Supporting Information High-Energy-Density Lithium-Sulfur Batteries ...
Supporting Information High-Energy-Density Lithium-Sulfur Batteries Based on a Blade-Cast Pure Sulfur Electrodes Long Qie, Arumugam Manthiram*
Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA Corresponding Author *E-mail: [email protected]
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Experimental Method Preparation of upper carbon current collector: Activated carbon nanofiber sheets were used as an upper current collector. The activated carbon nanofiber sheets were prepared via vacuumfiltration, peel-off, and CO2-activation processes as previously reported.1 By controlling the thicknesses of the original carbon nanofiber paper, activated carbon sheets with areal densities from 0.5 to 15.0 mg cm−2 could be readily obtained. Characterizations: SEM images and EDX elemental analysis were performed with a FEI Quanta 650 field-emission scanning electron microscope. XRD patterns of the cycled carbon upper current collectors (protected with a Kapton film) were collected on a Rikagu MiniFlex 600 X-ray diffractometer equipped with Cu Kα radiation between 10 to 80 º at a scan rate of 3 º min–1. Fabrication of the pure sulfur electrode: 0.95 g of commercial sulfur powder and 0.05 g of PVDF were mixed and dispersed in NMP, and then coated using the doctor blade method onto an aluminum foil substrate. Prior to testing, this cathode was dried in an oven at 50 °C under vacuum overnight and cut into circular disks. By controlling the amount of NMP solvent, the punched circular cathodes with an areal sulfur loading of up to 16.2 mg cm–2 could be easily obtained. Electrochemical Measurements: The electrochemical tests were performed with CR2032-type coin cells with the pure sulfur electrodes and lithium-metal chips separated by a Celgard 2400 separator. A solution of 0.1 M lithium trifluoromethanesulfonate (LiCF3SO3) and 0.1 M lithium nitrate (LiNO3) dissolved in dimethoxyethane/1,3-dioxolane (DME/DOL, 1 : 1 by volume) were used as the electrolyte. To suppress the diffusion of the dissolved soluble intermediate products (Li2S4˗8) to the lithium anode, an activated carbon nanofiber sheet was placed over the pure sulfur electrode as an upper current collector. The carbon sheet was adjusted to keep the sulfur content in all the cathodes (including sulfur, PVDF binder, and upper carbon current collector) around 55 2
wt. %. The electrolyte-to-sulfur ratio for the coin cell was fixed to around 15. The Li–S pouch cell was assembled using the same electrolyte. A pure sulfur cathode (area: 12 cm2) with an aluminum tab was placed with an upper carbon current collector over it. A separator (Celgard 2400) was placed over the carbon upper current collector and a lithium foil (with a nickel tab) was placed on the top of it. The pouch cell was sealed with an aluminum soft packaging film. The electrolyte-to-sulfur ratio for the pouch cell was 8. The galvanostatic discharge/charge tests were carried out with an Arbin battery test station at different C rates (1C = 1675 mA g−1), and all the capacity values were calculated based on the weight of sulfur in the cathode. Galvanostatic intermittent titration technique (GITT) profiles were recorded by applying a constant current (C/50) for 1 h, followed by a resting step of 1 h.
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Figure S1. Photographs of the sulfur@carbon composite cathode (super P: 30 wt. %, PTFE: 15 wt. %, S: 55 wt. %, S areal loading: ~ 7 mg cm−2) and pure sulfur (PTFE: 5 wt. %, S: 95 wt. %, S areal loading: ~ 12 mg cm−2) electrodes before and after folding.
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Figure S2. Electrochemical performance of pure sulfur electrodes with a sulfur loading of 2.7 mg cm−2: (a) discharge/charge curves at different C rates, (b) rate performance, and (c) cycling performance at a C/3 rate.
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Figure S3 (a) Photograph of a pure sulfur electrode in pouch cell configuration and (b) initial discharge/charge curves of a pouch cell with pure sulfur cathode cycled at a C/20 rate.
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Figure S4. (a) Schematic representations for the distribution of sulfur throughout the carbon paper assembled with the pure sulfur electrode during cycling, and SEM images of the upper carbon-paper current collector (b) facing the pure sulfur cathode side and (c) facing the separator side after 10 cycles (fully discharged state).
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Figure S5. XRD pattern of the upper carbon-paper current collector assembled with a pure sulfur cathode collected from (a) the side facing the pure sulfur cathode and (b) the side facing the separator after 10 cycles (fully discharged state).
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Figure S6. EDX spectra of the upper carbon-paper current collector assembled with a pure sulfur cathode collected from (a) the side facing the pure sulfur cathode and (b) the side facing the separator after 10 cycles (fully discharged state).
1.
Qie, L.; Manthiram, A. A Facile Layer-by-Layer Approach for High-Areal-Capacity
Sulfur Cathodes. Adv Mater 2015, 27, 1694–1700.
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Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, TX 78712, USA Corresponding Author *E-mail: [email protected]
1
Experimental Method Preparation of upper carbon current collector: Activated carbon nanofiber sheets were used as an upper current collector. The activated carbon nanofiber sheets were prepared via vacuumfiltration, peel-off, and CO2-activation processes as previously reported.1 By controlling the thicknesses of the original carbon nanofiber paper, activated carbon sheets with areal densities from 0.5 to 15.0 mg cm−2 could be readily obtained. Characterizations: SEM images and EDX elemental analysis were performed with a FEI Quanta 650 field-emission scanning electron microscope. XRD patterns of the cycled carbon upper current collectors (protected with a Kapton film) were collected on a Rikagu MiniFlex 600 X-ray diffractometer equipped with Cu Kα radiation between 10 to 80 º at a scan rate of 3 º min–1. Fabrication of the pure sulfur electrode: 0.95 g of commercial sulfur powder and 0.05 g of PVDF were mixed and dispersed in NMP, and then coated using the doctor blade method onto an aluminum foil substrate. Prior to testing, this cathode was dried in an oven at 50 °C under vacuum overnight and cut into circular disks. By controlling the amount of NMP solvent, the punched circular cathodes with an areal sulfur loading of up to 16.2 mg cm–2 could be easily obtained. Electrochemical Measurements: The electrochemical tests were performed with CR2032-type coin cells with the pure sulfur electrodes and lithium-metal chips separated by a Celgard 2400 separator. A solution of 0.1 M lithium trifluoromethanesulfonate (LiCF3SO3) and 0.1 M lithium nitrate (LiNO3) dissolved in dimethoxyethane/1,3-dioxolane (DME/DOL, 1 : 1 by volume) were used as the electrolyte. To suppress the diffusion of the dissolved soluble intermediate products (Li2S4˗8) to the lithium anode, an activated carbon nanofiber sheet was placed over the pure sulfur electrode as an upper current collector. The carbon sheet was adjusted to keep the sulfur content in all the cathodes (including sulfur, PVDF binder, and upper carbon current collector) around 55 2
wt. %. The electrolyte-to-sulfur ratio for the coin cell was fixed to around 15. The Li–S pouch cell was assembled using the same electrolyte. A pure sulfur cathode (area: 12 cm2) with an aluminum tab was placed with an upper carbon current collector over it. A separator (Celgard 2400) was placed over the carbon upper current collector and a lithium foil (with a nickel tab) was placed on the top of it. The pouch cell was sealed with an aluminum soft packaging film. The electrolyte-to-sulfur ratio for the pouch cell was 8. The galvanostatic discharge/charge tests were carried out with an Arbin battery test station at different C rates (1C = 1675 mA g−1), and all the capacity values were calculated based on the weight of sulfur in the cathode. Galvanostatic intermittent titration technique (GITT) profiles were recorded by applying a constant current (C/50) for 1 h, followed by a resting step of 1 h.
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Figure S1. Photographs of the sulfur@carbon composite cathode (super P: 30 wt. %, PTFE: 15 wt. %, S: 55 wt. %, S areal loading: ~ 7 mg cm−2) and pure sulfur (PTFE: 5 wt. %, S: 95 wt. %, S areal loading: ~ 12 mg cm−2) electrodes before and after folding.
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Figure S2. Electrochemical performance of pure sulfur electrodes with a sulfur loading of 2.7 mg cm−2: (a) discharge/charge curves at different C rates, (b) rate performance, and (c) cycling performance at a C/3 rate.
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Figure S3 (a) Photograph of a pure sulfur electrode in pouch cell configuration and (b) initial discharge/charge curves of a pouch cell with pure sulfur cathode cycled at a C/20 rate.
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Figure S4. (a) Schematic representations for the distribution of sulfur throughout the carbon paper assembled with the pure sulfur electrode during cycling, and SEM images of the upper carbon-paper current collector (b) facing the pure sulfur cathode side and (c) facing the separator side after 10 cycles (fully discharged state).
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Figure S5. XRD pattern of the upper carbon-paper current collector assembled with a pure sulfur cathode collected from (a) the side facing the pure sulfur cathode and (b) the side facing the separator after 10 cycles (fully discharged state).
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Figure S6. EDX spectra of the upper carbon-paper current collector assembled with a pure sulfur cathode collected from (a) the side facing the pure sulfur cathode and (b) the side facing the separator after 10 cycles (fully discharged state).
1.
Qie, L.; Manthiram, A. A Facile Layer-by-Layer Approach for High-Areal-Capacity
Sulfur Cathodes. Adv Mater 2015, 27, 1694–1700.
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