Rechargeable Batteries Using Robust but Redox Active Organic Radicals

Engineering radical polymer electrodes for electrochemical energy storage

“…Advances in the science and engineering of organic-based solid electrodes are required to overcome the low electronic conductivity and mass density of active materials, and achieve the low-cost high-charge-storage-capacity promise of organic-based electrodes. At present most organic electrodes require large amounts of conductive additives (30-80 wt%) to provide electronic percolation and enable high-rate devices [11,128]. Improvements to electrode fabrication procedures (e.g., ball-milling, solutionprocessing), increased active species conductivity and the use of carbon nanostructures (e.g., graphene) can reduce required carbon loadings and enhance practical performance [35,266,267].…”

“…Specifically, the nitroxide radical group, e.g. 2,2,6,6-tetramethyl-piperidin-1oxyl (TEMPO), has received the most attention because of its rapid redox kinetics and air-stability [128][129][130]. Further, chemical modification (e.g., structural orientation or substituent groups) can be used to maximize the redox potential or create p-or n-type radical polymers [98,[131][132][133][134][135].…”

“…Composition refers to the relative fractions of active material (i.e., radical polymer), conductive carbon, and polymer binder within an electrode. Currently, a large amount of conductive carbon is added to radical polymer electrodes, ranging from 30-80 wt%, due to the poor electronic conductivity of the polymer [11,128]. High amounts of carbon also require relatively high amounts of binder, e.g.…”

Recent Developments and Trends in Redox Flow Batteries

“…Certain classes of stable radicals, most notably nitroxides, are both durable and reactive under specific conditions, and thus are of interest as charge storage materials. Indeed, significant efforts by Nishide and co-workers have focused on developing organic radical batteries based on stable radical monomers tethered to polymeric backbones [91,92]. Efforts by Buhermester et al and Nakahara et al have focused on understanding and exploiting nitroxide-based radicals, typically derivatives of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), as active materials in non-aqueous electrolytes (e.g., for overcharge protection) [93,94].…”

Magnetic and Electric Properties of Organic Nitroxide Radical Liquid Crystals and Ionic Liquids

“…This is the first example detecting the interaction between localized spins and conducting electrons in an organic molecular assembly, i.e., a molecule-based spintronics using not only the charge but also the spin of an electron (Sugawara et al, 2011). Meanwhile, for the last decade the redox properties of NRs have been utilized for the development of environmentally benign organic cathode-active materials for rechargeable batteries with a high energy-density, such as a stable nitroxide polyradical, poly(2,2,6,6-tetramethylpiperidinyloxy methacrylate (4) (Figure 1) (Nakahara, 2002;Oyaizu & Nishide, 2010;Suga & Nishide, 2010). Thus, stable NR structures have been used as the spin source or the redox species to develop metal-free solid-state magnetic materials and spintronic devices, or polymer battery devices, respectively.…”