Cascade heat exchangers and gas separators for metal-air batteries

Abstract

A metal-air battery equipped with a heat exchanger. The heat exchanger has air-side fins directly connected to a backplate and liquid-side fins thermally connected to the backplate. The liquid-side fins receive liquid electrolyte from an overflow port and allow the liquid electrolyte to flow over the fins into a liquid electrolyte compartment. The liquid-side fins are arranged alternately, adjacent fins separated by gaps and at an angle (θ) to each other, so that the liquid electrolyte flows down in a cascade manner over adjacent fins. The heat exchanger simultaneously degasss the electrolyte and removes excess heat.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application is a non - provisional application claiming the priority of U.S. Patent Application No. 63 / 501,090, filed on May 9, 2023, and is hereby incorporated herein by reference in its entirety.

Background Art

[0002] Metal - air batteries provide a high - energy - density power source and are expected to have promising applications as mobile power sources and stationary distributed power sources. They have the potential to replace internal combustion engines found in hybrid vehicles, locomotives, ships, and aircraft because their energy density and conversion efficiency are approaching those of hydrocarbon fuels.

[0003] Metal - air batteries have faced many problems that have so far hindered their use in the aforementioned fields. The distance between the oxygen reduction reaction (ORR) material and the current - collecting screen causes electrical resistance losses during operation. Since the metal anode is consumed during battery discharge, the distance between the cathode and the anode increases over time. This change in electrode spacing increases the IR (electrical resistance) loss and decreases the output power over time. Furthermore, when the battery is operated in an open - circuit or no - load condition, hydrogen gas is rapidly generated in the electrolyte, which further increases the IR loss and prevents the battery from returning to full output when re - connected to a closed circuit. 2 R (electrical resistance) loss and decreases the output power over time. Furthermore, when the battery is operated in an open - circuit or no - load condition, hydrogen gas is rapidly generated in the electrolyte, which further increases the IR loss and prevents the battery from returning to full output when re - connected to a closed circuit. 2 R loss and prevents the battery from returning to full output when re - connected to a closed circuit.

[0004] Many attempts have been made to solve the aforementioned problems. Much research has been conducted on the chemical properties of electrolyte additives that can suppress hydrogen gas generation, but without major success. Limited successes include the testing of several detachable electrode designs that incorporate features to protect against corrosion and gas generation at the anode ends. Other designs have attempted to mount the anode in a movable device to reduce resistance increases by varying the distance between the anode and cathode. These are mechanically complex and have been shown to limit the ability to quickly load fresh metal anodes into metal-air batteries. None of these solutions have been successfully applied in combination, resulting in metal-air batteries being disposable and unsuitable for intermittent power applications. [Overview of the project]

[0005] This disclosure provides a metal-air battery equipped with a heat exchanger. The heat exchanger has air-side fins directly connected to a backplate and liquid-side fins thermally connected to the backplate. The liquid-side fins receive liquid electrolyte from an overflow port and allow the liquid electrolyte to flow over the liquid-side fins into a liquid electrolyte compartment. The liquid-side fins are arranged alternately with adjacent fins at an angle (θ) to each other and separated by gaps so that the liquid electrolyte flows down in a cascading manner over adjacent fins. The heat exchanger simultaneously degasss the electrolyte and removes excess heat.

[0006] This disclosure provides a metal-air battery. The metal-air battery comprises a chamber having a liquid electrolyte compartment and an anode, a cathode, an overflow port, and a liquid electrolyte input section for introducing liquid electrolyte from the liquid electrolyte compartment into the chamber, the liquid electrolyte input section being located at the lower end of the chamber and the overflow port being located at the upper end of the chamber. The heat exchanger comprises a plurality of air-side fins directly connected to a backplate and a plurality of liquid-side fins thermally connected to the backplate. The plurality of liquid-side fins are arranged in an overflow path that receives liquid electrolyte from the overflow port and allows the liquid electrolyte to pass over the plurality of liquid-side fins and flow into the liquid electrolyte compartment. The plurality of liquid-side fins consist of adjacent first fins and second fins that are alternately arranged at an angle (θ) greater than 0° and less than 135° to each other, and are separated by a gap so that the liquid electrolyte flows in a cascade manner from the distal end of the first fin through the gap to the proximal end of the second fin.

[0007] The description of the present invention provided herein is intended solely to provide a brief overview of the subject matter disclosed herein in accordance with one or more exemplary embodiments and is not intended to serve as a guide for interpreting the claims or to define or limit the scope of the invention, which is defined solely by the appended claims. This brief description is provided to introduce in a simplified form an exemplary selection of concepts further described in the detailed description. This brief description is not intended to identify any major or essential features of the subject matter of the claims, nor is it intended to be used as an aid in determining the scope of the subject matter of the claims. The subject matter of the claims is not limited to embodiments that resolve any or all of the disadvantages pointed out in the background art.

[0008] To provide a clearer understanding of the features of the present invention, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, these drawings are illustrative of some embodiments of the present invention and do not limit the scope of the invention. The scope of the present invention also includes other embodiments that achieve equivalent effects. Furthermore, the drawings are not necessarily drawn to scale and are focused on clearly illustrating the features of specific embodiments. In each figure, the same or corresponding parts are denoted by the same reference numerals. Therefore, for a detailed understanding of the present invention, please refer to the following detailed description in conjunction with the drawings. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a perspective view of a heat exchanger. [Figure 2] Figure 2 shows a metal-air battery using the heat exchanger described above. [Figure 3] Figure 3 shows the flow path of the liquid electrolyte inside a metal-air battery. [Figure 4] Figure 4 shows the flow path of hydrogen gas within a metal-air battery. [Figure 5] Figure 5A is a plan view of the air-side fins of the heat exchanger. Figure 5B is a plan view of the liquid-side fins 112. Figure 5C is a side view showing the air-side fins and liquid-side fins connected by fasteners. [Figure 6] Figure 6 is a detailed view of the liquid-side fins. [Figure 7] Figure 7 shows another embodiment in which the liquid-side fins are in direct contact with the first and second side walls of the heat exchanger. Detailed description of the invention

[0010] Figure 1 shows a heat exchanger 100. The heat exchanger 100 comprises a number of air-side fins 102 directly connected to a back plate 104. Each air-side fin extends outward from the back plate 104 in a direction 106 with a depth 108 over a length 110 of the back plate 104.

[0011] The heat exchanger 100 further comprises a plurality of liquid-side fins 112 that are thermally connected to the back plate 104. In the embodiment of Figure 1, the liquid-side fins 112 are directly connected to a mounting plate 114, which in turn is directly connected to the back plate 104. Both the plurality of air-side fins 102 and the plurality of liquid-side fins 112 are formed of a thermally conductive material, thereby placing these components in thermal contact with one another. Each liquid-side fin extends outward from the back plate 104 in direction 116 with a depth of 118. Each liquid-side fin also has a width of 120. In the embodiment of Figure 1, directions 106 and 116 are opposite.

[0012] Figure 2 shows one embodiment in which the heat exchanger 100 is used. The metal-air battery 200 is shown in a two-part cross-sectional view. The anode 202 and cathode 204 are located in a chamber 206 filled with electrolyte. As shown in more detail in Figure 3, the liquid electrolyte flows from the electrolyte-filled chamber 206 over the liquid-side fins 112 into the electrolyte compartment 208, and is then reused.

[0013] Figure 3 shows the flow path of the liquid electrolyte through the metal-air battery 200. The liquid electrolyte is introduced into the chamber 206 at the liquid electrolyte input section 300 using an electrolyte fluid pump 302 to draw liquid electrolyte from the electrolyte compartment 208. The chamber 206 is filled with liquid electrolyte until it reaches the overflow port 304. The liquid electrolyte input section 300 is located at the lower end of the chamber 206, while the overflow port 304 is located at the upper end of the chamber, which allows the chamber to be filled with liquid electrolyte and immerse the anode 202 and cathode 204. The overflowing liquid electrolyte is carried by gravity through the overflow path 306, which is positioned to receive the liquid electrolyte and pass over the liquid-side fins 112. The liquid-side fins 112 conduct heat from the liquid electrolyte and transfer it to the air-side fins 112, thereby cooling the liquid electrolyte before it is returned to the electrolyte chamber 208 for reuse. Because the electrolyte chamber 208 is located below the overflow path 306, cooling of the liquid electrolyte is gravity-driven, minimizing the use of pumps. As described in detail elsewhere in this specification, the hydrogen gas produced by the electrolysis reaction is knocked out (separated) from the liquid electrolyte by the configuration of the liquid-side fins 112.

[0014] Figure 4 shows the flow path of hydrogen gas within the metal-air battery 200. The hydrogen gas separated from the liquid electrolyte by the liquid-side fins 112 rises in the direction of arrow 400 and comes into contact with the mist eliminator 402. The lower surface of the mist eliminator 402 is sloped so that the condensed liquid returns to the overflow path 306. The gas, such as hydrogen gas, continues to flow until it is discharged from the gas outlet 404. The hydrogen gas itself plays a role in transferring heat from the metal-air cell 200, and an increase in the knockout amount contributes to an improved cooling effect. The released hydrogen can be burned together with the ambient air using an external combustion device. In one embodiment, the combustion device is positioned directly above the air-side fins 102, and the rising airflow (thermal siphon) generated by the combustion draws the air upward through the air-side fins 102, further increasing the cooling efficiency.

[0015] Figure 5A is a plan view of the air-side fins 102. The air-side fins 102 are arranged parallel to each other along their longitudinal direction 110, forming elongated parallel airflow paths. In this embodiment, these airflow paths are arranged vertically, and heat is carried upward by natural convection and dissipated from the metal-air battery system 200. In one embodiment, the cooling effect can be further enhanced by forcibly flowing air over the air-side fins 102. The air-side fins 102 have at least one hole 500 in the rear plate 104, which is used to attach the liquid-side fins 112 later. In one embodiment, the air-side fins 102 and the rear plate 104 are formed as a single unit.

[0016] Figure 5B is a plan view of the liquid-side fin 112. The liquid-side fin 112 also has at least one hole 502 in the mounting plate 114, which is used to later attach the air-side fin 102. In one embodiment, the liquid-side fin 112 and the mounting plate 114 are an integral structure.

[0017] Figure 5C is a side view showing the air-side fin 102 and the liquid-side fin 112 connected by fasteners 504 (e.g., bolts or screws). In one embodiment, the air-side fin 102, the rear plate 104, and the liquid-side fin 112 are formed as a single unit. In another embodiment, the liquid-side fin 112 can be directly connected to the rear plate 104 by welding or the like, without using the mounting plate 114. Furthermore, to prevent the liquid electrolyte from leaking out of the overflow path 306, a sealant (e.g., a silicone-based sealant) may be applied to the joint 506 between the rear plate 104 and the mounting plate 114.

[0018] In one embodiment, the heat exchanger 100 is made of a metal (e.g., brass, copper, etc.) that is stable in the alkaline environment of a typical electrolyte and has thermal conductivity. In one embodiment, the surface of the liquid-side fin 112 may be nickel-plated to provide further corrosion resistance. In embodiments in which the air-side fin 102 and the liquid-side fin 112 are manufactured separately, different materials can be used. With such a configuration, it is possible to form the air-side fin 102 from a first material (e.g., aluminum) and the liquid-side fin 112 from a second material (e.g., copper or brass). This makes it possible to use aluminum for the ambient air while preventing the aluminum (a common anode material) from coming into contact with the liquid electrolyte.

[0019] FIG. 6 is a detailed view of the liquid-side fins 112. The liquid-side fins 112 are composed of a plurality of first fins 601 close to the first side wall 600 and a plurality of second fins 602 close to the second side wall 603. The first side wall 600 and the second side wall 603 form an overflow path 306 (see FIG. 3). The first fins 601 and the second fins 602 are alternately arranged on the overflow path 306 and form an angle (θ) with each other. The angle θ is defined as an angle formed inward with respect to the width direction 120 (see FIG. 1) of each adjacent fin. In one embodiment, the angle (θ) is greater than 0° and less than 135°. In another embodiment, the angle (θ) is at least 45° and less than 120°. In yet another embodiment, the angle (θ) is 80° or more and 100° or less, and in other embodiments, the angle (θ) is 90°.

[0020] As shown in FIG. 6, the first fin 601 is divided into a proximal portion 601a and a distal portion 601b, and the second fin 602 is similarly divided into a proximal portion 602a and a distal portion 602b. The distal end of each fin (e.g., the distal end 601b) terminates above the proximal end of the adjacent lower fin (e.g., the proximal end 602a). With such a configuration, the liquid electrolyte flows down sequentially in a cascade along the inclined surface of the fin, passes through the gap 604, and returns to the electrolyte compartment 208 (see FIG. 3). Without being limited to a specific theory, it is considered that the liquid electrolyte thins by contacting the high surface area portion of the liquid-side fins 112. This thinning is presumed to be a factor in the high hydrogen gas knockout efficiency.

[0021] FIG. 7 is a diagram showing another embodiment, in which the first fin 601 directly contacts the first side wall 600 and the second fin 602 directly contacts the second side wall 603.

[0022] While the present invention has been described in relation to specific embodiments, it will be understood by those skilled in the art that various modifications can be made and their elements substituted with equivalents to adapt them to specific circumstances without departing from the scope of this disclosure. Therefore, the claims are not limited to the specific embodiments disclosed, but are intended to encompass all embodiments included within the scope and spirit of the appended claims.

Claims

1. It is a metal-air battery, A metal-air cell comprising a chamber having a liquid electrolyte compartment, an anode, a cathode, an overflow port, and a liquid electrolyte input section for introducing liquid electrolyte from the liquid electrolyte compartment into the chamber, wherein the liquid electrolyte input section is located at the lower end of the chamber and the overflow port is located at the upper end of the chamber; and a heat exchanger comprising a plurality of air-side fins directly connected to a back plate, The backplate is thermally connected to a plurality of liquid-side fins, the plurality of liquid-side fins being arranged in an overflow path that receives liquid electrolyte from the overflow port and allows the liquid electrolyte to pass over the plurality of liquid-side fins and flow into the liquid electrolyte compartment, The aforementioned plurality of liquid-side fins consist of adjacent first fins and second fins arranged alternately at an angle (θ) greater than 0° and less than 135° to each other, and are separated by a gap so that the liquid electrolyte flows in a cascade manner from the distal end of the first fin through the gap to the proximal end of the second fin, in a heat exchanger and A metal-air battery equipped with the following features.

2. The metal-air battery according to claim 1, wherein the angle (θ) is between 45° and 120°.

3. The metal-air battery according to claim 1, wherein the angle (θ) is between 80° and 100°.

4. The metal-air battery according to claim 1, wherein the angle (θ) is 90°.

5. The metal-air battery according to claim 1, wherein each of the air-side fins in the plurality of air-side fins is parallel to one another along its length in order to provide a long, narrow, parallel airflow path arranged in the vertical direction.

6. The metal-air battery according to claim 1, characterized in that each liquid-side fin extends outward from the rear plate in a first direction and has the depth of a first fin, and each air-side fin extends in a second direction and has the depth of a second fin, the second direction being opposite to the first direction.

7. The metal-air battery according to claim 1, characterized in that multiple air-side fins and a rear plate are integrated into a single structure.

8. The metal-air battery according to claim 1, characterized in that a plurality of liquid-side fins are directly attached to a mounting plate, and the mounting plate is directly attached to a rear plate.

9. The metal-air battery according to claim 8, characterized in that multiple liquid-side fins and mounting plates are integrated into a single structure.

10. The metal-air battery according to claim 1, characterized in that multiple liquid-side fins are directly attached to the rear plate.

11. The metal-air battery according to claim 1, characterized in that multiple air-side fins, multiple liquid-side fins, and a rear plate are integrated into a single structure.

12. The metal-air battery according to claim 1, characterized in that the air-side fin and the liquid-side fin are formed from different metals.

13. The metal-air battery according to claim 1, characterized in that the air-side fins are made of aluminum and the liquid-side fins do not contain aluminum.

14. The metal-air battery according to claim 1, wherein the distal end of the first fin terminates directly above the proximal end of the second fin.

Images