Revamping Lithium–Sulfur Batteries for High Cell‐Level Energy Density by Synergistic Utilization of Polysulfide Additives and Artificial Solid‐Electrolyte Interphase Layers

Abstract

The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adma.202104246.Despite the high theoretical capacity of lithium-sulfur (Li-S) batteries, a high cell-level energy density and a long cycling life are barely achieved, mainly due to the large electrolyte-to-sulfur ratio, polysulfide (PS) shuttle causing the loss of active sulfur, and the formation of passivation layers on the Li anode. To raise the energy density, holding PS in the cathode has been the most popular approach. Still, it has failed, particularly, when the sulfur loading is high enough to have energy densities similar to those of commercial Li-ion batteries. Here, a practical approach of achieving high "cell-level" energy densities is attempted using lithium PS (LPS)-containing electrolytes instead of a pure electrolyte, reducing the electrolyte-to-sulfur ratio and PS diffusion out of the cathode due to concentration differences. Meanwhile, the persistent problems including PS passivation and Li dendrites are suppressed using Li 2 S-phobic artificial solid-electrolyte interphase (A-SEI) layers on Li metal. The synergistic effects from the LPS additives and A-SEI result in a superior cell-level volumetric energy density of 650 Wh L −1 as well as large cumulative energy densities considering cycling life. This approach provides an important stepping stone to realize commercial Li-S batteries rivaling the current Li-ion batteries.

High‐Performance All‐Solid‐State Batteries Enabled by Intimate Interfacial Contact Between the Cathode and Sulfide‐Based Solid Electrolytes

“…[22] However, high SEs content in the electrode induces low cell energy density and high fabrication costs. [23] Therefore, alternative solutions to address physical contact issues are essential for the development of ASSBs with high energy density. Typically, SEs coating on CAM particles via a solution process has been studied to create intimate physical contact.…”

Unraveling the Coupling Effect between Cathode and Anode toward Practical Lithium–Sulfur Batteries

“…The charge-transfer behavior can be tuned by several factors such as temperature, [12] catalysts, [13] the electroactive surface area of the electrode, [14] and additional electron pathways introduced by special structural design. [15,16] With the development of Li-S batteries entering practicality, regulating the mass and charge transfer of sulfur cathode will affect the delicate environment of electrochemical reactions, thus shedding greater influence on the anode. Bridging cathode mass/charge transfer and anode morphological evolution is therefore urgently required to deepen the understanding of the coupling between cathode and anode.…”

A separator coated with commercial LiFePO4 and conductive carbon for Li–S battery with good cycling performance

“…[20][21][22][23] Adding additives to the electrolyte can reduce the dissolution of polysuldes, and form a stable SEI on the lithium anodes, thus improving the electrochemical performance of Li-S batteries. [24][25][26] These studies were successful, but tailored preparation processes for functional-material structures oen lead to increased costs and are not conducive to the commercialization of Li-S batteries.…”