The Application of Polyrotaxane Cellulose Composite Materials in Quasi-Solid Electrolytes

Area of Science:

• Materials Science
• Electrochemistry
• Polymer Chemistry

Background:

• Cellulose is a sustainable, biodegradable, and abundant material, making it a promising alternative to petroleum-based resources.
• Developing advanced materials for energy storage is crucial for sustainable energy solutions.
• Thermoplastic polyurethane (TPU) is a versatile polymer with potential for composite applications.

Purpose of the Study:

• To synthesize a novel TPU-cellulose composite (TPU-C) for use as a separator in quasi-solid polymer electrolytes (QPEs).
• To evaluate the electrochemical performance of the TPU-C composite in lithium-ion batteries.
• To investigate the underlying mechanisms of the composite's performance using computational methods.

Main Methods:

• Synthesis of a rotaxane-based supramolecular polymer derived from TPU and its combination with cellulose.
• Fabrication of acrylate-based QPEs utilizing the TPU-C composite as a separator.
• Electrochemical characterization including ionic conductivity, lithium-ion transference number, and electrochemical stability window measurements.
• Battery performance testing with LiFePO4 (LFP) and high-voltage NCM622 cathodes.
• Density functional theory (DFT) calculations to analyze electrochemical behavior.

Main Results:

• The TPU-C composite demonstrated excellent performance as a separator for QPEs.
• The polymer electrolyte exhibited high ionic conductivity (0.16 mS cm⁻¹ at room temperature) and a high lithium-ion transference number (0.63).
• The electrochemical stability window extended up to 4.7 V, and battery cells showed good capacity retention (88.8% after 100 cycles with LFP, 65.8% after 100 cycles with NCM622).

Conclusions:

• The developed TPU-cellulose composite is a highly effective separator for advanced lithium-ion batteries.
• The composite material contributes to enhanced ionic conductivity and electrochemical stability in polymer electrolytes.
• This research highlights the potential of cellulose-based composites for next-generation energy storage devices.