This project describes an integrated research and education plan for measuring and enhancing thermal transport through key materials and material interfaces in electrochemical energy storage devices such as a Li-ion cell (battery). Li-ion cells offer excellent energy density and electrochemical performance in multiple applications, including electric vehicles. However, overheating due to poor thermal conduction is a well-known technological barrier, which directly impedes performance and results in severe safety concerns, as shown in recent incidents of fire in aircraft and car battery packs. There is an urgent need to identify and alleviate the fundamental material-level root cause of poor thermal behavior of Li-ion cells. This can potentially transform Li-ion cell performance and safety, but is also particularly challenging due to the highly coupled nature of thermal and electrochemical transport in a Li-ion cell over multiple length scales, and due to the importance of preserving electrochemical performance while improving thermal transport. This work will lay the foundation of microscale thermal engineering of electrochemical energy storage materials for current and future devices. Experimental and theoretical research methods developed in this work will be applicable to several other related engineering systems, such as super-capacitors. Education and outreach initiatives will address learning challenges among undergraduate students, particularly non-traditional "commuter" students and those from under-represented groups.
This proposal addresses scientifically and technologically relevant problems related to poor thermal transport in Li-ion cells, which is a major impediment to performance and safety. A unique test platform capable of in situ, material-level thermal and electrochemical measurements in real time on an operating Li-ion micro-cell will be built. This interdisciplinary research will, for the first time, measure and enhance thermal transport in materials and material interfaces in Li-metal and solid state electrochemical devices through interfacial chemical bridging and microstructural changes. These research thrusts will quantify the nature of microstructure-property-function relationships for key Li-ion materials. Improved cell-level thermal performance due to thermal enhancement of rate-limiting processes will directly result in safe and high performance batteries that will transform the nature of energy conversion, transportation and electronics through applications that are simply not possible with present batteries.