Stable and Flexible Sulfide Composite Electrolyte for High-Performance Solid-State Lithium Batteries

Yang Li; William Arnold; Arjun Thapa; Jacek B Jasinski; Gamini Sumanasekera; Mahendra Sunkara; Thad Druffel; Hui Wang

doi:10.1021/acsami.0c08261

Stable and Flexible Sulfide Composite Electrolyte for High-Performance Solid-State Lithium Batteries

ACS Appl Mater Interfaces. 2020 Sep 23;12(38):42653-42659. doi: 10.1021/acsami.0c08261. Epub 2020 Sep 9.

Authors

Yang Li¹, William Arnold², Arjun Thapa¹, Jacek B Jasinski¹, Gamini Sumanasekera^{1

3}, Mahendra Sunkara^{1

4}, Thad Druffel¹, Hui Wang^{1

2}

Affiliations

¹ Conn Center for Renewable Energy Research, University of Louisville, Louisville, Kentucky 40292, United States.
² Department of Mechanical Engineering, University of Louisville, Louisville, Kentucky 40292, United States.
³ Department of Physics & Astronomy, University of Louisville, Louisville, Kentucky 40208, United States.
⁴ Department of Chemical Engineering, University of Louisville, Louisville, Kentucky 40292, United States.

PMID: 32845121
DOI: 10.1021/acsami.0c08261

Abstract

Sulfide-based lithium (Li)-ion conductors represent one of the most popular solid electrolytes (SEs) for solid-state Li metal batteries (SSLMBs) with high safety. However, the commercial application of sulfide SEs is significantly limited by their chemical instability in air and electrochemical instability with electrode materials (metallic Li anode and oxide cathodes). To address these difficulties, here, we design and successfully demonstrate a novel sulfide-incorporated composite electrolyte (SCE) through the combination of inorganic sulfide Li argyrodite (Li₇PS₆) with poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP) polymer. In this composite structure, Li₇PS₆ is embedded in PVDF-HFP polymer matrix, making the SCE flexible and air-stable and achieve great chemical and electrochemical stability. Meanwhile, the presence of sulfide facilitates Li-ion transport in SCE, leading to a superior room-temperature ionic conductivity of 1.1 × 10^-4 S cm^-1. Using the SCE with enhanced stability while maintaining high conductivity, Li||Li symmetric cells achieved stable cycling up to 1000 h at 0.2 mA cm^-2. In addition, LiFePO₄ (LFP)||SCE||Li cells can deliver an impressive specific capacity of 160 mAh g^-1 over 150 cycles. These features indicate that Li₇PS₆/PVDF-HFP SCE is a promising candidate to contribute to the practical development of SSLMBs.

Keywords: PVDF-HFP; composite electrolyte; lithium argyrodites; lithium battery; sulfide solid electrolyte.