Lithium battery micro short circuit semi-quantitative calibration method based on micron-sized metal powder injection
By injecting micron-sized metal powder into lithium batteries and subjecting them to vibration treatment and monitoring, the problems of uncontrollability and poor repeatability of micro-short circuit states in lithium batteries have been solved, enabling controllable micro-short circuit simulation and characterization, and supporting intelligent safety management of battery management systems.
Patent Information
- Application Number
- CN202511422725.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-30
- Publication Date
- 2026-02-06
AI Technical Summary
Existing technologies for inducing micro-short-circuit states in lithium batteries are uncontrollable, have poor repeatability, and are difficult to characterize, making it difficult to achieve 'slow-on, controllable magnitude, and structurally adjustable' micro-short-circuit state reconstruction, which limits the training and verification of battery management system (BMS) algorithms.
Micron-sized metal powder is injected between the positive and negative electrodes of a lithium-ion battery. By vibration treatment and static placement, the changes in capacity and internal resistance are monitored. Combined with scanning electron microscopy to observe the ablation traces on the electrode, a rule for determining the micro-short circuit level is established, realizing controllable and repeatable micro-short circuit simulation and characterization.
It achieves controllable and highly repeatable simulation and characterization of the micro-short circuit state of lithium batteries, provides high-quality sample input, and provides a foundation for early fault warning models and thermal runaway prediction of intelligent BMS. It is suitable for material failure mechanism analysis and cell structure disturbance immunity testing.
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Figure CN121477032A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of lithium battery micro-short circuit technology, specifically relating to a semi-quantitative calibration method for lithium battery micro-short circuits based on micron-level metal powder injection. Background Technology
[0002] In existing technologies, micro short circuits, as a type of internal fault with high concealment, complex induction mechanisms, and uncontrollable evolution, have been considered one of the important causes of thermal runaway and sudden failures in lithium batteries. Compared with external short circuits, micro short circuits are usually caused by microstructural defects such as lithium dendrites piercing the separator, creating residual metal particle inclusions, and local breakdown of separator pores, exhibiting characteristics of "slow degradation, weak early signals, and strong irreversibility." They form high-resistance conduction paths inside the battery, initially manifesting as a decrease in internal resistance, a slight temperature rise, and slow capacity decay, making them difficult to accurately identify using conventional BMS diagnostic algorithms. Without timely detection and intervention, micro short circuits can further exacerbate electrode side reactions, accelerate the degradation of active materials, and ultimately evolve into serious safety events. Current experimental research on micro short circuit faults mainly relies on methods such as needle penetration, mechanical extrusion, laser etching, electrothermal triggering, and external resistance loading to induce short circuit behavior. However, these methods often suffer from drawbacks such as high intensity, high trigger threshold, difficulty in process control, and high non-reproducibility, making it difficult to achieve "slow-onset, controllable magnitude, and adjustable structure" micro-short circuit state reconstruction. Furthermore, the difficulty in standardizing experimental samples limits the training, validation, and risk threshold design of battery management system (BMS) algorithms based on empirical data.
[0003] Therefore, it is necessary to construct a safe, controllable, and repeatable experimental method for simulating and characterizing micro-short-circuit faults, which can be used to systematically explore the evolution path of micro-short-circuit faults under different operating conditions, and provide high-quality, well-labeled sample inputs for fault early warning models and thermal runaway prediction logic in next-generation intelligent BMS. Summary of the Invention
[0004] The purpose of this invention is to provide a semi-quantitative calibration method for micro-short circuits in lithium batteries based on micron-level metal powder injection, which solves the technical problems of uncontrollable induction methods, poor repeatability, and difficult characterization of micro-short circuit states in lithium batteries in the prior art.
[0005] The technical solution of this invention to solve its technical problem is as follows: A semi-quantitative calibration method for micro-short circuits in lithium batteries based on micron-level metal powder injection includes the following steps: S1: Select micron-sized metal powder with a set particle size range and set mass as the short-circuit induction material; S2: Injecting metal powder into the active region between the positive and negative electrodes of a lithium-ion battery; S3: After vibrating the lithium-ion battery with injected metal powder, let the treated lithium-ion battery stand for a set time. S4: Perform charge-discharge cycles on the lithium-ion battery after it has been left to stand, monitor the changes in capacity and internal resistance of the lithium-ion battery, and determine whether a micro-short circuit has occurred in the lithium-ion battery. If so, end the charge-discharge cycle, disassemble the lithium-ion battery, observe the distribution of metal powder and the ablation marks on the electrode, characterize the degradation of the electrode material using a scanning electron microscope, and calibrate the micro-short circuit based on the set classification rules. Save the calibration results. If not, continue to step S4.
[0006] Preferably, in step S2, the channel for injecting metal powder into the active area between the positive and negative electrodes of the lithium-ion battery is: a powder injection hole opened in the top cover of the lithium-ion battery, avoiding the electrode area. The powder injection hole includes: a straight end, a sealing washer, and a screw. The straight end has an internal thread structure, and the straight end and the screw are connected by a thread. A sealing washer is provided between the straight end and the screw.
[0007] Preferably, the sealing gasket is made of polytetrafluoroethylene or silicone rubber.
[0008] Preferably, the set particle size range is 1–50 micrometers, and the set time is 24 hours.
[0009] Preferably, the set particle size range is 5–20 micrometers.
[0010] Preferably, the metal powder is: iron powder, copper powder, nickel powder, or iron-copper-nickel alloy powder.
[0011] Preferably, the lithium-ion battery is a prismatic lithium-ion battery.
[0012] Preferably, the injection method for injecting metal powder into the lithium-ion battery in step S2 is divided into: manual injection and mechanical injection. The manual injection is specifically: injection with a flexible syringe; the mechanical injection is specifically: injection with an automatic feeding system.
[0013] Preferably, the vibration treatment in step S3 specifically involves using an ultrasonic vibrator, a mechanical vibration table, or a magnetic stirring module to vibrate the lithium-ion battery, thereby changing the distribution position of the metal powder inside the battery.
[0014] Preferably, the specific monitoring methods for monitoring the capacity and internal resistance changes of the lithium-ion battery in step S4 include at least one of the following: open-circuit voltage change, constant voltage charging leakage curve, electrochemical impedance spectroscopy test, differential capacity curve analysis, or temperature rise curve tracking.
[0015] The beneficial effects of this invention are as follows: By selecting micron-sized metal powder with a set particle size range and mass as the short-circuit inducing material, high particle dispersion of the short-circuit inducing material is ensured; the metal powder is injected into the active region between the positive and negative electrodes of the lithium-ion battery; the micro-short-circuit characteristics of the lithium-ion battery are characterized; after vibrating the lithium-ion battery with injected metal powder, the treated lithium-ion battery is left to stand for a set time; vibration makes the metal powder uniformly distributed inside the lithium-ion battery, and standing is to stabilize the internal interface and induce potential micro-short circuits; thereby improving the accuracy of the measurement results. Finally, by performing charge-discharge cycles on the lithium-ion battery after standing, the capacity and internal resistance changes of the lithium-ion battery are monitored to determine whether a micro-short circuit has occurred. When a short circuit occurs, the charge-discharge cycle is ended, the lithium-ion battery is disassembled, the distribution of metal powder and electrode ablation marks are observed, the degradation of the electrode material is characterized by scanning electron microscopy, and the micro-short circuit is calibrated based on a set classification rule, and the calibration results are saved. By continuously measuring the mass of the short-circuit inducing material, this method simulates different levels of micro-short-circuit states in lithium-ion batteries, thereby calibrating and classifying the electrochemical response characteristics of lithium-ion batteries. This makes the induction of micro-short-circuit states in lithium batteries controllable, highly repeatable, and simple to characterize. This method is not only applicable to material failure mechanism analysis and cell structure disturbance tolerance testing, but can also serve as an experimental verification platform for micro-short-circuit fault identification algorithms in battery management systems (BMS), providing fundamental support for the intelligent safety management of large-scale energy storage systems. Attached Figure Description
[0016] Figure 1 This is a flowchart illustrating the semi-quantitative calibration method for lithium battery micro-short circuits based on micron-level metal powder injection according to the present invention. Figure 2 This is a schematic diagram of the relevant structure of the powder injection hole in this invention; Figure 3 This is a graph showing the changes in battery capacity and internal resistance caused by injecting 500mg of metal powder in Example 1. Figure 4 The graph shows the changes in battery capacity and internal resistance caused by injecting 2000mg of metal powder in Example 1. Figure 5 This is a schematic diagram of electrode ablation marks observed after disassembling a lithium-ion battery injected with 500mg of metal powder in Example 1. Figure 6 This is a schematic diagram of the electrode ablation marks observed after disassembling a lithium-ion battery injected with 2000mg of metal powder in Example 1. Figure 7 This is a schematic diagram of the degradation of the cathode material in a lithium-ion battery injected with 500mg of metal powder under a scanning electron microscope, as shown in Example 1. Figure 8 This is a schematic diagram of the degradation of the cathode material in a lithium-ion battery with 2000mg of metal powder injected, as shown under a scanning electron microscope in Example 1. Detailed Implementation
[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.
[0018] like Figure 1 As shown, this invention discloses a semi-quantitative calibration method for micro-short circuits in lithium batteries based on micron-level metal powder injection, comprising the following steps: S1: Select micron-sized metal powder with a defined particle size range and mass as the short-circuit induction material; the defined particle size range is 1–50 microns, and in practical applications, the specific particle size range is 5–25 microns to ensure good injection flowability and micro-short-circuit induction capability. The metal powder is iron powder, copper powder, nickel powder, or iron-copper-nickel alloy powder, and the lithium-ion battery is specifically a prismatic lithium-ion battery.
[0019] S2: As Figure 2 As shown, metal powder is injected into the powder injection hole 2, which is located on the top cover 1 of the lithium-ion battery, avoiding the electrode area. The metal powder flows into the active area between the positive and negative electrodes of the lithium-ion battery through the powder injection hole 2. The injection methods for injecting metal powder into the lithium-ion battery are divided into manual injection and mechanical injection. Manual injection specifically refers to injection using a flexible syringe; mechanical injection specifically refers to injection using an automatic feeding system. In practical applications, the metal powder generally needs to be dried before injection, for example, by drying it in a vacuum oven at 60°C for 12 hours, while simultaneously removing agglomerated particles through sieving to ensure uniform particle dispersion. After powder injection, the interface is sealed a second time using epoxy resin or chemical-resistant sealant. The powder injection hole 2 includes a straight head 3, a sealing gasket 4, and a screw 5. The straight head 3 has an internal thread structure, and the straight head 4 and the screw 5 are connected by a thread. A sealing gasket 4 is placed between the straight head 4 and the screw 5. The sealing gasket 4 is specifically made of polytetrafluoroethylene or silicone rubber.
[0020] S3: After vibrating the lithium-ion battery with injected metal powder, the treated lithium-ion battery is left to stand for a set time; the set time is 24 hours, to stabilize the internal structure, restore the electrolyte distribution, and promote the formation of potential short-circuit paths. The vibration treatment specifically involves using an ultrasonic vibrator, a mechanical vibration table, or a magnetic stirring module to vibrate the lithium-ion battery, causing the metal powder to change its distribution position inside the battery, thereby promoting a uniform distribution of the metal powder inside the battery.
[0021] S4: Perform charge-discharge cycles on the lithium-ion battery after it has been left to stand. Monitor the changes in capacity and internal resistance of the lithium-ion battery to determine if a micro-short circuit has occurred. If so, end the charge-discharge cycle, disassemble the lithium-ion battery, observe the distribution of metal powder and electrode ablation marks, characterize the electrode material degradation using a scanning electron microscope, and calibrate the micro-short circuit based on the set classification rules. Save the calibration results. If not, continue to step S4. The specific monitoring methods for changes in capacity and internal resistance of the lithium-ion battery include at least one of the following: open-circuit voltage change, constant voltage charging leakage curve, electrochemical impedance spectroscopy, differential capacity curve analysis, or temperature rise curve tracking.
[0022] Example 1: Taking metal powders with a particle size range of 5-25 micrometers and masses of 500 mg and 2000 mg respectively as examples, the specific calibration method is as follows: 1. Selection and processing of metal powders Metal powders with good conductivity and stability were selected, specifically those with a particle size range of 5-25 micrometers and masses of 500 mg and 2000 mg, respectively, to ensure good injection flowability and micro-short-circuit induction capability. Before injection, the metal powders were dried in a vacuum oven at 60°C for 12 hours, while agglomerated particles were removed by sieving to ensure uniform particle dispersion.
[0023] 2. Quantitative injection of metal powder into the powder injection hole Weigh out 500 mg and 2000 mg of metal powder using an electronic balance with an accuracy of 0.1 mg. Inject the metal powder into the active area between the positive and negative electrodes of the battery using a syringe. The injection process should be slow and uniform to avoid powder accumulation or scattering, ensuring that the powder covers or adheres closely to the electrode surface to facilitate the formation of a short-circuit path.
[0024] 3. Vibration and static treatment of lithium-ion batteries After powder injection, the battery undergoes a short-term vibration treatment, preferably using a mechanical vibration table or ultrasonic vibration device with a frequency of 3000 Hz for 3600 seconds, to promote uniform distribution of metal powder between the electrodes. After vibration, the battery is left to stand at room temperature for 24–48 hours to stabilize the internal structure, restore electrolyte distribution, and promote the formation of potential short-circuit paths.
[0025] 4. Loop Optimization and Performance Monitoring The treated battery underwent charge-discharge cycle induction testing, charging to 3.6V at a 1C rate and then discharging to 2.8V at a 1C rate, repeating this cycle at least 10 times. The following parameters were recorded in real-time during the test: Initial and final capacitance changes, impedance (Rat) changes; When a battery exhibits characteristics such as a significant decrease in capacity, a significant change in internal resistance, or abnormal temperature rise, it can be preliminarily determined that a micro-short circuit has occurred, at which point the charge-discharge cycle should be stopped. Figure 3 As shown, when 500mg of metal powder is injected, the impedance change curve of the lithium-ion battery shows a significant decrease in the thirteenth cycle. Figure 4 As shown, when 2000mg of metal powder is injected, the impedance change curve of the lithium-ion battery shows a significant decrease at the sixth cycle.
[0026] 5. Disassembly and Structural Characterization The specific disassembly needs to be performed in a safe and dry environment to remove the sample battery exhibiting abnormal signals. For example... Figure 5 , Figure 6 As shown, the distribution of metal powder inside the cell, the presence of ablation marks, conductive agent deposition, browning, or localized carbonization on the electrode surface can be observed. It can be seen that the lithium-ion battery with 500mg of metal powder injected has lighter ablation marks, less conductive agent deposition, and less browning or localized carbonization than the lithium-ion battery with 2000mg of metal powder injected. Scanning electron microscopy (SEM) was used to characterize the positive electrode in the abnormal area, analyzing the integrity of the particle structure, interface peeling, ablation depth, and the degree of damage to the conductive network. Figure 7 , Figure 8 As shown, obvious cracks and fractures appeared between the positive electrode active material particles; local areas showed particle aggregation, reconstruction and boundary destruction, and the lithium-ion battery with 500mg of metal powder injected was less affected than the lithium-ion battery with 2000mg of metal powder injected.
[0027] 6. Calibration of micro-short circuit level By combining the mass of the injected metal powder, the changes in battery electrochemical performance parameters, and the degree of damage to the electrode structure, a rule for determining the level of micro-short circuits is established. Specific rules for determining the level can be found in Table 1. Table 1 Reference Table for Level Judgment Rules After disassembling and structurally characterizing lithium-ion batteries injected with 500 mg and 2000 mg of metal powder respectively, the specific calibration results are as follows: When 500 mg of metal powder was injected, a slight change in internal resistance and a slight capacity decay were observed, which were classified as a slight micro-short circuit. When 2000mg of metal powder was injected, it showed a significant decrease in impedance, a decrease in capacity, and electrode ablation, which was classified as a moderate to severe micro-short circuit. This calibration system can serve as a standard data sample for training or validating micro-short circuit identification models in BMS, and can also be used for quantitative evaluation of cell structure optimization and safety assessment.
[0028] 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.
Claims
1. A semi-quantitative calibration method for micro-short circuits in lithium batteries based on micron-level metal powder injection, characterized in that, Includes the following steps: S1: Select micron-sized metal powder with a set particle size range and set mass as the short-circuit induction material; S2: Injecting metal powder into the active region between the positive and negative electrodes of a lithium-ion battery; S3: After vibrating the lithium-ion battery with injected metal powder, let the treated lithium-ion battery stand for a set time. S4: Perform charge-discharge cycles on the lithium-ion battery after it has been left to stand, monitor the changes in capacity and internal resistance of the lithium-ion battery, and determine whether a micro-short circuit has occurred in the lithium-ion battery. If so, end the charge-discharge cycle, disassemble the lithium-ion battery, observe the distribution of metal powder and the ablation marks on the electrode, characterize the degradation of the electrode material using a scanning electron microscope, and calibrate the micro-short circuit based on the set classification rules. Save the calibration results. If not, continue to step S4.
2. The semi-quantitative calibration method for lithium battery micro-short circuits based on micron-level metal powder injection according to claim 1, characterized in that, In step S1, the channel for injecting metal powder into the active area between the positive and negative electrodes of the lithium-ion battery is: a powder injection hole opened in the top cover of the lithium-ion battery, avoiding the electrode area. The powder injection hole includes: a straight end, a sealing washer, and a screw. The straight end has an internal thread structure, and the straight end and the screw are connected by a thread. A sealing washer is provided between the straight end and the screw.
3. The semi-quantitative calibration method for lithium battery micro-short circuits based on micron-level metal powder injection according to claim 2, characterized in that, The sealing gasket is specifically made of polytetrafluoroethylene or silicone rubber.
4. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 1, characterized in that, The set particle size range is 1–50 micrometers, and the set time is 24 hours.
5. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 4, characterized in that, The specified particle size range is 5–20 micrometers.
6. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 5, characterized in that: The metal powder is: iron powder, copper powder, nickel powder, or iron-copper-nickel alloy powder.
7. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 1, characterized in that: The lithium-ion battery is specifically a prismatic lithium-ion battery.
8. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 1, characterized in that: In step S2, the injection method for injecting metal powder into the lithium-ion battery is divided into two types: manual injection and mechanical injection. The manual injection is specifically injection using a flexible syringe; the mechanical injection is specifically injection using an automatic feeding system.
9. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 8, characterized in that, The vibration treatment in step S3 specifically involves using an ultrasonic vibrator, a mechanical vibration table, or a magnetic stirring module to vibrate the lithium-ion battery, thereby changing the distribution position of the metal powder inside the battery.
10. The semi-quantitative calibration method for lithium battery micro-short circuit based on micron-level metal powder injection according to claim 9, characterized in that, The specific monitoring methods for monitoring the capacity and internal resistance changes of the lithium-ion battery in step S4 include at least one of the following: open-circuit voltage change, constant voltage charging leakage curve, electrochemical impedance spectroscopy test, differential capacity curve analysis, or temperature rise curve tracking.