Redox-active radical polymers for organic-based energy-storage devices

Emerging technologies with plastic-based flexible electronic devices have evoked keen interest in exploring next-generation flexible and printable power sources. We focused on durable, but highly redox-active property of organic radical molecules, and have developed a new class of redox polymers for electrode-active, charge-storage materials in a rechargeable battery. Radical polymers bearing a high density of unpaired electrons in a pendant, non-conjugated fashion on each repeating unit provided a rapid, reversible, and quantitative redox behavior in an electrode form. Careful selection of radicals (TEMPO, galvinoxyl, and nitronylnitroxide, etc.) produced remarkably reversible p- and n-type redox couples, which lead to the totally organic-based rechargeable batteries. The power-rate performance of these cells was excellent (a few seconds full charging/discharging), and organic polymer-based electrodes also allowed the fabrication of a flexible, paper-like, and transparent rechargeable energy-storage device. Microphase-separated radical-containing block copolymers and electrospun radical fibers toward new electronics applications will be also discussed.