Optimization of nanostructured organic cathode Li4-p-DOBDA

Details

Supervisors

Vlad, Alexandru ; Proost, Joris ; Filinchuk, Yaroslav

Faculty

Ecole polytechnique de Louvain

Degree label

Master [120] : ingénieur civil en chimie et science des matériaux, à finalité spécialisée

Abstract

Renewable energy and electric vehicles (EVs) play a crucial role in achieving EU’s 2050 goals. Consequently, there is a growing demand for robust energy storage systems. While Lithium-Ion Batteries (LIB) have emerged as a most promising solution due to high energy density and relatively lower energy cost per unit, the exponential surge in demand for Lithium (Li) raises concerns about potential resource depletion, as reserves of Li supplies are not unlimited. Alternative solutions are being explored, particularly those that are abundant, similar, sustainable, safe, cost-effective and can be derived from renewable sources. Organic batteries have garnered significant research interest and momentum in recent years, meeting many of these criteria while offering comparable electrochemical performance that potentially will catch up with commercial LIBs in the future. Among the various organic molecules being considered, an air-stable Li4-p-DOBDA cathode stands out as a viable and attractive option. Synthesized under an inert atmosphere using the Schlenk tube method, this cathode exhibits two-electron redox processes, with an average redox potential of 3.35 V vs. Li+/Li comparable to the commercial Lithium Iron Phosphate (LFP) battery, while having a high theoretical specific capacity of 214.51 mAh/g. The material properties of Li4-p-DOBDA are also evaluated using characterization techniques such as FTIR, SEM and XRD. However, challenges exist that hinder its implementation on a larger scale. Issues related to polarization and solubility lead to rapid capacity fading as the active material gets dissolved during cycling. To mitigate these challenges, the particle size of the cathode material is reduced through ball-milling, resulting in particles ranging from hundreds of nm to 1 m. This particle size reduction increases the contact surface area of the electrode composite, thereby reducing polarization and solubility. Notably, this approach yields improved electrochemical performance, particularly when used in conjunction with 10%Graphene-SP at a frequency of 25 Hz (G-SP 25 Hz). Finally, the potential of the organic cathode extends beyond LIBs, as it is transferrable to the post-LIB system. A preliminary assessment of the material properties and electrochemical performance is conducted for Na4-p-DOBDA, providing insights into the redox phenomena, in comparison with Li4-p-DOBDA, as well as facilitating further investigation of its chemistry and optimization as a viable alternative solution.