Jing Yan, Liang Yanliang, Gheytani Saman, Yao Yan
Department of Electrical and Computer Engineering and Materials Science and Engineering Program, University of Houston, 4726 Calhoun Rd, Houston, TX, 77204, USA.
Current address: Department of Chemistry and Chemical Biology, Harvard University, 12 Oxford Street, Cambridge, MA, 02138, USA.
ChemSusChem. 2020 May 8;13(9):2250-2255. doi: 10.1002/cssc.202000094. Epub 2020 Mar 12.
Aqueous batteries could be potentially used for grid-scale energy storage owing to the use of nonflammable electrolytes and long cycle life. Recently, quinones have shown examples as redox-active materials in aqueous batteries under either strong acidic or basic conditions. However, a quinone-based battery with a less corrosive electrolyte is still rare. Given that quinone-based batteries are heavily influenced by the pH of electrolytes, we studied the influence of acid dissociation constants (pKa) of hydroquinones on their performance as solid electrode materials. We measured the pKa of anthracene-9,10-diol (AQH ) and benzo[1,2-b:4,5-b']dithiophene-4,8-diol (BDTDH ) from the Pourbaix diagrams of two para-quinone monomers [i.e., anthracene-9,10-dione (AQ) and benzo[1,2-b:4,5-b']dithiophene-4,8-dione (BDTD)]. Subsequently, their polymeric forms [i.e., poly(anthraquinonyl sulfide) (PAQS) and poly(benzo[1,2-b:4,5-b']dithiophene-4,8-dione-2,6-diyl sulfide) (PBDTDS)] were investigated as electrodes in aqueous lithium-ion cells. At pH 13, PAQS demonstrates a low capacity and poor cycle life, whereas PBDTDS shows a capacity of 196 mAh g and fade rates of 0.0038 % per cycle over 4200 cycles, 0.77 % per day over 21 days. The differences in capacity and cycle stability can be explained by the difference of corresponding pKa values. A full cell with the configuration of (-)PBDTDS|2.5 m Li SO (pH 13)|LiCoO (+) shows a voltage of 1.08 V, a capacity of 72 mAh g and ≈99.9 % of Coulombic efficiency for 500 stable cycles.
由于使用了不可燃电解质和长循环寿命，水系电池有可能用于电网规模的储能。最近，醌类化合物已被证明可作为强酸性或碱性条件下水系电池中的氧化还原活性材料。然而，具有腐蚀性较小的电解质的醌基电池仍然很少见。鉴于醌基电池受电解质pH值的影响很大，我们研究了对苯二酚的酸解离常数（pKa）对其作为固体电极材料性能的影响。我们从两种对醌单体[即蒽-9,10-二酮（AQ）和苯并[1,2-b:4,5-b']二噻吩-4,8-二酮（BDTD）]的Pourbaix图中测量了蒽-9,10-二醇（AQH ）和苯并[1,2-b:4,5-b']二噻吩-4,8-二醇（BDTDH ）的pKa。随后，研究了它们的聚合物形式[即聚（蒽醌基硫化物）（PAQS）和聚（苯并[1,2-b:4,5-b']二噻吩-4,8-二酮-2,6-二基硫化物）（PBDTDS）]作为水系锂离子电池电极的性能。在pH为13时，PAQS表现出低容量和较差的循环寿命，而PBDTDS在4200次循环中显示出196 mAh g的容量和0.0038%/循环的衰减率，在21天内每天衰减0.77%。容量和循环稳定性的差异可以通过相应pKa值的差异来解释。配置为（-）PBDTDS|2.5 m Li SO （pH 13）|LiCoO （+）的全电池在500次稳定循环中显示出1.08 V的电压、72 mAh g的容量和约99.9%的库仑效率。
