Constructing Non-Confined Fast Lithium-Ion Transport Highway in Metal-Phosphonate-Organic Framework Through...

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Batteries

Background:

• Solvent-free all-solid-state electrolytes face challenges in achieving both efficient salt dissociation and rapid ion conduction.
• Existing solid electrolytes often struggle with performance limitations, particularly at low temperatures.

Purpose of the Study:

• To develop a novel metal-phosphonate organic framework (MPOF)-based electrolyte for fast, non-confined lithium-ion conduction.
• To overcome the limitations of traditional solid-state electrolytes by enhancing salt dissociation and ion transport.

Main Methods:

• Utilized a eutectic dissociation strategy within dry-processed MPOFs to unlock ion dissociation via dynamic ion-ligand interactions.
• Engineered MPOFs with abundant phosphonate groups and oxygen vacancies to facilitate lithium salt dissociation and ion transport.
• Investigated the structural features, including nano-channels and alternating charged sites, that promote rapid Li+ transport.

Main Results:

• Achieved an ionic conductivity of 1.1 × 10⁻⁴ S cm⁻¹ at 30 °C and a high lithium-ion transference number of 0.75.
• Demonstrated long cycle life (>7500 h) in symmetric cells and excellent capacity retention (95% after 1000 cycles) in full cells with a LiFePO₄ cathode.
• Showcased stable operation at low temperatures (-10 °C), maintaining ≈70% of room-temperature capacity in full cells.

Conclusions:

• The MPOF@Li electrolyte, leveraging a eutectic dissociation strategy, successfully enables fast, non-confined lithium-ion conduction in solvent-free solid-state systems.
• The unique ligand channel within the MPOF structure facilitates efficient Li+ transport, leading to superior electrochemical performance and low-temperature operability.
• This MPOF-based electrolyte represents a promising advancement for high-performance and reliable solid-state batteries.