Charge/Discharge Properties of Organometallic Batteries Fabricated with Ferrocene–Containing Polymers

A group of ferrocene-containing polymers were synthesized from vinylferrocene, ethynylferrocene and 1,1'-dibromoferrocene, and properties of the formed polymers were examinedto clarify their potential as a new class of cathode-active, charge-storage materials for rechargeable batteries. Vinylferrocene polymerized with 2,2'-azoisobutyronitrile (AIBN) to give a polymer with number-average molecular weights of 2200-5100 g . mol 1 in 12-41% yields, while ethynylferrocene and 1,1' -dibromoferrocene polymerized with Rh catalysts and by step-growth mechanism, respectively, to provide insoluble polymers in 71-96% yields. The capacities of organometallic rechargeable cells fabricated with poly(vinylferrocene), poly(ethynyl-ferrocene), and poly(ferrocene) reached 105, 105, and 95 Ah kg- 1 , respectively. In particular, poly(vinylferrocene) displayed completely reversible charge/discharge processes featuring a constant voltage of around 3.5 V.