In-situ pressure detection device and method for button lithium battery

Abstract

The invention discloses an in-situ pressure detection device and method for a button lithium battery, and belongs to the technical field of battery detection. The device comprises a pressure detection module, a high-conductivity flexible wire, a data processing module and an electrochemical test module, and the pressure detection module is arranged between a battery shell and an electrode plate of a to-be-detected battery and used for obtaining internal pressure data of the to-be-detected battery in the charging and discharging process; the data processing module and the electrochemical testing module are connected to the output end of the pressure detection module in parallel through a high-conductivity flexible wire, the high-conductivity flexible wire is used for transmitting internal pressure data to the data processing module and the electrochemical testing module, and the data processing module is used for generating pressure-time data according to the internal pressure data; the electrochemical test module is used for generating voltage-current-time data according to the internal pressure data. And the volume expansion and stress evolution law of the electrode material in the charging and discharging process can be quantitatively revealed.

Description

Technical Field

[0001] This invention relates to the field of battery testing technology, and in particular to an in-situ pressure testing device and method for button lithium batteries. Background Technology

[0002] With the development of high-energy-density battery systems (such as silicon-based anodes and lithium metal anodes), the huge volume effect and side reactions of electrodes during cycling have become key bottlenecks restricting their commercial application. Volume changes not only lead to electrode pulverization, repeated rupture and reconstruction of the solid electrolyte interphase (SEI) film, and consumption of active lithium, but also cause drastic fluctuations in internal battery pressure, and even cause deformation of the battery casing and failure of interfacial contacts, ultimately leading to rapid capacity decay and safety hazards.

[0003] Currently, in-situ characterization techniques for internal battery changes, such as in-situ X-ray diffraction (XRD) and transmission electron microscopy (TEM), while providing microstructural information, struggle to directly and quantitatively reflect macroscopic-scale mechanical behavior. Furthermore, these techniques are expensive and cannot be seamlessly integrated with conventional electrochemical testing. Existing battery devices with integrated pressure sensors also suffer from the following limitations:

[0004] Single-point measurement: can only obtain pressure information in a certain local area inside the battery, and cannot reflect the uniformity of stress distribution across the entire electrode interface. It may miss critical non-uniform expansion or stress concentration phenomena.

[0005] Signal drift: Sensors are prone to baseline drift under long-term cycling or temperature changes, which affects the long-term accuracy and reliability of data. Summary of the Invention

[0006] In view of this, the present invention provides an in-situ pressure detection device and method for coin cell lithium batteries, to solve the limitations of existing technologies such as single-point measurement and signal drift. To achieve the above objective, the present invention proposes an in-situ pressure detection device for coin cell lithium batteries, comprising: Pressure detection module, highly conductive flexible wire, data processing module, electrochemical testing module, and control module; The pressure detection module is positioned between the battery casing and the electrode plates of the battery under test. It is used to acquire the internal pressure data of the battery under test during charging and discharging. The data processing module and the electrochemical testing module are connected in parallel to the output of the pressure detection module via a highly conductive flexible wire. The highly conductive flexible wire is used to transmit the internal pressure data to the data processing module and the electrochemical testing module. The data processing module is used to generate pressure-time data based on the internal pressure data. The electrochemical testing module is used to generate voltage-current-time data based on the internal pressure data. The control module is used to receive the pressure-time data and the voltage-current-time data, and perform time series alignment and spatial interpolation calculations on the pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode plates. It also calculates the uniformity index of the stress distribution to evaluate the battery under test based on the uniformity index.

[0007] Optionally, it also includes: a flexible support pad, wherein the pressure detection module is fixed between the battery casing and the electrode sheet of the battery to be tested by means of the flexible support pad.

[0008] Optionally, the pressure detection module uses a piezoelectric film or metal strain gauge with a thickness of 20-100μm to convert mechanical stress signals into electrical signals.

[0009] Optionally, the data processing module includes a signal amplification circuit and a filtering circuit. The highly conductive flexible wire is used to transmit the internal pressure data to the signal amplification circuit of the data processing module, and the signal amplification circuit transmits the amplified internal pressure data to the filtering circuit.

[0010] Optionally, the pressure detection module is disposed between the battery casing and the electrode plate of the battery to be tested in a single-point or multi-point array structure.

[0011] Optionally, the battery casing of the battery to be tested is provided with a sealed channel, one end of the highly conductive flexible wire is connected to the output terminal of the pressure detection module, and the other end of the highly conductive flexible wire is connected to the data processing module and the electrochemical testing module through the sealed channel.

[0012] Optionally, the sealing channel includes an epoxy encapsulation layer and a fluororubber O-ring.

[0013] Secondly, this application provides an in-situ pressure detection method for coin cell lithium batteries, comprising: The internal pressure data of the battery under test during the charging and discharging process is obtained by a pressure detection module located between the battery casing and the electrode plates of the battery under test. The internal pressure data is transmitted to a data processing module and an electrochemical testing module via a highly conductive flexible wire. The data processing module generates pressure-time data based on the internal pressure data, and the electrochemical testing module generates voltage-current-time data based on the internal pressure data. The control module performs time series alignment and spatial interpolation calculations on pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode sheet, and calculates the uniformity index of the stress distribution, so as to evaluate the battery under test based on the uniformity index.

[0014] Implementing the embodiments of the present invention will have the following beneficial effects: Flexible support pads and a stabilized encapsulation structure effectively solve the signal drift problem that is common in traditional integrated sensors, ensuring the reliability and repeatability of data during long-term cyclic testing. This addresses issues in existing technologies, such as the inability of single-point measurements to reflect stress distribution, poor long-term sensor stability, and susceptibility to signal drift. It enables simultaneous and accurate acquisition and correlation analysis of the spatiotemporal evolution of the internal stress field of the battery under standard electrochemical testing conditions. It achieves simultaneous acquisition and deep fusion of electrical (voltage, current), mechanical (multi-channel stress), and temporal information, providing an unprecedentedly rich experimental dataset for constructing and validating accurate electrochemical-mechanical coupling models. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] in: Figure 1 This is a schematic diagram of the structure of an in-situ pressure detection device for a button lithium battery provided in an embodiment of this application; Figure 2 This is a flowchart illustrating the operation of an in-situ pressure detection method for button lithium batteries provided in an embodiment of this application. Figure 3 This is a voltage-stress-time synchronous change curve obtained from an in-situ pressure detection method for button lithium batteries provided in an embodiment of this application. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the 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 a limitation of the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal communication of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0019] like Figure 1 As shown, this application embodiment provides an in-situ pressure detection device for button-type lithium batteries, comprising: Pressure detection module, highly conductive flexible wire, data processing module, electrochemical testing module, and control module; The pressure detection module is positioned between the battery casing 1 and the electrode plate 2 of the battery under test. It is used to acquire the internal pressure data of the battery under test during the charging and discharging process. The data processing module and the electrochemical testing module are connected in parallel to the output end of the pressure detection module through the highly conductive flexible wire 4. The highly conductive flexible wire is used to transmit the internal pressure data to the data processing module and the electrochemical testing module. The data processing module is used to generate pressure-time data based on the internal pressure data. The electrochemical testing module is used to generate voltage-current-time data based on the internal pressure data. The control module is used to receive the pressure-time data and the voltage-current-time data, and perform time series alignment and spatial interpolation calculations on the pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode plate and calculate the uniformity index of the stress distribution, so as to evaluate the battery under test based on the uniformity index.

[0020] For example, when the data processing module generates pressure-time data based on the internal pressure data, the electrochemical testing module simultaneously acquires the battery's voltage-current-time data.

[0021] In one possible implementation, it further includes: a flexible support pad 3, wherein the pressure detection module is fixed between the battery casing 1 and the electrode plate 2 of the battery to be tested by the flexible support pad 3.

[0022] For example, the flexible support pad ensures that the mechanical force is transmitted to the sensing unit evenly and stably, and can also effectively buffer local stress concentration, thereby significantly suppressing the signal baseline drift caused by component creep or loosening, and ensuring the accuracy of long-term testing. A spring 6 is provided between the flexible support pad 3 and the battery case 1.

[0023] In one possible implementation, the pressure detection module 5 uses a piezoelectric thin film or metal strain gauge with a thickness of 20-100 μm to convert mechanical stress signals into electrical signals.

[0024] For example, highly sensitive piezoelectric films (such as PVDF) or metal strain gauges with a thickness of 20-100 μm can convert local mechanical stress signals into electrical signals.

[0025] In one possible implementation, the data processing module includes a signal amplification circuit and a filtering circuit. The highly conductive flexible wire is used to transmit the internal pressure data to the signal amplification circuit of the data processing module, and the signal amplification circuit transmits the amplified internal pressure data to the filtering circuit.

[0026] For example, an amplifier circuit and a filter circuit are used to eliminate high-frequency noise and enhance signal stability.

[0027] In one possible implementation, the pressure detection module is arranged in a single-point or multi-point array structure between the battery casing of the battery to be tested and the electrode plates of different polarities, with a diaphragm 7 provided.

[0028] For example, by using a multi-channel sensor array, in-situ, spatially resolved monitoring of the stress distribution at the electrode interface was achieved on the scale of a standard coin cell. This enables accurate identification of local stress concentration and expansion non-uniformity issues, providing a direct basis for electrode structure optimization.

[0029] In one possible implementation, the battery casing of the battery to be tested is provided with a sealed channel, one end of the highly conductive flexible wire is connected to the output terminal of the pressure detection module, and the other end of the highly conductive flexible wire is connected to the data processing module and the electrochemical testing module through the sealed channel.

[0030] In one possible implementation, the sealing channel includes an epoxy encapsulation layer and a fluororubber O-ring.

[0031] For example, to address the airtightness challenge posed by multiple leads, a multi-layer composite sealing solution is adopted, including epoxy resin-silicone composite encapsulation of the lead outlets and O-ring fluororubber seals on the battery casing mating surfaces, to ensure that the device has extremely high airtightness and excellent electrolyte compatibility during long-term cycle testing.

[0032] In one possible implementation, such as Figure 2 As shown, this application provides an in-situ pressure detection method for coin cell lithium batteries, comprising: S110. The internal pressure data of the battery under test during the charging and discharging process is obtained by a pressure detection module disposed between the battery case and the electrode plate of the battery under test. S120. The internal pressure data is transmitted to the data processing module and the electrochemical testing module via a highly conductive flexible wire. The data processing module is used to generate pressure-time data based on the internal pressure data, and the electrochemical testing module is used to generate voltage-current-time data based on the internal pressure data. S130. The control module performs time series alignment and spatial interpolation calculations on the pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode sheet, and calculates the uniformity index of the stress distribution, so as to evaluate the battery under test based on the uniformity index.

[0033] An exemplary in-situ pressure detection method for coin-type lithium batteries includes: Device assembly: In an inert atmosphere glove box, the battery components are sequentially stacked and assembled, and a multi-channel pressure detection module is embedded between the upper shell and the electrode sheet. Flexible support pads are used for alignment and fixation, ultimately completing the battery encapsulation and sealing. Synchronous testing: The electrochemical interface and pressure signal interface of the device are connected to an electrochemical workstation and a multi-channel data acquisition system, respectively. Under constant current charge-discharge or other test regimes, the electrochemical signal and multi-channel pressure signal are synchronously acquired. Data fusion and analysis: The acquired voltage-time-capacity data and multi-channel pressure-time data are time-series aligned and spatially interpolated to generate a stress distribution cloud map of the electrode sheet, and the uniformity index of the stress distribution is calculated. Mechanism study and performance evaluation: By correlating stress evolution curves (such as maximum stress, stress change amplitude, and distribution uniformity) with electrochemical performance parameters (such as capacity retention and coulombic efficiency), the influence of different electrode materials, conductive agent formulations, and structural designs on volume expansion behavior and stress dissipation mechanisms is quantitatively evaluated.

[0034] Preferably, a PVDF piezoelectric film with a sensitivity of 0.2-1.5 mV / kPa, a linearity error of less than 2%, a response time of less than 10 ms, and a thickness of less than 0.2 mm is used to ensure that it does not interfere with the internal structural layout of the battery. The sensing unit is tightly attached to the battery through a fixed support structure to form a stable force transmission path. When the battery experiences stress changes during charging and discharging due to the volume expansion of the active material, gas generation, or interface changes, the pressure detection module can sense the stress in real time and convert the force signal into an electrical signal output.

[0035] The signal transmission component includes a highly conductive wire and a sealed lead-out terminal. One end of the wire is connected to the pressure detection module, and the other end extends outside the battery casing. The signal transmission component is connected to an external signal acquisition system to achieve real-time acquisition and analysis of pressure signals.

[0036] The volume expansion or structural strain generated during battery charging and discharging leads to changes in internal pressure. This pressure signal is converted into an electrical signal by a pressure detection module and output to an external monitoring system in real time, enabling continuous detection and recording of internal battery stress. Verification has shown that the device of this invention exhibits excellent linear response (R²>0.995) within a pressure range of 0-500 kPa, with signal drift below ±3%. By synchronously acquiring battery voltage-current signals, the dynamic coupling relationship between the electrochemical reaction process and mechanical stress can be obtained, such as... Figure 3 As shown, this reveals the influence of different conductive agents, active materials, and structural designs on the electrode stress evolution behavior.

[0037] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

[0038] The above description discloses only preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. Therefore, equivalent variations made in accordance with the claims of the present invention are still within the scope of the present invention.

Claims

1. An in-situ pressure detection device for button-type lithium batteries, characterized in that, include: Pressure detection module, highly conductive flexible wire, data processing module, electrochemical testing module, and control module; The pressure detection module is positioned between the battery casing and the electrode plates of the battery under test. It is used to acquire the internal pressure data of the battery under test during charging and discharging. The data processing module and the electrochemical testing module are connected in parallel to the output of the pressure detection module via a highly conductive flexible wire. The highly conductive flexible wire is used to transmit the internal pressure data to the data processing module and the electrochemical testing module. The data processing module is used to generate pressure-time data based on the internal pressure data. The electrochemical testing module is used to generate voltage-current-time data based on the internal pressure data. The control module is used to receive the pressure-time data and the voltage-current-time data, and perform time series alignment and spatial interpolation calculations on the pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode plates. It also calculates the uniformity index of the stress distribution to evaluate the battery under test based on the uniformity index.

2. The in-situ pressure detection device for button-type lithium batteries as described in claim 1, characterized in that, Also includes: A flexible support pad is used to fix the pressure detection module between the battery casing and the electrode plate of the battery to be tested.

3. The in-situ pressure detection device for button-type lithium batteries as described in claim 1, characterized in that, The pressure detection module uses a piezoelectric thin film or metal strain gauge with a thickness of 20-100μm to convert mechanical stress signals into electrical signals.

4. The in-situ pressure detection device for button-type lithium batteries as described in claim 1, characterized in that, The data processing module includes a signal amplification circuit and a filtering circuit. The highly conductive flexible wire is used to transmit the internal pressure data to the signal amplification circuit of the data processing module, and the signal amplification circuit transmits the amplified internal pressure data to the filtering circuit.

5. The in-situ pressure detection device for button-type lithium batteries as described in claim 1, characterized in that, The pressure detection module is arranged in a single-point or multi-point array structure between the battery casing and the electrode plate of the battery to be tested.

6. The in-situ pressure detection device for button-type lithium batteries as described in claim 1, characterized in that, The battery casing of the battery to be tested is provided with a sealed channel. One end of the highly conductive flexible wire is connected to the output terminal of the pressure detection module, and the other end of the highly conductive flexible wire is connected to the data processing module and the electrochemical testing module through the sealed channel.

7. The in-situ pressure detection device for button-type lithium batteries as described in claim 6, characterized in that, The sealing channel includes an epoxy encapsulation layer and a fluororubber O-ring.

8. A method for in-situ pressure detection of button-type lithium batteries, characterized in that, include: The internal pressure data of the battery under test during the charging and discharging process is obtained by a pressure detection module located between the battery casing and the electrode plates of the battery under test. The internal pressure data is transmitted to a data processing module and an electrochemical testing module via a highly conductive flexible wire. The data processing module generates pressure-time data based on the internal pressure data, and the electrochemical testing module generates voltage-current-time data based on the internal pressure data. The control module performs time series alignment and spatial interpolation calculations on pressure-time data and voltage-current-time data to generate a stress distribution cloud map of the electrode sheet, and calculates the uniformity index of the stress distribution, so as to evaluate the battery under test based on the uniformity index.

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