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Lithium–sulfur (Li–S) batteries are regarded as one of the most promising next-generation electrochemical cells. However, shuttling of lithium polysulfide intermediates and sluggish kinetics in random deposition of lithium sulfide (Li 2 S) have significantly degraded their capacity, rate and cycling performance. Herein, few-layered MoS 2 nanosheets enriched with sulfur vacancies are anchored inside hollow mesoporous carbon (MoS 2−x /HMC) via S–C bonding and proposed as a novel functional mediator for Li–S batteries. Ultrathin MoS 2 sheets with abundant sulfur vacancies have strong chemical affinity to polysulfides and in the meantime catalyze their fast redox conversion with enhanced reaction kinetics as proved by experimental observations and first-principles density functional theory (DFT) calculations. At a current density of 1C, the MoS 2−x /HMC-S composite cathode exhibits a high initial capacity of 945 mA h g −1 with a high retained capacity of 526 mA h g −1 and a coulombic efficiency of nearly 100% after 500 cycles. The present work sheds light on the design of novel functional electrodes for next-generation electrochemical cells based on a simple yet effective vacancy engineering strategy.
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Stable Lithium Sulfur Battery Based on In Situ Electrocatalytically Formed Li 2 S on Metallic MoS 2 –Carbon Cloth Support
Abstract A stable lean‐electrolyte operating lithium–sulfur (Li–S) battery based on a cathode of Li2S in situ electrocatalytically deposited from L2S8catholyte onto a support of metallic molybdenum disulfide (1T‐MoS2) on carbon cloth (CC) is created. The 1T‐MoS2significantly accelerates the conversion Li2S8catholyte to Li2S, chemically adsorbs lithium polysulfide (LiPSs) from solution, and suppresses crossover of the LiPSs to the anode. These experimental findings are explained by density functional theory calculations that show that 1T‐MoS2gives rise to strong adsorption of polysulfides on its surface and is electrocatalytic for the targeted reversible Li–S conversion reactions. The CC/1T‐MoS2electrode in a Li–S battery delivers an initial capacity of 1238 mAh g−1, with a low capacity fade of only 0.051% per cycle over 500 cycles at 0.5C. Even at a high sulfur loading (4.4 mg cm−2) and low electrolyte/S (E/S) ratio of 3.7 µL mg−1, the battery achieves an initial reversible capacity of 1176 mA h g−1at 0.5C, with 87% capacity retention after 160 cycles. The post 500 cycles Li metal opposing 1T‐MoS2is substantially smoother than the Li opposing CC, with XPS supporting the role of 1T‐MoS2in inhibiting LiPSs crossover.
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- Award ID(s):
- 1938833
- PAR ID:
- 10456443
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Small Methods
- Volume:
- 4
- Issue:
- 9
- ISSN:
- 2366-9608
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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