Fiber cloth-based lithium ion battery diaphragm as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a fiber cloth-based lithium ion battery diaphragm as well as a preparation method and application thereof. The preparation method comprises the following steps of: preparing composite fine denier fiber yarns taking polyolefin as a core and a blended polymer as a sheath through adopting a composite fiber spinning method technology; and warping and weaving the composite fine denier fiber yarns into warp and weft fiber cloth or arranging fibers in the same direction in a biorthogonal composite laminating manner to obtain weftless cloth, and performing hot pressing by means of a smooth roll to obtain the fiber cloth-based lithium ion battery diaphragm. The preparation method is simple in step, and the batterydiaphragm with high liquid absorption rate, high ionic conductivity and high mechanical property can be prepared without coating slurry on one side or two sides of the diaphragm and stretching, orienting and pore-forming; and a gel layer is attached to polypropylene framework fibers in situ in the production process, that is to say, gel polymers attached to the framework fibers are equivalent, sothat the fiber cloth diaphragm is uniform in thickness, and the porosity and pore size distribution are kept constant.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and in particular relates to a fiber cloth-based lithium-ion battery separator and a preparation method and application thereof. Background technique [0002] Lithium-ion batteries have the advantages of high energy density, high working voltage, no memory effect, excellent cycle rate performance, and environmental friendliness. They are widely used in mobile electronic digital products, electric vehicles and other fields. The separator is an important part of the battery. The performance of the separator determines the internal resistance of the battery, the adhesion to the pole piece and the stability of use, and ultimately affects the capacity, cycle rate performance and safety of the battery. [0003] At present, commercial separators widely used in the market mainly include polyethylene porous membranes, polypropylene porous membranes, and polypropylene / polyethylene / polypropyle...

AI Technical Summary

Problems solved by technology

However, the melting point of the above-mentioned polyolefin material separator is relatively low. When the battery works at a temperature near the melting point of the separator material for a long time, about 145°C, the separator will curl and shrink, resulting in holes, which will cause the battery to short-circuit due to the contact between the positive and negative electrodes; the same lithium branch The growth of dendrites will also have an impact on the separator. When the separator is pierced by dendrites, it will also cause a short circuit in the battery.

[0004] In this regard, heat-resistant polymers have gradually attracted attention in battery separators. For example, the patent CN 102969470 uses polyester materials as raw materials to prepare separators, but polyester cannot be swelled in the electrolyte and cannot be well bonded to the positive and negative electrodes of the battery. , and the large pore size is difficult to control, which also affects the safety of the battery during charging and discharging

Patent CN 108448035 discloses a PP / PET / PE fiber cloth composite battery separator, which dissolves the polyester with lye and then heat-presses to form a film. This method adjusts the aperture of the separator by controlling the distance between fibers and melting polyethylene , instead reduces the controllability of the pore size of the separator, resulting in uneven distribution of the pore size of the separator, causing a local short circuit during the use of the battery and thus affecting the safety of the entire battery

Images