Marco Olguin
United States Army Research Laboratory
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Featured researches published by Marco Olguin.
Science | 2015
Liumin Suo; Oleg Borodin; Tao Gao; Marco Olguin; Janet Ho; Xiulin Fan; Chao Luo; Chunsheng Wang; Kang Xu
A concentrated effort for battery safety Aqueous electrolytes are limited to run below 1.23 V to avoid degradation. Suo et al. smash through this limit with an aqueous salt solution containing lithium (Li) bis(trifluoromethane sulfonyl)imide to create an electrolyte that has an electrochemical window of 3 V (see the Perspective by Smith and Dunn). They used extremely high-concentration solutions, which suppressed hydrogen evolution and electrode oxidation. At these concentrations, the Li solvation shell changes because there simply is not enough water to neutralize the Li+ charge. Thus, flammable organic electrolytes could potentially be replaced with a safer aqueous alternative. Science, this issue p. 938; see also p. 918 The electrochemical stability window of an aqueous electrolyte is expanded to 3 volts. [Also see Perspective by Smith and Dunn] Lithium-ion batteries raise safety, environmental, and cost concerns, which mostly arise from their nonaqueous electrolytes. The use of aqueous alternatives is limited by their narrow electrochemical stability window (1.23 volts), which sets an intrinsic limit on the practical voltage and energy output. We report a highly concentrated aqueous electrolyte whose window was expanded to ~3.0 volts with the formation of an electrode-electrolyte interphase. A full lithium-ion battery of 2.3 volts using such an aqueous electrolyte was demonstrated to cycle up to 1000 times, with nearly 100% coulombic efficiency at both low (0.15 C) and high (4.5 C) discharge and charge rates.
Nanotechnology | 2015
Oleg Borodin; Marco Olguin; Carrie Spear; Kenneth W. Leiter; Jaroslaw Knap
High throughput screening of solvents and additives with potential applications in lithium batteries is reported. The initial test set is limited to carbonate and phosphate-based compounds and focused on their electrochemical properties. Solvent stability towards first and second reduction and oxidation is reported from density functional theory (DFT) calculations performed on isolated solvents surrounded by implicit solvent. The reorganization energy is estimated from the difference between vertical and adiabatic redox energies and found to be especially important for the accurate prediction of reduction stability. A majority of tested compounds had the second reduction potential higher than the first reduction potential indicating that the second reduction reaction might play an important role in the passivation layer formation. Similarly, the second oxidation potential was smaller for a significant subset of tested molecules than the first oxidation potential. A number of potential sources of errors introduced during screening of the electrolyte electrochemical properties were examined. The formation of lithium fluoride during reduction of semifluorinated solvents such as fluoroethylene carbonate and the H-transfer during oxidation of solvents were found to shift the electrochemical potential by 1.5-2 V and could shrink the electrochemical stability window by as much as 3.5 V when such reactions are included in the screening procedure. The initial oxidation reaction of ethylene carbonate and dimethyl carbonate at the surface of the completely de-lithiated LiNi0.5Mn1.5O4 high voltage spinel cathode was examined using DFT. Depending on the molecular orientation at the cathode surface, a carbonate molecule either exhibited deprotonation or was found bound to the transition metal via its carbonyl oxygen.
ACS Nano | 2017
Oleg Borodin; Liumin Suo; Mallory Gobet; Xiaoming Ren; Fei Wang; Antonio Faraone; Jing Peng; Marco Olguin; Marshall A. Schroeder; Michael S. Ding; Eric Gobrogge; Arthur v. Cresce; Stephen Munoz; Joseph A. Dura; Steve Greenbaum; Chunsheng Wang; Kang Xu
Using molecular dynamics simulations, small-angle neutron scattering, and a variety of spectroscopic techniques, we evaluated the ion solvation and transport behaviors in aqueous electrolytes containing bis(trifluoromethanesulfonyl)imide. We discovered that, at high salt concentrations (from 10 to 21 mol/kg), a disproportion of cation solvation occurs, leading to a liquid structure of heterogeneous domains with a characteristic length scale of 1 to 2 nm. This unusual nano-heterogeneity effectively decouples cations from the Coulombic traps of anions and provides a 3D percolating lithium-water network, via which 40% of the lithium cations are liberated for fast ion transport even in concentration ranges traditionally considered too viscous. Due to such percolation networks, superconcentrated aqueous electrolytes are characterized by a high lithium-transference number (0.73), which is key to supporting an assortment of battery chemistries at high rate. The in-depth understanding of this transport mechanism establishes guiding principles to the tailored design of future superconcentrated electrolyte systems.
Journal of Materials Chemistry | 2017
Jenel Vatamanu; Oleg Borodin; Marco Olguin; Gleb Yushin; Dmitry Bedrov
Supercapacitors or electrical double layer (EDL) capacitors store charge via rearrangement of ions in electrolytes and their adsorption on electrode surfaces. They are actively researched for multiple applications requiring longer cycling life, broader operational temperature ranges, and higher power density compared to batteries. Recent developments in nanostructured carbon-based electrodes with a high specific surface area have demonstrated the potential to significantly increase the energy density of supercapacitors. Molecular modeling of electrolytes near charged electrode surfaces has provided key insights into the fundamental aspects of charge storage at the nanoscale, including an understanding of the mechanisms of ion adsorption and dynamics at flat surfaces and inside nanopores, and the influence of curvature, roughness, and electronic structure of electrode surfaces. Here we review these molecular modeling findings for EDL capacitors, dual ion batteries and pseudo-capacitors together with available experimental observations and put this analysis into the perspective of future developments in this field. Current research trends and future directions are discussed.
Energy and Environmental Science | 2018
Feixiang Wu; Travis P. Pollard; Enbo Zhao; Yiran Xiao; Marco Olguin; Oleg Borodin; Gleb Yushin
Lithium sulfide (Li2S) cathodes have been viewed as very promising candidates for next-generation lightweight Li and Li-ion batteries. Prior work on the deposition of carbon shells around Li2S particles showed reduced dissolution of polysulfides and improved cathode stability. However, due to the substantial volume changes during cycling and the low chemical binding energy between carbon and sulfides, defects almost inevitably forming in the carbon shell during battery operation commonly lead to premature cell failure. In this study, we show that conformal coatings of layered LiTiO2 may offer better protection against polysulfide dissolution and the shuttle effects. Density functional theory (DFT) calculations revealed that LiTiO2 exhibits a strong affinity for sulfur species (Li2Sx) and, most importantly, induces a rapid conversion of longer (highly soluble) polysulfides to short polysulfides, which exhibit minimum solubility in electrolytes. Quite remarkably, even the mere presence of the electronically conductive layered oxides (LiMO2, M = metal) such as LiTiO2 in the cathodes (e.g., as a component of the mix with Li2S) enhanced the cell rate and cycling stability dramatically. Advanced material characterization in combination with quantum chemistry calculations provided unique insights into the mechanisms of the incredible performance boost, such as interactions between Li2Sx and the LiTiO2 surface, leading to breakage of S–S bonds.
Physical Chemistry Chemical Physics | 2016
Oleg Borodin; Marco Olguin; Panchapakesan Ganesh; Paul R. C. Kent; Joshua L. Allen; Wesley A. Henderson
Electrochimica Acta | 2016
Samuel A. Delp; Oleg Borodin; Marco Olguin; Claire G. Eisner; Joshua L. Allen; T. Richard Jow
Journal of Physical Chemistry C | 2016
Joshua P. McClure; Oleg Borodin; Marco Olguin; Deryn Chu; Peter S. Fedkiw
228th ECS Meeting (October 11-15, 2015) | 2015
Oleg Borodin; Marco Olguin; Carrie Spear; Kenneth W. Leiter; Jaroslaw Knap; Gleb Yushin; Adam Childs; Kang Xu
Materials Today | 2018
Judith Alvarado; Marshall A. Schroeder; Minghao Zhang; Oleg Borodin; Eric Gobrogge; Marco Olguin; Michael S. Ding; Mallory Gobet; Steve Greenbaum; Ying Shirley Meng; Kang Xu