Characterization, Modeling, And Thermal Management Of High-Performance Lithium Batteries

Lithium-ion (Li-ion) batteries, as one of the most advanced commercial rechargeable batteries, play a crucial role in modern society as they are extensively used in portable electronic devices. Nevertheless, the limited electrochemical performance and poor thermal management systems of Li-ion batteries have hindered the expansion of their future applications. In search of alternative electrode materials to develop a battery with higher electrochemical performance, lithium (Li) metal has attracted much attention as an ideal alternative anode material due to its high specific capacity and lowest redox potential. However, needle-like Li dendritic growth causes severe safety concerns and thus prohibits practical applications of the Li metal anode. Furthermore, the high sensitivity of Li-ion batteries to abusive operations requires a sophisticated battery management system (BMS) as well as a battery thermal management system (BTMS), especially for automobile applications. In this thesis, the fundamentals of Li-ion batteries and common research strategies to enhance the electrochemical performance of Li-ion batteries are first introduced. The challenges of next-generation Li metal batteries, namely the undesirable Li dendritic growth, is then discussed, followed by introduction of an efficient theoretical model to investigate the fundamentals of Li dendritic growth, the phase-field method (PFM). Black metallic titanium (Ti) foils covered with porous nanorod arrays are proposed as a dendrite-free Li metal anode. The porous Ti nanorod arrays provided numerous heterogeneous nucleation sites, significantly contributing to cycling stability and reversibility: discharge/charge voltage overpotentials of ~8 mV and a Coulombic efficiency of 100 % successfully remained for 1,400 cycles at a current density of 1 mA/cm2 and a capacity of 1 mAh/cm2. Furthermore, the black metallic Ti can be potentially used in aerospace and solar industries owing to its outstanding ability to absorb light, mechanical robustness, and high corrosion resistance. After the introduction of the Ti nanorods, common methods to model a proper BMS are discussed. Moreover, BTMSs for large-scale Li-ion batteries were designed and simulated by using the ANSYS Fluent. An active cooling system was incorporated into the BTMSs to successfully dissipate the enormous amount of heat generated in a battery cell and maintain the operating temperature within the optimal temperature range. It was shown that the uniform temperature distribution was also achieved by modulations of the inlet temperature and velocity. This thesis provides a deep insight into characterization, modeling, and thermal management methods to improve the electrochemical performance of Li batteries.