# Revealing the Hidden Electrochemical Pathway for Cathode Electrolyte Interface Formation in Lithium–Sulfur Batteries with Carbonate-Based Electrolytes

## TL;DR

This paper explores how microporous carbons and carbonate-based electrolytes improve lithium-sulfur battery performance by forming a stable interface.

## Contribution

A novel electrochemical nucleophilic mechanism for CEI formation in carbonate-based Li–S batteries is proposed.

## Key findings

- A CEI composed of LiF forms in microporous carbons, sealing pores and stabilizing the system.
- Higher sulfur content in micropores enhances cycling stability in carbonate-based systems.
- Wider pores can be used without compromising performance due to the CEI formation.

## Abstract

This study investigates the role of microporous carbons
and carbonate-based
electrolytes in addressing challenges related to polysulfides dissolution
and electrolyte compatibility in lithium–sulfur (Li–S)
batteries. By employing microporous carbons and varying the sulfur
content, we investigate the formation of the cathode-electrolyte interphase
(CEI) during the first discharge process. We propose an electrochemical
nucleophilic mechanism for the formation of the CEI involving polysulfides
and solvent molecules in the confined small pores of the cathode.
This interphase, primarily composed of LiF, effectively seals the
carbon pores, preventing further solvent intrusion and stabilizing
the system. Furthermore, it allows the use of wider pores without
compromising the system. Our findings reveal that an increased sulfur
content within the micropores enhances cycling stability, contradicting
trends observed in ether-based systems. These insights highlight the
potential of designing Li–S systems with optimized pore structures
and electrolyte compositions to achieve greater stability and capacity
retention, marking a significant step forward in the development of
practical Li–S batteries.