Conjugated dicarboxylate anodes for Li-ion batteries

Present Li-ion batteries for portable electronics are based on inorganic electrodes. For upcoming large-scale applications the notion of materials sustainability produced by materials made through eco-efficient processes, such as renewable organic electrodes, is crucial. We here report on two organic salts, Li2C8H4O4 (Li terephthalate) and Li 2C6H4O4(Li trans-trans-muconate), with carboxylate groups conjugated within the molecular core, which are respectively capable of reacting with two and one extra Li per formula unit at potentials of 0.8 and 1.4 V, giving reversible capacities of 300 and 150 mAhg-1. The activity is maintained at 80°C with polyethyleneoxide-based electrolytes. A noteworthy advantage of the Li2C8H4O4 and Li2C6H 4O4 negative electrodes is their enhanced thermal stability over carbon electrodes in 1M LiPF"6 ethylene carbonate-dimethyl carbonate electrolytes, which should result in safer Li-ion cells. Moreover, as bio-inspired materials, both compounds are the metabolites of aromatic hydrocarbon oxidation, and terephthalic acid is available in abundance from the recycling of polyethylene terephthalate. © 2009 Macmillan Publishers Limited. All rights reserved.