Conjugated Tetrathiafulvalene Carboxylates for Stable Organic Lithium Batteries

Organic electrode materials are potential energy storage materials for the next generation lithium batteries. Herein, carboxylate groups are installed to a conjugated tetrathiafulvalene (TTF) platform to yield two compounds, namely lithium tetrathiafulvalene‐dicarboxylate (TTF‐Li2) and lithium tetrathiafulvalene‐tetracarboxylate (TTF‐Li4), as stable anode materials for lithium batteries. The low solubility in the electrolyte, brought about by the carboxylate groups, and high rechargeability ensured by the conjugated TTF platform lead to excellent battery performance. After cycling at a current density of 0.5 C for 120 cycles, a net specific capacity of 108.19 mAh g−1 and 217.55 mAh g−1 is obtained for the TTF‐Li2 and TTF‐Li4 anodes containing 70 wt.% of active materials, corresponding to 61.4 % and 82.0 % of their theoretical capacities, respectively. The density functional theory (DFT) calculation confirms the well‐delocalized charge for both TTF‐Li2 and TTF‐Li4. Therefore, the TTF‐Li2 and TTF‐Li4 are promising anode materials for lithium batteries. Carboxylated tetrathiafulvalenes: Lithium tetrathiafulvalene‐dicarboxylate (TTF‐Li2) and lithium tetrathiafulvalene‐tetracarboxylate (TTF‐Li4) are studied as stable anode materials for lithium batteries. Low solubility in the electrolyte, and high rechargeability lead to excellent battery performance. The well‐delocalized charge for both TTF‐Li2 and TTF‐Li4 were confirmed by DFT calculations.