Decoupling Parasitic Reactions at the Positive Electrode Interfaces in Argyrodite-Based Systems

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state batteries (ASSBs) are crucial for electric vehicles, but interface degradation limits their performance.
• Understanding degradation mechanisms at the solid electrolyte (SE)/electrode interface is vital for improving ASSB autonomy and charging speed.

Purpose of the Study:

• To deeply investigate degradation reactions in Li6PS5Cl-based solid-state batteries.
• To decouple and analyze the effects of NMC/SE and VGCF/SE reactions under various operating conditions.
• To elucidate the impact of carbon additives and propose mitigation strategies.

Main Methods:

• Combined resistance monitoring and electrochemical impedance spectroscopy.
• Systematic investigation under varied temperatures, C-rates, and voltage windows.
• Analysis of different active materials and the presence/absence of carbon additives.

Main Results:

• Successfully decoupled two distinct degradation reactions (NMC/SE and VGCF/SE) with potential-dependent behavior.
• Disclosed the detrimental effects of carbon additives on initial cycling, power performance, and long-term capacity retention.
• Demonstrated that a coating layer on NMC particles mitigates high-potential interactions and capacity loss.

Conclusions:

• Carbon additives negatively impact ASSB performance and capacity retention.
• Eliminating carbon additives and employing protective coatings on electrode materials are promising strategies for enhancing ASSB stability.
• Findings provide insights for designing high-performing solid-state batteries.