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Porous gas diffusion layer and preparation method thereof

A gas diffusion layer and diffusion hole technology, which is applied in electrical components, fuel cells, electrochemical generators, etc., can solve the problems of low porosity of porous gas diffusion layer, unfavorable gas diffusion, and low performance of metal-air batteries, so as to promote The process of commercialization, the preparation method is simple, and the effect of solving the sharp decline

Inactive Publication Date: 2015-07-15
NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] In view of the above problems, the object of the present invention is to provide a method for preparing a porous gas diffusion layer of an air cathode of a metal-air battery, so as to solve the problem that the porous gas diffusion layer of an air cathode prepared by the existing method has a relatively low porosity, which is not conducive to gas Diffusion, a problem that makes metal-air batteries lower performance

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  • Porous gas diffusion layer and preparation method thereof
  • Porous gas diffusion layer and preparation method thereof
  • Porous gas diffusion layer and preparation method thereof

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preparation example Construction

[0013] The embodiment of the present invention provides a method for preparing a porous gas diffusion layer of an air cathode of a metal-air battery, which includes the following steps:

[0014] Step S1: adding a pore former to the polytetrafluoroethylene (PTFE) emulsion to form a PTFE composite emulsion. The pore forming agent includes silicon oxide, calcium carbonate, aluminum oxide, titanium oxide or polystyrene microspheres. The particle size of the pore former is 0.05 μm-10 μm, and the particle size of the preferred pore former is 0.5 μm-5 μm. When the particle size of the pore former is larger than 10 μm, the pore size in PTFE is too large, which is not conducive to waterproofing. When the particle size of the pore former is smaller than 0.05 μm, the pore size in PTFE is too small, so that the PTFE The air permeability performance becomes worse.

[0015] The mass concentration of PTFE in the PTFE aqueous emulsion is 10%-60%, and the mass ratio of the pore former to the PTFE...

Embodiment 1 2

[0027] Example 1 Silica is used as a pore former to prepare a porous gas diffusion layer

[0028] Choose a thickness of 4mm and a bulk density of 0.137g / cm 3 Conductive graphite felt, 30Wt.% PTFE solution and silica pore former with a particle size of 2μm as raw materials for the preparation of the porous gas diffusion layer;

[0029] The silica pore former with an average particle size of 2 μm is mixed with a 30 wt% PTFE solution, and then a composite emulsion is obtained by ultrasonic dispersion; wherein the mass percentage of the pore former and PTFE is 1:5 by mass percentage.

[0030] The composite emulsion is coated on the conductive support by two-step dipping to form a coated modified conductive support with a PTFE content of 60 wt.%. The coating modified conductive support is naturally dried at room temperature, and then fired at 350° C. for 60 minutes, and then processed at a pressure of 8 MPa.

[0031] Then the sintered coating modified conductive support is immersed and etc...

Embodiment 2 2

[0032] Example 2 Silica is used as a pore former to prepare a porous gas diffusion layer

[0033] Choose a thickness of 6mm and a bulk density of 0.095g / cm 3 Conductive carbon fiber felt, 40Wt% PTFE solution and silica pore former with a particle size of 2.5μm are used as raw materials for the preparation of the porous gas diffusion layer;

[0034] The silica pore former with an average particle size of 2.5 μm is mixed with a 40 wt% PTFE solution, and then a composite emulsion suitable for application is obtained by mechanical stirring. Among them, calculated by mass percentage, the mass percentage of pore former and PTFE is 1:1.

[0035] The composite emulsion is sprayed on the conductive support to form a coating modified conductive support with a PTFE content of 55wt.%. Dry the above-mentioned coated modified conductive support at 50°C, then fire it at 330°C for 30 minutes, and then treat it under a pressure of 10MPa.

[0036] Then the sintered coating modified conductive support ...

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Abstract

The invention provides a preparation method of a porous gas diffusion layer. The preparation method comprises the following steps: adding a pore forming agent into PTFE emulsion to obtain PTFE composite emulsion; loading the composite emulsion onto a conductive supporter to form a coating-modified conductive supporter; sintering the coating-modified conductive supporter; and soaking the sintered coating-modified conductive supporter in a pore-forming-agent-removing agent to etch off the pore forming agent so as to obtain the porous gas diffusion layer with a porous structure. The invention further provides a porous gas diffusion layer. In the provided porous gas diffusion layer, a three-dimensional channel structure is formed in PTFE through a technical design, and thus the gas diffusion resistance is reduced. The provided porous gas diffusion layer can prominently improve the performance of a metal-air battery under a high power (namely high current discharge) condition.

Description

Technical field [0001] The present invention relates to the technical field of metal-air batteries, in particular to a porous gas diffusion layer used for air cathodes of metal-air batteries and a preparation method thereof. Background technique [0002] The current global energy supply is becoming increasingly scarce, and people are exploring new energy sources. As a new technology for efficient, clean, and energy utilization, fuel cells have become a hot spot in the world's energy field. Metal-air batteries take advantage of the advantages of fuel cells, using oxygen in the air as the anode active material, and metal M (zinc, aluminum, lithium, etc.) as the cathode active material. The oxygen in the air can continuously pass through the gas diffusion electrode to reach the electrochemical reaction. The interface reacts with metal M (zinc, aluminum, lithium, etc.) to release electrical energy. And because metal-air batteries have abundant raw materials, high cost performance an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01M4/88H01M4/86H01M8/02H01M8/0245
CPCH01M4/8807H01M8/0245H01M8/0247Y02E60/50
Inventor 薛业建刘兆平苗鹤王勤孙珊珊李世华
Owner NINGBO INST OF MATERIALS TECH & ENG CHINESE ACADEMY OF SCI
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