Preparation method of large-rate discharge porous diaphragm material and application of material

A technology of porous diaphragm and porous film, applied in the field of membrane materials, can solve the problems of low open porosity, unfavorable electrolyte full penetration, low electrolyte holding capacity, etc., and achieves the effect of increasing the holding capacity and enhancing the high-rate discharge performance.

Inactive Publication Date: 2013-06-12
SHANGHAI ADVANCED RES INST CHINESE ACADEMY OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The casting solution not only forms a porous layer on the support surface, but also penetrates into the pores of the support layer. The prepared membrane has low porosity, low capacity for electrolyte solution, and high ion conduction resistance.
In addition, there is a dense skin layer on the surface of the membrane, and the porosity is low, which is not conducive to the full penetration of the electrolyte.
Moreover, the discharge performance of this type of separator is not substantially improved compared with commercial separators.
Therefore, the application of this type of separator in lithium / air batteries is limited

Method used

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  • Preparation method of large-rate discharge porous diaphragm material and application of material
  • Preparation method of large-rate discharge porous diaphragm material and application of material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0070] Prepare a homogeneous and clear casting solution as follows: Dissolve 15g PVDF and 8.5g glycerol in 76.5g NMP, heat at 45°C, stir at 120r / min for 12h, until uniform and clear, seal and vacuum defoam, After standing for 6 hours, scrape the obtained homogeneous casting solution evenly on the glass plate at ambient temperature (25±2)°C and humidity (55±10)% to form a nascent film, and then immerse it in 45° The film is solidified in the gel bath of C, the porosity of the prepared film is 80%, the bubble point pore size is 0.106 μm, and the average pore size is 0.0259 μm. LiPF 6 (EC:DMC=1:1) is the electrolyte, which is discharged at a high rate in the lithium / air battery, and the current density i=5mA / cm 2 Below, the average first discharge time is 135s.

Embodiment 2

[0072] Dissolve 18g of PVDF-HFP and 15g of polyethylene glycol 200 in 67g of DMF, heat and stir at 65°C for 12h, until it reaches a uniform and clear state, seal it for vacuum defoaming, and let it stand for 6h. Temperature (25±2)°C, humidity (55±10)%, use a 100-400μm scraper to scrape on a glass plate to form a nascent eco-film, pre-evaporate in the air for 10s-3min, and place in a 40-90°C oven 2-24h. The prepared membrane has a porosity of 73-89%, a bubble point pore size of 0.106-0.137μm, and uses LiPF 6 (EC:DMC=1:1) is the electrolyte, which is discharged at a high rate in the lithium / air battery, and the current density i=5mA / cm 2 Under normal circumstances, the average first discharge time is 110-177s. Its topography is as figure 2 -A shown.

Embodiment 3

[0074] As described in Example 2, argon atmosphere is used for plasma treatment, the treatment power is 400w, the treatment time is 1min-15min, the treatment temperature is 40-90°C, and the bubble point aperture of the prepared porous membrane is 0.1μm-3.7μm, The average pore size can be controlled within 0.07μm-2.5μm, using commonly used LiFP 6 (EC:DMC=1:1) is soaked in the electrolyte for 12 hours, and the carbon paper material coated with the mixture of carbon material and PTFE emulsion is used as the air electrode material. The Swagelok-type mold with a hollow end is a battery model, which is assembled into a lithium / air battery under air-isolated conditions, and then subjected to a high-rate discharge test with a current density of i=5mA / cm 2 Next, the first discharge time is 167-240s. Its topography is as figure 2 -B (average pore size is 1.19 μm).

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Abstract

The invention relates to the film material field, and especially relates to a preparation method of a large-rate discharge porous diaphragm material and an application of the material. The preparation method of the large-rate discharge porous diaphragm material comprises the following steps: preparing a porous film through utilizing polyvinylidene fluoride (PVDF) or poly(vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) by adopting an immersion precipitation method or a thermotropic phase separation method; and carrying out post-treatment of the surface of the prepared PVDF or PVDF-HFP porous film through an ion technology to form a nano-micro hole controllable high-hole-ratio porous diaphragm having fingerlike tunnels penetrating to the bottom. The morphology of the porous film prepared in the invention is composed of a uniform nano / micro hole surface layer, thumb-like tunnels and a sponge hole bottom layer, and the porous film having the above structure provides an enough space for accommodating an electrolyte, so the tunnels are full of the electrolyte, the electrolyte and the PVDF form a gel electrolyte in a largest area mode, and the accommodating capability of the porous diaphragm to the electrolyte is increased.

Description

technical field [0001] The invention relates to the field of membrane materials, in particular to a preparation method and application of a large-rate discharge porous diaphragm material. Background technique [0002] As an environmentally friendly new battery system, lithium / air battery has a very high theoretical energy density (11140Whkg -1 ), and has the characteristics of low price and environmental friendliness, and has extremely broad application prospects in the fields of mobile power supplies such as aerospace, portable consumer electronics, and electric vehicles. Therefore, it has aroused widespread interest in the research field in recent years, but currently lithium / air batteries are still in their infancy. Among them, catalysts and electrolyte systems (including organic solvents, ionic liquids and diaphragm materials) are two research hotspots, but lithium / air batteries Special diaphragm materials have not been seen in the market, and most researchers explore w...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/36C08J9/00C08J9/28C08J9/26C08L27/16H01M2/18H01M12/06
CPCY02E60/128Y02E60/10
Inventor 殷勇何涛杨辉李媛李雪梅宋健峰赵宝龙王周为
Owner SHANGHAI ADVANCED RES INST CHINESE ACADEMY OF SCI
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