Supercooled liquid sulfur maintained in three-dimensional current collector for high-performance Li-S batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries face challenges due to the insulating nature of sulfur and lithium sulfide (Li2S), hindering electron/ion transfer kinetics.
• Solid-state phase transitions of sulfur and Li2S are rate-limiting steps in Li-S battery operation.
• Current collector material significantly influences sulfur species behavior and electrochemical performance.

Purpose of the Study:

• To visualize and understand sulfur growth mechanisms on different current collectors (Al, carbon, Ni).
• To investigate the impact of sulfur's physical state (solid vs. liquid) on Li-S battery performance.
• To design and evaluate a novel 3D Ni-based current collector for high-performance Li-S batteries.

Main Methods:

• In-situ visualization of sulfur deposition and growth on various current collectors.
• Electrochemical performance testing (reversible capacity, kinetics, cycling stability).
• Analysis of phase transition facilitation by the current collector material.

Main Results:

• Liquid sulfur generated on Ni current collectors exhibited superior reversible capacity, faster kinetics, and enhanced cycling life compared to solid sulfur.
• Nickel demonstrated a catalytic effect, facilitating the crucial Li2S decomposition phase transition.
• A 3D Ni-based current collector was successfully designed to control sulfur deposition and conversion.

Conclusions:

• The physical state of sulfur (solid vs. liquid) critically impacts Li-S battery performance.
• Nickel current collectors play a vital role in promoting liquid sulfur utilization and phase transitions.
• This research advances electrode design strategies for high-energy Li-S batteries by optimizing current collector properties.