Locking Cascade Reaction Path of Bulk Degradation Achieves Stable Unmodified Solid Electrolyte

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Solid-state batteries offer safety advantages but suffer from electrolyte degradation.
• The exact mechanisms of electrolyte degradation, particularly cathode-induced effects, remain unclear.
• Existing research often overlooks bulk decomposition, focusing primarily on interface phenomena.

Purpose of the Study:

• To elucidate the degradation mechanism of solid electrolytes influenced by cathode materials.
• To investigate the role of bulk decomposition in solid-state battery performance decline.
• To develop strategies for mitigating electrolyte degradation and enhancing battery longevity.

Main Methods:

• Investigated parasitic reactions between cathode and solid electrolyte materials.
• Analyzed electrolyte decomposition pathways using advanced characterization techniques.
• Engineered a Ni-rich cathode with a dissolution-retardant active structure.
• Performed long-term cycling tests to evaluate electrochemical performance and stability.

Main Results:

• Discovered that bulk decomposition, triggered by acidic species (HTFSI), is a primary degradation pathway.
• Identified a cascade reaction mechanism involving Ni dissolution and electrolyte decomposition.
• The designed dissolution-retardant electrode structure effectively suppressed bulk cascade reactions.
• Achieved 84% capacity retention after 2000 cycles at 2C/4.3 V, demonstrating significant improvement.

Conclusions:

• Electrolyte degradation in solid-state batteries is significantly influenced by bulk decomposition initiated by acidic byproducts.
• Mitigating bulk cascade reactions through electrode design is crucial for long-term battery stability.
• The developed electrode strategy offers a promising approach for next-generation high-energy, long-life solid-state batteries.