Tailoring Interphasial Na⁺ Flux by Fluorinated Covalent Organic Frameworks Toward Robust Anode-Less Na Metal...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium metal batteries offer high energy density but face challenges with interphase instability and sodium dendrite growth.
• These issues limit the practical application and lifespan of sodium metal batteries.

Purpose of the Study:

• To develop a strategy for stabilizing the interphase in sodium metal batteries.
• To enable homogeneous sodium deposition and inhibit dendrite formation using a novel material.

Main Methods:

• Rational design and employment of a fluorinated covalent organic framework (F-COF).
• Utilizing F-COF to homogenize and accelerate Na+ flux for controlled sodium deposition.
• In situ generation of a NaF-rich interphase to suppress dendrite growth.

Main Results:

• Sodium symmetric cells demonstrated high rate capability (10 mA cm-2) and long-term stability (2600 h).
• Na||Na3V2(PO4)3 (NVP) cells achieved over 5000 cycles with minimal capacity decay (≈0.0018% per cycle) at 20 C.
• Anode-less Na||NVP pouch cells showed stable cycling over 150 cycles under demanding conditions (low capacity ratio, lean electrolyte).

Conclusions:

• Fluorinated covalent organic frameworks effectively regulate interphasial Na+ flux and suppress dendrite growth.
• This approach enables high-performance, long-lifespan anode-less sodium metal batteries.
• Presents a new strategy for manipulating interphases in advanced sodium metal batteries.