Electrolyte flowing type battery cell and battery pack

Abstract

The utility model relates to an electrolyte flow type battery cell and a battery pack, and belongs to the field of electrochemical batteries. An independent liquid inlet and an independent liquid outlet are formed in the outer surface of a battery cell monomer of the electrolyte flowing type battery cell; the liquid inlet and the liquid outlet respectively form a passage with an inner cavity of the battery cell monomer; the liquid outlet is communicated with an inlet of the electrolyte tank, and the liquid outlet is communicated with an outlet of the electrolyte tank; the liquid inlet and the liquid outlet are respectively used for the inflow and outflow of electrolyte, the inflow and outflow of the electrolyte form an electrolyte flowing loop, and the electrolyte flowing loop is also provided with a flow meter and a liquid guide valve. According to the electrolyte flow type battery cell and the battery pack, a battery cell structure with internal electrolyte external circulation is adopted, the risk of thermal runaway of the battery cell is reduced, the risk of lithium precipitation caused by low-temperature charging of the battery is avoided, the battery capacity is improved, and the cycle life is prolonged.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemical cells, in particular to an electrolyte flowing type cell and battery pack. BACKGROUND

[0002] As a representative of electrochemical energy storage devices, lithium ion batteries have been widely used in power vehicles, energy storage, 3C and other fields due to their high energy density, long cycle life, environmental friendliness and other characteristics. While the energy density of lithium batteries is gradually increasing, accidents of fire and explosion caused by safety problems also occur frequently.

[0003] In the field of energy storage, the emergence of flow batteries makes up for the shortcomings of the safety of lithium ion batteries. The reason why flow batteries are safe is that the flowing electrolyte can continuously take away heat during the charging and discharging process, so that the battery system is not easy to heat runaway. However, the energy density is still far behind that of lithium batteries. The electrolyte in the lithium ion battery is enclosed in the single cell, and the heat generated during operation is easily accumulated in the cell, which leads to heat runaway.

[0004] Traditional electrochemical batteries, such as lithium ion batteries, remain completely closed to the outside after the liquid injection and formation manufacturing process, that is, the total amount of electrolyte remains constant during the entire use cycle of the battery. The traditional measures to avoid heat runaway of lithium batteries are usually based on the heat dissipation or heat distribution technology outside the cell monomer. However, the heat accumulation of lithium batteries occurs in the cell, so the external heat dissipation or heat insulation measures are like "itching the boot", which cannot solve the essential problem. CONTENT OF THE INVENTION

[0005] In order to solve the problems in the prior art, the present application provides an electrolyte flowing type cell and battery pack, which adopts an electrolyte flowing type cell structure, and through the outflow of electrolyte, a part of the heat in the battery is taken away, thereby avoiding heat runaway at the level of single cell.

[0006] To achieve the above purpose, the present application adopts the following technical solutions.

[0007] In a first aspect, the present application provides an electrolyte flowing type cell, wherein an independent liquid inlet and an independent liquid outlet are formed on the outer surface of the cell monomer of the electrolyte flowing type cell, the liquid inlet and the liquid outlet form a passage with the internal cavity of the cell monomer respectively; the liquid outlet is connected to the inlet of the electrolyte pool, and the liquid outlet is connected to the outlet of the electrolyte pool; the liquid inlet and the liquid outlet are used for inflow and outflow of electrolyte respectively, and the inflow and outflow of electrolyte form an electrolyte flowing loop, and the electrolyte flowing loop is further provided with a flow meter and a liquid guide valve.

[0008] The application adopts an electrolyte flowing type battery cell structure. Through the outflow of electrolyte, part of the heat in the battery is taken away, thereby avoiding the occurrence of thermal runaway at the level of single battery cell. Meanwhile, the injection of fresh normal temperature electrolyte can further reduce the heat generation of the battery cell and uniform the temperature of the battery cell. Furthermore, since the electrolyte in the system is flowing and replenishable, the replenishment of fresh electrolyte can play a role in improving the reaction activity and taking out by-products, which can significantly improve the cycle capacity of the battery and prolong the cycle life. The flow meter is used to control the inflow and outflow speed of the electrolyte. The inflow and outflow speed of the electrolyte can be adjusted within a certain range (for example, adjusted by a mass flow meter), and the inflow speed is preferably equal to the outflow speed. In addition, the flow rate of the electrolyte is controlled so as not to damage the charge and discharge performance of the battery itself, that is, it does not have a negative impact on the stability of the internal electrode interface.

[0009] As an optional embodiment, the liquid inlet coincides with the conventional liquid injection port of the battery cell monomer, and the liquid outlet coincides with the liquid injection port of the battery cell monomer.

[0010] That is, the conventional liquid injection port of the battery cell monomer adopted by the liquid inlet is used to flow the electrolyte, and the operation of re-opening the liquid inlet is omitted. In the prior art, the conventional liquid injection port of the battery cell monomer is used to inject electrolyte into the battery cell monomer. In the application, the liquid inlet for flowing electrolyte coincides with the conventional liquid injection port of the battery cell monomer, that is, the conventional liquid injection port of the battery cell monomer adopted by the liquid inlet is used to flow the electrolyte, and the operation of re-opening is omitted, and at the same time, the risk of liquid leakage caused by opening multiple liquid inlets on the surface of the battery cell monomer can also be avoided.

[0011] As an optional embodiment, the liquid outlet is arranged at the lower half or the top of the battery cell monomer in a normal placement state.

[0012] Optionally, the liquid outlet is arranged at the bottom of the battery cell monomer in a normal placement state.

[0013] Optionally, the liquid outlet is arranged at the side of the battery cell monomer in a normal placement state and close to the bottom.

[0014] As an optional embodiment, the liquid inlet is airtight connected with the liquid inlet pipe and communicated with the inside of the battery cell monomer to form an electrolyte flowing channel.

[0015] As an optional embodiment, the liquid outlet is airtight connected with the liquid outlet pipe and communicated with the inside of the battery cell monomer to form an electrolyte flowing channel.

[0016] As an optional embodiment, the liquid guide valve is arranged at the liquid inlet side and the liquid outlet side of the electrolyte flowing loop.

[0017] As an optional implementation, the liquid guide valve comprises a one-way liquid guide valve.

[0018] In the present application, the one-way liquid guide valve can avoid the problem of electrolyte backflow leading to electrolyte communication between different monomer cells, and ensure the one-way circulation of electrolyte in the monomer cells as much as possible.

[0019] As an optional implementation, the electrolyte flow type cell further comprises a pump located between the electrolyte pool and the liquid outlet pipe (such as the manifold connected with the liquid outlet pipe), for conveying the electrolyte in the cell monomer to the electrolyte pool.

[0020] As an optional implementation, the electrolyte flow loop further comprises a cooler or a heater for cooling or heating the electrolyte; the loop formed by cooling / heating the electrolyte by the cooler / heater is called a cooling / heating loop (i.e., a cooling loop or a heating loop).

[0021] As an optional implementation, the two ends of the liquid inlet pipe or the liquid outlet pipe are sealed with a sealing cap after the liquid injection and formation process or are connected in airtight manner with the cooling / heating loop.

[0022] In the present application, the electrolyte flow type cell should be kept isolated from the external environment after the liquid injection and formation process, so as to ensure the dry operating environment inside the cell. Before assembly, the liquid inlet pipe and the liquid outlet pipe are preferably sealed with a recyclable sealing cap. When connected with the cooling / heating loop, it should be ensured that all connections are airtight, and the connection operation should be carried out in a dry environment or a sealed environment. The replacement of the electrolyte pool should also avoid the entry of water vapor and impurities.

[0023] As an optional implementation, the electrolyte flow loop is provided with an impurity filtering and collecting device.

[0024] In the present application, in order to avoid the influence of by-products on the performance of the cell, an impurity filtering and collecting device is arranged in the electrolyte flow loop, which removes the by-products from the electrolyte flow loop, so as to avoid their re-entry into the cell and affect the performance of the cell.

[0025] As an optional implementation, the impurity filtering and collecting device is located on the liquid outlet side.

[0026] As an optional implementation, the liquid inlet pipe or the liquid outlet pipe adopts a hard pipe or a soft pipe, preferably a soft pipe that does not affect the assembly of the cell module.

[0027] As an optional implementation, the cell comprises a square cell.

[0028] As an optional implementation, the capacity of the cell is more than 5 Ah, preferably more than 50 Ah.

[0029] As an optional embodiment, the types of the battery cell include lithium ion battery, sodium ion battery, zinc ion battery, aluminum ion battery, etc., preferably lithium ion battery and sodium ion battery.

[0030] In a second aspect, the application further provides an electrolyte flow type battery pack, which comprises a plurality of the above-mentioned electrolyte flow type battery cells.

[0031] As an optional embodiment, the battery pack further comprises a flow pipe, which is located at the inlet side or / and outlet side of the electrolyte flow loop.

[0032] As an optional embodiment, the number of the flow pipe located at the inlet side of the electrolyte flow loop is at least 1.

[0033] As an optional embodiment, the number of the flow pipe located at the outlet side of the electrolyte flow loop is at least 1.

[0034] As an optional embodiment, at the inlet side, the flow pipe is connected with the inlet pipe and the cooling / heating loop located at the inlet side, respectively; at the outlet side, the flow pipe is connected with the outlet pipe and the cooling / heating loop located at the outlet side, respectively.

[0035] As an optional embodiment, the liquid guide valve is located between the flow pipe and the inlet pipe / outlet pipe (i.e. inlet pipe or outlet pipe).

[0036] As an optional embodiment, a switch is arranged in the flow pipe or the liquid guide valve.

[0037] The electrolyte flow type battery cell and battery pack provided by the application adopt the electrolyte flow type battery cell structure, which can ensure that the inside of the battery cell and the external natural environment are always in an isolated state, but the electrolyte can be output from the single battery to the electrolyte pool and fresh electrolyte can be supplemented from the electrolyte pool to form a closed loop. When the battery temperature is higher than the upper limit of the safe temperature range, the electrolyte flow can take away part of the heat to avoid heat accumulation, and the normal temperature electrolyte re-injected after natural cooling or through the cooler can further reduce the temperature of the battery cell, and at the same time, play a role in uniformizing the temperature difference between the battery cell monomers and the battery cell modules (or battery pack), thereby ensuring the thermal safety of the battery at the most fundamental level of the battery cell monomer. When the battery temperature is lower than the lower limit of the safe temperature range, the electrolyte is extracted and heated to a suitable temperature by a heater, and then re-injected into the battery cell monomer, which can effectively avoid the occurrence of lithium precipitation in the low-temperature charging process, and further avoid the occurrence of short circuit and the risk of fire and explosion.

[0038] In the application, the above technical features can be freely combined to form new technical solutions without conflict.

[0039] The above technical solutions provided by the application have the following advantages compared with the prior art.

[0040] (1) The electrolyte flow type battery cell and battery pack provided by the application adopt a battery cell structure with internal electrolyte external circulation. The electrolyte flow takes away part of the heat, and the cooled electrolyte (for example, normal temperature electrolyte) is injected into the battery cell to further reduce the heat generation of the battery cell and uniform the temperature difference of the battery cell, thereby reducing the risk of thermal runaway of the battery cell;

[0041] (2) When the temperature is low, the electrolyte flows and is heated to a suitable temperature by the heater, avoiding the risk of lithium precipitation generated by low-temperature charging of the battery;

[0042] (3) Fresh electrolyte injected into the battery cell can enhance the battery reaction activity and take away by-products, thereby improving the capacity of the battery and prolonging the cycle life of the battery;

[0043] (4) The cooling / heating circuit adopted by the application can replace the liquid cooling system in the current battery pack, so that the additional volume, weight and cost of the battery pack are almost not increased;

[0044] (5) The electrolyte flow type battery cell or battery pack provided by the application greatly reduces the safety risk of thermal runaway and short circuit of lithium batteries without affecting the existing energy density, production process, module assembly process and cost of the battery, and has high industrial feasibility. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a schematic view of an electrolyte flow type battery cell in the application;

[0046] Figure 2 is a schematic view of an electrolyte flow type battery cell in the application and the connection of the inlet and outlet liquid pipes;

[0047] Figure 3 is a schematic view of a sealing cover for an electrolyte flow type battery cell in the application;

[0048] Figure 4 is a schematic view of an electrolyte flow type battery pack in the application;

[0049] Figure 5 is a schematic view of another electrolyte flow type battery pack in the application;

[0050] Figure 6 is a graph showing the change trend of the center temperature of the battery cell with cycles;

[0051] Figure 7 is a graph showing the change trend of the maximum temperature difference in the battery cell and between the battery cells with cycles. DETAILED DESCRIPTION

[0052] In order to make the objectives, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of the present application.

[0053] Unless otherwise specifically defined, the terms used herein are to be understood as having a meaning that is consistent with their use in the relevant art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. If there is a conflict between the present specification and the definitions of terms, the present specification prevails.

[0054] Unless otherwise specifically noted, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0055] Some embodiments of the present application provide an electrolyte flow type battery cell, as shown in Figure 1 The outer surface of the battery cell monomer of the electrolyte flow type battery cell is provided with an independent liquid inlet and an independent liquid outlet, the liquid inlet and the liquid outlet form a passage with the internal cavity of the battery cell monomer, respectively; the liquid outlet is connected to the inlet of the electrolyte pool, and the liquid outlet is connected to the outlet of the electrolyte pool; the liquid inlet and the liquid outlet are used for the inflow and outflow of electrolyte, respectively, and the inflow and outflow of electrolyte form an electrolyte flow loop, and the electrolyte flow loop is provided with a flow meter and a liquid guide valve. In order to avoid opening a new opening on the outer surface of the battery cell monomer, the liquid inlet coincides with the conventional liquid injection port of the battery cell monomer.

[0056] In some embodiments, the liquid inlet is airtight connected with the liquid inlet pipe and communicates with the internal cavity of the battery cell monomer to form an electrolyte flow passage, and the liquid outlet is airtight connected with the liquid outlet pipe and communicates with the internal cavity of the battery cell monomer to form an electrolyte flow passage, and the liquid outlet is arranged at a position of the lower half of the battery cell monomer in a normal placement state. As shown in Figure 2 The liquid outlet is arranged at a position close to the bottom of the side surface of the battery cell monomer in a normal placement state.

[0057] In some embodiments, as shown in Figure 3 The two ends of the liquid inlet pipe and the liquid outlet pipe are sealed by using a sealing cover after the battery cell is liquidized.

[0058] In some embodiments, the electrolyte flow loop is further provided with a cooler or a heater, as shown in Figure 4As shown, it is used to cool or heat the electrolyte; the circuit formed by heating / cooling the electrolyte through a cooler / heater is called a cooling / heating circuit; the electrolyte flow circuit is also equipped with a pump, which is located between the outlet pipe and the electrolyte pool, as shown. Figure 4 As shown.

[0059] Some embodiments of this application provide an electrolyte flow type battery pack, the battery pack including a plurality (e.g., n) of the above-mentioned electrolyte flow type cells, wherein the cell includes a manifold located on the inlet side and / or outlet side of the electrolyte flow circuit, a liquid guiding valve disposed on the inlet side and outlet side of the electrolyte flow circuit, preferably a unidirectional liquid guiding valve; a pump located between the electrolyte pool and the outlet pipe (e.g., the manifold connected to the outlet pipe); optionally, it also includes a cooler / heater (i.e., a cooler or heater) located between the manifold (e.g., the manifold on the inlet side) and the electrolyte pool.

[0060] like Figure 4 As shown, taking a battery pack (with one or more individual cells) as an example, the electrolyte flows out from the outlet pipe of the individual cell, enters the outlet manifold through a one-way guide valve, and then flows into the electrolyte pool after being pumped to generate flow potential energy. Based on the real-time battery temperature, the system selects whether to activate the cooler or heater. The cooled or heated electrolyte is then reinjected into the individual cell through the inlet manifold. One-way guide valves are preferably used on both the inlet and outlet sides to avoid electrolyte backflow that could cause electrolyte interconnection between different individual cells, thus ensuring unidirectional circulation of the electrolyte within the individual cells as much as possible.

[0061] In some embodiments, a switch is provided in the manifold or the liquid-conducting valve to allow flow through part or all of the pipes, thereby controlling the flow of electrolyte in individual or all individual cells.

[0062] In some implementations, the number of manifolds is at least one. For example, there can be 1 to N manifolds, where N corresponds to the number of individual battery cells in the module. When the electrolyte of one or more battery cells in the module needs to be controlled separately, different numbers of manifolds can be used. Figure 4 An electrolyte-flow battery pack using a single manifold was demonstrated. Figure 5 This paper illustrates a scenario for a battery pack using N manifolds to individually control the electrolyte flow of each cell. Specifically, each cell has a manifold on both the inlet and outlet sides, and each cell has a pump and an electrolyte pool on the outlet side. Optionally, each cell has a cooler / heater (i.e., a cooler or heater) on the inlet side.

[0063] The electrolyte flow type battery cell proposed in the present application should be kept isolated from the external environment at all times after the liquid injection and formation process, thereby ensuring a dry operating environment inside the battery cell. Before assembly, the inlet and outlet pipes of the single battery cell are preferably sealed using a recyclable sealing cap. When connected to the cooling / heating circuit, it should be ensured that all connections are airtight and that the connection operation is carried out in a dry or sealed environment. Subsequent replacement of the electrolyte pool should also avoid the entry of water vapor and impurities.

[0064] Example 1

[0065] This example uses two 10 Ah lithium iron phosphate square cell batteries in series to simulate the operating state of a lithium ion battery pack. The electrolyte inlet and outlet are both set on the top surface of the single battery. The electrolyte of each battery flows out through the outlet pipe and is connected to a Long-pump YZ155x pump, which is then driven to flow into the respective electrolyte pool and then re-injected into the single battery. The pump speed is set to 15 RPM, and the electrolyte is a new Zhongshun lithium iron phosphate electrolyte. The total positive and total negative (i.e., total positive and total negative) of the series-connected battery pack are connected to the battery pack charge and discharge test equipment.

[0066] The temperature measurement points for the battery cell temperature uniformity test are set on the surface of the 1st battery cell on the side of the contact between the 1st and 2nd battery cells. The temperature measurement points 1-5 correspond to the center point, upper left, upper right, lower left, and lower right, respectively. The temperature measurement points 6 and 7 for the temperature difference test between the battery cells are set at the center points of the side surfaces of the 1st and 2nd battery cells.

[0067] Comparative Example 1

[0068] This example uses two 10 Ah lithium iron phosphate square cell batteries in series to simulate the operating state of a lithium ion battery pack. The total positive and total negative of the series-connected battery pack are connected to the battery pack charge and discharge test equipment. The temperature measurement points for the battery cell temperature uniformity test are set on the surface of the 1st battery cell on the side of the contact between the 1st and 2nd battery cells. The temperature measurement points 1-5 correspond to the center point, upper left, upper right, lower left, and lower right, respectively. The temperature measurement points 6 and 7 for the temperature difference test between the battery cells are set at the center points of the side surfaces of the 1st and 2nd battery cells.

[0069] The battery pack of the example and the battery pack of the comparative example were subjected to charge and discharge tests, and the test environment temperature was 25°C. The test procedure was as follows: ① charge at a rate of 1C to 3.7C, constant voltage to 0.02C, and stand for 5 minutes; ② discharge at a rate of 1.5C to 2.8V, and stand for 5 minutes; ③ repeat steps ① and ② 100 times. Table 1 shows the test data of the battery cells of the example and the comparative example. According to the experimental results in Table 1, the trend graphs of the center temperature of the single battery cell, the maximum temperature difference inside the battery cell, and the temperature difference between the battery cells with the number of cycles are shown in FIGS. Figure 6 and Figure 7 ​

[0070] Table 1 Test data of the cells of the examples and the comparative examples

[0071]

[0072] The central temperature of the cells of the examples is significantly reduced by about 10°C compared to the cells of the comparative examples, and the change with the cycle is small. In addition, the maximum temperature difference inside the single cells of the examples is only 0-2°C, while the temperature difference of the single cells of the comparative examples exceeds 10°C at the end of the cycle; the temperature difference between the cells can reach 6°C in the comparative examples, while the temperature difference between the cells of the examples is only 1°C at most.

[0073] The above results fully demonstrate that even without connecting a cooling system, the electrolyte flowing type cell has a significant effect on reducing the temperature inside the cell, the temperature difference inside the single cells, and the temperature difference between the cells.

[0074] The above description is merely illustrative of the application and is not intended to limit the scope of the application. Various modifications to the embodiments described herein will be readily apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Thus, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrolyte flow-through cell, characterized by comprising: The outer surface of the cell monomer of the electrolyte flow type cell is provided with an independent liquid inlet and an independent liquid outlet, the liquid inlet and the liquid outlet form a passage with the internal cavity of the cell monomer respectively; the liquid outlet is connected with the inlet of the electrolyte pool, and the liquid outlet is connected with the outlet of the electrolyte pool; the liquid inlet and the liquid outlet are respectively used for inflow and outflow of electrolyte, and the inflow and outflow of electrolyte form an electrolyte flow loop, and the electrolyte flow loop is further provided with a flow meter and a liquid guide valve.

2. The electrolyte flow type cell according to claim 1, wherein, the liquid inlet coincides with the conventional liquid injection port of the cell monomer, and the liquid outlet coincides with the liquid injection port of the cell monomer; or / and the liquid outlet is arranged at the lower half or the top of the cell monomer in the normal placement state; or / and the liquid inlet is connected with the liquid inlet pipe in airtightness, and is communicated with the internal cavity of the cell monomer to form an electrolyte flow passage; the liquid outlet is connected with the liquid outlet pipe in airtightness, and is communicated with the internal cavity of the cell monomer to form an electrolyte flow passage; or / and the liquid guide valve is arranged at the liquid inlet side and the liquid outlet side of the electrolyte flow loop.

3. The electrolyte flow type cell according to claim 2, wherein, the electrolyte flow type cell further comprises a pump between the electrolyte pool and the liquid outlet pipe, for conveying the electrolyte in the cell monomer to the electrolyte pool; or / and the electrolyte flow loop is further provided with a cooler and / or a heater for cooling or heating the electrolyte; the loop formed by heating / cooling the electrolyte through the cooler / heater is called a cooling / heating loop; or / and impurity filtering and collecting devices are arranged in the electrolyte flow loop; or / and the liquid guide valve comprises a one-way liquid guide valve.

4. The flow-by electrolyte cell of claim 3, wherein The two ends of the liquid inlet pipe or the liquid outlet pipe are sealed by a sealing cap after the cell is liquidized, or are connected with the cooling / heating loop in airtightness; or the impurity filtering and collecting devices are arranged at the liquid outlet side.

5. The electrolyte flow type cell according to any one of claims 2-4, wherein, the liquid inlet pipe or the liquid outlet pipe adopts a hard pipe or a soft pipe.

6. The electro-lytic flow-through cell according to any one of claims 1 to 4, characterized in that the cell monomer comprises a square cell monomer; or / and the capacity of the cell monomer is more than 5 Ah; or / and the cell monomer includes lithium ion batteries, sodium ion batteries, zinc ion batteries and aluminum ion batteries.

7. An electrolyte flow cell battery characterized by the battery pack comprises a plurality of electrolyte flow type cells according to any one of claims 1-6.

8. The flow-through electrolytic cell stack of claim 7, wherein, the battery pack further comprises a busbar, and the busbar is arranged at the liquid inlet side or / and the liquid outlet side of the electrolyte flow loop.

9. The flow-through electrolytic cell stack of claim 8, wherein, The number of busbars arranged at the liquid inlet side of the electrolyte flow loop is at least one, and the number of busbars arranged at the liquid outlet side of the electrolyte flow loop is at least one.

10. The flow-through electrolytic cell stack according to claim 8 or 9, characterized in that the busbar is connected with the liquid inlet pipe and the cooling / heating loop at the liquid inlet side respectively, and is connected with the liquid outlet pipe and the cooling / heating loop at the liquid outlet side respectively; or / and switches are arranged in the busbar or the liquid guide valve in the battery pack.

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