Cobalt-Phthalocyanine-Derived Molecular Isolation Layer for Highly Stable Lithium Anode

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Lithium dendrite formation due to uneven anion consumption and space charge effects hinders lithium-metal battery safety and performance.
• Developing stable solid electrolyte interphases (SEI) is crucial for practical lithium-metal battery applications.

Purpose of the Study:

• To investigate the use of cobalt phthalocyanine as an electrolyte additive to mitigate lithium dendrite growth.
• To enhance the cycling stability and performance of lithium-metal batteries.

Main Methods:

• Utilized cobalt phthalocyanine as a planar molecular additive in the electrolyte.
• Formed a dense molecular layer on the lithium anode surface.
• Analyzed the SEI composition using X-ray absorption near-edge spectroscopy (XANES).
• Tested Li|Li symmetric cells and Li|lithium iron phosphate (LFP) full cells under various conditions.

Main Results:

• The cobalt phthalocyanine additive effectively complexes with Li ions, reducing the space charge effect and suppressing side reactions.
• A stable SEI layer composed of amorphous lithium fluoride (LiF) and lithium carbonate (LiCO3) was formed.
• Li|Li symmetric cells demonstrated over 700 hours of stable cycling at 3 mAh cm⁻².
• Li|LFP full cells achieved over 200 cycles with lean electrolyte conditions (3 μL mg⁻¹).

Conclusions:

• Cobalt phthalocyanine is a promising electrolyte additive for stabilizing lithium anodes in lithium-metal batteries.
• The developed strategy significantly improves battery cycling stability and performance, particularly under demanding conditions.