A Self‐Limited Free‐Standing Sulfide Electrolyte Thin Film for All‐Solid‐State Lithium Metal Batteries

Abstract

All‐solid‐state (ASS) lithium metal batteries (LMBs) are considered the most promising next‐generation batteries due to their superior safety and high projected energy density. To access the practically desired high energy density of ASS LMBs, an ultrathin solid‐state electrolyte (SSE) film with fast ion‐transport capability presents as an irreplaceable component to reduce the proportion of inactive materials in ASS batteries. In this contribution, an ultrathin (60 µm), flexible, and free‐standing argyrodite (Li6PS5Cl) SSE film is designed through a self‐limited strategy. A chemically compatible cellulose membrane is employed as the self‐limiting skeleton that not only defined the thinness of the sulfide SSE film but also strengthened its mechanical properties. The ionic conductivity of the SSE film reaches up to 6.3 × 10−3 S cm−1 at room temperature, enabling rapid lithium‐ion transportation. The self‐limited SSE thin films are evaluated in various ASS LMBs with different types of cathode (sulfur and lithium titanate) and anode materials (lithium and lithium‐indium alloy) at both mold‐cell and pouch‐cell levels, demonstrating a stable performance and high‐rate capability. This study provides a general strategy for the rational design of an SSE thin film towards high‐energy‐density ASS batteries.

Challenges, interface engineering, and processing strategies toward practical sulfide‐based all‐solid‐state lithium batteries

“…Meanwhile, some properties of the templates, such as thermal stability, chemical stability, and mechanical properties (e.g., strength and flexibility), can be inherited by the SE membranes to a certain extent. 383 For example, Kim et al 371 reported a scalable preparation protocol for thin, flexible, and thermally stable sulfide SE membranes, fabricated through infiltrating solutionprocessable Li 6 PS 5 Cl 0.5 Br 0.5 into porous PI scaffold (Figure 15F). In this configuration, the high thermal stability of PI enables the available heat-treatment temperature up to 400 C and thereby endows Li 6 PS 5 Cl 0.5 Br 0.5 with high crystallinity and enhanced Li + conductivity (2.0 mS cm À1 ).…”

“…Naturally, by means of direct infiltrating SE solution into the templates enable sulfides to distribute homogeneously and fill the pores of templates. Meanwhile, some properties of the templates, such as thermal stability, chemical stability, and mechanical properties (e.g., strength and flexibility), can be inherited by the SE membranes to a certain extent 383 . For example, Kim et al 371 reported a scalable preparation protocol for thin, flexible, and thermally stable sulfide SE membranes, fabricated through infiltrating solution‐processable Li 6 PS 5 Cl 0.5 Br 0.5 into porous PI scaffold (Figure 15F).…”

Recent progress of sulfide electrolytes for all-solid-state lithium batteries

“…Cycling stability of Li 6 PS 5 Cl electrolyte against Li metal was improved after adding poly(1,1difluoroethylene) (PVDF), which was proved by longer cycling life and lower polarization of symmetric cell using the composite membrane as the interlayer in the galvanostatic tests at a current density of 0.2 mA cm -2 . Liu et al [184] coated a 5 nm thick homogeneous polydopamine layer on Li 6 PS 5 Cl electrolyte and prepared a 35 μm thick free-standing electrolyte film by cold pressing the coated electrolytes. Zhu et al [185] designed a free-standing sulfide film through a self-limited strategy.…”

Recent Advances and Perspectives in Lithium−Sulfur Pouch Cells

“…Sulfide-based solid electrolytes are easy to process, have high ionic conductivity, and have the lowest electronic conductivity at room temperature [75]. These characteristics allow them to be integrated into Li-S cells with limited volume and a soft interface contact.…”