Low Temperature Epitaxial LiMn₂O₄ Cathodes Enabled by NiCo₂O₄ Current Collector for High-Performance Microbatteries

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Epitaxial cathodes are crucial for understanding ion transport and degradation in lithium-ion microbatteries.
• Current high-temperature growth methods (>600 °C) limit manufacturing and scalability for CMOS-compatible devices.
• Low-temperature (<450 °C) fabrication is essential for integrating microbatteries into flexible electronics and MedTech.

Purpose of the Study:

• To investigate the structural and electrochemical properties of epitaxial LiMn2O4 (LMO) thin films.
• To develop a low-temperature (<450 °C) fabrication process for LMO cathodes.
• To evaluate the performance and stability of LMO films on a new NiCo2O4 (NCO) current collector.

Main Methods:

• Epitaxial growth of LiMn2O4 thin films on NiCo2O4 current collectors at 360 °C.
• Structural characterization of the thin films.
• Electrochemical cycling to assess capacity, stability, and redox behavior.

Main Results:

• Successful low-temperature epitaxial growth of LMO films on NCO at 360 °C, ~200 °C lower than previous methods.
• Achieved discharge capacity exceeding 100 mAh g-1 over approximately 6000 cycles.
• Demonstrated long-term electrochemical stability and distinct LMO redox signatures, confirming NCO collector performance.

Conclusions:

• A viable low-temperature route for fabricating high-performance epitaxial LMO cathodes for microbatteries is established.
• The novel NCO current collector enables stable cycling at reduced temperatures, facilitating CMOS compatibility.
• This work paves the way for advanced, miniaturized lithium-ion microbatteries for IoT, flexible electronics, and MedTech.