Nanoparticle coated lithium ion battery diaphragm and preparation method thereof

Abstract

The application discloses a nanoparticle coated lithium ion battery diaphragm and a preparation method thereof. The nanoparticle coated lithium ion battery diaphragm comprises a basal membrane and nanoparticles coated on at least one surface of the basal membrane, wherein the nanoparticles have porous structures, and at least a part of channels penetrate the surface of the nanoparticles. The nanoparticle coated lithium ion battery diaphragm employs the nanoparticles with the porous structures to prepare a coating, the nanoparticles with the porous structures have developed channel structures,lithium ions can diffuse in gaps between nanoparticles, and lithium ions can freely diffuse in the internal channels in the porous structures of the nanoparticles, in order to improve porosity of thediaphragm with the nanoparticle coating, and improve wettability of diaphragm electrolyte. The nanoparticle coated lithium ion battery diaphragm keeps heat resistance of the traditional diaphragms with nanoparticle coatings, and at the same time improves conductivity of lithium ions, so that batteries have high rate performance and long circulation performance.

Description

technical field [0001] The present application relates to the field of lithium-ion battery separators, in particular to a lithium-ion battery separator coated with nanoparticles and a preparation method thereof. Background technique [0002] Lithium-ion batteries have been widely used in various daily fields because of their advantages such as high energy density, environmental protection, light weight, good charge and discharge performance, and good safety performance. With the increase of people's demand for clean energy, their usage is also growing. Lithium-ion battery separator is one of the four main materials of lithium-ion batteries. At present, the commonly used commercial lithium-ion battery separators are single-layer or multi-layer porous films of polyolefins such as polyethylene (PE) and polypropylene (PP). [0003] Due to the low melting point of the traditional polyolefin separator, it will shrink after being heated, which will cause a short circuit between t...

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Problems solved by technology

[0003] Due to the low melting point of the traditional polyolefin separator, it will shrink after being heated, which will cause a short circuit between the positive and negative electrodes of the battery and there is a serious safety hazard, and the polyolefin separator has poor wettability to the electrolyte, so people Modified research and development of new diaphragm materials

At present, ceramic diaphragms for lithium-ion batteries have appeared. The ceramics used in commercialized mainstream ceramic coating films are inorganic nano-alumina, boehmite, etc., but these inorganic nano-powders will be densely packed in the pore structure of the base film. Blocking the pores of the diaphragm causes changes in the microstructure of the diaphragm, such as affecting the pore size and pore size distribution of the diaphragm, affecting the porosity and air permeability of the diaphragm, and even affecting the dimensional stability of the diaphragm, which in turn affects ion migration, significantly affecting the ion density of lithium-ion batteries. Migration number and ionic conductivity hinder the transport of lithium ions, thereby affecting battery performance

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