Sustainable Cathodes for Lithium‐Ion Energy Storage Devices Based on Tannic Acid—Toward Ecofriendly Energy Storage

Abstract

The use of organic materials with reversible redox activity holds enormous potential for next‐generation Li‐ion energy storage devices. Yet, most candidates are not truly sustainable, i.e., not derived from renewable feedstock or made in benign reactions. Here an attempt is reported to resolve this issue by synthesizing an organic cathode material from tannic acid and microporous carbon derived from biomass. All constituents, including the redox‐active material and conductive carbon additive, are made from renewable resources. Using a simple, sustainable fabrication method, a hybrid material is formed. The low cost and ecofriendly material shows outstanding performance with a capacity of 108 mAh g−1 at 0.1 A g−1 and low capacity fading, retaining approximately 80% of the maximum capacity after 90 cycles. With approximately 3.4 V versus Li+/Li, the cells also feature one of the highest reversible redox potentials reported for biomolecular cathodes. Finally, the quinone‐catecholate redox mechanism responsible for the high capacity of tannic acid is confirmed by electrochemical characterization of a model compound similar to tannic acid but without catecholic groups.

Tannin: a new insight into a key product for the bioeconomy in forest regions

“…In early 2021, researchers in Germany reported that it was enough to ball mill tannic acid and porous carbon, easily derived from sucrose, to form a stable composite (C/TAN) showing excellent capacity of 108 mAh g −1 at 0.1 A g −1 and low‐capacity fading 24 . Tannic acid, via the quinone‐catecholate redox mechanism, and porous carbon, through its high surface area and excellent conductivity, are responsible for the high capacity observed.…”

“…Electrochemical performance of C/TAN: charging–discharging test at 0.1 A g −1 (reproduced from ref. 24, with kind permission).…”

“…(b) Ball milling mechanism affording the C/TAN composite (reproduced from ref. 24, with kind permission).…”

“…Replacing the inorganic oxides mentioned above used to manufacture today's LiB cathodes with a readily available organic material such as the tannic acid/carbon composite also mentioned above would not only dramatically lower LiB production costs (an ongoing trend due to massive deployment of LiB production factories in China), 26 but would also lower the market entry costs because the material is readily prepared by the safe and simple milling of two powders 24 …”

“…One such new application of tannin is as biopesticide and plant corroborant, a field pioneered in Italy 20 . Another could be in Li‐ion batteries, as recently demonstrated at laboratory scale in Germany 24 …”