Enhanced Ion Transport in an Ether Aided Super Concentrated Ionic Liquid Electrolyte for Long-Life Practical Lithium Metal Battery Applications

We explore a novel ether aided superconcentrated ionic liquid electrolyte; a combination of ionic liquid, <i>N</i>-propyl-<i>N</i>-methylpyrrolidinium bis(fluorosulfonyl)imide (C<sub>3</sub>mpyrFSI) and ether solvent, <i>1,2</i> dimethoxy ethane (DME) with 3.2 mol/kg LiFSI salt, which offers an alternative ion-transport mechanism and improves the overall fluidity of the electrolyte. The molecular dynamics (MD) study reveals that the coordination environment of lithium in the ether aided ionic liquid system offers a coexistence of both the ether DME and FSI anion simultaneously and the absence of ‘free’, uncoordinated DME solvent. These structures lead to very fast kinetics and improved current density for lithium deposition-dissolution processes. Hence the electrolyte is used in a lithium metal battery against a high mass loading (~12 mg/cm<sup>2</sup>) LFP cathode which was cycled at a relatively high current rate of 1mA/cm<sup>2</sup> for 350 cycles without capacity fading and offered an overall coulombic efficiency of >99.8 %. Additionally, the rate performance demonstrated that this electrolyte is capable of passing current density as high as 7mA/cm<sup>2</sup> without any electrolytic decomposition and offers a superior capacity retention. We have also demonstrated an ‘anode free’ LFP-Cu cell which was cycled over 50 cycles and achieved an average coulombic efficiency of 98.74%. The coordination chemistry and (electro)chemical understanding as well as the excellent cycling stability collectively leads toward a breakthrough in realizing the practical applicability of this ether aided ionic liquid electrolytes in lithium metal battery applications, while delivering high energy density in a prototype cell.

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Enhanced ion transport in an ether aided super concentrated ionic liquid electrolyte for long-life practical lithium metal battery applications

Journal of Materials Chemistry A ◽

10.1039/d0ta06344d ◽

2020 ◽

Vol 8 (36) ◽

pp. 18826-18839 ◽

Cited By ~ 2

Author(s):

Urbi Pal ◽

Fangfang Chen ◽

Derick Gyabang ◽

Thushan Pathirana ◽

Binayak Roy ◽

...

Keyword(s):

Ionic Liquid ◽

Ion Transport ◽

Transport Mechanism ◽

Liquid Electrolyte ◽

Lithium Metal ◽

Ionic Liquid Electrolyte ◽

Long Life ◽

Lithium Metal Battery

We explore a superconcentrated electrolyte comprising N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide, 1,2 dimethoxyethane and 3.2 mol kg−1 LiFSI. It offers an alternative ion-transport mechanism, improved fluidity and ultra-stable Li metal battery performance.

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A novel phosphonium ionic liquid electrolyte enabling high-voltage and high-energy positive electrode materials in lithium-metal batteries

Energy Storage Materials ◽

10.1016/j.ensm.2021.08.030 ◽

2021 ◽

Author(s):

Fanglin Wu ◽

Annika Regitta Schür ◽

Guk-Tae Kim ◽

Xu Dong ◽

Matthias Kuenzel ◽

...

Keyword(s):

Ionic Liquid ◽

High Voltage ◽

Electrode Materials ◽

High Energy ◽

Liquid Electrolyte ◽

Positive Electrode ◽

Lithium Metal ◽

Ionic Liquid Electrolyte ◽

Lithium Metal Batteries ◽

Phosphonium Ionic Liquid

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Improving Cycle Life Through Fast Formation Using a Super-Concentrated Phosphonium Based Ionic Liquid Electrolyte for Anode-Free and Lithium Metal Batteries

10.26434/chemrxiv.14702748 ◽

2021 ◽

Author(s):

Thushan Pathirana ◽

Dmitrii Rakov ◽

Fangfang Chen ◽

Maria Forsyth ◽

Robert Kerr ◽

...

Keyword(s):

Ionic Liquid ◽

Energy Density ◽

Electrochemical Impedance ◽

Cell Formation ◽

Lithium Ion ◽

High Energy ◽

Liquid Electrolyte ◽

High Energy Density ◽

Lithium Metal ◽

Ionic Liquid Electrolyte

<p>ABSTRACT </p><p>Cell formation of lithium-ion cells impacts the evolution of the solid electrolyte interphase (SEI) and the cell cycle stability. Lithium metal anodes are an important step in the development of high energy density batteries owing to the high theoretical specific capacity of lithium metal. However, most lithium metal battery research has used a conventional lithium-ion formation protocol; this is time consuming, costly and does not account for the different properties of the lithium metal electrode. Here, we have used a recently reported promising phosphonium bis(fluorosulfonyl)imide ionic liquid electrolyte coupled with an NMC622 high areal capacity cathode (>3.5 mAh/cm2) to investigate the effect of cell formation rates. A faster formation protocol comprised of a pulsed 1.25C current decreased the formation time by 56 % and gave a 38 % greater capacity retention after 50 cycles when compared to formation at C/20. Electrochemical impedance spectroscopy measurements showed that the fast formation gave rise to a lower-resistance SEI. Column-like lithium deposits with reduced porous lithium domains between the particles were observed using scanning electron microscope imaging. To underline the excellent performance of these high energy-density cells, a 56 % greater stack specific energy was achieved compared to the analogous graphite-based lithium-ion cell chemistries. </p>

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Paving the Way Toward Highly Efficient High-Energy Potassium-Ion Batteries with Ionic-Liquid Electrolytes

10.26434/chemrxiv.11988975 ◽

2020 ◽

Author(s):

Michele Fiore ◽

Kevin Hurlbutt ◽

Samuel Wheeler ◽

Isaac Capone ◽

Jack Fawdon ◽

...

Keyword(s):

Ionic Liquid ◽

Coulombic Efficiency ◽

Lithium Ion ◽

High Energy ◽

Liquid Electrolyte ◽

Potassium Ion ◽

Graphite Anode ◽

Ionic Liquid Electrolyte ◽

Prussian Blue Analog ◽

Operating Potential

<div><div><div><p>Potassium-ion batteries (KIB) are a promising complementary technology to lithium-ion batteries because of the comparative abundance and affordability of potassium. Currently, the most promising KIB chemistry consists of a potassium manganese hexacyanoferrate (KMF) cathode, a Prussian blue analog, and a graphite anode (723Whl−1 and 359Whkg−1 at 3.6V). No electrolyte has yet been formulated that is concurrently stable at the high operating potential of KMF (4.02V vs K+/K) and compatible with K+ intercalation into graphite, currently the most critical hurdle to adoption. Here we combine a KMF cathode and a graphite anode with a KFSI in Pyr1,3FSI ionic liquid electrolyte for the first time and show unprecedented performance. We use high-throughput techniques to optimize the KMF morphology for operation in this electrolyte system, achieving 119 mA h g−1 at 4 V vs K+/K and a coulombic efficiency >99.3%. In the same ionic liquid electrolyte graphite shows excellent electrochemical performance and we demonstrate reversible cycling by operando XRD. These results are a significant and essential step forward towards viable potassium-ion batteries.</p></div></div></div>

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Lithium Metal Battery Using LiFe0.5Mn0.5PO4 Olivine Cathode and Pyrrolidinium-Based Ionic Liquid Electrolyte

ACS Omega ◽

10.1021/acsomega.8b01328 ◽

2018 ◽

Vol 3 (8) ◽

pp. 8583-8588 ◽

Cited By ~ 5

Author(s):

Daniele Di Lecce ◽

Jusef Hassoun

Keyword(s):

Ionic Liquid ◽

Liquid Electrolyte ◽

Lithium Metal ◽

Ionic Liquid Electrolyte ◽

Lithium Metal Battery

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Improving Cycle Life Through Fast Formation Using a Super-Concentrated Phosphonium Based Ionic Liquid Electrolyte for Anode-Free and Lithium Metal Batteries

10.26434/chemrxiv.14702748.v1 ◽

2021 ◽

Author(s):

Thushan Pathirana ◽

Dmitrii Rakov ◽

Fangfang Chen ◽

Maria Forsyth ◽

Robert Kerr ◽

...

Keyword(s):

Ionic Liquid ◽

Energy Density ◽

Electrochemical Impedance ◽

Cell Formation ◽

Lithium Ion ◽

High Energy ◽

Liquid Electrolyte ◽

High Energy Density ◽

Lithium Metal ◽

Ionic Liquid Electrolyte

<p>ABSTRACT </p><p>Cell formation of lithium-ion cells impacts the evolution of the solid electrolyte interphase (SEI) and the cell cycle stability. Lithium metal anodes are an important step in the development of high energy density batteries owing to the high theoretical specific capacity of lithium metal. However, most lithium metal battery research has used a conventional lithium-ion formation protocol; this is time consuming, costly and does not account for the different properties of the lithium metal electrode. Here, we have used a recently reported promising phosphonium bis(fluorosulfonyl)imide ionic liquid electrolyte coupled with an NMC622 high areal capacity cathode (>3.5 mAh/cm2) to investigate the effect of cell formation rates. A faster formation protocol comprised of a pulsed 1.25C current decreased the formation time by 56 % and gave a 38 % greater capacity retention after 50 cycles when compared to formation at C/20. Electrochemical impedance spectroscopy measurements showed that the fast formation gave rise to a lower-resistance SEI. Column-like lithium deposits with reduced porous lithium domains between the particles were observed using scanning electron microscope imaging. To underline the excellent performance of these high energy-density cells, a 56 % greater stack specific energy was achieved compared to the analogous graphite-based lithium-ion cell chemistries. </p>

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Paving the Way Toward Highly Efficient High-Energy Potassium-Ion Batteries with Ionic-Liquid Electrolytes

10.26434/chemrxiv.11988975.v1 ◽

2020 ◽

Author(s):

Michele Fiore ◽

Kevin Hurlbutt ◽

Samuel Wheeler ◽

Isaac Capone ◽

Jack Fawdon ◽

...

Keyword(s):

Ionic Liquid ◽

Coulombic Efficiency ◽

Lithium Ion ◽

High Energy ◽

Liquid Electrolyte ◽

Potassium Ion ◽

Graphite Anode ◽

Ionic Liquid Electrolyte ◽

Prussian Blue Analog ◽

Operating Potential

<div><div><div><p>Potassium-ion batteries (KIB) are a promising complementary technology to lithium-ion batteries because of the comparative abundance and affordability of potassium. Currently, the most promising KIB chemistry consists of a potassium manganese hexacyanoferrate (KMF) cathode, a Prussian blue analog, and a graphite anode (723Whl−1 and 359Whkg−1 at 3.6V). No electrolyte has yet been formulated that is concurrently stable at the high operating potential of KMF (4.02V vs K+/K) and compatible with K+ intercalation into graphite, currently the most critical hurdle to adoption. Here we combine a KMF cathode and a graphite anode with a KFSI in Pyr1,3FSI ionic liquid electrolyte for the first time and show unprecedented performance. We use high-throughput techniques to optimize the KMF morphology for operation in this electrolyte system, achieving 119 mA h g−1 at 4 V vs K+/K and a coulombic efficiency >99.3%. In the same ionic liquid electrolyte graphite shows excellent electrochemical performance and we demonstrate reversible cycling by operando XRD. These results are a significant and essential step forward towards viable potassium-ion batteries.</p></div></div></div>

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High energy supercapattery with an ionic liquid solution of LiClO4

Faraday Discussions ◽

10.1039/c5fd00232j ◽

2016 ◽

Vol 190 ◽

pp. 231-240 ◽

Cited By ~ 37

Author(s):

Linpo Yu ◽

George Z. Chen

Keyword(s):

Ionic Liquid ◽

Negative Electrode ◽

Liquid Solution ◽

High Energy ◽

Liquid Electrolyte ◽

Positive Electrode ◽

Lithium Metal ◽

Discharge Current Density ◽

Ionic Liquid Electrolyte ◽

Ionic Liquid Solution

A supercapattery combining an ideally polarized capacitor-like electrode and a battery-like electrode is demonstrated theoretically and practically using an ionic liquid electrolyte containing 1-butyl-1-methylpyrrolidinium tri(pentafluoroethyl)trifluorophosphate (BMPyrrFAP), gamma-butyrolactone (γ-GBL) and LiClO4. The electrochemical deposition and dissolution of lithium metal on a platinum and glass carbon electrode were investigated in this ionic liquid solution. The CVs showed that the fresh electrochemically deposited lithium metal was stable in the electrolyte, which encouraged the investigation of this ionic liquid solution in a supercapattery with a lithium battery negative electrode. The active material counted specific energy of the supercapattery based on a lithium negative electrode and an activated carbon (Act-C) positive electrode could reach 230 W h kg−1 under a galvanostatic charge–discharge current density of 1 mA cm−2. The positive electrode material (Act-C) was also investigated by CV, AC impedance, SEM and BET. The non-uniform particle size and micropores dominated porous structure of the Act-C enabled its electric double layer capacitor (EDLC) behavior in the ionic liquid solution. The measured specific capacitance of the Act-C in this ionic liquid solution is higher than the same Act-C in aqueous solution, which indicates the Act-C can also perform well in the ionic liquid electrolyte.

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