Understanding Binding of Chitosan to Graphene in Li-Ion Battery Anodes from First-Principles

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Chitosan is a water-soluble, biodegradable biopolymer with potential as a binder in lithium-ion battery graphite anodes.
• Polyvinylidene fluoride (PVDF) is the common binder, but chitosan offers advantages due to its properties.

Purpose of the Study:

• To investigate the binding properties of chitosan on graphene/graphite surfaces using density functional theory.
• To explore how graphene functionalization affects chitosan binding for potential use in energy devices.

Main Methods:

• Density functional theory (DFT) with van der Waals interactions was employed.
• Analysis of electronic charge redistribution, Bader charges, and electronic structure changes were performed.

Main Results:

• Chitosan physisorbs horizontally on graphene/graphite with binding energy less than half that of PVDF.
• Graphene functionalization with defects, OH, and LiF, and exposure to charged ions significantly increases chitosan binding.
• Room temperature enhances binding on oxygen- or OH-functionalized graphene.

Conclusions:

• Chitosan's binding can be tuned through graphene functionalization and environmental conditions (pH, temperature).
• This study provides a baseline for understanding chitosan interactions with electrode materials for eco-friendly energy devices.