High Performance Polyimide Nanofiber Membrane Made By ABC-spinning Technology

This paper gave a concise review on the history of eletrospinning technology, which becomes one of the effective methods to produce polymer nanofibers, on the development and market of lithium-ion battery and on the characteristics of polyimides. However, the low producing speed is the fatal problem of electrospinning; the low heat-resistance of separator is probably the hidden trouble of Li ionic battery. A topic was presented here for speeding up the preparation polymer nanofibers. The technology of high-speed preparing polymer nanofibers was achieved by combining the technologies of high-speed air blowing and electrospinning. The as-prepared polyimide nanofibers using the modified technology were examined to have high performance characters. The high performance polyimide nanofiber membrane was successfully used as the lithium-ion battery separators.The work of this paper focused on the following two parts:1. The first is to design a new device for high-speed preparation of polymer nanofibers by combining two technologies of high-speed air blowing and electrospinning. The novel technology was called "spinning by air-blowing charged polymer solution", shortened as ABC-spinning. The ABC-spinning technology was tested to produce polymer nanofibers at a speed of 10 times higher than that by using normal electrospinning technology. The diameters of polymer nanofibers made by ABC-spinning ranged from 1 nm to several microns. The performances of the ABC-spun polymer nanofibers were the same as that of the normal electrospun nanofibers.2. PMDA/ODA polyimide nanofiber membranes were prepared in a large-scale by using ABC-spinning technology. The structure and properties of the ABC-spun PMDA/ODA polyimide nanofiber membrane were characterized by using scanning electron microscope, tensile tester, dynamic mechanical analyzer and TGA. The gas permeability of the membrane was examined by using a homemade gas permeation-meter. The experimental results showed that the tensile strength of the tested membrane is almost the same in two directions of Machine Direction (MD) and Transverse Direction (TD); the ABC-spun PMDA/ODA polyimide nanofibers have a high thermal stability with a glass transition at 375℃and a thermal degration temperature of 5% weight loss at 554℃; the porosity of the ABC-spun nanofiber membrane (thichness of 40μm) is as high as 87% with a gas permeability of 1040 mL/min·cm~2 at a pressure difference of 0.03 atmosphere. The high thermal stability and high porosity and proper mechanical properties of the ABC-spun nanofiber membrane will find a great market as the lithium-ion battery separators.