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Polyolefin microporous membrane preparation method and device

A polyolefin microporous membrane and a technology for preparing a device, which are applied in structural parts, electrical components, battery pack parts, etc., can solve the problems of low pore tortuosity, reduced cycle life, large pore size, etc., and achieve high tortuosity and uniformity. The effect of good performance and high pressure resistance

Active Publication Date: 2019-05-28
SHENZHEN ZHONGXING NEW MATERIAL TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the longitudinal stretching of the dry method, the lamellae are separated and a large number of microfibers appear, which in turn produces a slit-like pore network structure, which is prone to a certain number of through holes, and the tortuosity of the holes is extremely low. At the same time, due to the influence of the molding equipment, The pore size is generally large, which will eventually lead to a micro-short circuit in the battery, resulting in a decrease in battery capacity and cycle life

Method used

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  • Polyolefin microporous membrane preparation method and device
  • Polyolefin microporous membrane preparation method and device
  • Polyolefin microporous membrane preparation method and device

Examples

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preparation example Construction

[0031] First of all, the present invention provides a method for preparing polyolefin microporous membrane, which includes: extruding two or more materials through two or more extruders to form a melt; introducing the above melt into a multi-layer distributor for layering and stacking forming a composite multi-layer melt; extruding the above-mentioned composite multi-layer melt through a die head; forming and annealing through cooling roll casting; and then performing uniaxial stretching to form holes to obtain a multi-layer polyolefin microporous film.

[0032] In a preferred embodiment, there are two kinds of materials, which can be selected from polypropylene (PP) or polyethylene (PE) of the same grade or different grades. Correspondingly, two extruders are used to extrude two kind of material. Polypropylene and / or polyethylene can not be specially limited, yet in preferred embodiment, the melting index of polypropylene is 0.5~6.0g / 10min, and weight average molecular weight...

Embodiment 1

[0047] (1) Tape extrusion: Two extruders extrude A and B materials respectively. After plasticizing and melting, they are extruded into a 5-layer distributor and converged. The processing temperature is 230°C.

[0048] (2) Multi-layer distributor: The two kinds of materials A and B enter into the 5-layer distributor, after layering and stacking, they flow into the die head together, and the processing temperature is 220°C.

[0049] (3) Cast sheet forming: Extrude the composite two-layer melt from the die, pass through the cooling roll to form the sheet, and pull it to form a film. The temperature of the cooling roll is 90°C.

[0050] (4) Annealing and crystallization: put the multilayer cast film into an oven for heat treatment, the annealing temperature is 140°C, and the annealing time is 14h.

[0051] (5) Stretching to form holes: Stretch the annealed cast film with a stretching speed ratio of 2.5, a stretching temperature of 150°C, and a stretching speed of 4m / min to prepar...

Embodiment 2

[0053] The difference from Example 1 is that the multi-layer dispenser is a 7-layer dispenser, and a 7-layer co-extruded polyolefin microporous film is prepared, and the product properties are shown in Table 1.

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Abstract

The invention discloses a preparation method and device of a polyolefin microporous membrane. The method comprises the following steps: extruding more than two materials by more than two extruders toform a melt; introducing the melt into a multi-layer distributor for layered superposition to form a composite multi-layer melt; extruding the composite multilayer melt through a die head; performingcooling roller sheet casting forming and annealing treatment; and performing one-way stretching pore forming to obtain the multilayer polyolefin microporous membrane. According to the invention, microshort circuit of the polyolefin microporous membrane in the battery can be avoided, and the battery capacity retention and cycle performance are improved.

Description

technical field [0001] The invention relates to the technical field of polymer membrane materials, in particular to a preparation method and device for polyolefin microporous membranes. Background technique [0002] Lithium-ion batteries are composed of positive and negative electrode materials, electrolyte, diaphragm and battery casing. The diaphragm is one of the core components, and its main function is manifested in two aspects: (1) to isolate the positive and negative electrodes, which is an electronic insulator and prevents positive and negative electrodes from being separated. (2) Allow ions to pass freely and transport electrons. Therefore, the microporous structure of the separator has a crucial impact on the battery capacity, cycle performance, and rate performance. [0003] At present, lithium-ion battery separators are mainly polyolefin microporous membranes. Common preparation methods include dry method (melt stretching method) and wet method (thermally induced...

Claims

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Application Information

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IPC IPC(8): H01M2/14H01M2/16H01M10/0525H01M50/403H01M50/417H01M50/491
CPCY02E60/10
Inventor 陈官茂姚坤王哲
Owner SHENZHEN ZHONGXING NEW MATERIAL TECH CO LTD