Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA.
Chemistry. 2012 Jul 2;18(27):8521-6. doi: 10.1002/chem.201103535. Epub 2012 May 29.
Organosulfur compounds with multiple thiol groups are promising for high gravimetric energy density electrochemical energy storage. We have synthesized a poly(2,5-dimercapto-1,3,4-thiadiazole) (PDMcT)/poly(3,4-ethylenedioxythiophene) (PEDOT) composite cathode for lithium-ion batteries with a new method and investigated its electrochemical behavior by charge/discharge cycles and cyclic voltammetry (CV) in an ether-based electrolyte. Based on a comparison of the electrochemical performance with a carbonate-based electrolyte, we found a much higher discharge capacity, but also a very attractive cycling performance of PDMcT by using a tetra(ethylene glycol) dimethyl ether (TEGDME)-based electrolyte. The first discharge capacity of the as-synthesized PDMcT/PEDOT composite approached 210 mAh g(-1) in the TEGDME-based electrolyte. CV results clearly show that the redox reactions of PDMcT are highly reversible in this TEGDME-based electrolyte. The reversible capacity remained around 120 mAh g(-1) after 20 charge/discharge cycles. With improved cycling performance and very low cost, PDMcT could become a very promising cathode material when combined with a TEGDME-based electrolyte. The poor capacity in the carbonate-based electrolyte is a consequence of the irreversible reaction of the DMcT monomer and dimer with the solvent, emphasizing the importance of electrolyte chemistry when studying molecular-based battery materials.
具有多个巯基的有机硫化合物在高重量能量密度电化学储能方面具有很大的应用前景。我们采用一种新方法合成了聚(2,5-二巯基-1,3,4-噻二唑)(PDMcT)/聚(3,4-乙撑二氧噻吩)(PEDOT)复合正极材料，用于锂离子电池，并在醚基电解液中通过充放电循环和循环伏安法(CV)研究了其电化学性能。通过与碳酸盐基电解液的电化学性能比较，我们发现使用四甘醇二甲醚(TEGDME)基电解液时，PDMcT 的放电容量更高，循环性能也非常有吸引力。在 TEGDME 基电解液中，合成的 PDMcT/PEDOT 复合正极的首次放电容量接近 210 mAh g(-1)。CV 结果清楚地表明，在这种 TEGDME 基电解液中，PDMcT 的氧化还原反应具有很高的可逆性。经过 20 次充放电循环后，可逆容量仍保持在 120 mAh g(-1)左右。由于具有改善的循环性能和非常低的成本，当与 TEGDME 基电解液结合使用时，PDMcT 可能成为一种非常有前途的正极材料。在碳酸盐基电解液中容量较低是由于 DMcT 单体和二聚体与溶剂的不可逆反应造成的，这强调了在研究分子基电池材料时电解质化学的重要性。
