The modulation of the discharge plateau of benzoquinone for sodium-ion batteries

p-Benzoquinone (BQ) is a promising candidate for next-generation sodium-ion batteries (SIBs) because of its high theoretical specific capacity, good reaction reversibility, and high resource availability. However, practical application of BQ faces many challenges, such as a low discharge plateau (∼2.7 V) as cathode material or a high discharge plateau as anode material compared with inorganic materials for SIBs and high solubility in organic electrolytes, resulting in low power and energy densities. Here, tetrahydroxybenzoquinone tetrasodium salt (Na 4 C 6 O 6 ) is synthesized through a simple neutralization reaction at low temperatures. The four −ONa electron-donating groups introduced on the structure of BQ greatly lower the discharge plateau by over 1.4 V from ∼2.70 V to ∼1.26 V, which can change BQ from cathode to anode material for SIBs. At the same time, the addition of four −ONa hydrophilic groups inhibits the dissolution of BQ in the organic electrolyte to a certain extent. As a result, Na 4 C 6 O 6 as the anode displays a moderate discharge capacity and cycling performance at an average work voltage of ∼1.26 V versus Na/Na + . When evaluated as a Na-ion full cell (NIFC), a Na 3 V 2 (PO 4 ) 3 ‖ Na 4 C 6 O 6 NIFC reveals a moderate discharge capacity and an average discharge plateau of ∼1.4 V. This research offers a new molecular structure design strategy for reducing the discharge plateau and simultaneously restraining the dissolution of organic electrode materials.