Thanks to the use of abundant chemical elements, organic chemistry provides great opportunities for discovering innovative electrode materials, which could be prepared (i) from renewable resources (biomass) and (ii) via eco-efficient processes, making the concept of greener and sustainable batteries possible [1]. Two types of reaction mechanisms can be used: n-type involving charge transfer with cation release/uptake and p-type involving anion uptake/release [2-5]. We are putting a lot of efforts on greener and sustainable organic batteries. In this communication, we report on novel materials, their uncommon reaction mechanism, and the performance of full aqueous cells. We focus on aqueous organic batteries as a new promising green technology, barely studied yet, for which negative electrodes are missing. We have designed and synthesized novel mixed p- and n-type “bi-block” oligomer negative electrodes with repeating units made of naphthalene diimide and bipyridinium units [6]. They demonstrate optimal potential, extremely fast kinetics and highly competitive capacity and cyclability in both neutral aqueous Na and Mg electrolytes, including ocean water. Based on these findings, full organic cells bearing millimeter thick electrodes were assembled and tested [7]. These findings make a big step forward the design of low-cost rocking-chair dual-ion aqueous batteries. References 1) P. Poizot, F. Dolhem, Energy Environ. Sci. 4, 2003 (2011). 2) Z. Song and H. Zhou, Energy Environ. Sci. 6, 2280 (2013). 3) S. Gottis, A.-L. Barrès, F. Dolhem, P. Poizot, ACS Appl Mater Interfaces 6, 10870 (2014). 4) E. Deunf, P. Moreau, E. Quarez, D. Guyomard, F. Dolhem, P. Poizot, J. Mater. Chem. A, 4, 6131 (2016). 5) E. Deunf, P. Jimenez, D. Guyomard, F. Dolhem, P. Poizot, Electrochem. Comm., 72, 64 (2016). 6) S. Perticarari, Y. Sayed-Ahmad-Baraza, C. Ewels, P. Moreau, D. Guyomard, P. Poizot, F. Odobel, J. Gaubicher, Adv. Energy Mater., 8, 1701988 (2018). 7) S. Perticarari, E. Grange, T. Doizy, Y. Pellegrin, E. Quarez, K. Oyaizu, A. J. Fernandez, D. Guyomard, P. Poizot, F. Odobel and J. Gaubicher, Chem. Mat., in revision

Thick electrodes with sodium and even anion intercalation organic compounds integrated in a neutral-pH aqueous battery offer unique advantages in terms of round trip efficiency, environmental impact, and scalability for off- or on-grid renewable energy storage. Herein, we report the first anion-rocking chair/dual-ion organic battery. The latter reaches 35 Wh/kg(materials) at a C/8 rate. It shows remarkable cyclability and coulombic efficiency in a cheap and neutral NaClO4 electrolyte pouch cell with highly loaded millimeter-thick electrodes (5 mAh/cm(2)). This achievement is based on a thorough study of a commercial 2,2,6,6-tetramethylpiperidin-yl-N-oxyl (TEMPO) (TEMPO) benzene derivative, namely, 4-hydroxy TEMPO benzoate, and its naphthalene analog (4-carboxy TEMPO naphthalate) as positive electrode materials and a bipyridinium-naphthalene oligomer as the negative electrode. Combined UV-vis spectroelectrochemistry and operando X-ray diffraction account for the much improved cyclability of the hydrophobic 4-carboxy TEMPO naphthalate at the expense of a lower specific capacity. This trend is reversed in the case of the 4-hydroxy TEMPO benzoate derivative. Results show that the kinetic limitations of 4-hydroxy TEMPO benzoate are associated with the surrounding composite electrode, whereas inner-grain ionic and/or electronic transports play a decisive role for 4-carboxy TEMPO naphthalate.

Aqueous batteries, particularly those integrating organic active materials functioning in a neutral pH environment, stand out as highly promising contenders in the stationary electrochemical storage domain, owing to their unparalleled safety, sustainability and low-cost materials. Herein, a novel di-block oligomer (DNVBr), serving as the negative electrode of an all-organic aqueous battery, is shown to offer exceptional output capabilities. The battery's performance is further enhanced by a unique intermixed p/n-type storage mechanism, which is able to simultaneously exchange light and naturally abundant Na+, Mg2+ and Cl-. Reaching up to 105 mAh/g, this system shows remarkable capacity retention for several thousand cycles (6500 cycles, ~40 days) in various neutral electrolytes, including raw ocean water (~3000 cycles, ~75 days). The surprisingly fast kinetics of this di-block oligomer allow to attain an unmatched specific capacity of near to 60mAh/g electrode while entirely devoid of conducting additives, and more than 80mAh/g electrode with 10% carbon additive, as well as displaying an areal capacity as high as 3.4mAh/cm2 at C rate. Full cell validation was demonstrated over 1600 cycles by virtue of a commercial TEMPO molecule, which permitted an energy density of close to 40Wh/kgmaterials at C rate in a self-pH-buffered and inexpensive aqueous electrolyte.

Aqueous ionic batteries are a promising technology for environmentally friendly grid storage systems as they reduce cost, risk and environmental impact, although this is at the expense of energy density.[1] Designing such batteries from inexpensive, abundant, recyclable and non-toxic organic active materials provides a way towards improving both the environmental and economic impact of these systems. Herein, the first battery materials that work with simultaneous uptake and release of both cations (Na, Mg) and anions are proposed by designing mixed p-type and n-type “di-block” oligomers[2,3]. It demonstrates optimal potential, extremely fast kinetics and highly competitive capacity and cyclability in both neutral Na and Mg electrolytes, including ocean water. Through a combination of UV-Vis spectroelectrochemistry, EQCM, and operando synchrotron-XRD a simultaneous cation/anion insertion mechanism was proven and rationalized. The surprisingly fast kinetics of this di-block oligomer allow to attain an unmatched specific capacity of near to 60mAh/g per gram of electrode while entirely devoid of conducting additives, and more than 80mAh/g per gram of electrode with 10% carbon additive. Based on these findings, full organic cells with millimeter-thick electrodes were assessed [4]. These findings may well provide a viable option, thereby promoting the design of cutting-edge, low-cost, rocking-chair dual-ion aqueous batteries. [1] Wu Li, J. R. Dahn, D. S. Wainwright, Science. 1994, 264, 1115-1118 [2] S. Perticarari, Y. Sayed-Ahmad-Baraza, C. Ewels, P. Moreau, D. Guyomard, P. Poizot, F. Odobel and J. Gaubicher, Adv. Energy Materials, 2018, 8 (8), 1701988 [3] S. Perticarari, T. Doizy, P. Soudan, C. Ewels, C. Latouche, D. Guyomard,F. Odobel, P. Poizot, J. Gaubicher, Adv. Energy Materials, 2019, in press [4] S. Perticarari, E. Grange, T. Doizy, Y. Pellegrin, A.-J Fernandez-Ropero, D. Guyomard, P. Poizot, F. Odobel and J. Gaubicher, Chem . Mater. 2019, (10.1021/acs.chemmater.8b03282

Aqueous batteries are an emerging candidate for low‐cost and environmentally friendly grid storage systems. Designing such batteries from inexpensive, abundant, recyclable, and nontoxic organic active materials provides a logical step toward improving both the environmental and economic impact of these systems. Herein the first ever battery material that works with simultaneous uptake and release of both cations and anions is proposed by coupling p‐type (bipyridinium) and n‐type (naphthalene diimide) redox moieties. It represents one of a new family of electrode materials which demonstrates an optimal oxidation potential (−0.47 V vs saturated calomel electrode), extremely fast kinetics, a highly competitive capacity (63 mA h g−1 at 4C), and cyclability in both neutral Na+ and Mg2+ electrolytes of molar range concentration. Through a combination of UV–vis spectroelectrochemistry, electrochemical quartz‐crystal microbalance, Operando synchrotron‐X‐ray diffraction, and density functional theory calculations a novel dual cation/anion insertion mechanism was proven and rationalized. Based on these findings, this innovative p/n‐type product may well provide a viable option for use as a negative electrode material, thereby promoting the design of cutting‐edge, low‐cost, rocking‐chair dual‐ion aqueous batteries.

In article number 1701988, Joël Gaubicher, Philippe Poizot, Fabrice Odobel and co-workers report the first ever battery material that works with simultaneous uptake and release of both cations and anions. This represents one of a new family of organic electrode materials that shows great promise, thereby promoting the design of cutting-edge, low-cost, rocking-chair dual-ion aqueous batteries.

Matériaux d'électrode organiques pour batterie aqueuse à bas coût pour le stockage des énergies renouvelables La gestion des sources renouvelables est probablement l'un des enjeux majeurs du 21ème siècle. La part croissante de ces ressources intermittentes et fluctuantes telles que les énergies solaires, éoliennes et marines connectées au réseau électrique requiert des systèmes de stockage efficaces pour sécuriser et réguler l'approvisionnement électrique. L'objectif principal de cette thèse est donc la création de batteries aqueuses écologiques et durables à base de matériaux organiques à faible coût. En particulier, ce projet avait pour but d’identifier des stratégies pour synthétiser, comprendre et modifier des matériaux redox idoines pour en optimiser les réactions électrochimiques et chimiques. De plus, cette technologie a nécessité une mise en oeuvre particulière de ces matériaux mettant en jeu des électrodes millimétriques jamais réalisées à ce jour. Une nouvelle famille de molécules redox de type p/n a été identifiée. Leur comportement électrochimique, rationalisés par de nombreuses caractérisations physiques, a mis en évidence l’échange simultané de cations et d’anions ce qui n’a jamais été montré dans le domaine des batteries. En outre ce matériau permet une cyclabilité remarquable notamment dans l’eau de mer. La synthèse et le comportement électrochimique de différents dérivés du TEMPO en tant que matériaux actifs d'électrode positive ont également été évalués. Sur la base de ces découvertes des résultats très encourageants ont été obtenus avec les batteries aqueuses organiques complètes composées d'électrodes millimétriques.