Poly(PROXYL-Methacrylate) Polymer for High Redox Potential Organic Electrodes

Radical polymers are actively being investigated in different applications such as batteries. In order to store higher energy, radical polymers with high redox potential are searched. This work describes the synthesis of 2,2,5,5-tetramethylpyrrolin-N-oxyl methacrylate monomer (PROXYL-methacrylate) and its polymerization to get a PolyPROXYL-methacrylate (PPMA) by free radical polymerization. The structures of the monomer and the percentage of redox active groups of the polymer were determined by mean of NMR and UV-Vis spectroscopy, respectively. Cyclic voltammetry of the novel redox polymer revealed a half-wave potential (E1/2) of 3.7 V vs Li+/Li stable at different scan rates, which was ascribed to the efficient swelling and insoluble properties of PPMA. The polyPROXYL-methacrylate polymer exhibits higher nominal redox potential than the reference radical polymer polyTEMPO-methacrylate (PTMA). Li-metal lab-scale cells fabricated with the PPMA cathode active material performed at different C-rates (up to 50 C) with reversible charge/discharge and a specific capacity output of 80 mAh g-1 at 1 C, along with 96 % capacity retention after more than 100 cycles. Finally, the comparison between PPMA and PTMA redox polymers evidenced the superior performances of the PROXYL with respect to TEMPO in terms of energy density and half-wave potential. The synthesis of a novel PROXYL-methacrylate monomer is developed to produce redox polymer with high redox potential (3.7 V vs Li+/Li) that was successful used as electron active material for cathodes in Li-metal batteries. The highly reversible electron transfer process and the optimal chemical stability of the redox polymer allows to get excellent cycling performance at different current rates (up to 5 degrees C) and improved energy density. image