A Fiber-Based 3D Lithium Host for Lean Electrolyte Lithium Metal Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium metal anodes are crucial for high-energy batteries but suffer from short cycle life.
• Implementing 3D hosts with lean electrolytes is challenging for practical energy density.
• Existing 3D hosts often fail to fully utilize pore volume under lean electrolyte conditions.

Purpose of the Study:

• To develop a lightweight, easily fabricated 3D host for lithium metal anodes.
• To enable efficient operation with lean electrolytes for high-energy density lithium-metal batteries.
• To enhance the lithiophilicity and pore utilization of the 3D host.

Main Methods:

• Fabrication of a 3D host using vapor-grown carbon fibers (VGCF) and a rubidium nitrate additive.
• Characterization of pore structure (≈3 µm pores, 80% porosity) and lithiophilicity enhancement.
• Electrochemical testing in half-cells and full cells with LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes under lean electrolyte conditions.

Main Results:

• The 3D host achieved an average coulombic efficiency of 99.36% over 860 cycles in half-cells.
• Full cells demonstrated 80% capacity retention over 176 cycles at C/2 with a lean electrolyte (3 g Ah⁻¹).
• The VGCF host effectively utilized its pore volume, crucial for lean electrolyte performance.

Conclusions:

• A facile and scalable method for fabricating advanced 3D lithium hosts was developed.
• The VGCF-based 3D host significantly improves the cycle life and stability of lithium metal anodes.
• This work paves the way for practical, high-energy lithium-metal batteries utilizing lean electrolytes.