Enhancing the Stability of Sulfur Cathodes in Li–S Cells via in Situ Formation of a Solid Electrolyte Layer

Lee, Jung Tae; Eom, KwangSup; Wu, Feixiang; Kim, Hyea; Lee, Jun Young; Zdyrko, Bogdan; Yushin, Gleb

doi:10.1021/acsenergylett.6b00163

Cited by 63 publications

(65 citation statements)

References 33 publications

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“…13,29,[37][38][39] In the present section we demonstrate the possibility of QSS type of sulfur cathodes operation both for carbon with pore width lower than 1 nm and for carbon having more than 50% of their pores wider than 1 nm.…”

Section: Sub-nano Confinement Of Sulfur In Carbon Matrix Is Not a Necmentioning

confidence: 66%

“…Voltage hysteresis and irreversible capacity observed during the first cycles are the result of side reactions of electrolyte solution components with Li 2 S n leading to SEI formation on the surface of S/C composite electrodes, what prevents further irreversible reactions. This scenario was observed also for porous carbons with pores size up to 2-3 nm 29,38,39 which can accommodate not only S 2-4 , but also S 5-8 and sulfur molecules S n (n > 8). Hence, the small molecules concept is not necessary for the explanation of QSS behavior of S/C cathodes.…”

mentioning

confidence: 62%

“…15,45 In most cases this mechanism is observed for composite S/C electrodes with very narrow micropores which width is lower than 1 nm, [14][15][16]19,20,22,23,28,40 but in some cases this type of operation was described also for larger pore size. 13,29,[37][38][39] Several explanations for this single-plateau behavior can be found in the literature.1. The formation of special complexes of the sulfur embedded in the fine pores with carbon or surface-bound oxygen.…”

mentioning

confidence: 99%

“…The realization of quasi-solid-state reaction is governed by the formation of solid electrolyte interphase (SEI) on the surface of sulfur cathodes during the initial discharge. 29,[38][39][40] Surface films when formed, force desolvation of Li ions that migrate through them, and hence, induce possible quasi-solid-state operation of the cells. Voltage hysteresis and irreversible capacity observed during the first cycles are the result of side reactions of electrolyte solution components with Li 2 S n leading to SEI formation on the surface of S/C composite electrodes, what prevents further irreversible reactions.…”

mentioning

confidence: 99%

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Review—On the Mechanism of Quasi-Solid-State Lithiation of Sulfur Encapsulated in Microporous Carbons: Is the Existence of Small Sulfur Molecules Necessary?

Markevich

Salitra

Talyosef

et al. 2016

J. Electrochem. Soc.

102

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In this work we analyzed the phenomenon of quasi solid state (QSS) lithiation of sulfur-carbon (S/C) composite electrodes with sulfur confined in the micropores of carbon matrices based on our recent studies and data published in literature. We demonstrated that the existence of sulfur in the form of small molecules is not a necessary condition for the realization of QSS mechanism. QSS operation behavior was demonstrated both for carbons with small up to 1nm micropores and for carbons with larger pore size up to 2-3 nm. A key role in the operation of S/C electrodes via a QSS mechanism plays surface electrolyte interphase (SEI) which is formed on the surface of S/C composite during the initial discharge. The formation of SEI was supported by X-ray photoelectron spectroscopy and by scanning electron microscopy. Small pore size (up to 1 nm) of the carbon matrices has a positive effect on the cycling of S/C electrodes. A superior cycling performance for more than 3500 charge-discharge cycles was demonstrated for S/C composite electrodes based on carbons synthesized by carbonization of polyvinylidene dichloride (PVDC) resin. In recent years lithium-sulfur batteries have been the subject of very intensive research due to the high theoretical specific capacity of sulfur cathodes (1672 mA h g −1 ) which is an order of magnitude higher than that of lithiated transition-metal oxides and phosphates cathode materials used in commercial Li-ion batteries (140-200 mA h g −1 ). [1][2][3][4][5][6] This high capacity relates to the ability of sulfur atoms to accept two electrons resulting in the conversion of elemental sulfur to lithium sulfide (Li 2 S). Furthermore, sulfur is naturally abundant, environmentally friendly and relatively cheap.Due to the low electrical conductivity of elementary sulfur the addition of conductive additives or the use of conductive host materials it is necessary to ensure good performance of sulfur electrodes. Besides, during the discharge process elemental sulfur S 8 accepts electrons to give a chain of electroactive Li-polysulfides (Fig. 1a). The long-chain polysulfides Li 2 S n (4 ≤ n ≤ 8) are soluble in commonly used ethereal solvents and diffuse freely throughout the cell to the anode side where they are chemically reduced. This phenomenon known as the shuttle effect presents one of the main problems of Li-S cells. 7 The shuttle reactions prevent the possibility of extracting the full capacity of sulfur cathodes and lead to low Coulombic efficiency. Encapsulation of sulfur within activated carbons with high pores volume is one of the most effective approaches to mitigate the detrimental shuttle mechanism and stabilize composite sulfur cathodes during prolong cycling. 8-10The typical cyclic voltammetry and galvanostatic charge-discharge curves of the Li-S cell with C/S encapsulated cathode are shown in Fig. 1a. Two peaks observed in the cathodic voltammetric response of sulfur electrodes correspond to two plateaus observed in the voltage profiles of the discharge processes of these cathodes upon ...

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Section: Sub-nano Confinement Of Sulfur In Carbon Matrix Is Not a Necmentioning

confidence: 66%

mentioning

confidence: 62%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Review—On the Mechanism of Quasi-Solid-State Lithiation of Sulfur Encapsulated in Microporous Carbons: Is the Existence of Small Sulfur Molecules Necessary?

Markevich

Salitra

Talyosef

et al. 2016

J. Electrochem. Soc.

102

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“…A Li ion conducting layer can be formed on the cathode by the highly concentrated electrolyte, acting as a barrier to inhibit LiPSs transport. 97 The other is that it remarkably suppresses the Li dendrite growth and shape change of the metallic Li anode. When the highly concentrated electrolyte is adopted in the Li−S battery, a near 100% Coulombic efficiency and long cycling stability are achieved.…”

Section: Metal Protection In Li−s Batteriesmentioning

confidence: 99%

Review—Li Metal Anode in Working Lithium-Sulfur Batteries

Cheng

Huang

Zhang

2017

J. Electrochem. Soc.

251

170

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Due to the high theoretical energy density of 2600 Wh kg −1 , lithium-sulfur batteries are strongly regarded as the promising nextgeneration energy storage devices. However, the practical applications of lithium-sulfur batteries are challenged by several obstacles, including the low sulfur utilization and poor lifespan, which are partly attributed to the shuttle of lithium polysulfides and lithium dendrite growth in working lithium-sulfur batteries. Suppressing lithium dendrite growth is a necessary step not only for a safe and efficient Li metal anode, but also for a high capacity cell with a high Coulombic efficiency. Herein we review the lithium metal anode protection in a polysulfide-rich environment, relative to most reviews on lithium metal anode without considering the effect of lithium polysulfides in lithium metal batteries. Firstly, the importance and dilemma of Li metal anode issues in lithium-sulfur batteries are underscored, aiming to arouse the attentions to Li metal anode protection. Specific attentions are paid to the surface chemistry of Li metal anode in a polysulfide-rich lithium-sulfur battery. Next, the proposed strategies to stabilize solid electrolyte interface and protect Li metal anode are included. Finally, a general conclusion and a perspective on the current limitations, as well as recommended future research directions of Li metal anode in lithium-sulfur batteries are presented. The ever-increasing requirement for efficient and economic energy storage technologies has triggered the continued research into advanced battery systems.1 Lithium ion batteries, based on the lithium intercalation chemistry, have dominated the battery market since their commercial application in the 1990s.2 However, conventional lithium ion batteries are very expensive and their energy densities (theoretically, 350 − 500 Wh kg −1 , practically, 100 − 250 Wh kg −1 ) seem insufficient for long-range electrical vehicles and high-end portable electronics. These emerging demands have energized the evolution of other alternative rechargeable batteries with higher energy density and longer lifespan.3 Lithium−sulfur (Li−S) battery, a 'beyond Li-ion' technology, has drawn extensive attentions due to its high specific capacity (1675 mAh g −1 ) and energy density (2600 Wh kg −1 ). 4-6The greater energy storage ability of Li−S batteries is realized through the phase-transformation electrochemistry based on elemental sulfur cathode and metallic lithium anode [S 8 + 16Li ↔ 8Li 2 S], 7,8 which is fundamentally different from current transition metal-based cathodes and graphite-based anodes in Li-ion batteries.The conversion chemistry in a Li−S cell offers not only significant advantages as mentioned above, but also some critical challenges, such as the low conductivity of sulfur and lithium sulfide, the huge volumetric change from sulfur (71 mol L −1 ) to lithium sulfide (36 mol L −1 ), and the shuttle of long-chain polysulfide intermediates during discharge/charge cycling.9-12 Therefore, a composite cathode with sulfur in ...

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Development and Challenges of Functional Electrolytes for High‐Performance Lithium–Sulfur Batteries

Wang

Chen

et al. 2018

Adv Funct Materials

151

110

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Lithium-sulfur (Li-S) batteries, as one of the most important candidates of next-generation batteries, are famous for high energy density, low cost, and environmental friendly benignity. However, issues originating from polysulfide shuttle of common liquid electrolytes (e.g., capacity fade, poor cycle life, and safe issue) have hindered the applications of Li-S batteries in various occasions. This review summarizes the main efforts in the electrolytes of Li-S batteries, including liquid, solid state, and hybrid electrolyte systems. The development of functional electrolytes for Li-S batteries is hopeful to alleviate the problems Li-S batteries faced today. The liquid electrolytes circumvent the polysulfide shuttle and the resultant problems by utilizing different functional solvents, lithium salts, and additives. Solid-state electrolytes as promising electrolytes are optimized to enhance the ionic conductivity at room temperature and decrease the interfacial resistance. Hybrid electrolytes that consist of two or more single electrolytes may be considered as unique categories because they have the potential advantages than the single electrolyte systems. Challenges and perspectives of Li-S electrolytes are also proposed based on the requirement for high-performance Li-S batteries.be reduced to short-chain ones, which subsequently migrate back to cathode and are reoxidized to long-chain lithium polysulfide intermediates. This endless movement and shuttle of polysulfides between cathode and anode is generally called as polysulfide shuttle. During cycling, the shuttle effect of polysulfides continuously occurs and results in lower Coulombic efficiency and anode corrosion. [3a,4,5] c) Safety issues: the electrolyte solvents may be not stable when the high reactivity of lithium metal and the soluble polysulfides are present, which results in the gradual depletion of solvents and the gas expansion of batteries. [6] High flammable organic solvents increase safety hazard, when used under high-temperature conditions. [7] Moreover, the growth of lithium dendrites can potentially penetrate the separator, which leads to internal short circuits of batteries and serious safety issues. [8] In order to overcome the issues mentioned above and improve battery performance, some strategies have been examined, including the design of sulfur cathodes, [4,9] the protection of lithium anode, [10] and the optimization of electrolytes. [11] The electrolyte between cathode and anode is a crucial component as it affects the lithium-ion transport during the cycling process, which in part determines the batteries performance. [12] Electrolyte development is time consuming because it requires high-throughput experiment but is indispensable. Some works have therefore focused on the development of functional electrolyte in the last several years. Different roads lead to the same thing that usable electrolytes should possess many characters, such as high ionic transport, low viscosity, good chemical and electrochemical stability, nonflammab...

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Enhancing the Stability of Sulfur Cathodes in Li–S Cells via in Situ Formation of a Solid Electrolyte Layer

Cited by 63 publications

References 33 publications

Review—On the Mechanism of Quasi-Solid-State Lithiation of Sulfur Encapsulated in Microporous Carbons: Is the Existence of Small Sulfur Molecules Necessary?

Review—On the Mechanism of Quasi-Solid-State Lithiation of Sulfur Encapsulated in Microporous Carbons: Is the Existence of Small Sulfur Molecules Necessary?

Review—Li Metal Anode in Working Lithium-Sulfur Batteries

Development and Challenges of Functional Electrolytes for High‐Performance Lithium–Sulfur Batteries

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