Constructing dendrite-suppressing separators based on cellulose acetate and polyoxometalates toward uniform lithium...

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Lithium metal batteries (LMBs) face challenges from lithium dendrite penetration, hindering their safety and cycle life.
• Functionalized separators are crucial for suppressing dendrite growth and enabling stable LMB operation.

Purpose of the Study:

• To develop a novel self-supporting separator material for lithium metal batteries.
• To investigate the efficacy of cellulose acetate and Keggin-type polyoxometalate (CA/PMo12) in inhibiting lithium dendrites and enhancing battery performance.

Main Methods:

• Synthesis of a novel CA/PMo12 composite separator.
• Characterization of the separator's structure, mechanical strength, and electrolyte uptake.
• Electrochemical testing of Li//Li symmetric cells and LiFePO4//Li cells.
• Density functional theory (DFT) calculations to understand ion adsorption and migration mechanisms.

Main Results:

• The CA/PMo12 separator exhibits a uniform 3D porous grid architecture, effectively inhibiting lithium dendrites.
• Improved mechanical strength, electrolyte uptake, and Li+ anchoring ability were observed.
• DFT calculations confirmed enhanced Li+ adsorption and migration due to the PMo12-CA coordination.
• Li//Li symmetric cells demonstrated excellent plating/stripping efficiency over 1075 cycles.
• LiFePO4//Li cells achieved a superior reversible capacity of 90 mA h g-1 after 100 cycles.

Conclusions:

• The CA/PMo12 composite separator is a promising material for dendrite-free lithium metal batteries.
• The unique structure and chemical properties of CA/PMo12 significantly enhance battery safety and cycle life.
• This work provides a new strategy for designing advanced separators for high-performance energy storage devices.