Method and device for analyzing harmful reaction in lithium ion battery
By implanting parasitic battery cells inside the lithium-ion battery and performing charging and discharging tests, the problem of difficult monitoring of parasitic batteries inside the lithium-ion battery is solved, real-time analysis and monitoring of harmful reactions inside the lithium-ion battery is realized, and the difficulty of safety risk assessment is reduced.
Patent Information
- Application Number
- CN202510093006.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-21
- Publication Date
- 2025-03-28
AI Technical Summary
The internal parasitic batteries of lithium-ion batteries are tiny and locally present, making it difficult to accurately collect and monitor their internal reactions in real time through conventional means, increasing the difficulty of safety risk assessment.
By applying an overvoltage between the positive and negative electrodes of the lithium-ion battery to be tested and the shell, the shell surface temperature is collected, the harmful reaction occurs, and the parasitic battery cell is implanted at this position to conduct a charge and discharge test to analyze the impact of the parasitic battery on the battery body.
Real-time analysis and monitoring of harmful reactions inside lithium-ion batteries is realized, and the internal reactions of parasitic batteries can be accurately collected and monitored, reducing the difficulty of safety risk assessment.
Smart Images
Figure CN119716551A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of lithium ion batteries, and in particular to a method and a device for analyzing harmful reactions inside lithium ion batteries. Background Art
[0002] Lithium-ion battery energy storage systems have prominent safety issues, and safety issues have become a key issue restricting their large-scale development. Existing lithium-ion batteries may have scratches and damage to the PET film during production, processing, transportation, and battery system integration. During system integration, improper installation operations or environmental factors (such as humidity and temperature) may also affect the performance of the PET film. In addition, the PET film will experience electrical and thermal aging during long-term use. The PET film will be affected by the electric field and heat generated inside the battery, causing its performance to gradually decline and its insulation performance to weaken. Electrical and thermal aging will also accelerate the chemical degradation of the PET film, further reducing its insulation effect and causing the insulation failure of the lithium-ion battery. Once a closed circuit is formed between the positive or negative electrode of the battery and the outer shell, it may trigger harmful processes and side reactions inside the battery, leading to irreversible degradation of the battery or even thermal runaway.
[0003] Existing technologies have found in research that after insulation failure, the internal reaction of the battery mainly exists between the battery shell and the battery cell. The electrolyte provides a migration channel for ions between the battery cell and the shell, which will form a parasitic battery composed of the battery shell and battery materials inside the main battery. Since the parasitic battery inside the battery is tiny and localized, it is difficult to accurately collect and monitor the internal reaction of the parasitic battery through conventional means, which increases the difficulty of safety risk assessment.
[0004] In view of the safety issues of lithium-ion battery energy storage systems, existing technologies mainly use the following methods to analyze harmful reactions: After a harmful reaction occurs, two methods are usually used for analysis: physical detection and chemical analysis. Use physical detection methods such as scanning electron microscopy (SEM) and X-ray diffraction (XRD) to observe the microstructure and chemical composition of battery materials. Use chemical analysis methods such as gas chromatography-mass spectrometry (GC-MS) and Fourier transform infrared spectroscopy (FTIR) to detect the gas composition and concentration generated during battery thermal runaway. The second is to conduct electrochemical performance testing. By measuring electrochemical performance parameters such as the remaining capacity and internal impedance of the battery, the health status and performance degradation of the battery are evaluated. Use in-situ testing technology to monitor the electrochemical reaction process inside the battery in real time, and detect and deal with abnormal reactions in a timely manner.
[0005] Before harmful reactions occur, two methods are usually used for analysis. One is thermal runaway simulation and early warning. A battery thermal runaway model is established to simulate the thermal runaway process of the battery under different conditions and evaluate its safety performance. By real-time monitoring of battery parameters such as temperature and voltage, and detecting characteristic gas production components, a thermal runaway early warning system is established to detect potential safety hazards in advance. The second is data analysis and intelligent diagnosis. Using big data and artificial intelligence technology, the operating data of the battery is deeply mined and analyzed to discover potential failure modes and failure patterns. Through the intelligent diagnosis system, real-time monitoring of the battery status and fault early warning are achieved to improve the safety and reliability of the battery system.
[0006] However, the above methods, either reverse analysis through results that have already occurred, or predictive analysis through data mining, still cannot solve the problem that the internal parasitic batteries are tiny and local, and the internal reactions of the parasitic batteries cannot be accurately collected and monitored in real time by conventional means. Summary of the invention
[0007] In view of the problems existing in the prior art, the present invention provides a method and device for analyzing harmful reactions inside lithium-ion batteries, which can analyze and monitor harmful reactions of normal lithium-ion batteries in real time, and obtain the influence mechanism of parasitic batteries triggered by insulation failure on the thermal runaway process of the battery body.
[0008] The present invention is achieved through the following technical solutions: The present invention provides a method for analyzing harmful reactions inside a lithium-ion battery, comprising: An overvoltage is applied between the positive and negative electrodes and the outer shell of the lithium-ion battery to be tested, and the surface temperature of the outer shell of the lithium-ion battery to be tested is collected; the surface position corresponding to the surface temperature exceeding the thermal runaway temperature threshold is determined as the position where the harmful reaction occurs; Corresponding to the location where the harmful reaction occurs, a parasitic battery unit is implanted inside the lithium battery to be tested; the parasitic battery unit includes positive and negative electrodes, a barrier and a metal sheet stacked in sequence; The parasitic battery cell is subjected to charge and discharge tests. During the charge and discharge tests, the surface temperature and voltage of the lithium-ion battery to be tested are collected, and compared with the surface temperature and voltage of the lithium-ion battery under normal conditions to obtain the influence of the parasitic battery cell on the lithium-ion battery to be tested.
[0009] Optionally, when overvoltage is applied between the positive and negative electrodes and the shell of the lithium-ion battery to be tested, any one of the application methods is adopted between the positive electrode of the battery and the battery shell, between the negative electrode of the battery and the battery shell, between the battery shell and the positive electrode of the battery, and between the battery shell and the negative electrode of the battery; the voltage is 3.3-1500V, and the current is 0-1000A.
[0010] Optionally, the implanting of the parasitic battery cell inside the lithium battery to be tested includes any one of the following implantation methods: The parasitic battery unit is parasitic on the side of the lithium-ion battery, and one side of the metal sheet is close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the side of the lithium-ion battery, with the positive and negative poles close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, and one side of the metal sheet is close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, with the positive and negative poles close to the lithium-ion battery cell to be tested.
[0011] Optionally, when the parasitic battery unit is charged and discharged, the charge and discharge circuit uses current flowing from the positive and negative electrodes to the metal sheet, or current flowing from the metal sheet to the positive and negative electrodes; the charge and discharge voltage is 1-1500V, the current is 1-1000A, and the charging time is 0-24 hours.
[0012] Optionally, the method further includes the step of disassembling the parasitic battery unit; after the charge and discharge test process is completed, the parasitic battery unit implanted inside the lithium-ion battery to be tested is disassembled, and the surface morphology and element distribution of the positive and negative electrodes of the parasitic battery unit and the side of the metal sheet close to the barrier are tested.
[0013] The present invention also provides a lithium-ion battery internal harmful reaction analysis device, including a parasitic battery unit implanted in the lithium-ion battery, the parasitic battery unit including positive and negative electrodes, a barrier and a metal sheet stacked in sequence, and pole ears conductively connected to the positive and negative electrodes and the metal sheet respectively; the pole ears are insulated from the lithium-ion battery shell and led out of the lithium-ion battery shell.
[0014] The present invention also provides a device for analyzing harmful reactions inside lithium-ion batteries, comprising an independently arranged parasitic battery, wherein the parasitic battery comprises positive and negative electrodes, a barrier and a metal sheet stacked in sequence, a parasitic battery shell wrapping the positive and negative electrodes, the barrier and the metal sheet, and an electrolyte in the parasitic battery shell that infiltrates the positive and negative electrodes, the barrier and the metal sheet; the electrolyte is the same as the electrolyte of the lithium-ion battery.
[0015] Optionally, the positive and negative electrodes are positive electrode sheets or negative electrode sheets; the positive electrode sheets include an aluminum foil current collector and a positive electrode material, and the negative electrode material includes a copper current collector and a negative electrode material; the positive electrode or negative electrode material is located on one side of the current collector close to the barrier or on both sides of the current collector.
[0016] Optionally, the positive electrode material is lithium iron phosphate or a ternary material, and the negative electrode material is hard carbon or graphite.
[0017] Optionally, the barrier is a porous material or a porous material with a thickness of 30 μm-3 cm, which is used to provide a channel for the migration of the electrolyte.
[0018] Compared with the prior art, the present invention has the following beneficial technical effects: The present invention applies overvoltage to generate heat inside the lithium-ion battery to be tested, thereby measuring the temperature rise of the lithium-ion battery. The temperature of the weak internal part rises faster and is prone to short circuit first. Therefore, by screening the thermal runaway temperature threshold, the location of the harmful reaction can be confirmed by temperature before ensuring the safety of the lithium-ion battery to be tested; and corresponding to the location of the harmful reaction, a parasitic battery unit is directly implanted inside the lithium-ion battery to be tested, and the local parasitic battery when the harmful reaction occurs is simulated by the parasitic battery unit structure that can actually be directly measured; the parasitic battery unit is charged and discharged, so as to obtain the internal reaction of the parasitic battery unit or the influence of the parasitic battery unit on the host battery failure or thermal runaway process, and equivalently analyze the harmful reaction characteristics between the battery cell and the shell triggered by insulation failure and the influence of the harmful reaction on the battery failure or thermal runaway process. It can directly perform real-time analysis and measurement, accurately collect and monitor the internal structure where the harmful reaction occurs, so as to directly control the process of the harmful reaction and the runaway, and obtain the influence mechanism of the harmful reaction. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 Schematic diagram of the structure of the parasitic battery unit described in the example of the present invention.
[0020] Figure 2 The present invention is a flowchart of a method for analyzing harmful reactions inside a lithium-ion battery in an example of the present invention.
[0021] Figure 3 This is a side implantation method of the parasitic battery unit described in the example of the present invention.
[0022] Figure 4 This is another side implantation method of the parasitic battery unit described in the example of the present invention.
[0023] Figure 5 This is a bottom implantation method of the parasitic battery unit described in the example of the present invention.
[0024] Figure 6 This is another bottom implantation method of the parasitic battery unit described in the example of the present invention.
[0025] In the figure: positive and negative electrodes 1, barrier 2, metal sheet 3, pole ear 4, battery cell 5, battery casing 6, battery positive electrode 7, battery negative electrode 8. DETAILED DESCRIPTION
[0026] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. These drawings are all simplified schematic diagrams, which only illustrate the basic structure of the present invention in a schematic manner, and therefore only show the structures related to the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.
[0027] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.
[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances.
[0029] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.
[0030] The present invention proposes a method for analyzing harmful reactions inside lithium-ion batteries. By constructing a parasitic principle battery consisting of a battery positive electrode 7 or a negative electrode and a metal shell, the parasitic battery unit is integrated inside the lithium-ion battery, and the harmful reaction between the battery cell 5 and the battery shell 6 triggered by insulation failure can be equivalent, and the influence mechanism of the parasitic battery triggered by insulation failure on the thermal runaway process of the battery body can be obtained. The analysis device includes a parasitic battery unit implanted inside the lithium-ion battery, or an independently arranged parasitic battery that can be charged and discharged separately.
[0031] The parasitic battery phenomenon is triggered inside the battery when the insulation ages; under different overvoltage application modes, the current flows from the positive and negative electrodes 1 to the battery casing 6 or from the battery casing 6 to the positive and negative electrodes 1, so the parasitic battery mainly occurs between the positive and negative electrodes 1 and the battery casing 6, so there are two types of parasitic battery structures, namely the positive electrode-casing parasitic battery and the negative electrode-casing parasitic battery. However, when the overvoltage is applied, the parasitic battery inside the battery is point-shaped and dispersed, and it is difficult to obtain the influence of the parasitic battery on the lithium-ion battery and the reaction characteristics of the parasitic battery inside. Therefore, the present invention provides a method and device for analyzing harmful reactions inside lithium-ion batteries, constructs a parasitic battery unit, an equivalent parasitic battery inside the battery triggered by insulation failure, and this parasitic battery unit is an equivalent amplification of the chemical reaction characteristics between the battery casing 6 and the battery cell 5 when the insulation fails. By artificially implanting a parasitic battery unit in the lithium-ion battery, the influence of the parasitic battery on the performance and safety of the lithium-ion battery can be analyzed.
[0032] The present invention provides a lithium-ion battery internal harmful reaction analysis device, comprising a parasitic battery unit implanted in the lithium-ion battery, the structure of which is as follows: Figure 1 As shown, this parasitic battery structure includes three parts: positive and negative electrodes 1, barrier 2 and metal sheet 3; positive and negative electrodes 1 are positive electrode sheets or negative electrode sheets, the positive electrode sheets include aluminum foil current collectors and positive electrode materials, and the positive electrode materials are lithium iron phosphate or ternary materials; the negative electrode materials include copper current collectors and negative electrode materials, and the negative electrode materials are hard carbon or graphite; the positive electrode or negative electrode materials are located on the side of the current collector close to the barrier 2 or on both sides of the current collector. The barrier 2 is a porous material or a porous material with a thickness of 30μm-3cm, which can be a diaphragm, a porous plate, a porous plastic, a porous rubber and a composite material thereof, and can provide a channel for the migration of the electrolyte. The metal sheet 3 is an iron sheet or an aluminum sheet, and the thickness is not limited. The electrolyte of the parasitic battery unit adopts the electrolyte of the implanted lithium-ion battery, and the parasitic battery unit leads the pole ear 4 to the lithium-ion battery shell 6 for charging and discharging operations, and an insulating device is provided between the pole ear 4 and the lithium-ion battery shell 6.
[0033] The present invention discloses a device for analyzing harmful reactions inside a lithium-ion battery, comprising an independently arranged parasitic battery. Based on the structure of the parasitic battery unit, the parasitic battery is wrapped with an aluminum-plastic film and a metal shell on the outside and can be assembled into button, soft-pack and hard-shell batteries. The inside of the parasitic battery is soaked with electrolyte, so that it can be charged and discharged independently.
[0034] The present invention provides a method for analyzing harmful reactions inside a lithium-ion battery. Figure 2 As shown, including, Step S1, applying an overvoltage between the positive and negative electrodes 1 and the battery housing 6 of the lithium-ion battery to be tested, collecting the surface temperature of the lithium-ion battery housing 6 to be tested; determining the surface position corresponding to the surface temperature exceeding the thermal runaway temperature threshold as the location where the harmful reaction occurs; Step S2, implanting a parasitic battery unit inside the lithium battery to be tested corresponding to the location where the harmful reaction occurs; the parasitic battery unit includes a positive and negative electrode 1, a barrier 2 and a metal sheet 3 stacked in sequence; Step S3, performing a charge and discharge test on the parasitic battery unit, collecting the surface temperature and voltage of the lithium-ion battery to be tested during the charge and discharge test, comparing the surface temperature and voltage of the lithium-ion battery under normal conditions, and obtaining the influence of the parasitic battery unit on the lithium-ion battery to be tested.
[0035] In step S1, applying overvoltage between the positive and negative electrodes 1 and the battery shell 6 of the lithium-ion battery to be tested is a key step; when the lithium-ion battery is working normally, its internal chemical reaction is carried out within a certain voltage range; when the overvoltage is applied, the chemical reaction inside the battery may be accelerated or abnormal, resulting in heat generation inside the battery; this abnormal increase in heat may trigger the thermal runaway of the battery, that is, the temperature inside the battery rises rapidly, so by collecting the temperature on the surface of the lithium-ion battery shell 6 to be tested, the thermal reaction of the battery under different overvoltage conditions can be monitored in real time. When the surface temperature at a certain position exceeds the preset thermal runaway temperature threshold, it means that harmful chemical reactions may have occurred near the position, such as short circuit, electrolyte decomposition, etc. Therefore, it is reasonable to determine this position as the location where harmful reactions occur. Among them, the thermal runaway temperature threshold is limited to the temperature before the thermal runaway of the lithium-ion battery to be tested, and the thermal runaway temperature threshold is lower than the thermal runaway temperature to ensure the safety and controllability of the test.
[0036] After determining the location of the harmful reaction, in step S2, a method of implanting a parasitic battery cell inside the lithium battery to be tested is proposed. The design of the parasitic battery cell includes a positive and negative electrode 1, a barrier 2, and a metal sheet 3 stacked in sequence. The purpose of this design is to introduce a controllable, small-scale chemical reaction environment inside the battery to simulate or amplify the effect of the harmful reaction.
[0037] The positive and negative electrodes 1 are the basis for the chemical reaction of the parasitic battery cell, while the barrier 2 is used to control the rate and range of the chemical reaction. The metal sheet 3 may serve as a conductive channel or be used to trigger a specific chemical reaction. By adjusting the parameters of the parasitic battery cell (such as the positive and negative electrode 1 materials, the properties of the barrier 2, the type and size of the metal sheet 3, etc.), the reaction characteristics of the parasitic battery cell can be precisely controlled, thereby achieving in-depth research on harmful reactions.
[0038] In step S3, the parasitic battery cell is charged and discharged to observe its influence on the overall performance of the lithium-ion battery under test. The charge and discharge test is an important method for evaluating battery performance. By simulating the charging and discharging process of the battery in actual use, key indicators such as voltage change and temperature change of the battery under different conditions can be understood.
[0039] During the test, the surface temperature and voltage of the lithium-ion battery to be tested are collected and compared with the data under normal conditions. This comparison can help researchers analyze the specific impact of parasitic battery cells on the overall performance of the battery, such as whether harmful reactions are aggravated, whether the battery's charge and discharge characteristics are changed, etc. Through these analyses, the harmful reaction mechanism inside lithium-ion batteries can be further understood, and a scientific basis can be provided for the safe design and improvement of batteries.
[0040] In summary, the above steps systematically studied the harmful reactions and their effects inside lithium-ion batteries by means of overvoltage stimulation, implantation of parasitic battery cells, and charge and discharge testing. This method not only helps to deeply understand the safety performance of batteries, but also provides strong support for the improvement and upgrading of battery technology.
[0041] Preferably, when an overvoltage is applied between the positive and negative electrodes 1 and the battery casing 6 of the lithium-ion battery to be tested, the test is performed by applying any one of the following between the battery positive electrode 7 and the battery casing 6, between the battery negative electrode 8 and the battery casing 6, between the battery casing 6 and the battery positive electrode 7, and between the battery casing 6 and the battery negative electrode 8. Different application methods can also be used for comparison; when the overvoltage is applied, the voltage is 3.3-1500V and the current is 0-1000A.
[0042] Preferably, harmful reactions generally occur on the side or bottom of the lithium-ion battery. Therefore, when implanting a parasitic battery unit inside the lithium battery to be tested, combined with the structural characteristics of the parasitic battery unit, any of the following implantation methods can be adopted: the parasitic battery unit is parasitic on the side of the lithium-ion battery, and one side of the metal sheet 3 is close to the lithium-ion battery cell 5 to be tested; the parasitic battery unit is parasitic on the side of the lithium-ion battery, and one side of the positive and negative electrodes 1 is close to the lithium-ion battery cell 5 to be tested; the parasitic battery unit is parasitic on the bottom of the lithium-ion battery, and one side of the metal sheet 3 is close to the lithium-ion battery cell 5 to be tested; the parasitic battery unit is parasitic on the bottom of the lithium-ion battery, and one side of the positive and negative electrodes 1 is close to the lithium-ion battery cell 5 to be tested.
[0043] Preferably, when the parasitic battery unit is charged and discharged, the current circuit when a harmful reaction occurs in a lithium-ion battery can be fully simulated. Therefore, in the charge and discharge circuit, the current flows from the positive and negative electrodes 1 to the metal sheet 3, or the current flows from the metal sheet 3 to the positive and negative electrodes 1; the charge and discharge voltage is 1-1500V, the current is 1-1000A, and the charging time is 0-24 hours.
[0044] Preferably, after comparing and analyzing the surface temperature and voltage of the lithium-ion battery, the parasitic battery unit can be disassembled to analyze its structural morphology to further obtain the process of the harmful reaction; specifically, after the charge and discharge test process is completed, the parasitic battery unit implanted inside the lithium-ion battery to be tested is disassembled to test the surface morphology and element distribution of the positive and negative electrodes 1 of the parasitic battery unit and the metal sheet 3 on the side close to the barrier 2.
[0045] Example 1 In combination with the actual testing process, the present invention provides a method for analyzing harmful reactions inside a lithium-ion battery, and performs the following analysis steps for harmful reactions inside the battery triggered by insulation failure.
[0046] 1. First, apply overvoltage between the positive electrode 7-shell, negative electrode-shell, shell-positive electrode, and shell-negative electrode of the lithium-ion battery. The voltage range is 3.3-1500V and the current is 0-1000A. The surface temperature of the lithium-ion battery shell 6 is collected, and the surface temperatures of the lithium-ion batteries are compared. The surface with the higher temperature before the thermal runaway of the lithium-ion battery is the surface where the parasitic battery is located. The position of the parasitic battery inside the lithium-ion battery is determined. Usually, the parasitic battery is located on the side or bottom of the lithium-ion battery.
[0047] 2. How are parasitic battery cells implanted inside lithium-ion batteries? Figure 3-6 As shown, there are four different implantation methods, namely: Figure 3 As shown, the parasitic battery unit is parasitic on the side of the lithium-ion battery, and one side of the metal sheet 3 is close to the lithium-ion battery cell 5; Figure 4As shown, the parasitic battery unit is parasitic on the side of the lithium-ion battery, and the positive and negative electrodes 1 are close to the lithium-ion battery cell 5; Figure 5 As shown, the parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, and one side of the metal sheet 3 is close to the lithium-ion battery cell 5; Figure 6 As shown, the parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, and one side of the positive and negative electrodes 1 is close to the lithium-ion battery cell 5. These methods distribute and simulate the influence of the chemical reaction on the lithium-ion battery shell 6 on the lithium-ion battery cell 5 and the influence of the chemical reaction on the lithium-ion battery cell 5 on the entire cell 5. In addition, the positive and negative electrodes 1 can be divided into two types, the positive electrode and the negative electrode, to simulate the influence of the reaction on the positive electrode on the entire cell 5 and the influence of the reaction on the negative electrode on the entire cell 5. The implantation position of the parasitic battery unit is determined according to the parasitic battery position measured experimentally. The parasitic battery unit leads to the pole ear 4 in the lithium-ion battery shell 6 for charging and discharging operations, and there is an insulation design between the pole ear 4 and the lithium-ion shell.
[0048] 3. After the parasitic battery unit is implanted, the parasitic battery is charged and discharged during the experimental test. The charging and discharging voltage is 1-1500V, the current is 1-1000A, and the charging time is 0-24 hours. The charging and discharging circuit includes two types: the current flows from the positive and negative electrodes 1 to the metal sheet 3, and the current flows from the metal sheet 3 to the positive and negative electrodes 1.
[0049] 4. During the application process, the surface temperature and voltage of the lithium-ion battery are collected to obtain the influence of the parasitic battery on the lithium-ion battery.
[0050] 5. After the application is completed, the parasitic battery unit can be disassembled inside the lithium-ion battery to test the surface morphology and element distribution of the positive and negative electrodes 1 and the metal sheet 3 of the parasitic battery unit close to the barrier 2.
[0051] The present invention forms a parasitic battery unit with the positive and negative electrodes 1 and the metal sheet 3, artificially constructs the parasitic battery structure, implants the parasitic battery unit into the lithium-ion battery, charges and discharges the parasitic battery unit, obtains the internal reaction of the parasitic battery or the influence of the parasitic battery on the failure or thermal runaway process of the host battery, and equivalently obtains the characteristics of the harmful reaction inside the battery when the insulation fails and the influence of the harmful reaction on the battery failure or thermal runaway process. It is of great significance to analyze the evolution of the internal surface interface of the battery triggered by the insulation failure and reveal the internal reaction mechanism of the battery induced by the insulation failure.
[0052] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.
[0053] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of this invention. The technical scope of this invention is not limited to the content in the specification, and the technology must be determined according to the scope of the claims.
[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.
Claims
1. A method for analyzing harmful reactions inside a lithium-ion battery, characterized in that: include, An overvoltage is applied between the positive and negative electrodes and the outer shell of the lithium-ion battery to be tested, and the surface temperature of the outer shell of the lithium-ion battery to be tested is collected; the surface position corresponding to the surface temperature exceeding the thermal runaway temperature threshold is determined as the position where the harmful reaction occurs; Corresponding to the location where the harmful reaction occurs, a parasitic battery unit is implanted inside the lithium battery to be tested; the parasitic battery unit includes positive and negative electrodes, a barrier and a metal sheet stacked in sequence; The parasitic battery cell is subjected to charge and discharge tests. During the charge and discharge tests, the surface temperature and voltage of the lithium-ion battery to be tested are collected, and compared with the surface temperature and voltage of the lithium-ion battery under normal conditions to obtain the influence of the parasitic battery cell on the lithium-ion battery to be tested.
2. A method for analyzing harmful reactions inside a lithium-ion battery according to claim 1, characterized in that: When overvoltage is applied between the positive and negative electrodes and the shell of the lithium-ion battery to be tested, any one of the application modes is adopted: between the positive electrode of the battery and the battery shell, between the negative electrode of the battery and the battery shell, between the battery shell and the positive electrode of the battery, and between the battery shell and the negative electrode of the battery; the voltage is 3.3-1500V, and the current is 0-1000A.
3. A method for analyzing harmful reactions inside a lithium-ion battery according to claim 1, characterized in that: The implantation of the parasitic battery cell inside the lithium battery to be tested includes any of the following implantation methods: The parasitic battery unit is parasitic on the side of the lithium-ion battery, and one side of the metal sheet is close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the side of the lithium-ion battery, with the positive and negative poles close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, and one side of the metal sheet is close to the lithium-ion battery cell to be tested; The parasitic battery unit is parasitic on the bottom surface of the lithium-ion battery, with the positive and negative poles close to the lithium-ion battery cell to be tested.
4. A method for analyzing harmful reactions inside a lithium-ion battery according to claim 1, characterized in that: When the parasitic battery unit is charged and discharged, the charge and discharge circuit uses current flowing from the positive and negative electrodes to the metal sheet, or current flowing from the metal sheet to the positive and negative electrodes; the charge and discharge voltage is 1-1500V, the current is 1-1000A, and the charging time is 0-24 hours.
5. The method for analyzing harmful reactions inside a lithium-ion battery according to claim 1, characterized in that: The method also includes the step of disassembling the parasitic battery unit; after the charge and discharge test process is completed, the parasitic battery unit implanted inside the lithium-ion battery to be tested is disassembled to test the surface morphology and element distribution of the positive and negative electrodes of the parasitic battery unit and the side of the metal sheet close to the barrier.
6. A device for analyzing harmful reactions inside a lithium-ion battery, characterized in that: It includes a parasitic battery unit implanted in a lithium-ion battery, wherein the parasitic battery unit includes positive and negative electrodes, a barrier and a metal sheet stacked in sequence, and pole ears conductively connected to the positive and negative electrodes and the metal sheet respectively; the pole ears are insulated from the lithium-ion battery shell and are led out of the lithium-ion battery shell.
7. A device for analyzing harmful reactions inside a lithium-ion battery, characterized in that: The invention comprises an independently arranged parasitic battery, wherein the parasitic battery comprises a positive and negative electrode, a barrier and a metal sheet which are sequentially stacked, a parasitic battery shell which wraps the positive and negative electrode, the barrier and the metal sheet, and an electrolyte which infiltrates the positive and negative electrode, the barrier and the metal sheet in the parasitic battery shell; The electrolyte is the same as the electrolyte of lithium ion batteries.
8. A lithium-ion battery internal harmful reaction analysis device according to claim 6 or 7, characterized in that: The positive and negative electrodes are positive electrode sheets or negative electrode sheets; the positive electrode sheets include an aluminum foil current collector and positive electrode materials, and the negative electrode materials include a copper current collector and negative electrode materials; the positive electrode or negative electrode materials are located on the side of the current collector close to the barrier or on both sides of the current collector.
9. A lithium-ion battery internal harmful reaction analysis device according to claim 8, characterized in that: The positive electrode material is lithium iron phosphate or a ternary material, and the negative electrode material is hard carbon or graphite.
10. A lithium-ion battery internal harmful reaction analysis device according to claim 6 or 7, characterized in that: The barrier is a porous material or a porous material with a thickness of 30 μm-3 cm, and is used to provide a channel for the migration of the electrolyte.