Porous carbon felt structure

Abstract

The invention relates to a porous carbon felt structure which comprises a carbon felt plate, a plurality of porous channels are formed in the carbon felt plate, and the axes of the porous channels are perpendicular to the flow direction of electrolyte on the carbon felt plate and parallel to the thickness direction of the carbon felt plate; a long-strip-shaped flow channel parallel to the flow direction of electrolyte is arranged on a traditional carbon felt plate, the proportion of a low-flow-speed area is 78.01%, according to the pore channel carbon felt structure, the pore channels perpendicular to the flow direction of the electrolyte are arranged on the carbon felt plate to serve as the flow channels, the proportion of the low-flow-speed area is reduced to 6.12%, the pressure loss of the electrolyte flowing on the carbon felt plate is effectively reduced, and the service life of the carbon felt plate is prolonged. The flow velocity of the electrolyte on the carbon felt plate is improved, and the uniformity of flow velocity distribution is also remarkably improved.

Description

Technical Field

[0001] The invention relates to the field of liquid flow battery structures, and in particular to a pore carbon felt structure. Background Art

[0002] Liquid flow battery is a low-cost, high-efficiency, environmentally friendly liquid flow energy storage battery with the advantages of high energy density and current efficiency, simple and easy operation of the device, long service life and low cost. All-vanadium redox flow battery (all-vanadium flow battery) has good application prospects in new energy power generation and energy storage and power grid peak and valley cutting. The stack is the place where the all-vanadium liquid flow battery carries out electrochemical reactions. It determines the power characteristics of the system. The performance of the stack will directly affect the overall performance of the system. An all-vanadium liquid flow battery stack is essentially composed of multiple single cells stacked and connected in series. They are generally stacked and tightened by a press. There is one or more electrolyte circulation systems inside, and the current input and output ports are a unified set. The main components of the all-vanadium liquid flow single cell include: electrodes, bipolar plates, diaphragms, end plates, seals and other fasteners.

[0003] The factors that affect the performance of flow batteries are complex and diverse, including the performance parameters of the battery component materials (ion exchange membrane, bipolar plate, carbon felt, electrolyte, etc.), and the influence of fluid mass transfer inside the battery is also crucial. The mass transfer inside the battery includes the flow of electrolyte in the carbon felt flow channel, the penetration of electrolyte in the carbon felt electrode, and the process of species in the electrolyte penetrating across the membrane. The uneven distribution of electrolyte in the carbon felt flow channel leads to large concentration polarization of the battery, which limits the improvement of battery performance.

[0004] The fibers in the carbon felt are not evenly arranged, and its surface is not smooth. The pressure difference between the electrolyte inlet and outlet of unmodified carbon felt is large, and the large resistance to electrolyte flow leads to large concentration polarization at various locations on the electrode surface, affecting the overall performance of the battery. At present, the design of the flow channel of carbon felt is focused on the form of long strips of flow channels. Since the long strip cavities are dug out on the carbon felt electrode as the flow channel, the flow velocity in the flow channel area and the carbon felt area is very different, which leads to too low flow velocity in the electrode areas on both sides of the middle of the flow channel, resulting in insufficient reactants during transportation. Therefore, one of the key technologies to improve battery performance is to reasonably design the microchannels on the carbon felt, reduce the resistance of the electrolyte to flow on the porous electrode, and improve the continuity of the supply of active substances. Summary of the invention

[0005] The purpose of the present invention is to provide a porous carbon felt structure in order to overcome the defects of the above-mentioned prior art, reduce the flow resistance of the electrolyte, and improve the problem of uneven electrolyte flow rate caused by the carbon felt flow channel.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A pore carbon felt structure comprises a carbon felt plate, on which a plurality of pores are arranged, wherein the axes of the pores are perpendicular to the flow direction of electrolyte on the carbon felt plate and parallel to the thickness direction of the carbon felt plate.

[0008] In one embodiment, the heights of the plurality of holes are different.

[0009] In one embodiment, the carbon felt sheet includes a first layer close to the flow battery graphite plate, a third layer close to the flow battery ion exchange membrane, and a second layer located between the first layer and the third layer, a portion of the pores penetrates the first layer, another portion of the pores penetrates the first layer and the second layer, and another portion of the pores penetrates the first layer, the second layer and the third layer.

[0010] In one of the embodiments, the width direction of the carbon felt plate is perpendicular to the flow direction of the electrolyte, the length direction of the carbon felt plate is parallel to the flow direction of the electrolyte, and the plurality of channels are distributed in sequence in the width direction of the carbon felt plate to form a plurality of channel row groups, and the channel heights of the channel row groups increase in sequence along the flow direction of the electrolyte.

[0011] In one of the embodiments, the width direction of the carbon felt plate is perpendicular to the flow direction of the electrolyte, the length direction of the carbon felt plate is parallel to the flow direction of the electrolyte, a plurality of the channels are evenly distributed in the width direction of the carbon felt plate to form a plurality of channel row groups, and the distance between two adjacent channel row groups in the length direction of the carbon felt plate is the same.

[0012] In one embodiment, the channels in two adjacent channel row groups are staggered in the width direction;

[0013] Alternatively, the channels in the plurality of channel row groups are aligned in the width direction.

[0014] In one embodiment, the number of channels included in the channel row group increases successively along the flow direction of the electrolyte.

[0015] In one embodiment, the hole comprises a cylindrical hole, and the radius of the hole is 1 mm to 20 mm.

[0016] In one of the embodiments, the width direction of the carbon felt plate is perpendicular to the flow direction of the electrolyte, the length direction of the carbon felt plate is parallel to the flow direction of the electrolyte, and the plurality of channels are distributed in sequence in the width direction of the carbon felt plate to form a plurality of channel row groups, and the apertures of the plurality of channel row groups decrease in sequence along the flow direction of the electrolyte.

[0017] In one embodiment, the sum of the end surface areas of the plurality of pores satisfies the following relationship: 0.05S2≤S1≤0.55S2, S1 is the sum of the end surface areas of the plurality of pores, and S2 is the board area of ​​the carbon felt board.

[0018] Compared with the prior art, the present invention has the following advantages:

[0019] 1. A long strip flow channel parallel to the flow direction of the electrolyte is set on the traditional carbon felt plate, and the low flow rate area accounts for 78.01%. The above-mentioned pore carbon felt structure, by setting a pore perpendicular to the flow direction of the electrolyte on the carbon felt plate as a flow channel, reduces the proportion of the low flow rate area to 6.12%, effectively reduces the pressure loss of the electrolyte flowing on the carbon felt plate, increases the flow rate of the electrolyte on the carbon felt plate, and significantly improves the uniformity of the flow rate distribution.

[0020] 2. The above-mentioned pore carbon felt structure is provided with pores of different heights, and the electrolyte flow rate at different thickness positions of the carbon felt plate can be controlled by controlling the height of the pores. The carbon felt plate is further divided into a first layer, a second layer and a third layer. The pore height can penetrate one, two or three layers respectively, so that the first layer, the second layer and the third layer of the carbon felt plate have different flow rates, thereby improving the uniformity of the electrolyte flow rate distribution.

[0021] 3. In the process of electrolyte flowing from the electrolyte inlet to the electrolyte outlet on the carbon felt plate, the closer the carbon felt plate is to the electrolyte outlet, the greater the flow resistance and the lower the flow rate. Therefore, the closer the position on the carbon felt plate is to the electrolyte outlet, the greater the height of the channel is, the more the number of channels in each row is, and the smaller the aperture of the channel is, so as to reduce the flow resistance near the electrolyte outlet on the carbon felt plate, ensure that the flow rates near the outlet and near the inlet on the carbon felt plate are close, and improve the continuity of electrolyte supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the porous carbon felt structure in the first embodiment of the present invention.

[0023] Figure 2 Schematic diagram of the porous carbon felt structure in the second embodiment of the present invention.

[0024] Figure 3 Schematic diagram of the porous carbon felt structure in the third embodiment of the present invention.

[0025] Figure 4 Schematic diagram of the porous carbon felt structure in the fourth embodiment of the present invention.

[0026] Figure 5 It is a cross-sectional view of a porous carbon felt structure in one embodiment of the present invention.

[0027] Figure 6It is a schematic diagram of the carbon felt structure in the prior art.

[0028] Figure numerals: 100, pore carbon felt structure; 10, carbon felt plate; 11, first layer; 12, second layer; 13, third layer; 20, pore; 30, pore row group; 40, long strip flow channel. DETAILED DESCRIPTION

[0029] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0030] The pore carbon felt structure 100 in some embodiments is described in detail below with reference to the accompanying drawings.

[0031] like Figures 1 to 5 As shown, in one embodiment, a porous carbon felt structure 100 is provided, including a carbon felt plate 10, on which a plurality of pores 20 are provided, wherein the axis of the pores 20 is perpendicular to the flow direction of the electrolyte on the carbon felt plate 10 and parallel to the thickness direction of the carbon felt plate 10.

[0032] The traditional carbon felt plate 10 is provided with a long strip flow channel 40 parallel to the flow direction of the electrolyte, and the low flow velocity area accounts for 78.01%. The above-mentioned pore carbon felt structure 100, by providing a pore 20 perpendicular to the flow direction of the electrolyte as a flow channel on the carbon felt plate 10, reduces the proportion of the low flow velocity area to 6.12%, effectively reduces the pressure loss of the electrolyte flowing on the carbon felt plate 10, increases the flow velocity of the electrolyte on the carbon felt plate 10, and significantly improves the uniformity of the flow velocity distribution.

[0033] Specifically, Figure 5 As shown, in one embodiment, the heights of the plurality of channels 20 are different.

[0034] Furthermore, if Figure 5 As shown, in one embodiment, the carbon felt sheet 10 includes a first layer 11 close to the graphite plate of the flow battery, a third layer 13 close to the ion exchange membrane of the flow battery, and a second layer 12 located between the first layer 11 and the third layer 13, a portion of the pores 20 penetrates the first layer 11, another portion of the pores 20 penetrates the first layer 11 and the second layer 12, and another portion of the pores 20 penetrates the first layer 11, the second layer 12 and the third layer 13.

[0035] The above-mentioned pore carbon felt structure 100 is provided with pores 20 of different heights. The electrolyte flow rate at different thickness positions of the carbon felt board 10 can be controlled by controlling the height of the pores 20. The carbon felt board 10 is further divided into a first layer 11, a second layer 12 and a third layer 13. The height of the pores 20 can penetrate one, two or three layers respectively, so that the first layer 11, the second layer 12 and the third layer 13 of the carbon felt board 10 have different flow rates, thereby improving the uniformity of the electrolyte flow rate distribution.

[0036] Furthermore, if Figure 5 As shown, in one embodiment, the width direction of the carbon felt plate 10 is perpendicular to the flow direction of the electrolyte, and the length direction of the carbon felt plate 10 is parallel to the flow direction of the electrolyte. A plurality of channels 20 are distributed in sequence in the width direction of the carbon felt plate 10 to form a plurality of channel row groups 30, and the height of the channels 20 of the channel row groups 30 increases in sequence along the flow direction of the electrolyte.

[0037] Specifically, Figure 1 and Figure 2 As shown, in one embodiment, the width direction of the carbon felt plate 10 is perpendicular to the flow direction of the electrolyte, and the length direction of the carbon felt plate 10 is parallel to the flow direction of the electrolyte. A plurality of channels 20 are evenly distributed in the width direction of the carbon felt plate 10 to form a plurality of channel row groups 30, and the distance between two adjacent channel row groups 30 in the length direction of the carbon felt plate 10 is the same.

[0038] Furthermore, if Figure 2 As shown, in one embodiment, the channels 20 in two adjacent channel rows 30 are staggered in the width direction. That is, the first channels 20 in two adjacent channel rows 30 are non-aligned in the length direction, so more columns of channels 20 along the length direction can be formed on the carbon felt sheet 10, the distribution density of the channels 20 in the width direction is increased, and the flow rate uniformity of the electrolyte at different width positions is further increased.

[0039] Alternatively, if Figure 1 As shown, in one embodiment, the channels 20 in a plurality of channel rows 30 are aligned in the width direction.

[0040] Specifically, Figure 3 As shown, in one embodiment, the number of channels 20 included in the channel row group 30 increases successively along the flow direction of the electrolyte.

[0041] Specifically, Figures 1 to 5 As shown, in one embodiment, the channel 20 comprises a cylindrical channel, and the radius of the channel 20 is 1 mm to 20 mm.

[0042] Optionally, the channel 20 includes a polygonal prism-shaped channel 20, including a triangular prism channel, a regular quadrangular prism channel, and a regular hexagonal prism channel.

[0043] Furthermore, if Figure 4 As shown, in one embodiment, the width direction of the carbon felt plate 10 is perpendicular to the flow direction of the electrolyte, the length direction of the carbon felt plate 10 is parallel to the flow direction of the electrolyte, and a plurality of channels 20 are distributed in sequence in the width direction of the carbon felt plate 10 to form a plurality of channel row groups 30, and the apertures of the plurality of channel row groups 30 decrease in sequence along the flow direction of the electrolyte.

[0044] In the process of electrolyte flowing from the electrolyte inlet to the electrolyte outlet on the carbon felt plate 10, the closer the carbon felt plate 10 is to the electrolyte outlet, the greater the flow resistance and the lower the flow rate. Therefore, the closer the position on the carbon felt plate 10 is to the electrolyte outlet, the greater the height of the channel 20 is set, the greater the number of channels 20 in each row, and the smaller the aperture of the channel 20, so as to reduce the flow resistance near the electrolyte outlet on the carbon felt plate 10, ensure that the flow rates near the outlet and near the inlet on the carbon felt plate 10 are close, and improve the continuity of the electrolyte supply.

[0045] Specifically, in one embodiment, the sum of the end surface areas of the plurality of channels 20 satisfies the following relationship: 0.05S2≤S1≤0.55S2, S1 is the sum of the end surface areas of the plurality of channels 20, and S2 is the board area of ​​the carbon felt board 10.

[0046] The beneficial effects of the porous carbon felt structure 100 are described below in conjunction with some embodiments.

[0047] Example 1

[0048] No flow channel is provided on the carbon felt plate 10, the pressure loss is 70.3 kPa, and the low flow velocity area accounts for 1.03%.

[0049] Example 2

[0050] The carbon felt plate 10 is provided with Figure 6 The cross-finger flow channel shown, that is, the long strip flow channel 40 arranged alternately in long and short directions, has a pressure loss of 33.2 kPa, and the low flow velocity area accounts for 78.01%.

[0051] Example 3

[0052] The carbon felt plate 10 is provided with a plurality of pores 20, and the plurality of pores 20 are evenly distributed on the carbon felt plate 10 (eg Figure 1 As shown), the sum of the end surface areas of the channel 20 satisfies: S1=0.2S2, the radius of the channel 20 is 6 mm, the pressure loss is 59.7 kPa, and the low flow rate area accounts for 11.21%.

[0053] Example 4

[0054] The carbon felt plate 10 is provided with a plurality of channels 20, and the plurality of channels 20 are arranged in a staggered manner on the carbon felt plate 10 (eg Figure 2As shown), the sum of the end surface areas of the channel 20 satisfies: S1=0.2S2, the radius of the channel 20 is 6 mm, the pressure loss is 64.4 kPa, and the low flow rate area accounts for 6.12%.

[0055] Example 5

[0056] The carbon felt plate 10 is provided with a plurality of pores 20, and the number of pores 20 in each row decreases in sequence along the flow direction of the electrolyte on the carbon felt plate 10 (e.g. Figure 3 As shown), the sum of the end surface areas of the channel 20 satisfies: S1=0.2S2, the radius of the channel 20 is 6 mm, the pressure loss is 62.4 kPa, and the low flow rate area accounts for 10.58%.

[0057] Example 6

[0058] The carbon felt plate 10 is provided with a plurality of pores 20. The number of pores 20 in each row increases gradually along the flow direction of the electrolyte on the carbon felt plate 10, and the radius of the pores 20 in each row decreases gradually (e.g. Figure 4 As shown), the sum of the end surface areas of the channels 20 satisfies: S1=0.2S2, the radius of the first row of channels 20 is 18 mm, the radius of the second row of channels 20 is 14 mm, the radius of the third row of channels 20 is 10 mm, the radius of the fourth row of channels 20 is 6 mm, the radius of the fifth row of channels 20 is 2 mm, the pressure loss is 50.3 kPa, and the low flow rate area accounts for 15.37%.

[0059] According to Examples 1 to 6, after the channels 20 are provided on the carbon felt plate 10, the pressure loss is reduced compared with that of Example 1 without the channels, and the proportion of the low flow velocity area is reduced compared with that of Example 2 with the interdigital channels. According to the effects of Example 3 and Example 1, the pressure loss of the carbon felt plate 10 provided with the channels 20 is reduced from 70.3 kPa to 59.7 kPa, and the pressure loss is reduced by about 8.49%. According to the effects of Examples 3 and 2, the proportion of the low flow velocity area of ​​the carbon felt plate 10 provided with the channels 20 is significantly reduced compared with the traditional interdigital channels, from 78.01% to 11.21%, indicating that after the channels 20 are provided, the uniformity of the flow velocity distribution inside the carbon felt plate 10 is significantly improved.

[0060] Compared with Example 3, the staggered arrangement of the channels in Example 4 can further reduce the proportion of the low velocity area, improve the uniformity of the velocity distribution, and ensure that the electrolyte fully reacts in the carbon felt plate 10. In addition, the arrangement of increasing the number of channels and decreasing the channel radius in Example 6 effectively reduces the pressure loss compared with Example 3, but the low velocity area remains at a similar level.

[0061] Table 1 Pressure loss and low flow rate area ratio of different embodiments.

[0062]

[0063]

[0064] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0066] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0067] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0068] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0069] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A porous carbon felt structure, characterized in that: It comprises a carbon felt plate (10), wherein a plurality of pores (20) are provided on the carbon felt plate (10), wherein the axes of the pores (20) are perpendicular to the flow direction of electrolyte on the carbon felt plate (10) and parallel to the thickness direction of the carbon felt plate (10).

2. A porous carbon felt structure according to claim 1, characterized in that: The heights of the plurality of holes (20) are different.

3. A porous carbon felt structure according to claim 2, characterized in that: The carbon felt sheet (10) comprises a first layer (11) close to a graphite sheet of a liquid flow battery, a third layer (13) close to an ion exchange membrane of the liquid flow battery, and a second layer (12) located between the first layer (11) and the third layer (13); a portion of the pores (20) penetrates the first layer (11), another portion of the pores (20) penetrates the first layer (11) and the second layer (12), and another portion of the pores (20) penetrates the first layer (11), the second layer (12), and the third layer (13).

4. A porous carbon felt structure according to claim 2, characterized in that: The width direction of the carbon felt plate (10) is perpendicular to the flow direction of the electrolyte, and the length direction of the carbon felt plate (10) is parallel to the flow direction of the electrolyte. The plurality of pores (20) are distributed in sequence in the width direction of the carbon felt plate (10) to form a plurality of pore row groups (30), and the heights of the pores (20) of the pore row groups (30) increase in sequence along the flow direction of the electrolyte.

5. The porous carbon felt structure according to claim 1, characterized in that: The width direction of the carbon felt plate (10) is perpendicular to the flow direction of the electrolyte, and the length direction of the carbon felt plate (10) is parallel to the flow direction of the electrolyte. The plurality of pores (20) are evenly distributed in the width direction of the carbon felt plate (10) to form a plurality of pore row groups (30), and the distance between two adjacent pore row groups (30) in the length direction of the carbon felt plate (10) is the same.

6. A porous carbon felt structure according to claim 5, characterized in that: The holes (20) in two adjacent hole row groups (30) are arranged in a staggered manner in the width direction; Alternatively, the channels (20) within the plurality of channel row groups (30) are arranged aligned in the width direction.

7. The porous carbon felt structure according to claim 5, characterized in that: The number of channels (20) included in the channel row group (30) increases successively along the flow direction of the electrolyte.

8. The porous carbon felt structure according to claim 1, characterized in that: The hole (20) comprises a cylindrical hole, and the radius of the hole (20) is 1 mm to 20 mm.

9. The porous carbon felt structure according to claim 8, characterized in that: The width direction of the carbon felt plate (10) is perpendicular to the flow direction of the electrolyte, and the length direction of the carbon felt plate (10) is parallel to the flow direction of the electrolyte. The plurality of pores (20) are distributed in sequence in the width direction of the carbon felt plate (10) to form a plurality of pore row groups (30), and the apertures of the plurality of pore row groups (30) decrease in sequence along the flow direction of the electrolyte.

10. The porous carbon felt structure according to claim 1, characterized in that: The sum of the end surface areas of the plurality of pores (20) satisfies the following relationship: 0.05S2≤S1≤0.55S2, S1 is the sum of the end surface areas of the plurality of pores (20), and S2 is the plate surface area of ​​the carbon felt plate (10).

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