Lithium ion battery fault on-line detection device for non-contact magnetic impedance measurement

Abstract

The invention discloses a lithium ion battery fault on-line detection device for non-contact magneto-impedance measurement. The device is composed of an operation host, a lock-in amplifier, a magnetic shielding barrel, a magnetic sensor probe group, a battery charging and discharging device, a lithium ion battery, a multi-degree-of-freedom non-magnetic micropositioner and a weak magnetic vibration isolation platform. Lithium electroplating of the lithium ion battery can generate metal lithium which is greatly different from electrode conductivity, and an internal conductivity algorithm based on magnetic field visualization can detect abnormal conductivity so as to detect occurrence of lithium electroplating; small current with specific frequency is superposed on charge and discharge current of the lithium ion battery, the magnetic sensor probe group scans magnetic field distribution on the surface of the battery to provide original data for a conductivity distribution calculation algorithm, and an upper computer sends a signal for changing a charging strategy to charging equipment according to a result to achieve the purpose of relieving lithium electroplating.

Description

Technical Field

[0001] This invention relates to a non-contact magnetoresistive measurement device for online fault detection of lithium-ion batteries, belonging to the field of novel intelligent sensing and manufacturing. Background Technology

[0002] Lithium-ion batteries, with their high energy density and long cycle life, have been widely used in electric vehicles, portable electronic devices, and energy storage systems, becoming a core power source. However, as market demand for fast charging technology continues to rise, the problem of lithium plating on the negative electrode caused by high-rate charging is becoming increasingly prominent. This phenomenon occurs when the charging current exceeds the diffusion rate of lithium ions in the graphite negative electrode, forcing lithium ions to be reduced to metallic lithium on the surface of the negative electrode instead of being embedded in the layered graphite structure.

[0003] Lithium plating refers to the phenomenon where lithium ions fail to properly embed into the graphite anode during charging and instead deposit directly as metallic lithium on its surface. The main contributing factors include high charging rates, low-temperature environments, and defects in the anode material: High charging rates: When the charging current exceeds the diffusion rate of lithium ions in graphite, lithium ions accumulate on the surface and undergo a deposition reaction; Low-temperature environments: At low temperatures, the viscosity of the electrolyte increases, the ion migration rate decreases, and the local overpotential rises, promoting lithium plating formation; Material defects: Inhomogeneous graphite structure or an incomplete SEI film (solid electrolyte membrane) can cause uneven local current density distribution, further inducing deposition.

[0004] Deposited lithium metal continuously reacts with the electrolyte, consuming active lithium and causing rapid capacity decay. Simultaneously, it damages the SEI film stability, increases interfacial impedance, and reduces long-term cycle performance. More seriously, the deposition process can form sharp lithium dendrites, which can penetrate the separator during growth, triggering internal short circuits or even thermal runaway. Current lithium-ion battery fault detection technologies mainly include voltage plateau analysis, differential capacity curve analysis (dQ / dV), and temperature sensing. However, these methods all have significant limitations: Voltage plateau analysis: While the negative offset of the charging end voltage can indirectly indicate plating, it has a large hysteresis and is severely affected by temperature and battery aging, resulting in significant errors; Differential capacity curve analysis: Requires sophisticated laboratory equipment, making real-time on-vehicle detection difficult; Temperature sensing: Can only capture the terminal signal when thermal runaway has already occurred.

[0005] In summary, traditional methods have shortcomings in terms of real-time performance, sensitivity, commercial feasibility, and quantitative analysis capabilities. With the widespread application of lithium-ion batteries, the market urgently needs a highly sensitive, real-time, and quantifiable fault detection technology. Based on this, this invention proposes a magnetoresistive lithium-ion battery fault detection device. This device utilizes a high-precision magnetic sensor to measure the magnetic field distribution during the battery's charging and discharging process in real time, and uses this to inversely determine the internal current density distribution of the battery, further establishing a mapping relationship between the magnetic field distribution and the local conductivity distribution. Based on an internal conductivity algorithm that visualizes the magnetic field, the occurrence of lithium plating can be accurately identified, and its severity can be assessed by quantifying the local abnormal conductivity. Since the magnetic signal generated during the lithium plating process is much weaker than the Earth's magnetic field strength, this invention designs a magnetic shielding barrel composed of multiple layers of permalloy plates on the outermost layer of the device to effectively shield external magnetic interference and ensure detection accuracy. Summary of the Invention

[0006] The present invention aims to solve the problems existing in the current lithium-ion battery testing process. The present invention designs and discloses a non-contact magnetoresistance measurement online fault detection device for lithium-ion batteries.

[0007] According to some embodiments of the present invention, a non-contact magnetoresistance measurement online fault detection device for lithium-ion batteries is disclosed. The host computer uses an industrial control computer as the core control unit, establishing a data and command connection with the battery charging and discharging equipment via a communication interface. The host computer software running on the host computer can control the battery charging and discharging equipment in real time. While executing the charging and discharging process, it superimposes a set frequency excitation signal onto the charging and discharging current, thereby performing precise charging and discharging operations on the lithium-ion battery and modulating and testing its dynamic electrochemical characteristics. Furthermore, the host computer is connected to the demodulation output of a lock-in amplifier via the communication interface, enabling data transmission and control command interaction. The host computer can receive, process, and store the weak magnetic signal collected by the lock-in amplifier in real time according to a preset excitation signal frequency, and can also issue control commands including frequency, phase, and gain to the lock-in amplifier. This design ensures efficient collaborative operation between the host computer and the lock-in amplifier in the signal acquisition, analysis, and control processes, thereby improving the overall measurement accuracy and stability of the system.

[0008] According to some embodiments of the present invention, a non-contact magnetoresistive measurement online fault detection device for lithium-ion batteries is provided. The magnetic shielding barrel is constructed from multi-layer permalloy plates, forming a cylindrical structure with an internal diameter of 1 m and a height of approximately 0.5 m. This structure effectively shields against external geomagnetic field interference, covering both static and low-frequency magnetic fields. The bottom of the magnetic shielding barrel is fixedly mounted on a weak magnetic vibration isolation platform integrally manufactured from glass fiber composite material. This platform possesses excellent non-magnetic properties, structural rigidity, and vibration reduction capabilities, effectively isolating mechanical vibrations generated by the ground and surrounding equipment. The synergistic effect of these two components suppresses the influence of external magnetic fields and significantly reduces vibration noise, providing a stable and low-noise experimental environment for high-sensitivity measurement of weak magnetic signals.

[0009] According to some embodiments of the present invention, a non-contact magnetoresistive measurement online fault detection device for lithium-ion batteries is disclosed. The magnetic sensor probe assembly comprises a non-magnetic support frame and four magnetic sensor probes. The main body of the support frame is integrally manufactured from high-strength non-magnetic material, ensuring structural stability and preventing interference with the magnetic field measurement. The four magnetic sensor probes are mounted on this frame and fixed at predetermined equidistant positions to ensure spatial consistency and geometric accuracy of each measurement point. Through this regularized layout, the magnetic sensor probe assembly can simultaneously acquire magnetic field data at multiple different spatial points, thereby obtaining high-resolution magnetic field distribution data. This data provides a reliable and accurate experimental basis for the visualization and imaging of weak magnetic signals in lithium-ion batteries, spatial distribution analysis, and subsequent electrochemical characteristic studies.

[0010] According to some embodiments of the present invention, a non-contact magnetoresistive measurement online fault detection device for lithium-ion batteries is provided, wherein the battery charging and discharging equipment consists of a DC power supply and an AC power supply. The DC power supply provides a stable and adjustable DC component for the entire battery charging and discharging equipment. The amplitude of this DC output is precisely controlled by the host computer to achieve the charging and discharging process of the lithium-ion battery under constant current or constant voltage conditions. The AC power supply can adjust the frequency, amplitude, and phase of the output AC signal according to control commands issued by the host computer, superimposing a set AC excitation component onto the DC charging and discharging circuit, thereby applying a specific frequency AC disturbance signal to the lithium-ion battery during operation. This combined AC and DC driving method can not only realize the conventional charging and discharging of the battery, but also be used to study its electrochemical and weak magnetic response characteristics under different frequency magnetic excitation conditions.

[0011] According to some embodiments of the present invention, a non-contact magnetoresistive measurement online fault detection device for lithium-ion batteries is provided, wherein the multi-degree-of-freedom non-magnetic displacement stage is made of high-strength non-magnetic material. Its structure mainly consists of a non-magnetic ceramic base, an x-axis displacement stage, a rotation stage around the z-axis, a sensor fixing beam gantry, and a piezoelectric ceramic displacement device.

[0012] According to some embodiments of the present invention, a non-contact magnetoresistive measurement online fault detection device for lithium-ion batteries is provided. The main structure of the weak magnetic isolation platform is integrally manufactured from high-strength glass fiber composite material. This material possesses excellent non-magnetic, lightweight, high-strength, corrosion-resistant, and environmental strain-resistant properties, effectively avoiding interference from the material itself to the weak magnetic signal. The platform as a whole undergoes precise vibration isolation and damping design, significantly attenuating low-frequency and high-frequency mechanical vibrations transmitted from the ground and generated during the operation of surrounding equipment. Simultaneously, its structural stability ensures the geometrical positioning accuracy of the magnetic shielding device and magnetic sensor mounted on the platform, providing a low-noise, repeatable experimental environment for high-sensitivity weak magnetic detection and long-term stable testing.

[0013] According to some embodiments of the present invention, a non-contact magnetoresistance measurement online fault detection device for lithium-ion batteries is characterized by the following features compared with the prior art:

[0014] (1) The non-contact magnetoresistance measurement lithium-ion battery fault online detection device disclosed in this invention can measure the change in magnetic field value caused by a specific frequency current loaded onto the lithium-ion battery from inside the charging power supply.

[0015] (2) The non-contact magnetoresistance measurement lithium-ion battery fault online detection device disclosed in this invention can apply an excitation that is adjustable and does not interfere with the charging and discharging process of the lithium-ion battery, and proposes a non-contact online measurement method. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement, as described in this invention.

[0017] Part numbers in the diagram: 1-Operating host, 2-Lock-in amplifier, 3-Magnetic shielding barrel, 4-Magnetic sensor probe group, 5-Battery charging and discharging equipment, 6-Lithium-ion battery, 7-Four-degree-of-freedom non-magnetic displacement stage, 8-Weak magnetic vibration isolation platform.

[0018] Figure 2 This is a schematic diagram of the magnetic sensor probe group of a non-contact magnetoresistance measurement lithium-ion battery fault online detection device in an embodiment of the present invention.

[0019] Part numbers in the diagram: 4-Magnetic sensor probe assembly, 4a-Magnetic sensor probe assembly without magnetic support frame, 4b-Magnetic sensor probe.

[0020] Figure 3 This is a schematic diagram of a four-degree-of-freedom non-magnetic displacement stage for an online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement, as described in this invention.

[0021] Part numbers in the diagram: 7-Four-degree-of-freedom non-magnetic displacement stage, 7a-Non-magnetic ceramic base, 7b-X-axis displacement stage, 7c-Z-axis rotary stage, 7d-Sensor fixing beam gantry, 7e-Piezoelectric ceramic displacement device. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the orientation descriptions, such as "up" and "down," are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In the description of the present invention, "multiple" refers to two or more. If "first" and "second" are mentioned, they are only for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the order of indicated technical features. In the description of the present invention, unless otherwise expressly limited, terms such as "set," "install," and "connect" should be interpreted broadly, and those skilled in the art can reasonably determine the specific meaning of the above terms in the present invention in combination with the specific content of the technical solution.

[0023] The present invention will now be described in further detail with reference to the accompanying drawings:

[0024] The host computer (1) uses an industrial control computer as the core control unit. According to the specific embodiment, the host computer (1) is selected from Huabei Industrial Control BIS-6620, which uses an Intel 12th generation Core processor, supports dual network ports, 4G / 5G module expansion, and wide voltage input (9~36V DC). The host computer (1) establishes a data and command connection with the battery charging and discharging device (5) through the communication interface. The host computer software running on the host computer (1) can control the battery charging and discharging device (5) in real time. While performing the charging and discharging process, it superimposes the excitation signal of the set frequency into the charging and discharging current, thereby performing precise charging and discharging operations on the lithium-ion battery (6) and realizing the modulation and testing of its dynamic electrochemical characteristics. In addition, the host computer (1) is connected to the demodulation output terminal of the lock-in amplifier (2) through the communication interface to realize the interaction of data transmission and control commands. According to the specific embodiment, the lock-in amplifier (2) is selected from Chengdu Jiujin Technology JY-LIA-1000. The host (1) can receive, process and store the weak magnetic signal collected by the lock-in amplifier (2) in real time according to the preset excitation signal frequency. At the same time, it can send control commands including frequency, phase and gain to the lock-in amplifier (2). This design ensures the efficient collaborative operation of the host (1) and the lock-in amplifier (2) in the process of signal acquisition, analysis and control, thereby improving the overall measurement accuracy and stability of the system.

[0025] The magnetic shielding barrel (3) is constructed from multi-layer permalloy plates and has a cylindrical structure with an internal space diameter of 1 m and a height of approximately 0.5 m. It can effectively shield against external geomagnetic field interference, and its shielding effectiveness covers the static and low-frequency magnetic field range. The bottom of the magnetic shielding barrel (3) is fixedly installed on a weak magnetic vibration isolation platform (8) made of glass fiber composite material. The weak magnetic vibration isolation platform (8) has excellent non-magnetic properties, structural rigidity, and vibration reduction performance, and can effectively isolate mechanical vibrations generated by the ground and surrounding equipment. The synergistic effect of the two suppresses the influence of the external magnetic field and significantly reduces vibration noise, providing a stable and low-noise experimental environment for high-sensitivity measurement of weak magnetic signals. The magnetic sensor probe group (4) consists of a non-magnetic support frame (4a) and four magnetic sensor probes (4b). The main body of the non-magnetic support frame (4a) is made of high-strength non-magnetic material, which ensures structural stability and avoids interference with magnetic field measurement. Four magnetic sensor probes (4b) are mounted on the non-magnetic support frame (4a) of the magnetic sensor probe group and fixed at predetermined equidistant positions to ensure the spatial consistency and geometric accuracy of each measurement point. According to a specific embodiment, the non-magnetic support frame (4a) of the magnetic sensor probe group is a polyetheretherketone (PEEK) material frame structure with one end orthogonally perpendicular. The frame structure has a groove for fixing the magnetic sensor probes (4b) at four positions: the X-direction cantilever, the Y-direction cantilever, the Z-direction cantilever, and the origin. After installation, the magnetic sensor probes (4b) can be fixed using the screw holes pre-drilled at the ends of the cantilever arms. Through this regularized layout, the magnetic sensor probe group (4) can simultaneously acquire magnetic field data at multiple different spatial points, thereby obtaining high-resolution magnetic field distribution data. The magnetic field strength measured by the magnetic sensor probe (4b) at the origin of the magnetic sensor probe group (4) is denoted as B0 = The magnetic field strength measured by the magnetic sensor probe (4b) at the cantilever in the X direction is denoted as B. x = The magnetic field strength measured by the magnetic sensor probe (4b) at the cantilever in the Y direction is denoted as B. y = The magnetic field strength measured by the magnetic sensor probe (4b) at the Z-direction cantilever is denoted as B. z = Therefore, the magnetic field gradient in the X direction can be calculated as B. x - B 0= The magnetic field gradient B in the Y direction can be solved. y - B 0= The magnetic field gradient B in the Z direction can be solved. z -B 0= These data provide a reliable and accurate experimental basis for the visualization imaging, spatial distribution analysis and subsequent electrochemical characteristic research of weak magnetic signals of lithium-ion batteries (6).

[0026] The battery charging and discharging device (5) consists of a DC power supply and an AC power supply. The DC power supply provides a stable and adjustable DC component for the entire battery charging and discharging device. The amplitude of the DC output is precisely controlled by the host (1) to realize the charging and discharging process of the lithium-ion battery (6) under constant current or constant voltage conditions. The AC power supply can adjust the frequency, amplitude and phase of the output AC signal according to the control command issued by the host (1), and superimpose the set AC excitation component onto the DC charging and discharging circuit, thereby applying a specific frequency AC disturbance signal to the lithium-ion battery (6) during operation. This combined AC and DC driving method can not only realize the conventional charging and discharging of the lithium-ion battery (6), but also be used to study its electrochemical and weak magnetic response characteristics under different frequency magnetic excitation conditions.

[0027] The multi-degree-of-freedom non-magnetic displacement stage (7) is made of high-strength non-magnetic material to ensure that the entire platform will not interfere with the weak magnetic measurement environment during operation. Its structure is mainly composed of a non-magnetic ceramic base (7a), an x-axis displacement stage (7b), a z-axis rotary stage (7c), a sensor fixing beam gantry (7d), and a piezoelectric ceramic displacement device (7e). Among them, the non-magnetic ceramic base (7a) has excellent dimensional stability and large mass, providing solid support for precision displacement; the x-axis displacement stage (7b) and the z-axis rotary stage (7c) respectively realize non-contact smooth motion of two degrees of freedom in the horizontal direction, significantly reducing mechanical friction and vibration noise; the sensor fixing beam gantry (7d) is used to stabilize the installation position of the magnetic sensor probe group (4) and maintain the accuracy and consistency of its measurement reference during multi-axis displacement. This multi-degree-of-freedom non-magnetic displacement stage (7) can realize high-precision, multi-directional probe positioning and adjustment in a weak magnetic experimental environment, providing a flexible, stable, and low-noise displacement platform for magnetic field spatial scanning and imaging.

[0028] The main structure of the weak magnetic vibration isolation platform (8) is made of high-strength glass fiber composite material. This material has excellent non-magnetic, lightweight, high-strength, corrosion-resistant, and environmental strain-resistant properties, which can effectively avoid the interference of the material itself on the weak magnetic signal. The weak magnetic vibration isolation platform (8) is designed with precise vibration isolation and damping, which can significantly attenuate the low-frequency and high-frequency mechanical vibrations transmitted from the ground and generated during the operation of surrounding equipment. At the same time, the structural stability of the weak magnetic vibration isolation platform (8) ensures the geometric position accuracy of the magnetic shielding barrel (3) and the magnetic sensor probe group (4) installed on the weak magnetic vibration isolation platform (8), providing a low-noise and repeatable experimental environment for high-sensitivity weak magnetic detection and long-term stable testing.

Claims

1. A non-contact magnetoresistive measurement device for online fault detection of lithium-ion batteries, characterized in that, The system includes the following components: the host (1) is connected to the demodulation output of the lock-in amplifier (2) via a communication line to receive the amplified weak magnetic data of the selected frequency and display it on the host interface; the two receiving signal lines of the lock-in amplifier (2) pass through the middle through hole of the multi-layer permalloy plate into the interior of the magnetic shielding barrel (3), where the signal input end is connected to the magnetic sensor probe (4) and the other reference input signal line is connected to the battery charging and discharging device (5); the lithium-ion battery (6) is placed on the table of the multi-degree-of-freedom non-magnetic displacement stage (7), and the magnetic sensor probe (4) is mounted on the gantry of the multi-degree-of-freedom non-magnetic displacement stage (7), and the magnetic shielding barrel (3) is placed on the weak magnetic vibration isolation platform (8).

2. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The host computer (1) is an industrial control computer. It is connected to the battery charging and discharging equipment (5) through a communication interface. The host computer software controls the battery charging and discharging equipment (5) and superimposes an excitation signal of a set frequency to charge and discharge the lithium-ion battery (6).

3. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 2, characterized in that: The host (1) is connected to the demodulation output of the lock-in amplifier (2) through the communication interface to exchange data and commands. It can complete the acquisition and storage of the weak magnetic signal at the set excitation signal frequency and send control commands to the lock-in amplifier, thereby realizing the coordinated operation of the system.

4. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The magnetic shielding barrel (3) is a barrel-shaped structure made of multi-layer permalloy plates. Its internal space is approximately 1m in diameter and 0.5m in length. Its bottom is installed on a weak magnetic vibration isolation platform (8) made of glass fiber composite material to achieve effective shielding and isolation of external magnetic signals.

5. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The magnetic sensor probe group (4) consists of four magnetic sensor probes (4b) and a non-magnetic support frame (4a) for the magnetic sensor probe group, wherein the main body of the non-magnetic support frame (4a) for the magnetic sensor probe group is made of high-strength non-magnetic material.

6. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 5, characterized in that: The four magnetic sensor probes (4b) on the magnetic sensor probe group (4) are mounted on the non-magnetic support frame (4a) of the magnetic sensor probe group. The spacing between each magnetic sensor probe (4b) is fixed to ensure the spatial consistency of the measurement position. The magnetic sensor probe group (4) can simultaneously acquire magnetic fields at multiple spatial points to form high-resolution magnetic field distribution data, providing a reliable basis for weak magnetic signal imaging and analysis of lithium-ion batteries (6).

7. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The battery charging and discharging device (5) is composed of a DC power supply (5a) and an AC power supply (5b). The DC power supply (5a) can provide a DC component to the battery charging and discharging device (5) as a whole. The intensity of the DC component is controlled by the host (1). The AC power supply (5b) can adjust the frequency of the output signal according to the instructions issued by the host (1) to apply an AC excitation component to the lithium-ion battery (6).

8. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The multi-degree-of-freedom non-magnetic displacement stage (7) is made of high-strength non-magnetic material and mainly consists of a non-magnetic base, a non-magnetic ceramic base (7a), an x-axis displacement stage (7b), a z-axis rotary stage (7c), a sensor fixing beam gantry (7d), and a piezoelectric ceramic displacement device (7e).

9. The online fault detection device for lithium-ion batteries using non-contact magnetoresistance measurement as described in claim 1, characterized in that: The main body of the weak magnetic vibration isolation platform (8) is made of glass fiber composite material. The structure of the weak magnetic vibration isolation platform (8) is designed with vibration isolation, which can significantly reduce the mechanical vibration introduced by the operation of the ground and surrounding equipment, and provide a stable installation and testing environment for high-sensitivity weak magnetic detection.

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