Advanced Battery Thermal Management Strategies in View of Fast Charging/Discharging

Abstract

This thesis investigates advanced battery thermal management strategies to enable safe and efficient fast charging and discharging of lithium-ion batteries. The growing adoption of electric vehicles and grid-scale energy storage systems has increased the demand for high-performance batteries capable of rapid charging and discharging. However, the rapid charge/discharge processes can lead to excessive heat generation within the batteries, posing challenges related to performance degradation, thermal runaway, and safety concerns.

The thesis first provides a comprehensive review of the state-of-the-art in battery thermal management systems (BTMS) for fast charging/discharging applications. It analyzes the thermal issues associated with rapid battery cycling, including temperature rise, temperature non-uniformity, and thermal runaway. The review covers the development of novel cathode and anode materials to improve fast charging capability, as well as the advancements in various BTMS strategies such as liquid cooling, phase change material cooling, refrigerant-based cooling, and emerging techniques leveraging machine learning.

Building on the literature review, the thesis then presents the design, development, and numerical validation of a novel U-shaped lightweight liquid-cooled BTMS for prismatic lithium-ion battery cells. The system utilizes a U-shaped liquid cooling plate to effectively manage the battery temperature from its lateral and bottom surfaces, enabling weight reduction compared to conventional designs. A machine learning-based regression model using Gaussian process regression is developed to predict the maximum temperature and temperature uniformity of the battery under different operating conditions.

Further, the thesis investigates the numerical optimization of a supercritical CO₂-based BTMS for large-scale battery energy storage systems. The performance of the sCO₂-based BTMS is compared with conventional coolants, and the effects of various design parameters, such as the number of fluid inlets and discharge rates, are analyzed. The study demonstrates the superior cooling capacity and energy efficiency of the sCO₂-based BTMS over other liquid cooling approaches.

To address the challenges of fast charging and discharging, the thesis also explores metallic phase change material (MPCM)-based BTMS, utilizing the high thermal conductivity and low melting point of gallium to effectively regulate battery temperature. The integration of liquid minichannels within the MPCM layer is shown to enhance heat dissipation and reduce the system weight.

Finally, the thesis presents experimental investigations on the development of gallium-based and hexagonal boron nitride (h-BN)-based composite phase change materials (CPCMs) for BTMS applications. The high thermal conductivity and low melting point of gallium, combined with the reinforcing effect of h-BN, enable efficient thermal management and improved safety during fast battery cycling.

The findings of this comprehensive research work provide valuable insights and guidelines for the design, optimization, and implementation of advanced BTMS to support the widespread adoption of lithium-ion batteries in fast charging/discharging applications, such as electric vehicles and grid-scale energy storage systems.

Date of Award	10 Sept 2024
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Jiyun ZHAO (Supervisor)