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

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.

Phase‐Transition Interlayer Enables High‐Performance Solid‐State Sodium Batteries with Sulfide Solid Electrolyte

“…Meanwhile, evident NaF and −CF x can be detected from the spectra of F 1s, which come from the decomposition of TFSI − in the interlayer. [ 43 ] In addition, the S 2p spectrum for pristine Na 3 SbS 4 SE powder can be fitted into SbS and SbSNa bonds, respectively. The Sb 3d spectrum shows a single doublet that corresponding to the SbS bond from the SbS 4 3− tetrahedron (Figure S5, Supporting Information).…”

Progress in thermal stability of all‐solid‐state‐Li‐ion‐batteries

“…Recently, sulfide SE fillers have also been investigated in the polymer SE systems. For example, Li et al 52 added Li 6 PS 5 Cl into PVDF‐HFP/LiTFSI and observed a small increase in T dec (lower than pure polymer), which was attributed to the modified ratio of crystalline to amorphous region. Zhao et al 53 also investigated the effect of adding LGPS on the thermal stability of the polymer SE system, showing decreased T m and T g .…”

“…(B) Comparison between Celgard separator and polyethylene oxide (PEO)/poly(vinylidene fluoride) (PVDF) + Li 6.75 La 3 Zr 1.75 Ta 0.25 O 12 (LLZO). Reproduced with permission from Reference 52. Copyright 2019, Springer Nature.…”

Air‐stable inorganic solid‐state electrolytes for high energy density lithium batteries: Challenges, strategies, and prospects

“…A new sulfide-incorporated composite electrolyte was designed with sulfide argyrodite Li 7 PS 6 and organic poly(vinylidenefluoride-co-hexafluoropropylene) (PVDF-HFP). 105 Li 7 PS 6 combined with PVDF-HFP showed good air and electrochemical stability. LiFePO 4 (LFP)jjLi 7 P-S 6 @PVDF-HFPjjLi cells reached an excellent specific capacity of 160 mAh g À1 over 150 cycles.…”