Exploring the Capacity Limit: A Layered Hexacarboxylate-Based Metal-Organic Framework for Advanced Lithium Storage

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Previous research indicated a correlation between carboxylate groups and energy density in metal-organic frameworks (MOFs).
• MOFs are porous crystalline materials constructed from metal ions and organic linkers, offering tunable properties.

Purpose of the Study:

• To synthesize and evaluate a novel metal-organic framework (MOF) material for enhanced lithium storage applications.
• To investigate the role of carboxylate-metal units in the electrochemical performance of MOF-based anodes.

Main Methods:

• Synthesis of a layered MOF, Ni-BHC, using 1,2,3,4,5,6-benzenehexacarboxylic acid.
• Thermal evacuation of the synthesized MOF for activation.
• Electrochemical testing of the activated MOF as an anode for lithium storage.
• Density functional theory (DFT) calculations and O soft X-ray absorption spectroscopy (XAS) for mechanistic insights.

Main Results:

• The synthesized Ni-BHC MOF exhibited a high reversible capacity of 1261.3 mA h g^-1 at a current density of 100 mA g^-1.
• The performance significantly surpassed previously reported MOF-based anode materials.
• DFT and O soft XAS indicated the crucial role of abundant carboxylate-metal units in the electrochemical lithium storage process.

Conclusions:

• The Ni-BHC MOF demonstrates superior performance as a lithium-ion battery anode material.
• The layered structure and rich lithiation sites contribute to its high capacity and fast kinetics.
• Abundant carboxylate-metal units are key to the enhanced electrochemical activity in MOF anodes.