Coupling Stress Delocalization With Lithiation Homogenization: Omnidirectional Conformal Interface Integrating...

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Integrating silicon anodes with graphite is key for high-energy lithium-ion batteries (LIBs).
• Heterogeneous interfaces cause "stress singularity," leading to electrode failure and performance degradation.
• Existing strategies struggle to mitigate interfacial mechanical and kinetic issues.

Purpose of the Study:

• To develop novel omnidirectional conformal interface SiOC-graphite (OSiOCG) electrodes.
• To overcome the "stress singularity" effect at Si-graphite interfaces.
• To enhance the mechanical stability and electrochemical performance of LIBs.

Main Methods:

• Engineered conformal interlocking between silicon oxycarbide (SiOC) and graphite domains.
• Developed OSiOCG electrodes with an omnidirectional conformal interface.
• Investigated mechanical stress dissipation and electrochemical kinetics.

Main Results:

• OSiOCG electrodes effectively dissipated interfacial "stress singularity" by distributing force.
• Achieved 3D-percolation networks for electron/Li-ion transfer, mitigating polarization.
• Demonstrated stabilized cycling over 2000 cycles with <0.005% capacity decay per cycle.
• Showcased improved rate capability (19.3% at 4C, 12.8% at 10C) and pouch cell performance (88.3% retention at 4C).

Conclusions:

• The omnidirectional conformal interface effectively delocalizes interfacial stress in Si-based graphite composite electrodes.
• This approach significantly enhances the long-term reliability and practical performance of high-energy-density LIBs.
• Paves the way for commercialized, durable, high-performance LIBs.