Potential Tuning in the Benzenedicarboxylate System for Improved Organic Negative Electrodes

Abstract

Lithium-ion batteries (LIBs) represent one of the most successful battery chemistry with a range of applications starting from small portable electronic devices to advanced electric vehicles. The increasing demands concerning these large-scale applications have generated intense requirements of improved safety, low costs and of course high energy densities. Anode materials generally used in commercial LIBs, i.e. carbonaceous materials, have a very low operating potential (~ 0.1 V vs. Li+/Li) which cause some safety and cost issues. As an alternative, several anode materials have been proposed, such as spinel lithium titanate (Li4Ti5O12) which can operate at potentials of 1.0-1.6 V vs. Li+/Li, this fact leading to a decrease of the cell voltage, or such as Si and SnO2, which are confronted to huge volume variation and structural reorganization during charge-discharge process. In order to achieve the required improvements, anode materials must operate at an intermediate operating potential (0.5-1.0 V vs. Li+/Li). In addition there is a growing interest in designing greener LIBs. In this context, organic carboxylate-based derivatives have been considered as promising materials for the next generation of such greener LIBs due to their structure based on relatively naturally abundant atoms like C, H, O or N, their possible flexible molecular design, ease of recyclability and especially their operating potential allowing to substitute copper-based current collector by aluminum, thus inducing a drastic cost and weight reduction. We will present an electron-donating substitution approach with the aim to decrease the operating redox potential in benzenedicarboxylate systems. More precisely, dilithium DiMethylTerepthalate compound (Li2-DMT) was synthesized, fully characterized and evaluated electrochemically as an anode material for Li-ion storage system. This new carboxylate-based material shows promising electrochemical performance, noticeably a stable cycling performance, high thermal stability and an operating potential of 0.65 V vs. Li+/Li, (i.e., -110 mV in comparison with Li terephthalate). Figure 1