System and method for measuring internal temperature of lithium ion battery

Abstract

The invention relates to the technical field of batteries, in particular to an internal temperature measuring system and method of a lithium ion battery, and aims to solve the technical problems of how to realize multi-point measurement of the internal temperature of the lithium ion battery and how to reduce the influence on the lithium ion battery. In order to achieve the purpose, the internal temperature measuring system of the lithium ion battery comprises a thin film sensor arranged in the lithium ion battery, and the thin film sensor comprises a plurality of measuring points; the resistance acquisition device is used for being connected with a plurality of measuring points of a thin film sensor of the lithium ion battery and acquiring the resistance of the measuring points; and the detection unit is used for acquiring the temperature of each measurement point according to the resistance of each measurement point and the calibration curve of the measurement point so as to detect a plurality of temperatures in the lithium ion battery, so that more comprehensive temperature detection in the lithium ion battery is realized, a failure mechanism is convenient to analyze, and a basis is provided for improving the safety of the lithium ion battery.

Description

Technical Field

[0001] The present application relates to the field of battery technology, and in particular to a system and method for measuring the internal temperature of a lithium-ion battery. Background Art

[0002] Lithium-ion batteries have the advantages of high energy density and long cycle life. They are considered to be the best energy storage device for storing renewable energy and have been widely used in portable electronic devices, electric vehicles, and hybrid vehicles. However, explosions and spontaneous combustion occur frequently in many applications. Therefore, thermal safety has become a key issue in LIBs (Lithium-Ion Battery). Self-temperature rise can lead to performance degradation of lithium-ion batteries, and even spontaneous combustion and explosion during charging and discharging. Therefore, temperature monitoring is of great significance to ensure the safe operation of LIBs. Due to heat conduction, there is a significant difference between the external and internal temperatures of LIBs, especially in overcharging / discharging at high current rates or under extreme conditions. Using external temperature measurement, there is a risk if the actual temperature in the LIB is underestimated. Therefore, the internal temperature measurement of LIBs is very important. Considering the safe operating temperature range of practical applications, the single-point internal temperature measurement method is obviously not enough to meet the requirements, and the development of multi-point temperature measurement methods is an urgent need. However, when measuring the internal temperature of lithium-ion batteries, the inserted sensor will inevitably affect the performance of lithium-ion batteries.

[0003] Therefore, how to achieve multi-point measurement of the internal temperature of a lithium-ion battery and reduce the impact on the lithium-ion battery is an important issue that needs to be solved in the art. Summary of the invention

[0004] In order to overcome the above-mentioned defects, the present application is proposed to solve or at least partially solve the technical problem of how to achieve multi-point measurement of the internal temperature of a lithium-ion battery and reduce the impact on the lithium-ion battery.

[0005] In a first aspect, a system for measuring the internal temperature of a lithium-ion battery is provided, comprising:

[0006] A thin film sensor for being arranged inside the lithium ion battery, the thin film sensor comprising a plurality of measuring points;

[0007] a resistance acquisition device, configured to be connected to a plurality of measurement points of the thin film sensor and acquire the resistance of each measurement point;

[0008] The detection unit is configured to obtain the temperature of each measurement point according to the resistance of each measurement point and the calibration curve of the measurement point, so as to detect multiple temperatures inside the lithium-ion battery.

[0009] In a technical solution of the internal temperature measurement system of the above-mentioned lithium-ion battery, when the thin film sensor is arranged inside the lithium-ion battery, the thin film sensor is attached to a preset area on the electrode of the lithium-ion battery where the active material is removed; the electrode is a positive electrode sheet or a negative electrode sheet.

[0010] In a technical solution of the internal temperature measurement system of the lithium-ion battery, the thin film sensor includes a stacked substrate and a covering layer, and the multiple measurement points are arranged on a side of the substrate away from the pole piece.

[0011] In a technical solution of the internal temperature measurement system of the lithium-ion battery, the substrate and the cover layer are both polyimide sheets.

[0012] In a technical solution of the internal temperature measurement system of the lithium-ion battery, the measurement points are platinum measurement points deposited on the substrate by magnetron sputtering.

[0013] In a technical solution of the internal temperature measurement system of the lithium-ion battery, the width of the preset area is greater than the width of the thin film sensor;

[0014] The thickness of the preset area is greater than the thickness of the thin film sensor; and / or the thickness of the thin film sensor is less than 50 μm.

[0015] In a technical solution of the internal temperature measurement system of the lithium-ion battery, the calibration curve is a curve generated before the thin film sensor is attached to the positive electrode sheet, representing the corresponding relationship between the resistance of each measurement point and the ambient temperature.

[0016] In a second aspect, a method for measuring the internal temperature of a lithium ion battery is provided, the method comprising:

[0017] A thin film sensor is arranged inside the lithium ion battery to be tested, wherein the thin film sensor includes a plurality of measuring points;

[0018] Connecting multiple measuring points of the thin film sensor of the lithium ion battery to a resistance acquisition device, and obtaining the resistance of each measuring point;

[0019] The temperature of each measuring point is obtained according to the resistance of each measuring point and the calibration curve of the measuring point, so as to detect multiple temperatures inside the lithium-ion battery.

[0020] In one technical solution of the above-mentioned method for measuring the internal temperature of a lithium ion battery, the lithium ion battery is prepared according to the following steps:

[0021] Removing active material from a preset area on the electrode;

[0022] Attaching a thin film sensor to a preset area where the active material is removed; wherein the thin film sensor includes a plurality of measuring points;

[0023] A lithium-ion battery is prepared using the pole piece with the thin film sensor attached thereto; wherein the multiple measurement points are used to detect the internal temperature of the lithium-ion battery.

[0024] In a technical solution of the above-mentioned method for measuring the internal temperature of a lithium-ion battery, the method further comprises:

[0025] Before the thin film sensor is arranged inside the lithium-ion battery, obtaining a corresponding relationship between the resistance of each measuring point of the thin film sensor and the ambient temperature;

[0026] According to the corresponding relationship, a calibration curve of each measuring point is obtained.

[0027] The above one or more technical solutions of the present application have at least one or more of the following beneficial effects:

[0028] In the implementation of the lithium-ion battery technical solution provided by the present application, the internal temperature measurement system of the lithium-ion battery of the present application includes a thin film sensor for being arranged inside the lithium-ion battery, and the thin film sensor includes multiple measurement points; a resistance acquisition device is used to connect with the multiple measurement points of the thin film sensor of the lithium-ion battery and obtain the resistance of the measurement points; a detection unit is used to obtain the temperature of the measurement point according to the resistance of each measurement point and the calibration curve of the measurement point, so as to detect multiple temperatures inside the lithium-ion battery. Through the above configuration, the present application integrates the thin film sensor into the lithium-ion battery, and the thin film sensor includes multiple measurement points, which can realize more comprehensive temperature detection inside the lithium-ion battery, and can more comprehensively understand the internal temperature of the lithium-ion battery, which provides a basis for analyzing the failure mechanism of the lithium-ion battery and improving the safety of the lithium-ion battery.

[0029] Furthermore, by integrating thin film sensors on the pole pieces of lithium-ion batteries, the principle of ion flow between positive and negative electrodes can be effectively used to display the changes in the internal temperature of lithium-ion batteries at different current rates in real time. Moreover, long-term cycle experiments have shown that attaching thin film sensors to the pole pieces of lithium-ion batteries has limited impact on the performance of lithium-ion batteries, and can achieve multi-point measurement of the internal temperature of lithium-ion batteries with minimal impact on the performance of lithium-ion batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The disclosure of the present application will become easier to understand with reference to the accompanying drawings. It is easy for those skilled in the art to understand that these drawings are only for illustrative purposes and are not intended to limit the scope of protection of the present application. Among them:

[0031] Figure 1is a structural block diagram of the main components of a system for measuring the internal temperature of a lithium-ion battery according to an embodiment of the present application;

[0032] Figure 2 It is a schematic diagram of the main process of attaching a thin film sensor on a positive electrode sheet of a lithium ion battery according to one implementation of an embodiment of the present application;

[0033] Figure 3 It is a schematic flow chart of main steps of a method for measuring the internal temperature of a lithium-ion battery according to an embodiment of the present application;

[0034] Figure 4 It is a schematic flow chart of the main steps of a method for preparing a lithium-ion battery according to an embodiment of the present application.

[0035] Reference numerals:

[0036] 11: resistance acquisition device; 12: detection unit. DETAILED DESCRIPTION

[0037] Some embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the protection scope of the present application.

[0038] In the description of the present application, "module" and "processor" may include hardware, software or a combination of the two. A module may include hardware circuits, various suitable sensors, communication ports, memory, and may also include software parts, such as program code, or a combination of software and hardware. The processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor or any other suitable processor. The processor has data and / or signal processing functions. The processor may be implemented in software, hardware or a combination of the two. Computer-readable storage media include any suitable medium that can store program code, such as a disk, a hard disk, an optical disk, a flash memory, a read-only memory, a random access memory, etc. The term "A and / or B" means all possible combinations of A and B, such as only A, only B or A and B. The term "at least one A or B" or "at least one of A and B" has a similar meaning to "A and / or B" and may include only A, only B or A and B. The singular terms "one" and "the" may also include plural forms.

[0039] See attached Figure 1 , Figure 1 FIG. 1 is a block diagram of the main components of a lithium-ion battery internal temperature measurement system according to an embodiment of the present application. Figure 1As shown, the internal temperature measurement system of the lithium-ion battery of the embodiment of the present application mainly includes a thin film sensor, a resistance acquisition device 11 and a detection unit 12. In this embodiment, the thin film sensor is used to be arranged inside the lithium-ion battery, and the thin film sensor includes multiple measurement points. The resistance acquisition device 11 can be configured to be connected to multiple measurement points of the thin film sensor of the lithium-ion battery and obtain the resistance of each measurement point. The detection unit 12 can be configured to obtain the temperature of the measurement point according to the resistance of each measurement point and the calibration curve of the measurement point, so as to detect multiple temperatures inside the lithium-ion battery.

[0040] In one embodiment, when the thin film sensor is disposed inside a lithium-ion battery, the thin film sensor is attached to a preset area on a pole piece of the lithium-ion battery from which active substances are removed. The pole piece includes a positive electrode piece or a negative electrode piece. Removing the active substances can prevent the preset area to which the thin film sensor is attached from participating in the charge and discharge chemical reaction. At the same time, since the temperature change of the pole piece is more obvious during the charge and discharge process of the lithium-ion battery, attaching the thin film sensor to the pole piece can better reflect the internal temperature change of the lithium-ion battery.

[0041] In one embodiment, since the temperature change of the positive electrode sheet is more obvious than that of the negative electrode sheet during the charge and discharge process of the lithium-ion battery, the thin film sensor can be arranged in a preset area of ​​the positive electrode sheet where the active material is removed.

[0042] In one embodiment, the active substance may be removed by a solvent, and the solvent may be N-methylpyrrolidone solvent (NMP).

[0043] In one embodiment, the width of the preset area is greater than the width of the thin film sensor; the thickness of the preset area is greater than the thickness of the thin film sensor.

[0044] In one embodiment, the thin film sensor may include a stacked substrate and a cover layer, and a plurality of measurement points may be set on a side of the substrate away from the electrode. The sensor in the thin film sensor may be a resistance temperature detector (RTD), whose resistance increases with increasing temperature, and the temperature condition may be obtained by measuring the resistance. Among them, the small size of the thin film of the thin film sensor can provide a faster response and achieve compatibility with the lithium-ion battery assembly process.

[0045] In one embodiment, the substrate and the cover layer of the thin film sensor may both be polyimide sheets.

[0046] In one embodiment, the measuring point may be a platinum measuring point deposited on the substrate by magnetron sputtering.

[0047] In a specific example, the thickness of the polyimide sheet is 20μm. The polyimide sheet is used as the substrate and cover layer of the thin film sensor. The polyimide sheet has the advantages of electrical insulation, good chemical and temperature stability, etc. At the same time, the polyimide sheet has no effect on the sensitivity and thermal response of the thin film sensor. Using magnetron sputtering, platinum is deposited on the substrate to form seven measurement points. The size of each measurement point is 5mm×5mm, and the distance between two measurement points is 5mm. The thickness of the thin film sensor is less than 50μm.

[0048] In one embodiment, a positive electrode sheet and a diaphragm of the same size can be used to manufacture an ordinary lithium-ion battery without an integrated thin film sensor, and a lithium-ion battery with an integrated thin film sensor and an ordinary lithium-ion battery without an integrated thin film sensor are compared and tested to determine whether the placement of the thin film sensor has an impact on the lithium-ion battery. The EIS (Electrochemical Impedance Spectroscopy) method can be used for comparative testing. The test shows that there is no significant difference in the electrochemical properties of lithium-ion batteries with integrated thin film sensors and ordinary lithium-ion batteries. At the same time, experiments show that lithium-ion batteries with integrated thin film sensors have stable discharge capacity and coulomb efficiency, and lithium-ion batteries with integrated thin film sensors have stable electrochemical properties under long-term testing. Among them, EIS is a method for studying the electrode system by using a small-amplitude sinusoidal potential (or current) as a disturbance signal to produce an approximately linear response of the electrode system, and measuring the impedance spectrum of the electrode system over a wide frequency range.

[0049] In one embodiment, each measurement point of the thin film sensor has a corresponding calibration curve, and the calibration curve represents the corresponding relationship between the measured resistance and the ambient temperature. The calibration curve can be measured before the thin film sensor is attached to the positive electrode sheet. The specific measurement method is:

[0050] The thin film sensor is placed in an environmental chamber, where the operating temperature range is 20 to 90°C. The resistance of each measurement point is obtained using a multi-channel resistance acquisition system, and the resistance is recorded every 5°C using a four-wire connection method. Finally, the resistance of each measurement point at each ambient temperature is used to generate a calibration curve for each measurement point. Among them, the four-wire connection method is a method in which the voltage loop and the current loop are separated from each other, two wires are used to measure the voltage across the resistor, and the other two wires are used to measure the resistance value of the excitation source current loop. The four-wire connection method can obtain more accurate measurement results.

[0051] Experiments show that thin-film sensors can measure the internal temperature changes of lithium-ion batteries at different current rates in real time, and their temperature distribution is almost uniform. In the experiment, the internal temperature of the battery measured at the first cycle and the 100th cycle was compared. The corrosive environment of the battery has no effect on the thin-film sensor. The thin-film sensor can still provide stable performance under long-term conditions, thus meeting long-term testing needs.

[0052] At the same time, tests show that the thin film sensor's response to temperature has no obvious lag compared to the voltage change of the lithium-ion battery. Therefore, the thin film sensor can capture the temperature changes inside the lithium-ion battery.

[0053] The internal temperature measurement system of the lithium-ion battery of the embodiment of the present application includes a thin film sensor arranged inside the lithium-ion battery, and the thin film sensor includes multiple measurement points; a resistance acquisition device is used to connect with the multiple measurement points of the thin film sensor of the lithium-ion battery and obtain the resistance of the measurement points; a detection unit is used to obtain the temperature of the measurement point according to the resistance of each measurement point and the calibration curve of the measurement point, so as to detect multiple temperatures inside the lithium-ion battery. Through the above configuration, the embodiment of the present application integrates the thin film sensor into the lithium-ion battery, and the thin film sensor includes multiple measurement points, which can realize more comprehensive temperature detection inside the lithium-ion battery, and can more comprehensively understand the internal temperature of the lithium-ion battery, which provides a basis for analyzing the failure mechanism of the lithium-ion battery and improving the safety of the lithium-ion battery.

[0054] Furthermore, by integrating thin film sensors on the pole pieces of lithium-ion batteries, the principle of ion flow between positive and negative electrodes can be effectively used to display the changes in the internal temperature of lithium-ion batteries at different current rates in real time. Moreover, long-term cycle experiments have shown that attaching thin film sensors to the pole pieces of lithium-ion batteries has limited impact on the performance of lithium-ion batteries, and can achieve multi-point measurement of the internal temperature of lithium-ion batteries with minimal impact on the performance of lithium-ion batteries.

[0055] Furthermore, the present application also provides a method for measuring the internal temperature of a lithium-ion battery.

[0056] See attached Figure 3 , Figure 3 FIG. 1 is a flow chart showing the main steps of a method for measuring the internal temperature of a lithium-ion battery according to an embodiment of the present application. Figure 3 As shown, in the embodiment of the present application, a thin film sensor is arranged inside the lithium ion battery, and the thin film sensor includes a plurality of measuring points. The internal temperature measuring method of the lithium ion battery may include the following steps S201 to S203.

[0057] Step S201: a thin film sensor is arranged inside the lithium-ion battery to be tested, wherein the thin film sensor includes a plurality of measuring points.

[0058] Step S202: Connect multiple measuring points of the thin film sensor of the lithium-ion battery to a resistance acquisition device, and obtain the resistance of each measuring point.

[0059] Step S203: acquiring the temperature of each measuring point according to the resistance of each measuring point and the calibration curve of the measuring point, so as to detect multiple temperatures inside the lithium-ion battery.

[0060] In one embodiment, a lithium-ion battery may be prepared according to the following steps S101 to S103.

[0061] Step S101: removing active material from a preset area on the electrode.

[0062] In this embodiment, the active material in a preset area on the electrode can be removed.

[0063] Step S102: attaching a thin film sensor to the preset area where the active material is removed; wherein the thin film sensor includes a plurality of measuring points.

[0064] In this embodiment, a thin film sensor including a plurality of measurement points may be attached to a predetermined area where the active material is removed.

[0065] In one embodiment, a plurality of platinum measurement points may be deposited on a substrate by magnetron sputtering.

[0066] In an example, taking the electrode sheet as the positive electrode sheet as an example, the specific process of attaching the thin film sensor to the positive electrode sheet can be referred to in the attached Figure 2 , Figure 2 FIG. 1 is a schematic diagram of the main process of attaching a thin film sensor to a positive electrode sheet of a lithium-ion battery according to an embodiment of the present application. Figure 2 As shown, based on the principle of ion flow between the positive and negative electrodes, a small area of ​​electrode material (i.e., active material) is removed from the positive electrode sheet using N-methylpyrrolidone (NMP) solvent, and the width of the corresponding area where the active material is removed is slightly larger than the width of the thin film sensor, for example, the width can be 1 cm. The thickness of the area where the active material is removed is larger than the thickness of the thin film sensor, so that the area where the active material is removed can contain the thin film sensor in the thickness direction.

[0067] In one example, the number of measurement points can be seven, and a thin film sensor with seven measurement points can be attached to a preset area where the active material is removed. The thin film sensor can be located in the middle area of ​​the positive electrode sheet. Those skilled in the art can also set the number of measurement points according to the needs of actual applications.

[0068] Step S103: preparing a lithium-ion battery using a pole piece with a thin film sensor attached thereto; wherein a plurality of measuring points are used to detect the internal temperature of the lithium-ion battery.

[0069] In this embodiment, the electrode sheet with the thin film sensor attached thereto can be used to prepare a lithium-ion battery.

[0070] In one embodiment, before the thin film sensor is arranged inside the lithium-ion battery, the corresponding relationship between the resistance of each measuring point of the thin film sensor and the ambient temperature can be obtained; and a calibration curve of each measuring point can be obtained according to the obtained corresponding relationship.

[0071] Based on the method described in the above steps S201 to S203, the embodiment of the present application removes the active material in the preset area on the positive electrode sheet, and attaches a thin film sensor in the area corresponding to the removal of the active material, and uses the pole piece attached with the thin film sensor to prepare a lithium ion battery. The thin film sensor includes multiple measuring points, and the multiple measuring points are used to detect the internal temperature of the lithium ion battery. Through the above configuration, the embodiment of the present application integrates the thin film sensor into the lithium ion battery, and the thin film sensor includes multiple measuring points, which can realize more comprehensive temperature detection inside the lithium ion battery, and can more comprehensively understand the internal temperature of the lithium ion battery, which provides a basis for analyzing the failure mechanism of the lithium ion battery and improving the safety of the lithium ion battery. At the same time, the thin film sensor is integrated on the pole piece, which can effectively utilize the principle of ion flow between the positive and negative electrodes, and display the change of the internal temperature of the lithium ion battery at different current rates in real time. In addition, it is shown through long-term cycle experiments that attaching the thin film sensor to the pole piece of the lithium ion battery has limited impact on the performance of the lithium ion battery, and can realize multi-point measurement of the internal temperature of the lithium ion battery under the premise of minimizing the impact on the performance of the lithium ion battery.

[0072] Furthermore, the present application also provides a lithium-ion battery.

[0073] In an embodiment of a lithium ion battery according to the present application, the lithium ion battery is obtained according to the above-mentioned method for preparing a lithium ion battery.

[0074] Taking the thin film sensor in the lithium-ion battery with 7 measurement points as an example, the experiment shows that the internal temperature change of the lithium-ion battery during the discharge process at a discharge current of 2A shows that the internal temperature rise of the lithium-ion battery can reach about 10°C, and the maximum internal temperature is close to 35°C. The temperature change trends of the 7 measurement points are different, and the maximum temperature difference can reach 1°C. It can be seen that the temperature distribution inside the lithium-ion battery is uneven. In large-capacity and high-current lithium-ion batteries, temperature non-uniformity cannot be ignored.

[0075] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art can understand that in order to achieve the effect of the present application, different steps do not have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders. These adjusted schemes are equivalent to the technical schemes described in this application, and therefore will also fall within the scope of protection of this application.

[0076] It is understood by those skilled in the art that all or part of the processes in the method for implementing the above-mentioned embodiment of the present application can also be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium may include: any entity or device, medium, U disk, mobile hard disk, disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier signal, telecommunication signal and software distribution medium, etc. that can carry the computer program code.

[0077] So far, the technical solution of the present application has been described in conjunction with an embodiment shown in the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present application.

Claims

1. A lithium-ion battery internal temperature measurement system, characterized in that: include: A thin film sensor for being arranged inside the lithium ion battery, the thin film sensor comprising a plurality of measuring points; a resistance acquisition device, configured to be connected to a plurality of measurement points of the thin film sensor and acquire the resistance of each measurement point; The detection unit is configured to obtain the temperature of each measurement point according to the resistance of each measurement point and the calibration curve of the measurement point, so as to detect multiple temperatures inside the lithium-ion battery.

2. The internal temperature measurement system of a lithium-ion battery according to claim 1, characterized in that: When the thin film sensor is arranged inside the lithium ion battery, the thin film sensor is attached to a preset area on a pole piece of the lithium ion battery where active materials are removed; the pole piece is a positive electrode piece or a negative electrode piece.

3. The internal temperature measurement system of a lithium-ion battery according to claim 1, characterized in that: The thin film sensor comprises a stacked substrate and a covering layer, and the plurality of measuring points are arranged on a side of the substrate away from the pole piece.

4. The internal temperature measurement system of a lithium-ion battery according to claim 3, characterized in that: The substrate and the cover layer are both polyimide sheets.

5. The internal temperature measurement system of a lithium-ion battery according to claim 3, characterized in that: The measuring points are platinum measuring points formed by deposition on the substrate by magnetron sputtering.

6. The internal temperature measurement system of a lithium-ion battery according to claim 5, characterized in that: The width of the preset area is greater than the width of the thin film sensor; The thickness of the preset area is greater than the thickness of the thin film sensor; and / or, The thickness of the thin film sensor is less than 50 μm.

7. The internal temperature measurement system of a lithium-ion battery according to any one of claims 1 to 6, characterized in that: The calibration curve is generated before the thin film sensor is attached to the electrode, and is a curve representing the corresponding relationship between the resistance of each measuring point and the ambient temperature.

8. A method for measuring the internal temperature of a lithium-ion battery, characterized in that: The method comprises: A thin film sensor is arranged inside the lithium ion battery to be tested, wherein the thin film sensor includes a plurality of measuring points; Connecting multiple measuring points of the thin film sensor of the lithium ion battery to a resistance acquisition device, and obtaining the resistance of each measuring point; The temperature of each measuring point is obtained according to the resistance of each measuring point and the calibration curve of the measuring point, so as to detect multiple temperatures inside the lithium-ion battery.

9. The method for measuring the internal temperature of a lithium-ion battery according to claim 8, characterized in that: The lithium-ion battery is prepared according to the following steps: Removing active material from a preset area on the electrode; Attaching a thin film sensor to a preset area where the active material is removed; wherein the thin film sensor includes a plurality of measuring points; A lithium-ion battery is prepared using the pole piece with the thin film sensor attached thereto; wherein the multiple measurement points are used to detect the internal temperature of the lithium-ion battery.

10. The method for measuring the internal temperature of a lithium-ion battery according to claim 8, characterized in that: The method further comprises: Before the thin film sensor is arranged inside the lithium-ion battery, obtaining a corresponding relationship between the resistance of each measuring point of the thin film sensor and the ambient temperature; According to the corresponding relationship, a calibration curve of each measuring point is obtained.

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