Sol-Gel-Derived Ge-Substituted LLZO Ceramic Coatings on Lithium-Rich Layered Oxide Cathodes for Improved Interfacial...

Area of Science:

• Materials Science
• Electrochemistry
• Ceramic Engineering

Background:

• Gel-based routes, like sol-gel, are effective for creating functional ceramics with controlled properties.
• Lithium-rich manganese-based layered oxides (LMLOs) are promising cathode materials but suffer from interfacial instability.

Purpose of the Study:

• To develop a Ge-substituted garnet-type Li7La3Zr2O12 (Ge-LLZO) ceramic coating on LMLO cathode particles using a citrate-assisted sol-gel method.
• To investigate the impact of the Ge-LLZO coating on the interfacial properties and electrochemical performance of LMLO cathodes.

Main Methods:

• Citrate-assisted sol-gel coating to deposit Ge-LLZO precursor on LMLO particles.
• Drying and thermal conversion to form the ceramic coating.
• Structural and surface analyses (FE-SEM/EDS, XPS, FE-TEM, XRD) and electrochemical testing (impedance, rate capability).

Main Results:

• Successful formation of Ge-LLZO coating on LMLO particles, preserving the LMLO host structure.
• Coating influenced interfacial kinetics and resistance evolution, as shown by electrochemical tests.
• Coated LMLO demonstrated reduced cycling damage and improved capacity retention under harsh conditions compared to bare LMLO.

Conclusions:

• Gel-assisted deposition and conversion effectively create Ge-LLZO surface coatings on LMLO cathodes.
• The Ge-LLZO coating modulates interfacial kinetics and resistance, enhancing cycling stability.
• Further optimization is needed for long-term stability, but the approach shows promise for advanced batteries.