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

## TL;DR

This paper explores using cellulose composites in battery electrolytes, showing good performance and stability.

## Contribution

A TPU-cellulose composite is developed for quasi-solid electrolytes with high conductivity and stability.

## Key findings

- The composite electrolyte achieved 0.16 mS cm−1 ionic conductivity at room temperature.
- The electrolyte showed a lithium-ion transference number of 0.63 and 4.7 V stability.
- Cells with LFP and NCM622 cathodes retained significant capacity after 100 cycles.

## Abstract

Due to its affordability, widespread availability, non-toxicity, biodegradability, and renewability, cellulose is considered a crucial material for addressing the depletion of petroleum resources. In this study, a rotaxane-based supramolecular polymer derived from thermoplastic polyurethane (TPU) was synthesized and combined with cellulose to create a TPU–cellulose composite (TPU-C). This composite was employed as a separator for acrylate-based quasi-solid polymer electrolytes (QPEs). The polymer electrolyte demonstrated a high ionic conductivity of 0.16 mS cm−1 at room temperature, a lithium-ion transference number of 0.63, and an electrochemical stability window extending up to 4.7 V. When paired with a LiFePO4 (LFP) cathode, the coin cell retained 88.8% of its capacity after 100 cycles at 1 C. A cell assembled with Li and a high-voltage NCM622 cathode maintained a capacity of 65.8% after 100 cycles at 0.3 C. Additionally, the excellent electrochemical performance was analyzed through density functional theory (DFT) calculations to identify the underlying reasons for its outstanding behavior. This study offers new insights into expanding the application potential of cellulose-based composite materials.