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Kolesnichenko, Igor V.

Publications and source records attributed to Kolesnichenko, Igor V..

7 records
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DOE OSTI2022

A pseudo-two-dimensional (P2D) model for FeS 2 conversion cathode batteries

Conversion cathode materials are gaining interest for secondary batteries due to their high theoretical energy and power density. However, practical application as a secondary battery material is currently limited by practical issues such as poor cyclability. To better understand these materials, we have, for this study, developed a pseudo-two-dimensional model for conversion cathodes. We apply this model to FeS 2 – a material that undergoes intercalation followed by conversion during discharge. The model is derived from the half-cell Doyle–Fuller–Newman model with additional loss terms added to reflect the converted shell resistance as the reaction progresses. We also account for polydisperse active material particles by incorporating a variable active surface area and effective particle radius. Using the model, we show that the leading loss mechanisms for FeS 2 are associated with solid-state diffusion and electrical transport limitations through the converted shell material. The polydisperse simulations are also compared to a monodisperse system, and we show that polydispersity has very little effect on the intercalation behavior yet leads to capacity loss during the conversion reaction. Finally, we provide the code as an open-source Python Battery Mathematical Modeling (PyBaMM) model that can be used to identify performance limitations for other conversion cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2022

Temperature-Dependent Reaction Pathways in FeS 2 : Reversibility and the Electrochemical Formation of Fe 3 S 4

The present study has used a variety of characterization techniques to determine the products and reaction pathways involved in the rechargeable Li–FeS 2 system. We revisit both the initial lithiation and subsequent cycling of FeS 2 employing an ionic liquid electrolyte to investigate the intermediate and final charge products formed under varying thermal conditions (room temperature to 100 °C). The detection of Li 2 S and hexagonal FeS as the intermediate phases in the initial lithiation and the electrochemical formation of greigite, Fe 3 S 4 , as a charge product in the rechargeable reaction differ significantly from previous reports. The conditions for Fe 3 S 4 formation are shown to be dependent on both the temperature (~60 °C) and the availability of sulfur to drive a FeS to Fe 3 S 4 transformation. Upon further cycling, Fe 3 S 4 transforms to a lower sulfur content iron sulfide phase, a process which coincides with the loss of sulfur based on the new reaction pathways established in this work. The connection between sulfur loss, capacity fade, and charge product composition highlights the critical need to retain sulfur in the active material upon cycling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Understanding the Electrochemical Performance of FeS 2 Conversion Cathodes

Conversion cathodes represent a viable route to improve rechargeable Li + battery energy densities, but their poor electrochemical stability and power density have impeded their practical implementation. Here, we explore the impact cell fabrication, electrolyte interaction, and current density have on the electrochemical performance of FeS 2 /Li cells by deconvoluting the contributions of the various conversion and intercalation reactions to the overall capacity. By varying the slurry composition and applied pressure, we determine that the capacity loss is primarily due to the large volume changes during (de)lithiation, leading to a degradation of the conductive matrix. Through the application of an external pressure, the loss is minimized by maintaining the conductive matrix. Further, we determine that polysulfide loss can be minimized by increasing the current density (>C/10), thus reducing the sulfur formation period. Analysis of the kinetics determines that the conversion reactions are rate-limiting, specifically the formation of metallic iron at rates above C/8. While focused on FeS 2 , our findings on the influence of pressure, electrolyte interaction, and kinetics are broadly applicable to other conversion cathode systems.

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DOE OSTI2022

Morphology and Dynamics in Hydroxide-Conducting Polysulfones

In alkaline zinc–manganese dioxide batteries, there is a need for selective polymeric separators that have good hydroxide ion conductivity but that prevent the transport of zincate (Zn(OH) 4 ) 2- . Here we investigate the nanoscale structure and hydroxide transport in two cationic polysulfones that are promising for these separators. We present the synthesis and characterization for a tetraethylammonium-functionalized polysulfone (TEA-PSU) and compare it to our previous work on an N-butylimidazolium-functionalized polysulfone (NBI-PSU). We perform atomistic molecular dynamics (MD) simulations of both polymers at experimentally relevant water contents. The MD simulations show that both polymers develop well phase separated nanoscale water domains that percolate through the polymer. Calculation of the total scattering intensity from the MD simulations reveal weak or nonexistent ionomer peaks at low wave vectors. The lack of an ionomer peak is due to a loss of contrast in the scattering. The small water domains in both polymers, with median diameters on the order of 0.5–0.7 nm, lead to hydroxide and water diffusion constants that are 1–2 orders of magnitude smaller than their values in bulk water. This confinement lowers the conductivity but also may explain the strong exclusion of zincate from the PSU membranes seen experimentally.

25 ENERGY STORAGE↗
DOE OSTI2021

Ultradoping Boron on Si(100) via Solvothermal Chemistry

Ultradoping introduces unprecedented dopant levels into Si, which transforms its electronic behavior and enables its use as a next-generation electronic material. Commercialization of ultradoping is currently limited by gas-phase ultra-high vacuum requirements. Solvothermal chemistry is amenable to scale-up. However, an integral part of ultradoping is a direct chemical bond between dopants and Si, and solvothermal dopant-Si surface reactions are not well-developed. This work provides the first quantified demonstration of achieving ultradoping concentrations of boron (~1e14 cm 2 ) by using a solvothermal process. Surface characterizations indicate the catalyst cross-reacted, which led to multiple surface products and caused ambiguity in experimental confirmation of direct surface attachment. Density functional theory computations elucidate that the reaction results in direct B-Si surface bonds. Finally, this proof-of-principle work lays groundwork for emerging solvothermal ultradoping processes.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Zincate-Blocking-Functionalized Polysulfone Separators for Secondary Zn–MnO 2 Batteries

Alkaline zinc–manganese dioxide (Zn–MnO 2 ) batteries are well suited for grid storage applications because of their inherently safe, aqueous electrolyte and established materials supply chain, resulting in low production costs. With recent advances in the development of Cu/Bi-stabilized birnessite cathodes capable of the full 2-electron capacity equivalent of MnO 2 (617 mA h/g), there is a need for selective separators that prevent zincate (Zn(OH) 4 ) 2– transport from the anode to the cathode during cycling, as this electrode system fails in the presence of dissolved zinc. In this work, we present the synthesis of N-butylimidazolium-functionalized polysulfone (NBI-PSU)-based separators and evaluate their ability to selectively transport hydroxide over zincate. We then examine their impact on the cycling of high depth of discharge Zn/(Cu/Bi–MnO 2 ) batteries when inserted in between the cathode and anode. Initially, we establish our membranes’ selectivity by performing zincate and hydroxide diffusion tests, showing a marked improvement in zincate-blocking (D Zn (cm 2 /min): 0.17 ± 0.04 × 10 –6 for 50-PSU, our most selective separator vs 2.0 ± 0.8 × 10 –6 for Cellophane 350P00 and 5.7 ± 0.8 × 10 –6 for Celgard 3501), while maintaining similar crossover rates for hydroxide (D OH (cm 2 /min): 9.4 ± 0.1 × 10 –6 for 50-PSU vs 17 ± 0.5 × 10 –6 for Cellophane 350P00 and 6.7 ± 0.6 × 10 –6 for Celgard 3501). We then implement our membranes into cells and observe an improvement in cycle life over control cells containing only the commercial separators (cell lifetime extended from 21 to 79 cycles).

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