Synthesis of 1,4-benzoquinone dimer as a high-capacity (501 mA h g−1) and high-energy-density (>1000 Wh kg−1) organic cathode for organic Li-Ion full batteries

The organic cathodes with high specific capacity are highly desirable to fabricate high-specific-energy-density organic Li-ion full cells. Herein, we initially propose the long-term plan for the systematic synthesis of the oligomer family of 1,4-benzoquinone (BQ), which can possess theoretical specific capacity above 500 mA h g −1 . As a start, the dimer of 1,4-benzoquinone (2,2′-bis-(1,4-benzoquinone), BBQ) is synthesized, which can realize the specific capacity of 501 mA h g −1 and the average discharge potential of ~2.5 V (vs. Li + /Li). Even facing the dissolution problem, BBQ can deliver average specific capacities of ~190 mA h g −1 during 3000 cycles at 500 mA g −1 and ~120 mA h g −1 during 8000 cycles at 2 A g −1 in Li-ion half cells. Afterwards, the all-organic Li-ion full cells are fabricated by using the reduced state (Li 4 TP) of lithium terephthalate (Li 2 TP) as the starting anode and BBQ as the starting cathode. Delightfully, the resulting Li 4 TP-BBQ Li-ion full cells can realize the specific capacity of 316 mA h g −1 cathode in the 1st cycle (500 mA g −1 ). Meanwhile, average specific capacities of ~98 mA h g −1 during 1000 cycles can be fulfilled (500 mA g −1 ). The results of the Li 4 TP-BBQ Li-ion full cells are among the best all-organic Li-ion full batteries reported to date.