Extensive research has been conducted to develop advanced lithium ion battery (LIB) technologies to meet the demands of the ground transportation industry for LIBs with higher energy and power densities, lower cost, and safer operation. In addition to the development of advanced materials for the anode, cathode, and electrolyte, the structure of the electrodes at the micro- and nano-scales also plays a critical role in determining the performance of a LIB because the electrode?s composite matrix must be designed to provide both electron and lithium ion transportation, which eventually affects the LIB?s voltage, specific capacity, and discharge/charge rate. Currently, a fundamental understanding of the impact of an electrode?s microstructure on LIB performance is still lacking due to the inhomogeneity, complexity, and three-dimensional (3D) nature of the electrode?s microstructure. In this study, a novel approach is proposed to gain greater understanding of the microstructure of the electrode and its impact on the LIB?s physical and electrochemical performances when using liquid electrolytes as well as solid electrolytes (all-solid LIBs). The knowledge gained in this study is expected to help identify the optimal conditions of the composite electrode?s components and microstructure that will yield compact and safe LIBs with high energy and power densities.
This research project takes a unique, interdisciplinary approach using experimental and theoretical analysis tools from the areas of electrochemistry, nanotechnology, transmission x-ray microscopy, material science, and numerical modeling. This work is expected to establish the engineering and scientific foundation for safe and high power/energy density LIBs. To achieve such an objective, the research efforts will first focus on the fundamental understanding of the porous microstructure of the composite electrode and its impact on the electrochemical performance of liquid electrolyte LIBs, followed by exploration into the impact of the electrode?s microstructure on all-solid LIB performances. X-ray nano-computed tomography (nano-CT) with sub-100 nm resolution will be employed to obtain the 3D microstructure of the LIB electrodes. For the first time, synchrotron x-ray nano-CT will be attempted to perform microstructural characterization of the composite electrode and to identify the particle/particle interface in all-solid LIBs. Both liquid electrolyte and all-solid LIB cells with finely tuned microstructure will be designed, fabricated, and characterized in the PIs? labs. A rich array of knowledge will be obtained through systematic experiments regarding the effects of various factors in the LIB electrodes. A comprehensive mathematical model and simulation framework based on the finite volume method will be established to reveal the physical and electrochemical processes in the electrode. The experimental and numerical results will be used to establish the correlations between the LIB?s performance and the electrode microstructure.
The successful implementation of this research would directly facilitate the improvement of current LIBs that use liquid electrolytes and the development of next generation all-solid LIBs. The scientific and engineering knowledge gained from this project will improve battery capability allowing for the widespread use of environmentally sustainable energy sources, especially in ground transportation. Graduate and undergraduate students will gain critical hands-on research experience through this project. Summer camps will provide local high school students and K-12 teachers a unique opportunity to explore the interdisciplinary fields of advanced battery technologies and renewable energy.
