Hydroxyethyl Cellulose as Water-Soluble Co-Binder for High Mass Loading LiNi_0.5Mn_1.5O₄ Lithium-Ion Battery Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• High-voltage cobalt-free LiNi0.5Mn1.5O4 (LNMO) cathodes offer potential for sustainable lithium-ion batteries (LIBs).
• Achieving high mass loading electrodes with traditional binders like polyvinylidene difluoride (PVDF) is challenging, especially in water-based processing.
• Fluorine-free and water-soluble binders are crucial for environmentally friendly battery manufacturing.

Purpose of the Study:

• To develop a sustainable, fluorine-free, water-soluble binder system for high-voltage LNMO cathodes.
• To enable high mass loading electrodes with optimized electrochemical and mechanical properties.
• To demonstrate the performance of LIBs utilizing these advanced cathode materials.

Main Methods:

• Utilizing 2-hydroxyethyl cellulose (HEC) as a primary binder, crosslinked with citric acid and guar gum (GG).
• Fabricating high mass loading LNMO electrodes (approx. 15 mg cm⁻²).
• Assembling full lithium-ion cells with graphite anodes and evaluating their electrochemical performance over 200 cycles.

Main Results:

• The co-crosslinked HEC-GG binder system facilitated homogeneous dispersion and improved electrode mechanical properties.
• High mass loading LNMO electrodes (15 mg cm⁻²) exhibited comparable capacity retention to PVDF-based reference electrodes.
• Lithium-ion cells achieved an areal capacity of ~2.2 mAh cm⁻² with 82% capacity retention after 200 cycles.

Conclusions:

• A novel, sustainable binder system based on co-crosslinked HEC and GG enables high-performance, high mass loading LNMO cathodes.
• This water-processed, fluorine-free approach is promising for environmentally friendly and efficient lithium-ion battery manufacturing.
• The developed system offers a viable alternative to conventional binders for advanced energy storage applications.