Anode-Protective Covalent Organic Framework Layer with Synergistic Cation-Anion Regulation for Dendrite-Free Lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium metal batteries are crucial for next-generation energy storage.
• Lithium dendrite formation hinders Coulombic efficiency and safety.
• Existing anode protective layers lack simultaneous control over cation and anion dynamics.

Purpose of the Study:

• To develop a protective layer for lithium metal anodes with molecular-level control over ion transport.
• To investigate the synergistic effects of cation and anion regulation for stable lithium deposition.
• To enhance the Coulombic efficiency and cycling stability of lithium metal batteries.

Main Methods:

• Construction of a binary cooperative magnesium porphyrin-based covalent organic framework (Mg-Por-COF).
• Characterization of Mg-Por-COF for its ability to regulate Li+ and TFSI- anion dynamics.
• Electrochemical testing of Li/Mg-Por-COF-Cu cells and LiFePO4/Mg-Por-COF-Li full cells.
• Computational simulations to understand ion transport mechanisms.

Main Results:

• Mg-Por-COF promotes Li+ desolvation and immobilizes TFSI- anions, preventing space charge accumulation.
• Achieved smooth and compact Li deposition even at high areal current densities (10 mA cm-2).
• Li/Mg-Por-COF-Cu cells demonstrated 400 cycles with 98.3% average Coulombic efficiency.
• LiFePO4/Mg-Por-COF-Li full cells showed 324 cycles with 99.1% average Coulombic efficiency.

Conclusions:

• Structurally designed covalent organic frameworks offer superior protective layers for high-performance energy storage.
• Synergistic cation-anion regulation is key to achieving uniform lithium deposition and battery stability.
• Mg-Por-COF presents a promising, sustainable approach for advanced lithium metal batteries.