Internal short circuit simulation device for lithium ion battery and use method thereof

Abstract

The present invention provides a lithium-ion battery internal short circuit simulation device, comprising a lithium-ion battery and a first wire, a high-voltage power supply, a third wire, a switch, and a second wire electrically connected in sequence; the first wire and the second wire entering the pole core are closely attached to two different surfaces of the same diaphragm, and the insulating shells of the two are provided with a plurality of openings facing the diaphragm side. The present invention also provides a method for using the device, assembling the device with the switch kept disconnected, and then charging the lithium-ion battery to the charge state specified in the experiment, briefly closing the switch to allow the cores of the first wire and the second wire to discharge at high voltage through the opening position and form an electric spark, break through the diaphragm to form a direct conduction between the positive electrode sheet and the negative electrode sheet, thereby realizing the battery internal short circuit simulation experiment. The device has a simple structure, is easy to prepare, and is low in cost. It has little effect on the structure and performance of the battery itself, is simple and easy to use, and is controllable in operation. The internal short circuit position and range can be flexibly set.

Description

Technical Field

[0001] The present invention relates to the field of lithium ion batteries, and in particular to an internal short circuit simulation device for lithium ion batteries and a use method thereof. Background Art

[0002] Lithium-ion batteries are widely used in various sectors of the national economy and in the areas of residents' lives. As chemical energy storage devices with high energy density and activity, lithium-ion batteries inevitably have safety issues, among which the most prominent safety issue is the internal short circuit of lithium-ion batteries. Due to various factors such as defects in the materials and manufacturing processes of lithium-ion batteries themselves and external abuse, in some cases, some areas of the positive and negative electrodes inside the lithium-ion battery will lose the isolation effect of the diaphragm and contact each other, which will cause an internal short circuit in the battery, resulting in adverse consequences such as temperature rise and even fire and explosion.

[0003] In order to avoid various negative problems caused by internal short circuits and reduce their harm, as summarized in Chinese patent CN105633489B, it is very necessary to carry out internal short circuit simulation tests of lithium-ion soft-pack batteries in an artificially controllable manner through experimental means, so as to evaluate the degree of harm of internal short circuits and optimize relevant design parameters and manufacturing processes; in addition, the internal short circuit simulation test technology of lithium-ion batteries can also help people design and improve various internal short circuit monitoring, diagnosis and alarm methods. However, there are three problems in the various currently known internal short circuit simulation test technologies for lithium-ion batteries: first, the structure is complex and the sample preparation is troublesome; second, the internal short circuit device and its triggering conditions have additional effects on the battery's own structure and performance; third, the stability, controllability and repeatability are not high. Therefore, it is urgent to propose a new internal short circuit simulation device and its use method for lithium-ion batteries. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a lithium ion battery internal short circuit simulation device and a use method thereof which has a simple structure, is easy to prepare, has a low cost, is controllable in operation, and has little impact on the battery itself.

[0005] According to one aspect of the present invention, a short circuit simulation device for a lithium-ion battery is provided, comprising a lithium-ion battery, a high-voltage power supply, a switch and a conductor; the lithium-ion battery is provided with a shell and a pole core located inside the shell, the pole core is provided with a plurality of positive pole sheets, a plurality of negative pole sheets and a diaphragm located between adjacent positive pole sheets and negative pole sheets and used to isolate the adjacent positive pole sheets and negative pole sheets; the high-voltage power supply and the switch are located outside the lithium-ion battery; the conductor comprises a first conductor, a second conductor and a third conductor, the first conductor, the high-voltage power supply, the third conductor, the switch and the second conductor are electrically connected in sequence; one end of the first conductor is electrically connected to the high-voltage power supply, and the other end thereof passes through the shell of the lithium-ion battery into the pole core and is closely attached to the surface of the diaphragm; one end of the second conductor is electrically connected to the switch, and the other end thereof passes through the lithium-ion battery The shell enters the pole core and is tightly attached to the surface of the diaphragm; the parts of the first wire and the second wire entering the pole core are tightly attached to two different surfaces of the same diaphragm, and the shapes and placement positions of the two are symmetrical relative to the diaphragm they are tightly attached to; the first wire and the second wire are both composed of a wire core and an insulating shell layer for wrapping the wire core; the insulating shell layer of the first wire and the second wire tightly attached to the surface of the diaphragm is provided with a plurality of openings facing the diaphragm side, the number of openings on the first wire and the second wire is equal, any opening on the first wire forms a one-to-one correspondence with a certain opening on the second wire, the corresponding same pair of openings have the same shape and size, and the two are symmetrical relative to the diaphragm they are tightly attached to; the shapes and placement positions of the openings on the insulating shell layers of the first wire and the second wire are symmetrical relative to the diaphragm they are tightly attached to.

[0006] In the above-mentioned lithium-ion battery internal short-circuit simulation device, the first conductive wire and the second conductive wire are both flat conductive wires, and the openings of the insulating shell layer on the same conductive wire are both located on the side of the conductive wire close to the diaphragm.

[0007] In the above-mentioned lithium-ion battery internal short-circuit simulation device, the voltage value of the high-voltage power supply is between 1 and 50 times the breakdown voltage of the diaphragm.

[0008] Preferably, the insulating shells of the first wire and the second wire are both made of polytetrafluoroethylene material resistant to electrolyte corrosion.

[0009] Preferably, the cores of the first conductive wire and the second conductive wire are made of any one of the following four materials: aluminum, copper, aluminum alloy, and copper alloy.

[0010] According to another aspect of the present invention, a method for using the above-mentioned lithium-ion battery internal short-circuit simulation device is provided. The device is assembled with a switch kept in an open state, and after the lithium-ion battery is charged to a charge state specified in the experiment, the switch is briefly closed to allow the cores of the first wire and the second wire to discharge at high voltage through the opening position and form an electric spark, thereby breaking through the diaphragm to form direct conduction between the positive electrode sheet and the negative electrode sheet.

[0011] The beneficial effects of the present invention are:

[0012] 1. The present invention makes full use of the principle that two conductors that are not in direct contact with each other will generate a high-voltage arc and break through the medium between them when there is a very high voltage difference. By arranging two wires on both sides of the diaphragm in advance and stripping the local insulation layer of the wires to form a number of opening pairs, a high voltage is applied between the two wires, and a high-voltage arc is released between the opening pairs to break through the local diaphragm near it, forming a local diaphragm opening, and causing direct conduction between the local positive and negative electrodes to achieve the purpose of internal short circuit. The device of the present invention only needs to send two wires into the battery, and the wires can be made into a flat shape. The insulating shell and the wire core can be made of polytetrafluoroethylene and copper-aluminum metals that are resistant to electrolyte corrosion and often exist in the battery itself, and the insulating shell and the battery shell can also be conveniently sealed by hot melting and other methods. Therefore, the device is simple and convenient to manufacture and assemble, does not affect the battery's own structure and the original process and test process, does not introduce new substances, does not pollute the internal chemical composition of the battery, and has little effect on the battery performance.

[0013] 2. In the method of using the device of the present invention, a high-voltage arc is generated by instantaneous discharge to break through a local diaphragm. This method can suddenly form an internal short circuit in the battery in a very short time, with little effect on battery performance and normal test procedures, good controllability and repeatability, and can flexibly arrange the wire direction and the shape, size, number and position of the openings according to the needs of the simulation experiment to achieve precise control of the position and range of the internal short circuit.

[0014] 3. The simulation device and method of use of the present invention can easily induce short circuits in any one or more battery cells in a battery module in a specified time sequence, and can well simulate the internal short circuit failure and its spread of battery cells in the module. In the known technical solutions, acupuncture is usually used to induce internal short circuits. Due to the blocking effect of the batteries in the module, this acupuncture method is difficult to bypass adjacent batteries and induce internal short circuits in a specific battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 1 is a schematic diagram of the structure of a lithium-ion battery in an embodiment of the present invention, in which 1 is a shell; 2 is a pole, wherein 21 is a positive pole, and 22 is a negative pole; 3 is a pole core; 4 is a pole ear, wherein 41 is a positive pole ear, and 42 is a negative pole ear.

[0016] Figure 2 1 is a schematic diagram of the structure of a short-circuit simulation device for a lithium-ion battery in an embodiment of the present invention, in which 1 is a shell, 3 is a pole core, 22 is a negative pole column, 42 is a negative pole ear, 51, 52, 53 are respectively a first wire, a second wire, and a third wire, 6 is a high-voltage power supply, and 7 is a switch.

[0017] Figure 3 for Figure 2 A partial enlarged view of the dotted frame portion, in which 31 is the positive electrode sheet, 51 and 52 are the first wire and the second wire respectively, 32 is the separator, and 33 is the negative electrode sheet; 511 is the core of the first wire 51, 512 is the insulating shell of the first wire 51, and 513 is the opening of the first wire 51; 521 is the core of the second wire 52, 522 is the insulating shell of the second wire 52, and 523 is the opening of the second wire 52. DETAILED DESCRIPTION

[0018] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] like Figures 1 to 3 As shown, a short circuit simulation device for a lithium-ion battery comprises a lithium-ion battery, a high-voltage power supply, a switch and a wire; the lithium-ion battery is provided with a shell and a pole core located inside the shell, the pole core is provided with a plurality of positive plates, a plurality of negative plates and a diaphragm located between adjacent positive plates and negative plates and used to isolate the adjacent positive plates and negative plates; the high-voltage power supply and the switch are located outside the lithium-ion battery; the wire comprises a first wire, a second wire and a third wire, the first wire, the high-voltage power supply, the third wire, the switch and the second wire are electrically connected in sequence; one end of the first wire is electrically connected to the high-voltage power supply, and the other end thereof passes through the shell of the lithium-ion battery to enter the pole core and is closely attached to the surface of the diaphragm; one end of the second wire is electrically connected to the switch, and the other end thereof passes through the shell of the lithium-ion battery to enter The first conductor and the second conductor have a core and are in close contact with the surface of the diaphragm; the parts of the first conductor and the second conductor entering the core are in close contact with two different surfaces of the same diaphragm, and the shapes and placement positions of the two are symmetrical relative to the diaphragm they are in close contact with; the first conductor and the second conductor are both composed of a core and an insulating shell for wrapping the core; the insulating shell of the first conductor and the second conductor in close contact with the surface of the diaphragm is provided with a plurality of openings facing the diaphragm side, the number of openings on the first conductor and the second conductor is equal, any opening on the first conductor forms a one-to-one correspondence with a certain opening on the second conductor, the shapes and sizes of the corresponding openings of the same pair are the same, and the two are symmetrical relative to the diaphragm they are in close contact with; the shapes and placement positions of the openings on the insulating shells of the first conductor and the second conductor are symmetrical relative to the diaphragm they are in close contact with.

[0020] In the above-mentioned lithium-ion battery internal short-circuit simulation device, the first conductive wire and the second conductive wire are both flat conductive wires, and the openings of the insulating shell layer on the same conductive wire are both located on the side of the conductive wire close to the diaphragm.

[0021] In the above-mentioned lithium-ion battery internal short-circuit simulation device, the voltage value of the high-voltage power supply is between 1 and 50 times the breakdown voltage of the diaphragm.

[0022] The method for using the above-mentioned lithium-ion battery internal short-circuit simulation device is to assemble the device with the switch kept in the disconnected state, and then after the lithium-ion battery is charged to the charge state specified in the experiment, the switch is briefly closed to allow the cores of the first wire and the second wire to discharge at high voltage through the opening position and form an electric spark, which breaks through the diaphragm to form direct conduction between the positive electrode sheet and the negative electrode sheet.

[0023] Example

[0024] A laminated plastic shell square lithium-ion battery, Figure 1 The schematic diagram of the structure is given from a top view, and the interior of the battery housing 1 includes a positive electrode ear, which is a positive electrode ear 41; a negative electrode ear, which is a negative electrode ear 42; a positive electrode column, which is a positive electrode column 21; and a negative electrode column, which is a negative electrode column 22. The positive electrode ear 41 is electrically connected to the positive electrode column 21, and the negative electrode ear 42 is electrically connected to the negative electrode column 22. The positive electrode ear 41, the positive electrode column 21, the negative electrode ear 42 and the negative electrode column 22 are all insulated from the housing 1.

[0025] like Figure 2 As shown, assemble the internal short circuit simulation device, Figure 2 The middle battery is drawn in the main view direction, so the positive electrode ear 41 is blocked by the negative electrode ear 42, and only the negative electrode ear 42 is drawn; the positive electrode column 21 is blocked by the negative electrode column 22, and only the negative electrode column 22 is drawn. The first wire 51 and the second wire 52 both pass through the shell 1 and enter the inside of the pole core 3 to perform an internal short circuit simulation experiment at a certain diaphragm layer. The contact position between the first wire 51, the second wire 52 and the shell 1 is sealed by hot melting.

[0026] Figure 2 The enlarged part within the dotted line frame is shown in Figure 3 , Figure 3 For the convenience of observation, the exploded view shows a larger distance between the various structural parts, but in fact, the adjacent structures of each part are in close contact. Figure 3 From top to bottom, there are the positive electrode sheet 31, the first wire 51, the separator 32, the second wire 52 and the negative electrode sheet 33. Taking the first wire 51 as an example, two local openings 513 are provided on the insulating shell 512 close to the separator 32, and the second wire 52 is similar. Finally, the two openings 513 on the first wire 51 and the two openings 523 on the second wire 52 are symmetrical with respect to the separator 32, forming two opening pairs located on the left and right sides respectively.

[0027] In this embodiment, the lithium-ion battery is fully charged at room temperature of the diaphragm 32 and then left for 1 hour, and the voltage value of the high-voltage power supply 6 is selected to be 2000 V. In the internal short circuit simulation experiment, the switch 7 is briefly closed for 20 milliseconds, so that the two diaphragms directly below the opening 513 are punctured by the high-voltage arc, and the positive electrode sheet 31 and the negative electrode sheet 33 at this position are directly connected due to the loss of the isolation effect of the diaphragm 32, thereby causing an internal short circuit.

[0028] It should be pointed out that, in addition to the lithium-ion battery, the device of the embodiment only includes the same set of electrical modules consisting of a single number of first wires 51, second wires 52, third wires 53, high-voltage power supply 6 and switch 7. In fact, according to the needs of the internal short-circuit simulation experiment, multiple sets of independent electrical modules can be set for the same lithium-ion battery, and the diaphragm positions, directions and lengths of the first wires 51 and second wires 52 of each set of electrical modules can be different, and the voltage value of the high-voltage power supply 6 and the closing time and closing duration of the switch 7 can also be different, so that the diaphragms at different positions of the lithium-ion battery or even multiple positions of the same diaphragm can be conveniently made to realize internal short-circuit events of different degrees in chronological order.

[0029] This embodiment makes full use of the principle that two conductors that are not in direct contact with each other will generate a high-voltage arc and break through the medium between them when there is a very high voltage difference. By arranging two wires on both sides of the diaphragm in advance and stripping the local insulation layer of the wires to form a number of opening pairs, a high voltage is applied between the two wires, and a high-voltage arc is released between the opening pairs to break through the local diaphragm near it, forming a local diaphragm opening, and causing the local positive and negative electrodes to be directly connected to achieve the purpose of internal short circuit. The device of this embodiment only needs to send two wires into the battery, and the wires can be made into a flat shape. The insulating shell and the wire core can be made of polytetrafluoroethylene and copper metal that are resistant to electrolyte corrosion and often exist in the battery itself, and the insulating shell and the battery shell are also sealed by hot melting and other methods. Therefore, the device is simple and convenient to manufacture and assemble, does not affect the battery's own structure and the original process and test process, does not introduce new substances, does not pollute the internal chemical composition of the battery, and has little effect on the battery performance. In this embodiment, a high-voltage arc is produced by instantaneous discharge to penetrate a local diaphragm. This method can suddenly form an internal short circuit in the battery in a very short period of time, with little effect on battery performance and normal test procedures. It has good controllability and repeatability, and can flexibly arrange the wire direction and the shape, size, number and position of the openings according to the needs of the simulation experiment to achieve precise control of the position and range of the internal short circuit.

Claims

1. A lithium-ion battery internal short circuit simulation device, characterized in that: The invention comprises a lithium-ion battery, a high-voltage power supply, a switch and a wire; the lithium-ion battery is provided with a shell and a pole core located inside the shell, the pole core is provided with a plurality of positive plates, a plurality of negative plates and a diaphragm located between adjacent positive plates and negative plates and used to isolate the adjacent positive plates and negative plates; the high-voltage power supply and the switch are located outside the lithium-ion battery; the wire comprises a first wire, a second wire and a third wire, the first wire, the high-voltage power supply, the third wire, the switch and the second wire are electrically connected in sequence; one end of the first wire is electrically connected to the high-voltage power supply, and the other end thereof passes through the shell of the lithium-ion battery to enter the pole core and is closely attached to the surface of the diaphragm; one end of the second wire is electrically connected to the switch, and the other end thereof passes through the shell of the lithium-ion battery to enter the pole core and is closely attached to the surface of the diaphragm surface; the parts of the first wire and the second wire entering the pole core are closely attached to two different surfaces of the same diaphragm, and the shapes and placement positions of the two are symmetrical relative to the diaphragm they are closely attached to; the first wire and the second wire are both composed of a wire core and an insulating shell for wrapping the wire core; the insulating shell of the first wire and the second wire closely attached to the surface of the diaphragm is provided with a plurality of openings facing the diaphragm side, the number of openings on the first wire and the second wire is equal, any opening on the first wire forms a one-to-one correspondence with a certain opening on the second wire, the shapes and sizes of the corresponding same pair of openings are the same and the two are symmetrical relative to the diaphragm they are closely attached to; the shapes and placement positions of the openings on the insulating shells of the first wire and the second wire are symmetrical relative to the diaphragm they are closely attached to.

2. The lithium-ion battery internal short-circuit simulation device according to claim 1, characterized in that: The first conductive wire and the second conductive wire are both flat conductive wires, and the openings of the insulating shell on the same conductive wire are both located on the side of the conductive wire close to the diaphragm.

3. The lithium-ion battery internal short-circuit simulation device according to claim 1, characterized in that: The voltage value of the high voltage power supply is between 1 and 50 times the breakdown voltage of the diaphragm.

4. A method for using the lithium-ion battery internal short-circuit simulation device according to any one of claims 1 to 3, characterized in that: The device is assembled with the switch kept open, and after the lithium-ion battery is charged to the charge state specified in the experiment, the switch is briefly closed to allow the cores of the first wire and the second wire to discharge at high voltage through the opening position and form an electric spark, which breaks through the diaphragm to form direct conduction between the positive electrode plate and the negative electrode plate.

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