Development of Membrane and Electrolyte to Enable Metal Cathodes for Energy Storage Applications

Abstract

The rapid development of lithium-ion batteries in the past few years is gradually being hindered by the high cost and limited availability of its raw materials on Earth. In this sense, researchers are currently devoting themselves to explore substitutes for current lithium-ion batteries. Metal-metal battery is one of the novel battery systems that rely on the electrochemical redox reactions of two different metal/metal cation pairs, where common abundant metals could potentially be used.

For example, by coupling a Cu metal cathode with a Li metal anode, a 3.3 V battery can be achieved. A Cu-Zn battery will also have a voltage of about 1.1 V. Though, the reversibility of the metal-metal battery is highly limited by the cross-over of metal cations from the cathode to the anode. To overcome such problem and increase Coulombic efficiency of the metal-metal batteries, two types of membranes, one functions by the chemical interaction with the metal cations and another relying on the electrostatic repulsion were developed in this thesis.

While the introduction of a new membrane improves cycle stability, the kinetics of ion transport through the membrane becomes a bottleneck. In this thesis, solvation structure of the electrolyte as well as the interaction between the electrolyte and the membrane were studied to develop a new electrolyte composition to increase power capability of the metal-metal battery.

Kinetics and performances of metal-metal batteries were also dependent on the type of metal used. Various metals such as Cu, Sn, Ni cathodes and Zn, Li anodes were explored in the thesis to understand their differences.

Overall, the electrochemical performance of a metal-metal battery depends on many aspects including the separator, electrolyte, and electrode materials. The research works outlined in the thesis provide a comprehensive understanding of the functions of various battery components in metal-metal batteries, identify issues in the cells, and propose corresponding strategies to address them. The scientific findings presented in the thesis will be valuable for the continued development of the metal-metal battery system.

Date of Award	4 Aug 2023
Original language	English
Awarding Institution	City University of Hong Kong
Supervisor	Jason LAM (Supervisor) & Denis YU (External Co-Supervisor)