Method for preparing polyimide porous nanofiber electrode diaphragm

Abstract

The invention discloses a method for preparing a polyimide porous nanofiber electrode diaphragm. The method comprises the following steps: carrying out condensation reaction by adopting binary organic amine and binary organic acid anhydride in an organic solvent, thereby obtaining a polyamide acid solution; adding a soluble metal salt to prepare a spinning precursor, preparing a polyamide acid-metal salt electrostatic spinning fiber diaphragm by virtue of high-voltage electrostatic spinning, and performing thermal imidization treatment, thereby obtaining a polyimide-metallic oxide fiber composite diaphragm; and dissolving the composite diaphragm in an inorganic acid aqueous solution for performing acid treatment, so that metallic oxide nanoparticles are converted into soluble metal salts so as to be dissolved in the inorganic acid aqueous solution so as to obtain the polyimide nano/micron porous fiber diaphragm. The method has the advantages that according to the polyimide nano/micron porous fiber diaphragm, the mechanical strength, thermal stability, liquid holdup, permeability, wettability and migration rate of conductive ions of the diaphragm can be effectively improved, and the liquid junction resistance of the diaphragm and electrolyte and the contact resistance of the diaphragm and the electrode can be reduced, so that the electrochemical performance of a supercapacitor is improved.

Description

technical field [0001] The invention belongs to the field of nanomaterial preparation, in particular to a method for preparing a polyimide porous nano-micron fiber electrode diaphragm for a supercapacitor. Background technique [0002] The electrode separator is one of the important components of the supercapacitor. It is placed between the two poles of the capacitor to separate the positive and negative electrodes, preventing the direct contact between the active materials of the two poles and causing a short circuit. At the same time, it does not prevent the migration of ions in the capacitor and allows the ions to pass through freely. , which requires the separator to have a certain fiber diameter, pore size and pore size distribution, and to have stable physical and electrochemical properties, and small internal resistance, good electric starting performance, etc., the excellent performance of the separator is very important for improving the high power of the supercapaci...

AI Technical Summary

Problems solved by technology

[0003] At present, due to the low melting temperature, high heat shrinkage ratio and low porosity of the porous films such as polyethylene and polypropylene used as electrode separator materials, supercapacitors will be overheated and overcharged during high-power charging and discharging, which will lead to The diaphragm heat shrinks or even melts, causing the electrode diaphragm to rupture, which is prone to accidents such as thermal runaway and explosion

[0004] CN 101974828A and CN 102251307A adopt the electrospinning method to prepare polyamide fiber membrane, which has the characteristics of strong tear resistance, high porosity, high and low temperature resistance and excellent mechanical properties, but the fiber itself is smooth and non-porous, so that the membrane can last Low fluid volume, insufficient ion permeability

[0005] CN 102277648A uses a mixed solution of inorganic nanoparticles and polyamic acid to undergo electrospinning, mechanical rolling and high-temperature thermal imidization to prepare an inorganic / organic composite polyimide-based nanofiber membrane, which has high porosity and mechanical strength However, the addition of inorganic nanoparticles reduces the spinnability and separator insulation of the polymer, resulting in uneven pore size distribution of electrospun fibers, increased leakage current, and poor wettability of organic electrolytes.

[0006] CN 104213333A adopts electrospinning method to prepare polyimide / polyolefin composite fiber film, and then conducts controlled heat treatment to make polyolefin fiber heat and micro-melt, form fusion points between polyimide ultrafine fibers, and obtain cross-linked Structured polyimide / polyolefin composite fiber membrane to improve the mechanical properties and dimensional stability of the fiber membrane, but this method uses the second electrospinning membrane, the process controllability is poor, and the polyimide diaphragm Mechanical and electrochemical properties deteriorate with the addition of the second component

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