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CN-122017119-A - Test method for electrochemical energy storage device

CN122017119ACN 122017119 ACN122017119 ACN 122017119ACN-122017119-A

Abstract

The application relates to the technical field of electrochemical energy storage devices, in particular to a testing method of a lithium/sodium ion battery and a supercapacitor, which comprises the steps of introducing a copper wire as a reference electrode in the manufacturing process of the electrochemical energy storage device, connecting the reference electrode with a cathode of charge-discharge equipment, connecting an anode of the energy storage device with an anode of the charge-discharge equipment, and running a constant current charging program, testing the electrochemical energy storage device by a constant current intermittent titration GITT technology, selecting an energy storage device monomer after working condition testing or after continuous running for a long time, re-performing a three-electrode test and a GITT test, and drawing a corresponding voltage curve graph and a GITT curve graph. Through GITT curve comparison before and after circulation, accurate tracing of an attenuation mechanism is realized, and the potential change of a working electrode and a counter electrode is accurately separated by combining a three-electrode system, so that the accurate analysis of aging and failure reasons is realized.

Inventors

  • LU JIANQI
  • LIU MINGZU
  • YAN KUN
  • MIN MIN
  • LI MIN
  • SUN WEI
  • LV BIN

Assignees

  • 烯晶碳能电子科技无锡有限公司

Dates

Publication Date
20260512
Application Date
20251128

Claims (10)

  1. 1. A testing method for an electrochemical energy storage device is characterized in that step 1, a copper wire is introduced as a reference electrode in the manufacturing process of the electrochemical energy storage device; step 2, connecting a reference electrode with a cathode of a charge-discharge device, connecting an anode of an energy storage device with the anode of the charge-discharge device, running a constant-current charging program, and plating lithium to the reference electrode with small current; step 3, testing the electrochemical energy storage device by using a constant current intermittent titration GITT technology, wherein an ion diffusion calculation formula is as follows: ; wherein V is the volume of the electrode material after coating, epsilon is the porosity, sb is the contact area of the electrode material and electrolyte, mb is the mass of the electrode material, deltaEs is the voltage change during relaxation, deltaEt is the voltage change during charge/discharge; And 4, selecting an energy storage device monomer after working condition test or after continuous operation for a long time, re-performing a three-electrode test and a GITT test, and drawing a corresponding voltage curve graph and a GITT curve graph.
  2. 2. The method according to claim 1, wherein the electrochemical energy storage device is a cylindrical hybrid supercapacitor, the anode of which is made of a conventional battery anode material, the energy is stored and released by electrochemical reaction, and the cathode of which is made of an electric double layer capacitor material.
  3. 3. The method according to claim 1, wherein step 1 further comprises cutting the prepared enameled copper wire to a proper length, controlling the length to be 0.5-1.5 times of the height of the battery, rapidly burning both ends of the copper wire with flame to remove a surface paint film and prevent the copper wire from breaking completely, immersing the treated part of the copper wire in a dilute sulfuric acid/hydrochloric acid solution to remove burning marks until the treated part shows a smooth and bright copper color, immersing the treated copper wire in an ethanol solution for standby, and preventing oxidation.
  4. 4. The test method according to claim 3, wherein the step 1 further comprises drilling a small hole with a diameter of 1mm on the surface of the shell, processing burrs around the hole for standby, unwinding an outer layer after winding of the inner core is completed, placing the processed copper wire between the positive and negative pole pieces, adding a layer of diaphragm to prevent short circuit, completely covering the processed copper wire between the diaphragms, leading out the copper wire from the hole after the inner core is put into the shell, welding a nickel tab at the other end of the copper wire, and fixing the nickel tab on the shell, thereby ensuring that the subsequent production process is not affected, and the copper wire is not destroyed.
  5. 5. The test method of claim 1, wherein the step 2 further comprises controlling the charging current to be 10-200 mu A, controlling the charging time to be 4-10h, connecting the charging and discharging equipment to the negative end of the energy storage device when the flow is finished, charging again by the program to ensure that the copper wire is completely plated with lithium, connecting the energy storage device to the charging and discharging equipment normally, connecting the data collector to the energy storage device, respectively monitoring the positive electrode-reference voltage and the negative electrode-reference voltage, and running the test program to test the energy storage device.
  6. 6. The test method according to claim 1, wherein the step 3 further comprises the step of placing the energy storage device in a constant temperature cabinet at 25 ℃ for 5 hours, and then starting to run a GITT test program, wherein the test program 1 is that the energy storage device is charged/discharged at 10C current, the pulse time is set to 9s each time, the pulse cycle is set to 40 times, the test program 2 is that the energy storage device is charged/discharged at 20C current, the pulse time is set to 9s each time, the pulse cycle is set to 20 times, and an initial GITT graph is drawn according to the result obtained by the test.
  7. 7. The test method according to claim 6, wherein the whole charge-discharge interval is 0% or less and SOC 100% or more.
  8. 8. The method of claim 1, wherein the electrochemical energy storage device is a soft pack hybrid supercapacitor cell.
  9. 9. The testing method of claim 8, wherein step 1 further comprises the steps of expanding the outermost negative electrode sheet after lamination of the inner core of the soft-packed battery is completed, placing the treated copper wire end between the positive electrode and the negative electrode, adding a layer of diaphragm to prevent short circuit, fully covering the treated copper wire part between the diaphragms and enabling the copper wire placing position to be parallel to the positive electrode lug and the negative electrode lug, punching the aluminum plastic film into a concave cavity by a punching machine, placing the inner core into the concave cavity, and ensuring that the electrode lug and the copper wire are exposed from the opening end of the aluminum plastic film.
  10. 10. The test method of claim 9, wherein step 1 further comprises cutting two polyethylene sealing films to clamp the copper wire at the center before pre-sealing, aligning the heat sealing positions to prevent the copper wire from being damaged in the pre-sealing process, and welding a nickel tab at the other end of the copper wire after the pre-sealing is completed and fixing the nickel tab on an aluminum plastic film at the outer side to ensure that subsequent production is not affected and the copper wire is not damaged.

Description

Test method for electrochemical energy storage device Technical Field The invention relates to the technical field of electrochemical energy storage devices, in particular to a testing method of a lithium/sodium ion battery and a supercapacitor. Background Electrochemical energy storage devices such as super capacitors have large-scale application in energy storage systems, vehicle-mounted starting power supplies and the like due to excellent electrochemical performance and long cycle life, but the performance of batteries is inevitably gradually reduced along with continuous increase of service time and continuous accumulation of charge and discharge cycle times, and the performance attenuation phenomenon is generally manifested by capacity loss, increase of internal resistance and reduction of charge and discharge efficiency. The accurate evaluation of the aging state of the electrochemical energy storage device has important significance for predicting the residual service life, optimizing the actual use working condition of the energy storage device and guaranteeing the safe and stable operation of related equipment. In a large-scale energy storage system, the overall operation efficiency and reliability of the system can be improved by reasonably scheduling according to the aging state of the battery, and in a vehicle-mounted electrochemical energy storage device, the aging state is accurately evaluated, so that potential safety hazards caused by sudden failure can be avoided. The aging/failure of the electrochemical energy storage device is a very complex process, relates to a plurality of chemical reactions and physical processes, and cannot comprehensively, deeply and accurately analyze the complex mechanism in the aging process of the energy storage device only by a common method of monitoring the voltage, capacity, internal resistance and the like of a battery, so that the actual aging condition of the anode and cathode materials under the combined action of a plurality of complex factors is difficult to accurately reflect, and the problem of inaccurate evaluation exists. In the prior art, the aging degree is quantified by comparing basic parameters such as capacity, internal resistance, voltage and the like before and after aging of an electrochemical energy storage device, and the aging degree is quantified simply through a GITT test: 1. taking a fresh certain energy storage device, and measuring basic parameters such as capacity, internal resistance, average voltage and the like of the energy storage device; 2. after the energy storage device is subjected to a series of cycles or tests, basic parameters such as capacity, internal resistance, average voltage and the like are measured again; 3. And the aging degree and the failure reason are simply judged by comparing the difference between the front data and the rear data. In the prior art, the aging and failure reasons are simply judged, the actual aging condition of the anode and cathode materials under the combined action of multiple complex factors is difficult to accurately reflect, and the problem of inaccurate evaluation exists. Therefore, developing a new technical method capable of more accurately evaluating the aging state of the energy storage device becomes a key problem of the present invention. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a novel testing method for an electrochemical energy storage device, the invention adopts the combination of the three electrodes and the GITT technology to analyze the aging and failure phenomena of the energy storage device, and is simple, convenient and efficient. The two technologies are combined to deeply analyze the evolution rules of electrode material structures, interface characteristics and dynamic parameters in the aging process of the battery, so that the attenuation source is positioned. The "macroscopic capacity fade" of the cell aging is converted into a quantitative analysis of the "microscopic electrode/interface changes" by "accurate potentiometric measurement" and "kinetic parameter separation". By comparing the balance potential, polarization voltage, ion diffusion coefficient and other parameters before and after aging, the aging cause can be clarified. Support is provided for improvements in electrochemical energy storage devices and optimization of usage strategies. In order to achieve the above purpose, the technical scheme adopted by the invention is as follows: The application firstly provides a testing method for an electrochemical energy storage device, which is characterized in that step 1, a copper wire is introduced as a reference electrode in the manufacturing process of the electrochemical energy storage device; step 2, connecting a reference electrode with a cathode of a charge-discharge device, connecting an anode of an energy storage device with the anode of the charge-discharge device, running a constant-curren