A carbon fiber mat and a method for manufacturing the same

Abstract

The embodiment of the specification discloses a carbon fiber felt and a preparation method thereof. The preparation method of the carbon fiber felt comprises: performing impregnation treatment and rolling treatment on each of at least two carbon fiber pre-oxidized yarn felt preforms, wherein the bulk densities of the at least two carbon fiber pre-oxidized yarn felt preforms are not equal; stacking the at least two carbon fiber pre-oxidized yarn felt preforms after the rolling treatment; and performing treatment on the stacked at least two carbon fiber pre-oxidized yarn felt preforms to obtain the carbon fiber felt.

Description

TECHNICAL FIELD

[0001] The present specification relates to the field of batteries, and in particular to a carbon fiber felt, a preparation method thereof, and a preparation method of a gas diffusion layer prepared from the carbon fiber felt. BACKGROUND

[0002] The gas diffusion layer plays an important role in fuel cells, and is usually required to have high water vapor management capability. The base layer, as the main part of the gas diffusion layer, is usually required to have high porosity and good electrical conductivity. Therefore, it is necessary to provide a base layer with high porosity and good electrical conductivity, a preparation method thereof, and a gas diffusion layer with high water vapor management capability and a preparation method thereof. SUMMARY

[0003] One of the embodiments of the present specification provides a preparation method of a carbon fiber felt. The method comprises: performing impregnation treatment and rolling treatment on each of at least two carbon fiber pre-oxidized yarn felt preforms, wherein the bulk densities of the at least two carbon fiber pre-oxidized yarn felt preforms are not equal; stacking the at least two carbon fiber pre-oxidized yarn felt preforms after the rolling treatment; and processing the stacked at least two carbon fiber pre-oxidized yarn felt preforms to obtain the carbon fiber felt.

[0004] In some embodiments, the bulk density of the at least two carbon fiber pre-oxidized yarn felt preforms is 0.1 g / m 3 -0.5 g / m 3 The difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after the stacking is 0.1 g / m 3 -0.4 g / m 3 .

[0005] In some embodiments, the mass of the carbon fiber pre-oxidized yarn felt preform after the impregnation treatment and the rolling treatment is 6-9 times the mass of the carbon fiber pre-oxidized yarn felt preform without the impregnation treatment and the rolling treatment.

[0006] In some embodiments, the stacking of the at least two carbon fiber pre-oxidized yarn felt preforms after the rolling treatment comprises: stacking the at least two carbon fiber pre-oxidized yarn felt preforms after the rolling treatment in the order of the bulk density from small to large or from large to small.

[0007] In some embodiments, the processing comprises hot-pressing curing, carbonization, and graphitization, and the thickness of the stacked at least two carbon fiber pre-oxidized yarn felt preforms after the hot-pressing curing is 80 μm-400 μm.

[0008] One embodiment of this specification also provides a carbon fiber felt, which is prepared using the aforementioned method for preparing carbon fiber felt.

[0009] One embodiment of this specification also provides a method for preparing a battery diffusion layer. The method includes: subjecting the aforementioned carbon fiber felt to hydrophobic treatment to obtain a hydrophobic carbon fiber felt; coating a microporous layer material onto the side of the hydrophobic carbon fiber felt with a higher bulk density, and treating it to obtain a preliminary gas diffusion layer; and laser-drilling the preliminary gas diffusion layer to obtain the battery diffusion layer.

[0010] In some embodiments, the diameter of the laser-drilled hole is 10μm-100μm.

[0011] In some embodiments, the hole spacing of the laser drilling is 1mm-5mm.

[0012] One embodiment of this specification also provides a battery. The battery includes a battery diffusion layer prepared by the aforementioned method for preparing the battery diffusion layer. Attached Figure Description

[0013] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0014] Figure 1 This is a flowchart illustrating an exemplary method for preparing carbon fiber felt according to some embodiments of this specification.

[0015] Figure 2 This is a flowchart illustrating an exemplary method for preparing a battery diffusion layer according to some embodiments of this specification.

[0016] Figure 3 These are comparison diagrams of the pore size distribution of carbon fiber felts prepared according to Example 1 and Comparative Example 1, respectively.

[0017] Figure 4 These are comparison diagrams showing the pore size distribution of carbon fiber felts prepared according to Example 2 and Comparative Example 2, respectively.

[0018] Figure 5 This is a pore size distribution diagram of the carbon fiber felt prepared according to Example 3.

[0019] Figure 6 These are polarization curves of single cells assembled with gas diffusion layers obtained in Example 6, Comparative Example 6, and Comparative Example 6a.

[0020] Figure 7 These are polarization curves of single cells assembled with gas diffusion layers obtained in Example 7 and Comparative Example 7.

[0021] Figure 8 is a graph of the polarization curve of an assembled single cell of the gas diffusion layer prepared in Example 8 and Comparative Example 8. DETAILED DESCRIPTION

[0022] As used in the specification and claims, unless otherwise specified, "a," "an," "the," and / or "at least one" are used interchangeably with "one or more," or "one or more than one." Generally, the term "includes" or "including" means "comprising" or "comprises." Generally, the term "exemplary" or "for example" is used to provide examples, and is not to be construed as necessary or essential characteristics of the disclosed implementations.

[0023] Figure 1 is a flowchart of an exemplary method of making a carbon fiber felt according to some embodiments of the present disclosure. In some embodiments, the flowchart 100 can be performed automatically by a control system. For example, the flowchart 100 can be implemented by control instructions, and the control system can perform the operations of the flowchart 100 based on the control instructions. In some embodiments, the flowchart 100 can be performed semi-automatically. For example, one or more operations of the flowchart 100 can be performed manually by an operator. As shown in the flowchart 100, the method of making a carbon fiber felt can include the following steps. Figure 1

[0024] At step 110, each of the at least two carbon fiber pre-oxidized fiber felt preforms is subjected to an impregnation process and a rolling process.

[0025] In some embodiments, the method of making a carbon fiber felt can be performed automatically by a control system. For example, the method can be implemented by control instructions, and the control system can perform the operations involved in the method based on the control instructions. In some embodiments, the method of making a carbon fiber felt can be performed semi-automatically. For example, one or more operations can be performed manually by an operator.

[0026] The carbon fiber pre-oxidized fiber felt preform can refer to a polyacrylonitrile carbon fiber pre-oxidized fiber felt. In some embodiments, the carbon fiber pre-oxidized fiber felt preform can be made by needle punching or hydro-entangling, or can be made by other methods, which are not limited in the present disclosure. In some embodiments, the carbon fiber pre-oxidized fiber felt preform can be made in-house or purchased from the market.

[0027] ​The bulk density of the carbon fiber pre-oxidized filament felt preform can affect the properties (e.g., mechanical strength, gas-liquid transport performance) of the carbon fiber felt prepared therefrom. For example, if the bulk density of the carbon fiber pre-oxidized filament felt preform is too small, the bulk density of the carbon fiber felt prepared therefrom can be small, which can result in a low mechanical strength (e.g., tensile strength) of the carbon fiber felt. For another example, if the bulk density of the carbon fiber pre-oxidized filament felt preform is too large, the gas-liquid transport performance of the carbon fiber felt can be affected. Therefore, in some embodiments, in order to obtain a carbon fiber felt with better properties (e.g., higher tensile strength and better gas-liquid transport performance), the bulk density of the carbon fiber pre-oxidized filament felt preform needs to satisfy a predetermined condition.

[0028] In some embodiments, the bulk density of the carbon fiber pre-oxidized filament felt preform can be in the range of 0.1 g / m 3 -0.5 g / m 3 In some embodiments, the bulk density of the carbon fiber pre-oxidized filament felt preform can be in the range of 0.15 g / m 3 -0.45 g / m 3 In some embodiments, the bulk density of the carbon fiber pre-oxidized filament felt preform can be in the range of 0.2 g / m 3 -0.4 g / m 3 In some embodiments, the bulk density of the carbon fiber pre-oxidized filament felt preform can be in the range of 0.25 g / m 3 -0.35 g / m 3 In some embodiments, the bulk density of the carbon fiber pre-oxidized filament felt preform can be in the range of 0.28 g / m 3 -0.3 g / m 3 .

[0029] In some embodiments, the carbon fiber felt is prepared by using at least two carbon fiber pre-oxidized filament felt preforms, and the bulk density of the at least two carbon fiber pre-oxidized filament felt preforms can be different, so as to obtain a carbon fiber felt with a clear gradient pore structure. For example, the bulk density of the first carbon fiber pre-oxidized filament felt preform is 0.1 g / m 3 , and the bulk density of the second carbon fiber pre-oxidized filament felt preform is 0.15 g / m 3 . The difference between the bulk densities of the two carbon fiber pre-oxidized filament felt preforms is 0.05 g / m 3 .

[0030] In some embodiments, each carbon fiber pre-oxidized filament felt preform can include at least one carbon fiber pre-oxidized filament felt preform. In some embodiments, the bulk density of each carbon fiber pre-oxidized filament felt preform can be equal. In some embodiments, the bulk density of each carbon fiber pre-oxidized filament felt preform can be unequal. For example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be within a preset range (e.g., 0.01 g / m2to 0.1 g / m2). For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 3 -0.1 g / m2 3 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform.

[0031] The areal density of the carbon fiber pre-oxidized filament felt preform can affect the performance (e.g., mechanical strength, gas-liquid transport performance) and production cost of the carbon fiber felt. For example, if the areal density of the carbon fiber pre-oxidized filament felt preform is too small, the areal density of the carbon fiber felt prepared therefrom can be small, which can result in low mechanical strength (e.g., tensile strength) of the carbon fiber felt. For another example, if the areal density of the carbon fiber pre-oxidized filament felt preform is too large, the production cost of the carbon fiber felt can be increased, and the gas-liquid transport performance of the carbon fiber felt can be affected. Therefore, in some embodiments, in order to make the carbon fiber felt have better performance (e.g., higher tensile strength and better gas-liquid transport performance) and lower production cost, the areal density of the carbon fiber pre-oxidized filament felt preform needs to satisfy a preset condition.

[0032] In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 10 g / m2to 60 g / m2. In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 15 g / m2to 55 g / m2. In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 20 g / m2to 50 g / m2. In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 25 g / m2to 45 g / m2. In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 30 g / m2to 40 g / m2. In some embodiments, the areal density of the carbon fiber pre-oxidized filament felt preform can be within a range from 35 g / m2to 38 g / m2. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform. 2 -0.1 g / m2 2 For another example, the difference of the bulk density of different carbon fiber pre-oxidized filament felt preforms in the same carbon fiber pre-oxidized filament felt preform can be a preset percentage (e.g., 1% to 10%) of the bulk density of any one carbon fiber pre-oxidized filament felt preform.

[0033] In some embodiments, the areal densities of the at least two carbon fiber pre-oxidized filament felt preforms can be equal or unequal. In some embodiments, the surface areas of the at least two carbon fiber pre-oxidized filament felt preforms can be equal to save the cutting process during subsequent layering. In some embodiments, the thicknesses of the at least two carbon fiber pre-oxidized filament felt preforms can be equal or unequal.

[0034] In some embodiments, the carbon fiber pre-oxidized filament felt preforms can be fully immersed in the impregnation liquid during the impregnation process. In some embodiments, the impregnation liquid can be reused to save cost. In some embodiments, the at least two carbon fiber pre-oxidized filament felt preforms can be impregnated in the same or different impregnation liquid. In some embodiments, different carbon fiber pre-oxidized filament felt preforms in each of the at least two carbon fiber pre-oxidized filament felt preforms can be impregnated in the same or different impregnation liquid.

[0035] In some embodiments, the impregnation liquid can include a thermosetting resin as a binder and a densification agent. In some embodiments, the thermosetting resin can include, but is not limited to, at least one of a phenolic resin, an epoxy resin, a furan resin, or a furfural resin.

[0036] In some embodiments, the thermosetting resin can account for 0.5wt%-20wt% of the impregnation liquid. In some embodiments, the thermosetting resin can account for 1wt%-15wt% of the impregnation liquid. In some embodiments, the thermosetting resin can account for 2wt%-10wt% of the impregnation liquid. In some embodiments, the thermosetting resin can account for 2wt%-5wt% of the impregnation liquid.

[0037] In some embodiments, the impregnation liquid can further include an alcohol. In some embodiments, the alcohol can serve as a solvent to improve the wettability of the impregnation liquid to the carbon fiber pre-oxidized filament felt preforms, and further reduce the impregnation time of the carbon fiber pre-oxidized filament felt preforms in the impregnation liquid.

[0038] In some embodiments, the alcohol can include, but is not limited to, at least one of ethanol, ethylene glycol, propanol, glycerol, isopropanol, and the like.

[0039] In some embodiments, immersing each of the at least two carbon fiber pre-oxidized filament felt preforms in the impregnation liquid for a predetermined time can enable each of the at least two carbon fiber pre-oxidized filament felt preforms to adsorb the thermosetting resin, so as to facilitate subsequent carbonization and graphitization processes and further improve the performance of the carbon fiber felt (e.g., reduce the resistivity).

[0040] In some embodiments, each of the at least two impregnated carbon fiber pre-oxidized filament mat preforms can be subjected to a rolling treatment to remove excess thermosetting resin in the impregnated carbon fiber pre-oxidized filament mat preform, which can avoid splashing of thermosetting resin due to stress extrusion during subsequent hot-pressing and curing treatment, resulting in loss. In some embodiments, the removed thermosetting resin during the rolling treatment can be collected and reused, which can further reduce production costs. In some embodiments, the rolling treatment can make the thermosetting resin more uniformly distributed in each carbon fiber pre-oxidized filament mat preform or each carbon fiber pre-oxidized filament mat preform, which can further improve the performance of the carbon fiber mat. In some embodiments, the rolling treatment can be sequentially performed on each of the at least two impregnated carbon fiber pre-oxidized filament mat preforms, or can be simultaneously performed on the at least two impregnated carbon fiber pre-oxidized filament mat preforms. In some embodiments, the rolling treatment can be sequentially performed on each of the carbon fiber pre-oxidized filament mat preforms in each of the at least two impregnated carbon fiber pre-oxidized filament mat preforms, or can be simultaneously performed on the carbon fiber pre-oxidized filament mat preforms in each of the at least two impregnated carbon fiber pre-oxidized filament mat preforms.

[0041] In some embodiments, the mass gain of the carbon fiber pre-oxidized filament mat preform after the rolling treatment can be controlled by controlling the relevant process parameters of the rolling treatment (e.g., rolling gap, rolling pressure, etc.).

[0042] The mass gain of the carbon fiber pre-oxidized filament mat preform after the impregnation treatment and the rolling treatment can affect the performance of the carbon fiber mat. For example, if the mass gain of the carbon fiber pre-oxidized filament mat preform after the impregnation treatment and the rolling treatment is too small, the thermosetting resin at the contact interface between adjacent carbon fiber pre-oxidized filament mat preforms after lamination can be less, which can result in lower mechanical strength of the prepared carbon fiber mat. For another example, if the mass gain of the carbon fiber pre-oxidized filament mat preform after the impregnation treatment and the rolling treatment is too large, the thermosetting resin at the contact interface between adjacent carbon fiber pre-oxidized filament mat preforms after lamination can be unevenly distributed or aggregated. Moreover, part of the thermosetting resin can block the pores of the carbon fiber pre-oxidized filament mat preform, which can further result in lower porosity and poorer bending performance of the carbon fiber mat. Therefore, in some embodiments, in order to make the carbon fiber mat have better performance, the mass gain of the carbon fiber pre-oxidized filament mat preform after the impregnation treatment and the rolling treatment needs to meet a predetermined condition.

[0043] In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 6-9 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 6.2-8.8 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 6.4-8.6 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 6.6-8.4 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 6.8-8.2 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 7-8 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 7.2-7.8 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment. In some embodiments, the mass of the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is 7.4-7.6 times the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment.

[0044] Step 120, stacking the at least two carbon fiber pre-oxidized filament felt preforms after the rolling treatment.

[0045] In some embodiments, the at least two carbon fiber pre-oxidized filament felt preforms after the rolling treatment can be stacked in order of the bulk density from small to large or from large to small, so that the prepared carbon fiber felt has a gradient pore structure.

[0046] The difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination affects the performance of the carbon fiber felt prepared. For example, if the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination is too small, the prepared carbon fiber felt will not have a clear gradient structure of the pores, which will affect the performance of the battery. For another example, if the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination is too large, the battery assembled from the prepared carbon fiber felt will have poor drainage performance and be prone to flooding. Therefore, in some embodiments, in order to make the prepared carbon fiber felt have a reasonable gradient pore structure, or the battery assembled from the prepared carbon fiber felt have a better performance (for example, better drainage performance), the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination needs to meet a predetermined condition.

[0047] In some embodiments, the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination can be 0.1 g / m 3 -0.4 g / m 3 In some embodiments, the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination can be 0.15 g / m 3 -0.35 g / m 3 In some embodiments, the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination can be 0.2 g / m 3 -0.3 g / m 3 In some embodiments, the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination can be 0.22 g / m 3 -0.25 g / m 3 In some embodiments, the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized yarn felt preforms after lamination can be 0.1 g / m 3 , 0.15 g / m 3 , 0.2 g / m 3 , 0.25 g / m 3 , 0.3 g / m 3 , 0.35 g / m 3 , or 0.4 g / m 3 .

[0048] Step 130, treating the at least two carbon fiber pre-oxidized yarn felt preforms after lamination to obtain a carbon fiber felt.

[0049] In some embodiments, treating the at least two carbon fiber pre-oxidized yarn felt preforms after lamination can include hot-pressing curing, carbonization, and graphitization.

[0050] During the heat pressing and curing process of the laminated at least two carbon fiber pre-oxidized filament felt preforms, the thermosetting resin will undergo cross-linking and curing reaction to achieve densification and lapping effect between the at least two carbon fiber pre-oxidized filament felt preforms, and further can construct an electronic transmission channel in the case of difference in the pore distribution of the at least two carbon fiber pre-oxidized filament felt preforms.

[0051] The heat pressing and curing temperature and / or the heat pressing and curing pressure will affect the performance and preparation efficiency of the carbon fiber felt. For example, if the heat pressing and curing temperature and / or the heat pressing and curing pressure is too small, the heat pressing and curing efficiency will be low, further leading to low preparation efficiency of the carbon fiber felt. For another example, if the heat pressing and curing temperature and / or the heat pressing and curing pressure is too large, the thermosetting resin will have large fluidity, leading to low content of the thermosetting resin between the adjacent two carbon fiber pre-oxidized filament felt preforms, further leading to low mechanical strength of the prepared carbon fiber felt. Therefore, in some embodiments, in order to make the carbon fiber felt have better performance (for example, better mechanical strength) and higher preparation efficiency, the heat pressing and curing temperature and / or the heat pressing and curing pressure needs to meet the preset conditions.

[0052] In some embodiments, the heat pressing and curing temperature can be in the range of 150-250°C. In some embodiments, the heat pressing and curing temperature can be in the range of 170-230°C. In some embodiments, the heat pressing and curing temperature can be in the range of 190-210°C. In some embodiments, the heat pressing and curing temperature can be in the range of 200-205°C.

[0053] In some embodiments, the heat pressing and curing pressure can be in the range of 0.5-5MPa. In some embodiments, the heat pressing and curing pressure can be in the range of 1-4MPa. In some embodiments, the heat pressing and curing pressure can be in the range of 2-3MPa.

[0054] In some embodiments, the heat pressing and curing time can be in the range of 5-30min. In some embodiments, the heat pressing and curing time can be in the range of 10-25min. In some embodiments, the heat pressing and curing time can be in the range of 15-20min.

[0055] In some embodiments, the thickness of the laminated at least two carbon fiber pre-oxidized filament felt preforms after the heat pressing and curing process can be controlled by controlling the related process parameters (for example, the heat pressing and curing temperature, the heat pressing and curing pressure, the heat pressing and curing time, etc.) of the heat pressing and curing process.

[0056] The thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can affect the performance of the carbon fiber felt. For example, if the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment is too small, the gradient pore structure can not be obvious. For another example, if the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment is too large, the overlap between the at least two carbon fiber pre-oxidized filament felt preforms can be low, which can further result in a high electrical resistivity and a large electronic transport and mass transfer resistance of the carbon fiber felt. Therefore, in some embodiments, in order to make the carbon fiber felt have a better performance (e.g., a better electronic transport ability, a lower electrical resistivity and mass transfer resistance), the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment needs to meet a preset condition.

[0057] In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 80 pm to 400 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 100 pm to 380 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 120 pm to 360 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 140 pm to 340 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 160 pm to 320 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 180 pm to 300 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 200 pm to 280 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 220 pm to 260 pm. In some embodiments, the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be in a range of 230 pm to 250 pm.

[0058] In some embodiments, the at least two carbon fiber pre-oxidized filament felt preforms after the hot-pressing and curing treatment can be subjected to a carbonization treatment. In some embodiments, the carbonization treatment can be performed in an inert atmosphere. In some embodiments, the inert atmosphere can include, but is not limited to, at least one of nitrogen, an inert gas (noble gas).

[0059] In some embodiments, the carbonization temperature can be in the range of 800-1200°C. In some embodiments, the carbonization temperature can be in the range of 900-1100°C. In some embodiments, the carbonization temperature can be in the range of 950-1000°C.

[0060] In some embodiments, the carbonization time can be in the range of 10 min-2 h. In some embodiments, the carbonization time can be in the range of 30 min-1.8 h. In some embodiments, the carbonization time can be in the range of 50 min-1.5 h. In some embodiments, the carbonization time can be in the range of 1 h-1.2 h.

[0061] In some embodiments, the carbonized at least two carbon fiber pre-oxidized filament felt preforms can be subjected to graphitization treatment to obtain a carbon fiber felt. In some embodiments, the graphitization treatment can be performed under an inert atmosphere.

[0062] In some embodiments, the graphitization temperature can be in the range of 1600-2600°C. In some embodiments, the graphitization temperature can be in the range of 1700-2400°C. In some embodiments, the graphitization temperature can be in the range of 1800-2200°C. In some embodiments, the graphitization temperature can be in the range of 1900-2100°C. In some embodiments, the graphitization temperature can be in the range of 2000-2050°C.

[0063] In some embodiments, the graphitization time can be in the range of 10 min-2 h. In some embodiments, the graphitization time can be in the range of 20 min-1 h. In some embodiments, the graphitization time can be in the range of 30 min-40 min.

[0064] The carbon fiber felt prepared by the embodiments of the present specification has a gradient pore structure and can be used as a base layer of a gas diffusion layer. Compared with the preparation of a carbon fiber paper for further preparation of a gas diffusion layer by using a carbon fiber paper having a two-dimensional planar structure, the embodiments of the present specification use a carbon fiber pre-oxidized filament felt preform which does not need secondary carbonization treatment and has a three-dimensional structure to prepare a carbon fiber felt, which not only saves cost, but also makes the prepared carbon fiber felt have higher porosity and good electrical conductivity, and the battery diffusion layer prepared from the carbon fiber felt has more excellent water vapor management capability.

[0065] It should be noted that the above description of the process 100 is merely for example and illustration, and does not limit the scope of the present specification. Various modifications and changes can be made to the process 100 by those skilled in the art under the guidance of the present specification. However, these modifications and changes are still within the scope of the present specification. For example, one or more additional operations not described can be added.

[0066] Some embodiments of the present specification also provide a carbon fiber felt, which is prepared by using the aforementioned method for preparing a carbon fiber felt. For more technical details, please refer to the relevant description of the aforementioned method for preparing a carbon fiber felt, which will not be repeated here.

[0067] Figure 2 is a flowchart of an exemplary method for preparing a battery diffusion layer according to some embodiments of the present specification. In some embodiments, the flowchart 200 can be automatically executed by a control system. For example, the flowchart 200 can be implemented by control instructions, and the control system completes each operation of the flowchart 200 based on the control instructions. In some embodiments, the flowchart 200 can be semi-automatically executed. For example, one or more operations of the flowchart 200 can be manually executed by an operator. As shown in the flowchart 200, the flowchart 200 can include the following steps. Figure 2

[0068] Step 210, hydrophobic treatment is performed on the carbon fiber felt to obtain a hydrophobic carbon fiber felt.

[0069] For more technical details about the carbon fiber felt, please refer to other parts of the present specification (for example, the description of the carbon fiber felt and the related description thereof), which will not be repeated here. Figure 1

[0070] In some embodiments, the hydrophobic treatment of the carbon fiber felt can include immersing the carbon fiber felt in a hydrophobic agent for surface hydrophobic treatment. In some embodiments, the hydrophobic agent can include at least one of polytetrafluoroethylene (PTFE), perfluoroalkoxy alkenyl resin (FEP), or polyvinylidene fluoride (PVDF). In some embodiments, the method can further include drying and / or sintering treatment on the hydrophobic treated carbon fiber felt to obtain a hydrophobic carbon fiber felt with a gradient pore structure. In some embodiments, the sintering treatment can be performed at a temperature in the range of 300°C-350°C. In some embodiments, the sintering treatment can be performed for a time in the range of 1h-2h.

[0071] In some embodiments, the content of the hydrophobic agent in the hydrophobic carbon fiber felt can be in the range of 15%-25%.

[0072] Step 220, coating a microporous layer material on the side of the hydrophobic carbon fiber felt with a larger bulk density, and performing treatment to obtain a primary gas diffusion layer.

[0073] ​​In some embodiments, the microporous layer material can refer to a uniform dispersion including conductive carbon powder, carbon nanomaterial, hydrophobic agent, and solvent. In some embodiments, the conductive carbon powder can include at least one of acetylene black, conductive carbon black VXC-72(R), conductive carbon black BP2000, or ketjen black. In some embodiments, the carbon nanomaterial can include at least one of carbon nanotube, graphene oxide. In some embodiments, the hydrophobic agent can include at least one of polytetrafluoroethylene (PTFE), perfluoroalkoxy alkenyl resin (FEP), or polyvinylidene fluoride (PVDF). In some embodiments, the solvent can include, but not limited to, water, ethanol, isopropyl alcohol, glycerol, and the like.

[0074] In some embodiments, the treatment after coating the microporous layer material can include drying treatment and / or sintering treatment. In some embodiments, the temperature of the sintering treatment can be in the range of 300-350°C. In some embodiments, the time of the sintering treatment can be in the range of 1-2h.

[0075] At step 230, laser drilling is performed on the preliminary gas diffusion layer to obtain a gas diffusion layer.

[0076] In some embodiments, the aperture of the laser drilling can refer to the equivalent diameter of the hole. The hole can be a through hole. The aperture of the laser drilling can affect the performance (e.g., water vapor management ability, gas-liquid transport performance) of the obtained gas diffusion layer. For example, if the aperture of the laser drilling is too small, the water vapor management ability of the gas diffusion layer can be poor. For another example, if the aperture of the laser drilling is too large, the gas-liquid transport performance of the gas diffusion layer can be affected. Therefore, in some embodiments, in order to make the gas diffusion layer have better performance (e.g., better water vapor management ability and gas-liquid transport performance), the aperture of the laser drilling needs to meet a predetermined condition.

[0077] In some embodiments, the aperture of the laser drilling can be 10-100pm. In some embodiments, the aperture of the laser drilling can be 20-90pm. In some embodiments, the aperture of the laser drilling can be 30-80pm. In some embodiments, the aperture of the laser drilling can be 40-70pm. In some embodiments, the aperture of the laser drilling can be 50-60pm. In some embodiments, the aperture of the laser drilling can be 10pm, 20pm, 30pm, 40pm, 50pm, 60pm, 70pm, 80pm, 90pm, or 100pm, and the like.

[0078] In some embodiments, the pitch of the laser drilling can refer to the shortest distance between the edges of adjacent holes.

[0079] The laser-perforated hole spacing affects the performance (e.g., water vapor management capability, gas-liquid transport performance) of the prepared gas diffusion layer. For example, if the laser-perforated hole spacing is too large, the water vapor management capability of the gas diffusion layer is poor. For another example, if the laser-perforated hole spacing is too small, the electrical conductivity and mechanical properties of the gas diffusion layer are affected. Therefore, in some embodiments, in order to make the gas diffusion layer have better performance (e.g., better water vapor management capability, electrical conductivity and mechanical properties), the laser-perforated hole spacing needs to meet a predetermined condition.

[0080] In some embodiments, the laser-perforated hole spacing can be 1 mm-5 mm. In some embodiments, the laser-perforated hole spacing can be 1.5 mm-4.5 mm. In some embodiments, the laser-perforated hole spacing can be 2 mm-4 mm. In some embodiments, the laser-perforated hole spacing can be 2.5 mm-3.5 mm. In some embodiments, the laser-perforated hole spacing can be 2 mm-3 mm. In some embodiments, the laser-perforated hole spacing can be 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm or 5 mm.

[0081] The embodiments of the present specification can improve the water vapor management capability of the gas diffusion layer by using a carbon fiber felt with a gradient pore structure as a substrate layer, and forming a hole structure with a specific size (pore diameter of 10 μm-100 μm, hole spacing of 1 mm-5 mm) on the gas diffusion layer by laser perforation.

[0082] It should be noted that the above description of the process 200 is merely for example and illustration, and does not limit the scope of the present specification. Those skilled in the art can make various modifications and changes to the process 200 under the guidance of the present specification. However, these modifications and changes are still within the scope of the present specification. For example, one or more additional operations not described can be added.

[0083] Some embodiments of the present specification also provide a battery including a battery diffusion layer prepared using the preparation method of the aforementioned battery diffusion layer. For more technical details, please refer to the related description of the aforementioned preparation method of the battery diffusion layer, which will not be repeated here.

[0084] Example 1

[0085] A carbon fiber pre-oxidized filament felt preform A with an area density of 20 g / m 2 and a bulk density of 0.18 g / cm 3 and a carbon fiber pre-oxidized filament felt preform B with an area density of 45 g / m 2 and a bulk density of 0.45 g / cm 3The carbon fiber pre-oxidized filament felt preform B was dipped in a phenolic resin solution with a phenolic resin content of 3wt% for impregnation treatment. The carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after impregnation treatment were taken out and were respectively subjected to rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform A after impregnation treatment and rolling treatment was 6.50 times the mass of the carbon fiber pre-oxidized filament felt preform A without impregnation treatment and rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform B after impregnation treatment and rolling treatment was 6.54 times the mass of the carbon fiber pre-oxidized filament felt preform B without impregnation treatment and rolling treatment. The carbon fiber pre-oxidized filament felt preform A after rolling treatment was placed at the bottom layer, and the carbon fiber pre-oxidized filament felt preform B after rolling treatment was placed on the upper layer of the carbon fiber pre-oxidized filament felt preform A after rolling treatment. The laminated carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B were subjected to hot-pressing and curing treatment at 240 filaments and 1 MPa for 30 min, to obtain a laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B with a thickness of 160 μm. The laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B was subjected to carbonization treatment at 1000 °C for 2 h under an inert atmosphere. Then, graphitization treatment was performed at 2200 °C for 2 h. A carbon fiber felt with a surface density of 75 g / m 2 , an average volume resistivity of 8.63 mΩ·cm was prepared.

[0086] Comparative Example 1

[0087] The difference from Example 1 is that the carbon fiber pre-oxidized filament felt preform A with a surface density of 20 g / m 2 , a bulk density of 0.18 g / cm 3 and the carbon fiber pre-oxidized filament felt preform B with a surface density of 45 g / m 2 , a bulk density of 0.45 g / cm 3 were replaced by one carbon fiber pre-oxidized filament felt preform with a surface density of 60 g / m 2 , a bulk density of 0.31 g / cm 3 . The mass of the carbon fiber pre-oxidized filament felt preform after impregnation treatment and rolling treatment was 6.60 times the mass of the carbon fiber pre-oxidized filament felt preform without impregnation treatment and rolling treatment. A carbon fiber felt with a surface density of 75 g / m 2 , an average volume resistivity of 9.02 mΩ·cm was prepared.

[0088] Figure 3 is a pore size distribution comparison chart of the carbon fiber felts prepared according to Example 1 and Comparative Example 1, respectively. From the chart, it can be seen that the carbon fiber felt prepared according to Example 1 has a smaller pore size than the carbon fiber felt prepared according to Comparative Example 1. Figure 3It can be seen that the carbon fiber felt prepared in Example 1 has a wider pore distribution than Comparative Example 1, and a large number of pore structures are distributed at pore diameters of 20 μm, 25 μm, 40 μm, 50 μm, 60 μm, 80 μm and 120 μm, indicating that the carbon fiber felt has a gradient pore structure.

[0089] Comparative Example 1a

[0090] The difference from Example 1 is that the mass of the carbon fiber pre-oxidized filament felt preform A after the impregnation treatment and the rolling treatment is 4.20 times the mass of the carbon fiber pre-oxidized filament felt preform A without the impregnation treatment and the rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform B after the impregnation treatment and the rolling treatment is 4.20 times the mass of the carbon fiber pre-oxidized filament felt preform B without the impregnation treatment and the rolling treatment. A carbon fiber felt with a surface density of 78 g / m 2 is prepared, but it is easy to delaminate and fall off.

[0091] Comparative Example 1b

[0092] The difference from Example 1 is that the mass of the carbon fiber pre-oxidized filament felt preform A after the impregnation treatment and the rolling treatment is 10.20 times the mass of the carbon fiber pre-oxidized filament felt preform A without the impregnation treatment and the rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform B after the impregnation treatment and the rolling treatment is 10.40 times the mass of the carbon fiber pre-oxidized filament felt preform B without the impregnation treatment and the rolling treatment. A carbon fiber felt with a surface density of 95 g / m 2 is prepared, but its porosity is 71%, which does not meet the standard (the porosity needs to be not less than 75%) of the substrate layer for the gas diffusion layer.

[0093] Comparative Example 1c

[0094] The difference from Example 1 is that the carbon fiber raw paper A and the carbon fiber raw paper B with the same bulk density and surface density are used to replace the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B. A carbon fiber paper with a surface density of 75 g / m 2 and an average volume resistivity of 9.02 mΩ·cm is prepared. The carbon fiber paper has pore structures distributed at pore diameters of 30 μm, 40 μm, 50 μm, 60 μm, 100 μm and 120 μm. However, compared with the carbon fiber pre-oxidized felt which is only carbonized once after impregnation of the resin, the carbon fibers in the carbon fiber raw paper undergo a second carbonization after impregnation of the resin, which will cause a certain waste of energy.

[0095] The performance comparison of the above Example 1, Comparative Example 1, Comparative Examples 1a-1c is shown in Table 1.

[0096] Table 1 Performance Comparison Table of Example 1, Comparative Example 1, Comparative Examples 1a-1c

[0097]

[0098]

[0099] It can be seen from other embodiments of the present specification and Table 1 that the carbon fiber pre-oxidized filament felt preform after the impregnation treatment and the rolling treatment is controlled within the preset multiple range (6 times to 9 times) of the mass of the carbon fiber pre-oxidized filament felt preform without the impregnation treatment and the rolling treatment, and the carbon fiber felt with better performance (for example, the porosity is not less than 75%) can be prepared.

[0100] Example 2

[0101] The carbon fiber pre-oxidized filament felt preform A with the area density of 20 g / m 2 , the bulk density of 0.10 g / cm 3 , the carbon fiber pre-oxidized filament felt preform B with the area density of 30 g / m 2 , the bulk density of 0.20 g / cm 3 , and the carbon fiber pre-oxidized filament felt preform C with the area density of 50 g / m 2 , the bulk density of 0.45 g / cm 3 were respectively impregnated in the phenolic resin solution with the phenolic resin content of 7.5 wt% for the impregnation treatment. The carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C after the impregnation treatment were taken out and respectively subjected to the rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform A, the mass of the carbon fiber pre-oxidized filament felt preform B and the mass of the carbon fiber pre-oxidized filament felt preform C after the impregnation treatment and the rolling treatment were respectively 7.50 times, 7.54 times and 7.52 times of the mass of the carbon fiber pre-oxidized filament felt preform A, the mass of the carbon fiber pre-oxidized filament felt preform B and the mass of the carbon fiber pre-oxidized filament felt preform C without the impregnation treatment and the rolling treatment. The carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C after the rolling treatment were stacked in the order of the bulk density from small to large, that is, A was placed in the bottom layer, C was placed in the uppermost layer, and B was placed between A and C. The stacked carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C were subjected to the heat pressing and curing treatment at 250℃, 0.5 MPa for 15 min to obtain the stacked body of the carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C with the thickness of 400 μm. The stacked body was subjected to the carbonization treatment at 1200℃ for 0.5 h under the inert atmosphere. Then, the stacked body was subjected to the graphitization treatment at 2200℃ for 0.5 h. The carbon fiber felt with the area density of 95 g / m 2, and the average volume resistivity of the carbon fiber felt is 28.81 mΩ·cm.

[0102] Comparative Example 2

[0103] The difference from Example 2 is that the carbon fiber pre-oxidized filament felt preform A with an area density of 20 g / m 2 , a bulk density of 0.10 g / cm 3 , the carbon fiber pre-oxidized filament felt preform B with an area density of 30 g / m 2 , a bulk density of 0.20 g / cm 3 , and the carbon fiber pre-oxidized filament felt preform C with an area density of 50 g / m 2 , a bulk density of 0.45 g / cm 3 are replaced by one carbon fiber pre-oxidized filament felt preform with an area density of 95 g / m 2 , a bulk density of 0.25 g / cm 3 . The mass of the carbon fiber pre-oxidized filament felt preform after impregnation treatment and rolling treatment is 7.55 times the mass of the carbon fiber pre-oxidized filament felt preform without impregnation treatment and rolling treatment. The carbon fiber felt with an area density of 95 g / m 2 , an average volume resistivity of 25.45 mΩ·cm is prepared.

[0104] Figure 4 is a pore size distribution comparison diagram of the carbon fiber felt prepared according to Example 2 and Comparative Example 2, respectively. It can be seen from Figure 4 that, compared with Comparative Example 2, the carbon fiber felt prepared in Example 2 has a wider pore distribution, and a large number of pore structures are distributed at pore diameters of 11 μm, 30 μm, 35 μm, 50 μm, 80 μm, 110 μm and 190 μm, indicating that the carbon fiber felt has a gradient pore structure.

[0105] Comparative Example 2a

[0106] The difference from Example 2 is that the thickness of the laminated body of the carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C after heat pressing and curing treatment is controlled to be 460 μm. The carbon fiber felt with an area density of 115 g / m 2 , an average volume resistivity of 35.60 mΩ·cm is prepared. Due to the larger thickness, the ohmic polarization of the carbon fiber felt increases.

[0107] Comparative Example 2b

[0108] The difference from Example 2 is that the bulk densities of the carbon fiber pre-oxidized filament felt preform A, the carbon fiber pre-oxidized filament felt preform B and the carbon fiber pre-oxidized filament felt preform C are 0.15 g / cm 3 and 0.45 g / cm 3Example 2, Comparative Example 2, Comparative Examples 2a-2b, and the thickness of the laminated carbon fiber pre-oxidized filament felt pre-forms A and B after the heat-pressing and curing treatment was controlled to be 60 μm. A carbon fiber felt with a surface density of 85 g / m 2 was prepared. However, the porosity thereof was 65%, which did not meet the standard for the base layer of the gas diffusion layer (the porosity needs to be no less than 75%).

[0109] The performance comparison of the above-mentioned Example 2, Comparative Example 2, Comparative Examples 2a-2b is shown in Table 2.

[0110] Table 2 Performance comparison table of Example 2, Comparative Example 2, Comparative Examples 2a-2b

[0111]

[0112] As can be seen from the other embodiments and Table 2 of the present specification, the thickness of the laminated at least two carbon fiber pre-oxidized filament felt pre-forms after the heat-pressing and curing treatment is controlled within a preset range (80 μm-400 μm), and a carbon fiber felt with relatively optimal performance (for example, the porosity is no less than 75% and the relatively optimal electrical conductivity) can be prepared.

[0113] Example 3

[0114] The carbon fiber pre-oxidized filament felt pre-form A with a surface density of 10 g / m 2 and a bulk density of 0.1 g / cm 3 and the carbon fiber pre-oxidized filament felt pre-form B with a surface density of 50 g / m 2 and a bulk density of 0.5 g / cm 3 were respectively immersed in a phenolic resin solution with a phenolic resin content of 12.5 wt% for the impregnation treatment. The carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B after the impregnation treatment were taken out and were respectively subjected to the rolling treatment. The mass of the carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B after the impregnation treatment and the rolling treatment was respectively 8.10 times and 8.15 times the mass of the carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B without the impregnation treatment and the rolling treatment. The carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B after the rolling treatment were laminated. The laminated carbon fiber pre-oxidized filament pre-form A and the carbon fiber pre-oxidized filament felt pre-form B were subjected to the heat-pressing and curing treatment at 180 ℃ and 5 MPa for 5 min, and a laminated body of the carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B with a thickness of 80 μm was obtained. The laminated body of the carbon fiber pre-oxidized filament felt pre-form A and the carbon fiber pre-oxidized filament felt pre-form B was subjected to the carbonization treatment under the inert atmosphere at a temperature rising to 800 ℃ for 10 min. Then, the temperature was raised to 2000 ℃ for the graphitization treatment for 10 min. A carbon fiber felt with a surface density of 60 g / m2 , a carbon fiber felt having an average volume resistivity of 5.92 mΩ-cm.

[0115] Figure 5 is a pore size distribution diagram of the carbon fiber felt prepared according to Example 3. It can be seen from the diagram that the carbon fiber felt prepared according to Example 3 has a wide pore distribution, and a large number of pore structures are distributed at pore diameters of 13 μm, 23 μm, 33 μm, 40 μm, 45 μm, 90 μm, 120 μm and 180 μm, indicating that the carbon fiber felt has a gradient pore structure. Figure 5

[0116] Comparative Example 3a

[0117] The difference between Example 3 and Comparative Example 3a is that the bulk density of the carbon fiber pre-oxidized filament felt preform A is 0.05 g / cm 3 , and the bulk density of the carbon fiber pre-oxidized filament felt preform B is 0.7 g / cm 3 . A carbon fiber felt having a surface density of 75 g / m 2 is prepared, but it only has pores distributed at 20 μm and 120 μm, and does not have a clear gradient pore structure.

[0118] The performance comparison between Example 3 and Comparative Example 3a is shown in Table 3.

[0119] Table 3 Performance comparison between Example 3 and Comparative Example 3a

[0120] As can be seen from other examples in the specification and Table 3, when the bulk densities of the adjacent carbon fiber pre-oxidized filament felt preforms differ greatly, an effective pore gradient cannot be formed. When the bulk density of the carbon fiber pre-oxidized filament felt preform is 0.1 g / m 3 -0.5 g / m 3 , and the difference between the bulk densities of the two adjacent carbon fiber pre-oxidized filament felt preforms is within the range of 0.1 g / m 3 -0.4 g / m 3 , a carbon fiber felt having better performance (for example, better electrical conductivity) can be prepared.

[0121] Example 4

[0122] A carbon fiber pre-oxidized filament felt preform A having a surface density of 30 g / m 2 and a bulk density of 0.15 g / cm 3 , and a carbon fiber pre-oxidized filament felt preform B having a surface density of 60 g / m 2 and a bulk density of 0.44 g / cm 3 ​The carbon fiber pre-oxidized filament felt preform B is dipped in a phenolic resin solution with a phenolic resin content of 7.5 wt% for dipping treatment. The carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after dipping treatment are taken out and are respectively subjected to rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after dipping treatment and rolling treatment is respectively 7.40 times and 7.47 times of the mass of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B without dipping treatment and rolling treatment. The carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after rolling treatment are laminated. The laminated carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B are subjected to hot-pressing and curing treatment at 220℃ and 1MPa for 20min to obtain a laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B with a thickness of 250μm. The laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B is subjected to carbonization treatment at 1100℃ for 1h under an inert atmosphere. Then, the laminated body is subjected to graphitization treatment at 1900℃ for 1h. A carbon fiber felt with a surface density of 80g / m 2 , an average volume resistivity of 17.41mΩ·cm, a large amount of pore structures distributed at pore diameters of 15μm, 25μm, 33μm, 45μm, 90μm and 120μm, and a clear gradient pore structure is prepared.

[0123] Example 5

[0124] A carbon fiber pre-oxidized filament felt preform A with a surface density of 20g / m 2 , a bulk density of 0.10g / cm 3 and a carbon fiber pre-oxidized filament felt preform B with a surface density of 20g / m 2 , a bulk density of 0.2g / cm 3The carbon fiber pre-oxidized filament felt preform B is dipped in the epoxy resin solution with the epoxy resin content of 15wt% for impregnation treatment. The carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after the impregnation treatment are taken out and are respectively subjected to rolling treatment. The mass of the carbon fiber pre-oxidized filament felt preform A and the mass of the carbon fiber pre-oxidized filament felt preform B after the impregnation treatment and the rolling treatment are respectively 8.65 times and 8.67 times of the mass of the carbon fiber pre-oxidized filament felt preform A and the mass of the carbon fiber pre-oxidized filament felt preform B without the impregnation treatment and the rolling treatment. The carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B after the rolling treatment are laminated. The laminated carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B are subjected to hot-pressing and curing treatment at 170℃ and 3MPa for 10min to obtain the laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B with the thickness of 120μm. The laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B is subjected to carbonization treatment at 900℃ for 10min in an inert atmosphere. Then, the laminated body of the carbon fiber pre-oxidized filament felt preform A and the carbon fiber pre-oxidized filament felt preform B is subjected to graphitization treatment at 1600℃ for 10min. The carbon fiber felt with the areal density of 40g / m 2 , the average volume resistivity of 13.66mΩ·cm, a large number of pore structures distributed at the pore diameters of 15μm, 30μm, 40μm, 60μm, 90μm and 150μm, and the obvious gradient pore structure is prepared.

[0125] Example 6

[0126] The carbon fiber felt prepared in Example 1 is dipped in the PTFE solution for 5min, dried, and then sintered at 350℃ for 1h to obtain the hydrophobic carbon fiber felt with the PTFE content of 20%. A microporous layer material composed of water as solvent, acetylene black and carbon nanotubes with the mass ratio of 9:1, and carbon (acetylene black + carbon nanotubes) and PTFE with the mass ratio of 7:3 is coated on the B face of the hydrophobic carbon fiber felt by using a doctor blade, and then sintered at 350℃ for 1h to obtain the gas diffusion layer with the carbon loading of the microporous layer of 2.35mg / cm 2 The gas diffusion layer is subjected to laser drilling to control the pore diameter of 10μm, the pore spacing of 1mm, and the pores distributed throughout the gas diffusion layer.

[0127] Comparative Example 6

[0128] The difference from Example 6 is that the gas diffusion layer with the carbon loading of the microporous layer of 2.31mg / cm 2 The gas diffusion layer is not subjected to laser drilling treatment.

[0129] Comparative Example 6a

[0130] The difference from Example 6 is that the carbon fiber felt prepared in Comparative Example 1 was used, resulting in a carbon fiber felt with a base layer of non-gradient pores and a carbon loading of 2.31 mg / cm³ in the microporous layer. 2 The gas diffusion layer.

[0131] The gas diffusion layers prepared in Examples 6, 6, and 6a were respectively assembled into single cells using commercial catalyst / proton exchange membrane (CCM) modules. During assembly, the microporous layer side was positioned close to the CCM. The single cell was tested at a temperature of 75°C, a back pressure of 1.5 atm, and a relative humidity of 100% for both the anode and cathode gases. The Pt loading in the catalyst layer was 0.4 mg / cm³. 2 The effective area is 25cm² 2 The obtained single-cell polarization curve (100% humidity) is as follows: Figure 6 As shown. By Figure 6 It can be seen that the gas diffusion layer assembled single cell in Example 6 exhibits better battery performance and superior gas-liquid transport properties. It also demonstrates better drainage performance at high current densities, with a maximum power density of approximately 1.46 W / cm³. 2 However, both Comparative Example 6 and Comparative Example 6a's gas diffusion layer assembled single cells experienced water flooding under high current density, resulting in a rapid decline in battery performance. The maximum power density of Comparative Example 6 and Example 6 was approximately 0.91 W / cm². 2 1.05W / cm 2 The battery polarization curve shows poor performance.

[0132] Example 7

[0133] The carbon fiber felt prepared in Example 1 was immersed in FEP solution for 5 min, dried, and then sintered at 300℃ for 1 h to obtain a hydrophobic carbon fiber felt with an FEP content of 18%. A microporous layer material composed of ethanol as solvent, conductive carbon black VXC-72(R) and graphene oxide in a mass ratio of 7:3, and carbon (conductive carbon black VXC-72(R) + graphene oxide) and FEP in a mass ratio of 7:3 was coated onto the B side of the hydrophobic carbon fiber felt using a scraper. This material was then sintered at 350℃ for 1 h to obtain a gradient-pore carbon fiber felt as the base layer and a carbon loading of 2.20 mg / cm³ in the microporous layer. 2 The gas diffusion layer was laser-drilled, with a hole diameter of 100 μm, a hole spacing of 5 mm, and holes distributed throughout the gas diffusion layer.

[0134] Comparative Example 7

[0135] The difference from Example 7 is that the resulting substrate layer is a gradient-pore carbon fiber felt, and the carbon loading of the microporous layer is 2.23 mg / cm³. 2 The gas diffusion layer was not laser-drilled.

[0136] The gas diffusion layers prepared in Example 7 and Comparative Example 7 were respectively assembled into single cells with a commercial catalyst / proton exchange membrane (CCM) module. During assembly, the microporous layer side was close to the CCM. The single cell was tested at a temperature of 75°C, a back pressure of 1.5 atm, a relative humidity of 100% for both the anode and cathode gases, and a Pt loading of 0.4 mg / cm³ for the catalyst layer. 2 The effective area is 25cm² 2 The obtained single-cell polarization curve (100% humidity) is as follows: Figure 7 As shown. By Figure 7 It is evident that the gas diffusion layer assembled single cell in Example 7 exhibits superior battery performance, and its porous structure further facilitates gas-liquid transport. It also demonstrates better drainage performance at high current densities, achieving a maximum power density of approximately 1.40 W / cm². 2 The maximum power density of Comparative Example 7 is only about 0.98 W / cm³. 2 .

[0137] Comparative Example 7a

[0138] The difference from Example 7 is that the carbon fiber paper prepared in Example 1c was used as the substrate layer. The resulting substrate layer was a gradient-pore carbon fiber paper, and the carbon loading of the microporous layer was 2.23 mg / cm³. 2 The gas diffusion layer. The maximum power density of the assembled single cell was measured to be approximately 1.08 W / cm². 2 .

[0139] Example 8

[0140] The carbon fiber felt prepared in Example 1 was immersed in FEP solution for 5 minutes, dried, and then sintered at 300°C for 2 hours to obtain a hydrophobic carbon fiber felt with an FEP content of 18%. A microporous layer material composed of ethylene glycol as solvent, a 1:4 mass ratio of Ketjen black to carbon nanotubes, and a 7:3 mass ratio of carbon (Ketjen black + carbon nanotubes) to FEP was coated onto the B-side of the hydrophobic carbon fiber felt using a scraper. This material was then sintered at 350°C for 1 hour to obtain a gradient-pore carbon fiber felt as the base layer and a carbon loading of 2.30 mg / cm³ in the microporous layer. 2 The gas diffusion layer was laser-drilled, with a hole diameter of 50 μm, a hole spacing of 2 mm, and holes distributed throughout the gas diffusion layer.

[0141] Comparative Example 8

[0142] The difference from Example 8 is that the substrate layer is a gradient-pore carbon fiber felt, and the carbon loading of the microporous layer is 2.32 mg / cm³. 2 The gas diffusion layer was not laser-drilled.

[0143] The gas diffusion layers prepared in Example 8 and Comparative Example 8 were respectively assembled into single cells with a commercial catalyst / proton exchange membrane (CCM) module. During assembly, the microporous layer side was close to the CCM. The single cell was tested at a temperature of 75°C, a back pressure of 1.5 atm, a relative humidity of 100% for both the anode and cathode gases, and a Pt loading of 0.4 mg / cm³ for the catalyst layer. 2 The effective area is 25cm² 2 The obtained single-cell polarization curve (100% humidity) is as follows: Figure 8 As shown. By Figure 8 It is evident that the gas diffusion layer assembled single cell in Example 8 exhibits superior battery performance, and its porous structure further facilitates gas-liquid transport. It also demonstrates better drainage performance at high current densities, achieving a maximum power density of approximately 1.53 W / cm². 2 In contrast, the maximum power density of Comparative Example 8 is only about 0.84 W / cm³. 2 .

[0144] Example 9

[0145] The carbon fiber felt prepared in Example 1 was immersed in a PTFE solution for 5 minutes, dried, and then sintered at 350°C for 2 hours to obtain a hydrophobic carbon fiber felt with a PTFE content of 23%. A microporous layer material composed of isopropanol as a solvent, a 1:1 mass ratio of conductive carbon black BP2000 to graphene oxide, and a 7:3 mass ratio of carbon (conductive carbon black BP2000 + graphene oxide) to PVDF was coated onto the B-side of the hydrophobic carbon fiber felt using a scraper. This material was then sintered at 350°C for 1 hour to obtain a gradient-pore carbon fiber felt as the base layer and a carbon loading of 2.42 mg / cm³ in the microporous layer. 2 The gas diffusion layer was laser-drilled, with a hole diameter of 25 μm, a hole spacing of 1 mm, and holes distributed throughout the gas diffusion layer.

[0146] The gas diffusion layer prepared in Example 9 was used to assemble a single cell with a commercial catalyst / proton exchange membrane (CCM) module. During assembly, the microporous layer side was placed close to the CCM. The single cell was tested at a temperature of 75°C, a back pressure of 1.5 atm, a relative humidity of 100% for both the anode and cathode gases, and a Pt loading of 0.4 mg / cm³ for the catalyst layer. 2 The effective area is 25cm² 2 The maximum power density of a single cell was measured to be 1.62 W / cm³. 2 .

[0147] Comparative Example 9

[0148] Unlike Example 9, the laser-drilled holes had a diameter of 150 μm and a spacing of 6 mm. Experiments revealed that under high current density, flooding occurred, with the maximum power density being only approximately 0.93 W / cm². 2 .

[0149] Table 4 is a comparison table of gas diffusion layers and single cell performance of Examples 6-9, Comparative Examples 6-9, and Comparative Examples 6a-7a.

[0150] Table 4 is a comparison table of gas diffusion layers and single cell performance of Examples 6-9, Comparative Examples 6-9, and Comparative Examples 6a-7a.

[0151]

[0152] In combination with Table 4, by comparing Example 6 with Comparative Example 6a, it can be seen that, compared with the single cell using the carbon fiber felt with no gradient pore structure as the base layer, the single cell using the carbon fiber felt with gradient pore structure as the base layer can obtain a maximum power density of 1.46 W / cm 2 By comparing Example 6 with Comparative Example 6, Example 7 with Comparative Example 7, Example 8 with Comparative Example 8, and Example 9 with Comparative Example 9, it can be seen that, by performing laser drilling on the primary gas diffusion layer, and controlling the pore diameter and the pore spacing within a preset range (pore diameter of 10 μm-100 μm, and pore spacing of 1 mm-5 mm), the single cell with better water vapor management capability can be obtained. By comparing Example 7 with Comparative Example 7a, it can be seen that, compared with the single cell using the carbon fiber paper with gradient pore structure, the single cell using the carbon fiber felt with gradient pore structure has better water vapor management capability, that is, has better water vapor management capability.

[0153] The maximum power density of the single cell assembled by the embodiments of the present specification can be 1.4 W / cm 2 -1.7 W / cm 2 In some embodiments, the maximum power density of the single cell can be 1.45 W / cm 2 -1.7 W / cm 2 In some embodiments, the maximum power density of the single cell can be 1.5 W / cm 2 -1.7 W / cm 2 In some embodiments, the maximum power density of the single cell can be 1.55 W / cm 2 -1.7 W / cm 2 In some embodiments, the maximum power density of the single cell can be 1.6 W / cm 2 -1.7 W / cm 2 In some embodiments, the maximum power density of the single cell can reach 1.40 W / cm 2 , 1.46 W / cm 2 , 1.50 W / cm 2 , 1.53 W / cm 2 , 1.60 W / cm 2 , 1.62 W / cm 21.65 W / cm 2 1.7 W / cm 2 .

[0154] It should be noted that the thickness of the at least two carbon fiber pre-oxidized filament felt preforms after hot pressing and curing is measured by TECLOCK SM-114 thickness gauge. The volume resistivity in the embodiments of the present specification refers to the volume resistivity in the plane direction, which is measured according to the carbon material resistivity determination method specified in GB / T24525-2009 GB. The pore size distribution in the embodiments of the present specification is measured according to GB / T 21650.1-2008 solid material pore size distribution determination method. The above table only lists the parameters with obvious differences and greater influence on the experimental results.

[0155] The beneficial effects that may be brought by the embodiments of the present specification include but are not limited to: (1) by stacking and processing at least two carbon fiber pre-oxidized filament felt preforms with different bulk densities, a carbon fiber felt with a gradient pore structure can be prepared; (2) the carbon fiber felt with a gradient pore structure provided in the embodiments of the present specification has a simple preparation process and does not have carbon fiber miscibility phenomenon, and is easy to implement in industry; (3) by controlling the mass of the carbon fiber pre-oxidized filament felt preform after impregnation treatment and rolling treatment to be 6-9 times the mass of the carbon fiber pre-oxidized filament felt preform without impregnation treatment and rolling treatment, the phenomenon of uneven distribution or aggregation of thermosetting resin at the contact interface between the at least two carbon fiber pre-oxidized filament felt preforms after stacking can be avoided, and further the prepared carbon fiber felt can have better performance; (4) the single cell assembled by the gas diffusion layer with a gradient pore structure and regular pores prepared in the embodiments of the present specification has better cell performance, and the gradient pore structure of the carbon fiber felt of the base layer and the regular pores obtained by laser treatment are both beneficial to gas-liquid transmission, and have excellent gas-liquid transmission performance, and have better drainage performance under a larger current density (for example, 1000 mA / cm 2 -2400 mA / cm 2 ).

[0156] It should be noted that different embodiments may have different beneficial effects, and in different embodiments, the beneficial effects that may be produced can be any one or a combination of several of the above, or any other beneficial effect that can be obtained.

[0157] Having described the basic concepts, it is obvious that the above detailed disclosure is merely intended for purposes of illustration and is not intended to limit the present specification. Although the present specification has not explicitly described, those skilled in the art can make various modifications, improvements and corrections to the present specification. Such modifications, improvements and corrections are suggested in the present specification, and thus still belong to the spirit and scope of the exemplary embodiments of the present specification.

[0158] Meanwhile, the present specification uses specific terms to describe the embodiments of the present specification. As "one embodiment", "an embodiment", and / or "some embodiments" mean that a certain feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present specification. Therefore, it is emphasized and noted that "a" or "one" embodiment or "an" or "one" alternative embodiment appearing in various positions of the present specification does not necessarily refer to the same embodiment. In addition, certain features, structures, or characteristics of one or more embodiments of the present specification can be properly combined.

[0159] Further, unless the claim explicitly states otherwise, the order of the processing elements and sequences, the use of the lettering, or the use of other designations in the present specification are not intended to limit the order of the processes and methods of the present specification. Although some presently preferred inventive embodiments are discussed in the above disclosure by various examples, it is to be understood that such details are merely for the purpose of illustration, and additional claims are not limited to the disclosed embodiments, but rather intended to cover all modifications and equivalent arrangements included within the spirit and scope of the inventive embodiments. For example, although the system components described above can be implemented by hardware devices, they can also be implemented by software solutions only, such as installing the described system on an existing server or mobile device.

[0160] Similarly, it is to be noted that, in order to simplify the description of the present specification and to help the understanding of one or more inventive embodiments, the above description of the embodiments of the present specification sometimes combines various features into one embodiment, drawing, or description of the same. However, this disclosure method does not mean that the features required by the present specification are more than those mentioned in the claims. In fact, the features of the embodiments are less than all the features of the above-disclosed single embodiment.

[0161] In some embodiments, numbers describing the quantity of components and attributes are used. It should be understood that such numbers used in the description of embodiments are modified in some examples with the terms "approximately," "approximately," or "generally." Unless otherwise stated, "approximately," "approximately," or "generally" indicates that the numbers are allowed to vary by ±20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may be changed depending on the characteristics required by individual embodiments. In some embodiments, numerical parameters should take into account specified significant digits and employ a general method of digit reservation. Although the numerical ranges and parameters used to confirm their breadth of range in some embodiments of this specification are approximate values, in specific embodiments, such values ​​are set as precisely as feasible.

[0162] For each patent, patent application, patent application publication, and other material, such as articles, books, specifications, publications, and documents, referenced in this specification, the entire contents of which are incorporated herein by reference. This excludes historical application documents that are inconsistent with or conflict with the content of this specification, as well as documents that limit the broadest scope of the claims in this specification (currently or subsequently appended to this specification). It should be noted that in the event of any inconsistency or conflict between the descriptions, definitions, and / or terminology used in the supplementary materials to this specification and the content of this specification, the descriptions, definitions, and / or terminology used in this specification shall prevail.

[0163] Finally, it should be understood that the embodiments described in this specification are merely illustrative of the principles of the embodiments described herein. Other variations may also fall within the scope of this specification. Therefore, alternative configurations of the embodiments described herein are intended to be illustrative rather than limiting, and should be considered consistent with the teachings of this specification. Accordingly, the embodiments described herein are not limited to those explicitly introduced and described herein.

Claims

1. A method for preparing carbon fiber felt, characterized in that, The method includes: preparing carbon fiber felt using a carbon fiber pre-oxidized felt preform with a three-dimensional structure that does not require secondary carbonization treatment, including: Each of at least two types of carbon fiber pre-oxidized felt preforms undergoes impregnation and rolling treatments, wherein... The carbon fiber pre-oxidized filament preform refers to polyacrylonitrile carbon fiber pre-oxidized short fiber felt, which is obtained by needle punching or hydroentangling. The bulk densities of the at least two types of carbon fiber pre-oxidized felt preforms are not equal; The process of stacking the at least two types of carbon fiber pre-oxidized felt preforms after the rolling treatment includes: stacking the at least two types of carbon fiber pre-oxidized felt preforms after the rolling treatment in order of increasing or decreasing bulk density; and The at least two types of carbon fiber pre-oxidized felt preforms, after being stacked, are subjected to hot-press curing, carbonization, and graphitization to obtain the carbon fiber felt; wherein, The difference in bulk density between the two adjacent carbon fiber pre-oxidized felt preforms in the stacked structure is 0.1 g / m³. 3 -0.4 g / m 3 ; The mass of the carbon fiber pre-oxidized felt preform after the impregnation and rolling treatments is 6-9 times the mass of the carbon fiber pre-oxidized felt preform without the impregnation and rolling treatments. The thickness of the at least two carbon fiber pre-oxidized felt preforms after hot-press curing is 80μm-400μm.

2. The method for preparing carbon fiber felt according to claim 1, characterized in that, The bulk density of the at least two types of carbon fiber pre-oxidized felt preforms is 0.1 g / m³. 3 -0.5g / m 3 .

3. A carbon fiber felt, characterized in that, It is prepared using the method for preparing carbon fiber felt as described in any one of claims 1-2.

4. A method for preparing a battery diffusion layer, characterized in that, The method includes: Hydrophobic treatment is performed on the carbon fiber felt described in claim 3 to obtain hydrophobic carbon fiber felt; A microporous layer material is coated onto the side of the hydrophobic carbon fiber felt with a higher bulk density, and then processed to obtain a preliminary gas diffusion layer; and The initial gas diffusion layer is laser-drilled to obtain the battery diffusion layer; wherein, The diameter of the laser-drilled hole is 10μm-100μm; The spacing between the laser-drilled holes is 1mm-5mm.

5. A battery, characterized in that, The battery includes a battery diffusion layer prepared by the method for preparing the battery diffusion layer as described in claim 4.

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