Failure Analysis Method of Li-ion Battery Based on AC Impedance Method

A lithium-ion battery, AC impedance technology, applied in the field of lithium-ion battery failure analysis, can solve problems such as heavy workload, cumbersome analysis process, and many related parameters, and achieve the effect of evaluating life and safety

Active Publication Date: 2020-05-29
BEIHANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The above method can indeed reflect the changes of relevant parameters such as the internal resistance of the battery more accurately, thus making it possible to predict the formation of internal lithium dendrites, but the above method involves many relevant parameters, the analysis process is relatively cumbersome, and the operation workload bigger

Method used

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  • Failure Analysis Method of Li-ion Battery Based on AC Impedance Method
  • Failure Analysis Method of Li-ion Battery Based on AC Impedance Method
  • Failure Analysis Method of Li-ion Battery Based on AC Impedance Method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] When the battery is cycled at a rate of 1C, the diffusion resistance R SEI Variation curve with cycle number, such as figure 2 shown, 4.4V overcharge under R SEI The value increases rapidly with the increase of the number of cycles. In the first 30 cycles of the charge-discharge cycle, the surface layer diffusion resistance R SEI It gradually increased from 44.56Ω to 224.2Ω after 10 weeks, indicating that under the overcharge condition of 4.4V cut-off voltage, the surface structure of the material particles changed significantly, the SEI film thickened significantly with the increase of cycle number, and the film resistance increased. And cycle to 40 weeks, R SEI The value becomes 157.3Ω, a sudden decrease compared with 30 weeks, and then R SEI Continue to increase to 585.4Ω at 50 weeks.

[0028] In order to verify the prediction, for the occurrence of R SEI After the battery at the inflection point where the value begins to decrease is disassembled, observe the n...

Embodiment 2

[0030] When fixing the cathode material LiCoO 2 When the equivalent mass ratio of the negative electrode MCMB microspheres is 1.2:1, the battery is charged and discharged at different cut-off voltages of 4.4V and 4.6V. The result is as Figure 4 As shown, when the battery charging cut-off voltage is set to 4.4V, the diffusion resistance of the surface layer gradually increases from 25.67Ω to 74.04Ω after 10 weeks in the first 30 weeks of the charge-discharge cycle, indicating that the SEI film gradually increases during the cycle. thick, during subsequent cycles R S EI value decreased to 60.55Ω; and when the battery charging cut-off voltage was 4.6V, the diffusion resistance of the surface layer decreased significantly when the cycle reached 20 cycles, indicating that the impedance of the lithium-ion battery increased with the increase of the cut-off voltage in the overcharged state, but R SEI The inflection point at which the value begins to decrease occurs earlier, indic...

Embodiment 3

[0032] When the battery charging cut-off voltage is set to 4.4V, the positive electrode material LiCoO 2 The batteries with the equivalent mass ratio of 1.2:1, 1.3:1 and 1.4:1 to the negative electrode MCMB microspheres were tested. During the charging and discharging cycle of the battery, the diffusion resistance of the surface layer gradually increased (such as Figure 5 shown). When LiCoO 2 R SEI The inflection point appeared at 40 weeks; when the mass ratio was 1.4:1, R SEI The inflection point appears at 30 weeks. It shows that with the increase of the excess ratio of positive electrode materials, the problem of internal short circuit caused by lithium dendrites intensifies, and the time of internal short circuit occurs earlier.

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Abstract

The invention provides a lithium ion battery failure analysis method based on an alternating current impedance method. The safety performance of a lithium-ion battery has attracted much attention, anda negative electrode of the lithium ion battery is easily subjected to lithium evolution under the abuse condition, so that a lithium dendritic crystal is formed, and thermal runaway or even explosion of the battery is caused. According to the lithium ion battery failure analysis method based on the alternating current impedance method provided by the invention, an electrochemical alternating current impedance testing method is adopted, a relationship between an alternating current impedance spectrum signal and the internal environment of the battery is analyzed, the SEI film resistance change can be analyzed from an alternating current impedance spectrum, and therefore the state of short circuit in the dendritic crystal of the battery can be quickly and accurately predicted without damaging the battery, thereby evaluating the service life and the safety of the battery.

Description

technical field [0001] The invention relates to the field of safety detection of lithium ion batteries, in particular to an analysis method for failure of lithium ion batteries. Background technique [0002] Due to its high energy density, good cycle performance and no memory effect, lithium-ion batteries are rapidly developing in the field of consumer electronics and are the most widely used rechargeable batteries in portable electronic devices. With the development of lithium-ion battery technology, it is gradually used in electric vehicles, military and aerospace and other fields. [0003] However, lithium-ion batteries will age and fail after long-term cycling, and even pose potential safety hazards. Judging from the current research, abuse conditions such as overcharge, short circuit, collision and overheating will cause safety hazards of lithium-ion batteries, which may trigger a series of potential exothermic reactions inside lithium-ion batteries. Among them, the d...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/392G01R31/389H01M10/44
CPCH01M10/44Y02E60/10
Inventor 邢雅兰张世超李红磊吴昊
Owner BEIHANG UNIV
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