Utilization of Polyacetylene, (CH)_x, in the Fabrication of Rechargeable Batteries

Abstract

Polyacetylene, (CH)_x, is the first example of a covalent organic polymer which may be chemically doped either p- or n-type to give a series of semiconductors and ultimately “organic metals”.¹ The electrical conductivity can be varied over twelve orders of magnitude depending on the dopant concentration.¹ Detailed studies have shown that a semiconductor-metal transition occurs at dopant concentrations near 1 mole percent. In the metallic range, (1–10 mole percent) the conductivity increases at a relatively slow rate up to a value of ~10³ ohm⁻¹cm⁻¹ at room temperature. We have shown previously that ~0.1 mm thick films of (CH)_x may also be controllably doped electrochemically in a very simple, rapid procedure, either in aqueous or non-aqueous solution, through the semiconducting to the metallic regime.² Thus, the use of aqueous KI solutions or CH₂Cl₂ solutions of, e.g., [(n−C₄H₉)₄ N]⁺[C10₄]⁻, [(n−C₄H₉)₄N]⁺[AsF₆]⁻, etc. yield flexible, golden-silvery films of [CHI_0.07]_x (σ_25°C= 9.7 ohm⁻¹cm⁻¹), [CH(C10₄)_0.0645]_x (σ_25°C=970 ohm⁻¹cm⁻¹), and [CH(AsF₄)_0.077]_x (σ_25°C=553 ohm⁻¹cm⁻¹), respectively. In the doped state, the polyacetylene is believed to exist as the stabilized polycarbonium ion, (CH^+y)_x, with the corresponding number of monovalent counter anions such that the overall composition is [(CH^+y)A ⁻_y ]_X.¹