Solidifying Cathode–Electrolyte Interface for Lithium–Sulfur Batteries

Abstract

Lithium–sulfur (Li–S) batteries, with their distinct advantages in energy output, cost, and environmental benignancy, have been recognized as one of the most promising candidates for near‐future energy storage markets. However, the energy storage technology based on Li–S systems, even at the single cell level, is far from commercialization. The implementation of the technology is hindered by unstable electrochemistry at the electrode–electrolyte interface, especially the cathode–electrolyte interface. In cases where the cathode builds a solid–liquid interface with the electrolyte, strong interactions between discharge intermediates of S and solvent molecules of the liquid electrolyte lead to continuous loss of active S species from the cathode to the anode through an electrochemical shuttle process, and hampers the cycling performance of the battery. By solidifying the cathode–liquid interface, the polysulfide–solvent interaction is expected to be alleviated and the Li–S electrochemistry improved. In this Progress Report, the strategies to build a solidified cathode–electrolyte interface in liquid, quasi‐solid‐state and all‐solid‐state Li–S systems are summarized, and the fundamentals of charge transfer and chemical evolutions at the interface are discussed. With these discussions, the rational interfacial design of Li–S batteries is elucidated, toward optimal storage performance and operational durability.

Sulfophobic and Vacancy Design Enables Self‐Cleaning Electrodes for Efficient Desulfurization and Concurrent Hydrogen Evolution with Low Energy Consumption

“…[ 62 ] Interfacial properties between cathode materials and S 8 influence the battery properties. [ 63,64 ] Figure S30a–c shows the CV curves of NiS 2 , Ni, and carbon in a non‐aqueous solution containing 0.01 m Li 2 S 4 . We adopted a rotating disk electrode to maintain a stable transport condition for comparison.…”

Lithium Argyrodite as Solid Electrolyte and Cathode Precursor for Solid‐State Batteries with Long Cycle Life

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cathode materials into ASSBs could further increase the specific energy substantially. [11] However, the morphological, structural, and chemical changes during cycling are highly complex [12] and the cycling performance of ASSBs at room temperature (RT) with conversion-type cathode materials, such as S, FeS 2 , or Li 2 S, is not yet satisfactory. [13][14][15] Whereas liquid electrolyte can easily infiltrate the porous cathode composite to homogeneously contact active material particles and form a fast ion transport network, this is more difficult to achieve in ASSBs.

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A critical discussion on the analysis of buried interfaces in Li solid-state batteries. Ex situ and in situ/operando studies

“…76 Solid electrolytes have been proposed as a solution to this problem because they can act as physical barriers. 77 However, this work illustrates the incapacity of "solid electrolytes" with low melting temperatures to avoid polysulfide shuttling during cycling at moderate-high temperatures (55 °C -75 °C).…”