key component that undergoes failure is often the electrolyte itself. The electrochemical transport (ionic current) through the electrolyte under certain situations can cause failure due to the electrochemical-mechanical coupling, which causes electrochemically-induced fracture of the electrolyte and device. Theoretical and experimental work is conducted to investigate the fundamental reasons of battery and electrolyzer failures. Understanding electrochemical fracture also helps design more durable batteries and minimize the propensity to accidental fires. Experimental work is conducted on lithium and oxygen ion conductors. Theoretical work is conducted on understanding the origin of electrochemical fracture and the rate of crack growth. The project supports one graduate student working towards a PhD and one undergraduate student. Students will be trained for employment in academia and battery companies. TECHNICAL DETAILS: Although numerous instances of fires due to lithium batteries have been reported, understanding of fundamental causes of failures has been elusive. Electrolyzers are known to fail under certain conditions. The common thread is that they fail during operation. This project investigates electrochemically induced fracture of the electrolyte which leads to the ultimate device failure, both theoretically and experimentally. Theoretical work examines occurrence of crack growth during the passage of current which leads to fracture under internally generated load. Experimental work is conducted on lithium and oxygen ion conductors. Metallic probes are embedded inside the electrolyte with terminals protruding out. Electrochemically induced fracture is initiated by testing the samples in electrolytic mode. The measurement of current and generated Nernst potential gives information on local pressure and onset of crack growth. Measurement of impedance spectra gives kinetics of electrochemically induced crack growth. Solution to coupled electrical-mechanical problem gives a quantitative approach to investigating fundamentals of electrolyte failures, which have important implications concerning battery fires. The work is timely as larger batteries are needed for handheld electronics and automobiles with added urgency to minimize propensity to fires. Understanding of electrolyte failures under electrochemical operation has the potential to lead to safer batteries.