Multilayer porous battery separator with gradient and continuous change in component ratio and preparation method thereof

Abstract

The invention discloses a multi-layer porous battery separator whose component ratio changes continuously in a gradient and a preparation method thereof, comprising the following steps: ball milling an inorganic powder, drying, and passing through a 200-mesh sieve to obtain a powder of 0.01-50 μm; The sieved powder and polyvinylidene fluoride are added to the organic solvent, stirred vigorously to dissolve and disperse to obtain the casting solution, and the casting solution is cast into a membrane in a casting machine, and then the membrane is solidified and formed in a coagulation bath , and then the membrane is taken out and dried to obtain a porous membrane; the mass ratio of powder and polyvinylidene fluoride is changed, and the process of preparing casting solution, casting, and drying is repeated to prepare powder and polyvinylidene fluoride with different mass ratios. Diaphragm, the above-mentioned diaphragm is cut, and then stacked into a multi-layer porous diaphragm according to the mass ratio of powder and polyvinylidene fluoride from high to low or from low to high; put the multi-layer porous diaphragm into the In the same mold, the multi-layer porous battery separator with gradient and continuous change of component ratio is obtained by pressing.

Description

technical field [0001] The invention relates to a method in the field of lithium-ion batteries, in particular to a multilayer porous battery separator whose component ratio continuously changes in gradients and a preparation method thereof. Background technique [0002] With the development of the economy, people's demand for energy is gradually increasing. In terms of energy structure, nearly 80% of energy comes from non-renewable resources such as petroleum, coal, and natural gas, and the use of these resources has also brought serious environmental pollution problems to people. In recent years, people have gradually focused on renewable energy such as solar energy, wind energy, and geothermal energy. However, these energy sources are generally scattered, random, and intermittent. The key to exploit. Batteries, as a kind of power storage device, ensure the continuity of energy supply. Compared with secondary batteries such as traditional lead-acid batteries, nickel-cadm...

AI Technical Summary

Problems solved by technology

The above-mentioned organic-inorganic composite diaphragm is either coated with inorganic particles on the organic polymer, or blended with the inorganic particles and the organic polymer. Due to the different structures of the organic matter and the inorganic particles, the heat resistance temperature and thermal expansion coefficient of the two are different. There are obvious differences in the wettability of each other, so in the actual use process, it will inevitably cause delamination, peeling, cracking, etc.