Study of the discharge/charge process of lithium–sulfur batteries by electrochemical impedance spectroscopy

Qiu, Xiangyun; Hua, Qingsong; Zheng, Lili; Dai, Zuoqiang

doi:10.1039/c9ra10527a

Cited by 66 publications

(59 citation statements)

References 35 publications

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“…The Nyquist plots of all the cells consisted of a semicircle in the high‐ and medium‐frequency regime and an inclined line in the low‐frequency regime. The EIS analyses indicate that the charge‐transfer resistance ( R ct ), [ 20 ] represented by the semi‐circle, decreases as the amount of LiNO 3 increases, to 77.5, 56.5, and 50.3 Ω for the DMI‐LNO‐0 m , 0.2 m , and 0.5 m cells, respectively, once again pointing to the stabilization of the Li metal interface by the addition of LiNO 3 .…”

Section: Figurementioning

confidence: 99%

New High Donor Electrolyte for Lithium–Sulfur Batteries

et al. 2020

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The attainable specific energy of Li-S cells is largely affected by the electrolyteto-sulfur (E/S) ratio, with a low value [5] thereof being prerequisite to achieve a competitive energy density for a practical cell. However, the most commonly used electrolyte, a mixture of 1,3-dioxolane (DOL) and 1,2-dimethoxyethane (DME) (i.e., v/v = 1:1), exhibits low Li 2 S 8 solubility of at most 0.7 m at room temperature. [6] This limited solubility constitutes an obstacle in the way of the full-depth utilization of sulfur under so-called lean electrolyte conditions. Although it could be overcome by using a large amount of electrolyte, this would severely impair the volumetric energy density. This notwithstanding, the DOL/DME system and its analogues served as standard electrolyte solvents in the early stages of investigation, because the stable environment they offer to Li metal anodes contributed greatly to enhancing the cycle life. Nevertheless, identifying electrolyte conditions that allow effective operation at low E/S ratios (i.e., below 2 μL electrolyte mg sulfur −1 in practice) is essential for practical cells. [7] Therefore, the development of alternative electrolyte solvents with high polysulfide solubility remains highly desirable. Electrolytes with a high Gutmann donor number, such as N,N-dimethyl acetamide (DMAc), [7a,8] dimethyl sulfoxide (DMSO), [6,7,9] N,N-dimethyl formamide (DMF), [10] and N-methyl-2-pyrrolidone (NMP) [9c] are good candidates for lean electrolyte conditions in Li-S batteries. High donicity affords an environment that promotes interaction with electrophilic cations, implying that the solvation of Li ions can facilitate the solubility of polysulfides. For example, high donor electrolytes were reported [6] to readily dissolve more than 1.6 m of Li 2 S 8. In the same line, the utilization of sulfur can be enhanced for the given amount of electrolyte introduced in the cell. Apart from the solvation capability, high donor electrolytes confer 3D morphology for the final discharging product, namely Li 2 S, contrary to low donor electrolytes that give rise to a 2D film-like morphology. The 3D morphology is beneficial in that it leaves the conductive electrode surface available for repeated dischargecharge over cycling without passivation. [11] In addition, high donor electrolytes activate reaction routes that involve S 3 •− species (Figure 1a), [8a,12] the availability of which represents diverse reaction pathways for discharge to further enhance the utilization of sulfur. Despite these remarkable advantages, high donor electrolytes are known to have a short cycle life mainly because of their catastrophic reactivity with the Li metal anode. [8a,11c] This problem was subsequently pinpointed by Gupta et al., [7a] who

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Section: Figurementioning

confidence: 99%

New High Donor Electrolyte for Lithium–Sulfur Batteries

et al. 2020

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“…Here, we postulate that the solvation effect and intermediate chemical dissolution of the catholyte could significantly deviate from the practical limits [20,33] . To this end, we implement electrochemical impedance spectroscopy (EIS), a non‐invasive technique capable of monitoring the state of charge/discharge and state of health of the battery [52,53] . In the NaS system, the chemical composition of the catholyte follows a sequential reversible change on electrochemical charge/discharge [8,53] .…”

Section: Resultsmentioning

confidence: 99%

“…[20,33] To this end, we implement electrochemical impedance spectroscopy (EIS), a non-invasive technique capable of monitoring the state of charge/discharge and state of health of the battery. [52,53] In the NaS system, the chemical composition of the catholyte follows a sequential reversible change on electrochemical charge/discharge. [8,53] The EIS data revealed that the catholyte contributes heavily to the ohmic resistance ( Figure S2 & equation S1).…”

Section: Approach To Implement the Revised Charge-discharge Cut-off Lmentioning

confidence: 99%

“…[52,53] In the NaS system, the chemical composition of the catholyte follows a sequential reversible change on electrochemical charge/discharge. [8,53] The EIS data revealed that the catholyte contributes heavily to the ohmic resistance ( Figure S2 & equation S1). [24,25] So, knowing the tendency in conductivity of the catholyte at its different chemical composition during electrochemical charging and interpreting it through the EIS spectra at different states of charge, we can identify an adequate cut-off endpoint.…”

Section: Approach To Implement the Revised Charge-discharge Cut-off Lmentioning

confidence: 99%

“…Extending the charging process beyond Na 2 S 8 will hamper the conductivity on account of the formation of the insulating S (S 8 ) phase. [53] Upon subsequent discharge, the conductivity decreases, signifying the electrochemical reduction of Na 2 S 8 to Na 2 S 5 and then to Na 2 S 4 . [54] A cell containing 0.5 M Na 2 S 5 in TEGDME is subjected to EIS measurements throughout periodic intermediate stages (labeled C 1 to C 5 ) of galvanostatic charging, as illustrated in (Figure 5b) until C 3 , in line with the conductivity data.…”

Section: Approach To Implement the Revised Charge-discharge Cut-off Lmentioning

confidence: 99%

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Operational Strategies to Improve the Performance and Long‐Term Cyclability of Intermediate Temperature Sodium‐Sulfur Batteries

Kandhasamy

Nikiforidis

Jongerden³

et al. 2021

ChemElectroChem

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Based on the preliminary investigation of the intermediate temperature sodium-sulfur (IT-NaS) battery (150°C), herein we advance this energy storage system, by retuning the catholyte formulation; namely i) concentration, ii) layer thickness, and iii) cutoff limits during galvanostatic charge-discharge cycling, lowering the operating temperature and improving cell design. The systematic implementation of these strategies boosted the cell performance significantly, delivering 112 mAh/g-sulfur, 90 % of its theoretical specific capacity (125 mAh/g-sulfur), and 50 deep reversible charge-discharge cycles with coulombic and round-trip energy efficiencies of 97 � 3 % and 73 � 4 %, respectively. Along with the stability and improvement of cycle life, this study demonstrates, for the first time, the practicality of the tubular IT-NaS technology at a temperature as low as 125°C.

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Multifunctional ZnCo₂O₄ Quantum Dots Encapsulated In Carbon Carrier for Anchoring/Catalyzing Polysulfides and Self‐Repairing Lithium Metal Anode in Lithium‐Sulfur Batteries

Liu

Yang

et al. 2021

Adv Funct Materials

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Lithium‐sulfur batteries have recently attracted academic/industrial attention due to the high theoretical energy density. However, the capacity decay mainly caused by the polysulfides shuttle effect and poor conductivity of sulfur. Herein, in situ growth of ZnCo2O4 quantum dots (ZCO‐QDs) embedded into the hollow carbon‐carrier sphere (HCS) to form the ZnCo2O4 quantum dots nanocapsule (ZCO‐QDs@HCS) as the multifunctional sulfur host is rationally demonstrated. Based on density‐functional theory calculations, in situ spectroscopic techniques, and electrochemical studies, the synergistic effects on anchoring/catalyzing polysulfide of the ZCO‐QDs@HCS composite in Li‐S batteries is investigated. Interestingly, the ZCO‐QDs@HCS also allows for the controlled release of ZCO‐QDs into the Li‐S electrolyte. Subsequently, it is first discovered that these diffused ZCO‐QDs can act as self‐repairing initiators to stabilize Li metal anodes via rebuilding the damaged solid electrolyte interphase and suppressing Li dendrites growth. With this concept, quantum dots‐based catalyst delivery systems is first constructed in a Li‐S battery, which is similar to the use of nanocarrier‐based drug delivery systems in cancer therapy. The Li‐S cells with the S@ZCO‐QDs@HCS cathode display significantly superior electrochemical performances with a high specific capacity (1350.5 mAh·g−1 at 0.1 C) and excellent cycling stability (capacity decay rate of 0.057% per cycle after 1000 cycles at 3.0 C).

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Study of the discharge/charge process of lithium–sulfur batteries by electrochemical impedance spectroscopy

Abstract: Schematic model for the electrochemical reaction mechanism of a sulfur electrode in the discharge process.

Cited by 66 publications

References 35 publications

New High Donor Electrolyte for Lithium–Sulfur Batteries

New High Donor Electrolyte for Lithium–Sulfur Batteries

Operational Strategies to Improve the Performance and Long‐Term Cyclability of Intermediate Temperature Sodium‐Sulfur Batteries

Multifunctional ZnCo₂O₄ Quantum Dots Encapsulated In Carbon Carrier for Anchoring/Catalyzing Polysulfides and Self‐Repairing Lithium Metal Anode in Lithium‐Sulfur Batteries

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Study of the discharge/charge process of lithium–sulfur batteries by electrochemical impedance spectroscopy

Abstract: Schematic model for the electrochemical reaction mechanism of a sulfur electrode in the discharge process.

Cited by 66 publications

References 35 publications

New High Donor Electrolyte for Lithium–Sulfur Batteries

New High Donor Electrolyte for Lithium–Sulfur Batteries

Operational Strategies to Improve the Performance and Long‐Term Cyclability of Intermediate Temperature Sodium‐Sulfur Batteries

Multifunctional ZnCo2O4 Quantum Dots Encapsulated In Carbon Carrier for Anchoring/Catalyzing Polysulfides and Self‐Repairing Lithium Metal Anode in Lithium‐Sulfur Batteries

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Product

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Multifunctional ZnCo₂O₄ Quantum Dots Encapsulated In Carbon Carrier for Anchoring/Catalyzing Polysulfides and Self‐Repairing Lithium Metal Anode in Lithium‐Sulfur Batteries