MODULATING LITHIUM SUPEROXIDE STABILITY FOR HIGH-PERFORMANCE LI-O2 BATTERIES

Abstract

Li-O2 battery has a high theoretical specific energy density of 3500 Wh kg-1 and practical energy storage capacity of 500-1000 Wh kg-1, which can exceed the limits of Li-ion batteries (∼300 Wh kg−1cell) and meet the needs of the future electrochemical power sources. Li2O2 as the discharge product can manifest by solution-based mechanism or surface-based mechanism, controlled by the solubility of lithium superoxide (LiO2) intermediate. However, superoxide radical is easy to launch a nucleophilic attack towards solvent. It can also diffuse to lithium metal anode, cracking the solid electrolyte interphase (SEI) layer and resulting in the corrosion of the Li anode and the continuous degradation of the electrolyte. Therefore, stabilizing superoxide radical is paramount to enhance the performance of Li-O2 batteries. In this thesis, we propose several approaches, such as employing a kind of organometallic RMs, non-redox additive and cathode modification, to stabilize O2- and achieve high-performance of Li-O2 battery.