DESIGNING NEW ELECTROLYTE ADDITIVES FOR BETTER LITHIUM-ION BATTERY PERFORMANCE AND OVERCHARGE PROTECTION

摘要

As an alternative energy source, lithium-ion batteries (LIBs) have become increasingly important with a wide range of applications in industry, and many international companies are investing in this big project. The aim of this study is to overcome the safety and capacity limitations of lithium-ion power sources by synthesizing electrolyte additives. Overcharge usually takes place when the current is forced through a cell, and the charge delivered is above its charge storing capability; this can lead to the chemical and electrochemical reaction of the battery's components, rapid temperature increase, self-accelerating reactions and finally, explosion. Overcharge protection additives may be classified as redox shuttles, which reversibly protect the cell from overcharging, or shutdown additives, which permanently terminate cell operation. The main objective of this study is to find new additives that will improve the safety behaviour of lithium-ion power sources, specifically to synthesize novel boronate and siloxane derivatives, based on theoretical (molecular modelling) studies of the HOMO-LUMO energies of these derivatives with respect to their expected electrochemical properties such as electrode potentials compared to those of the commonly used electrolyte solvents. Our first results will be reported. The University of Venda and the National Research Foundation are thanked for generous financial support, and SASOL is thanked for a fellowship for AWB.