Tetraphenylborate-based anionic metal-organic framework as an efficient single-ion conductor for solid-state sodium...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Rechargeable sodium batteries (RSBs) are crucial for post-lithium energy storage.
• Liquid electrolytes in RSBs cause safety issues like dendrite growth and performance degradation.
• Current dual-ion electrolytes exacerbate sodium metal growth, limiting RSB applications.

Purpose of the Study:

• To develop a safe and high-performance solid-state electrolyte for RSBs.
• To address the limitations of flammable liquid electrolytes and dual-ion systems.
• To create a versatile single-ion conductive electrolyte using anionic metal-organic frameworks (MOFs).

Main Methods:

• Synthesized a tetraphenylborate-supported anionic MOF using a sodium tetraphenylborate building block and a Zr6-oxo cluster.
• Investigated the ionic conductivity, activation energy, and Na+ transference number of the MOF electrolyte.
• Fabricated and tested solid-state RSBs using the developed MOF electrolyte, evaluating their performance and stability.

Main Results:

• The anionic MOF electrolyte demonstrated high ionic conductivity (0.407 mS cm-1), low activation energy (0.19 eV), and a high Na+ transference number (0.90).
• Solid-state RSBs exhibited excellent interfacial compatibility, high capacity (529 mA h g-1 at 0.1 A g-1), and long cycle life (93.8% retention after 2500 cycles).
• The MOF electrolyte enabled stable battery operation across a wide temperature range (-40 to 70 °C) and current densities (0.1 to 10 A g-1).
• The MOF demonstrated versatility as a single-ion electrolyte for solid-state potassium and zinc batteries.

Conclusions:

• Anionic MOFs are promising solid-state electrolytes for advanced rechargeable batteries.
• The developed MOF electrolyte offers a safer and more efficient alternative to liquid electrolytes in RSBs.
• This work provides a design strategy for anionic porous materials in next-generation energy storage devices.