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The lithium–sulfur cell is considered to be the most promising next-generation energy storage system. However, the practical use of Li–S batteries is hindered by several problems such as poor cycle retention, low Coulombic efficiency, low sulfur loading, and so forth. We herein for the first-time propose nitrogen-doped graphene quantum dots as the sulfiphilic additive for the advancement of Li–S cell performance. We carry out direct decoration of conducting additives and carbon cloth interlayers with graphene quantum dots and nitrogen-doped graphene quantum dots, which are evaluated in Li–S cells. Nitrogen-doped graphene quantum dots exhibit strong sulfiphilic properties, and therefore, they anchor the liquid-phase polysulfides. The Li–S cell using the nitrogen-doped graphene quantum dot-decorated carbon cloth interlayer shows a discharge capacity of 1454.4 mA h gS–1 at 0.1 C and a capacity retention of 98.2% at 0.5 C after 300 cycles even with a sulfur loading of 6.0 mg S cm–2. Our study demonstrates that the nitrogen-doped graphene quantum dot is a promising additive, which can improve the viability of Li–S cells for the next generation of energy storage systems.
JungJin Park; Joonhee Moon; Vitalii Ri; Sangheon Lee; Chunjoong Kim; Elton J. Cairns. Nitrogen-Doped Graphene Quantum Dots: Sulfiphilic Additives for the High-Performance Li–S Cells. ACS Applied Energy Materials 2021, 4, 3518 -3525.
AMA StyleJungJin Park, Joonhee Moon, Vitalii Ri, Sangheon Lee, Chunjoong Kim, Elton J. Cairns. Nitrogen-Doped Graphene Quantum Dots: Sulfiphilic Additives for the High-Performance Li–S Cells. ACS Applied Energy Materials. 2021; 4 (4):3518-3525.
Chicago/Turabian StyleJungJin Park; Joonhee Moon; Vitalii Ri; Sangheon Lee; Chunjoong Kim; Elton J. Cairns. 2021. "Nitrogen-Doped Graphene Quantum Dots: Sulfiphilic Additives for the High-Performance Li–S Cells." ACS Applied Energy Materials 4, no. 4: 3518-3525.
Lithium/sulfur (Li/S) cells that offer high theoretical specific energy (2600 Wh/kg) have been considered for emerging high energy applications. Significant progress in improving the electrochemical performance of Li/S cells has been made based on the development strategies of the nano‐structured sulfur‐based electrodes: (i) improving the electrical conduction pathway by confining sulfur particles with conductive media, (ii) employing sulfur‐philic functional nano‐materials to retain sulfur species in the sulfur electrode (iii) constructing rationally designed porous sulfur electrodes to accommodate large amounts of sulfur while maintaining good electronic and ionic conduction pathways. In this review, recent innovations on nanostructured sulfur‐based materials with an emphasis on their nanostructure and reactivity and microstructural design strategies of the sulfur electrode will be highlighted, and future directions to advance the sulfur electrode for commercially viable Li/S cells will be discussed.
Yoon Hwa; Elton J. Cairns. Nano‐structured Sulfur and Sulfides for Advanced Lithium/Sulfur Cells. ChemElectroChem 2020, 7, 1 .
AMA StyleYoon Hwa, Elton J. Cairns. Nano‐structured Sulfur and Sulfides for Advanced Lithium/Sulfur Cells. ChemElectroChem. 2020; 7 (19):1.
Chicago/Turabian StyleYoon Hwa; Elton J. Cairns. 2020. "Nano‐structured Sulfur and Sulfides for Advanced Lithium/Sulfur Cells." ChemElectroChem 7, no. 19: 1.
Understanding of lithium polysulfide (Li-PS) formation and the shuttle phenomenon is essential for practical application of the lithium/sulfur (Li/S) cell, which has superior theoretical specific energy (2600 Wh/kg). However, it suffers from the lack of direct observation on behaviors of soluble Li-PS in liquid electrolytes. Using in situ graphene liquid cell electron microscopy, we have visualized formation and diffusion of Li-PS simultaneous with morphological and phase evolutions of sulfur nanoparticles during lithiation. We found that the morphological changes and Li-PS diffusion are retarded by ionic liquid (IL) addition into electrolyte. Chronoamperometric shuttle current measurement confirms that IL addition lowers the experimental diffusion coefficient of Li-PS by two orders of magnitude relative to that in IL-free electrolyte, and thus suppresses the Li-PS shuttle current, which accounts for better cyclability and Coulombic efficiency of the Li/S cell. This study provides significant insights into electrolyte design to inhibit the polysulfide shuttle phenomenon.
Hyeon Kook Seo; Yoon Hwa; Joon Ha Chang; Jae Yeol Park; Jae Sang Lee; Jungjae Park; Elton J. Cairns; Jong Min Yuk. Direct Visualization of Lithium Polysulfides and Their Suppression in Liquid Electrolyte. Nano Letters 2020, 20, 2080 -2086.
AMA StyleHyeon Kook Seo, Yoon Hwa, Joon Ha Chang, Jae Yeol Park, Jae Sang Lee, Jungjae Park, Elton J. Cairns, Jong Min Yuk. Direct Visualization of Lithium Polysulfides and Their Suppression in Liquid Electrolyte. Nano Letters. 2020; 20 (3):2080-2086.
Chicago/Turabian StyleHyeon Kook Seo; Yoon Hwa; Joon Ha Chang; Jae Yeol Park; Jae Sang Lee; Jungjae Park; Elton J. Cairns; Jong Min Yuk. 2020. "Direct Visualization of Lithium Polysulfides and Their Suppression in Liquid Electrolyte." Nano Letters 20, no. 3: 2080-2086.
A (calculated) high specific energy of 325 W h kg−1 is achieved via a rational design of a sulfur–carbonaceous composite electrode.
Yoon Hwa; Hyo Won Kim; Hao Shen; Dilworth Y. Parkinson; Bryan D. McCloskey; Elton J. Cairns. A sustainable sulfur–carbonaceous composite electrode toward high specific energy rechargeable cells. Materials Horizons 2019, 7, 524 -529.
AMA StyleYoon Hwa, Hyo Won Kim, Hao Shen, Dilworth Y. Parkinson, Bryan D. McCloskey, Elton J. Cairns. A sustainable sulfur–carbonaceous composite electrode toward high specific energy rechargeable cells. Materials Horizons. 2019; 7 (2):524-529.
Chicago/Turabian StyleYoon Hwa; Hyo Won Kim; Hao Shen; Dilworth Y. Parkinson; Bryan D. McCloskey; Elton J. Cairns. 2019. "A sustainable sulfur–carbonaceous composite electrode toward high specific energy rechargeable cells." Materials Horizons 7, no. 2: 524-529.
To date, Li2S has drawn significant attention as a positive electrode active material for rechargeable lithium cells due to its high theoretical specific capacity and capability of pairing with a lithium-free anode which can obviate any safety concern of the lithium metal anode when using sulfur. In recent years, various approaches have been employed to develop Li/Li2S rechargeable cells for commercialization that meet the performance goals for high energy/power applications. It is expected that high lithium sulfide-loading cells with long cycle life, an excellent capacity delivery and low electrolyte:sulfur weight ratio (E/S ratio) can be achieved. Here, we report a Li2S electrode comprised of a novel Li2S/[email protected] nanocomposite which delivers an areal capacity of 7.56 mAh cm-2 and good cycling stability with a mass loading of 11.29 mg cm-2 and a robust 3-dimensional (3D) aluminum foam current collector with a high open area. The high conductivity and scalability of the active material, the availability of 3D current collection for the active material and the control of the electrolyte/sulfur ratio offer the potential of realization of practical Li/S cells.
Dan Sun; Yoon Hwa; Liang Zhang; Jingwei Xiang; Jinghua Guo; Yunhui Huang; Elton J. Cairns. High lithium sulfide loading electrodes for practical Li/S cells with high specific energy. Nano Energy 2019, 64, 103891 .
AMA StyleDan Sun, Yoon Hwa, Liang Zhang, Jingwei Xiang, Jinghua Guo, Yunhui Huang, Elton J. Cairns. High lithium sulfide loading electrodes for practical Li/S cells with high specific energy. Nano Energy. 2019; 64 ():103891.
Chicago/Turabian StyleDan Sun; Yoon Hwa; Liang Zhang; Jingwei Xiang; Jinghua Guo; Yunhui Huang; Elton J. Cairns. 2019. "High lithium sulfide loading electrodes for practical Li/S cells with high specific energy." Nano Energy 64, no. : 103891.
Rational design of sulfur electrodes is exceptionally important in enabling a high-performance lithium/sulfur cell. Constructing a continuous pore structure of the sulfur electrode that enables facile lithium ion transport into the electrode and mitigates the reconstruction of sulfur is a key factor for enhancing the electrochemical performance. Here, we report a three-dimensionally (3D) aligned sulfur electrode cast onto conventional aluminum foil by directional freeze tape casting. The 3D aligned sulfur–graphene oxide (S–GO) electrode consisting of few micron thick S–GO layers with 10–20 μm interlayer spacings demonstrates significant improvement in the performance of the Li/S cell. Moreover, the freeze tape cast graphene oxide electrode exhibits homogeneous reconfiguration behavior in the polysulfide catholyte cell tests and demonstrated extended cycling capability with only 4% decay of the specific capacity over 200 cycles. This work emphasizes the critical importance of proper structural design for sulfur–carbonaceous composite electrodes.
Yoon Hwa; Eongyu Yi; Hao Shen; Younghoon Sung; Jiawei Kou; Kai Chen; Dilworth Y. Parkinson; Marca M. Doeff; Elton J. Cairns. Three-Dimensionally Aligned Sulfur Electrodes by Directional Freeze Tape Casting. Nano Letters 2019, 19, 4731 -4737.
AMA StyleYoon Hwa, Eongyu Yi, Hao Shen, Younghoon Sung, Jiawei Kou, Kai Chen, Dilworth Y. Parkinson, Marca M. Doeff, Elton J. Cairns. Three-Dimensionally Aligned Sulfur Electrodes by Directional Freeze Tape Casting. Nano Letters. 2019; 19 (7):4731-4737.
Chicago/Turabian StyleYoon Hwa; Eongyu Yi; Hao Shen; Younghoon Sung; Jiawei Kou; Kai Chen; Dilworth Y. Parkinson; Marca M. Doeff; Elton J. Cairns. 2019. "Three-Dimensionally Aligned Sulfur Electrodes by Directional Freeze Tape Casting." Nano Letters 19, no. 7: 4731-4737.
High capacity and long cycle life are both desirable features for practical secondary cells. In this study, we compare two different synthesis processes for preparing active materials for lithium/sulfur cells using polysulfide and graphene oxide (GO) showing high sulfur utilization and cycling stability. The key factor determining cell performance is the oxygen-containing functional groups on GO and the fine structures. This study shows the possibility of application of GO for enhanced capacity and cycling stability.
Ayako Kawase; Elton J. Cairns. Method for Creation of Fine Sulfur Particles with Graphene Oxide for Lithium/Sulfur Cells. Journal of The Electrochemical Society 2018, 165, A3257 -A3262.
AMA StyleAyako Kawase, Elton J. Cairns. Method for Creation of Fine Sulfur Particles with Graphene Oxide for Lithium/Sulfur Cells. Journal of The Electrochemical Society. 2018; 165 (14):A3257-A3262.
Chicago/Turabian StyleAyako Kawase; Elton J. Cairns. 2018. "Method for Creation of Fine Sulfur Particles with Graphene Oxide for Lithium/Sulfur Cells." Journal of The Electrochemical Society 165, no. 14: A3257-A3262.
Liang Zhang; Dan Sun; Qiulong Wei; Huanxin Ju; Jun Feng; Junfa Zhu; Liqiang Mai; Elton J. Cairns; Jinghua Guo. Understanding the electrochemical reaction mechanism of VS2 nanosheets in lithium-ion cells by multiple in situ and ex situ x-ray spectroscopy. Journal of Physics D: Applied Physics 2018, 51, 494001 .
AMA StyleLiang Zhang, Dan Sun, Qiulong Wei, Huanxin Ju, Jun Feng, Junfa Zhu, Liqiang Mai, Elton J. Cairns, Jinghua Guo. Understanding the electrochemical reaction mechanism of VS2 nanosheets in lithium-ion cells by multiple in situ and ex situ x-ray spectroscopy. Journal of Physics D: Applied Physics. 2018; 51 (49):494001.
Chicago/Turabian StyleLiang Zhang; Dan Sun; Qiulong Wei; Huanxin Ju; Jun Feng; Junfa Zhu; Liqiang Mai; Elton J. Cairns; Jinghua Guo. 2018. "Understanding the electrochemical reaction mechanism of VS2 nanosheets in lithium-ion cells by multiple in situ and ex situ x-ray spectroscopy." Journal of Physics D: Applied Physics 51, no. 49: 494001.
Sulfur deposition is an effective method for creating composites of sulfur with various conductive materials. In this study we investigated the details of the deposition process of sulfur onto graphene oxide (GO). It was revealed that just mixing a polysulfide solution and a GO suspension resulted in the deposition of sulfur onto the GO under alkaline conditions. The combination of the alkaline deposition and subsequent acidic deposition at different temperatures yielded materials with various morphologies. The sulfur deposition rate influenced the morphology of the S deposit and the resulting Li/S cell performance. By controlling the process with a moderate time for the alkaline deposition and subsequent acidic deposition at a decreased temperature, a preferred morphology of the sulfur/GO composite with a high sulfur utilization was successfully synthesized. This preferred morphology of SGO provides for a high-performance Li/S cell.
Ayako Kawase; Don Donghyeok Han; Elton J. Cairns. Low Temperature Sulfur Deposition for High-Performance Lithium/Sulfur Cells. Journal of The Electrochemical Society 2018, 165, A1805 -A1812.
AMA StyleAyako Kawase, Don Donghyeok Han, Elton J. Cairns. Low Temperature Sulfur Deposition for High-Performance Lithium/Sulfur Cells. Journal of The Electrochemical Society. 2018; 165 (9):A1805-A1812.
Chicago/Turabian StyleAyako Kawase; Don Donghyeok Han; Elton J. Cairns. 2018. "Low Temperature Sulfur Deposition for High-Performance Lithium/Sulfur Cells." Journal of The Electrochemical Society 165, no. 9: A1805-A1812.
As the lightest and cheapest transition metal dichalcogenide, TiS2 possesses great potential as an electrode material for lithium batteries due to the advantages of high energy density storage capability, fast ion diffusion rate, and low volume expansion. Despite the extensive investigation of its electrochemical properties, the fundamental discharge–charge reaction mechanism of the TiS2 electrode is still elusive. Here, by a combination of ex situ and operando X-ray absorption spectroscopy with density functional theory calculations, we have clearly elucidated the evolution of the structural and chemical properties of TiS2 during the discharge–charge processes. The lithium intercalation reaction is highly reversible and both Ti and sulfur are involved in the redox reaction during the discharge and charge processes. In contrast, the conversion reaction of TiS2 is partially reversible in the first cycle. However, Ti—O related compounds are developed during electrochemical cycling over extended cycles, which results in the decrease of the conversion reaction reversibility and the rapid capacity fading. In addition, the solid electrolyte interphase formed on the electrode surface is found to be highly dynamic in the initial cycles and then gradually becomes more stable upon further cycling. Such understanding is important for the future design and optimization of TiS2 based electrodes for lithium batteries.
Liang Zhang; Dan Sun; Jun Kang; Hsiao-Tsu Wang; Shang-Hsien Hsieh; Way-Faung Pong; Hans A. Bechtel; Jun Feng; Lin-Wang Wang; Elton J. Cairns; Jinghua Guo. Tracking the Chemical and Structural Evolution of the TiS2 Electrode in the Lithium-Ion Cell Using Operando X-ray Absorption Spectroscopy. Nano Letters 2018, 18, 4506 -4515.
AMA StyleLiang Zhang, Dan Sun, Jun Kang, Hsiao-Tsu Wang, Shang-Hsien Hsieh, Way-Faung Pong, Hans A. Bechtel, Jun Feng, Lin-Wang Wang, Elton J. Cairns, Jinghua Guo. Tracking the Chemical and Structural Evolution of the TiS2 Electrode in the Lithium-Ion Cell Using Operando X-ray Absorption Spectroscopy. Nano Letters. 2018; 18 (7):4506-4515.
Chicago/Turabian StyleLiang Zhang; Dan Sun; Jun Kang; Hsiao-Tsu Wang; Shang-Hsien Hsieh; Way-Faung Pong; Hans A. Bechtel; Jun Feng; Lin-Wang Wang; Elton J. Cairns; Jinghua Guo. 2018. "Tracking the Chemical and Structural Evolution of the TiS2 Electrode in the Lithium-Ion Cell Using Operando X-ray Absorption Spectroscopy." Nano Letters 18, no. 7: 4506-4515.
A novel ionic liquid-containing electrolyte has been demonstrated to improve charging efficiency, lifetime and safety of Li/S cells. However, the high viscosity of the ionic liquid can reduce the kinetics of the electrochemical process and degrade the wettability the S electrode by the electrolyte, which limits electrochemical utilization of the active S. To realize the advantages of the ionic liquid in the electrolyte, while maintaining good cell performances, we have investigated the critical properties of polymeric binders such as polyvinylidene fluoride (PVDF), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), polyacrylic acid (PAA) and lithium polyacrylate (LiPAA) for the S electrode operated in ionic liquid-containing electrolytes. The PAA binder electrode showed the most promising cell performance which is attributed to its good physical stability and wettability. Moreover, the cell performance of the PAA binder electrode was further improved by combining the PAA binder with the PVDF binder, which enhances the specific capacity up to 1.3 times higher than that of the PAA binder electrode.
Yoon Hwa; Elton J. Cairns. Polymeric binders for the sulfur electrode compatible with ionic liquid containing electrolytes. Electrochimica Acta 2018, 271, 103 -109.
AMA StyleYoon Hwa, Elton J. Cairns. Polymeric binders for the sulfur electrode compatible with ionic liquid containing electrolytes. Electrochimica Acta. 2018; 271 ():103-109.
Chicago/Turabian StyleYoon Hwa; Elton J. Cairns. 2018. "Polymeric binders for the sulfur electrode compatible with ionic liquid containing electrolytes." Electrochimica Acta 271, no. : 103-109.
Lithium/Sulfur (Li/S) cells are a promising chemistry with potential to deliver a step-change in energy density compared to state-of-the-art Li-ion batteries. To minimize the environmental impact of the Li/S cell manufacturing and to compete with Li-ion cells in both performance and cost, electrodes cast using an aqueous process are highly desirable. Here we describe the discovery and application of a lithiated redox-mediating supramolecular binder based on the well-known n-type semiconductor, perylene bisimide, that forms high-fidelity sulfur electrodes from water-processed slurries. A 1.4-fold improvement in sulfur utilization at 3.0 C and 58% increase in capacity retention after 250 cycles at 1.5 C are reported for the pre-lithiated, supramolecular binder compared to control samples. These improvements are attributed to the self-assembly of lithiated perylene bisimide binders in water to yield nanowire web morphologies that increase interfacial area between electrode components and exhibit enhanced electrode-current collector adhesion.
Yoon Hwa; Peter D. Frischmann; Brett A. Helms; Elton J. Cairns. Aqueous-Processable Redox-Active Supramolecular Polymer Binders for Advanced Lithium/Sulfur Cells. Chemistry of Materials 2018, 30, 685 -691.
AMA StyleYoon Hwa, Peter D. Frischmann, Brett A. Helms, Elton J. Cairns. Aqueous-Processable Redox-Active Supramolecular Polymer Binders for Advanced Lithium/Sulfur Cells. Chemistry of Materials. 2018; 30 (3):685-691.
Chicago/Turabian StyleYoon Hwa; Peter D. Frischmann; Brett A. Helms; Elton J. Cairns. 2018. "Aqueous-Processable Redox-Active Supramolecular Polymer Binders for Advanced Lithium/Sulfur Cells." Chemistry of Materials 30, no. 3: 685-691.
As a typical transition metal dichalcogenide, MoS2 offers numerous advantages for nanoelectronics and electrochemical energy storage due to its unique layered structure and tunable electronic properties. When used as the anode in lithium-ion cells, MoS2 undergoes intercalation and conversion reactions in sequence upon lithiation, and the reversibility of the conversion reaction is an important but still controversial topic. Here, we clarify unambiguously that the conversion reaction of MoS2 is not reversible and the formed Li2S is converted to sulfur in the first charge process. Li2S/sulfur becomes the main redox couple in the subsequent cycles and the main contributor to the reversible capacity. In addition, due to the insulating nature of both Li2S and sulfur, a strong relaxation effect is observed during the cycling process. This study clearly reveals the electrochemical lithiation/delithiation mechanism of MoS2, which can facilitate further developments of high-performance MoS2 based electrodes.
Liang Zhang; Dan Sun; Jun Kang; Jun Feng; Hans A. Bechtel; Lin-Wang Wang; Elton J. Cairns; Jinghua Guo. Electrochemical Reaction Mechanism of the MoS2 Electrode in a Lithium-Ion Cell Revealed by in Situ and Operando X-ray Absorption Spectroscopy. Nano Letters 2018, 18, 1466 -1475.
AMA StyleLiang Zhang, Dan Sun, Jun Kang, Jun Feng, Hans A. Bechtel, Lin-Wang Wang, Elton J. Cairns, Jinghua Guo. Electrochemical Reaction Mechanism of the MoS2 Electrode in a Lithium-Ion Cell Revealed by in Situ and Operando X-ray Absorption Spectroscopy. Nano Letters. 2018; 18 (2):1466-1475.
Chicago/Turabian StyleLiang Zhang; Dan Sun; Jun Kang; Jun Feng; Hans A. Bechtel; Lin-Wang Wang; Elton J. Cairns; Jinghua Guo. 2018. "Electrochemical Reaction Mechanism of the MoS2 Electrode in a Lithium-Ion Cell Revealed by in Situ and Operando X-ray Absorption Spectroscopy." Nano Letters 18, no. 2: 1466-1475.
A surfactant material plays a significant role in creating a sulfur/carbon composite for lithium/sulfur cells.
Ayako Kawase; Elton J. Cairns. Understanding the function of cetyltrimethyl ammonium bromide in lithium/sulfur cells. Journal of Materials Chemistry A 2017, 5, 23094 -23102.
AMA StyleAyako Kawase, Elton J. Cairns. Understanding the function of cetyltrimethyl ammonium bromide in lithium/sulfur cells. Journal of Materials Chemistry A. 2017; 5 (44):23094-23102.
Chicago/Turabian StyleAyako Kawase; Elton J. Cairns. 2017. "Understanding the function of cetyltrimethyl ammonium bromide in lithium/sulfur cells." Journal of Materials Chemistry A 5, no. 44: 23094-23102.
The ambient-temperature rechargeable lithium/sulfur (Li/S) cell is a strong candidate for the beyond lithium ion cell, since significant progress on developing advanced sulfur electrodes with high sulfur loading has been made. Here we report on a new sulfur electrode active material consisting of a cetyltrimethylammonium bromide-modified sulfur-graphene oxide-carbon nanotube (S-GO-CTA-CNT) nano-composite prepared by freeze drying. We show the real-time formation of nano-crystalline lithium sulfide (Li2S) at the interface between the S-GO-CTA-CNT nano-composite and the liquid electrolyte by in situ TEM observation of the reaction. The combination of GO and CNT helps to maintain the structural integrity of the S-GO-CTA-CNT nano-composite during lithiation/delithiation. A high S loading (11.1 mgS/cm2, 75 %S) S-GO-CTA-CNT electrode was successfully prepared using a 3-D structured Al foam as a substrate and showed good S utilization (1128 mAh/gS corresponding to 12.5 mAh/cm2), even with a very low sulfur to electrolyte weight ratio of 4. Moreover, it was demonstrated that the ionic liquid in the electrolyte improves the Coulombic efficiency and stabilizes the morphology of the Li metal anode.
Yoon Hwa; Hyeon Kook Seo; Jong-Min Yuk; Elton J. Cairns. Freeze-Dried Sulfur–Graphene Oxide–Carbon Nanotube Nanocomposite for High Sulfur-Loading Lithium/Sulfur Cells. Nano Letters 2017, 17, 7086 -7094.
AMA StyleYoon Hwa, Hyeon Kook Seo, Jong-Min Yuk, Elton J. Cairns. Freeze-Dried Sulfur–Graphene Oxide–Carbon Nanotube Nanocomposite for High Sulfur-Loading Lithium/Sulfur Cells. Nano Letters. 2017; 17 (11):7086-7094.
Chicago/Turabian StyleYoon Hwa; Hyeon Kook Seo; Jong-Min Yuk; Elton J. Cairns. 2017. "Freeze-Dried Sulfur–Graphene Oxide–Carbon Nanotube Nanocomposite for High Sulfur-Loading Lithium/Sulfur Cells." Nano Letters 17, no. 11: 7086-7094.
Lithium sulfide (Li2S) is a promising cathode material for lithium–sulfur (Li/S) cells due to its high theoretical specific capacity (1166 mAh g–1) and ability to pair with nonmetallic lithium anodes to avoid potential safety issues. However, when used as the cathode, a high charging voltage (∼4 V versus Li+/Li) is always necessary to activate Li2S in the first charge process, and the voltage profile becomes similar to that of a common sulfur electrode in the following charge processes. In this report, we have prepared an electrode of nanosphere Li2S particles and investigated its charging mechanism of the initial two charge processes by in situ and operando X-ray absorption spectroscopy. The results indicate that Li2S is directly converted to elemental sulfur through a two-phase transformation in the first charge process, while it is oxidized first to polysulfides and then to sulfur in the second charge process. The origin of the different charging mechanisms and corresponding charge-voltage profiles of the first and second charge processes is found to be related to the remaining polysulfides at the end of the first discharge process: they can not only facilitate the charge-transfer process at the Li2S/electrolyte interface but also chemically react with Li2S and act as the polysulfide facilitator for the electrochemical oxidation of Li2S in the following charge processes. Our present study provides a new fundamental understanding of the charging mechanism of the Li2S electrode, which should be of help for the further development of high-performance Li/S cells.
Liang Zhang; Dan Sun; Jun Feng; Elton J. Cairns; Jinghua Guo. Revealing the Electrochemical Charging Mechanism of Nanosized Li2S by in Situ and Operando X-ray Absorption Spectroscopy. Nano Letters 2017, 17, 5084 -5091.
AMA StyleLiang Zhang, Dan Sun, Jun Feng, Elton J. Cairns, Jinghua Guo. Revealing the Electrochemical Charging Mechanism of Nanosized Li2S by in Situ and Operando X-ray Absorption Spectroscopy. Nano Letters. 2017; 17 (8):5084-5091.
Chicago/Turabian StyleLiang Zhang; Dan Sun; Jun Feng; Elton J. Cairns; Jinghua Guo. 2017. "Revealing the Electrochemical Charging Mechanism of Nanosized Li2S by in Situ and Operando X-ray Absorption Spectroscopy." Nano Letters 17, no. 8: 5084-5091.
The following sections are included:
Elton J. Cairns; Yoon Hwa; Rezan Demir-Cakan. Sulfur Cathode. Li-S Batteries 2017, 31 -103.
AMA StyleElton J. Cairns, Yoon Hwa, Rezan Demir-Cakan. Sulfur Cathode. Li-S Batteries. 2017; ():31-103.
Chicago/Turabian StyleElton J. Cairns; Yoon Hwa; Rezan Demir-Cakan. 2017. "Sulfur Cathode." Li-S Batteries , no. : 31-103.
Jun-Chao Zheng; Ya-Dong Han; Dan Sun; Bao Zhang; Elton J. Cairns. In situ-formed LiVOPO 4 @V 2 O 5 core-shell nanospheres as a cathode material for lithium-ion cells. Energy Storage Materials 2017, 7, 48 -55.
AMA StyleJun-Chao Zheng, Ya-Dong Han, Dan Sun, Bao Zhang, Elton J. Cairns. In situ-formed LiVOPO 4 @V 2 O 5 core-shell nanospheres as a cathode material for lithium-ion cells. Energy Storage Materials. 2017; 7 ():48-55.
Chicago/Turabian StyleJun-Chao Zheng; Ya-Dong Han; Dan Sun; Bao Zhang; Elton J. Cairns. 2017. "In situ-formed LiVOPO 4 @V 2 O 5 core-shell nanospheres as a cathode material for lithium-ion cells." Energy Storage Materials 7, no. : 48-55.
The electrolyte, a key component for the successful operation of energy materials, is greatly affected by its solvents. The influence of solvents on the electrochemical performance of a LiFePO4/C composite cathode was investigated at various operating temperatures. The reaction kinetics of the LiFePO4/C composite electrode, including changes of rate capability, redox potential, polarization degree, electrode reaction process, exchange current densities, and activation energies, were evaluated using various techniques. The composition and ratio of solvents greatly affect the electrode kinetics. In the mixed solvents of ethylene carbonate (EC), dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC), EMC is beneficial for the room temperature performance, while the substitution of 20 vol.% of EMC by ethyl acetate (EA) is good for the low temperature performance. When 30 vol.% of DMC is substituted by 10 vol.% of EMC and 20 vol.% of EA, the exchange current density increases from 0.022 to 0.038 mA cm-2 at -20 ºC, while the activation energy of the charge-transfer process decreases from 48.36 to 33.01 kJ mol-1. Possible mechanisms for improving the electrochemical performance using different solvents have been analyzed. These results are significant for the exploration of appropriate electrolytes for the extensive applications of LiFePO4/C composite electrodes.
Guixin Wang; Hanchang Kang; Miao Chen; Kangping Yan; Xueshan Hu; Elton J. Cairns. Effects of Solvents on the Electrochemical Performance of LiFePO4 /C Composite Electrodes. ChemElectroChem 2016, 4, 376 -385.
AMA StyleGuixin Wang, Hanchang Kang, Miao Chen, Kangping Yan, Xueshan Hu, Elton J. Cairns. Effects of Solvents on the Electrochemical Performance of LiFePO4 /C Composite Electrodes. ChemElectroChem. 2016; 4 (2):376-385.
Chicago/Turabian StyleGuixin Wang; Hanchang Kang; Miao Chen; Kangping Yan; Xueshan Hu; Elton J. Cairns. 2016. "Effects of Solvents on the Electrochemical Performance of LiFePO4 /C Composite Electrodes." ChemElectroChem 4, no. 2: 376-385.
π-Stacked perylene bisimide (PBI) molecules are implemented here as highly networked, redox-active supramolecular polymer binders in sulfur cathodes for lightweight and energy-dense Li–S batteries. We show that the in operando reduction and lithiation of these PBI binders sustainably reduces Li–S cell impedance relative to nonredox active conventional polymer binders. This lower impedance enables high-rate cycling in Li–S cells with excellent durability, a critical step toward unlocking the full potential of Li–S batteries for electric vehicles and aviation.
Peter D. Frischmann; Yoon Hwa; Elton J. Cairns; Brett A. Helms. Redox-Active Supramolecular Polymer Binders for Lithium–Sulfur Batteries That Adapt Their Transport Properties in Operando. Chemistry of Materials 2016, 28, 7414 -7421.
AMA StylePeter D. Frischmann, Yoon Hwa, Elton J. Cairns, Brett A. Helms. Redox-Active Supramolecular Polymer Binders for Lithium–Sulfur Batteries That Adapt Their Transport Properties in Operando. Chemistry of Materials. 2016; 28 (20):7414-7421.
Chicago/Turabian StylePeter D. Frischmann; Yoon Hwa; Elton J. Cairns; Brett A. Helms. 2016. "Redox-Active Supramolecular Polymer Binders for Lithium–Sulfur Batteries That Adapt Their Transport Properties in Operando." Chemistry of Materials 28, no. 20: 7414-7421.