Lithium battery separator with thermal switch function and preparation method of lithium battery separator

Abstract

The invention discloses a lithium battery separator with a thermal switch function and a preparation method of the lithium battery separator. The lithium battery separator is prepared from the following raw materials in percentage by mass: 60%-90% of homopolypropylene and 10%-40% of a thermosensitive polymer additive, wherein the melting point of the homopolypropylene is 160-170 DEG C; and the thermosensitive polymer additive has a significant thermal expansion effect within a temperature range of 100-140 DEG C. The preparation method comprises the following steps: preparing a polypropylene base membrane through a flow-casting strip and preparing a microporous membrane through step-by-step two-way stretching to prepare the lithium battery separator with the thermal switch function. The prepared lithium battery separator is high in porosity and excellent in pore size distribution uniformity, and has excellent safety performance; the pore closing temperature is about 100-140 DEG C; the film breaking temperature is about 165 DEG C; meanwhile, when the separator is cooled to a room temperature, the closed micropores are opened again; the capacity and the service lifetime of the lithium battery are not affected; and the lithium battery separator can be applied to the field of mobile phone batteries, electric vehicle batteries and the like.

Description

technical field

[0001] The invention relates to the technical field of battery diaphragm preparation, and more specifically relates to a lithium battery diaphragm with a thermal switch function and a preparation method thereof. Background technique

[0002] Rechargeable lithium-ion secondary batteries have the characteristics of long cycle life, high specific energy, no memory effect, fast charging and discharging, and safety and reliability. They have become a research hotspot of new power supply technology in recent years and have been widely used Used in mobile phone batteries, laptop batteries, and electric vehicle batteries. Lithium battery cells are mainly composed of negative electrode materials, positive electrode materials, diaphragms and electrolytes. The porous diaphragm is an important part of the cell. The main function of the diaphragm is to separate the positive and negative electrodes of the battery to prevent short-circuiting between the two electrodes. In ...

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