Papers by Natasha Chernova
Operando XAS to Illustrate the Importance of Electronic Conductivity in Vanadyl Phosphate Systems
Journal of The Electrochemical Society, 2021
Multi-electron cathodes are an exciting class of energy storage materials that can intercalate mo... more Multi-electron cathodes are an exciting class of energy storage materials that can intercalate more than one alkali-ion per transition metal. One such case, nano-sized ε-VOPO4 can intercalate two Li-ions to obtain the theoretical capacity of 305 mAh g−1, despite its inherently poor ionic and electronic conductivity. While carbon additives can compensate for cathode material’s poor conductivity, the type of carbon additive can play a key role in achieving full theoretical capacity of ε-VOPO4. Here, we explore the electrochemical behavior of two sourced carbons while systematically tracking V valence through operando X-ray absorption spectroscopy. The degree of V redox largely depends on the carbon additive’s electrical conductivity and surface coverage, with graphene enabling full 2 li-ion (de)intercalation whereas the use of acetylene black leads to trapped Li-ion. In both cases however, side reactions are promoted when the limits of facile Li (de)intercalation are reached resulting...
(Invited) Resolution of the 1st Capacity Loss of Layered Oxide Cathodes
ECS Meeting Abstracts, 2020
Layered transition-metal oxides are the dominant cathodes in present commercial Li-ion batteries,... more Layered transition-metal oxides are the dominant cathodes in present commercial Li-ion batteries, and are also the leading choice for electric vehicles, because much higher capacity can be obtained with high Ni content, which has the potential to achieve the cell-level energy density above 300 Wh/kg for NMC 811. However, the large 1st capacity loss (~ 15% of the charging capacity) limits the achievable capacity for this attractive cathode materials. If this capacity loss can be eliminated, the energy density could 400 Wh/kg. Our initial studies have found that ~ 80% of the 1st capacity loss of NMC 811 can be attributed to slow lithium diffusion at high lithium concentrations; this may be due to the divacancy diffusion mechanism for Li ions in the layers of the structure. The dramatic drop of the Li divacancy concentration can cause the sharp decrease on Li ion diffusion. However, the layered oxide cathode, LiCoO2, has a much smaller 1st capacity loss, 5 mAh/g vs. 27 mAh/g for 811 fo...
(Invited) Synthesis and Electrochemical Performance of Nb Coated/Substituted Nickel-Rich Layered Oxide Cathodes in Lithium Ion Batteries
ECS Meeting Abstracts, 2020
Layered metal oxides have been considered the most important cathode materials in Li-ion batterie... more Layered metal oxides have been considered the most important cathode materials in Li-ion batteries. Further, nickel rich LiNixCoyMn1-x-yO2 (x ≥ 0.8) cathodes are very attractive in automotive industry due to their high discharge capacities. However, the high nickel content creates a number of challenges, including high surface reactivity and structural instability. Through a wet chemistry method, Nb coated and substituted NMC 811 was prepared in a single step treatment. The coating layer and penetration of Nb can be controlled by sintering temperature. As a result, the 1st capacity loss, discharge capacity, rate performance and cycling stability were significantly improved. In addition, we found the Nb coating layer can increase the discharge capacity and Nb penetrated into NMC 811 can stabilize the structure. Acknowledgement: This work was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy...
The Role of Niobium Substitution in Lithium Vanadyl Phosphate for Lithium-Ion Batteries
ECS Meeting Abstracts, 2020
Li-ion intercalation compound enlisting multi-electron redox is a promising strategy to maximize ... more Li-ion intercalation compound enlisting multi-electron redox is a promising strategy to maximize the storage capacity of LIBs. Lithium vanadyl phosphate, LiVOPO4, is one such material that can intercalate up to two Li+ ions per vanadium ion through the change in vanadium valence from V5+ to V3+, which translates to a theoretical capacity of 305 mAh/g and an energy density above 900 Wh/kg. However, Li-ion intercalation in the high voltage region (V5+/V4+) is kinetically limited by the sluggish Li-ion diffusion, and thus impedes the use of LiVOPO4 in practical applications. The goal of this work is to explore experimentally if niobium substitution can enhance the electrochemical performance of LiVOPO4. Lab X-ray diffraction, electron microscopy-energy-dispersive X-ray analysis, and inductively coupled plasma atomic emission spectroscopy indicate niobium is substituted into the LiVOPO4 crystal structure. A qualitative difference in the charge-discharge voltage profile is observed betwe...
(Invited) High Rate Cycling in ε-VOPO4 with Niobium Substitution for Lithium-Ion Batteries
ECS Meeting Abstracts, 2020
In order to push the energy density of current commercialized lithium-ion batteries, a second lit... more In order to push the energy density of current commercialized lithium-ion batteries, a second lithium must be incorporated into the cathode host without causing any structural damage during intercalation. ε-VOPO4 is a promising high energy density cathode material for lithium-ion batteries due to its ability to fully reversibly intercalate two Li+ from the two redox transitions of V3+/V4+ and V4+/V5+. As a result, ε-VOPO4 displays a high discharge capacity of 305 mAh/g at C/50 (C = 2 Li) for over 50 cycles. However, this vanadyl phosphate material experiences poor Li+ kinetics which impedes its high rate capability at the high voltage plateau. In this work, we determine if niobium substitution can improve the electrochemistry of ε-VOPO4. Through X-ray diffraction and scanning electron microscopy, we investigate the incorporation of niobium in the structure and the effect on morphology. The analysis of substitution on the electrochemical performance will also be discussed alongside w...
Submitted for the MAR07 Meeting of The American Physical Society Magnetic properties of vanadium ... more Submitted for the MAR07 Meeting of The American Physical Society Magnetic properties of vanadium oxide nanorods, nanotubes and nanourchins.1 NATASHA CHERNOVA, CHRIS JACOBS, MEGAN ROPPOLO, KRISTIN BUTTERWORTH, CHUNMEI BAN, M. STANLEY WHITTINGHAM, Institute for Materials Research, SUNY Binghamton — Vanadium oxide nanotubes (VONTs) were prepared by hydrothermal method and ion exchanged with BuLi. Vanadium oxide nanorods were synthesized by hydrothermal treatment of electrospun precursors. The compounds were characterized by x-ray diffraction, TGA, TEM, FTIR and magnetic susceptibility techniques. Magnetic properties of VONTs are found to be similar to that reported earlier [1]. Upon ion exchange with BuLi the amount of isolated V4+ is preserved, but the spin-gap behavior becomes less pronounced. No hysteresis of magnetization is found as opposed to earlier report [1]. Vanadium oxide nanourchins have similar structure with VONTs; however, their magnetic properties are different. Vanadiu...
Please note that technical editing may introduce minor changes to the text and/or graphics, which... more Please note that technical editing may introduce minor changes to the text and/or graphics, which may alter content. The journal’s standard Terms & Conditions and the ethical guidelines, outlined in our author and reviewer resource centre, still apply. In no event shall the Royal Society of Chemistry be held responsible for any errors or omissions in this Accepted Manuscript or any consequences arising from the use of any information it contains. Accepted Manuscript
Enhanced High-Rate Performance of Nanosized Single Crystal ε-VOPO4 with Niobium Substitution for Lithium-Ion Batteries
Journal of The Electrochemical Society, 2021
Recent Trends in Intercalation Chemistry Cathodes and Anodes for Lithium Batteries
ECS Meeting Abstracts, 2006
not Available.
Journal of Materials Chemistry A, 2020
Solid-state NMR combined with DFT calculations are used to characterise metastable phases formed ... more Solid-state NMR combined with DFT calculations are used to characterise metastable phases formed during (electro)chemical lithiation of β-(Li)VOPO4.
Enhanced Electrochemical Performance of Fe-Sn Alloy with Cu Additive As Anode in Lithium-Ion Batteries
ECS Meeting Abstracts, 2017
Tin based alloys have attracted much attention as one of the promising anode materials because of... more Tin based alloys have attracted much attention as one of the promising anode materials because of their higher gravimetric/volumetric capacity and safer thermodynamic potential for next generation lithium-ion batteries. Ultrasmall Fe-Sn alloy with Cu additive (Fe-Sn-(Cu)) was synthesized using Sn nanoparticles as template by modified polyol method. Compared with Fe-Sn alloy, the cycling performance and rate capability were largely enhanced when Fe-Sn-(Cu) alloy was used as anode with the average loading weight of 1.5 mg/cm2. It could deliver 465 mAh/g after 200 cyclesat the C/2 rate, corresponding to an average capacity loss of only 0.08% per cycle. The calculated volumetric capacity was more than 1.5 times of commercial carbon. It also has exceptional rate capability, delivering 91.9%, 82.6%, 74.4%, 63.5% of the 0.1C capacity (557 mAh/g) at 0.2C, 0.5C, 1C and 2C, respectively. Fe-Sn-(Cu) alloy with higher capacity and enhanced cycling performance may become a potential candidate as...
ACS Applied Materials & Interfaces, 2019
Journal of Materials Chemistry A, 2018
Ball-milling-induced disorder and defects impede multi-electron redox in ε-LiVOPO4 and trigger si... more Ball-milling-induced disorder and defects impede multi-electron redox in ε-LiVOPO4 and trigger side reactions.
Rational synthesis and electrochemical performance of LiVOPO4 polymorphs
Journal of Materials Chemistry A, 2019
A thorough study on the stability of LiVOPO4 polymorphs to determine which is the most promising ... more A thorough study on the stability of LiVOPO4 polymorphs to determine which is the most promising for Li-ion batteries.
Journal of Materials Chemistry A, 2018
Anisotropic disorder along the c-axis results from static disorder.
Journal of Materials Science, 2016
The volumetric energy density of today's lithium-ion batteries is limited mostly by the graphitic... more The volumetric energy density of today's lithium-ion batteries is limited mostly by the graphitic carbon anode. Silicon is a promising replacement but its excessive volume expansion on lithiation limits its long-term cyclability performance. A nano-sized aluminium containing silicon, leached in acid, with a porous structure is shown to maintain its capacity higher than pure bulk silicon or nano-sized silicon by over 700 mAh/g. The capacity of leached silicon is maintained at 1400 mAh/g for more than 60 cycles. X-ray diffraction, scanning electron microscopy, transmission electron microscopy and nuclear magnetic resonance spectroscopy have been used to correlate the electrochemical performance with the materials' morphology and composition.
STEM-EELS valence mapping and charge relaxation in LiFePO4 cathode
European Microscopy Congress 2016: Proceedings, 2016
Synthesis and Characterization of a New Layered Ethylene-Diammonium Manganese(II) Phosphate, (C2N2H10)Mn2 (PO4)2×2H2O
ChemInform, Mar 16, 2004
Can Vanadium Be Substituted into LiFePO[subscript 4]?
Chem Mater, 2011
Advanced Science, 2016
This is an open access article under the terms of the Creative Commons Attribution License, which... more This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Uploads
Papers by Natasha Chernova