Abstract:

Polytetrafluoroethylene fibrosability was utilized to create a dry, self-supporting film by prefibrosing the raw material into a uniform mixture, followed by hot roller pressing. The resulting dry diaphragm achieved a thickness of 120—200 μm and a surface weight capacity of 36—60 mg/cm², 2—4 times higher than current commercial wet electrode surface loads. Scanning electron microscopy (SEM) analysis of the membrane's surface and cross-section showed that the original granular polytetrafluoroethylene binder was fully fibrosed during mixing and hot pressing. The nanofibrous binder, formed during the preparation process, was evenly distributed across the electrode film, with polytetrafluoroethylene fibers and the conductive agent surrounding active particles, creating an abundant "3D" network structure. The diaphragm displayed excellent lyophilic properties, with measured optical contact angles ranging from 97° and 112°. The membrane electrode exhibited strong mechanical properties, with a maximum tensile force of 2.64 MPa, and an elongation is of 34.64%, ensuring the film's integrity during the winding process. The electronic resistivity of the diaphragm is as low as 13.58 mΩ·cm. For the 200 μm super-thick electrode, the first charge-discharge efficiency reached 87.51%, with a specific discharge capacity of 209.60 mAh/g, and a maximum discharge gram capacity of 160mAh/g at 1C ratio. This study demonstrates the feasibility of polytetrafluoroethylene fibrosis for advancing low-cost, large-scale electrode preparation technology, and provides a reliable solution for the efficient use of energy.

Key words: dry technique, self-supporting film, polytetrafluoroethylene, high toughness, high conductivity