Periodic Reporting for period 4 - MOOiRE (Mix-in Organic-InOrganic Redox Events for High Energy Batteries)
Berichtszeitraum: 2023-03-01 bis 2024-02-29
Organic and organometallic materials emerge as one of the attracting alternative technologies for the forthcoming massive adoption of electrochemical energy storage (EES) systems. Indeed, these would allow to cope with raw material supply shortages, lead to a reduced environmental production and recycling footprint, and potentially result in an enhanced manufacturing scalability, globally improving the sustainability of EES devices. Whereas the gravimetric and volumetric energy metrics of organic or organometallic batteries may not currently compete with their inorganic counterparts, the natural abundance of their constituent elements (e.g. C, H, N, O but also Fe, Mn) and the expected mitigation of the battery life-cycle’s environmental burden constitute arguments of choice to counterbalance and eventually overthrow this already receding disadvantage.
One of the primary assets of the current Li-ion battery technology (largely based on Li and Cobalt) is the availability of positive electrode chemistries that are stable to ambient air in the lithium containing reduced form. Whereas there are many opportunities for the transition metal-based chemistries to fulfill these criteria, the organic-based compounds with alike properties remain finger-counted so far. The overall objectives are to explore and develop novel organic and organometallic chemistries bases on organic redox systems coupled with sustainable transition metals (such as Manganese, Iron). The challenge here is to render these systems comparable and competitive in terms of energy storage to the current Cobalt-based batteries. A major challenge thus remains the development of organic battery cathode materials that would contain Li-ion in the reduced form, and be stable in ambient air conditions. This would also results in a high working voltage.
The overall objectives are thus to develop organic chemistries that operate at a high voltage, and release the Li-ions at the first charge utilization. Furthermore, if such systems could be extended to other, more sustainable cation storage, the issues related to limited Li sources can be solved, another objective set in this work.
One of the primary assets of the current Li-ion battery technology (largely based on Li and Cobalt) is the availability of positive electrode chemistries that are stable to ambient air in the lithium containing reduced form. Whereas there are many opportunities for the transition metal-based chemistries to fulfill these criteria, the organic-based compounds with alike properties remain finger-counted so far. The overall objectives are to explore and develop novel organic and organometallic chemistries bases on organic redox systems coupled with sustainable transition metals (such as Manganese, Iron). The challenge here is to render these systems comparable and competitive in terms of energy storage to the current Cobalt-based batteries. A major challenge thus remains the development of organic battery cathode materials that would contain Li-ion in the reduced form, and be stable in ambient air conditions. This would also results in a high working voltage.
The overall objectives are thus to develop organic chemistries that operate at a high voltage, and release the Li-ions at the first charge utilization. Furthermore, if such systems could be extended to other, more sustainable cation storage, the issues related to limited Li sources can be solved, another objective set in this work.
Major achievements and breakthroughs in the organic battery field, and solid-state chemistry of MOFs have been attained. Two organic chemistries, sulfonamides and oximates, have been reported for the first time for battery application, with, in particular, for the conjugated sulfonamide class, extensive work and original design rationale proposed by us. The properties of sulfonamide materials came out beyond the expectations. Further major advance include the development of the 4 V-class organic battery materials, which this time came out as a result of extensive analysis and expertise on the sulfonamide chemistry. Through comprehensive structural analysis and extensive electrochemical studies, we elucidated the relationship between the molecular structure and the ability to fine-tune the redox potential. These findings offered promising opportunities to customize the redox properties of organic electrodes, bridging the gap with their inorganic counterparts for application in sustainable and eco-friendly electrochemical energy storage devices.
The solid-state ionic conduction in Li-ion rich MOF is another major advance, and was the result of analysis of many materials developed in this project. In fact, each phase and material developed in this proposal (more than 50) were systematically tested for ionic and electronic conductivity. And although all were displaying good performances in liquid electrolyte cells (thus cations solvated) none showed solid-state cation conduction and this aspect puzzled us throughout this project – what would it take structurally and compositionally to enable solid-state cation conduction in a MOF or a coordination polymer. So following many hypotheses and attempts, we finally proposed the cation-rich design, wherein the cation will be also sterically frustrated, thus weakly binding to the lattice, and consequently being highly mobile. In making such a MOF, we were able to confirm this, although the conductivity remains in the low limit with thus current work on exploring the higher conductivities, towards the super-ionic range.
Overall, through this project, we have advanced the organic battery field to a next level, by developing novel materials, testing and confirming a series of hypothesis, and providing indications for further developments.
The solid-state ionic conduction in Li-ion rich MOF is another major advance, and was the result of analysis of many materials developed in this project. In fact, each phase and material developed in this proposal (more than 50) were systematically tested for ionic and electronic conductivity. And although all were displaying good performances in liquid electrolyte cells (thus cations solvated) none showed solid-state cation conduction and this aspect puzzled us throughout this project – what would it take structurally and compositionally to enable solid-state cation conduction in a MOF or a coordination polymer. So following many hypotheses and attempts, we finally proposed the cation-rich design, wherein the cation will be also sterically frustrated, thus weakly binding to the lattice, and consequently being highly mobile. In making such a MOF, we were able to confirm this, although the conductivity remains in the low limit with thus current work on exploring the higher conductivities, towards the super-ionic range.
Overall, through this project, we have advanced the organic battery field to a next level, by developing novel materials, testing and confirming a series of hypothesis, and providing indications for further developments.
Overall, the entire work performed and results attained in this project were performed at the edge of state of the art and many advances attained have redefined the work in the organic battery field. With regards to the starting hypothesis of metal binding to the redox center of 1,4-dioxido-2,5-benzenedicarboxylate, we have confirmed this experimentally and shown that redox activity is enabled when metal bind only to carboxylate. An additional outcome of this direction was the observation and analysis of the polarization inductive effect of metal cation on the increase of the redox potential of the ligand, leading to the practical benefit of high voltage materials (publication in JACS - doi: 10.1021/jacs.1c04591 ). Along this work, we have also confirmed another initially proposed hypothesis concerning this organic linker – intrinsic limitation to one-electron redox. The origins are still not clearly identified, but our current view is that the second electron is extracted at a potential higher than the anodic stability of the ligand, leading thus to its irreversible decomposition (experimentally confirmed fact). Following this discovery, we have explored other quinone/dioxido chemistries and have developed two new exotic systems. The first one, based on diacetate functionalized groups came out at a redox of two electrons, with an impressive average redox voltage of 3.4V the origin of this being rooted in the in a stereoelectronic chameleonic effect with an intramolecular conformation change and charge modulation leading to a redox potential increase of 650mV in the solid state as compared to the same chemistry tested in solution (ChemMater - doi: 10.1021/acs.chemmater.0c02989 ). This chemistry however being unique, and has motivated us to look for other.
The main achievement of this project however remains the development of two novel chemistries with intrinsic high-voltage, Li-ion (later extended to other cations) reservoir content, and stable to ambient air. This development took the most efforts allocated in this proposal, with nearly 60% of man-power and budgets allocated to these developments. The two chemistries and the pioneering publications associated are the conjugated oximates (published in Science Advances - doi: 10.1126/sciadv.adg6079 ) and the flagship one, that has sparkle probably most interest in the community, the conjugated sulfonamides (initial publication in Nature Materials - doi: 10.1038/s41563-020-00869-1 ).
The main achievement of this project however remains the development of two novel chemistries with intrinsic high-voltage, Li-ion (later extended to other cations) reservoir content, and stable to ambient air. This development took the most efforts allocated in this proposal, with nearly 60% of man-power and budgets allocated to these developments. The two chemistries and the pioneering publications associated are the conjugated oximates (published in Science Advances - doi: 10.1126/sciadv.adg6079 ) and the flagship one, that has sparkle probably most interest in the community, the conjugated sulfonamides (initial publication in Nature Materials - doi: 10.1038/s41563-020-00869-1 ).