A flow battery structure

Abstract

The present invention provides a structure for a liquid flow battery. The battery is composed of a positive electrode side battery end plate, a positive current collecting plate, a positive shunt electrode frame, a positive electrode, a positive bus electrode frame, an ion membrane, a negative bus electrode frame, a negative electrode, a negative shunt electrode frame, a negative current collecting plate, a negative battery end plate, and sealing materials between the various components. This battery structure is different from the electrolyte circulation method in conventional liquid flow batteries. It adopts the smallest thickness direction in the electrode geometric dimensions as the electrolyte circulation direction. Its flow resistance is reduced by about two orders of magnitude compared to the method of flowing through the entire length or width of the electrode, and the flow resistance is also reduced compared to the interdigital flow channel or serpentine flow channel method of the fuel cell. The method of rapid distribution and rapid circulation of the electrolyte improves the distribution uniformity of the electrolyte concentration in the electrode, can significantly reduce concentration polarization, and improve the voltage efficiency of the battery.

Description

Technical Field

[0001] The present invention relates to a liquid flow battery structure, and in particular to a flow mode and structure of the liquid flow battery. Background Art

[0002] As humanity enters the new century, rapid social development is driving an increasing demand for energy. Overexploitation of traditional fossil fuels and the resulting massive carbon dioxide emissions are leading to frequent environmental problems. Achieving these goals is possible only through the large-scale utilization of renewable energy and a reduction in the proportion of traditional fossil fuels in the energy mix. As is well known, renewable energy is intermittent and unstable, necessitating an intermediate device to mitigate its adverse impact on the power grid. Energy storage technology has emerged to counteract this volatility by storing and releasing energy in a timely manner, thereby improving power quality. Chemical energy storage has seen rapid growth in recent years, primarily using traditional lead-acid and lithium-ion batteries, with hundreds of megawatts of energy storage power stations already built. However, safety remains a major concern for these energy storage systems, particularly with the frequent fires and explosions that have caused significant damage to personnel and property. Flow battery electrolytes contain no flammable organic components, are inherently safe, and can be used for deep charge and discharge cycles, with a lifespan of up to 15 years. Consequently, flow batteries are experiencing rapid growth, and their characteristics are particularly well-suited for scenarios requiring long-term energy storage.

[0003] A liquid flow battery system mainly consists of batteries, electrolyte storage tanks, electrolytes, and piping systems. Among them, batteries are the most critical components in a liquid flow battery system, determining the performance and reliability of the system and being the key location for chemical reactions. The key to improving the performance of a battery system is to improve the voltage efficiency of the battery. Voltage efficiency is improved by suppressing the battery's ohmic polarization, electrochemical polarization, and concentration polarization. For battery stacks with high operating current densities, controlling concentration polarization becomes the primary issue in polarization control. At the same time, the flow resistance within the battery should be as low as possible to reduce the resistance and the demand for excess energy for pump power. Therefore, developing a battery structure with low flow resistance, high electrolyte distribution uniformity, and low concentration polarization is crucial to improving the performance of the battery system. Summary of the Invention

[0004] In order to reduce the flow resistance inside the battery, improve the uniformity of electrolyte distribution, and reduce the concentration polarization of the battery stack, the present invention provides a structure of a liquid flow battery.

[0005] The battery comprises a positive electrode side battery end plate, a positive current collecting plate, a positive shunt electrode frame, a positive electrode, a positive bus electrode frame, an ion conducting membrane, a negative bus electrode frame, a negative electrode, a negative shunt electrode frame, a negative current collecting plate, and a negative battery end plate stacked in sequence;

[0006] The positive shunt electrode frame and the negative shunt electrode frame are respectively a flat plate, and a groove serving as an electrolyte flow channel is provided on the side of the flat plate close to the positive electrode and in the area in contact with the positive electrode.

[0007] A through hole serving as a positive electrolyte inlet and a through hole serving as a positive electrolyte outlet are provided on the positive shunt electrode frame. The positive electrolyte inlet is connected to the electrolyte flow channel on the positive shunt electrode frame, and the positive electrolyte inlet is connected to the positive electrolyte inlet on the positive side battery end plate.

[0008] A through hole serving as a negative electrolyte inlet and a through hole serving as a negative electrolyte outlet are provided on the negative shunt electrode frame. The negative electrolyte inlet is connected to the electrolyte flow channel on the negative shunt electrode frame, and the negative electrolyte inlet is connected to the negative electrolyte inlet on the negative side battery end plate.

[0009] The positive busbar frame and the negative busbar frame are each a flat plate, with a through-hole serving as an electrolyte flow channel provided in the contact area between the flat plate and the positive electrode. The positive busbar frame is provided with a through-hole serving as a positive electrolyte outflow outlet, which communicates with the through-hole in the electrolyte flow channel on the positive busbar frame. The positive electrolyte outflow outlet is connected to the positive electrolyte outlet on the positive shunt electrode frame and the positive electrolyte outlet on the positive-side battery end plate. The negative busbar frame is provided with a through-hole serving as a negative electrolyte outflow outlet, which communicates with the through-hole in the electrolyte flow channel on the negative busbar frame. The negative electrolyte outflow outlet is connected to the negative electrolyte outlet on the negative shunt electrode frame and the negative electrolyte outlet on the negative-side battery end plate.

[0010] In the above-described battery structure, the positive and negative electrolytes flow into the positive and negative shunt electrode frames, respectively, through the electrolyte inlets on the positive and negative battery end plates. The positive and negative electrolytes are distributed on the positive and negative electrode surfaces, respectively, and penetrate into the electrodes along the normal direction of the electrode surfaces. After passing through the thickness of the electrodes, they flow into the positive and negative bus electrode frames, respectively, and ultimately exit the battery through the electrolyte outlets on the positive and negative battery end plates, respectively.

[0011] In the above-described battery structure, the positive shunt electrode frame between the positive current collecting plate and the positive electrode, and the negative shunt electrode frame between the negative electrode and the negative current collecting plate, are conductive. The portions of the positive bus electrode frame and the negative bus electrode frame that contact the positive electrode and the negative electrode, respectively, may be conductive or non-conductive, preferably conductive.

[0012] In the above-mentioned battery structure, the parts of the positive bus electrode frame and the negative bus electrode frame that are in contact with the positive electrode and the negative electrode respectively can be non-porous materials or porous materials, preferably porous materials; the porosity of the porous material is 0.05-0.5 times the porosity of the electrode porous material, preferably 0.1-0.2 times.

[0013] In the above battery structure, the electrolyte flow channel can be one or more of a serpentine flow channel and an interdigitated flow channel. The porous material electrode can be one or more of carbon felt, carbon paper, and carbon cloth.

[0014] This battery structure differs from conventional flow battery electrolyte flow methods by using the smallest thickness of the electrode geometry as the electrolyte flow direction. This reduces flow resistance by approximately two orders of magnitude compared to methods that flow across the entire length or width of the electrode. Flow resistance is also lower than that of interdigitated or serpentine flow channels in fuel cells. This rapid electrolyte distribution and flow improves the uniformity of electrolyte concentration within the electrodes, significantly reducing concentration polarization and increasing the battery's voltage efficiency.

[0015] The present invention has the following advantages:

[0016] 1. The electrolyte flow method in the battery structure of the present invention adopts the smallest thickness direction of the electrode geometric dimensions as the electrolyte flow direction, and its flow resistance is reduced by about two orders of magnitude compared with the traditional liquid flow battery structure. This greatly reduces the pipe resistance and pump power of the battery system, and improves the energy efficiency of the entire system;

[0017] 2. The electrolyte circulation mode in the battery structure of the present invention and the rapid distribution and circulation of the electrolyte improve the distribution uniformity of the electrolyte concentration in the electrode, which can significantly reduce concentration polarization and improve the voltage efficiency of the battery. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The battery structure of a conventional liquid flow battery;

[0019] Among them: 1. Positive side battery end plate; 2. Positive current collector plate; 3. Positive electrode frame; 4. Positive electrode; 5. Ion conduction membrane; 6. Negative electrode; 7. Negative electrode frame; 8. Negative current collector plate; 9. Negative side battery end plate.

[0020] Figure 2 The battery structure of the liquid flow battery proposed by the present invention;

[0021] 10. Positive shunt electrode frame; 11. Positive bus electrode frame; 12. Negative bus electrode frame; 13. Negative shunt electrode frame

[0022] Figure 3 for Figure 2 The front (left) and back (right) structures of the 10th positive shunt electrode frame and the 13th negative shunt electrode frame in the medium flow battery structure;

[0023] 14. Positive electrode (in 10. Positive shunt electrode frame) or negative electrode (in 13. Negative shunt electrode frame) electrolyte inlet; 15. Recess serving as electrolyte flow channel; 16. Area on the positive shunt electrode frame for accommodating the positive electrode or area on the negative shunt electrode frame for accommodating the negative electrode; 17. Positive electrode electrolyte outlet (in 10. Positive shunt electrode frame) or negative electrode electrolyte outlet (in 13. Negative shunt electrode frame).

[0024] Figure 4 for Figure 2 The front (left) and back (right) structures of the 11. positive busbar frame and 12. negative busbar frame in the medium flow battery structure;

[0025] Among them, 18. The electrolyte outflow port of the positive electrode (in 11. The positive bus electrode frame) or the negative electrode (in 12. The negative bus electrode frame); 19. The through hole provided in the contact area between the bus electrode frame and the electrode as the electrolyte flow channel; 20. The area on the positive bus electrode frame for accommodating the positive electrode (in 11. The positive bus electrode frame) or the area on the negative bus electrode frame for accommodating the negative electrode (in 2. The negative bus electrode frame). DETAILED DESCRIPTION

[0026] Comparative Example:

[0027] A conventional liquid flow battery structure comprises a positive-side battery end plate 1, a positive current collector plate 2, a positive electrode frame 3, a positive electrode 4, an ion-conducting membrane 5, a negative electrode 6, a negative electrode frame 7, a negative current collector plate 8, a negative-side battery end plate 9, and seals between the components. The battery is compressed by bolts passing through corresponding through-holes in the positive-side battery end plate 1 and the negative-side battery end plate 9. The positive electrolyte flows into the battery through the electrolyte inlet on the positive-side battery end plate 1, flows through the electrolyte inlet through-holes in the positive current collector plate 2 into the electrolyte inlet of the positive electrode frame 3, flows through electrolyte distribution channels into the positive electrode 4, then flows out of the electrolyte outlet of the electrode frame through electrolyte converging channels, flows through the electrolyte outlet through-holes in the positive current collector plate 2, flows into the electrolyte outlet on the positive-side battery end plate 1, and exits the battery. The negative electrode electrolyte flows into the battery through the electrolyte inlet on the negative-side battery end plate 9, flows through the electrolyte inlet through-hole on the negative current collector plate 8 into the electrolyte inlet of the negative electrode frame 7, flows into the negative electrode 6 through the electrolyte distribution channel, then flows out of the electrolyte outlet of the electrode frame through the electrolyte converging channel, flows through the electrolyte outlet through-hole on the negative current collector plate 8 into the electrolyte outlet on the negative-side battery end plate 9, and flows out of the battery. The electrolyte distribution channel on the battery electrode frame adopts an interdigitated electrode structure. The electrolyte passes from the electrode near the channel surface through the electrode under the ribs of the interdigitated structure, flows into the adjacent channel, and then flows out from the surface near the channel.

[0028] Example

[0029] The present invention proposes a liquid flow battery structure, which consists of a positive side battery end plate 1; a positive current collecting plate 2; a positive shunt electrode frame 10; a positive electrode 4; a positive bus electrode frame 11; an ion conductive membrane 5; a negative bus electrode frame 12; a negative electrode 6; a negative shunt electrode frame 13; a negative current collecting plate 8; a negative side battery end plate 9 and seals between the various components, and the battery is compressed by bolts passing through corresponding through holes on the positive side battery end plate 1 and the negative side battery end plate 9.

[0030] The positive electrode electrolyte flows into the battery through the electrolyte inlet on the positive side battery end plate 1, passes through the electrolyte through-hole on the positive current collecting plate 2 and flows into the electrolyte inlet 14 of the positive shunt electrode frame 10, and flows into the 4 positive electrodes accommodated on 16 through the groove 15 of the electrolyte flow channel. The electrolyte penetrates into the electrode along the normal direction of the electrode surface, passes through the thickness direction of the electrode and flows into the through-hole 19 provided as the electrolyte flow channel in the contact area between the busbar electrode frame and the electrode, flows into the positive electrolyte outflow outlet 18 on the positive busbar electrode frame, and flows out of the battery through the electrolyte outlet 10 on the positive shunt electrode frame and the positive electrolyte outlet on the positive side battery end plate 1.

[0031] The negative electrode electrolyte flows into the battery through the electrolyte inlet on the negative side battery end plate 9, flows into the electrolyte inlet 14 of the negative shunt electrode frame 13 through the electrolyte through-hole on the negative current collecting plate 8, and flows into the negative electrode 6 accommodated on 16 through the groove 15 of the electrolyte flow channel. The electrolyte penetrates into the electrode along the normal direction of the electrode surface, passes through the thickness direction of the electrode and flows into the through-hole 19 provided as the electrolyte flow channel in the contact area between the busbar electrode frame and the electrode, flows into the negative electrolyte outflow outlet 18 on the negative busbar electrode frame, and flows out of the battery through the electrolyte outlet 13 on the negative shunt electrode frame and the negative electrolyte outlet on the negative side battery end plate 9.

[0032] The positive shunt electrode frame 10 and the negative shunt electrode frame 13 are identical in structure, differing only in assembly direction and function. The positive shunt electrode frame 10 and the negative shunt electrode frame 13 are respectively placed on both sides of the ion conductive membrane 5 and assembled relative to each other, and guide the positive and negative electrolytes respectively. Similarly, the positive bus electrode frame 11 and the negative bus electrode frame 12 are identical in structure, differing only in assembly direction and function. The positive bus electrode frame 11 and the negative bus electrode frame 12 are respectively placed on both sides of the ion conductive membrane 5 and assembled relative to each other, and guide the positive and negative electrolytes respectively.

[0033] The positive and negative electrolytes in the battery flow into the positive shunt electrode frame and the negative shunt electrode frame respectively through the electrolyte inlets of the positive and negative battery end plates; the positive and negative electrolytes are distributed on the electrode surfaces of the positive and negative electrodes respectively, and penetrate into the electrodes along the normal direction of the electrode surfaces, and after passing through the thickness direction of the electrodes, flow into the positive bus electrode frame and the negative bus electrode frame respectively, and finally flow out of the battery through the electrolyte discharge ports on the positive and negative battery end plates respectively.

[0034] The portions of the positive bus electrode frame 11 and the negative bus electrode frame 12 that are in contact with the positive electrode and the negative electrode respectively can be made of a non-porous material or a porous material.

[0035] Use Figure 1 and Figure 2 The battery structure in the figure is assembled into a battery and its performance is evaluated. Among them, electrodes 4 and 6 are porous carbon felt with a thickness of 3mm, the ion conductive membrane 5 adopts Nafion115 membrane, the positive current collecting plate 2 and the negative current collecting plate 8 are graphite plates, the positive electrode frame 3, the negative electrode frame 7, the positive shunt electrode frame 10 and the negative shunt electrode frame 13 are shunt electrode frames processed from hard graphite plates with a thickness of 3mm. The positive bus electrode frame 11 and the negative bus electrode frame 12 are bus electrode frames processed from hard graphite plates with a thickness of 1mm. Figure 1 and Figure 2 The battery performance of the battery structure assembled is shown in Table 1.

[0036] Table 1 uses Figure 1 and Figure 2 Battery performance of battery structure assembly

[0037]

[0038] As can be seen from Table 1, the Figure 2 The battery flow resistance of the structure is compared Figure 1 The battery structure is significantly reduced, which can effectively save pump energy consumption and improve the energy efficiency of the system. The uniform distribution of the electrolyte and the increase in flow rate brought about by the reduction of flow resistance effectively control the concentration polarization of the battery, and the voltage efficiency and energy efficiency are significantly improved by about 4 percentage points.

Claims

1. A flow battery structure, characterized in that: The battery comprises a positive electrode side battery end plate, a positive current collecting plate, a positive shunt electrode frame, a positive electrode made of a porous material, a positive bus electrode frame, an ion conducting membrane, a negative bus electrode frame, a negative electrode made of a porous material, a negative shunt electrode frame, a negative current collecting plate, and a negative battery end plate, which are stacked in sequence. The positive shunt electrode frame and the negative shunt electrode frame are respectively a flat plate, and a groove serving as an electrolyte flow channel is provided on the side of the flat plate close to the positive electrode and in contact with the positive electrode; A through hole serving as a positive electrolyte inlet and a through hole serving as a positive electrolyte outlet are provided on the positive shunt electrode frame. The positive electrolyte inlet is connected to the electrolyte flow channel on the positive shunt electrode frame, and the positive electrolyte inlet is connected to the positive electrolyte inlet on the positive side battery end plate. A through hole serving as a negative electrolyte inlet and a through hole serving as a negative electrolyte outlet are provided on the negative shunt electrode frame. The negative electrolyte inlet is connected to the electrolyte flow channel on the negative shunt electrode frame, and the negative electrolyte inlet is connected to the negative electrolyte inlet on the negative side battery end plate. The positive bus electrode frame and the negative bus electrode frame are respectively a flat plate, and a through hole serving as an electrolyte flow channel is provided in the contact area between the flat plate and the positive electrode; A through hole serving as a positive electrolyte outlet is provided on the positive bus electrode frame, the positive electrolyte outlet is connected to the through hole of the electrolyte flow channel on the positive bus electrode frame, and the positive electrolyte outlet is connected to the positive electrolyte outlet on the positive shunt electrode frame and the positive electrolyte outlet on the positive side battery end plate; A through hole serving as a negative electrolyte outlet is provided on the negative bus electrode frame, the negative electrolyte outlet is connected to the through hole of the electrolyte flow channel on the negative bus electrode frame, and the negative electrolyte outlet is connected to the negative electrolyte outlet on the negative shunt electrode frame and the negative electrolyte outlet on the negative side battery end plate; The positive and negative electrolytes flow into the positive shunt electrode frame and the negative shunt electrode frame respectively through the electrolyte inlets of the positive and negative battery end plates; the positive and negative electrolytes are distributed on the electrode surfaces of the positive and negative electrodes respectively, and penetrate into the electrodes along the normal direction of the electrode surfaces, and flow into the positive bus electrode frame and the negative bus electrode frame respectively after passing through the thickness direction of the electrodes, and finally flow out of the battery through the electrolyte outlets on the positive and negative battery end plates respectively; The positive shunt electrode frame between the positive current collecting plate and the positive electrode and the negative shunt electrode frame between the negative electrode and the negative current collecting plate in the battery structure are conductors.

2. The battery structure according to claim 1, characterized in that: Parts of the positive bus electrode frame and the negative bus electrode frame that are in contact with the positive electrode and the negative electrode, respectively, are conductive or non-conductive.

3. The battery structure according to claim 2, characterized in that: The portions of the positive bus electrode frame and the negative bus electrode frame that are in contact with the positive electrode and the negative electrode, respectively, are conductors.

4. The battery structure according to claim 1, characterized in that: The parts of the positive bus electrode frame and the negative bus electrode frame that are in contact with the positive electrode and the negative electrode respectively are made of non-porous material or porous material; the porosity of the porous material is 0.05-0.5 times the porosity of the electrode porous material.

5. The battery structure according to claim 4, characterized in that: The parts of the positive bus electrode frame and the negative bus electrode frame that are in contact with the positive electrode and the negative electrode respectively are made of porous material; the porosity of the porous material is 0.1-0.2 times the porosity of the electrode porous material.

6. The battery structure according to claim 1, characterized in that: The electrolyte flow channel is one or more of a serpentine flow channel and an interdigitated flow channel; The porous material electrode is one or more of carbon felt, carbon paper and carbon cloth.

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