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

Author(s):  
Fanglin Wu ◽  
Annika Regitta Schür ◽  
Guk-Tae Kim ◽  
Xu Dong ◽  
Matthias Kuenzel ◽  
...  
2016 ◽  
Vol 190 ◽  
pp. 231-240 ◽  
Author(s):  
Linpo Yu ◽  
George Z. Chen

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.


2020 ◽  
Vol 32 (26) ◽  
pp. 2001741 ◽  
Author(s):  
Hao Sun ◽  
Guanzhou Zhu ◽  
Yuanmin Zhu ◽  
Meng‐Chang Lin ◽  
Hui Chen ◽  
...  

2020 ◽  
Author(s):  
Urbi Pal ◽  
Fangfang Chen ◽  
Derick Gyabang ◽  
Thushan Pathirana ◽  
Binayak Roy ◽  
...  

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.


2021 ◽  
Author(s):  
Thushan Pathirana ◽  
Dmitrii Rakov ◽  
Fangfang Chen ◽  
Maria Forsyth ◽  
Robert Kerr ◽  
...  

<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>


Author(s):  
Thushan Pathirana ◽  
Robert Kerr ◽  
Maria Forsyth ◽  
Patrick C. Howlett

Anode-free lithium metal batteries based on ionic liquid electrolytes offer an excellent pathway to significantly boost the energy density and specific energy over current lithium-ion technology by eliminating the anode material during cell assembly.


2020 ◽  
Author(s):  
Hyeon Jeong Lee ◽  
Zachary Brown ◽  
Ying Zhao ◽  
Jack Fawdon ◽  
Weixin Song ◽  
...  

<div><div><div><p>The high voltage (4.7 V vs. Li+ /Li) spinel lithium nickel manganese oxide (LiNi0.5 Mn1.5 O4 , LNMO) is a promising candidate for the next-generation of lithium ion batteries due to its high energy density, low cost and environmental impact. However, poor cycling performance at high cutoff potentials limits its commercialization. Herein, hollow structured LNMO is synergistically paired with an ionic liquid electrolyte, 1M lithium bis(fluorosulfonyl)imide (LiFSI) in N-propyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide (Pyr1,3 FSI) to achieve stable cycling performance and improved rate capability. The optimized cathode-electrolyte system exhibits extended cycling performance (>85% capacity retention after 300 cycles) and high rate performance (106.2mAhg–1 at 5C) even at an elevated temperature of 65 ◦C. X-ray photoelectron spectroscopy and spatially resolved x-ray fluorescence analyses confirm the formation of a robust, LiF-rich cathode electrolyte interphase. This study presents a comprehensive design strategy to improve the electrochemical performance of high-voltage cathode materials.</p></div></div></div>


2010 ◽  
Vol 114 (49) ◽  
pp. 21775-21785 ◽  
Author(s):  
George H. Lane ◽  
Paul M. Bayley ◽  
Bronya R. Clare ◽  
Adam S. Best ◽  
Douglas R. MacFarlane ◽  
...  

Joule ◽  
2021 ◽  
Author(s):  
Fanglin Wu ◽  
Shan Fang ◽  
Matthias Kuenzel ◽  
Angelo Mullaliu ◽  
Jae-Kwang Kim ◽  
...  

2021 ◽  
Author(s):  
Thushan Pathirana ◽  
Dmitrii Rakov ◽  
Fangfang Chen ◽  
Maria Forsyth ◽  
Robert Kerr ◽  
...  

<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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