Alae Eddine Lakraychi

Organic electrode materials (OEMs) offer a sustainable alternative to inorganic cathodes but typically suffer from low intrinsic electronic conductivity. The material historically reported as bis‐tetraaminobenzoquinone (TAQ) exhibits bulk conductivity two orders of magnitude higher than its close analogue tetraaminophenazine‐tetraone (TAPT), despite their common precursor and nearly identical short‐range structure. This disparity has previously been attributed to distinct molecular skeletons, with TAQ proposed to adopt a piperazine‐type linkage and TAPT a pyrazine ring. Here, combining synchrotron x‐ray scattering, solid‐state ¹⁵ N and ¹³ C nuclear magnetic resonance (NMR), microcrystal electron diffraction (MicroED), continuous‐wave and pulsed electron paramagnetic resonance (EPR) spectroscopy, we show that “TAQ” has the same pyrazine‐based molecular structure as TAPT, with no evidence for piperazine core or keto–enol tautomerization. Their key difference lies in synthesis‐dependent degree of crystallinity: “TAQ” exhibits greater long‐range structural coherence and a crystallographically resolved intermolecular hydrogen‐bonding network, whereas TAPT is more disordered. EPR further shows that the higher structural order in “TAQ” is associated with a strongly delocalized π‐spin manifold, while TAPT favors localized or weakly delocalized radicals and stronger local spin coupling. These findings identify degree of crystallinity and hydrogen‐bonding order as key structural features associated with radical delocalization and enhanced conductivity in organic electrodes.

Organic electrode materials (OEMs) offer a sustainable alternative to inorganic cathodes but typically suffer from low intrinsic electronic conductivity. The material historically reported as bis‐tetraaminobenzoquinone (TAQ) exhibits bulk conductivity two orders of magnitude higher than its close analogue tetraaminophenazine‐tetraone (TAPT), despite their common precursor and nearly identical short‐range structure. This disparity has previously been attributed to distinct molecular skeletons, with TAQ proposed to adopt a piperazine‐type linkage and TAPT a pyrazine ring. Here, combining synchrotron x‐ray scattering, solid‐state ¹⁵ N and ¹³ C nuclear magnetic resonance (NMR), microcrystal electron diffraction (MicroED), continuous‐wave and pulsed electron paramagnetic resonance (EPR) spectroscopy, we show that “TAQ” has the same pyrazine‐based molecular structure as TAPT, with no evidence for piperazine core or keto–enol tautomerization. Their key difference lies in synthesis‐dependent degree of crystallinity: “TAQ” exhibits greater long‐range structural coherence and a crystallographically resolved intermolecular hydrogen‐bonding network, whereas TAPT is more disordered. EPR further shows that the higher structural order in “TAQ” is associated with a strongly delocalized π‐spin manifold, while TAPT favors localized or weakly delocalized radicals and stronger local spin coupling. These findings identify degree of crystallinity and hydrogen‐bonding order as key structural features associated with radical delocalization and enhanced conductivity in organic electrodes.

All-solid-state batteries are considered a promising next-generation energy storage technology due to their high safety and energy density. However, a major challenge for practical applications is the need for high external pressure to maintain intimate solid–solid contact and preserve the integrity of active material particles during operation. In this work, we demonstrate that organic active materials, with their inherent softness and high malleability, can enable stable operation under stack pressure. Using bistetraaminobenzoquinone (TAQ) as a model system, we show that solid-state cells with TAQ-based cathodes achieve stable cycling and promising rate performance at just 1 MPa of external pressure, retaining 80.3% capacity after 100 cycles. Operando scanning electron microscope (SEM) reveals that TAQ maintains structural integrity without crack formation, in contrast to inorganic-based single-crystal cathodes, which develop cracks during the first charge. These findings highlight the potential of organic electrode materials to facilitate solid-state battery operation under significantly reduced external pressures.

The growing need for sustainable energy storage solutions has heightened interest in sodium-ion batteries as a viable alternative to traditional lithium-ion batteries. Sodium is one of the most abundant elements on Earth. However, sodium's ionic volume and mass are all larger than lithium’s, making it challenging to identify a host material capable of accommodating the repeated insertion and extraction of the comparatively large sodium ions. The organic cathode material, disodium rhodizonate (Na₂C₆O₆), emerges as a promising candidate to accommodate the large sodium ions in the insertion and extraction processes with excellent cycle stability in the sodium ion batteries. One challenge for Na₂C₆O₆ is its low electronic conductivity, at only 10-9 S cm-1. Understanding the electronic conductivity of Na₂C₆O₆, used as a cathode in sodium-ion batteries, is crucial for enhancing rate capability and efficiency. Unfortunately, measuring the electronic conductivity in a porous electrode is challenging due to the need to include the conductive additives and the heterogeneity of porous electrodes. To overcome the heterogeneity of porous electrodes, we developed a modified microelectrode array to conduct simultaneous electrochemical (de)sodiation and electrical conductivity measurement on a single, micro-sized Na₂C₆O₆ particle. Our results show that the electronic conductivity of Na₂C₆O₆ increases substantially with sodium content, substantially improving the ability of this material to cycle rapidly. Our platform broadly enables the simultaneous measurement of electronic conductivity for alkali-ion battery materials at the single-particle level.

Redox-active organic materials hold great potential as electrode materials for Li-ion and next-generation batteries due to their low cost, high theoretical capacity, and synthetic tunability. Understanding charge–discharge kinetics in organic electrodes is essential for decipering their redox mechanisms and guiding rational cathode design. Operando electron paramagnetic resonance (EPR) has already shed light on two-electron lithiation/delithiation pathways but overlapping cathode- and anode-derived signals hinder quantitative analysis of radicals during cycling. Using a custom operando EPR cell that independently probes the cathode and anode, we tracked the evolution of radical speciation and concentration in tetraaminobenzoquinone (TAQ) cathodes throughout charge-discharge cycles. Our results suggested a four-electron redox sequence proceeding through consecutive single-electron transfers, each characterized by a distinct rate constant. By varying anode (Li vs Na) and tuning the cathode’s crystallinity and oxidation state, we can disentangle the respective roles of cation intercalation, structural order, and electronic configuration in dictating multi-electron kinetics.

Predicting the location of ion sites in soft electrode materials, such as molecular crystals, is challenging due to their intrinsic structural flexibility and large free volumes. Experimental techniques, such as X-ray diffraction, often struggle to accurately determine the position of active ions, including lithium-ion positions, especially given the occurrence of phase transitions or structural changes during electrochemical reactions. Accurately identifying ion locations at different state-of-charge remains crucial for understanding fundamental electrochemical reactions in electroactive materials, such as those in rechargeable batteries. We will discuss a computational strategy integrating experimentally determined organic lattice structures from diffraction experiments with first-principles calculations. Inspired by methodologies established in inorganic materials, ^1–3 we utilize the electrostatic potential and charge density information obtained from first-principles methods to locate suitable for stable ion insertion within organic lattices. We will introduce two algorithms: (i) ElectRostatic InsertioN (ERIN), which sparsely inserts ions into electrostatically favorable sites based on the electrostatic local potential. (ii) ExtRema Averaged loCal potENTial and chaRge dEnsity (RECENTRE), which identifies electrostatically stable sites by locating local extrema in the local potential and charge density fields. These algorithms enable efficient and accurate predictions of potential ion insertion sites. In this talk, we will also showcase examples that validate these methodologies. References: Rong, Z., Kitchaev, D., Canepa, P., Huang, W. & Ceder, G. An efficient algorithm for finding the minimum energy path for cation migration in ionic materials. J. Chem. Phys. 145 , 074112 (2016). Shen, J.-X., Horton, M. & Persson, K. A. A charge-density-based general cation insertion algorithm for generating new Li-ion cathode materials. Npj Comput. Mater. 6 , 161 (2020). Zimmermann, N. E. R. et al. Electrostatic Estimation of Intercalant Jump-Diffusion Barriers Using Finite-Size Ion Models. J. Phys. Chem. Lett. 9 , 628–634 (2018).

Organic cathode materials (OCMs) have received significant research interest as promising alternatives to inorganic cathodes due to their high theoretical specific capacity, tunability, and natural abundance.[1] However, the operating voltages of OCMs remain lower than those of inorganic systems, which poses a significant challenge for attaining competitive energy densities. Despite extensive research efforts, only a limited number of new OCMs have been synthesized over the past decade since experimental discovery and validation relying on chemical knowledge of experts are time-consuming. Computational chemistry calculations offer a remedy by enabling efficient exploration of vast chemical spaces and accurate prediction of electrochemical properties. In this contribution, we utilize robust high-throughput computational chemistry calculations to systematically explore an expansive design space targeting high-voltage OCMs. Leveraging chemical intuition-driven design rules, including (1) variations in the number and positioning of carbonyl redox centers, (2) strategic heteroatom (nitrogen) substitutions in the redox backbones (benzene, naphthalene, anthracene, and phenanthrene), and (3) incorporation of electron-withdrawing groups, we generate ~1M materials. We perform a two-step screening process based on molecular synthesizability and interatomic connectivity using computationally inexpensive models to rule out chemically unsound materials. Subsequently, we carry out accurate density functional theory calculations to estimate crucial properties such as reduction potentials, solvation energies, dipole moments, reactivity, and stability. The expected outcome of this high-throughput approach includes down-selection of promising high-voltage OCMs for synthesis, electrochemical testing, and future scale-up. Additionally, this study provides a library of fundamental understanding and first-principle-based design strategies of OCMs for future research endeavors. References: [1] Poizot, P.; Gaubicher, J.; Renault, S.; Dubois, L.; Liang, Y.; Yao, Y., Chemical Reviews, 2020, 120, 6490-6557. [2] Cheng, L.; Assary, R. S.; Qu, X.; Jain, A.; Ong, S. P.; Rajput, N. N.; Persson, K.; Curtiss, L. A., The Journal of Physical Chemistry Letters, 2015, 6(2), 283-291. Figure 1

Due to their elemental abundance, compositional diversity, and favorable material-level metrics, organic electrode materials (OEMs) have gained increasing attention for the development of next-generation rechargeable batteries, including Li-ion and beyond. ¹ The chemical space of OEMs comprises hundreds of molecules, most of which have been designed based on molecular intuition, prioritizing energy metrics such as redox potential and capacity while often neglecting key physicochemical properties, including electronic conductivity, solubility, and crystallinity. These properties play a crucial role in defining the charge storage mechanism, which is a fundamental factor in the efficient operation of rechargeable batteries. Charge storage in OEMs relies on charge compensation through either conversion-type reaction ^2,3 or metal-cation intercalation, ⁴ depending on the molecular structure. Each mechanism presents distinct scientific challenges and advantages that significantly impact overall battery performance. A critical question, therefore, arises: Which charge storage mechanism is most effective for organic batteries under practical conditions. We herein assess the impact of charge storage mechanism on the electrochemical performance of organic cathodes under relevant cell parameters. First, we specially designed a series of multi-electron small-molecule quinone-based cathodes with specific capacities ranging from 320 to 440 mAh g ^-1 , each operating via operating through either conversion-type or intercalation-type reaction pathway. Second, we systematically quantified the solubility of the pristine compounds and their respective lithiated intermediates in three different representative electrolyte formulations. Finaly, we analysed the impact of cathode solubility on the active material utilization as a function of electrolyte-to-cathode ratio (S/C ratio), mass-loading, and C-rate. This work provides valuable insights that can guide material design to enhance the performance of organic cathodes under practical conditions. References P. Poizot, J. Gaubicher, S. Renault, L. Dubois, Y. Liang, and Y. Yao. Chemical Reviews., 2020 , 120, 6490-6557. A. E. Lakraychi, E. S. Picton, Y. Liang, D. Shaffer, Y, Yao. ACS Energy Lett. 2023 , 8, 12, 5032–5040. A. E. Lakraychi, I. R. Udom, R. Wen, Y, Yao. ChemSusChem. 2025 , e202402779. T. Chen, H. Banda, J Wang. J. J. Oppenheim, A. Franceschi, and M Dincă. ACS Cent. Sci., 2024 , 10, 3, 569–578.

While lithium‐ion batteries have revolutionized the field of energy storage, their reliance on critical minerals such as cobalt and nickel raises significant concerns over resource availability and supply chain uncertainty. In this study, we revisit dithiin‐fused dilithium naphthazarin (5,8‐dihydroxy‐1,4‐naphthoquinone) (DNP‐Li) as a high‐voltage Li‐ion organic cathode and evaluate its performance in conjunction with localized high‐concentration electrolyte (LHCE). DNP‐Li exhibits remarkable air and thermal stability, a high operating potential of 3.55 V vs. Li⁺/Li, and a specific capacity of 232 mAh g⁻¹, positioning it as one of the most promising candidates among Li‐ion organic cathodes. Furthermore, the electrochemical behavior of DNP‐Li is strongly influenced by the electrolyte composition, giving distinct two‐plateau or four‐plateau voltage profiles accompanied by reversible or irreversible phase transitions in carbonate‐based or LHCE electrolyte formulations, respectively. The reduced solubility of DNP‐Li‐based redox intermediates in LHCE enhances cycling stability, achieving a capacity retention of 85% after 50 cycles at 0.1C and 75% after 160 cycles at 0.5C, demonstrating a significant improvement compared to the carbonate‐based electrolyte. This work highlights the critical role of solute–electrolyte interactions in modulating the electrochemical performance of multielectron small‐molecule organic cathodes, offering new pathways for advancing sustainable and high‐efficiency energy storage technologies.