Low-LUMO Orotic Acid Enables Li₃N-Embeded Solid Electrolyte Interphase for Stable All-Solid-State Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Science

Background:

• Biomacromolecules offer sustainable solutions for polymer electrolytes but their complexity hinders understanding.
• Challenges in polymer electrolytes include low ionic conductivity and interfacial instability.
• Small biomolecules can mimic functional groups of biomacromolecules for improved performance.

Purpose of the Study:

• To investigate the use of small biomolecules as effective fillers in polymer electrolytes.
• To elucidate the mechanism by which orotic acid (OA) enhances lithium (Li) ion conductivity and interfacial stability.
• To evaluate the performance of OA-modified polymer electrolytes in lithium-ion batteries.

Main Methods:

• Incorporation of orotic acid (OA) into polyethylene oxide (PEO) polymer electrolyte matrix.
• Electrochemical characterization including ionic conductivity measurements.
• Analysis of the solid electrolyte interphase (SEI) formation using techniques sensitive to Li3N.
• Battery cycling performance evaluation in Li||LiFePO4 cells.

Main Results:

• Orotic acid (OA) enhanced Li ion conductivity by facilitating LiTFSI dissociation without affecting PEO crystallinity.
• The amide-rich structure of OA led to the formation of a Li3N-embedded solid electrolyte interphase.
• OA-optimized PEO electrolytes demonstrated excellent cycling stability: 95.2% capacity retention after 350 cycles (0.5 C) and >80% after 600 cycles (1.0 C).

Conclusions:

• Small biomolecules, exemplified by orotic acid (OA), are effective fillers for enhancing polymer electrolytes.
• OA's dual mechanism of promoting ion dissociation and forming a stable SEI significantly improves battery performance and longevity.
• This strategy offers a promising route towards developing advanced, sustainable polymer electrolytes for high-performance lithium-ion batteries.