@article{21040, abstract = {Formation during the first cycles of Li-rich layered oxide (LRLO) cathode materials consolidates the interphase and leads to structural changes that are decisive for long-term cyclability. However, the nature and effect of the changes are material-dependent and unknown for the important class of Co-free, Ni-poor LRLOs. Here, we analyze the processes during the tailored formation procedure of a typical class member, Li1.28Ni0.15Mn0.57O2, and demonstrate that it remarkably changes lattice composition and structure as a prerequisite for stable cycling. We combine electrochemistry, operando mass spectrometry, X-ray diffraction, and X-ray absorption spectroscopy with density functional theory simulations. Activation most prominently compresses the layer spacing along the c-axis and increases reversible structural breathing. The large capacity of ∼250 mAh g–1 originates from the Ni2+/Ni4+ and O2–/O– redox couples. Electron exchange during O-redox is smeared over the entire anionic sublattice rather than localized on specific oxygen atomic sites. This redox mechanism is reversible without detrimental oxygen evolution, avoiding continued degradation common in conventional LRLOs. Sequential Ni- and O-redox during activation irreversibly distorts the coordination of the redox-inactive Mn4+ centers. This structural evolution of the MnO6 octahedra appears to enable the superior electrochemical performance of this LRLO phase. These findings define an activation pathway for the important class of Co-free, Ni-poor LRLOs, offering potential guidance for the rational design of high-performance, more sustainable cathode materials.}, author = {Busato, Matteo and Tuccillo, Mariarosaria and Celeste, Arcangelo and Tofoni, Alessandro and Silvestri, Laura and D’Angelo, Paola and Freunberger, Stefan Alexander and Brutti, Sergio}, issn = {2574-0962}, journal = {ACS Applied Energy Materials}, number = {1}, pages = {686--697}, publisher = {American Chemical Society}, title = {{Structural rearrangements of a Cobalt-free Lithium-rich layered oxide cathode during formation}}, doi = {10.1021/acsaem.5c03511}, volume = {9}, year = {2026}, } @article{21730, abstract = {Hydrogen peroxide (H2O2) is a crucial member of the reactive oxygen species (ROS) family, playing roles in cellular signalling and immune responses in human health. Moreover, it is a potential biomarker of diabetes when present in aberrant concentrations. Therefore, monitoring trace levels of H2O2 has become a research hotspot for analytical and sensor chemists. In this context, we report a rhodamine-based fluorescent probe (RN), which shows excellent fluorescent enhancement at 555 nm upon the addition of H2O2 along with a low limit of detection (LOD) of 0.67 ppm and fast response (∼2 min). The probe is highly selective for H2O2, showing no fluorescence enhancement with other ROS. RN is synthesised in a one-pot chemical reaction using rhodamine 6G (R6G) and 4,7,10-trioxa-1,13-tridecanediamine (TTDA). H2O2 detection in pre-treated milk samples proves its real-world viability. We found that RN shows low cytotoxicity, which allowed us to successfully explore its potential to monitor H2O2 generation in a diabetic L929 skin cell line and diabetic mice liver tissue. This result demonstrates promising features for assessing early diabetic progression through fluorescence imaging.}, author = {Mondal, Moumita and Ghorai, Pravat and Samadder, Asmita and Freunberger, Stefan Alexander and Banerjee, Priyabrata}, issn = {2050-7518}, journal = {Journal of Materials Chemistry B}, publisher = {Royal Society of Chemistry}, title = {{H2O2 responsive rhodamine-based probe for monitoring early-stage diabetes diagnosis}}, doi = {10.1039/d5tb02687c}, year = {2026}, } @article{20593, abstract = {“Quasi-solid-state” conversion mechanisms using sparingly solvating electrolytes (SPSEs) bridge the gap between traditional solid–liquid–solid and solid-state sulfur conversion in lithium–sulfur (Li–S) batteries. Although these terms are commonly used, their precise distinctions and impacts on key performance metrics, such as rate capability, energy density, and capacity fading, remain poorly understood. In this work, we employ operando small- and wide-angle X-ray scattering alongside cryogenic transmission electron microscopy (cryo-TEM) to compare Li–S batteries in sparingly solvating and solvating ether-based electrolytes. We find that, unlike solvating electrolytes, SPSEs lead to an extended presence of lithium sulfide during cycling, coexisting with sulfur at a 50% state of charge and beyond. In the charged state, solid sulfur is present in its amorphous form inside the carbon black nanopores. These findings indicate that the limited solubility confines polysulfides in regions near the carbon surface, where these polysulfides enable conversion between the coexisting solid discharge and charge product.}, author = {Dutta, Pronoy and Von Mentlen, Jean Marc and Mondal, Soumyadip and Kostoglou, Nikolaos and Wilts, Bodo D. and Freunberger, Stefan Alexander and Zickler, Gregor A. and Prehal, Christian}, issn = {2380-8195}, journal = {ACS Energy Letters}, pages = {5722--5732}, publisher = {American Chemical Society}, title = {{Bridging solution and solid-state mechanism: Confined quasi-solid-state conversion in Li–S batteries}}, doi = {10.1021/acsenergylett.5c02093}, volume = {10}, year = {2025}, } @article{19282, abstract = {Osmium complexes with osmium in different oxidation states (II, III, IV, and VI) have been reported to exhibit antiproliferative activity in cancer cell lines. Herein, we demonstrate unexplored opportunities offered by 187Os nuclear forward scattering (NFS) and nuclear inelastic scattering (NIS) of synchrotron radiation for characterization of hyperfine interactions and lattice dynamics in a benchmark Os(VI) complex, K2[OsO2(OH)4]. We determined the isomer shift [δ = 3.3(1) millimeters per second] relative to [OsIVCl6]2− and quadrupole splitting [ΔEQ = 12.0(2) millimeters per second] with NFS. We estimated the Lamb-Mössbauer factor [0.80(4)], extracted the density of phonon states, and carried out a thermodynamics characterization using the NIS data combined with first-principles calculations. Overall, we provide evidence that 187Os nuclear resonance scattering is a reliable technique for the investigation of hyperfine interactions and Os-specific vibrations in osmium(VI) species and is thus applicable for such measurements in osmium complexes of other oxidation states, including those with anticancer activity such as Os(III) and Os(IV).}, author = {Stepanenko, Iryna and Huang, Zhishuo and Ungur, Liviu and Bessas, Dimitrios and Chumakov, Aleksandr and Sergueev, Ilya and Büchel, Gabriel E. and Al-Kahtani, Abdullah A. and Chibotaru, Liviu F. and Telser, Joshua and Arion, Vladimir B.}, issn = {2375-2548}, journal = {Science Advances}, number = {6}, publisher = {AAAS}, title = {{187Os nuclear resonance scattering to explore hyperfine interactions and lattice dynamics for biological applications}}, doi = {10.1126/sciadv.ads3406}, volume = {11}, year = {2025}, } @phdthesis{20607, author = {Mondal, Soumyadip}, isbn = {978-3-99078-071-8}, issn = {2663-337X}, pages = {71}, publisher = {Institute of Science and Technology Austria}, title = {{Oxygen and sulfur redox : Conversion kinetics and phase equilibria}}, doi = {10.15479/AT-ISTA-20607}, year = {2025}, } @article{17468, abstract = {Oxygen redox chemistry is central to life1 and many human-made technologies, such as in energy storage2,3,4. The large energy gain from oxygen redox reactions is often connected with the occurrence of harmful reactive oxygen species3,5,6. Key species are superoxide and the highly reactive singlet oxygen3,4,5,6,7, which may evolve from superoxide. However, the factors determining the formation of singlet oxygen, rather than the relatively unreactive triplet oxygen, are unknown. Here we report that the release of triplet or singlet oxygen is governed by individual Marcus normal and inverted region behaviour. We found that as the driving force for the reaction increases, the initially dominant evolution of triplet oxygen slows down, and singlet oxygen evolution becomes predominant with higher maximum kinetics. This behaviour also applies to the widely observed superoxide disproportionation, in which one superoxide is oxidized by another, in both non-aqueous and aqueous systems, with Lewis and Brønsted acidity controlling the driving forces. Singlet oxygen yields governed by these conditions are relevant, for example, in batteries or cellular organelles in which superoxide forms. Our findings suggest ways to understand and control spin states and kinetics in oxygen redox chemistry, with implications for fields, including life sciences, pure chemistry and energy storage.}, author = {Mondal, Soumyadip and Nguyen, Huyen T.K. and Hauschild, Robert and Freunberger, Stefan Alexander}, issn = {1476-4687}, journal = {Nature}, number = {8085}, pages = {601–605}, publisher = {Springer Nature}, title = {{Marcus kinetics control singlet and triplet oxygen evolving from superoxide}}, doi = {10.1038/s41586-025-09587-7}, volume = {646}, year = {2025}, } @article{14701, author = {Archer, Lynden A. and Bruce, Peter G. and Calvo, Ernesto J. and Dewar, Daniel and Ellison, James H. J. and Freunberger, Stefan Alexander and Gao, Xiangwen and Hardwick, Laurence J. and Horwitz, Gabriela and Janek, Jürgen and Johnson, Lee R. and Jordan, Jack W. and Matsuda, Shoichi and Menkin, Svetlana and Mondal, Soumyadip and Qiu, Qianyuan and Samarakoon, Thukshan and Temprano, Israel and Uosaki, Kohei and Vailaya, Ganesh and Wachsman, Eric D. and Wu, Yiying and Ye, Shen}, issn = {1364-5498}, journal = {Faraday Discussions}, keywords = {Physical and Theoretical Chemistry}, pages = {392--411}, publisher = {Royal Society of Chemistry}, title = {{Towards practical metal–oxygen batteries: General discussion}}, doi = {10.1039/d3fd90062b}, volume = {248}, year = {2024}, } @article{14702, author = {Attard, Gary A. and Calvo, Ernesto J. and Curtiss, Larry A. and Dewar, Daniel and Ellison, James H. J. and Gao, Xiangwen and Grey, Clare P. and Hardwick, Laurence J. and Horwitz, Gabriela and Janek, Juergen and Johnson, Lee R. and Jordan, Jack W. and Matsuda, Shoichi and Mondal, Soumyadip and Neale, Alex R. and Ortiz-Vitoriano, Nagore and Temprano, Israel and Vailaya, Ganesh and Wachsman, Eric D. and Wang, Hsien-Hau and Wu, Yiying and Ye, Shen}, issn = {1364-5498}, journal = {Faraday Discussions}, keywords = {Physical and Theoretical Chemistry}, pages = {75--88}, publisher = {Royal Society of Chemistry}, title = {{Materials for stable metal–oxygen battery cathodes: general discussion}}, doi = {10.1039/d3fd90059b}, volume = {248}, year = {2024}, } @article{14733, abstract = {Redox flow batteries (RFBs) rely on the development of cheap, highly soluble, and high-energy-density electrolytes. Several candidate quinones have already been investigated in the literature as two-electron anolytes or catholytes, benefiting from fast kinetics, high tunability, and low cost. Here, an investigation of nitrogen-rich fused heteroaromatic quinones was carried out to explore avenues for electrolyte development. These quinones were synthesized and screened by using electrochemical techniques. The most promising candidate, 4,8-dioxo-4,8-dihydrobenzo[1,2-d:4,5-d′]bis([1,2,3]triazole)-1,5-diide (−0.68 V(SHE)), was tested in both an asymmetric and symmetric full-cell setup resulting in capacity fade rates of 0.35% per cycle and 0.0124% per cycle, respectively. In situ ultraviolet-visible spectroscopy (UV–Vis), nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) spectroscopies were used to investigate the electrochemical stability of the charged species during operation. UV–Vis spectroscopy, supported by density functional theory (DFT) modeling, reaffirmed that the two-step charging mechanism observed during battery operation consisted of two, single-electron transfers. The radical concentration during battery operation and the degree of delocalization of the unpaired electron were quantified with NMR and EPR spectroscopy.}, author = {Jethwa, Rajesh B and Hey, Dominic and Kerber, Rachel N. and Bond, Andrew D. and Wright, Dominic S. and Grey, Clare P.}, issn = {2574-0962}, journal = {ACS Applied Energy Materials}, keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)}, number = {2}, pages = {414--426}, publisher = {American Chemical Society}, title = {{Exploring the landscape of heterocyclic quinones for redox flow batteries}}, doi = {10.1021/acsaem.3c02223}, volume = {7}, year = {2024}, } @article{17333, abstract = {Aqueous zinc-ion batteries are attractive due to their low cost, environmental friendliness, and exceptional performance, but the latter remains poorly understood. Now, a fast catalytic step involved in oxygen redox catalysis is shown to contribute to capacity at a high rate.}, author = {Mondal, Soumyadip and Freunberger, Stefan Alexander}, issn = {2520-1158}, journal = {Nature Catalysis}, number = {7}, pages = {759--760}, publisher = {Springer Nature}, title = {{Catalysing rate and capacity}}, doi = {10.1038/s41929-024-01184-7}, volume = {7}, year = {2024}, } @article{14687, abstract = {The short history of research on Li-O2 batteries has seen a remarkable number of mechanistic U-turns over the years. From the initial use of carbonate electrolytes, that were then found to be entirely unsuitable, to the belief that (su)peroxide was solely responsible for degradation, before the more reactive singlet oxygen was found to form, to the hypothesis that capacity depends on a competing surface/solution mechanism before a practically exclusive solution mechanism was identified. Herein, we argue for an ever-fresh look at the reported data without bias towards supposedly established explanations. We explain how the latest findings on rate and capacity limits, as well as the origin of side reactions, are connected via the disproportionation (DISP) step in the (dis)charge mechanism. Therefrom, directions emerge for the design of electrolytes and mediators on how to suppress side reactions and to enable high rate and high reversible capacity.}, author = {Jethwa, Rajesh B and Mondal, Soumyadip and Pant, Bhargavi and Freunberger, Stefan Alexander}, issn = {1521-3773}, journal = {Angewandte Chemie International Edition}, keywords = {General Chemistry, Catalysis}, number = {28}, publisher = {Wiley}, title = {{To DISP or not? The far‐reaching reaction mechanisms underpinning Lithium‐air batteries}}, doi = {10.1002/anie.202316476}, volume = {63}, year = {2024}, } @article{13044, abstract = {Singlet oxygen (1O2) formation is now recognised as a key aspect of non-aqueous oxygen redox chemistry. For identifying 1O2, chemical trapping via 9,10-dimethylanthracene (DMA) to form the endoperoxide (DMA-O2) has become the mainstay method due to its sensitivity, selectivity, and ease of use. While DMA has been shown to be selective for 1O2, rather than forming DMA-O2 with a wide variety of potentially reactive O-containing species, false positives might hypothetically be obtained in the presence of previously overlooked species. Here, we first give unequivocal direct spectroscopic proof by the 1O2-specific near infrared (NIR) emission at 1270 nm for the previously proposed 1O2 formation pathways, which centre around superoxide disproportionation. We then show that peroxocarbonates, common intermediates in metal-O2 and metal carbonate electrochemistry, do not produce false-positive DMA-O2. Moreover, we identify a previously unreported 1O2-forming pathway through the reaction of CO2 with superoxide. Overall, we give unequivocal proof for 1O2 formation in non-aqueous oxygen redox and show that chemical trapping with DMA is a reliable method to assess 1O2 formation.}, author = {Mondal, Soumyadip and Jethwa, Rajesh B and Pant, Bhargavi and Hauschild, Robert and Freunberger, Stefan Alexander}, issn = {1364-5498}, journal = {Faraday Discussions}, keywords = {Physical and Theoretical Chemistry}, pages = {175--189}, publisher = {Royal Society of Chemistry}, title = {{Singlet oxygen in non-aqueous oxygen redox: Direct spectroscopic evidence for formation pathways and reliability of chemical probes}}, doi = {10.1039/d3fd00088e}, volume = {248}, year = {2024}, } @article{12737, abstract = {The substitution of heavier, more metallic atoms into classical organic ligand frameworks provides an important strategy for tuning ligand properties, such as ligand bite and donor character, and is the basis for the emerging area of main-group supramolecular chemistry. In this paper, we explore two new ligands [E(2-Me-8-qy)3] [E = Sb (1), Bi (2); qy = quinolyl], allowing a fundamental comparison of their coordination behavior with classical tris(2-pyridyl) ligands of the type [E′(2-py)3] (E = a range of bridgehead atoms and groups, py = pyridyl). A range of new coordination modes to Cu+, Ag+, and Au+ is seen for 1 and 2, in the absence of steric constraints at the bridgehead and with their more remote N-donor atoms. A particular feature is the adaptive nature of these new ligands, with the ability to adjust coordination mode in response to the hard–soft character of coordinated metal ions, influenced also by the character of the bridgehead atom (Sb or Bi). These features can be seen in a comparison between [Cu2{Sb(2-Me-8-qy)3}2](PF6)2 (1·CuPF6) and [Cu{Bi(2-Me-8-qy)3}](PF6) (2·CuPF6), the first containing a dimeric cation in which 1 adopts an unprecedented intramolecular N,N,Sb-coordination mode while in the second, 2 adopts an unusual N,N,(π-)C coordination mode. In contrast, the previously reported analogous ligands [E(6-Me-2-py)3] (E = Sb, Bi; 2-py = 2-pyridyl) show a tris-chelating mode in their complexes with CuPF6, which is typical for the extensive tris(2-pyridyl) family with a range of metals. The greater polarity of the Bi–C bond in 2 results in ligand transfer reactions with Au(I). Although this reactivity is not in itself unusual, the characterization of several products by single-crystal X-ray diffraction provides snapshots of the ligand transfer reaction involved, with one of the products (the bimetallic complex [(BiCl){ClAu2(2-Me-8-qy)3}] (8)) containing a Au2Bi core in which the shortest Au → Bi donor–acceptor bond to date is observed.}, author = {García-Romero, Álvaro and Waters, Jessica E. and Jethwa, Rajesh B and Bond, Andrew D. and Colebatch, Annie L. and García-Rodríguez, Raúl and Wright, Dominic S.}, issn = {1520-510X}, journal = {Inorganic Chemistry}, number = {11}, pages = {4625--4636}, publisher = {American Chemical Society}, title = {{Highly adaptive nature of group 15 tris(quinolyl) ligands─studies with coinage metals}}, doi = {10.1021/acs.inorgchem.3c00057}, volume = {62}, year = {2023}, } @article{13041, abstract = {A series of triarylamines was synthesised and screened for their suitability as catholytes in redox flow batteries using cyclic voltammetry (CV). Tris(4-aminophenyl)amine was found to be the strongest candidate. Solubility and initial electrochemical performance were promising; however, polymerisation was observed during electrochemical cycling leading to rapid capacity fade prescribed to a loss of accessible active material and the limitation of ion transport processes within the cell. A mixed electrolyte system of H3PO4 and HCl was found to inhibit polymerisation producing oligomers that consumed less active material reducing rates of degradation in the redox flow battery. Under these conditions Coulombic efficiency improved by over 4 %, the maximum number of cycles more than quadrupled and an additional theoretical capacity of 20 % was accessed. This paper is, to our knowledge, the first example of triarylamines as catholytes in all-aqueous redox flow batteries and emphasises the impact supporting electrolytes can have on electrochemical performance.}, author = {Farag, Nadia L. and Jethwa, Rajesh B and Beardmore, Alice E. and Insinna, Teresa and O'Keefe, Christopher A. and Klusener, Peter A.A. and Grey, Clare P. and Wright, Dominic S.}, issn = {1864-564X}, journal = {ChemSusChem}, number = {13}, publisher = {Wiley}, title = {{Triarylamines as catholytes in aqueous organic redox flow batteries}}, doi = {10.1002/cssc.202300128}, volume = {16}, year = {2023}, } @article{12208, abstract = {The inadequate understanding of the mechanisms that reversibly convert molecular sulfur (S) into lithium sulfide (Li2S) via soluble polysulfides (PSs) formation impedes the development of high-performance lithium-sulfur (Li-S) batteries with non-aqueous electrolyte solutions. Here, we use operando small and wide angle X-ray scattering and operando small angle neutron scattering (SANS) measurements to track the nucleation, growth and dissolution of solid deposits from atomic to sub-micron scales during real-time Li-S cell operation. In particular, stochastic modelling based on the SANS data allows quantifying the nanoscale phase evolution during battery cycling. We show that next to nano-crystalline Li2S the deposit comprises solid short-chain PSs particles. The analysis of the experimental data suggests that initially, Li2S2 precipitates from the solution and then is partially converted via solid-state electroreduction to Li2S. We further demonstrate that mass transport, rather than electron transport through a thin passivating film, limits the discharge capacity and rate performance in Li-S cells.}, author = {Prehal, Christian and von Mentlen, Jean-Marc and Drvarič Talian, Sara and Vizintin, Alen and Dominko, Robert and Amenitsch, Heinz and Porcar, Lionel and Freunberger, Stefan Alexander and Wood, Vanessa}, issn = {2041-1723}, journal = {Nature Communications}, keywords = {General Physics and Astronomy, General Biochemistry, Genetics and Molecular Biology, General Chemistry, Multidisciplinary}, publisher = {Springer Nature}, title = {{On the nanoscale structural evolution of solid discharge products in lithium-sulfur batteries using operando scattering}}, doi = {10.1038/s41467-022-33931-4}, volume = {13}, year = {2022}, } @article{12227, abstract = {Polydicyclopentadiene (pDCPD), a thermoset with excellent mechanical properties, has enormous potential as a lightweight, tough, and stable matrix material owing to its highly cross-linked macromolecular network. This work describes generating pDCPD-based foams and hierarchically porous carbons derived therefrom by combining ring-opening metathesis polymerization (ROMP) of DCPD, high internal phase emulsions (HIPEs) as structural templates, and subsequent carbonization. The structure and function of the carbon foams were characterized and discussed in detail using scanning electron, transmission electron, or atomic force microscopy (SEM, TEM, AFM), electron energy-loss spectroscopy (TEM-EELS), N2 sorption, and analyses of electrical conductivity as well as mechanical properties. The resulting materials exhibited uniform, shape-retaining shrinkage of only ∼1/3 after carbonization. No structural failure was observed even when the pDCPD precursor foams were heated to 1400 °C. Instead, the high porosity, void size, and 3D interconnectivity were fully preserved, and the void diameters could be adjusted between 87 and 2.5 μm. Moreover, foams have a carbon content >97%, an electronic conductivity of up to 2800 S·m–1, a Young’s modulus of up to 2.1 GPa, and a specific surface area of up to 1200 m2·g–1. Surprisingly, the pDCPD foams were carbonized into shapes other than monoliths, such as 10’s of micron thick membranes or foamy coatings adhered to a metal foil or grid substrate. The latter coatings even adhere upon bending. Finally, as a use case, carbonized foams were applied as porous cathodes for Li–O2 batteries where the foams show a favorable combination of porosity, active surface area, and pore size for outstanding capacity.}, author = {Kovačič, Sebastijan and Schafzahl, Bettina and Matsko, Nadejda B. and Gruber, Katharina and Schmuck, Martin and Koller, Stefan and Freunberger, Stefan Alexander and Slugovc, Christian}, issn = {2574-0962}, journal = {ACS Applied Energy Materials}, keywords = {Electrical and Electronic Engineering, Materials Chemistry, Electrochemistry, Energy Engineering and Power Technology, Chemical Engineering (miscellaneous)}, number = {11}, pages = {14381--14390}, publisher = {American Chemical Society}, title = {{Carbon foams via ring-opening metathesis polymerization of emulsion templates: A facile method to make carbon current collectors for battery applications}}, doi = {10.1021/acsaem.2c02787}, volume = {5}, year = {2022}, } @article{10813, abstract = {Redox mediators could catalyse otherwise slow and energy-inefficient cycling of Li–S and Li–O2 batteries by shuttling electrons or holes between the electrode and the solid insulating storage materials. For mediators to work efficiently they need to oxidize the solid with fast kinetics but with the lowest possible overpotential. However, the dependence of kinetics and overpotential is unclear, which hinders informed improvement. Here, we find that when the redox potentials of mediators are tuned via, for example, Li+ concentration in the electrolyte, they exhibit distinct threshold potentials, where the kinetics accelerate several-fold within a range as small as 10 mV. This phenomenon is independent of types of mediator and electrolyte. The acceleration originates from the overpotentials required to activate fast Li+/e− extraction and the following chemical step at specific abundant surface facets. Efficient redox catalysis at insulating solids therefore requires careful consideration of the surface conditions of the storage materials and electrolyte-dependent redox potentials, which may be tuned by salt concentrations or solvents.}, author = {Cao, Deqing and Shen, Xiaoxiao and Wang, Aiping and Yu, Fengjiao and Wu, Yuping and Shi, Siqi and Freunberger, Stefan Alexander and Chen, Yuhui}, issn = {2520-1158}, journal = {Nature Catalysis}, keywords = {Process Chemistry and Technology, Biochemistry, Bioengineering, Catalysis}, pages = {193--201}, publisher = {Springer Nature}, title = {{Threshold potentials for fast kinetics during mediated redox catalysis of insulators in Li–O2 and Li–S batteries}}, doi = {10.1038/s41929-022-00752-z}, volume = {5}, year = {2022}, } @article{12065, abstract = {Capacity, rate performance, and cycle life of aprotic Li–O2 batteries critically depend on reversible electrodeposition of Li2O2. Current understanding states surface-adsorbed versus solvated LiO2 controls Li2O2 growth as surface film or as large particles. Herein, we show that Li2O2 forms across a wide range of electrolytes, carbons, and current densities as particles via solution-mediated LiO2 disproportionation, bringing into question the prevalence of any surface growth under practical conditions. We describe a unified O2 reduction mechanism, which can explain all found capacity relations and Li2O2 morphologies with exclusive solution discharge. Determining particle morphology and achievable capacities are species mobilities, true areal rate, and the degree of LiO2 association in solution. Capacity is conclusively limited by mass transport through the tortuous Li2O2 rather than electron transport through a passivating Li2O2 film. Provided that species mobilities and surface growth are high, high capacities are also achieved with weakly solvating electrolytes, which were previously considered prototypical for low capacity via surface growth.}, author = {Prehal, Christian and Mondal, Soumyadip and Lovicar, Ludek and Freunberger, Stefan Alexander}, issn = {2380-8195}, journal = {ACS Energy Letters}, number = {9}, pages = {3112--3119}, publisher = {American Chemical Society}, title = {{Exclusive solution discharge in Li-O₂ batteries?}}, doi = {10.1021/acsenergylett.2c01711}, volume = {7}, year = {2022}, } @article{9113, abstract = {“Hydrogen economy” could enable a carbon-neutral sustainable energy chain. However, issues with safety, storage, and transport of molecular hydrogen impede its realization. Alcohols as liquid H2 carriers could be enablers, but state-of-the-art reforming is difficult, requiring high temperatures >200 °C and pressures >25 bar, and the resulting H2 is carbonized beyond tolerance levels for direct use in fuel cells. Here, we demonstrate ambient temperature and pressure alcohol reforming in a fuel cell (ARFC) with a simultaneous electrical power output. The alcohol is oxidized at the alkaline anode, where the resulting CO2 is sequestrated as carbonate. Carbon-free H2 is liberated at the acidic cathode. The neutralization energy between the alkaline anode and the acidic cathode drives the process, particularly the unusually high entropy gain (1.27-fold ΔH). The significantly positive temperature coefficient of the resulting electromotive force allows us to harvest a large fraction of the output energy from the surrounding, achieving a thermodynamic efficiency as high as 2.27. MoS2 as the cathode catalyst allows alcohol reforming even under open-air conditions, a challenge that state-of-the-art alcohol reforming failed to overcome. We further show reforming of a wide range of alcohols. The ARFC offers an unprecedented route toward hydrogen economy as CO2 is simultaneously captured and pure H2 produced at mild conditions.}, author = {Manzoor Bhat, Zahid Manzoor and Thimmappa, Ravikumar and Dargily, Neethu Christudas and Raafik, Abdul and Kottaichamy, Alagar Raja and Devendrachari, Mruthyunjayachari Chattanahalli and Itagi, Mahesh and Makri Nimbegondi Kotresh, Harish and Freunberger, Stefan Alexander and Ottakam Thotiyl, Musthafa }, issn = {2168-0485}, journal = {ACS Sustainable Chemistry and Engineering}, number = {8}, pages = {3104--3111}, publisher = {American Chemical Society}, title = {{Ambient condition alcohol reforming to hydrogen with electricity output}}, doi = {10.1021/acssuschemeng.0c07547}, volume = {9}, year = {2021}, } @article{9301, abstract = {Electrodepositing insulating lithium peroxide (Li2O2) is the key process during discharge of aprotic Li–O2 batteries and determines rate, capacity, and reversibility. Current understanding states that the partition between surface adsorbed and dissolved lithium superoxide governs whether Li2O2 grows as a conformal surface film or larger particles, leading to low or high capacities, respectively. However, better understanding governing factors for Li2O2 packing density and capacity requires structural sensitive in situ metrologies. Here, we establish in situ small- and wide-angle X-ray scattering (SAXS/WAXS) as a suitable method to record the Li2O2 phase evolution with atomic to submicrometer resolution during cycling a custom-built in situ Li–O2 cell. Combined with sophisticated data analysis, SAXS allows retrieving rich quantitative structural information from complex multiphase systems. Surprisingly, we find that features are absent that would point at a Li2O2 surface film formed via two consecutive electron transfers, even in poorly solvating electrolytes thought to be prototypical for surface growth. All scattering data can be modeled by stacks of thin Li2O2 platelets potentially forming large toroidal particles. Li2O2 solution growth is further justified by rotating ring-disk electrode measurements and electron microscopy. Higher discharge overpotentials lead to smaller Li2O2 particles, but there is no transition to an electronically passivating, conformal Li2O2 coating. Hence, mass transport of reactive species rather than electronic transport through a Li2O2 film limits the discharge capacity. Provided that species mobilities and carbon surface areas are high, this allows for high discharge capacities even in weakly solvating electrolytes. The currently accepted Li–O2 reaction mechanism ought to be reconsidered.}, author = {Prehal, Christian and Samojlov, Aleksej and Nachtnebel, Manfred and Lovicar, Ludek and Kriechbaum, Manfred and Amenitsch, Heinz and Freunberger, Stefan Alexander}, issn = {1091-6490}, journal = {Proceedings of the National Academy of Sciences of the United States of America}, keywords = {small-angle X-ray scattering, oxygen reduction, disproportionation, Li-air battery}, number = {14}, publisher = {National Academy of Sciences}, title = {{In situ small-angle X-ray scattering reveals solution phase discharge of Li–O2 batteries with weakly solvating electrolytes}}, doi = {10.1073/pnas.2021893118}, volume = {118}, year = {2021}, }