| Polyimide (PI) is a kind of polymer containing imide ring on its main chain. Due to the stability of the existence of the aromatic ring and imide ring, most of the aromatic polyimide have very good heat resistance. But due to its unique structure, polyimide needs high temperature processing imide into a ring in the synthesis and does not dissolve in any solvent after the ring formation. It directly limited his application in real life. This paper introduces a simple polyimide synthesis method. Then uses polyimide high temperature resistance, solvent resistance to modify the lithium ion battery cathode material and polyurethane. The main content is divided into three parts:(1) Preparation and characterization of polyimide In this chapter, TDI and PMDA are used as principal raw material, using one-pot method under a certain temperature to prepare imines directly into ring with outstanding performance. The influence on the structure and performance of the ratio between TDI and PMDA is discussed. FT-IR,SEM,TGA and chemical endurance is used to characterize the structure and performance.It shows that the polyimide was synthesized, and the polyimide has very good heat resistance and solvent resistance. With the increase of TDI and PMDA proportion, the molecular weight of polyimide is increased and rigid structure ratio as well as heat resistance, solvent resistance performance enhances.(2)Preparation and characterization of Polyimide coating lithium ion battery cathode material In this chapter, TDI and PMDA are used as the main raw material to prepare polyimide precursor. Then the polyimide gel polymer electrolyte method is used to the directional nano coating on lithium ion battery cathode material LiNi0.8 Co0.15 A10.05 O2.Aiming to use the excellent solvent resistance, high temperature resistance, resistance to electrolyte of polyimide to reduce electrolytic corrosion on battery cathode material its high temperature performance loss as well as exothermic reaction between positive electrode materials and electrolyte interface and increase the circulation of the battery performance. By changing the coating ratio, the electrochemical performance of lithium ion battery anode materials under different coating proportion is investigated. FT-IR,XRD,TGA and electrochemical workstation is used to characterize the structure and performance. The result shows that LiNi0.8 Co0.15 A10.05 O2 is coated by Polyimide, and it has no effect on the lithium ion battery cathode material. Imide coating of the cathode material will reduce the first charge and discharge capacity of the battery, but can slow down the battery the rate of discharge specific capacity loss.And when the addition amount of polyimide is 0.1%,the reduction of specific storage battery is the mostly slow. The coating of polyimide reduces the specific discharge capacity. The specific discharge capacity reduces with the increasing of the amount of polyimide.(3)Preparation and characterization of polyurethane/polyimide composite materials With the changing amount of polyimide, polyurethane/polyimide composite materials is synthesized. FT-IR,DSC,TG, tensile properties and chemical endurance is used to characterize the structure and performance of the composite membrane. The result shows that with the increasing of the amount of polyimide, the polyurethane/polyimide composite tensile properties showed a trend of decreasing after increasing. Breaking elongation rate decreased.When polyimide content is 20%, the tensile strength reached maximum. Polyimide modified polyurethane, can improve the heat resistance properties of polyurethane, the glass transition temperature of polyurethane moves to high temperature range. And with the increasing amount of polyimide, the effect is significant. The as synthesized polyurethane/polyimide composite membrane has good water resistance, acid and alkali resistant ability. With the increase of the content of polyimide,the water resistance, acid and alkali resistant ability of the membrane are increased. |
PDF Full Text Request