Preparation method of porous film for battery, porous film, battery diaphragm and battery

Abstract

The invention relates to a preparation method of a porous film for a battery, the porous film, a battery diaphragm and the battery, and the method comprises the following steps: preparing a polymer A with 100% definite elongation strength of 0.5-20 MPa, a polymer B which is a copolymer containing a polyester chain segment and has a tensile elastic modulus of 800 MPa or more, blending the polymer A and the polymer B in a mass ratio of (40-70):(60-30) to prepare a blended film, and soaking the blended film in an aqueous solution of pH smaller than 5, taking out the blended film, and drying the blended film to obtain the porous film. The porous film disclosed by the invention has good flexibility and can resist external forces such as stretching and bending to a certain extent, and when the porous film is subjected to the external forces such as stretching and bending, the pore diameter change of internal pores of the porous film is relatively small, and the properties such as air permeability of the pores and adverse effects caused by the pore diameter change are not influenced; and the preparation method is simple and feasible, and is suitable for automatic control and large-scale production.

Description

technical field [0001] The invention relates to a porous film, in particular to a preparation method for a battery porous film, a porous film, a battery diaphragm and a battery. Background technique [0002] With the development of science and technology, people's demand for energy is increasing. Among them, electric energy is cheap, convenient and environmentally friendly. More and more products use electric energy as the driving force, and electronic products have developed rapidly. Mobile electronic products such as computers, electric vehicles, and robots are also developing rapidly, which makes the field of batteries, especially lithium-ion batteries, develop rapidly. People are committed to improving the energy storage and conversion efficiency of batteries. [0003] At the same time, as electric energy and batteries are used more and more widely, many electronic products and components need to have a certain degree of flexibility and be able to withstand external forc...

AI Technical Summary

Problems solved by technology

However, since the battery separator is a porous film containing micropores, and the pore size is nanoscale, if the battery is deformed by external force during use, the battery separator will also deform. If the flexibility of the separator is not enough, and during the deformation process The pore size of the diaphragm also changes greatly, which will affect the air permeability and use effect of the battery, and affect the safety and service life of the battery

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