Battery with electrolyte balancing device and battery pack

Abstract

The utility model provides a battery with an electrolyte balancing device and a battery pack, and the battery comprises a battery shell, the battery shell comprises a body and a top cover, a first cavity is defined by the body and the top cover, and electrolyte is filled in the first cavity; the battery cell is arranged in the first cavity; and the electrolyte balancing device comprises a device shell, a second cavity is formed in the device shell, the second cavity is filled with balancing liquid, and the second cavity communicates with the first cavity. According to the utility model, on one hand, the concentration change speed of the electrolyte can be slowed down by increasing the capacity of the electrolyte, and on the other hand, the concentration of the electrolyte can be kept in a stable state within a certain time by supplementing equilibrium liquid into the first cavity, so that the cycling stability of the battery is maintained. Compared with conventional technologies such as material modification or electrolyte optimization, the battery has the advantages of low research and development cost, simple structure, convenience in installation, wide application range, capability of quickly balancing the stability of the battery and the like.

Description

Technical Field

[0001] The utility model relates to the technical field of batteries, in particular to a battery and a battery pack with an electrolyte balancing device. Background Art

[0002] Electrochemical batteries, especially those based on the rocking-chair ion insertion and extraction reaction mechanism, have received great attention in the field of energy storage due to their high conversion efficiency and flexible assembly characteristics, and have begun commercialization. Among these batteries, maintenance-free lead-acid batteries have been widely used, especially in uninterruptible power supply (UPS) systems. However, lead-acid batteries face many challenges, including sensitivity to temperature changes, short life, and environmental pollution issues, which are partly due to the manufacturing and recycling processes of lead-acid batteries. In addition, the reaction properties of the positive and negative electrodes of lead-acid batteries with the electrolyte limit their cycle life.

[0003] In recent years, aqueous electrolytes have become a research hotspot for energy storage batteries due to their neutral pH value and environmentally friendly characteristics. This type of battery is theoretically safer and more environmentally friendly. However, the narrow electrochemical window of water makes it difficult to avoid the decomposition reaction of water during the floating charge process of aqueous batteries, which will cause changes in the pH value of the positive and negative electrode surfaces of the battery, thereby affecting the cycle stability of the battery. At the same time, the accumulation of salt in the electrolyte and the decomposition of water will also lead to changes in the electrolyte concentration, increasing the risk of salt precipitation and rupture of the battery.

[0004] In order to solve these problems, researchers have done a lot of work on active material modification and electrolyte optimization. These improvements have improved the performance of the battery to a certain extent. However, such solutions have high technical costs, great research and development difficulties, and the effects are not stable. Therefore, how to effectively improve the floating charge life of the battery by improving the internal structure of the aqueous battery has become a new idea for battery development and optimization at this stage. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problems of easy electrolysis of aqueous electrolytes and unstable electrolyte concentration in the prior art, and to provide a battery and a battery pack with an electrolyte balancing device.

[0006] To solve the above technical problems, the utility model provides a battery with an electrolyte balancing device, comprising: a battery shell, the battery shell comprising a main body and a top cover, one side of the main body is provided with an opening, the top cover covers the main body opening, and together with the main body, a first cavity is enclosed, and electrolyte is filled in the first cavity; a battery cell, the battery cell is arranged in the first cavity; an electrolyte balancing device, the electrolyte balancing device is connected to the battery shell, and comprises a device shell, a second cavity is provided inside the device shell, the second cavity is filled with balancing liquid, and the second cavity is connected to the first cavity.

[0007] In one embodiment of the present utility model, the battery housing further comprises an outer edge, the outer edge is connected to the body and protrudes from the body in a horizontal direction, and the electrolyte balancing device is connected to the outer edge.

[0008] In an embodiment of the present utility model, a first docking portion is provided on the outer edge, and a second docking portion is provided on the device housing, and the first docking portion and the second docking portion are plugged into each other.

[0009] In one embodiment of the present invention, in the height direction of the battery, at least a portion of the second cavity is higher than the first cavity.

[0010] In one embodiment of the present invention, the electrolyte balancing device further includes a semipermeable membrane, and the semipermeable membrane is disposed at a point where the first cavity and the second cavity are connected.

[0011] In one embodiment of the present invention, the electrolyte balancing device further comprises a semipermeable membrane capsule, the semipermeable membrane capsule is disposed inside the second cavity, and the balancing liquid is filled in the semipermeable membrane capsule.

[0012] In one embodiment of the present invention, the balancing liquid is deionized water or an electrolyte.

[0013] In one embodiment of the utility model, a first liquid injection hole is provided on the top cover, and the first liquid injection hole is connected to the internal and external environment of the first cavity. A second liquid injection hole is provided on the device shell, and the second liquid injection hole is connected to the internal and external environment of the second cavity.

[0014] In one embodiment of the utility model, the battery cell includes a positive electrode sheet, a positive current collector, a negative electrode sheet, a negative current collector and a separator, and the adjacent positive electrode sheets and the negative electrode sheets are respectively arranged on both sides of the thickness direction of the separator, the positive electrode sheet is electrically connected to the positive current collector, and the negative electrode sheet is electrically connected to the negative current collector.

[0015] The utility model also provides a battery pack, which comprises at least two batteries with electrolyte balancing devices, and the battery shells of two adjacent batteries with electrolyte balancing devices are connected.

[0016] The above technical solution of the utility model has the following advantages compared with the prior art:

[0017] The battery and battery pack with electrolyte balancing device described in the utility model are provided with electrolyte balancing device on the conventional battery shell structure, which can slow down the concentration change rate by increasing the electrolyte capacity, and on the other hand, can keep the concentration of electrolyte stable within a certain period of time by adding balancing liquid to the first cavity, thereby maintaining the cycle stability of the battery. Compared with conventional technologies such as material modification or electrolyte optimization, this application has the advantages of low R&D cost, simple structure, easy installation, wide application range and rapid balancing of battery stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to make the content of the utility model more clearly understood, the utility model is further described in detail below based on specific embodiments of the utility model in combination with the accompanying drawings.

[0019] Figure 1 It is a structural schematic diagram of a battery pack with an electrolyte balancing device in a preferred embodiment of the utility model;

[0020] Figure 2 It is a schematic diagram of a conventional battery structure in the prior art;

[0021] Figure 3 It is a structural schematic diagram of a battery pack with an electrolyte balancing device in the second embodiment of the utility model;

[0022] Figure 4 It is a structural schematic diagram of a battery pack with an electrolyte balancing device in the third embodiment of the utility model;

[0023] Figure 5 It is the change of battery capacity under the battery float charge test in the comparative example and embodiments 1 to 3.

[0024] Explanation of the reference numerals in the specification: 100, battery casing; 110, main body; 120, outer edge; 121, first docking portion; 130, first cavity; 140, top cover; 141, injection hole; 150, battery cell; 200, electrolyte balance device; 210, device casing; 211, second docking portion; 212, second injection hole; 220, second cavity; 230, semipermeable membrane; 240, semipermeable membrane capsule. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0026] Embodiment 1

[0027] See also Figure 1 As shown, this embodiment provides a battery pack with an electrolyte balancing device 200, which includes two batteries with electrolyte balancing devices 200, the battery housings 100 of the two adjacent batteries with electrolyte balancing devices 200 are connected, and the structural settings of the two batteries are the same, and any battery with an electrolyte balancing device 200 includes: a battery housing 100, the battery housing 100 includes a body 110 and a top cover 140, one side of the body 110 is provided with an opening, and the top cover 140 covers the opening of the body 110 , and together with the body 110, a first cavity 130 is enclosed, and the electrolyte is filled in the first cavity 130; a battery cell 150, the battery cell 150 is arranged in the first cavity 130; an electrolyte balancing device 200, the electrolyte balancing device 200 is connected to the battery shell 100, and includes a device shell 210, and a second cavity 220 is arranged inside the device shell 210, and the second cavity 220 is filled with a balancing liquid, and the second cavity 220 is connected to the first cavity 130.

[0028] The battery with electrolyte balancing device 200 described in this embodiment is provided with electrolyte balancing device 200 on the structure of conventional battery housing 100. On the one hand, the concentration change rate of the electrolyte can be slowed down by increasing the electrolyte capacity. On the other hand, the concentration of the electrolyte can be kept stable within a certain period of time by adding balancing liquid to the first cavity 130, thereby maintaining the cycle stability of the battery. Compared with conventional technologies such as material modification or electrolyte optimization, this application has the advantages of low R&D cost, simple structure, easy installation, wide application range, and rapid balancing of battery stability.

[0029] It should be noted that Figure 2 The conventional battery structure shown is a reference. The opening of the battery housing 100 is set at its top, and the outer edge 120 extends horizontally outward from the opening of the battery housing 100. Based on this structure, the space between the outer edge 120 and the side wall of the battery housing not only increases the overall volume after assembly, but also usually cannot be fully utilized, thereby causing space waste in the battery structure. Based on this, the present application sets the electrolyte balancing device 200 below the outer edge 120 of the battery and connects it to the outer edge 120 to fill the space between the outer edge 120 and the side wall of the battery housing in the conventional structure, thereby achieving the effect of improving the space utilization of the battery structure while balancing the electrolyte.

[0030] See also Figure 1 As shown, any battery with an electrolyte balancing device 200 in this embodiment is preferably a square battery, the first cavity 130 is filled with an aqueous electrolyte, the opening of the body 110 is set upward for easy installation, the top cover 140 can be correspondingly engaged at the opening, and the opening is sealed, the top cover 140 is provided with a first injection hole 141, the first injection hole 141 is connected to the internal and external environment of the first cavity 130, and the aqueous electrolyte enters the first cavity 130 through the first injection hole 141. In this embodiment, the battery cell 150 includes a positive electrode sheet, a positive current collector, a negative electrode sheet, a negative current collector and a diaphragm, and the adjacent positive electrode sheets and the negative electrode sheets are respectively arranged on both sides of the thickness direction of the diaphragm, the positive electrode sheet is electrically connected to the positive current collector, and the negative electrode sheet is electrically connected to the negative current collector. Further, the positive electrode sheet and the negative electrode sheet in this embodiment are preferably self-supporting flexible thick electrodes, wherein the positive electrode sheet substrate includes a Prussian blue compound and a conductive agent. The negative electrode substrate includes a polyanion material and a conductive agent. Among them, the Prussian blue compound includes a Prussian blue compound with the general formula AxM1c[Fe(CN)6]y·zH2O, wherein A is one or more of Li, Na, K, Ca, Mg, Zn and Al, M1 is one or more of Fe, Co, Ni, Cu, Zn, Ti, V, Cr, Mn, 0≤x≤2, 0≤y≤1, 0≤c≤1, 0≤z≤16; the conductive agent is selected from at least one of graphite, carbon nanotubes, Ketjen black and acetylene black; the polyanion material is selected from at least one of sodium titanium phosphate, sodium titanium manganese phosphate and sodium zirconium manganese phosphate.

[0031] Furthermore, the battery housing 100 further includes an outer edge 120, the outer edge 120 is connected to the body 110 and protrudes from the body 110 in the horizontal direction, and the electrolyte balancing device 200 is connected to the outer edge 120, thereby achieving the purpose of fully utilizing the battery space. Specifically, the outer edge 120 in this embodiment is provided with a first docking portion 121, and the device housing 210 is provided with a second docking portion 211, and the first docking portion 121 and the second docking portion 211 are plugged into each other, thereby connecting the electrolyte balancing device 200 to the body 110. In this embodiment, the width of the electrolyte balancing device 200 does not exceed the extension length of the outer edge 120, thereby not increasing the battery volume.

[0032] Further, after the electrolyte balancing device 200 is connected, it fits tightly with the body 110 and is connected to each other. In this embodiment, the body 110 and the device housing 210 of the electrolyte balancing device 200 are integrally arranged to achieve the connection between the two. In other embodiments, the connection effect can also be achieved by punching holes on the surface of the body 110 at corresponding positions, and the utility model does not impose specific restrictions on this. Further, the balancing liquid in this embodiment is the electrolyte in the first cavity 130, thereby increasing the electrolyte capacity inside the battery to achieve the purpose of slowing down the speed of its concentration change.

[0033] Further, in the height direction of the battery, at least part of the second cavity 220 is higher than the first cavity 130. Based on this structural setting, at least part of the second cavity 220 is higher than the first cavity 130, thereby ensuring that in the height direction of the battery, the electrolyte in the second cavity 220 can flow to the first cavity 130 under the action of the osmotic pressure difference. The device housing 210 in this embodiment is provided with a second injection hole 212, and the second injection hole 212 communicates with the internal and external environments of the second cavity 220, and the balancing liquid enters the second cavity 220 through the second injection hole 212.

[0034] Embodiment 2

[0035] See also Figure 3 As shown, this embodiment includes another battery pack with an electrolyte balancing device 200, which includes two batteries with electrolyte balancing devices 200 connected to each other, and the two batteries have the same structural arrangement, wherein in any one of the batteries with the electrolyte balancing device 200, only the internal structure of the electrolyte balancing device 200 is different from that in the first embodiment, specifically:

[0036] In this embodiment, the electrolyte balancing device 200 further includes a semipermeable membrane 230, which is disposed at the connection between the first cavity 130 and the second cavity 220. Specifically, the internal balancing liquid of the second cavity 220 in this embodiment is deionized water, and the semipermeable membrane 230 is preferably a selective permeable membrane, which can only pass water molecules but not other ions. Specifically, its permeation flux is 1-5L / (m2·h), and the rejection rate for sodium ions and sulfate ions is greater than 99%. Based on this, when the electrolyte balancing device 200 is connected to the battery housing 100, the deionized water inside it can flow from the second cavity 220 toward the first cavity 130, thereby achieving dilution of the electrolyte concentration to achieve balance of the electrolyte concentration.

[0037] Embodiment 3

[0038] This embodiment provides a third battery pack with an electrolyte balancing device 200, which includes two batteries with electrolyte balancing devices 200 connected to each other, and the two batteries have the same structural arrangement. Among them, only the working principle of the electrolyte balancing device 200 in any one of the batteries with the electrolyte balancing device 200 is the same as that in the second embodiment, and no further details are given here. This embodiment is only different from the second embodiment in internal structure arrangement, specifically:

[0039] See also Figure 4 As shown, since the process of the semipermeable membrane 230 structure in the actual installation process is relatively complicated, a semipermeable membrane capsule 240 is used in this embodiment to replace the semipermeable membrane 230 structure in the second embodiment to reduce the complexity of its assembly. The balancing liquid in this embodiment is preferably deionized water, and the electrolyte balancing device 200 also includes a semipermeable membrane capsule 240, which is arranged inside the second cavity 220, and the balancing liquid is filled in the semipermeable membrane capsule 240. Deionized water needs to be injected into the semipermeable membrane capsule 240 before use, and when assembling the battery, only the head mold capsule needs to be placed inside the second cavity 220.

[0040] Comparative Example

[0041] The present application performs a float charge test on a conventional battery pack of 53Ah and a battery pack with an electrolyte balancing device in Examples 1 to 3 of the same capacity. The specific test process is as follows: after the above battery pack is activated, it is float charged at 1.65V for 28 days, and then the capacity is calibrated by 0.1C charge and discharge. After long-term cycling, the capacity calibration change curve of each battery pack is obtained. For details, see Figure 5 As shown, it can be seen from the capacity calibration change curve that the battery capacity of the conventional battery pack decays in a "cliff-like" manner, while the battery pack capacity in Examples 1 to 3 shows an overall uniform and slow downward trend, but can still maintain a relatively stable battery capacity. Based on this result, the present application disassembles the conventional battery pack and finds that the main reason for its sudden drop in capacity is that the volatilization of water in the battery causes uneven concentration distribution inside the electrolyte, which in turn causes failure due to different charge and discharge depths of electrodes in different parts. In comparison, the battery pack with an electrolyte balancing device in Examples 1 to 3 has a significantly improved service life under the same number of cycles due to the provision of an electrolyte balancing device. The reason for this is mainly that although water decomposition occurs during the floating charge process, the degree of change in the electrolyte concentration is affected by the balancing liquid inside the electrolyte balancing device and is in a stable state as a whole, thereby causing the cycle life of the corresponding battery pack to not change significantly.

[0042] In summary, the battery, battery pack and electrical equipment with electrolyte balancing device 200 described in the utility model are provided with electrolyte balancing device 200 on the conventional battery housing 100 structure. On the one hand, the concentration change rate of the electrolyte can be slowed down by increasing the electrolyte capacity, and on the other hand, the concentration of the electrolyte can be kept stable within a certain period of time by adding balancing liquid to the first cavity 130, thereby maintaining the cycle stability of the battery. Compared with conventional technologies such as material modification or electrolyte optimization, this application has the advantages of low R&D cost, simple structure, easy installation, wide application range and rapid balancing of battery stability.

[0043] Obviously, the above embodiments are merely examples for the purpose of clear explanation and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from these are still within the scope of protection of the invention of the utility model.

Claims

1. A battery with an electrolyte balancing device, characterized in that: include: A battery casing, the battery casing comprising a body and a top cover, the body having an opening on one side, the top cover sealing the body opening and surrounding a first cavity with the body, wherein the electrolyte is filled in the first cavity; A battery cell, wherein the battery cell is disposed in the first cavity; An electrolyte balancing device is connected to the battery housing and comprises a device shell, a second cavity is provided inside the device shell, the second cavity is filled with a balancing liquid, and the second cavity is connected to the first cavity.

2. The battery with an electrolyte balancing device according to claim 1, characterized in that: The battery housing further comprises an outer edge, which is connected to the body and protrudes from the body in a horizontal direction, and the electrolyte balancing device is connected to the outer edge.

3. The battery with an electrolyte balancing device according to claim 2, characterized in that: A first docking portion is provided on the outer edge, and a second docking portion is provided on the device housing, and the first docking portion and the second docking portion are plugged into each other.

4. The battery with an electrolyte balancing device according to claim 1, characterized in that: In the height direction of the battery, at least a portion of the second cavity is higher than the first cavity.

5. The battery with an electrolyte balancing device according to claim 1, characterized in that: The electrolyte balancing device further includes a semipermeable membrane, and the semipermeable membrane is arranged at a point where the first cavity and the second cavity are connected.

6. The battery with an electrolyte balancing device according to claim 1, characterized in that: The electrolyte balancing device further comprises a semipermeable membrane capsule, which is arranged inside the second cavity and filled with the balancing liquid.

7. The battery with an electrolyte balancing device according to claim 1, characterized in that: The balancing solution is deionized water or an electrolyte.

8. The battery with an electrolyte balancing device according to claim 1, characterized in that: The top cover is provided with a first liquid injection hole, the first liquid injection hole is connected to the internal and external environment of the first cavity, and the device shell is provided with a second liquid injection hole, the second liquid injection hole is connected to the internal and external environment of the second cavity.

9. The battery with an electrolyte balancing device according to claim 1, characterized in that: The battery cell includes a positive electrode sheet, a positive current collector, a negative electrode sheet, a negative current collector and a separator. The adjacent positive electrode sheets and the negative electrode sheets are respectively arranged on both sides of the separator in the thickness direction. The positive electrode sheet is electrically connected to the positive current collector, and the negative electrode sheet is electrically connected to the negative current collector.

10. A battery pack, characterized in that: The invention comprises at least two batteries with electrolyte balancing devices according to any one of claims 1 to 9, wherein the battery shells of two adjacent batteries with electrolyte balancing devices are connected.

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