Lithium battery thermal runaway detection device and method based on hydrogen sensitive material

Abstract

The invention provides a lithium battery thermal runaway detection device and method based on a hydrogen sensitive material, and belongs to the technical field of thermal runaway early warning. Wherein the detection body comprises a hydrogen sensitive body which is palladium-silver alloy aerogel; a cavity is formed in the sleeve shell, and the sleeve shell is arranged outside the hydrogen sensitive body in a sleeving mode through the cavity; the sleeve shell is positioned in a shell of the lithium battery; the two pole pieces are conductive metal pieces and are attached to the surface of the hydrogen sensitive body, and the two pole pieces do not make contact with each other; one ends of the two enameled wires are respectively welded with the two pole pieces to realize electrical connection; the other end extends out of the casing; and the microcomputer circuit is used for monitoring the resistance value of the detection body, is arranged in the lithium battery shell and is connected with a battery management system (BMS). According to the scheme, the hydrogen sensitive body is arranged in the lithium battery shell and can be in direct contact with hydrogen without waiting for the hydrogen to be diffused to the lithium battery shell, so that the hysteresis problem is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal runaway warning, and in particular relates to a lithium battery thermal runaway detection device and method based on hydrogen-sensitive materials. Background Art

[0002] With the widespread adoption of lithium-ion batteries in consumer electronics, transportation, and energy storage systems, the risk of battery thermal runaway has become a significant research topic in the energy sector. During thermal runaway, uncontrolled electrochemical reactions trigger violent gas production. Hydrogen, a primary gaseous product, has a generation rate that positively correlates with the severity of the thermal runaway. However, existing early warning technologies based on hydrogen concentration monitoring have significant limitations: commercial hydrogen sensors are typically deployed external to the battery, requiring the lithium battery to undergo the complete physical process of internal gas production, shell rupture, and gas diffusion before they can detect hydrogen signals.

[0003] Specifically, the hydrogen generated in the early stages of thermal runaway must accumulate inside the battery to a pressure exceeding the shell's withstand pressure (typically 0.5-1.5 MPa), causing the shell to rupture and fail. This process can last from tens of seconds to several minutes. After the shell breaks, hydrogen diffuses into the external environment through the gaps between the battery modules. Its transmission rate is constrained by the flow field characteristics (natural convection / forced convection) and the spatial topology. In a typical battery pack layout, the time delay for hydrogen to diffuse to the external sensor can be from several seconds to tens of seconds.

[0004] The superposition of the above multiple delays causes the warning time of existing hydrogen monitoring technology to lag behind the starting moment of thermal runaway by 1-3 minutes, which cannot meet the early warning needs. Summary of the Invention

[0005] In order to overcome the problems in the prior art, the present invention proposes a lithium battery thermal runaway detection device and method based on hydrogen-sensitive materials.

[0006] In order to achieve the above-mentioned object, the present invention proposes the following technical solution: a lithium battery thermal runaway detection device based on hydrogen-sensitive material, comprising the following detection body and microcomputer circuit;

[0007] The test objects include:

[0008] The hydrogen sensor is a palladium-silver alloy aerogel that can react chemically with hydrogen and change the resistance value;

[0009] The casing has a cavity formed inside, and the casing is arranged on the outside of the hydrogen sensitive body by relying on the cavity; the casing is installed on the cover plate of the lithium battery and is located in the shell of the lithium battery;

[0010] The two pole pieces are conductive metal pieces located in the cavity of the housing and are attached to the surface of the hydrogen sensitive body without contacting each other.

[0011] Two enameled wires, one end of which is welded to the two pole pieces to achieve electrical connection; the other end extends out of the casing;

[0012] The microcomputer circuit is used to monitor the resistance of the detection body, is arranged in the lithium battery casing, and is connected to the battery management system BMS.

[0013] Furthermore, the microcomputer circuit includes:

[0014] The main control chip has an output end connected to a serial interface, which is provided on the outer surface of the lithium battery housing. The battery management system BMS provided outside the lithium battery is electrically connected to the serial interface via a data line; the battery management system BMS can read the resistance data monitored by the main control chip;

[0015] The voltage-stabilized power supply circuit is used to provide a stable voltage to the main control chip;

[0016] The constant current source circuit is electrically connected to the voltage-stabilized power supply circuit and can generate a stable current source;

[0017] The Kelvin bridge circuit, connected to the constant current source circuit, consists of resistors R15, R16, R8, R9, R14, RT2, and R16. The resistance of the hydrogen sensor is RT2.

[0018] The signal amplifier can amplify the voltage signal measured by the Kelvin bridge circuit and transmit it to the main control chip, which then determines the resistance of the hydrogen sensitive body based on the voltage signal.

[0019] The signal amplifier can amplify the voltage signal measured by the Kelvin bridge circuit and transmit it to the main control chip, which then determines the resistance of the hydrogen sensitive body based on the voltage signal.

[0020] Furthermore, the microcomputer circuit also includes a power supply voltage monitoring circuit, including an operational amplifier U6, and voltage-dividing resistors R11 and R12; it can divide the voltage of the voltage source BAT1 in the voltage-stabilized power supply circuit through resistors R11 and R12, and input it to the non-inverting terminal of the operational amplifier U6, the inverting terminal of the operational amplifier U6 is connected to the reference voltage, and the output terminal is connected to the input terminal of the main control chip through resistor R13; it detects whether the voltage of the voltage source BAT1 in the voltage-stabilized power supply circuit is lower than the reference voltage. If it is lower than the reference voltage, the voltage of the voltage source BAT1 is abnormal, otherwise it is normal; the battery management system BMS reads the voltage status of the voltage source BAT1 through the serial interface. When the voltage of the voltage source BAT1 is abnormal, it reminds relevant personnel to disassemble the lithium battery cover and inspect and replace the lithium battery.

[0021] Furthermore, the material of the shell is modified silica aerogel.

[0022] Furthermore, the pole piece is in the shape of a spherical cap.

[0023] Furthermore, the pole piece and the hydrogen sensor are both connected in the cavity of the housing by interference fit.

[0024] Furthermore, a method for detecting thermal runaway of a lithium battery based on hydrogen-sensitive materials comprises the following steps:

[0025] S1: When the lithium battery enters the early stage of thermal runaway, the resistance of the monitored hydrogen sensor will gradually increase over time;

[0026] S2: The lithium battery is judged to have entered the middle stage of thermal runaway, and the ratio of the change in the resistance of the hydrogen sensor over time, △R, to the original resistance R of the hydrogen sensor is greater than or equal to 50%;

[0027] S3: It is judged that the lithium battery has entered the late stage of thermal failure, and the resistance of the monitored hydrogen sensitive body is infinite.

[0028] The above technical solutions can achieve the following beneficial effects:

[0029] 1. In this solution, the hydrogen-sensitive material used to measure thermal runaway in lithium batteries is placed inside the battery. Hydrogen generated in the early stages of thermal runaway can directly penetrate the modified silica aerogel and come into contact with the hydrogen sensor. The hydrogen sensor reacts chemically with the hydrogen, and by monitoring the change in the resistance of the hydrogen sensor, thermal runaway can be detected promptly. Compared to traditional methods that place sensors outside the battery, this solution eliminates the problem of monitoring hysteresis.

[0030] 2. A modified silica aerogel was designed to wrap the hydrogen sensitive body. Due to the hydrophobicity of silica aerogel, the battery fluid inside the lithium battery will not corrode the hydrogen sensitive body.

[0031] 3. The spherical hydrogen sensor can reduce the resistance to the flow of hydrogen in all directions, and the spherical hydrogen sensor is easy to process in a regular shape. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is an exploded view of the device;

[0033] Figure 2 It is a schematic diagram of the overall structure of the device;

[0034] Figure 3 This is a schematic diagram of the installation of the device in the battery;

[0035] Figure 4 This is the circuit diagram of the device when measuring resistance;

[0036] Figure 5 It is a module diagram of this device.

[0037] 1. Hydrogen sensor; 2. Housing; 3. Electrode; 4. Enameled wire; 5. Hydrogen sensor; DETAILED DESCRIPTION

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0039] Example 1: Figure 1 and Figure 2 As shown, a lithium battery thermal runaway detection device based on hydrogen-sensitive materials includes a detection body, which includes the following structure:

[0040] The hydrogen sensor 5 is spherical in shape, made of metal, with a continuous surface curvature and no sharp edges. The spherical shape is chosen because the drag coefficient of a sphere is relatively low among regular geometric shapes, which helps reduce fluid (hydrogen) flow resistance and facilitates the dynamic interaction of hydrogen from all directions of the sphere to the other side. The hydrogen sensor 5 is made of an existing hydrogen-sensitive material, specifically the palladium-silver alloy aerogel mentioned in patent application number 202311453589.6 (entitled "Method for Preparing Metal Aerogel and Its Application in Recycling PET Plastics"). Aerogel is defined as a microscopic porous structure of a material that reacts chemically with hydrogen, thereby changing its resistance.

[0041] The housing 1 is formed by joining two identical shells. The housing 1 is cubic in shape, with a spherical cavity defined within it, slightly smaller than the volume of the hydrogen sensor 1. When the hydrogen sensor 5 is assembled into the housing 1, the housing 1 can undergo slight deformation, allowing the hydrogen sensor 5 to fit seamlessly within the cavity. The housing 1 is made of modified silica aerogel with a porosity of 80-99% and an average pore size distribution of 20-70 nanometers. The diameter of a hydrogen molecule is 0.289 nanometers, allowing hydrogen to diffuse freely through the housing. The modified silica aerogel (existing material) is prepared by modifying the silica aerogel through methoxylation and silanization (methyl silylation), with a compressive strength of 2-5 MPa, which can meet the aforementioned micro-deformation requirements and significantly improve its hydrophobicity, thereby preventing the electrolyte inside the lithium battery from directly contacting the hydrogen sensitive body 5.

[0042] Two electrode pieces 3, each attached to the surface of the hydrogen sensor, are conductive metal sheets with a thickness of 1 mm. They do not contact each other. To ensure a close fit between the electrode pieces and the hydrogen sensor surface, the electrode pieces 3 are shaped like spherical caps, representing the portion remaining after a hollow sphere is cut along a plane. The two electrode pieces 3 are located within the cavity of the casing 1. As the casing 1 deforms, the electrode pieces 3 are locked into the cavity of the casing 1 using an interference fit.

[0043] The two enameled wires 4 are copper wires with a varnished surface. One end of the two enameled wires 4 is welded to the two pole pieces to form an electrically connected structure, and the other end extends out of the housing 1.

[0044] like Figure 3 As shown, the detection body is bonded and fixed to the lower surface of the cover of the lithium battery. When the lithium battery is produced, the detection body is first connected to the cover of the lithium battery, and then the detection body is placed inside the shell of the lithium battery through the top opening of the lithium battery shell, and finally the top opening of the lithium battery is closed by the cover.

[0045] The detection device also includes a microcomputer circuit for monitoring the resistance of the hydrogen sensitive body; the microcomputer circuit is located inside the lithium battery casing, and the microcomputer circuit is led out through a preset wire inside the lithium battery. The led-out wire is connected in series with a serial interface on the outer surface of the lithium battery casing, and the serial interface is electrically connected to the BMS (battery management system) arranged outside the lithium battery through a data line.

[0046] like Figure 4 , the microcomputer circuit includes the following circuit parts:

[0047] The main control chip U5 uses an STM32F103C8 microcontroller; the output port of the main control chip U5 is connected to the serial interface P1, which is arranged on the outer surface of the lithium battery shell. The BMS is electrically connected to the serial interface P1 through a data line and can read the resistance data monitored by the main control chip U5.

[0048] In the regulated power supply circuit, voltage source BAT1 (9V) is filtered by a filter circuit consisting of capacitors C1, C2, and C3 before being input into linear regulator U1. Linear regulator U1 outputs a stable 5V DC voltage. C4 and C5 act as filter capacitors, further suppressing ripple and ensuring output voltage stability. The stable 5V DC voltage output by linear regulator U1 passes through capacitor U3 to produce a 3.3V DC voltage, which is electrically connected to the power supply terminal of the main control chip U5, providing power to the main control chip U5. Voltage source BAT1 is derived from a lithium battery, which is stepped down by a voltage divider circuit within the battery.

[0049] The constant current source circuit, consisting of U2A (LM358) and Q1 (2N2222), connects the 5V DC voltage output by linear regulator U1 to this constant current source circuit, forming a stable current source. Because the lithium battery voltage is constantly changing, the constant current source circuit provides a stable power supply for the subsequent Kelvin bridge.

[0050] Kelvin bridge circuit, resistors R15, R16, R8, R9, R14, RT2 and R16 form a Kelvin bridge circuit, where resistor RT2 is the resistance of the aforementioned hydrogen sensor 5. The two enameled wires of the hydrogen sensor are connected to points X and Y of the circuit diagram respectively. Since the resistance of resistor RT2 is relatively low, the overall -4 The resistance change is 10 -5 Therefore, a Kelvin bridge circuit is required to monitor the change in resistance.

[0051] Signal amplifier U4 measures the resistance of hydrogen sensor 5. Two wires connected to signal amplifier U4 amplify the measured voltage signal of RT2 and input it to the main control chip U5. Based on the value of the amplified voltage signal, main control chip U5 determines the resistance across RT2 and, therefore, the resistance of hydrogen sensor 5. The battery management system (BMS) reads the resistance value of hydrogen sensor 5 obtained by main control chip U5 through a serial interface to further determine thermal runaway conditions.

[0052] The power supply voltage monitoring circuit includes an operational amplifier U6 and voltage-dividing resistors R11 and R12. The voltage source BAT1 (9V) is divided by resistors R11 and R12 and input to the non-inverting terminal of operational amplifier U6. The inverting terminal of operational amplifier U6 is connected to a reference voltage, such as 6V (set manually). The voltage source is formed by dividing the lithium battery voltage. The output terminal is connected to the input terminal (PB0) of the main control chip U5 through resistor R13. When the voltage source BAT1 (9V) is higher than the set reference voltage (6V), it outputs a high level to the input terminal (PB0) of the main control chip U5, indicating that the battery voltage is normal. When the voltage source BAT1 is lower than the set reference voltage, it outputs a low level to the PB0 terminal of the main control chip U5, indicating that the battery voltage is abnormal. The battery control system (BMS) reads the status of the voltage source (BAT1) in the main control chip U5 through a serial interface. If the status is abnormal, a prompt is displayed on the terminal connected to the BMS, reminding relevant personnel to remove the corresponding lithium battery cover and inspect and replace the lithium battery.

[0053] Example 2: A method for detecting thermal runaway of a lithium battery based on hydrogen-sensitive materials, comprising the following steps:

[0054] S1: When a lithium battery enters the early stage of thermal runaway, hydrogen is generated inside the battery. After passing through the pores of the casing, the hydrogen comes into contact with the hydrogen sensor and produces a chemical reaction. As time goes by, the degree of the chemical reaction becomes more intense, and the resistance of the monitored hydrogen sensor gradually increases over time.

[0055] S2: Determine if the lithium battery has entered the middle stage of thermal runaway. Hydrogen fluoride gas is generated inside the lithium battery. The hydrogen fluoride gas will destroy the modified silica aerogel. The heat inside the battery quickly affects the hydrogen sensitive body, causing the resistance of the hydrogen sensitive body to increase rapidly. When the ratio of the change in the resistance of the hydrogen sensitive body over time, △R, to the original resistance R of the hydrogen sensitive body is greater than or equal to 50%, that is, △R / R ≥ 50%, it indicates that the lithium battery has entered the middle stage of thermal runaway.

[0056] S3: It is judged that the lithium battery has entered the late stage of thermal runaway. The modified silica aerogel is completely destroyed, causing the two pole pieces to lose the physical support of the casing. The two pole pieces are separated from the hydrogen sensitive body, causing the monitored hydrogen sensitive body to have infinite resistance, indicating that the battery has entered the late stage of thermal runaway.

[0057] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A lithium battery thermal runaway detection device based on hydrogen-sensitive materials, characterized in that: It includes the following detection body and microcomputer circuit; The test objects include: The hydrogen sensor is a palladium-silver alloy aerogel that can react chemically with hydrogen and change the resistance value; The casing has a cavity formed inside, and the casing is arranged on the outside of the hydrogen sensitive body by relying on the cavity; the casing is installed on the cover plate of the lithium battery and is located in the shell of the lithium battery; The two pole pieces are conductive metal pieces located in the cavity of the housing and are attached to the surface of the hydrogen sensitive body without contacting each other. Two enameled wires, one end of which is welded to the two pole pieces to achieve electrical connection; the other end extends out of the casing; The microcomputer circuit is used to monitor the resistance of the detection body, is arranged in the lithium battery casing, and is connected to the battery management system BMS.

2. A lithium battery thermal runaway detection device based on hydrogen-sensitive materials according to claim 1, characterized in that: The microcomputer circuit includes: The main control chip has an output end connected to a serial interface, which is provided on the outer surface of the lithium battery housing. The battery management system BMS provided outside the lithium battery is electrically connected to the serial interface via a data line; the battery management system BMS can read the resistance data monitored by the main control chip; The voltage-stabilized power supply circuit is used to provide a stable voltage to the main control chip; The constant current source circuit is electrically connected to the voltage-stabilized power supply circuit and can generate a stable current source; The Kelvin bridge circuit, connected to the constant current source circuit, consists of resistors R15, R16, R8, R9, R14, RT2, and R16. The resistance of the hydrogen sensor is RT2. The signal amplifier can amplify the voltage signal measured by the Kelvin bridge circuit and transmit it to the main control chip, which then determines the resistance of the hydrogen sensitive body based on the voltage signal.

3. A lithium battery thermal runaway detection device based on hydrogen-sensitive materials according to claim 2, characterized in that: The microcomputer circuit also includes a power supply voltage monitoring circuit, including an operational amplifier U6, and voltage-dividing resistors R11 and R12; it can divide the voltage of the voltage source BAT1 in the voltage-stabilized power supply circuit through resistors R11 and R12, and input it to the non-inverting terminal of the operational amplifier U6, the inverting terminal of the operational amplifier U6 is connected to the reference voltage, and the output terminal is connected to the input terminal of the main control chip through resistor R13; it detects whether the voltage of the voltage source BAT1 in the voltage-stabilized power supply circuit is lower than the reference voltage. If it is lower than the reference voltage, the voltage of the voltage source BAT1 is abnormal, otherwise it is normal; the battery management system BMS reads the voltage status of the voltage source BAT1 through the serial interface. When the voltage of the voltage source BAT1 is abnormal, it reminds relevant personnel to disassemble the lithium battery cover and inspect and replace the lithium battery.

4. A lithium battery thermal runaway detection device based on hydrogen-sensitive materials according to claim 3, characterized in that: The material of the shell is modified silica aerogel.

5. The lithium battery thermal runaway detection device based on hydrogen-sensitive materials according to claim 4, characterized in that: The pole piece is in the shape of a spherical cap.

6. The lithium battery thermal runaway detection device based on hydrogen-sensitive materials according to claim 5, characterized in that: The pole piece and the hydrogen sensor are both connected in the cavity of the casing by interference fit.

7. A method for detecting thermal runaway of a lithium battery based on a hydrogen-sensitive material, based on the device for detecting thermal runaway of a lithium battery based on a hydrogen-sensitive material according to claim 6, characterized in that: The following steps are involved: S1: When the lithium battery enters the early stage of thermal runaway, the resistance of the monitored hydrogen sensor will gradually increase over time; S2: The lithium battery is judged to have entered the middle stage of thermal runaway, and the ratio of the change in the resistance of the hydrogen sensor over time, △R, to the original resistance R of the hydrogen sensor is greater than or equal to 50%; S3: It is judged that the lithium battery has entered the late stage of thermal failure, and the resistance of the monitored hydrogen sensitive body is infinite.

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