An Inorganic Layered Coordination Polymer as High-Performance Solid-State Electrolyte for Stable Lithium Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Solid-state electrolytes (SSEs) face challenges like low ionic conductivity and interfacial instability, limiting solid-state lithium metal battery (SSLMB) development.
• Heterogeneous ion flux and unstable interfaces are key hurdles for high-energy-density SSLMBs.

Purpose of the Study:

• To engineer a novel SSE using a two-dimensional Hofmann-type framework material (HFM) for improved Li+ conductivity and interfacial stability.
• To investigate the effect of guest solvent molecules on HFM structure and Li+ transport properties.

Main Methods:

• Synthesized a 2D HFM and modulated its interlayer spacing using different solvent molecules.
• Characterized the SSE's ionic conductivity and electrochemical performance in Li||Li symmetric and LiFePO4||Li full cells.
• Analyzed the Li-electrolyte interface using techniques to identify the solid electrolyte interphase (SEI) composition.

Main Results:

• Achieved high ionic conductivity (1.51 mS cm-1) using methoxymethane (DME) as the guest molecule, creating selective Li+ pathways.
• Demonstrated stable cycling (>3000 h) in Li||Li symmetric cells and high capacity retention (96.3% after 500 cycles) in LiFePO4||Li full cells.
• Observed the formation of a Li3N-rich SEI layer, enhancing lithium anode stability.

Conclusions:

• The nanoconfined electrolyte system effectively bridges ion-selective nanochannels with a stabilized interphase.
• This HFM-derived SSE offers a promising platform for next-generation high-energy-density solid-state batteries.
• Modulating interlayer spacing with guest molecules is a viable strategy for designing advanced SSEs.