Diagnosing and Correcting the Failure of the Solid‐State Polymer Electrolyte for Enhancing Solid‐State Lithium–Sulfur Batteries

Abstract

Solid‐state polymer electrolytes (SPEs) attract great interest in developing high‐performance yet reliable solid‐state batteries. However, understanding of the failure mechanism of the SPE and SPE‐based solid‐state batteries remains in its infancy, posing a great barrier to practical solid‐state batteries. Herein, the high accumulation and clogging of “dead” lithium polysulfides (LiPS) on the interface between the cathode and SPE with intrinsic diffusion limitation is identified as a critical failure cause of SPE‐based solid‐state Li–S batteries. It induces a poorly reversible chemical environment with retarded kinetics on the cathode–SPE interface and in bulk SPEs, starving the Li–S redox in solid‐state cells. This observation is different from the case in liquid electrolytes with free solvent and charge carriers, where LiPS dissolve but remain alive for electrochemical/chemical redox without interfacial clogging. Electrocatalysis demonstrates the feasibility of tailoring the chemical environment in diffusion‐restricted reaction media for reducing Li–S redox failure in the SPE. It enables Ah‐level solid‐state Li–S pouch cells with a high specific energy of 343 Wh kg−1 on the cell level. This work may shed new light on the understanding of the failure mechanism of SPE for bottom‐up improvement of solid‐state Li–S batteries.

High Energy Density Aqueous Zinc–Chalcogen (S, Se, Te) Batteries: Recent Progress, Challenges, and Perspective

“…Embedding active sulfur into conductive polymer by covalent bonds to yield sulfurized composites as the cathode is another demonstrated effective electrode engineering to realize excellent battery performance. [113][114][115] Unfortunately, the extremely accurate mechanism is not clear and urgently needs to be further probed. A pioneering work was carried out by Zhi and co-workers.…”

Solid-state polymer electrolytes in lithium batteries: latest progress and perspective

“…41,42 (5) In conjunction with in situ characterization of the lithium dendrite growth process, optimizing the interface composition and reducing the occurrence of side reactions. 43,44 The modification of SSEs made from polymers has achieved remarkable success thus far. This paper initially explores the mechanism behind the growth of lithium dendrites in these electrolytes.…”

“…41,42 (5) In conjunction with in situ characterization of the lithium dendrite growth process, optimizing the interface composition and reducing the occurrence of side reactions. 43,44…”

Heterojunction‐Accelerating Lithium Salt Dissociation in Polymer Solid Electrolytes

“…[7,8] However, the high cost of raw materials and inherent brittleness hinder the large-scale application of ceramic solid electrolytes, especially in the field of flexible energy storage devices. [9][10][11] In contrast, polymer solid electrolytes have attracted extensive attention owing to their low interface resistance, high flexibility, and low manufacturing costs. [12,13] Among the various polymers, a solid polymer electrolyte based on PEO is considered a promising choice for SSLMBs.…”