Compatible bridged interphase with enhanced Li ion migration for durable quasi-solid-state lithium metal batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Solid-state lithium metal batteries (SSLMBs) face challenges with interfacial electrochemistry due to mismatched lithium ion diffusion rates.
• This mismatch leads to interface degradation and lithium dendrite formation, hindering battery performance and safety.

Purpose of the Study:

• To develop an interfacial ion migration modulator to improve lithium ion transport between ceramic-polymer composite electrolytes and lithium metal.
• To investigate the role of lithiophilic nanoscale metals in stabilizing the solid-electrolyte interphase (SEI) layer.

Main Methods:

• Theoretical simulations and spectroscopic measurements were used to screen various lithiophilic metals.
• Electrochemical tests, including symmetric cell and full cell battery tests, were conducted.
• In situ formation and characterization of the solid-electrolyte interphase (SEI) layer were performed.

Main Results:

• Platinum (Pt) was identified as the optimal metal, forming a Li-Pt alloy SEI layer with a coherent crystal structure.
• The Li-Pt alloy modulator reduced the internal lithium diffusion energy barrier and balanced interfacial ion transport and nucleation rates.
• Symmetric cells with the Pt modulator achieved 1900 hours of cycling with a low overpotential of 10.7 mV.
• A quasi-solid-state lithium metal battery with a LiFePO4 cathode demonstrated improved cycling stability.

Conclusions:

• The interfacial ion migration modulator, particularly the Li-Pt alloy, effectively regulates interfacial ion transport and inhibits defect formation in SSLMBs.
• This approach significantly enhances the cycling stability and lifespan of solid-state lithium metal batteries.
• The findings provide crucial insights into designing stable interfaces for next-generation energy storage devices.