Polyimide nanofiber membrane coated with cerium dioxide nanolayer on surface and preparation method of polyimide nanofiber membrane

Abstract

The invention provides a polyimide nanofiber membrane coated with a cerium dioxide nanolayer on the surface and a preparation method of the polyimide nanofiber membrane. The preparation method comprises the following steps of firstly, preparing a polyimide nanofiber membrane by adopting an electrostatic spinning method, carrying out surface etching treatment by using an alkaline solution, acidifying to prepare a surface carboxylated polyimide nanofiber membrane, and then putting the surface carboxylated polyimide nanofiber membrane into dilute ammonia water for ammoniation; and placing the polyimide fiber membrane in a precursor solution of cerium dioxide for a reaction, then treating the polyimide fiber membrane with hydrogen peroxide, and finally performing high-temperature heat treatment to prepare the polyimide nanofiber membrane coated with the cerium dioxide nanolayer on the surface in one step. The mechanical property, the thermal dimensional stability, the wettability and the high temperature resistance of the polyimide nanofiber membrane are improved through coating of the cerium dioxide nanolayer. The method disclosed by the invention is simple in operation process, easy to processize and high in production efficiency; and prepared composite nanofiber fully combines the advantages of polyimide and an inorganic layer and has a wide application prospect in the fields of lithium battery diaphragms, catalysis, filtration, flame retardance, dust removal and the like.

Description

technical field [0001] The invention belongs to the technical field of polyimide nanofiber membranes, and relates to a preparation method of a polyimide nanofiber membrane with a surface coated with a cerium dioxide nanolayer and the prepared polyimide nanofiber membrane with a surface coated with a cerium dioxide nanolayer. imide nanofiber membrane. Background technique [0002] Lithium-ion batteries have been widely concerned and widely used since their appearance in 1991 because of their high voltage, small size, high energy density, long cycle life, and fast charging and discharging. The 2019 Nobel Prize in Chemistry is awarded to scientists who have made outstanding contributions to the development of lithium-ion batteries. The emergence of lithium-ion batteries has changed people's way of life. The battery separator enjoys the reputation of the "third electrode" of the battery and plays an important role in the production and use of the battery. This is because many ...

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Problems solved by technology

The polyolefin separator has good mechanical properties and moderate porosity, but there are some problems due to its own structural characteristics: (1) The non-polar nature makes the electrolyte wettability poor, and the liquid absorption rate is low, resulting in the ionization of the battery. The conductivity is low, the internal resistance is large, and it takes a long time to wait for the electrolyte to infiltrate the separator after the electrolyte is injected during the battery production process, which affects the production efficiency of the battery to a certain extent

(2) The softening temperature and melting point of the polyolefin separator (PP is 165°C, PE is 135°C) are both low, and the battery can easily generate local high temperature during high-power charging and discharging, causing the separator to melt and rupture, and the positive and negative electrodes are in contact An internal short circuit occurs, which eventually leads to a safety accident of the battery

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