Highly Conductive Li-Excess Oxide to Facilitate Durable Interfaces in All-Solid-State Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• All-solid-state batteries (ASSBs) offer higher energy density and safety than lithium-ion batteries (LIBs) due to solid electrolytes.
• Interfacial side reactions between Ni-rich cathodes and sulfide solid electrolytes hinder ASSB commercialization by reducing reversibility and stability.
• Effective strategies are needed to mitigate these interfacial issues for practical ASSB applications.

Purpose of the Study:

• To develop a surface coating strategy for Ni-rich cathode materials to improve interfacial stability in ASSBs.
• To engineer LiAl5O8 with enhanced ionic conductivity and electrochemical stability for use as a protective layer.
• To evaluate the performance of ASSBs utilizing coated cathodes for potential electric vehicle applications.

Main Methods:

• Structural engineering of LiAl5O8 through optimized lithium concentrations and elemental substitution to create Li1+3xAl5-x-yByO8.
• Coating Ni-rich LiNi0.87Co0.10Mn0.03O2 cathodes with the tailored Li1+3xAl5-x-yByO8 surface layer.
• Fabricating and testing ASSBs with coated cathodes and Li6PS5Cl solid electrolytes to assess electrochemical performance.

Main Results:

• The engineered Li1+3xAl5-x-yByO8 coating significantly enhanced ionic conductivity and electrochemical stability.
• ASSBs with coated cathodes exhibited improved interfacial stability, suppressing detrimental side reactions.
• The coated ASSBs demonstrated enhanced reversibility and stable cycling performance compared to uncoated counterparts.

Conclusions:

• The tailored Li1+3xAl5-x-yByO8 surface coating effectively addresses interfacial challenges in ASSBs with Ni-rich cathodes.
• This surface engineering approach provides a practical pathway for developing high-performance and stable ASSBs.
• The findings support the advancement of ASSBs for demanding applications such as electric vehicles.