Mechanically Robust Current Collector with Gradient Lithiophilicity Induced by Spontaneous Lithium Ion Diffusion for...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lean-lithium metal batteries offer high energy density but face challenges with cycling stability and safety due to lithium metal management.
• Anode-free lithium metal batteries require precise control over lithium deposition to prevent dendrite formation and capacity loss.

Purpose of the Study:

• To develop a mechanically robust current collector with gradient lithiophilicity for lean-lithium metal batteries.
• To improve the initial Coulombic efficiency and cycling performance of lithium metal batteries.

Main Methods:

• Fabrication of a carbon nanotube framework current collector using physical vapor deposition for precise prelithiation.
• Characterization of the lithiophilic gradient and porous structure using TOF-SIMS, STEM, and EELS.
• Electrochemical testing of LiFePO4 full cells with varying N/P ratios.

Main Results:

• Achieved gradient lithiophilicity in the carbon nanotube framework, promoting preferential lithium deposition at the bottom.
• Significantly increased initial Coulombic efficiency from 77.75% to 95.07% in a LiFePO4 full cell with an ultralow N/P ratio of 0.15.
• Demonstrated 86% capacity retention after 500 cycles at 1C for a full cell with an N/P ratio of 1.43, outperforming copper counterparts.

Conclusions:

• The mechanically robust, lithiophilic gradient carbon nanotube framework effectively suppresses lithium loss and enhances battery performance.
• This approach offers a promising strategy for developing stable and high-energy lean-lithium metal batteries.