Organic electrode materials with solid-state battery technology

The quest for next-generation sustainable (resource-wise, safe and eco-friendly), high performance (light-weight and energy/power dense) and cost-efficient rechargeable energy storage devices has been catalyzing the research on new battery chemistries. In this research rush, organic electrode materials have ticked many of the wish-list boxes, but there are also a few obstacles to overcome, the two major ones being their intrinsically poor electronic conductivity and instantaneous dissolution into liquid electrolytes. In this critical review, we first provide the readers with a brief account of the various organic material families considered for electrode materials, with their particular benefits and problems. Then, using some basic concepts borrowed from the field of organic electronics we aim to gain a deeper insight into the conductivity of organics in electrochemical systems - an issue little discussed so far. To address the solubility issue we discuss - with some illustrative examples - the benefits and challenges possibly emerging by combining the organic electrodes with a solid electrolyte instead of the conventional liquid electrolyte. As one of the highlights we discuss thin-film microbatteries fabricated using the atomic/molecular layer deposition (ALD/MLD) technique, where ultrathin layers of the LiPON electrolyte are combined with lithium quinone and terephthalate electrodes. Such a thin-film configuration is intriguing in the sense that it does not contain any additives, thus serving as an ideal model system for fundamental studies.