A connection device for a power battery

Abstract

The present invention relates to a connection device for a battery system, and the connection device has the following characteristics: the connection device is an independent connection component, which is used in series with a power battery, and the power battery loop current passes through the connection device; the connection device has a mechanism for cutting off the power battery loop current; the connection device is connected to the gas pressure component inside the device through a power battery voltage sampling component, and when the power battery voltage is abnormal, the gas pressure inside the connection device rises and actively disconnects the power battery loop current. Through the technical solution of the present invention, safety problems caused by overcharging of the power battery can be prevented, and the safety performance of the power battery can be improved.

Description

Technical Field

[0001] The invention relates to a connection device for a power battery, belonging to the technical field of batteries. Background Art

[0002] With the development of modern society and the enhancement of people's environmental awareness, more and more devices choose to use rechargeable secondary batteries as power sources, such as mobile phones, laptops, power tools and electric vehicles, etc., which provides broad space for the application and development of rechargeable secondary batteries.

[0003] Electric vehicles and energy storage power stations generally require high-capacity secondary batteries as their power source. In addition to high specific energy, these batteries must also offer excellent safety and a long cycle life to meet usage standards and meet consumer needs.

[0004] When secondary batteries, especially lithium-ion batteries, are overcharged, excessive heat is generated inside the battery or the internal pressure increases sharply due to thermal runaway of the electrode material and decomposition of the electrolyte, causing the battery to catch fire or explode.

[0005] To address battery safety concerns, the industry currently incorporates numerous current-cutoff devices into batteries to prevent fire or explosion. These designs present several issues: first, they occupy internal battery space, reducing the space available for active materials and lowering energy density. Second, these built-in current-cutoff devices are complex to design and must be compatible with the overall battery structure, resulting in high costs. Furthermore, each device must be developed separately for each battery model, leading to a lack of compatibility. Third, the activation requirements for these built-in current-cutoff devices require changes and adjustments to the battery's positive and negative electrode materials and electrolyte, preventing optimal battery performance. Summary of the Invention

[0006] In view of the above problems, the present invention proposes a connection device for a power battery to solve the safety problem when the battery system is abused such as overcharging.

[0007] The specific technical solutions are as follows:

[0008] A power battery connection device, which is an independent connection component used in series with the power battery, and the power battery circuit current passes through the inside of the connection device;

[0009] The connection device has a mechanism for cutting off the power battery circuit current;

[0010] The connecting device is connected to the gas pressure component inside the connecting device through the power battery voltage sampling component. When the power battery voltage becomes abnormal, the gas pressure inside the connecting device rises and actively disconnects the loop current of the power battery.

[0011] Optionally, the mechanism for cutting off the power battery circuit current is composed of a structural assembly including metal sheets and metal terminals at both ends. The structural assembly including the metal sheets is combined with the metal terminals at both ends. When the air pressure inside the cutting mechanism increases, the metal sheet will deform until it is disconnected from one of the metal terminals, but the disconnection form is not limited to this form.

[0012] Optionally, the metal terminals at both ends of the connecting device are connected in series with the power battery system. They can be connected in series inside the power battery system or outside the power system. The entire power system contains at least one or more of the connecting devices.

[0013] Optionally, components composed of corresponding arc-extinguishing media or arc-extinguishing materials are installed around the disconnection point of the disconnectable metal sheet, especially above it. The arc-extinguishing medium is such as sulfur hexafluoride (SF6), but is not limited to the listed substances; the arc-extinguishing material is such as quartz sand and ceramics, but is not limited to the listed substances.

[0014] Optionally, the gas pressure component inside the connecting device is an electrolytic cell, which includes a positive electrode, a negative electrode, an electrolyte solution and corresponding connecting terminals, and the connecting terminals are connected to the voltage sampling component of the power battery.

[0015] Optionally, the outer shell of the electrolytic cell is a shell with a certain compressive strength, the purpose of which is to limit the volume expansion of the electrolytic cell within a certain range.

[0016] Optionally, the starting voltage of the electrolytic cell for electrolysis is the battery voltage corresponding to an abnormal state of the power battery. The abnormal state includes but is not limited to battery overcharging. For example, the battery voltage of a lithium-ion battery when overcharging occurs is 4.2V or above.

[0017] Optionally, when the starting voltage for electrolysis is reached, the electrolytic cell will react or decompose to produce a large amount of gas, the gas components of which include one or more components such as carbon dioxide (CO2), methane (CH4), ethane (C2H6), hydrogen (H2), ethylene (C2H4), carbon monoxide (CO), acetylene (C2H2), etc., but are not limited to the gas components.

[0018] Alternatively, the gas generation method may be one of the following methods, such as decomposition of the electrolyte solution, decomposition of the positive electrode material, or decomposition of the negative electrode material, or a combination of the above methods. The selection and combination of the above multiple materials can also be used to flexibly adjust the starting voltage for electrolysis.

[0019] Optionally, the electrolyte solution is composed of two parts, one part is an electrolyte, the main components of which include but are not limited to lithium salts, sodium salts, potassium salts or other metal salts and various inorganic and organic compounds that can conduct electricity in the solution, such as lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium hexafluoroarsenate (LiAsF6), lithium perchlorate (LiClO4), lithium trifluoromethanesulfonate (LiCF3SO3), lithium bis(trifluoromethylsulfonyl)imide (LiN(SO2CF3)3), lithium tetrachloroaluminum (LiAlCl4), lithium hexafluorosilicate (LiSiF6), lithium tetraphenylborate (LiB(C6C5)4), lithium chloride (LiCl), lithium bromide (LiBr), lithium nitrate (LiNO3), sodium chloride (NaCl), sodium sulfate (Na2SO4), potassium chloride (KCl), potassium nitrate (KNO3) one or more composition; the other part is a non-aqueous solvent, such as propylene carbonate (PC), ethylene carbonate (EC), vinylene carbonate (VC), methyl ethyl carbonate (EMC), 1,2-dimethoxyethane, ethoxyethane, diethyl carbonate (DEC), dimethyl carbonate (DMC), tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, ethyl acetate, methyl propionate, methyl butyrate, can be used alone or in combination with one or more of these non-aqueous solvents, but are not limited to the above-mentioned non-aqueous solvents. At the same time, the electrolyte solution can be optionally added or not added with one or more additives that are prone to generate gas at the above-mentioned electrolysis starting voltage, such as cyclohexylbenzene (CHB) and biphenyl (BP), but are not limited to the above-mentioned compounds.

[0020] Optionally, the positive electrode of the electrolytic cell has a carrier that is a conductive metal or non-metallic substrate, and the substrate can also be coated with a certain active chemical substance. The material of the substrate is preferably aluminum, and can also be other metal or non-metallic materials that can conduct electricity but do not participate in the electrolysis reaction, such as titanium, platinum, gold, stainless steel, metal alloy, graphite; the active chemical substance can be a single substance or compound that can promote or catalyze the electrolysis reaction, such as carbon, silicon, aluminum oxide; the active chemical substance can also be a compound containing lithium or other alkali metals or alkaline earth metals, such as lithium carbonate (Li2CO3), lithium fluoride (LiF), lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium nickel cobalt manganese oxide (LiNixCoyMnzO2 (x+y+z=1)), ferrite Lithium (LiFeO2), lithium manganate (LiMn2O4), lithium ferrous phosphate (LiFePO4), lithium vanadate (Li1+xV3O8), lithium vanadium phosphate (Li3V2(PO4)3), lithium vanadium fluorophosphate (LiVPO4F), but not limited to the above compounds; the active chemical substance can also be an inorganic or organic compound that is more likely to react and produce gas under an applied voltage, such as calcium carbonate, sodium bicarbonate, ammonium nitrate, lithium carbonate, lithium oxalate, oxalic acid, maleic acid, sodium oxalate, sodium acetate, citric acid, lithium citrate, urea, maleic anhydride, but not limited to the above materials.

[0021] Optionally, the negative electrode of the electrolytic cell has a carrier that is a conductive metal or non-metallic matrix, and the carrier can be coated with certain chemical substances. The material of the carrier is preferably pure copper, but it can also be a metal or non-metallic material that is conductive but does not participate in the electrolysis reaction, such as nickel, steel, aluminum, other metal alloys, graphite, but not limited to the above components; the chemical substance is preferably a carbon material, and it can also be one or more combinations of silicon, lithium titanate, and tin, but not limited to the above components.

[0022] Optionally, the power battery voltage sampling component is two sampling terminals, which are respectively connected to the positive and negative electrodes of a battery in the power battery system;

[0023] The present invention also provides a battery system, characterized by comprising the connecting device.

[0024] The beneficial effects of the present invention are:

[0025] Through the above technical solution, by connecting at least one of these connection devices in series within a battery series circuit, overcharge protection can be easily implemented in single cells without a built-in current interrupter, without making any internal structural changes to the cells. This not only avoids a decrease in the energy density of the single cells, but also allows the connection device to be applied to a variety of different battery systems, avoiding the need to redesign the battery's internal structure, significantly improving compatibility and reducing costs. Furthermore, the voltage at which the connection device triggers a current interruption can be easily adjusted, avoiding changes to the complex internal electrochemical system of the battery, such as the matching of the positive and negative electrodes with the electrolyte, thereby ensuring optimal battery performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the structure of a battery system according to an embodiment of the present invention, wherein the connection device is connected in series in the battery circuit.

[0027] Figure 2 It is a side view of the connecting device of the present invention.

[0028] Figure 3 It is a cross-sectional view of the connecting device of the present invention.

[0029] Figure 4 It is a schematic diagram of the through-holes of the insulating component and the lower connecting piece of the metal sheet in the connecting device of the present invention.

[0030] Figure 5 It is a top view of the connecting device of the present invention.

[0031] Figure 6 It is a schematic diagram of the components of the electrolytic cell in the connecting device of the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical solution of the present invention clearer and more specific, the present invention is further described below with reference to the accompanying drawings. Any equivalent replacement of the technical features of the technical solution of the present invention and any solution derived by conventional reasoning shall fall within the scope of protection of the present invention.

[0033] Reference numerals

[0034] 1-Power battery system; 2-Power battery cell; 3-Connecting device; 31-Upper connecting plate; 32-Lower connecting plate; 33-Sampling line of power battery voltage sampling component; 34-Upper cover of connecting device; 35-Insulating component; 36-Lower connecting plate of metal sheet; 37-Connecting rivet of power battery voltage sampling component; 38-Electrolytic cell shell; 39-Electrolytic cell filling hole; 310-Metal sheet; 311-Metal sheet welding bracket; 312-Metal sheet welding base; 313-Electrolytic cell cavity; 314-Through hole; 315-Electrolytic cell; 3151-Positive electrode connection terminal of electrolytic cell; 3152-Upper diaphragm of electrolytic cell; 3153-Positive electrode of electrolytic cell; 3154-Negative electrode connection terminal of electrolytic cell; 3155-Lower diaphragm of electrolytic cell; 3156-Negative electrode of electrolytic cell; 4-Power battery cell.

[0035] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" are usually defined based on the drawing direction of the corresponding drawings, and "inside and outside" refer to the inside and outside of the corresponding component outline.

[0036] Figure 1 This is a structural diagram of a battery system according to an embodiment of the present invention, wherein the connecting device is connected in series in a battery circuit; and the power battery system contains at least one connecting device. Figure 2 It is a side view of the connecting device of the present invention. Figure 3 It is a cross-sectional view of the connecting device of the present invention. Figure 4 It is a schematic diagram of the insulating component and the lower through hole in the connecting device of the present invention. Figure 5 It is a top view of the connecting device of the present invention. Figure 6 It is a schematic diagram of the components of the electrolytic cell in the connecting device of the present invention.

[0037] In an embodiment of the present invention, the connecting device 3 of the present invention is connected in series in the power battery system 1, wherein the upper connecting piece 31 of the connecting device is connected to the negative pole of a power battery cell 2 in the power battery system, the lower connecting piece 32 of the connecting device is connected to the positive pole of the power battery cell 4, and the sampling line 33 of the power battery voltage sampling component is connected to the negative pole of another power battery cell 4 in the power battery system.

[0038] Specifically, if Figure 2 、 Figure 3 As shown, when the connection device 3 is in a normal state in the series circuit, the upper connecting piece 31 of the connection device is connected to the internal metal sheet 310 through the upper cover 34 of the connection device. The outer ring of the metal sheet 310 is welded to the metal sheet welding bracket 311, and the inner ring is welded to the metal sheet welding base 312. The metal sheet welding base 312 is connected to the metal sheet lower connecting piece 36, and an insulating component 35 is provided in the middle. The insulating component 35 has a through hole 314, as shown in FIG. Figure 3 and Figure 4Similarly, the metal sheet lower connecting piece 36 also has a through hole of the same size and location as the insulating component 35. This ensures that the electrolytic cell cavity 313 is connected to the bottom of the metal sheet, and the gas pressure therein is consistent. The electrolytic cell housing 38 is connected to the metal sheet lower connecting piece 36 and the connecting device lower connecting piece 32, respectively, to ensure normal current input and output, completing the charging and discharging operations of the battery system.

[0039] The electrolytic cell cavity 313 contains an electrolytic cell 315, which comprises a positive electrode connection terminal 3151, an upper diaphragm 3152, a positive electrode 3153, a negative electrode connection terminal 3154, a lower diaphragm 3155, and a negative electrode 3156. The positive electrode connection terminal 3151 is connected to a rivet 37 for the power battery voltage sampling component, while the negative electrode connection terminal 3154 is connected to the cell housing 38. The housing is provided with an electrolytic cell injection port 39; a certain amount of electrolyte is injected into the cell cavity 313 through this port.

[0040] The electrolyte consists of two parts. One part is a solvent, the main component of which is a lithium salt, such as one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium hexafluoroarsenate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium bis(trifluoromethylsulfonyl)imide, lithium tetrachloroaluminum, lithium hexafluorosilicate, lithium tetraphenylborate, lithium chloride, and lithium bromide; the other component is a non-aqueous solvent, such as propylene carbonate, ethylene carbonate, vinylene carbonate, 1,2-dimethoxyethane, ethoxyethane, diethyl carbonate, dimethyl carbonate, tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, 4-methyl-1,3-dioxolane, ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, methyl propionate, and methyl butyrate. One or more of these non-aqueous solvents can be used alone or in combination, and a variety of gas-generating additives, such as cyclohexylbenzene, can be used. In this embodiment, the lithium salt is lithium hexafluorophosphate with a concentration of 1 mol / L, the solvent system is a mixture of ethylene carbonate and ethyl methyl carbonate with a volume ratio of 3:7, and the additive is cyclohexylbenzene with a mass percentage of 5%.

[0041] The electrolytic cell positive electrode 3153 has a metal substrate as its carrier, which may be coated with a specific chemical substance. The metal substrate is preferably made of aluminum, but may also be other conductive metal materials that do not participate in the electrolysis reaction. The chemical substance is carbon or a lithium-containing chemical substance such as, but not limited to, lithium carbonate, lithium fluoride, lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, lithium metaferrite, lithium manganese oxide, lithium ferrous phosphate, lithium vanadate, lithium vanadium phosphate, and lithium vanadium fluoride phosphate. In this embodiment, the metal substrate is aluminum foil coated with a carbon material.

[0042] The electrolytic cell negative electrode 3156 has a metal substrate as its carrier, which may be coated with a chemical substance. The metal substrate is preferably made of pure copper, but may also be other metals such as nickel, steel, aluminum, or other metals or alloys, but are not limited to these compositions. The chemical substance is preferably a carbon material or other substances that react with lithium, and may also be one or more combinations of silicon, lithium titanate, and tin, but are not limited to these compositions. In an embodiment, the metal substrate is copper foil coated with a carbon material.

[0043] The positive electrode and the negative electrode of the electrolytic cell are insulated by the upper diaphragm 3152 and the lower diaphragm 3155 of the electrolytic cell, which are preferably conventional polyethylene or polypropylene porous diaphragms of lithium-ion batteries, but are not limited to the above-mentioned material diaphragms.

[0044] In this embodiment, the chemical system of the power battery system is: the positive electrode is lithium nickel cobalt manganese oxide, the negative electrode is graphite, and the electrolyte is a non-aqueous solvent dissolved with a certain concentration of lithium salt.

[0045] When the power battery is normally charged and discharged, the connecting device only plays a connecting role, and no reaction occurs in the electrolytic cell.

[0046] When the voltage of the power battery is abnormal, such as when the battery is overcharged, when the battery voltage is higher than 4.6V, the power battery voltage sampling component of the connection device connects the sampling 33 and the lower connecting piece 32 of the connection device to place the abnormal power battery voltage at both ends of the electrolytic cell positive electrode 3153 and the electrolytic cell negative electrode 3156 respectively. The electrolyte in the electrolytic cell cavity is rapidly oxidized and decomposed to produce gas under the influence of the positive and negative electrode voltages. Under the rapidly increasing gas pressure, the metal sheet 310 is disconnected from the metal sheet welding base 312, thereby cutting off the entire power battery system 1 circuit and stopping further charging of the power battery, thereby realizing the overcharge protection function.

[0047] When the metal sheet 310 is disconnected, the disconnected portion is in a high-voltage state. A corresponding arc-extinguishing medium or arc-extinguishing device is stored above the metal sheet 310. The arc-extinguishing medium is sulfur hexafluoride, which can avoid arcing due to high voltage, thereby improving the reliability of the system.

[0048] The electrolytic cell shell 38 is a 0.6 mm thick metal aluminum shell with a compressive strength of 800 kPa, which can ensure that the pressure in the electrolytic cell cavity starts normally without changes in the internal pressure of the cavity due to deformation of the shell.

[0049] As can be seen, the connection device of the present invention monitors the power battery voltage and implements an overcharge protection method by disconnecting the power battery circuit within the connection device. This effectively separates the power battery circuit disconnect device from the power battery itself, eliminating the need for complex structural design and electrolyte formulation adjustments to improve overcharge performance. In addition, because the connection device is external to the power battery, it can be replaced multiple times without disassembling the battery system, ensuring the maintainability of the battery system. Furthermore, the connection device can be used across different battery models without requiring a redesign for each model.

[0050] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0051] Furthermore, the present invention is not limited to lithium-ion batteries, but can also be applied to battery systems of other systems, the only difference being the substances in the electrolytic cells.

[0052] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner unless there is any contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. In addition, the various different embodiments of the present invention can also be combined in any manner, as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A connection device for a power battery system, characterized in that: The connecting device is an independent connecting component, which is used in series with the power battery, and the loop current of the power battery passes through the inside of the connecting device; The connection device has a mechanism for cutting off the current of the power battery circuit; The connection device is provided with an electrolytic cell inside, the electrolytic cell comprising a positive electrode, a negative electrode, an electrolyte solution and corresponding connection terminals, and the connection terminals are connected to the voltage sampling component of the power battery; The starting voltage of the electrolytic cell for electrolysis is the battery voltage corresponding to an abnormal state of the power battery. The abnormal state includes overcharging of the battery, and the electrolyte solution is rapidly oxidized and decomposed to produce gas under the influence of the positive and negative electrode voltages of the electrolytic cell, so that the gas pressure inside the connecting device increases and the loop current of the power battery is actively disconnected.

2. A connection device for a power battery system according to claim 1, characterized in that: The mechanism for cutting off the current of the power battery circuit is composed of a structural assembly including a metal sheet and metal terminals at both ends. The structural assembly including the metal sheet is combined with the metal terminals at both ends. When the air pressure inside the mechanism for cutting off the current of the power battery circuit increases, the metal sheet will deform until it is disconnected from one of the metal terminals.

3. A connection device for a power battery system according to claim 2, characterized in that: The metal terminals at both ends of the connecting device are connected in series with the power battery system. They are connected in series inside the power battery system or outside the power system. The entire power battery system contains at least one or more of the connecting devices.

4. A connection device for a power battery system according to claim 2, characterized in that: Components composed of corresponding arc-extinguishing medium or arc-extinguishing material are installed around the disconnection point of the disconnectable metal sheet; the arc-extinguishing medium is sulfur hexafluoride; the arc-extinguishing material is quartz sand or ceramics.

5. The connection device of a power battery system according to claim 1, characterized in that: The outer shell of the electrolytic cell is a shell with compressive strength, the purpose of which is to limit the volume expansion of the electrolytic cell within a certain range.

6. The connection device of a power battery system according to claim 1, characterized in that: When the starting voltage for electrolysis is reached, a large amount of gas will be produced by reaction or decomposition in the electrolytic cell, and its gas components include one or more of carbon dioxide, methane, ethane, hydrogen, ethylene, carbon monoxide or acetylene.

7. A connection device for a power battery system according to claim 6, characterized in that: The gas generation method is one of (1) decomposition of electrolyte solution, (2) decomposition of positive electrode material, (3) decomposition of negative electrode material, or a combination of multiple methods. The selection and combination of the above multiple materials can also be used to flexibly adjust the starting voltage for electrolysis.

8. The connection device of a power battery system according to claim 1, characterized in that: The electrolyte solution is composed of two parts, one part is the electrolyte, whose main components include lithium salts, sodium salts, potassium salts or other metal salts and various inorganic compounds or organic compounds that conduct electricity in the solution; the other part is a non-aqueous solvent; at the same time, one or more additives that are prone to generate gas at the starting voltage of electrolysis are added or not added to the electrolyte solution.

9. The connection device of a power battery system according to claim 1, characterized in that: The positive electrode of the electrolytic cell has a carrier that is a conductive metal or non-metallic matrix, and the carrier is also coated with active chemical substances; the active chemical substances are single substances or compounds that can promote or catalyze electrolytic reactions, compounds containing lithium or other alkali metals or alkaline earth metals, and inorganic or organic compounds that are more likely to react and produce gas under an applied voltage.

10. The connection device of a power battery system according to claim 1, characterized in that: The negative electrode of the electrolytic cell has a carrier that is a conductive metal or non-metallic matrix, and the carrier is coated with a chemical substance; the chemical substance is one or a combination of carbon, silicon, lithium titanate or tin.

11. A connection device for a power battery system according to claim 1, characterized in that: The power battery voltage sampling component consists of two sampling terminals, which are respectively connected to the positive and negative poles of a battery in the power battery system.

12. A battery system, characterized in that: A connecting device comprising any one of claims 1 to 11.

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