Passed Seminars: Speaker: Sergey Marshenya, PhD student: Materials Science and Engineering, Center for Energy Science and Technology, Skoltech. Title: Towards new solid electrolytes for all solid-state batteries Abstract: Solid-state batteries are regarded as one of the most promising technologies for further battery development. Coupling solid-electrolytes with post-lithium batteries allows to combine the benefits of both. There are several most studied solid ion conductors for sodium and potassium, and all of them have their own drawbacks; therefore, the synthesis and investigation of new kinds of solid conductors is an important task. In the present work, the synthesis, structure, and transport properties of new meta-stable sodium and potassium ion conductors are described. Langbeinite-type NaZr2(PO4)3 shows 10-6 Sm/cm sodium-ion conductivity at 200˚C with an activation energy of 0.44 eV. At the same time, NaGaPO4F with KTiOPO4 (KTP)-type structure shows similar activation energy ~0.5 eV derived by the solid-state NMR technique. Replacement of gallium by scandium allows to increase the unit cell to be able to conduct potassium ions along three dimensions, making the KScPO4F a rare example of a 3D potassium ion conductor, with BVEL calculated activation energy of 0.25 eV along c-axis and 0.89 eV along the b and the c axes showing 2.2•10-6 Sm/cm at room temperature. In this talk, the synthesis route, including ion-exchange and hydrothermal synthesis, structural features, and transport properties will be discussed in detail. Date: May 15, 2024 Time: 16:00-17:00 Speaker: Mikhail Agapkin, PhD-3: Materials Science and Engineering, Center for Energy Science and Technology, Skoltech. Title: An advanced method of creating full-active anodes for sodium-ion batteries and electrolytes for them Abstract: Lithium-ion batteries currently lead the energy storage device industry. However, the limited availability of lithium resources has driven the exploration of alternative energy storage technologies. Sodium-ion batteries emerge as a viable alternative due to their potential in various applications. Viable candidates for anode materials include Bi, Ge, Pb, Sb, and Sn, which are used in alloying/dealloying processes. Bi and Pb are particularly noteworthy due to their low toxicity, affordability, and availability. Nonetheless, these materials are prone to significant volume expansion and rapid degradation caused by loss of contact. A prevalent strategy to mitigate these issues involves the synthesis of nanoscale metal particles through physical vapor deposition (PVD). This method advantageously eliminates the need for binders or carbon black, allowing the electrode to operate without “dead weight”. As another advantage, the high energy associated with PVD evaporation and high deposition rates leads to formation of the nanometer-scale particles. Lack of the suitable electrolytes for such materials urge to search for alternative electrolyte systems. Ethers, particularly diglyme, are often considered as the prospective ones due to a good cycling results. This study explores the deposition of Bi and Pb films using PVD through the thermoevaporation technique. Сycledn coin-type cells against sodium metal, these anodes approach theoretical capacities at 0.1C rate and exhibit robust performance over 1000 cycles at a 1C rate. Full cells assembled with NaSICON as a cathode, delivered the initial capacity of 95 mAh/g at a 0.1C rate and stable cycling at 1C with capacity retention approximately 82% after 500 cycles. Furthermore, the performance of the cells was investigated under low temperature conditions down to -20 оС. Additionally, investigation of the conductivity and viscosity for the prospective electrolytes was held. The performance test for these electrolytes were conducted in coin cells versus sodium metal with high capacity retention up to 5% after 1000 cycles at 1C rate. Date: April 17, 2024 Time: 16:00-17:00 Speaker: Aleksandra Boldyreva, a postdoc researcher from the Energy Center who specializes in Perovskite photovoltaics and a co-founder of the Skoltech-born startup “Sunsense”. Title: Perovskite solar cells for space: Prospects and limitations Abstract: Perovskite solar cells is a 3rd generation photovoltaic technology with remarkably high power conversion efficiencies and a simple fabrication process. Solar cells based on perovskite materials can be semitransparent which makes them great candidates for multijunction tandems, which can be used, not only in terrestrial applications but also for the space industry. In this talk, I will explain, why this technology has great potential for space applications, and what are the main factors affecting solar cell stability in space with a particular focus on the impact of hard ionization, such as gamma rays. Date: April 3, 2024 Time: 16:00-17:00 Speaker: Ivan Moiseev, PhD-4: Materials Science and Engineering, Center for Energy Science and Technology, Skoltech. Title: Crystal structure of Mg-substituted layered Ni-rich cathode materials for Li-ion batteries Abstract: Layered transition metal oxides (TM) LiNi2/3+xMn4+yCo3+zO2 with an increased nickel content (x ≥ 0.6, Ni-rich NMCs) are considered promising cathode materials for new-generation Li-ion batteries. However, their wide practical application is limited due to the rapid decrease in specific capacity during prolonged electrochemical cycling. At the same time, the mechanical integrity of the cathode is degraded due to particle cracking, while the penetration of electrolyte through microcracks into the particles accelerates the process of material degradation. Chemical modification of the cation sublattice is a promising approach for solving the problem of irreversible structural changes that occur during electrochemical cycling. Of particular interest is the modification of the crystal structure by magnesium (rMg2+=0.72 Å), which can occupy both lithium positions (rLi+=0.76 Å) and TM positions (rNi2+=0.69 Å, rMn4+=0.53 Å, rCo3+=0.61 Å). However, studies of cationic substitution of magnesium in Ni-rich NMCs do not provide comprehensive information on the exact positions of magnesium in the NMC structure [1]. In our research, Ni-rich NMCs were synthesized in the form of single crystal particles via flux-growth technique with different Mg content Li(Ni0.6Mn0.2Co0.2)1-xMgxO2 (x=0, 0.05 and 0.1) in the structure. Crystal structure of Ni-rich NMCs (e.g., gr. R-3m) was refined by the joint Rietveld method based on powder synchrotron X-ray and neutron diffraction data and confirmed with high-resolution EDX-STEM technique. Based on crystal chemistry of Mg-substituted Ni-rich NMCs we plan to propose a mechanism to stabilize the structure during cycling and associate the electrochemical behaviour with the crystal structure. References: Date: February 7, 2024 Time: 16:00-17:00 Speaker: Pavel Sinitsyn, PhD-3: Materials Science and Engineering, Center for Energy Science and Technology, Skoltech. Title: Performance of Ni-Fe catalysts with different structural types in oxygen evolution reaction Abstract: Hydrogen production using water electrolysis with an anion exchange membrane (AEM), a pure water feed and cheap components such as platinum group metal-free catalysts can challenge proton exchange membrane (PEM) electrolysis systems as the state of the art. Non noble metal based electrocatalysts have received extensive interest in the development of AEM electrolyzers due to their cheaper cost and long-term stability [1,2]. This report demonstrates the investigation of influence of pristine structure of catalytic materials used in oxygen evolution reaction condition. During the presentation we will discuss structural and electrochemical features of the three target electrochemically active materials: perovskite LaNi0.45Fe0.55O3, spinel Ni(Ni0.35Fe1.65)O4 and bimetallic compound Ni0.45Fe0.55 which were obtained using ultrasonic spray-pyrolysis technique. References: Date: March 06, 2024 Time: 16:00-17:00 Place: ONLINE https://vc.skoltech.ru/b/ser-sff-ub0-ltz Speaker: Artem Dembitskiy, Research Intern, Center for Energy Science and Technology, Skoltech. Title: Computational study of NaGaPO4F ionic conductor Abstract: Ionic conductors are used in various technologies – batteries, memristors, solid oxide fuel cells, gas sensors, etc1,2. Advancement of these technologies relies on improving the properties of existing functional materials or discovering new ones with better performance. This report presents the computational study of the stability, electrochemical window, and Na-ion conductivity of the novel NaGaPO4F ionic compound3. According to the density functional theory calculations, the activation barrier of Na+ vacancy migration is 0.22 eV. Molecular dynamics simulations with moment tensor potentials4 revealed two different Na+ migration mechanisms depending on Na vacancy concentration. The obtained results are in qualitative agreement with the experimental evaluation of Na+ mobility via nuclear magnetic resonance spectroscopy. The applicability of the material as a solid electrolyte for all-solid-state Na-ion batteries will be discussed. References Date: February 21, 2024 Time: 16:00-17:00 Speaker: Alexander Golubnichiy, PhD-3: Materials Science and Engineering, Center for Energy Science and Technology, Skoltech. Title: Influence of various synthetic approaches on LLZO-cathode interaction during all-solid-state battery fabrication Abstract: The next generation of all-solid-state lithium-ion batteries rely on the use of solid electrolytes which increases the energy density and safety of the battery. Li7La3Zr2O12 (LLZO) with a cubic garnet structure is considered as a promising material for use in solid-state batteries since it has high ionic conductivity (up to 10-3 S/cm) [1] and a wide window of stability of operating potentials (0.05 – 5 V) [2]. The vast majority of works devoted to the synthesis of all-solid-state batteries use an approach in which ceramic tablets sintered at high (1200 °C) temperatures are subjected to subsequent mechanical grinding to 100 μm thick membranes. High energy consumption during sintering and the loss of a significant part of the material during thinning make this method of producing a battery economically unprofitable. At the same time, the upscaling of such a synthesis scheme is limited by the difficulty of obtaining defect-free tablets of large diameters. Recently, new synthetic approaches have been proposed for the formation of LLZO thin films. One of these approaches is the sequential deposition synthesis (SDS), which is to spray a solution of lithium, lanthanum and zirconium nitrates onto a heated substrate and subsequent high-temperature LLZO synthesis in an oxygen atmosphere [3]. Using this method makes it possible to obtain films with a thickness of 10 µm. Also, additional advantage is the reduction in the synthesis temperature of the cubic phase LLZO from 1200 to 750 °C. Another approach is to spray a suspension of a pre-synthesized LLZO phase and subsequent ultrafast high-temperature sintering (UHS) at a temperature of 1500 °C [4]. By combining high temperatures and heating rates, it is possible to achieve high density films while maintaining the lithium content of LLZO. During this presentation we will discuss the use of SDS and UHS methods when applying LLZO coating to cathode material. Ni-rich LiNi0.6Mn0.2Co0.2O2 (NMC622) and Li-rich Li1.2Ni0.2Mn0.6O2 layered oxides were used as the cathode material substrate. The microstructure and phase composition of the resulting LLZO thin film will be presented. The influence of synthesis parameters, as well as the composition of the cathode substrate on the formation of non-conducting phases is to be discussed. References Date: February 7, 2024 Time: 16:00-17:00 Speaker: Nataliia Tarasova, a deputy director and leading researcher at the Institute of High Temperature Electrochemistry of the Ural Branch of the Russian Academy of Sciences, Yekaterinburg, and a teaching-oriented professor of chemistry at the Institute of Natural Sciences and Mathematics of the Ural Federal University, Yekaterinburg. Title: Development of Materials, Technologies and Devices for Hydrogen Energy at the Institute of High Temperature Electrochemistry Abstract: Modern humanity is now facing many challenges, such as declining reserves of fossil energy resources and the rising price for fossil fuels, climate change and the increasing number of respiratory diseases. Therefore, there is an urgent need to create advanced energy materials and technologies to support a sustainable development of renewable energy systems. Hydrogen energy due to eco-friendliness and high efficiency has high priority among other renewable energy systems. Joint research in the fields of inorganic materials science and energy engineering allowed creating devices for hydrogen production, i.e., protonic ceramic electrolysis cells, and devices, where hydrogen is used as a fuel, i.e., protonic ceramic fuel cells. These devices require different types of components: interconnectors (metals), glass sealants, ceramic electrode and electrolyte materials. In the present talk, we will discuss the latest achievements in materials, technologies and devices for hydrogen energy developed at the Institute of High Temperature Electrochemistry. Date: December 13, 2023 Time: 16:00-17:00 Speaker: Svetlana Lipovskikh, Research Scientist, Center for Energy Science and Technology, Skoltech. Title: Electron Tomography as a Powerful Tool for 3D Visualization of Materials Abstract: Conventional transmission electron microscopy (TEM) addresses to a wide range of materials properties in two-dimensional space at sub-angstrom scale. In some cases, it allows us to predict properties of the investigated three-dimensional objects. However, some materials require a three-dimensional characterization in order to investigate certain properties such as morphology of nanoparticles, grains, pores and other substructures in particles, films and bulk materials, core-shell structures, etc. Tomography is a method of obtaining higher dimensionality results from lower dimensionality data. Conventional techniques for 3D tomography of materials are high-resolution x-rays tomography and FIB-SEM three-dimensional tomography. The resolution of the first method is only several hundreds of nm. The second method is destructive and provides resolution of several tens of nm. Thus, a combination of sub-angstrom resolution of ordinary 2D scanning transmission electron microscopy (STEM) and tomography potentially provides a great advantage. This powerful combination is known as 3D STEM tomography. In my talk, I will focus on basic principles of 3D STEM tomography, requirements to the samples, sample preparation, main steps of the experiment as well as to the applications, advantages and limitations of the technique. I will also demonstrate a variety of practical examples. Additionally, I will focus on EDX tomography, recently realized at CEST. All this work is performed directly on-site at Skoltech in the Advanced Imaging Core Facility lab. Date: November 29, 2023 Time: 16:00-17:00 Speaker: Eugene Nazarov, Skolkovo Institute of Science and Technology, PhD-4: Materials Science and Engineering, Center for Energy Science and Technology. Title: Three-dimensional modification of triphylite-type cathode materials Abstract: Despite the intensive research and successful commercialization of LiFePO4 (LFP) triphylite-structure cathode material for Li-ion batteries (LIBs), the modification of the production process as well as material’s functional properties is necessary for the implementation in high-energy areas. The attention of the research community is focused to the increase of operational properties of the material such as specific capacity, working potential and cycle life. Among all the existing approaches it is worth mentioning the defect structure design, substitution of Fe by higher RedOx potential 3-d metals, electronic conductivity enhancement and microstructure control for the production of microspherical particles. The report will include all the mentioned modifications and their impact on the properties of LiFe0.5Mn0.5PO4 (LFMP) as a promising next-generation triphylite-type cathode material. Defect chemistry modification will outline the production of a “Li-rich” material with an extended solid solution region of the Li+ de/intercalation mechanism. The crystal structure of the material was precisely refined based on the joint neutron and synchrotron diffraction data and supported with Mössbauer spectroscopy experiment. The refined chemical composition was Li1.07(2)Fe0.456(3)Mn0.473(2)PO4. The Li+ de/intercalation mechanism was established using operando synchrotron X-ray powder diffraction. It was found out that the solid solution dominates during the charge and discharge processes. The material demonstrates decent electrochemical performance and exhibit over 158 mAh·g-1 at C/10 and 120 mAh·g-1 with capacity retention of 84±4% after 500 cycles at 10C. The surface modification allows increasing the cycle-life even more due to the application of polyacrylonitrile (PAN) as a carbon coating precursor. The presence of cyano groups detected in the annealed carbon and resulting LFMP/C composite by FTIR spectroscopy is responsible for the tight adhesion between the conductive layer and hydroxyl-terminated surface of the cathode. The resulted composite retains about 78±2% of the initial specific capacity after 1000 cycles of a combined 5-10C cycling protocol which is 40% higher compared to the conventional glucose-derived carbon coating. The reason behind such a dramatic difference is a lower charge transfer resistance of the PAN-obtained composite during both Fe and Mn transitions. For the microspherical production of LFMP, a dittmarite-type precursor (NH4Fe0.5Mn0.5PO4·H2O) was synthesized by a co-precipitation technique followed by mild solvothermal treatment. The morphology of the as-prepared precursor remains unchanged for the final LFMP and represents microspheres with mean particles diameter of 20-30 µm and tap density of 1.56 g·cm-1. The technology makes it possible to reduce the total Li consumption during the material’s production and eliminate the impact of antisite defects on the materials’ electrochemical performance. The obtained material exhibits more than 145 mAh·g-1 and 95 mAh·g-1 at C/10 and 5C current density. The materials retain more than 85% of initial discharge capacity after 300 cycles at 5C-rate. To sum up, the outlined modifications allow diminishing the most well-known triphylite-type materials drawbacks such as predominantly two-phase Li+ de/intercalation mechanism and low electronic conductivity, and preserving high stability of the materials. In this talk we will discuss the attempts towards practical implementation of LFMP as a cathode material for high-energy LIBs and possible up-scaling routes for semi-industrial applications. Date: October 04, 2023 Time: 16:00-17:00 Speaker: Semyon Shraer, Skolkovo Institute of Science and Technology, PhD-2: Materials Science and Engineering, Center for Energy Science and Technology. Title: A new polymorph of NaVOPO4 as a prospective positive electrode material for Na-ion batteries Abstract: Within last decade fluorine-containing vanadium-based polyanion materials have earned a huge recognition for utilization in sodium-ion batteries as high-energy positive electrodes. However, the presence of fluorine in material production imposes safety issues due to the toxic and corrosive nature of associated reagents or by-products. Additionally, the fluorine-strengthened inductive effect often leads to exceedingly high upper potential cutoff provoking severe electrolyte decomposition, thus hindering long-term performance of the electrode material. A fluorine-to-oxygen substitution seems to be a way out, and a material with general formula of NaVOPO4 is the most attractive due to its high theoretical capacity (145 mAh g-1) and expected decent average voltage. In this work a new fluorine-free member of a KTiOPO4-type structured materials family, NaVOPO4, was put forward with detailed investigation of its electrochemical properties. Single-phase KTP-NaVOPO4 was synthesized via a facile two-step approach similar to that proposed earlier by our group with solid-state ion exchange using hydrothermally synthesized NH4VOPO4. Polyacrylonitrile was used as a carbon source for composite material preparation. Synchrotron X-ray diffraction patterns were fully indexed in the Pna21 space group confirmed by electron diffraction, followed by crystal structure refinement using the Rietveld method. Chemical composition was confirmed using spectroscopic and microscopic methods including ATR-FTIR and EPR spectroscopies and TEM-EDX. When tested in coin-type cells versus sodium metal on anode, NaVOPO4/C demonstrates 110 mAh/g at 0.1C rate and maintains a decent 75% of practical specific capacity at 40C, partially thanks to diffusion coefficients of sodium ions being in the range of 1⸱10 11 – 2.5⸱10 11 cm2/s. The material exhibits excellent capacity retention with only 26% and 13% discharge capacity fading after 1000 cycles at 0.5C and 2C respectively. The cell volume variation of NaVOPO4 amounts to 2.4%, which is exceptionally small, indicating a major stiffness of this framework, thus opening up opportunities for volume expansion-sensitive applications such as all-solid-state Na-ion batteries. Time: 16:00-17:00 Speaker: Elena Orlova, Skolkovo Institute of Science and Technology, PhD-3: Materials Science and Engineering, Center for Energy Science and Technology. Title: High-energy-density cathode materials for Li-ion batteries based on modified layered transition metal oxides Ni-rich NMC Abstract: Ni-rich Ni, Mn and Co transition metal oxides are considered the most promising cathode materials for efficient Li-ion batteries as they deliver enhanced discharge capacity. Addressing their electrochemical cycling stability issues, a great variety of modification routes were recently elaborated, albeit they provide mostly “trade-off” solutions, where increase of cycle life ends up in capacity decrease. In the present work, modification of grain boundaries via Li-conductive solid electrolytes, controlled change of microstructure through boron addition and microwave-assisted hydrothermal synthesis of space-filler cathode material were used to develop high-energy-density Ni-rich NMC cathode materials for Li-ion batteries to improve electrochemical properties such as capacity, stability, and energy density. A particular attention was paid to Ni2+/Li+ cation disordering and its assessment approaches, where new techniques such as electron diffraction tomography and quantitative analysis of atomic-resolution images using model-based parameter estimation were applied for Ni-rich NMCs materials for the first time. The characterization of electrochemical properties was conducted for modified samples, revealing substantial improvement of capacity retention over prolonged cycling up to 10-15% with decent maintenance of discharge capacity at different current densities. The grain boundaries engineering’s positive impact is associated with enhancement of mechanical integrity of cathode materials and increase of intra-grain Li+ diffusion due to incorporation of amorphous Li2SO4 binder to intergranular contacts of cathode materials agglomerates. The beneficial boron modification was demonstrated to be a result of Li3BO3 coating formation rather than doping, which also implies the plate-like primary particles growth due to reduction of (003) surface energy and their radial alignment within cathodes’ agglomerates, facilitating the Li+ diffusion across particles. Besides, the boron modification enables better reversibility of H2→H3 phase transition, which appears at the high voltages and detrimental for oxygen release and cathodes’ structure degradation. Finally, the developed in this work microwave-assisted hydrothermal synthesis for Ni-rich NMCs provides fast, facile and efficient way of cathodes’ powder production, which could be used as a space-filler to boost the tap density and energy density. Date: October 25, 2023 Time: 16:00-17:00 Speaker: Alina Pavlova, Skolkovo Institute of Science and Technology, MSc-2 in Materials Science and Engineering. Title: Single-crystal Ni-rich layered cathode materials for high energy density Li-ion batteries Abstract: The explosive growth of the electric vehicle market is driving strong growth in industry demand for next-generation lithium-ion batteries (LIBs). The positive electrode (cathode) of the battery is a limiting element and determines its electrochemical performance and cost. Nickel-rich layered transition metal oxides (LiNixCoyMnzO2 (x ≥ 0.6), Ni-rich NMCs) have been under intense investigation as high-energy density and low-cost positive electrode materials for LIBs. However, insufficient cyclic stability as well as low tap density hinder broad commercial application of commonly used polycrystalline Ni-rich NMCs. Within this Master’s thesis, high-performance Ni-rich NMC cathode materials (LiNi0.6Co0.2Mn0.2O2 and LiNi0.8Co0.1Mn0.1O2) in the form of single crystal particles with spherical and spherical-like shapes were obtained via molten-salt synthesis by adjusting μ(Li) in the melt through finding the right LiOH/K2SO4 ratio. The crystal structure of the obtained materials was scrutinized by powder X-ray diffraction (PXRD), the cation composition and homogeneity of transition metals distribution were investigated through energy-dispersive X-ray spectra in a STEM mode (STEM-EDX), morphology was investigated via scanning electron microscopy (SEM), the electrochemical performance was studied by galvanostatic cycling with potential limitation (GCPL) and electrochemical impedance spectroscopy (EIS). The obtained materials are well-crystallized with relatively low degree of anti-site disordering and homogeneous TM distribution. These newly developed materials demonstrate record tap density of 3.0 g/cm3 and high discharge capacity (200 mAh/g) and therefore, increased volumetric energy density (2680 WhL−1) compared to the polycrystalline counterparts, as well as outstanding cycling stability in both half-cell (91 % after 300 cycles at 1C rate) and full-cell (85 % after 300 cycles at 1C rate) configurations. The designed approach based on manipulation of single crystal faceting can be employed in rational design of a wide range of cathodes with better rate capability, higher volumetric energy density and cycling stability. Date: May 24, 2023 Time: 16:00-17:00 Speaker: Maksim Zakharkin, Research Scientist, Moscow State University. Title: Matching Electrochemical Properties and Phase Transformations in NASICON-type Electrode Materials for Na-ion batteries Abstract: NASICON-type Na3V2(PO4)3 cathode materials are considered as promising candidates for high-performance Na-ion batteries due to extremely long cyclic stability and an outstanding ability to operate at high (dis)charge rates. However, its cost-effectiveness can still be improved using transition metals cheaper than vanadium, which could also increase the energy density compared to that in Na3V2(PO4)3. The replacement of V with Mn and Cr in Na3V2(PO4)3 lowers the cost of the materials and enhances the operation voltage. Substitution of V by electrochemically inactive Mg and Sc allows studying vanadium redox processes without contributions from these metals. In order to link electrochemical features with the phase transformations in NASICON samples operando X-ray powder diffraction was carried out. The crystal structure changes on charge and discharge were studied as well as the electrode performance in narrow (2.5-3.8 V), wide (2.5-4.5 V) and extra wide (1.0-4.5 V) potential windows. The results indicate that in case of narrow voltage window the Na+ (de)intercalation reaction is reversible, however for the V-substituted compounds charging above 3.8 V increases energy density, but leads to the loss of reversibility and capacity fade. However, for some compounds an overdischarge below 2.5 V suppresses the capacity fade. The experimental results indicate the benefits of vanadium-substituted compounds and ability to outperform the unsubstituted materials in terms of rate-capability. Therefore they should be preferred for high-power applications. Date: May 17, 2023 Time: 16:00-17:00 Speaker: Svetlana Artiukova, Skolkovo Institute of Science and Technology, PhD-2 in Materials Science and Engineering. Title: Treating strongly electron-correlated energy materials with first-principles approaches Abstract: It is a known fact that conventional DFT LDA and GGA approaches fail to predict band gaps of strongly correlated materials. The existing more accurate and reliable approaches such as GW and hybrid functionals are much more computationally expensive and can’t be applied for large systems as well as in high-throughput screening. One of the possible ways to overcome this problem is using Hubbard U correction, which allows to compensate for the delocalization error by introducing an additional term in hamiltonian. For the new materials properties prediction it is necessary to calculate Hubbard correction from the first principles. Recently, a new pseudo-hybrid functional ACBN0 [1] was proposed by L. Agapito and co-authors, which provide a self-consistent way to calculate U using occupation matrix while usual steps DFT self-consistent procedure, which makes this method computationally comparable with DFT GGA/LDA. This work provides broader analysis of ACBN0 prediction capabilities for treating strongly correlated materials, such as transition metal oxides, with comparison of other methods that should correct DFT band gaps. Also, ACBN0 was implemented in FHI-aims code and preliminary tested. Since FHI-aims[2] is all-electron, full-potential code with numeric atom-centered orbitals as basis set, it becomes natural to define localized subspace through the atomic basis, also avoiding pseudopotentials that are necessary for plane-waves basis set codes (Quantum Espresso[1], OCTOPUS[3]). [1] Agapito, L. A., Curtarolo, S., & Nardelli, M. B. (2015). Reformulation of DFT+U as a pseudohybrid hubbard density functional for accelerated materials discovery. Physical Review X, 5(1), 011006. [2] Blum, V., Gehrke, R., Hanke, F., Havu, P., Havu, V., Ren, X., … & Scheffler, M. (2009). Ab initio molecular simulations with numeric atom-centered orbitals. Computer Physics Communications, 180(11), 2175-2196. [3] Tancogne-Dejean, N., Rubio, A. (2020). Parameter-free hybridlike functional based on an extended Hubbard model: DFT+U+V. Physical Review B, 102(15), 155117. Date: May 10, 2023 Time: 16:00-17:00 Speaker: Dmitry V. Pelegov 1,2 1 Institute of Natural Sciences and Mathematics, Ural Federal University, Ekaterinburg 2 Electromobility Institute, Moscow Institute of Physics and Technology Title: Raman Spectroscopy for Lithium Battery Materials: Current State and Outlook Abstract: The explosive growth of the electric vehicle market, which began in 2011, caused an equally explosive growth in the lithium battery industry. Today, in most developed countries of the world, these relatively young industries are on the lists of the most priority and governmentally supported. The cost of traction batteries today is more than 10% of the cost of an electric vehicle, and the standard warranty period is from 5 to 8 years. In this regard, the issue of quality control of lithium battery materials becomes extremely relevant, especially for countries where their industrial production is at an early stage of development. Cathode and anode materials are the main elements of lithium batteries and determine their consumer properties. This report is of an overview nature and introduces the history of the use of Raman spectroscopy to study the structure of cathode and anode materials, the current state of this area of research, and its main problems. The report also assesses the prospects for the use of Raman spectroscopy for industrial and laboratory control of lithium battery materials. Date: April 26, 2023 Time: 16:00-17:00 Place: Join ONLINE Speaker: Maria Makarova, Skolkovo Institute of Science and Technology, PhD-2 in Materials Science and Engineering. Title: Use of new highly soluble heterocyclic compounds in all-organic redox flow batteries Abstract: Among the developing energy storage technologies, redox flow batteries (RFBs) are considered prospective for large-scale stationary storage. In RFBs, separation of electrochemical cell and tanks with electrolytes allows to scale power and capacity of the battery independently. However, the most developed RFBs, which are based on vanadium-containing compounds, have several disadvantages including low energy density (< 25 Wh L 1) and output voltage (1.4 V). Also, widespread use of this technology is hindered due to unstable vanadium prices. To overcome these problems, RFBs based on organic active materials are being intensely explored. Organic materials are specifically promising due to their flexible design, improved solubility in organic solvents, and low cost, and moreover application of organic solvents allows expanding of the operational potential of the batteries up to 5 V. In this work, two novel redox-active organic molecules, based on benzoxadiazole and benzothiadiazole cores and bearing ethylene glycol substituents, are investigated in terms of their synthesis, electrochemical properties, and energy storage behavior as negative electrolytes in all-organic redox flow batteries. Date: April 19, 2023 Time: 16:00-17:00 Speaker: Denis Alikin, Head of the Functional Nanomaterials and Nanodevices Laboratory at UrFU. Title: Correlative scanning probe and confocal Raman microscopy for evaluation of Li-ion kinetics in LiMn2O4 cathodes during battery cycling Abstract: We will discuss a quantitative indirect method of electrochemical properties characterization, so-called electrochemical strain microscopy (ESM), which relies on the modulation of the ion concentration in the vicinity of scanning probe microscopy tip via electrical stimuli. Complementary correlative confocal Raman and scanning probe microscopy approach help to find a relation between the structural state and functional electrochemical response in individual micro-scale particles of a LiMn2O4 spinel in a commercial Li-battery cathode. The low-frequency ESM method was approved to give quantitative data on local Li-ion concentration and diffusion coefficients. The observed features of ESM signal distribution across the cathode are used for the interpretation of Li-ion intercalation kinetics during battery degradation. About the Speaker: Denis Alikin received his PhD in physics of condensed matter from Ural Federal University in 2012, specializing in scanning probe characterization of functional materials. Was a postdoctoral researcher at the University of Aveiro, Portugal (2019-2021) working on advanced battery characterization by scanning probe microscopy methods. At present is a Head of the Functional Nanomaterials and Nanodevices Laboratory at UrFU. Alikin’s research interests are in-depth research of electronic and ionic transport in the functional oxides and the development of quantitative scanning probe microscopy for characterization and fabrication of the nanosized functionalities. Date: February 15, 2023 Time: 16:00-17:00 Place: Join ONLINE Speaker: Natalia Katorova, N.D. Zelinsky Institute of Organic Chemistry of RAS, Skoltech alumni. Title: The effect of selected electrode-solution interactions on the potassium-ion battery electrochemical performance Abstract: Potassium-ion batteries (PIBs) exhibit poor electrochemical performance stemming from electrolyte decomposition during cycling due to the formation of unstable Solid Electrolyte Interphase (SEI) and Cathode Electrolyte Interphase (CEI) layers on surfaces of negative and positive electrodes respectively. Strategies to improve the stability of SEI/CEI layers over cycling for PIBs comprise solvent change, the enhanced salt concentration, and the utilization of electrolyte additives. Herein, all these approaches are explored. A decrease in free solvent molecule number with increasing electrolyte concentration in diglyme-based electrolytes is found, which results in a better aluminum current collector stability, formation of thinner solid electrolyte interphase (SEI) passivation layers, and further inhibition of solvent degradation redox processes occurring at the electrode surface upon cycling. Finally, electrochemical tests on K full cells consisting of the K1.44Mn[Fe(CN)6]0.90.4H2O cathode, a hard carbon (HC) anode, and an ether-based electrolyte show capacity retention of 86% over 300 cycles at a 0.6 C rate. The possible reasons of HC capacity loss are examined with a combination of in situ AFM and various ex-situ TEM techniques (HR-TEM and HAADF-STEM imaging, STEM-EELS and STEM-EDX spectroscopic mapping) targeting the electrode/electrolyte interphase formation process in carbonate-based electrolyte with and without vinylene carbonate (VC) as an additive. The studied HC consists of curved graphitic layers arranged into short packets and round cages, the latter acting as traps for K+ ions causing low Coulombic efficiency between cycling. Our comparative study of solid electrolyte interphase (SEI) formation in the carbonate-based electrolyte with and without VC additive revealed that in the pristine electrolyte SEI consists mostly of inorganic components whereas adding VC introduces a polymeric organic component to the SEI increasing its elasticity and stability against fracturing upon HC expansion/contraction during electrochemical cycling. Date: February 8, 2023 Time: 16:00-17:00 Place: Join ONLINE Speaker: Filipp Obrezkov, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Ultrafast charging polyphenylamine-based cathode material for high rate lithium, sodium and potassium batteries Abstract: We report the synthesis and investigation of a novel redox-active poly(N,N’-diphenyl-p-phenylenediamine) (PDPPD) polymer obtained via Buchwald-Hartwig C-N cross-coupling reaction. PDPPD has a high density of redox-active amine groups enabling the theoretical specific capacity of 209 mA h g-1, which is nearly twice higher compared to all other materials of this family reported so far. The obtained polymer was evaluated as a cathode material for dual-ion batteries and demonstrated promising operation voltages of 3.5-3.7 V and decent practical gravimetric capacities of 97, 94 and 63 mA h g-1 in lithium, sodium and potassium half-cells, respectively, while being tested at the moderate current density of 1C. A specific capacity of 84 mA h g-1 was obtained for the ultrafast lithium batteries operating at 100C (full charge and discharge takes 36 seconds only), which is, to the best of our knowledge, the highest battery capacity reported so far for such high current densities. The PDPPD//Li batteries also showed promising stability reflected in 67% capacity retention after 5000 cycles. Speaker: Roman Kapaev, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Transition metal coordination polymers for metal-ion batteries Abstract: Metal-organic polymers might be tuned to have high electrochemical capacity, high electron and ion conductivity and excellent cycling stability, which are necessary for the next generation of metal-ion batteries (MIBs) that are able to charge/discharge quickly over tens of thousands of cycles. In this report, synthesis and characterization of new classes of transition metal coordination polymers, which remain virtually unexplored as active materials for MIBs, are presented. In particular, metal-organic polymers derived from tetraaminobenzene, tetraaminobenzoquinone and dithiooxamide were studied. These compounds were shown to be promising as both ultrastable and ultrafast anode materials (>10 thousand cycles at >10 C) and cathode materials with high capacity and energy density (up to 350 mAh/g in 1.5-4.0 V vs. Li/Li+ range) in lithium- and sodium-ion batteries. Date: December 12, 2018 Speaker: Valeriy Okatenko, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Oxide materials with tetrahedrally coordinated d-metal for oxygen electrocatalysis Abstract: Reversible water decomposition is a promising system for energy storage, e.g. serving as a basis for regenerative alkaline fuel cells. At the same, wide implementation is strongly limited due to kinetic difficulties accompanying oxygen reduction (ORR, water formation) and oxygen evolution (OER, water decomposition) reactions. As the catalysts proven to be reasonably effective and stable are based on precious metals, moderately costed and still efficient catalysts are required. Bifunctional (effective for both OER and ORR) catalysts based on transition metals oxides have been investigated for some time now, but still no appropriate solution was found. Usually, oxides used in testing contain octahedrally-coordinated d-metal in their crystal structure. At the same time, materials with pure tetrahedral coordination of transition metals were not investigated so wide. Recently, lattice-oxygen mediated mechanism (LOM) was introduced by K. Stevenson’s group, which includes oxygen vacancies transformation during OER and ORR. That leads to the assumption on the necessity of oxygen non-stoichiometry in the bifunctional catalysts. The talk delivered will cover the investigation of tetrahedrally-coordinated d-metal oxide materials as bifunctional catalysts. In particular, YBaCo4O7+δ and CaBaCo4O7+δ are the point of focus, basing on the high oxygen non-stoichiometry index (up to 1.5 and 1.0, respectively, standing for full Co2+ to Co3+ oxidation) and high electronic conductivity (σ ~ 2,5 S/cm at 50°C). Speaker: Alexey Akmaev, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Hydrothermal synthesis of Na2FePO4F and interionic replacement of (PO4)3- to (BO3)3- Abstract: Nowadays metal-ion batteries are one of the most perspective systems among other rechargeable electrochemical ones. Metal-ion batteries use in the vast majority of equipment such as electric vehicles, power tools, stationary energy storage, etc. The most important component of metal-ion batteries is the cathode material, which determines the serious parameters of the battery, such as specific energy, specific power, reliability, lifetime and the cost of a unit of stored energy. The transition metal compounds containing the various polyanionic units like PO43, VO43-, SO42-, SiO44-, CO32-, BO33- are considered the most promising cathode materials for the next generation of metal-ion batteries due to the high redox potential caused by the inductive effect and good electrochemical and thermal stability. In this work polyanionic cathode material Na2FePO4F was synthesized by hydrothermal method. It shows a good electrochemical performance. It demonstrates more than 90% of specific capacity at 0.1 C and sufficiently stable work during the long cycling and the cycling rate increasing. There is a PO4 group which is tetrahedron and has a hanging oxygen atom. In this work we tried to fix this atom through triangle BO3 group by interionic replacement. Date: November 14, 2018 Speaker: Aleksandra Boldyreva, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Gamma ray induced degradation effects in triple cation perovskite solar cells Abstract: Solar cells based on complex lead halides with the perovskite structure have attracted particular attention of material scientists and engineers all over the world. Rapid improvement in terms of power conversion efficiencies, which exceeded 22% in combination with potentially low fabrication costs of perovskite solar cells might accomplish a revolution on the PV market. Perovskite solar cells can also be fabricated on ultrathin and lightweight substrates, which makes them particularly attractive for both terrestrial and space applications. Conventional solar cells based on silicon, gallium arsenide or A3B5 type absorbers are usually installed on the satellites. However, these materials rapidly degrade under severe radiation exposure in space. While high-energy particles can be blocked efficiently by the solar cell encapsulation layers, the degradation induced by gamma irradiation from random Sun flares can hardly be avoided. Therefore, development of novel PV materials and solar cell architectures capable of sustaining significant gamma irradiation represents a highly relevant task. In this paper, we will report an experimental evaluation of the gamma radiation tolerance of perovskite solar cells. The effects of the light absorber (triple cation MA(x)FA(y)Cs(z)PbBrnI3-n) formulation and the electron transport materials on the device stability will be discussed in detail. Finally, we will conclude on the potential of the perovskite photovoltaics with respect to the space applications. Speaker: Maxim Zakharkin, Skolkovo Institute of Science and Technology, Center for Electrochemical Energy Storage, Russia. Title: Enhancing Na+ Extraction Limit Through High Voltage Activation of the NASICON-type Na4MnV(PO4)3 Cathode Abstract: Great efforts of battery community were focused on improving performance of a cathode material for sodium-ion batteries Na3V2(PO4)3, however extraction from its structure of more than 2 Na+ ions per formula unit remains the main issue. The presentation will be devoted to a new Na4MnV(PO4)3, where substitution of a part of V3+ by Mn2+ significantly modifies electrochemical properties and reversibly enhances the extraction limit. Our fresh results show how extention of the voltage window changes the (de)intercalation mechanism, activates “locked” Na positions and raises new challenges.
Date: November 01, 2023
Time: 16:00-17:00
Place: TPOC-3, Nobel str., 3, Blue Building, CEDL (4th floor, Room 450)
Time: 16:00-17:00
Place: TPOC-3, Nobel str., 3, Blue Building, CEDL (4th floor, Room 450)