10 research outputs found
From the design of innovative organic electrode materials to their integration in all organic batteries
RĂ©pondre aux besoins croissants en termes de stockage Ă©lectrochimique sans Ă©puiser les ressources naturelles exige de promouvoir des technologies de batteries en rupture Ă la fois efficientes mais aussi Ă faible impact au plan environnemental. La conception de batteries organiques pourrait s'avĂ©rer ĂȘtre une partie de la solution. En effet, la richesse de la chimie organique offre une multitude de possibilitĂ©s pour dĂ©velopper des matĂ©riaux d'Ă©lectrode innovants Ă partir dâĂ©lĂ©ments abondants et peu coĂ»teux. PrĂšs de 40 ans aprĂšs la dĂ©couverte des polymĂšres conducteurs, des batteries Li-organiques offrent maintenant dâintĂ©ressantes performances en cyclage. Pourtant, la synthĂšse de matĂ©riaux organiques lithiĂ©s Ă©lectroactifs Ă haut-potentiel ainsi que celle de matĂ©riaux organiques de type p Ă©lectroactifs Ă bas potentiel se sont avĂ©rĂ©es assez complexes et par consĂ©quent, trĂšs peu d'exemples de cellules « tout organique » existent. Au cours de ce travail de recherche, nous avons mis en lumiĂšre une approche chimique originale consistant Ă perturber la structure Ă©lectronique de lâentitĂ© organique Ă©lectroactive (modulation des effets inductifs) au moyen dâun cation spectateur faiblement Ă©lectropositif ce qui conduit Ă une augmentation significative du potentiel redox des matĂ©riaux d'Ă©lectrodes organiques lithiĂ©s dĂ©jĂ connus. Cette dĂ©couverte nous a permis de dĂ©velopper une batterie Li-ion « tout organique » capable dâoffrir une tension de sortie dâau moins 2,5 V sur plus de 300 cycles. Ensuite, nous avons cherchĂ© Ă concevoir des matĂ©riaux de type p capables de fonctionner Ă bas potentiel et ainsi Ă©laborĂ© des batteries Anion-ion « tout organique ». Enfin, une Ă©tude prĂ©liminaire dâune nouvelle famille de composĂ©s potentiellement bipolaires au plan redox (intĂ©gration de centres redox de type n et de type p) a Ă©galement Ă©tĂ© rĂ©alisĂ©e.Meeting the ever-growing demand for electrical storage devices, without depleting natural resources, requires both superior and âgreenerâ battery technologies. Developing organic batteries could well provide part of the solution since the richness of organic chemistry affords us a multitude of avenues for uncovering innovative electrode materials based on abundant, low-cost chemical elements. Nearly 40 years after the discovery of conductive polymers, long cycling stability in Li-organic batteries has now been achieved. However, the synthesis of high-voltage lithiated organic cathode materials and the synthesis of low-voltage p type organic anode materials is still rather challenging, so very few examples of all-organic cells currently exist. Herein, we first present an innovative approach consisting in the substitution of spectator cations and leading to a significant increase of the redox potential of lithiated organic electrode materials thanks to an inductive effect. These results enable developing an all-organic Li-ion battery able to deliver an output voltage above 2.5 V for more than 300 cycles. We then design two p type organic electrode materials able of being charged at low potentials for developing all-organic Anion-ion batteries able to deliver an output voltage at least 1.5 V. Finally, we present a preliminary study of a new family of potentially bipolar compounds
Tuning the Chemistry of Organonitrogen Compounds for Promoting All-Organic Anionic Rechargeable Batteries
International audienc
Raising the redox potential in carboxyphenolate-based positive organic materials via cation substitution
International audienceMeeting the ever-growing demand for electrical storage devices requires both superior and "greener" battery technologies. Nearly 40 years after the discovery of conductive polymers, long cycling stability in lithium organic batteries has now been achieved. However, the synthesis of high-voltage lithiated organic cathode materials is rather challenging, so very few examples of all-organic lithium-ion cells currently exist. Herein, we present an inventive chemical approach leading to a significant increase of the redox potential of lithiated organic electrode materials. This is achieved by tuning the electronic effects in the redox-active organic skeleton thanks to the permanent presence of a spectator cation in the host structure exhibiting a high ionic potential (or electronegativity). Thus, substituting magnesium (2,5-dilithium-oxy)-terephthalate for lithium (2,5-dilithium-oxy)-terephthalate enables a voltage gain of nearly +800 mV. This compound being also able to act as negative electrode via the carboxylate functional groups, an all-organic symmetric lithium-ion cell exhibiting an output voltage of 2.5 V is demonstrated
A H-bond stabilized quinone electrode material for Liâorganic batteries: the strength of weak bonds
Small organic materials are generally plagued by their high solubility in battery electrolytes. Finding approaches to suppress solubilization while not penalizing gravimetric capacity remains a challenge. Here we propose the concept of a hydrogen bond stabilized organic battery framework as a viable solution. This is illustrated for 2,5-diamino-1,4-benzoquinone (DABQ), an electrically neutral and low mass organic chemical, yet with unusual thermal stability and low solubility in battery electrolytes. These properties are shown to arise from hydrogen bond molecular crystal stabilization, confirmed by a suite of techniques including X-ray diffraction and infrared spectroscopy. We also establish a quantitative correlation between the electrolyte solvent polarity, molecular structure of the electrolyte and DABQ solubility â then correlate these to the cycling stability. Notably, DABQ displays a highly reversible (above 99%) sequential 2-electron electrochemical activity in the solid phase, a process rarely observed for similar small molecular battery chemistries. Taken together, these results reveal a potential new strategy towards stable and practical organic battery chemistries through intramolecular hydrogen-bonding crystal stabilization
Tuning the Chemistry of Organonitrogen Compounds for Promoting AllâOrganic Anionic Rechargeable Batteries
A H-bond stabilized quinone electrode material for Liâorganic batteries: the strength of weak bonds
International audienc
Influence of Polymorphism on the Electrochemical Behavior of Dilithium (2,3-Dilithium-oxy)-terephthalate vs. Li
International audienceOrganic electrode materials offer obvious opportunities to promote cost-effective and environmentally friendly rechargeable batteries. Over the last decade, tremendous progress has been made thanks to the use of molecular engineering focused on the tailoring of redox-active organic moieties. However, the electrochemical performance of organic host structures relies also on the crystal packing, like the inorganic counterparts, which calls for further efforts in terms of crystal chemistry to make a robust redox-active organic center electrochemically efficient in the solid state. Following our ongoing research aiming at elaborating lithiated organic cathode materials, we report herein on the impact of polymorphism on the electrochemical behavior of dilithium (2,3-dilithium-oxy-)terephthalate vs. Li. Having isolated dilithium (3-hydroxy-2-lithium-oxy)terephthalate through an incomplete acid-base neutralization reaction, its subsequent thermally induced decarboxylation mechanism led to the formation of a new polymorph of dilithium (2,3-dilithium-oxy-)terephthalate referred to as Li4-o-DHT (ÎČ-phase). This new phase is able to operate at 3.1 V vs. Li+/Li, which corresponds to a positive potential shift of +250 mV compared to the other polymorph formerly reported. Nevertheless, the overall electrochemical process characterized by a sluggish biphasic transition is impeded by a large polarization value limiting the recovered capacity upon cycling
Through-Space Charge Modulation Overriding Substituent Effect: Rise of the Redox Potential at 3.35 V in a Lithium-Phenolate Stereoelectronic Isomer
Raising the operating potential of the organic positive electrode materials is a crucial challenge if they are to compare with lithium-ion inorganic counterparts. Although many efforts have been directed on tuning through substituent electronic effect, the chemistries than can operate above 3 V vs Li+/Li0, and thus be air stable in the Li-reservoir form (alike the conventional inorganic Li-ion positive electrode materials) remain finger-counted. Herein, we report on a new n-type organic Li-ion positive electrode materialâthe tetralithium 2,5-dihydroxy-1,4-benzenediacetateâwith a remarkably high redox potential of 3.35 V vs Li+/Li0 attained notably in the solid phase. The origin of the high-energy content in this quinone derivative is found in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650 mV in the solid state as compared to the same chemistry tested in solution (2.70 V vs Li+/Li0). The conformational dependent electroactivity rationale is supported by electrochemical and crystallography analysis, comparative infrared spectroscopy, and DFT calculation. We identify and make a linear correlation between the enolate vibrational modes and the redox potential, with general applicability for possibly other phenolate redox chemistries. Owing to these effects, this lithiated quinone is stable in ambient air and can be processed and handled alike the conventional inorganic Li-ion positive electrode materials. Whereas intrinsic to high voltage operation stability issues remain to be solved for practical implementation, our fundamental in nature and proof-of-concept study highlights the strong amplitude of through-space charge modulation effects in designing new organic Li-ion positive electrode chemistries with practical operating potential