Energy storage coupling system based on hydrogen fuel cell and flow cell

Abstract

The utility model discloses an energy storage coupling system based on a hydrogen fuel cell and a flow cell, which relates to the technical field of flow cell energy storage, and comprises a flow cell, evaporation and concentration units and a hydrogen fuel cell, the evaporation concentration unit comprises a preheating device and an electric evaporation concentrator, and a liquid outlet of the preheating device is communicated with a liquid inlet of the electric evaporation concentrator; the hydrogen fuel cell is communicated with the gas-liquid separator, the gas-liquid separator is communicated with the water storage tank, and the water storage tank is respectively communicated with the positive electrode liquid storage tank and the negative electrode liquid storage tank through the water pump. A large amount of energy which cannot be connected to a grid is consumed by utilizing the evaporation and concentration unit, so that the electrolyte of the flow battery is evaporated and concentrated, the concentration of the electrolyte is improved, the energy density of the flow battery is increased, water generated in the power generation process of the hydrogen fuel battery participates in water replenishing of the positive electrode liquid storage tank and the negative electrode liquid storage tank, circulating supply of water is realized, and the power generation efficiency is improved. The discharge capacity is increased.

Description

Technical Field

[0001] This utility model relates to the technical field of flow battery energy storage, specifically to an energy storage coupling system with adjustable electrolyte concentration in a flow battery. Background Technology

[0002] A flow battery is a novel electrochemical energy storage device, primarily composed of a positive electrolyte, a negative electrolyte, electrodes, and a separator. During charging, the active materials in the electrolyte undergo redox reactions on the electrode surfaces, storing electrical energy at the positive and negative electrodes, respectively. During discharging, this stored chemical energy is converted back into electrical energy through the reverse redox reaction. For example, the vanadium redox battery is a typical flow battery. During charging, vanadium ions undergo redox reactions in the electrolyte; in the positive electrolyte, they are oxidized to vanadium, while in the negative electrolyte, they are reduced to vanadium. During discharging, the reaction proceeds in reverse, with electrons flowing from the negative electrode to the positive electrode through an external circuit, generating current.

[0003] Applications of flow batteries include: 1. Renewable energy storage: In renewable energy fields such as solar and wind power generation, the intermittent and unstable nature of power generation necessitates effective energy storage systems to balance power supply. Flow batteries can store this unstable electrical energy and release it when needed, thereby improving the utilization rate of renewable energy. 2. Grid peak shaving: Flow batteries can store electrical energy during periods of low grid load and release it during periods of high grid load, thus playing a role in peak shaving and valley filling. This helps stabilize the voltage and frequency of the grid, improving the grid's operating efficiency and reliability. For example, at night when grid load is low, inexpensive electricity can be used to charge the flow batteries, and the stored electrical energy can be transmitted to the grid during peak daytime hours.

[0004] Flow batteries have a low energy density, approximately 20 kWh / m³. 3 This is mainly due to the low concentration of the electrolyte. Generally, the higher the electrolyte concentration, the greater the energy density of the flow battery. This is because in a flow battery, the active material in the electrolyte is the key component for storing and releasing energy. Taking a vanadium redox flow battery as an example, vanadium ions in the electrolyte are the active material that participates in redox reactions. When the concentration of vanadium ions in the electrolyte increases, more active material can participate in the reaction per unit volume of electrolyte, thus storing and releasing more energy during charging and discharging. For example, within a certain range, if the vanadium ion concentration is increased from 1 mol / L to 2 mol / L, the energy density of the battery may increase accordingly because more vanadium ions can undergo redox reactions on the electrode surface to store and release electrical energy.

[0005] However, increasing electrolyte concentration does not guarantee an unlimited increase in energy density. On one hand, excessively high electrolyte concentrations can lead to increased electrolyte viscosity. Increased viscosity affects the fluidity of the electrolyte within the battery system, hindering its circulation between the positive and negative electrodes. For example, when the electrolyte concentration is too high, its fluidity deteriorates, slowing the diffusion of active materials to the electrode surface and thus reducing the battery's reaction rate and performance. On the other hand, excessively high concentrations can also cause problems such as salting out. When the concentration of a solute (such as vanadium ions) exceeds its solubility limit in the solvent, solid substances will precipitate out, which can damage the battery system and affect its performance and lifespan.

[0006] When designing and applying flow batteries, the impact of electrolyte concentration on energy density and other performance characteristics must be comprehensively considered. Electrolyte concentration is typically optimized based on the specific battery type, operating conditions, and application scenario. For example, in energy storage applications with high energy density requirements but relatively low requirements for battery response speed, such as large-scale energy storage power stations, the electrolyte concentration can be appropriately increased. However, measures must be taken to prevent issues such as increased viscosity and salting out, such as optimizing the electrolyte formulation or improving battery temperature control and cycling systems. Conversely, in applications with high requirements for response speed and cycle performance, a relatively lower electrolyte concentration may be chosen to ensure good electrolyte flowability and battery responsiveness.

[0007] Chinese invention patent No. 2020105573274 discloses a polymer flow battery system. The system includes a positive electrode active material and a negative electrode active material. The positive electrode active material is TEMPO-functionalized polymer nanoparticles, and the negative electrode active material is zirconia-functionalized polymer nanoparticles. Both the positive and negative electrode active materials are organic polymers. Polymers possess good stability and diverse design capabilities, effectively preventing cross-contamination between ions and addressing the efficiency reduction issue that arises from increasing discharge capacity by raising electrolyte concentration.

[0008] Chinese invention patent No. 2023104044493 discloses a vanadium redox flow battery, its electrolyte, and a method for improving the energy density of the electrolyte. Current all-vanadium redox flow batteries suffer from the problem of not being able to maintain high stability while achieving high energy density. The electrolyte of this invention includes a positive electrode electrolyte and a negative electrode electrolyte; the positive electrode electrolyte includes a positive vanadium ion pair and a positive auxiliary redox couple, wherein the positive vanadium ion pair is VO2. + / VO 2+ The positive electrode auxiliary redox couple is selected from I0 3- / I - Br2 / Br - Cr2O72- / Cr 3+ This invention adds an auxiliary redox couple to the electrolyte, increasing the battery's energy density without causing electrolyte corrosion, thus conforming to the green and environmentally friendly characteristics of vanadium batteries. All of the above patents solve the problem of maintaining high stability in the electrolyte of flow batteries while achieving high energy density.

[0009] Currently, how to rationally adjust the electrolyte concentration of flow batteries according to energy storage and power generation needs to improve energy density is a technical problem to be solved. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and to provide an energy storage coupling system based on a hydrogen fuel cell and a flow battery.

[0011] To achieve the above objectives, this utility model provides the following technical solution:

[0012] An energy storage coupling system based on a hydrogen fuel cell and a flow battery includes a flow battery, a positive electrode storage tank, and a negative electrode storage tank. The positive electrode storage tank is connected to the positive electrolyte outlet and positive electrolyte inlet of the flow battery via a positive electrode circulation pump. The negative electrode storage tank is connected to the negative electrolyte outlet and negative electrolyte inlet of the flow battery via a negative electrode circulation pump. The system further includes:

[0013] An evaporation and concentration unit is provided in the circulating water path between the positive electrode electrolyte outlet and the positive electrode storage tank of the flow battery, and between the negative electrode electrolyte outlet and the negative electrode storage tank of the flow battery. The evaporation and concentration unit includes a preheating device and an electric evaporator, and the outlet of the preheating device is connected to the inlet of the electric evaporator.

[0014] The hydrogen fuel cell has its outlet connected to the inlet of a gas-liquid separator, and its outlet connected to a water storage tank. The water storage tank is connected to the positive electrode storage tank and the negative electrode storage tank via a water pump.

[0015] By adopting the above technical solution, surplus or off-peak electricity that cannot be connected to the grid can be used to power the evaporation and concentration unit, providing flexibility in terms of timing. The evaporation and concentration unit increases the concentration of the electrolyte; the higher the electrolyte concentration, the greater the energy density of the flow battery. This significantly saves space in the positive and negative electrode storage tanks, reducing the overall weight of the flow battery system. Although the electrolyte concentration is high and the energy density is large, it cannot be completely released during discharge. By diluting the electrolyte concentration with water, the discharge capacity can be increased. Therefore, it can be coupled with a hydrogen fuel cell, utilizing the water generated during the hydrogen fuel cell's power generation process to replenish the positive and negative electrode storage tanks.

[0016] Preferably, it also includes a photovoltaic power generation component, which is electrically connected to the preheating device and the electric evaporator concentrator respectively.

[0017] By adopting the above technical solution, the electrolyte is concentrated through a preheating device and an electroevaporator, consuming a large amount of energy that cannot be connected to the grid.

[0018] Preferably, both the positive electrode storage tank and the negative electrode storage tank are equipped with electrolyte concentration sensors.

[0019] By adopting the above technical solution, the electrolyte concentration in the positive and negative electrode storage tanks is detected by the electrolyte concentration sensor. When the evaporation and concentration unit is working, if the electrolyte concentration reaches the preset concentration, the evaporation and concentration unit stops working.

[0020] Preferably, it also includes a hydrogen storage cylinder, which is connected to the hydrogen fuel cell via a pipeline.

[0021] By adopting the above technical solution, the hydrogen storage cylinder stores hydrogen gas for supplying hydrogen to the hydrogen fuel cell.

[0022] Compared with related technologies, the energy storage coupling system based on hydrogen fuel cells and flow batteries provided by this utility model has the following beneficial effects:

[0023] 1. This application utilizes an evaporation and concentration unit to evaporate and concentrate the electrolyte in a flow battery, increasing the electrolyte concentration. Power is supplied to the evaporation and concentration unit from surplus or off-peak electricity that cannot be connected to the grid. The evaporation and concentration unit offers flexible operating hours. The higher the electrolyte concentration, the greater the energy density of the flow battery. Evaporation quickly and cost-effectively eliminates peak power demand, maximizing system efficiency. This significantly saves space occupied by the positive and negative electrode storage tanks, reducing the overall weight of the flow battery system.

[0024] 2. This application utilizes the water generated during the hydrogen fuel cell power generation process to replenish the positive and negative electrode storage tanks, thereby achieving a water circulation supply. By diluting the electrolyte concentration with water, the discharge capacity can be increased. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of an energy storage coupling system based on a hydrogen fuel cell and a flow battery.

[0026] Reference numerals: 1. Flow battery; 2. Positive electrode reservoir; 3. Negative electrode reservoir; 4. Positive electrode circulation pump; 5. Negative electrode circulation pump; 6. Preheating device; 7. Electro-evaporator concentrator; 8. Hydrogen fuel cell; 9. Gas-liquid separator; 10. Water storage tank; 11. Photovoltaic power generation module; 12. Hydrogen storage cylinder. Detailed Implementation

[0027] The technical solutions in the embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art are within the protection scope of this utility model.

[0028] In the description of this utility model, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and do not require that this utility model be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model. The terms "connected" and "linked" used in this utility model should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; they can refer to a direct connection or an indirect connection through intermediate components. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0029] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. Example

[0030] like Figure 1 As shown, this embodiment provides an energy storage coupling system based on a hydrogen fuel cell and a flow battery, including a flow battery 1, a positive electrode storage tank 2, a negative electrode storage tank 3, an evaporation and concentration unit, and a hydrogen fuel cell 8. The positive electrode storage tank 2 is connected to the positive electrode electrolyte outlet and the positive electrode electrolyte inlet of the flow battery 1 through a positive electrode circulation pump 4, forming the positive electrode circulation water path of the flow battery 1. The negative electrode storage tank 3 is connected to the negative electrode electrolyte outlet and the negative electrode electrolyte inlet of the flow battery 1 through a negative electrode circulation pump 5, forming the negative electrode circulation water path of the flow battery 1.

[0031] An evaporation and concentration unit is installed in the circulating water path between the positive electrolyte outlet and the positive electrolyte storage tank 2 of the flow battery 1, and between the negative electrode electrolyte outlet and the negative electrode storage tank 3 of the flow battery 1. These units are used to adjust the electrolyte concentration in the positive electrode storage tank 2 and the negative electrode storage tank 3, respectively. Specifically, the evaporation and concentration unit includes a preheating device 6 and an electroevaporator 7. The inlet of the preheating device 6 is connected to either the positive electrolyte outlet or the negative electrode electrolyte outlet, and the outlet of the preheating device 6 is connected to the inlet of the electroevaporator 7. The outlet of the electroevaporator 7 is connected to either the positive electrode storage tank 2 or the negative electrode storage tank 3. The preheating device 6 preheats the electrolyte, which then enters the electroevaporation tank of the electroevaporator 7. The electrolyte is heated by graphite electrodes, thereby concentrating the solution. Both the preheating device 6 and the electroevaporator 7 used in this application are prior art.

[0032] A hydrogen fuel cell 8 is a device that directly converts chemical energy into electrical energy, generating electricity through the chemical reaction of H2 and O2. At the anode of the hydrogen fuel cell 8, H2 undergoes an oxidation reaction, decomposing into H+ under the action of a catalyst. + and e - The reaction is H2→2H + +2e - These hydrogen ions move towards the cathode through the electrolyte membrane, while electrons flow from the anode to the cathode through an external circuit, generating an electric current to power external devices. At the cathode, O2 undergoes a reduction reaction, where it reacts with H+ ions from the anode under the action of a catalyst. + and e - The reaction is O2 + 4H+. + +4e - →2H₂O. The overall chemical reaction equation is 2H₂ + O₂ → 2H₂O. This equation clearly shows that hydrogen and oxygen react to ultimately produce water. The outlet of the hydrogen fuel cell 8 is connected to the inlet of the gas-liquid separator 9, which separates the gas and water. The outlet of the gas-liquid separator 9 is connected to the water storage tank 10, storing the water within it. The water storage tank 10 is connected to the positive electrode storage tank 2 and the negative electrode storage tank 3 via a water pump, used to replenish water to both tanks.

[0033] The above are merely preferred embodiments of the present invention and do not limit the implementation methods and protection scope of the present invention. The present invention also has the following embodiments based on the above:

[0034] In this embodiment, a photovoltaic power generation module 11 is also included, which is electrically connected to the preheating device 6 and the electroevaporator 7. The preheating device 6 and the electroevaporator 7 concentrate the electrolyte, consuming a large amount of energy that cannot be connected to the grid.

[0035] In this embodiment, both the positive electrode storage tank 2 and the negative electrode storage tank 3 are equipped with electrolyte concentration sensors (not shown in the figure). The electrolyte concentration in the positive electrode storage tank 2 and the negative electrode storage tank 3 is detected by the electrolyte concentration sensors. When the evaporation and concentration unit is working, if the electrolyte concentration reaches the preset concentration, the evaporation and concentration unit stops working.

[0036] In this embodiment, a hydrogen storage cylinder 12 is also included. The hydrogen storage cylinder 12 is connected to the hydrogen fuel cell 8 through a pipeline. The hydrogen storage cylinder 12 stores hydrogen and is used to supply hydrogen to the hydrogen fuel cell 8.

[0037] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0038] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model shall be within the scope of protection of the pending claims of the present utility model.

Claims

1. An energy storage coupling system based on a hydrogen fuel cell and a flow battery, comprising a flow battery (1), a positive electrode storage tank (2), and a negative electrode storage tank (3), wherein the positive electrode storage tank (2) is connected to the positive electrode electrolyte outlet and the positive electrode electrolyte inlet of the flow battery (1) via a positive electrode circulation pump (4), and the negative electrode storage tank (3) is connected to the negative electrode electrolyte outlet and the negative electrode electrolyte inlet of the flow battery (1) via a negative electrode circulation pump (5), characterized in that, Also includes: An evaporation and concentration unit is provided in the circulating water path between the positive electrode electrolyte outlet and the positive electrode storage tank (2) of the flow battery (1) and between the negative electrode electrolyte outlet and the negative electrode storage tank (3) of the flow battery (1). The evaporation and concentration unit includes a preheating device (6) and an electric evaporator (7). The outlet of the preheating device (6) is connected to the inlet of the electric evaporator (7). The hydrogen fuel cell (8) has its outlet connected to the inlet of the gas-liquid separator (9), and its outlet connected to the water storage tank (10). The water storage tank (10) is connected to the positive electrode storage tank (2) and the negative electrode storage tank (3) respectively via a water pump.

2. The energy storage coupling system based on hydrogen fuel cell and flow battery according to claim 1, characterized in that: It also includes a photovoltaic power generation module (11), which is connected to the preheating device (6) and the electric evaporator (7) by circuit connection.

3. The energy storage coupling system based on hydrogen fuel cell and flow battery according to claim 1, characterized in that: Both the positive electrode storage tank (2) and the negative electrode storage tank (3) are equipped with electrolyte concentration sensors.

4. The energy storage coupling system based on hydrogen fuel cell and flow battery according to claim 1, characterized in that: It also includes a hydrogen storage cylinder (12), which is connected to the hydrogen fuel cell (8) via a pipeline.

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