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.