Insight into sulfur reactions in Li-S batteries
Rui Xu1, Ilias Belharouak, Xiaofeng Zhang
1Chemical Sciences and Engineering Division, Argonne National Laboratory , 9700 South Cass Avenue, Argonne, Illinois 60439, United States.
ACS Applied Materials & Interfaces
|November 27, 2014
Summary
Understanding lithium-sulfur battery chemistry is key for high capacity. This study probes sulfur reduction species, revealing lithium sulfide crust formation that limits performance.
Area of Science:
- Electrochemistry
- Materials Science
- Battery Technology
Background:
- Developing high-capacity lithium-sulfur (Li-S) batteries is crucial for next-generation energy storage.
- Controlling sulfur reduction species (Li2Sx, 1 ≤ x ≤ 8) is essential for practical Li-S cell performance.
- Probing intermediates and products of Li-S redox reactions remains a significant challenge due to methodological limitations.
Purpose of the Study:
- To elucidate the mechanism of Li-S redox reactions.
- To characterize the properties of lithium polysulfides (Li2Sx) and lithium sulfide (Li2S).
- To identify factors contributing to capacity fade in Li-S cells.
Main Methods:
- Utilized various ex situ and in situ techniques for comprehensive analysis.
- Employed synchrotron high-energy X-ray diffraction (XRD) for solid deposit characterization.
- Conducted in situ transmission electron microscopy (TEM) and electrochemical impedance spectroscopy (EIS).
Main Results:
- Synchrotron XRD suggested the formation of novel lithium polysulfide crystallite phases.
- Observed polyhedral lithium sulfide (Li2S) crystallites in cells with conventional and polysulfide electrolytes.
- In situ TEM revealed preferential lithium diffusion to the sulfur surface, forming a Li2S crust during discharge.
Conclusions:
- The formation of a Li2S crust on the sulfur surface is identified as a potential cause of capacity fade.
- Characterization of sulfur species provides a baseline for improving Li-S battery performance.
- Findings guide future research for controlling sulfur species and achieving theoretical capacity in Li-S batteries.
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