Narayan, R., Laberty-Robert, C., Pelta, J., Tarascon, J. M., Dominko, R. (2021). Self-Healing: An Emerging Technology for Next-Generation Smart Batteries, Advanced Energy Materials, 2102652. DOI: 10.1002/aenm.202102652
The complex battery degradation is a result of an interplay between different processes correlated to thermodynamic, chemical and, mechanical instability of battery components. While preventive approaches have the capability to slow down or even stop the degradation, aging cannot be completely avoided since battery cells operate in different environments. Proper vectorisation of self-healing functionalities combined with sensing can significantly contribute to a higher quality and reliability with prolonged lifetime, and improved safety (QRLS).
Bitenc, J., Scafuri, A., Pirnat, K., Lozinšek, M., Jerman, I., Grdadolnik, J., ... & Dominko, R. (2021). Electrochemical Performance and Mechanism of Calcium Metal‐Organic Battery. Batteries & Supercaps, 4(1), 214-220. DOI: 10.1002/batt.202000197
A novel Ca electrolyte based on tetrakis(hexafluoroisopropyl)borate was prepared. It enables reversible stripping/deposition of metallic Ca and has a wide potential stability window. Using this electrolyte we were able to demonstrate a Ca-organic battery where poly(anthraquinone) was used as a positive electrode. IR spectroscopy used to determine the redox mechanism during cycling confirmed reversible reduction of carbonyl C=O group into alkoxide anion C–O–. This article is one of the first in the field of Ca batteries and represents high prospective of active organic materials in Ca batteries.
Robba, A., Tchernychova, E., Bitenc, J., Randon-Vitanova, A., & Dominko, R. (2021). Magnesium Insertion and Related Structural Changes in Spinel-Type Manganese Oxides. Crystals, 11(8), 984. DOI: 10.3390/cryst11080984
In this work we have used LiMn2O4 powder as the base material for probing magnesiation, cycling behavior, and structural stability/changes in (MgxLi1-x)Mn2O4 spinel cathodes in aqueous Mg(NO3)2, non-aqueous Mg(TFSI)2/diglyme and Mg(Mg(HFIP)2 − 2Al(HFIP)3/diglyme electrolytes. Although the electrochemical measurements suggested reversible magnesiation, detailed structural and analytical STEM investigations revealed the differences in the atomic structure and Mn valence of all three cathode samples upon cycling. The electrolyte influence on the structural rearrangement during Mg insertion was discussed for each of the three systems.
Zelič, K., Katrašnik, T., & Gaberšček, M. (2021). Derivation of Transmission Line Model from the Concentrated Solution Theory (CST) for Porous Electrodes. Journal of The Electrochemical Society, 168(7), 070543. DOI: 10.1149/1945-7111/ac1314
We derived a transmission line model (TLM) directly from the Newman’s concentrated solution theory for porous electrodes (CST). After discretizing the governing equations, the Nernst-Einstein and linearized Butler-Volmer equations were introduced. Finally, flux-current and concentration-charge relations together with Ohm’s law and capacitor equation were used to obtain the final set of equations. The applicability of the derived mapping was demonstrated on the practical example of a nickel manganese cobalt oxide (NMC) insertion electrode. It was shown how all the parameters of CST can be uniquely determined if the values of TLM elements are known (and vice versa).
Drvarič Talian, S., Vižintin, A., Bitenc, J., Aquilanti, G., Randon‐Vitanova, A., Gaberšček, M., & Dominko, R. (2021). Magnesium Polysulfides: Synthesis, Disproportionation, and Impedance Response in Symmetrical Carbon Electrode Cells. ChemElectroChem, 8(6), 1062-1069. DOI: 10.1002/celc.202100041
Chemical structure of magnesium polysulfides was probed with different spectroscopic techniques (NMR, ATR-IR and XANES). Successfully synthesized polysulfides enable us to perform important basic research on Mg-S batteries. Magnesium polysulfides undergo disproportionation when in solution and the bottle-neck process during the operation of Mg-S systems is the diffusion of polysufides from the bulk of the electrolyte in the separator towards the electrode surface. High polysulfide concentration catholytes could not be prepared in ether-based solvents, as the electrolyte salt(s) precipitate(s) upon the addition of magnesium polysulfides.
Moškon, J., Žuntar, J., Drvarič-Talian, S., Dominko, R., & Gaberšček, M. (2020). A powerful transmission line model for analysis of impedance of insertion battery cells: a case study on the NMC-Li system. Journal of the Electrochemical Society, 167(14), 140539. DOI: 10.1149/1945-7111/abc769
An upgraded physics-based transmission line model (TLM) describing the general impedance response of porous battery electrodes was proposed. Its suitability for interpretation of measured impedance spectra was checked on several sets of dedicated measurements employing Lithium-Nickel-Manganese-Cobalt-Oxide (NMC) and metallic lithium as electrodes. Every significant detail of all measured spectra could be successfully interpreted using the proposed transmission line model. Among others, the proposed TLM was also used for interpretation of the evolution of most important impedance features during discharge (and charge) of an NMC-Li cell using the conventional GITT-EIS protocol.
Scafuri, A., Berthelot, R., Pirnat, K., Vižintin, A., Bitenc, J., Aquilanti, G., ... & Stievano, L. (2020). Spectroscopic insights into the electrochemical mechanism of rechargeable calcium/sulfur batteries. Chemistry of materials, 32(19), 8266-8275. DOI: 10.1021/acs.chemmater.0c02074
We demonstrated reversible discharge/charge of a Ca-S battery at room temperature. The prepared Ca-S battery showed a medium-term cycling stability with low polarization. We have used a simple positive electrode made of sulfur supported on an activated carbon cloth scaffold, and a fluorinated alkoxyborate-based electrolyte. Insights into the electrochemical mechanism of the Ca-S battery were obtained with the employment of ex situ X-ray photoelectron spectroscopy and operando X-ray absorption spectroscopy.
Lindahl, N., Bitenc, J., Dominko, R., & Johansson, P. (2020). Aluminum Metal–Organic Batteries with Integrated 3D Thin Film Anodes. Advanced Functional Materials, 30(51), 2004573. DOI: 10.1002/adfm.202004573
A new 3D thin film Al anode was prepared using vapor deposition. 3D thin film Al anode together with polymer organic cathode demonstrates a significant improvement over the Al foil, which is used in current state-of-the-art Al batteries. Main improvement is in terms of the power density, which is one of the most important performance metrics for the intended application of stationary energy storage.
Mba, J. M. A., Arčon, I., Mali, G., Tchernychova, E., Witte, R., Kruk, R., ... & Dominko, R. (2020). Ceramic synthesis of disordered lithium rich oxyfluoride materials. Journal of Power Sources, 467, 228230. DOI: 10.1016/j.jpowsour.2020.228230
Two ceramic synthesis routes for the preparation of disordered lithium rich oxyfluorides were developed, each leading to a different level of doping with Li and F and different levels of cationic disorder in the structure. The obtained lithium-rich iron oxyfluorides were characterized by the Mössbauer spectroscopy, X-Ray absorption spectroscopy, NMR and TEM techniques. Successful incorporation of Li and F have been confirmed and specific capacity of the synthesized materials was in correlation with the level of disorder introduced by doping; nevertheless, oxidation state of iron in all samples was found to be very similar.
Bitenc, J., Lindahl, N., Vižintin, A., Abdelhamid, M. E., Dominko, R., & Johansson, P. (2020). Concept and electrochemical mechanism of an Al metal anode‒organic cathode battery. Energy Storage Materials, 24, 379-383. DOI: 10.1016/j.ensm.2019.07.033
Aluminium metal anode is one of the most interesting battery anode materials due to its high theoretical capacity. The main issue of Al batteries is the difficult intercalation of Al ions into inorganic hosts. In this work, the inorganic cathode was replaced by an organic material based on anthraquinone. The assembled cells displayed extremely good reversibility. Long-term capacity retention of aluminium-organic battery was improved through synthesis of polymer cathode, which enabled long-term cycling. Electrochemical mechanism of the organic cathode was studied through operando ATR-IR and ex situ XPS and SEM-EDS. The discharged organic cathode was found to be predominantly coordinated by AlCl2+ ion.
Vižintin, A., Bitenc, J., Lautar, A. K., Grdadolnik, J., Vitanova, A. R., & Pirnat, K. (2020). Redox Mechanisms in Li and Mg Batteries Containing Poly (phenanthrene quinone)/Graphene Cathodes using Operando ATR‐IR Spectroscopy. ChemSusChem, 13(9), 2328. DOI: 10.1002/cssc.202000054
PFQ/rGO composite based on poly(phenanthrene quinone) and reduced graphene oxide (rGO) had already been successfully demonstrated as a functioning active material in Li-organic battery, where it showed extremely stable cycling. In this article, we further tested this material in Mg-organic battery, achieving the capacity of 186 mAh/g and stable cycling (only 8% drop in 100 cycles). Additionally, redox mechanism during cycling was explained using operando IR spectroscopy, supported by DFT modeling and IR spectra of model compounds. We confirmed that carbonyl C=O bond is reversibly reduced to alkoxy C–O– group.
Kopač Lautar, A., Bitenc, J., Rejec, T., Dominko, R., Filhol, J. S., & Doublet, M. L. (2020). Electrolyte reactivity in the double layer in Mg batteries: An interface potential-dependent DFT study. Journal of the American Chemical Society, 142(11), 5146-5153. DOI: 10.1021/jacs.9b12474
Semsari Parapari, S., Ateba Mba, J. M., Tchernychova, E., Mali, G., Arčon, I., Kapun, G., ... & Dominko, R. (2019). Effects of a Mixed O/F Ligand in the Tavorite-Type LiVPO4O Structure. Chemistry of Materials, 32(1), 262-272. DOI: 10.1021/acs.chemmater.9b03698
To the best of our knowledge, we have for the first time synthesized a LiVPO4O-type phase with a mixed O/F ligand. Characterization of the investigated materials was performed using microscale-covering XRD, XANES, and NMR techniques as well as nanoscale spatially resolved imaging and analytical STEM techniques. Our results clearly emphasize the connection between the fluorine ligand incorporation, its local distribution, and the electrochemical properties of the material.
Drvarič Talian, S., Kapun, G., Moškon, J., Vižintin, A., Randon-Vitanova, A., Dominko, R., & Gaberšček, M. (2019). Which process limits the operation of a Li–S system?. Chemistry of Materials, 31(21), 9012-9023. DOI: 10.1021/acs.chemmater.9b03255
The impact of the solid film deposit (mainly Li2S) on the complex electrochemistry of a Li–S cell is studied in detail. Different model systems are prepared in which crucial variables such as the electrode configuration, separator type, and state of charge are varied in a systematic and controlled way. Electrochemical results are supplemented with data from microstructural analysis, in particular focused ion beam–scanning electron microscopy (FIB-SEM) imaging and X-ray diffraction analysis. We show that the growth of the surface film is more complex than generally assumed and that its defect-rich morphology hardly represents any obstacle for electrochemical reaction(s) to take place. Rather, the cell operation is limited by diffusional processes and depletion of polysulfide concentration in electrolyte.
Drvarič Talian, S., Bobnar, J., Sinigoj, A. R., Humar, I., & Gaberšček, M. (2019). Transmission line model for description of the impedance response of Li electrodes with dendritic growth. The Journal of Physical Chemistry C, 123(46), 27997-28007. DOI: 10.1021/acs.jpcc.9b05887
A general transmission line model that is able to accurately describe the measured impedance spectra of uncycled and cycled lithium electrodes is introduced. The model has all the essential features that are contained in analytical solutions for determining the impedance response of porous electrodes. In addition to that, it allows for easy coupling between the various phenomena met in lithium anodes in contact with a separator. The model is used for quantitative analysis of measured impedance spectra collected at different C-rates and after different numbers of charge–discharge cycles. Finally, several simplified schemes that allow identification of the main degradation or failure mechanism(s) occurring in cycled lithium anodes are presented.
Pirnat, K., Casado, N., Porcarelli, L., Ballard, N., & Mecerreyes, D. (2019). Synthesis of Redox Polymer Nanoparticles Based on Poly (vinyl catechols) and Their Electroactivity. Macromolecules, 52(21), 8155-8166. DOI: 10.1021/acs.macromol.9b01405
Using emulsion polymerization we prepared redox-active nanoparticles (RPN) made from two polymers: poly(4-vinyl catechol) and poly(3-vinyl catechol). The particle size was in the range of 40 – 330 nm. Their electrochemistry was tested by cyclic voltammetry using three types of electrolytes: neutral and acidic aqueous as well as acetonitrile-based. Owing to the RPN small particle size and their high theoretical capacity 394 mAh/g these RPN materials are promising candidates for active materials in organic batteries.
Bitenc, J., Vižintin, A., Grdadolnik, J., & Dominko, R. (2019). Tracking electrochemical reactions inside organic electrodes by operando IR spectroscopy. Energy Storage Materials, 21, 347-353. DOI: 10.1016/j.ensm.2019.05.038
Operando IR spectroscopy is an extremely powerful analytical tool that allows for direct visualization of IR active changes during electrochemical cycling. We have shown that analysis of operando spectra enables identification of intermediate species during charging/discharging. Comparison of the spectra in different cycles visualizes formation of passive layers. However, the operando cell still faces certain limitations, mainly limited penetration depth of approximately 1 micrometer, which can lead to measured IR spectra not revealing real-time electrochemical information in case of uneven electrochemical activity along the electrode thickness.
Li, Y., Chen, H., Lim, K., Deng, H. D., Lim, J., Fraggedakis, D., ... & Chueh, W. C. (2018). Fluid-enhanced surface diffusion controls intraparticle phase transformations. Nature materials, 17(10), 915-922. DOI: 10.1038/s41563-018-0168-4
Solid-state phase transformations enable many important technologies, including batteries, hydrogen storage, electrocatalysts and memristors. Researchers have in this study demonstrated that surface diffusion of lithium ions facilitated by solvent molecules makes LiXFePO4 a ‘three-dimensional’ conductor. Surface diffusion is a missing link that controls the phase transformation rate in LiXFePO4 and determines the current threshold between phase separation and solid solution. In other words, surface diffusion must also be considered for both mechanistic understanding and improved device performance. More broadly, the finding provides a general framework for phase transformation mechanisms in anisotropic materials.
Pirnat, K., Bitenc, J., Vižintin, A., Krajnc, A., & Tchernychova, E. (2018). Indirect synthesis route toward cross-coupled polymers for high voltage organic positive electrodes. Chemistry of Materials, 30(16), 5726-5732. DOI: 10.1021/acs.chemmater.8b02329
Based on very successful poly(1,4-anthraquinone) from the literature we developed analogous poly(phenanthrene quinone) PFQ with higher redox potential in Li-organic battery. For the synthesis of this novel polymer 6 step reaction was developed (indirect route). During polymerization, reduced graphene oxide (rGO) was added to obtain PFQ/rGO composite, which showed capacity 160 mAh/gwhen tested inside Li-organic battery. This PFQ/rGO composite exhibits extremely stable cycling with only 9% drop of capacity after 500 cycles.
Bančič, T., Bitenc, J., Pirnat, K., Kopač Lautar, A., Grdadolnik, J., Randon Vitanova A., & Dominko R. (2018). Electrochemical performance and redox mechanism of naphthalene-hydrazine diimide polymer as a cathode in magnesium battery, J. Power Sources, 395, 25-30. DOI: 10.1016/j.jpowsour.2018.05.051
High temperature stability makes polyimides promising for a variety of different application. A polymer based on naphthalene hydrazine diimide was tested in a magnesium-organic battery. The electrochemical mechanism of polyimide cathode was probed with operando ATR-IR measurements and corroborated with DFT calculations.
Vižintin, A., Guterman, R., Schmidt, J., Antonietti, M., & Dominko, R. (2018). Linear and cross-linked ionic liquid polymers as binders in lithium–sulfur batteries. Chemistry of Materials, 30(15), 5444-5450. DOI: 10.1021/acs.chemmater.8b02357
A collection of different polymeric ionic liquids (PILs) was explored as cathode binders for Li-S batteries. The PIL molecular structure, polymer backbone, and polymer architecture were found to influence the cell capacity, its cyclability, and the morphology of the cathode itself. Contrary to the traditional view of binders as merely a “glue” to hold the active material together, PIL binders take up additonal functions and play an active role during Li-S battery working operation.
Vižintin, A., Bitenc, J., Lautar, A. K., Pirnat, K., Grdadolnik, J., Stare, J., ... & Dominko, R. (2018). Probing electrochemical reactions in organic cathode materials via in operando infrared spectroscopy. Nature communications, 9(1), 1-7. DOI: 10.1038/s41467-018-03114-1
Understanding electrochemical mechanisms at play in battery cells is crucial for the future improvement of battery systems. Operando analytical methods comprise an invaluable tool for studying these mechanisms as they allow for investigating the battery cell during its operation. This work focused on probing anthraquinone cathode in lithium and magnesium battery with operando IR spectroscopy. Special pouch cell with Si wafer window was designed to enable IR measurements during the battery operation. IR spectroscopy coupled to electrochemical measurements revealed reduction of the carbonyl band in both systems. Operando measurements were complemented with theoretical calculations of IR spectra as well as the synthesis of model compounds.
Drvarič Talian, S., Jeschke, S., Vižintin, A., Pirnat, K., Arčon, I., Aquilanti, G., ... & Dominko, R. (2017). Fluorinated ether based electrolyte for high-energy lithium–sulfur batteries: Li+ solvation role behind reduced polysulfide solubility. Chemistry of Materials, 29(23), 10037-10044. DOI: 10.1021/acs.chemmater.7b03654
By employing new electrolytes, the polysulfide shuttle phenomenon, one of the main problems of lithium–sulfur (Li–S) batteries, can be significantly reduced. Here we present excellent Coulombic efficiencies as well as adequate performance of high-energy Li–S cells by the use of a fluorinated ether (TFEE) based electrolyte at low electrolyte loading. The observed altered discharge profile was investigated both by electrochemical experiments and an especially tailored COSMO-RS computational approach, while the details of the discharge mechanism were elucidated by two operando techniques: XANES and UV–vis spectroscopy. A significant decrease of polysulfide solubility compared to tetraglyme is due to different Li+ solvation mode.
Robba, A., Vižintin, A., Bitenc, J., Mali, G., Arčon, I., Kavčič, M., ... & Dominko, R. (2017). Mechanistic study of magnesium–sulfur batteries. Chemistry of Materials, 29(21), 9555-9564. DOI: 10.1021/acs.chemmater.7b03956
High capacity of magnesium metal and sulfur makes them attractive for battery electrodes. Their combination in magnesium-sulfur battery would result in high-energy density batteries and a lower cell price due to the abundance of the two elements. Using a combination of electrochemistry, X-ray diffraction and solid-state NMR we elucidated the electrochemical mechanism of magnesium-sulfur battery, which is a first step towards future improvements in their performance.
Vižintin, A., Chabanne, L., Tchernychova, E., Arčon, I., Stievano, L., Aquilanti, G., ... & Dominko, R. (2017). The mechanism of Li2S activation in lithium-sulfur batteries: Can we avoid the polysulfide formation?. Journal of Power Sources, 344, 208-217. DOI: 10.1016/j.jpowsour.2017.01.112
In this article, we report the possibility of having a direct conversion of Li2S into sulfur without detectable formation of polysulfides species. With two operando measurements, we demonstrated a direct oxidation of Li2S into sulfur accompanied by an almost negligible formation of polysulfide species at potentials above 2.5 V. Our results show the variety of first charge profiles of the Li2S oxidation mechanism and reveal the importance of ionic wiring within the used material. Additionally, we showed that the relative amount of soluble sulfur in the electrolyte influences the Li2S oxidation mechanism.
Senćanski, J., Bajuk-Bogdanović, D., Majstorović, D., Tchernychova, E., Papan, J., & Vujković, M. (2017). The synthesis of Li(CoMnNi)O2 cathode material from spent-Li ion batteries and the proof of its functionality in aqueous lithium and sodium electrolytic solutions. Journal of Power Sources, 342, 690-703. DOI: 10.1016/j.jpowsour.2016.12.115
Several spent Li-ion batteries were manually dismantled and their components uncurled and separated. The electrochemical behavior of recycled cathode materials was examined by cyclic voltammetry and chronopotentiometry in both LiNO3 and NaNO3 aqueous solutions. Its structure and morphology were characterized by XRD, Raman spectroscopy, SEM-EDS and TEM methods. The differences in the Li and Na charge storage capability were explained in terms of ion rearrangement during charging/discharging processes.
Baloch, M., Vižintin, A., Chellappan, R. K., Moškon, J., Shanmukaraj, D., Dedryvère, R., ... & Dominko, R. (2016). Application of gel polymer electrolytes based on ionic liquids in lithium-sulfur batteries. Journal of The Electrochemical Society, 163(10), A2390. DOI: 10.1149/2.1151610jes
A gel polymer electrolyte (GPE) based on polymer ionic liquid (PIL) is used in a solvent-free and in a hybrid electrolyte configuration for Li-S batteries. The solvent-free configuration showed a high discharge capacity in the first cycle and excellent Coulombic efficiency during cycling. The hybrid configuration outperforms cycling stability of the conventional configuration with a liquid electrolyte.
Pirnat, K., Mali, G., Gaberšček, M., & Dominko, R. (2016). Quinone-formaldehyde polymer as an active material in Li-ion batteries. Journal of Power Sources, 315, 169-178. DOI: 10.1016/j.jpowsour.2016.03.010
Insoluble redox active polymer was developed using easily accessible raw materials: hydroquinone, formaldehyde and hydrogen peroxide. This polymer was used as a positive electrode in a Li-organic battery where very stable capacity was observed over 200 cycles. Obtained capacity of 150 mAh/g was much lower than the theoretical 406 mAh/g and can be explained with large particle size of 2-20 µm and low electrical conductivity of the material. Higher capacity could be obtained by preparation of smaller particles and composites with electronically conductive carbon.