High‐Power Electrochemical Energy Storage System Employing Stable Radical Pseudocapacitors

Abstract

The development of electrical energy storage devices that can operate at high charge and discharge rates is fundamentally important, however although electrochemical capacitors (ECs) can charge and discharge at high rates, their electrochemical storage capacity remains an order of magnitude lower than that of conventional lithium-ion batteries. Novel pseudocapasitors are developed, based on the stable persilyl-susbtituted free radicals of the heavy group 14 elements, (tBu2 MeSi)3 E(.) [E=Si (1), Ge (2), and Sn (3)], as anode materials for energy storage system. Such systems showed a remarkable cycle stability without significant loss of power density, in comparison with similar characteristics of the known organic radical batteries, the dual carbon cell, and the electrochemical capacitor. Particularly important is that these novel electrochemical energy storage systems employing stable heavy group 14 element radicals are lithium-free. The electrochemical properties and structures of the reduced and oxidized species were studied by the cyclic voltammetry (CV), electron paramagnetic resonance (EPR) spectroscopy, and X-ray diffraction (XRD).

Grand Prix de la Fondation de la Maison de la Chimie: J.‐P. Sauvage / WACKER Silicone Award: A. Sekiguchi / Friedmund Neumann Prize: M. Köhn / Ignaz L. Lieben Award: J. Roithová

“…Sekiguchi’s research is centered on low‐coordinate organosilicon compounds, including doubly and triply bonded organosilicon species, and silicon‐centered radicals, cations, anions, and radical ions. He has reported in Angewandte Chemie on anode materials based on persilyl‐substituted free radicals,2a and in Chemistry—A European Journal on isolable aryl‐substituted silyl radicals 2b …”

Synthesis of Poly(TEMPO‐Substituted Glycidyl Ether) by Utilizing t‐BuOK/18‐Crown‐6 for an Organic Cathode‐Active Material

“…We have synthesized a series of redox polymers containing nitroxide radical moieties and utilized them as electrode‐active materials in organic radical polymer batteries . Organic batteries are characterized by excellent rate performances and capabilities of fabricating purely organic, flexible, and environmentally benign energy‐storage devices . Radical polymers swell in electrolyte solutions to allow counterions to diffuse smoothly through the polymer layers.…”

Isolable Aryl‐Substituted Silyl Radicals: Synthesis, Characterization, and Reactivity

“…Since then, several other isolable silyl radicals have been reported, including a silyl radical lacking stabilization by π‐conjugation,10a disilene anion11 and cation radicals,12 a disilyne anion radical,13 silylene anion14 and cation radicals,15 alkali‐metal‐substituted silyl radicals,16 and a triplet bis(silyl) radical 17. Moreover, we recently reported that the stable persilyl‐susbtituted Si, Ge, and Sn radicals can work as an electrochemical energy storage system 18. However, isolable and persistent silyl radicals containing other substituents, such as alkyl, aryl, and heteroatom substituents, are less known 6g.…”