Poly(tetrahydrobenzodithiophene): High discharge specific capacity as cathode material for lithium batteries

A novel thioether containing conjugative polymer, poly(tetrahydrobenzodithiophene) (PTBDT), with high discharge specific capacity as the cathode material for lithium batteries, has been synthesized chemically. The polymer has been characterized by elemental analysis, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The cyclic voltammogram of the polymer shows multiple redox peaks. The charge–discharge tests show stable discharge specific capacity about 560 mAh g−1 and the maximal capacity of 820 mAh g−1, and discharge voltage about 2.3 V. The results indicate that the thioether bonds of the polymer are involved in the electrode reaction. It is tentatively proposed that the thioether cations are formed during the redox reaction on the cathode. The reversible redox reaction on thioether bonds that is a multi-electron process offers a high specific capacity, and low discharge voltages.