Study on the preparation of three-dimensional flexible self-supporting thick electrodes using phase transformation method and their electrochemical performance

Abstract

With the rapid development of flexible electronic devices, wearable equipment, and implantable medical devices, there is an increasing demand for flexible energy storage devices. Polyacrylonitrile and polyurethane are cross-linked and polymerized using the phase transformation process under the action of a non-solvent phase, resulting in a three-dimensional skeleton for flexible, self-supporting thick electrodes that exhibit a three-dimensional porous structure. In this structure, polyurethane serves as a flexible component, while the chain-like conductive agent KB provides electronic conduction pathways for the active material. Carbon nanofibers function as bridges between active particles, facilitating electronic transfer among them. Additionally, carbon nanotubes in the non-solution phase form an external conductive network within the three-dimensional electrode. The prepared three-dimensional porous flexible thick electrodes can control the electrode thickness to be above 300 μm, with a capacity retention rate of 97.74 % after 200 cycles. They still exhibit a specific capacity of 133.39 mAh g⁻¹ at a current density of 2.0C. This represents a significant improvement compared to traditional self-supporting electrodes.