Interfacial chemistry-driven reaction dynamics and resultant microstructural evolution in lithium-based...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Understanding all-solid-state batteries (ASSBs) requires multi-length scale analysis.
• Microstructural evolution, including pore formation and contact loss, challenges ASSB studies.
• Chemical degradation at interfaces significantly impacts ASSB performance.

Purpose of the Study:

• To investigate the impact of chemical degradation on reaction behavior and microstructural evolution in Ni-rich cathode particles within sulfide-based ASSBs.
• To evaluate the role of lithium difluorophosphate (LiDFP) in suppressing chemical degradation.

Main Methods:

• Utilized a model system with LiNi0.6Co0.2Mn0.2O2 cathodes, Li-In alloy anodes, and a non-decomposable coating layer.
• Employed LiDFP to suppress interfacial chemical degradation.
• Analyzed reaction uniformity, mechanical degradation, pore formation, and tortuosity.

Main Results:

• Suppressing chemical degradation with LiDFP enhanced particle reaction uniformity and homogenized mechanical degradation, but increased pore formation and tortuosity.
• Uncontrolled chemical degradation led to significant reaction heterogeneity and non-uniform mechanical degradation with fewer pores and lower tortuosity.
• Coating layers are crucial for maintaining cathode surface contact and promoting lithium conduction.

Conclusions:

• Chemical degradation critically influences reaction and mechanical degradation heterogeneity in ASSBs.
• LiDFP effectively suppresses chemical degradation, impacting microstructural evolution.
• Findings emphasize the importance of interfacial engineering and protective coatings for ASSB performance.