A Conjugated Sulfide-Polymer Battery with Variable Capacitance Controlled by Redox Reaction

A new conjugated sulfide-polymer battery with variable capacitance is proposed as a new type of battery with increased capacity. A sulfur composite material (PNVS450) was prepared by calcinating a mixture of poly(2,6-naphthalene-vinylene) and sulfur. Elemental analysis and Raman spectroscopy indicated that PNVS450 has a conjugated sulfide-polymer structure in which naphthalene rings are linked together by dithienoacene structures. Cyclic voltammetry revealed that the capacitance of PNVS450 was significantly changed by redox reaction, which confirms that the basic concept of a battery with variable capacitance applies to the conjugated sulfide-polymer battery. PNVS450 exhibited a large capacity of more than 0.9 Ah/g, which was larger than the capacity estimated from the sulfur content. Moreover, the battery showed not only a high energy density, but also a high power density in a short time period even in a low state-of-charge, due to the unique properties arising from hybridization of a battery and a capacitor.