The benzotriazinyl radical is a highly stable organic radical that is known to possess fast and reversible oxidation and reduction electrochemical processes. Such properties make it an ideal candidate for use as an anodic or cathodic charge storage material in a new class of high-power secondary batteries known as organic radical batteries. Towards this application, several new benzotriazinyl radical derivatives were synthesized and fully characterized using electronic absorption, EPR, and IR spectroscopy as well as elemental analysis and mass spectrometry. The electrochemical properties of the radicals were studied using cyclic voltammetry. The introduction of electron donating groups onto the structure of the radical was found to result in cathodic shifts in both of the electrochemical processes, without loss of reversibility. It was also found that in some cases functional groups led to the destabilization of the radical to a known chemical oxidation pathway that resulted in the formation of closed-shell iminoquinone compounds. These materials demonstrated good multi-electron accepting properties, undergoing two reversible one-electron reduction processes. Synthetic methodologies were developed for the preparation of two new classes of benzotriazinyl biradicals. One class used an expansion of a known benzotriazinyl radical synthesis to prepare a m-phenylene-bridged biradical, while the other class used microwave-assisted synthesis to prepare biradicals bridged by electron accepting aromatic diimides. Spectroscopic studies of both classes of biradical showed electronic isolation of the two radicals within each molecule, consistent with computational predictions. This resulted in minimal perturbation of the electrochemistry of these compounds from that of typical benzotriazinyl radicals. The solid state properties of a selection of benzotriazinyl radical derivatives were studied. Structural information obtained through single crystal X-ray diffraction studies showed significant intermolecular π-π and hydrogen bonding interactions. These solid state interactions were found to provide pathways for magnetic exchange, as determined using SQUID magnetometry. Additionally, preliminary conductivity studies indicated semiconducting behaviour in the compounds that were studied, warranting further studies. Anionic polymerization of a vinyl-functionalized benzotriazinyl radical was investigated as a method for the synthesis of a pendant benzotriazinyl polyradical with a saturated backbone. The electrochemistry of the putative polymer was identical to the monomer, maintaining reversibility of both the oxidation and reduction processes and verifying that the polymer could be used as an anodic or cathodic charge storage material. SQUID magnetometry was used to estimate a polymer spin content to be ~ 44 %. / Graduate / 0485

A non-crosslinking approach that covalently bonds nitroxide polymer brushes onto the ITO substrates via surface-initiated atom transfer radical polymerization (ATRP) was develpoed. Since the indium tin oxide (ITO)-silane covalent bonding providesvery strong chemical bonds to adsorb the nitroxide polymer brushes on ITO, it prevents polymers from dissolving into electrolyte solvent and thus improves its electrochemical properties. Moreover, micro-contact printing technology was used to pattern nitroxide polymer brushes on an ITO surface for the potential application in microbatteries. The morphology of electrodes was observed by atomic force microscopy.The electrochemical properties of the cathode were also studies.

Nitroxide polymer brushes grafted on silica nanoparticles as binder-free cathode for organic radical battery have been investigated. Scanning electron microscopy, transmission electron microscopy, infrared spectroscopy and electron spin resonance confirm that the nitroxide polymer brushes are successfully grafted onto silica nanoparticles via surface-initiated atom transfer radical polymerization. The thermogravimetric analysis results indicate that the onset decomposition temperature of these nitroxide polymer brushes is found to be ca. 201 ◦C. The grafting density of the nitroxide polymer brushes grafted on silica nanoparticles is 0.74¡V1.01 chains nm−2. The results of the electrochemical quartz crystal microbalance indicate that the non-crosslinking nitroxide polymer brushes prevent the polymer from dissolving into organic electrolytes. Furthermore, the electrochemical results show that the discharge capacity of the polymer brushes is 84.9¡V111.1 mAh g−1 at 10 C and the cells with the nitroxide polymer brush electrodes have a very good cycle-life performance of 96.3% retention after 300 cycles.

The electrochemical behavior of a poly(2,2,6,6-tetramethylpiperidin- 1-oxyl-4-yl methacrylate) (PTMA) cathode in organic radical batteries with lithium bis(trifluoromethylsulfonyl)imide in N-butyl-N-methyl- pyrrolidinium bis(trifluoromethylsulfonyl)imide (LiTFSI/BMPTFSI) ionic liquid electrolytes is investigated. The ionic liquid electrolytes containing a high concentration of the LiTFSI salt have a high polarity, preventing the dissolution of the polyvinylidene fluoride (PVdF) binder and PTMA in the electrolytes. The results of cyclic voltammetry and AC impedance indicate that an increase in the LiTFSI concentration results in a decrease in the impedance of the lithium electrode, which affects the C-rate performance of batteries. The discharge capacity of the PTMA composite electrode in a 0.6 m LiTFSI/BMPTFSI electrolyte is 92.9 mAh g−1 at 1 C; its C-rate performance exhibits a capacity retention, 100 C/1 C, of 88.3%. Moreover, the battery with the 0.6-m LiTFSI/BMPTFSI electrolyte has very good cycle-life performance.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20927号 / 理博第4379号 / 新制||理||1629(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 大須賀 篤弘, 教授 丸岡 啓二, 教授 依光 英樹 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

We reported a non-crosslinking approach to synthesize nitroxide radical polymer brushes for thin-film electrodes via surface-initiated atom transfer radical polymeization (SI-ATRP), which was effective to yield the organic radical polymer brushes with high grafting density and to attain a uniform surface. As mentioned above, the covalent bonding of nitroxide polymer brushes to the conducting substrate not only prevented the polymer dissolution into organic electrolyte solution but improved the cycle life performance of batteries. Moreover, they can be the potential application in microbatteries by using microcontact printing to produce the patterned nitroxide polymer brushes on a conducting substrate. Even though the organic radical polymer brushes provided a new approach to syn-thesize thin-film electrodes, they still existed many problems that needed to study and to figure out. We discussed the morphology and electrochemical performance about ni-troxide radical polymer in the thesis. In the measurement of surface properties, we used the contact angle, electron spectroscopy for chemical analysis (ESCA) and atomic force microscopic (AFM) to proceed. Another, in the measurement of electrochemical analysis, we used the cyclic voltammetry(CV), alternating current (AC) impedance and charge-discharge to understand the regarding mechanism in this polymer layer during the electrochemical reaction. In chapter 4, we discussed the oxidative problem in the polymer brushes. It should be well controlled during the oxidation reaction, because the oxidation level may affect the diffusion of electron that resulted the capacity better or not. In chapter5, we controlled the density of polymer brushes to construct the possible mechanism during the electro-chemical reaction, and found out the possible factors that affected the electrochemistry. In chapter 6, we applied the better results from the front chapter to the organic radical battery, and compared their electrical performance.