Anion‐Rocking Chair Batteries with Tuneable Voltage using Viologen‐ and Phenothiazine Polymer‐based Electrodes**

Abstract

Organic battery electrode materials offer the unique opportunity for full cells to operate in an anionrocking chair mode. For this configuration a pair of p‐type redox‐active electrode materials is required with a substantial potential gap between their redox processes. We herein investigate viologenfunctionalized polystyrenes as negative electrode paired with a phenothiazine polymer as positive electrode in all‐organic full cells. The 10% crosslinked viologen polymer X10‐PVBV gave better performance than the linear PVBV and was employed in a full cell as negative electrode with crosslinked poly(3‐vinyl‐N‐methylphenothiazine) (X‐PVMPT) as positive electrode. Three cell configurations regarding the voltage range were investigated, of which one with an operating potential of 0.9 V gave the highest performance. The full cell delivered a specific discharge capacity of 64 mA h g−1 (of X‐PVMPT) in the first cycle and a capacity retention of 79% after 100 cycles. This is one of only few reported anion rocking chair all‐organic cells and the first employing a phenothiazine‐based positive electrode material.

All‐Organic Battery Based on Deep Eutectic Solvent and Redox‐Active Polymers**

“…Details on the electrode composition and fabrication can be found in the experimental section. More fundamental information on the used polymers and electrodes can be found elsewhere [20,44,45] …”

“…A brief description of the synthesis of X‐PVBV 2+ is provided in the supporting information. Further information will be published elsewhere [45] . The resulting slurries were coated on Al‐foil which was etched with 5 wt % KOH solution prior to use.…”

Unlocking twofold oxidation in phenothiazine polymers for application in symmetric all-organic anionic batteries

“…It features a stable and reversible oxidation, a high voltage vs. Li/Li + and high specific capacity (3.5 V vs. Li/Li + and 125.7 mAh g −1 per electron, for N-methyl phenothiazine), which is accompanied by the synthetic possibility to incorporate PT into different motifs. 4,5,24,[32][33][34][35][36][37] Furthermore, PT is generally capable of two singleelectron oxidations from its neutral form to a radical cation and further to a dication (Figure 1). The two processes are observed at high potentials of 3.5 V 38,39 and 4.2 V vs. Li/Li + (approximation based on the redox potential of the second oxidation of N-ethylphenothiazine (0.93 V vs. Fc/Fc + ) 37 and the potential of Fc/Fc + (3.25 vs. Li/Li + ) 40 ), making PT an attractive candidate for positive electrode materials.…”

Unlocking twofold oxidation in phenothiazine polymers for application in symmetric all-organic anionic batteries

“…Lastly, combining two p-type materials produces an anion-rocking chair cell, also called anionic battery, the counterpart to the cation-rocking chair cell. [24][25][26][27][28][29][30][31] In this configuration, the anions diffuse between the electrodes between charged and discharged states. All-organic anion-rocking chair cells offer unique advantages such as the possibility to construct them completely metal-free cells, significantly decreasing their toxicity while further raising their sustainability.…”

“…It features a stable and reversible oxidation, a high voltage vs. Li/Li + and high specific capacity (3.5 V vs. Li/Li + and 125.7 mAh g −1 per electron, for N-methyl phenothiazine), which is accompanied by the synthetic possibility to incorporate PT into different motifs. 4,5,24,[32][33][34][35][36][37] Furthermore, PT is generally capable of two singleelectron oxidations from its neutral form to a radical cation and further to a dication (Figure 1). The two processes are observed at high potentials of 3.5 V 38,39 and 4.2 V vs. Li/Li + (approximation based on the redox potential of the second oxidation of N-ethylphenothiazine (0.93 V vs. Fc/Fc + ) 37 and the potential of Fc/Fc + (3.25 vs. Li/Li + ) 40 ), making PT an attractive candidate for positive electrode materials.…”