An all‐organic battery consisting of two redox‐polymers, namely poly(2‐vinylthianthrene) and poly(2‐methacrylamide‐TCAQ) is assembled. This all‐organic battery shows excellent performance characteristics, namely flat discharge plateaus, an output voltage exceeding 1.3 V, and theoretical capacities of both electrodes higher than 100 mA h g−1. Both organic electrode materials are synthesized in two respective three synthetic steps using the free‐radical polymerization technique. Li‐organic batteries manufactured from these polymers prove their suitability as organic electrode materials. The cathode material poly(2‐vinylthianthrene) (3) displays a discharging plateau at 3.95 V versus Li+/Li and a discharge capacity of 105 mA h g−1, corresponding to a specific energy of about 415 mW h g−1. The anode material poly(2‐methacrylamide‐TCAQ) (7) exhibits an initial discharge capacity of 130 mA h g−1, corresponding to 94% material activity. The combination of both materials results in an all‐organic battery with a discharge voltage of 1.35 V and an initial discharge capacity of 105 mA h g−1 (95% material activity).

SEC measurements. Last but not the least, the authors thank Nicole Fritz for mass spectrometric measurements and Sandra Köhn and Beate Lentvogt for elemental analysis. Open access funding enabled and organized by Projekt DEAL.

Herein, we present a novel copolymer (1), which incorporates (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) as a redox-active compound and the zwitterionic [(2-(methacryloxy)ethyl)dimethyl-(3-sulfopropyl)]ammonium hydroxide as a solubilizing comonomer, for the application as catholyte species within aqueous redox flow batteries (RFBs). The presented polymer-based redox-active material exhibits a high degree of oxidation and, compared to other commonly utilized active polymeric materials, a high solubility exceeding 20 Ah L −1 , while still featuring a low viscosity in 1.5 M NaCl aq solution. The electrochemical behavior was investigated by cyclic voltammetry, and a reversible redox reaction at E 0 = 0.7 V versus the Ag/AgCl reference electrode of the TEMPO/TEMPO + redox pair was observed. Symmetric design battery studies with two different types of membranes, a size-exclusion versus an anion-exchange membrane, were used to evaluate the applicability of this polymer in the RFB setup. Long-term stability tests over 1000 cycles indicate good stability with a capacity loss of ca. 0.08% per cycle utilizing a size-exclusion and an anion-exchange membrane, respectively. Finally, an allorganic aqueous RFB was operated utilizing 1 as the catholyte species and N,N′-dimethyl-4,4′-bipyridinium dichloride (MV) as the anolyte species. Such RFB exhibits Coulombic efficiencies of 99.01 ± 1.40% over 125 consecutive cycles, an energy efficiency of ca. 93%, and an initial energy density of 5.33 Wh L −1 during the studied discharge process.

Organic polymer-based batteries represent a promising alternative to present-day metal-based systems and a valuable step toward printable and customizable energy storage devices. However, most scientific work is focussed on the development of new redox-active organic materials, while straightforward manufacturing and sustainable materials and production will be a necessary key for the transformation to mass market applications. Here, a new synthetic approach for 2,2,6,6tetramethyl-4-piperinidyl-N-oxyl (TEMPO)-based polymer particles by emulsion polymerization and their electrochemical investigation are reported. The developed emulsion polymerization protocol based on an aqueous reaction medium allowed the sustainable synthesis of a redox-active electrode material, combined with simple variation of the polymer particle size, which enabled the preparation of nanoparticles from 35 to 138 nm. Their application in cell experiments revealed a significant effect of the size of the active-polymer particles on the performance of poly(2,2,6,6-tetramethyl-4-piperinidyl-N-oxyl methacrylate) (PTMA)-based electrodes. In particular rate capabilities were found to be reduced with larger diameters. Nevertheless, all cells based on the different particles revealed the ability to recover from temporary capacity loss due to application of very high charge/discharge rates.

The reversible addition-fragmentation chain-transfer (RAFT) process represents a sophisticated polymerization technique for the preparation of tailored and well-defined polymers from acrylates, acrylamides, and (meth)acrylates. The direct switching from other methods, such as cationic polymerizations, without the need for tedious functionalization and purification steps remains challenging. Within this study, it is demonstrated that poly(2-oxazoline) (P(Ox)) macro chain-transfer agents (macro-CTAs) can be prepared through the quenching of the cationic ring-opening polymerization with a carbonotrithioate salt. The end-functionalization of the P(Ox)s is observed to be almost quantitative and the macro-CTAs could be directly used for RAFT polymerization without further purification. This one-pot procedure could be extended to a variety of (multi)block copolymers consisting of different 2-oxazolines and acrylates with good-to-excellent control. Kinetic studies revealed the controlled polymerization of block copolymers, which are further accessible for α- and ω-end-functionalization. The simplicity and versatility of the approach promise a straightforward access to block copolymers from cationic and controlled radical polymerizations.