Single- and double-redox reaction of poly(2,2,6,6-tetramethylpiperidinyloxy-4-vinylmethacrylate)/ordered mesoporous carbon composite nitroxide radical polymer battery

Abstract

Rechargeable organic batteries constitute a promising alternative to lithium ion batteries because of the abundance of the necessary raw materials, their lightness, environmental friendliness, high flexibility, and high capacity. However, organic batteries present problems of low conductivity and the instability of their liquid electrolytes. PTMA-impregnated CMK-3 (PTMA/CMK-3) is successfully used as a novel electrode to solve the problems associated with organic batteries. The PTMA/CMK-3 has a theoretical capacity of 111 mAh g−1 with a single-step, single-redox reaction between the nitroxide radical and oxoammonium cation (3.0–4.0 V cut-off) and a theoretical capacity of 222 mAh g−1 with a two-step double-redox reaction between the aminoxy anion and oxoammonium cation (1.5–4.0 V cut-off). Although the PTMA/CMK-3 cells deliver an initial discharge capacity of 110.9 mAh g−1 with the single-redox reaction and 219.8 mAh g−1 with the double-redox at 1 C-rate (which is almost equal to the theoretical capacity), the capacity retentions at the 1000th cycle are 80.7% and 29.3%, respectively. The high degradation associated with the double-redox reaction is ascribed to the irreversible reaction of the aminoxy anion. The resolution of the irreversibility of the aminoxy anion could lead to the commercialization of nitroxide radical-based organic batteries.