title: All organic sodium-ion batteries with Na₄C₈H₂O₆.
abstract: Developing organic compounds with multifunctional groups to be used as electrode materials for rechargeable sodium-ion batteries is very important. The organic tetrasodium salt of 2,5-dihydroxyterephthalic acid (Na4DHTPA; Na4C8H2O6), which was prepared through a green one-pot method, was investigated at potential windows of 1.6-2.8 V as the positive electrode or 0.1-1.8 V as the negative electrode (vs. Na(+)/Na), each delivering compatible and stable capacities of ca. 180 mAh g(-1) with excellent cycling. A combination of electrochemical, spectroscopic and computational studies revealed that reversible uptake/removal of two Na(+) ions is associated with the enolate groups at 1.6-2.8 V (Na2C8H2O6/Na4C8H2O6) and the carboxylate groups at 0.1-1.8 V (Na4C8H2O6/Na6C8H2O6). The use of Na4C8H2O6 as the initial active materials for both electrodes provided the first example of all-organic rocking-chair SIBs with an average operation voltage of 1.8 V and a practical energy density of about 65 Wh kg(-1).
authors.affiliation: Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin 300071 (China).
authors.forename: Shiwen
authors.initials: S
authors.lastname: Wang
authors.forename: Lijiang
authors.initials: L
authors.lastname: Wang
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Zhu
authors.forename: Zhe
authors.initials: Z
authors.lastname: Hu
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
keywords: batteries; electrochemistry; electrode materials; rocking-chair cell; sodium