A Li ₂ S‐TiS ₂ ‐Electrolyte Composite for Stable Li ₂ S‐Based Lithium–Sulfur Batteries

Journal Article · Wed Jun 26 00:00:00 EDT 2019 · Advanced Energy Materials

DOI:https://doi.org/10.1002/aenm.201901397· OSTI ID:1529640

Chung, Sheng‐Heng ^[1]; Manthiram, Arumugam  ^[1]

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1. Materials Science and Engineering Program &, Texas Materials Institute The University of Texas at Austin Austin TX 78712 USA

Abstract Li ₂ S is a fully lithiated sulfur‐based cathode with a high theoretical capacity of 1166 mAh g ⁻¹ that can be coupled with lithium‐free anodes to develop high‐energy‐density lithium–sulfur batteries. Although various approaches have been pursued to obtain a high‐performance Li ₂ S cathode, there are still formidable challenges with it (e.g., low conductivity, high overpotential, and irreversible polysulfide diffusion) and associated fabrication processes (e.g., insufficient Li ₂ S, excess electrolyte, and low reversible capacity), which have prevented the realization of high electrochemical utilization and stability. Here, a new cathode design composed of a homogeneous Li ₂ S‐TiS ₂ ‐electrolyte composite that is prepared by a simple two‐step dry/wet‐mixing process is demonstrated, allowing the liquid electrolyte to wet the powder mixture consisting of insulating Li ₂ S and conductive TiS ₂ . The close‐contact, three‐phase boundary of this system improves the Li ₂ S‐activation efficiency and provides fast redox‐reaction kinetics, enabling the Li ₂ S‐TiS ₂ ‐electrolyte cathode to attain stable cyclability at C/7 to C/3 rates, superior long‐term cyclability over 500 cycles, and promising high‐rate performance up to 1C rate. More importantly, this improved performance results from a cell design attaining a high Li ₂ S loading of 6 mg cm ⁻² , a high Li ₂ S content of 75 wt%, and a low electrolyte/Li ₂ S ratio of 6.

• Sponsoring Organization: USDOE
• Grant/Contract Number: DE‐SC0005397
• OSTI ID: 1529640
• Journal Information: Advanced Energy Materials, Journal Name: Advanced Energy Materials Vol. 9 Journal Issue: 30; ISSN 1614-6832
• Publisher: Wiley Blackwell (John Wiley & Sons)
• Country of Publication: Germany
• Language: English