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Method for detecting lithium extraction of negative electrode of lithium ion battery

A technology of lithium-ion batteries and detection methods, which is applied in the direction of material analysis, measurement devices, and analysis materials using wave/particle radiation, which can solve problems such as battery safety threats, difficult detection, and electronic insensitivity, and achieve simple and easy Perform detection methods, avoid security problems, and the effect of simple methods

Active Publication Date: 2015-12-30
HARBIN INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The deposited lithium reacts with the electrolyte to consume active lithium, resulting in the loss of active lithium and the thickening of the SEI film on the surface, resulting in the loss of battery capacity and the reduction of battery life
The growth of lithium dendrites on the negative electrode and the formation of dead lithium can easily pierce the separator and cause a short circuit between the positive and negative electrodes of the battery, thereby causing safety issues
[0005] Because lithium metal is very active, it reacts when it comes into contact with air, and it is not sensitive to electrons, so it is difficult to detect it. It is difficult to detect lithium precipitated from the negative electrode by means of energy spectroscopy and XRD.
At present, the detection method of lithium ionization at the negative electrode of lithium-ion batteries is relatively simple, mainly through the morphology analysis after the battery is disassembled. Generally, only when a large amount of dendrites are formed on the surface of the electrode can it be observed by scanning electron microscope or optical microscope. battery safety may have been compromised

Method used

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  • Method for detecting lithium extraction of negative electrode of lithium ion battery
  • Method for detecting lithium extraction of negative electrode of lithium ion battery
  • Method for detecting lithium extraction of negative electrode of lithium ion battery

Examples

Experimental program
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Effect test

Embodiment 1

[0038] Provided in the present embodiment is to realize the detection method of lithium on the surface of lithium sheet according to the following steps:

[0039] 1. DMC solution configuration of zinc nitrate: dry zinc nitrate (dried at 110-130°C), after drying, take out 10g of zinc nitrate and dissolve it in 100mL of dimethyl carbonate (DMC) solution to form zinc nitrate of organic solutions.

[0040] 2. Reaction of lithium flakes with zinc nitrate: soak metal lithium flakes in the DMC solution of zinc nitrate, find that the surface of lithium flakes with metallic luster turns black rapidly, and after 30 minutes, the surface of lithium flakes almost all turns black, and there is no change in continuing immersion. To ensure that the reaction is complete, the soaking time used in the experiment is 1-2 hours. The scanning electron microscope test was carried out on the lithium sheet before and after immersion, and the figure 1 It can be seen that the surface of the original li...

Embodiment 2

[0042] The detection of lithium precipitation on the normal charge and discharge negative electrode and the excessive lithium intercalation negative electrode is realized according to the following steps:

[0043] 1. Preparation of MCMB (mesophase carbon microspheres) button half-battery: the ratio of MCMB electrode material is MCMB:AB:PVDF=85:5:10, and assembled into a 2025-type button battery. Among them, the research electrode is MCMB pole piece, the reference electrode is Li piece, and the electrolyte is 1mol / LLiPF 6(EC / DEC / EMC, volume ratio 1:1:1), the diaphragm is made of polypropylene. The coin cell (MCMB / Li) was formed 3 times.

[0044] 2. Carry out 1C0-1.5V charge and discharge and excessive lithium intercalation charge and discharge 3 times on the formed button battery, such as image 3 shown. image 3 The discharge curve of the medium-excessive lithium intercalation showed a plateau below 0V after discharging to 0.7mAh, which was presumed to be the deposition of ...

Embodiment 3

[0050] 1. Lithium cobalt oxide / MCMB full battery is charged and discharged 3 times at -20°C and 0.3C. Disassemble the battery in a fully discharged state, cut off part of the negative electrode and wash it 3 times in DMC to remove the residual electrolyte.

[0051] 2. Soak the negative electrode in the DMC solution of zinc chloride for 1-2 hours, take it out, and wash it with DMC for 3 times to remove the residual zinc chloride on the surface.

[0052] 3. The pole piece treated with zinc chloride is subjected to scanning electron microscope test, and it can be seen that strip-like substances are formed at a certain position on the surface. Figure 9-11 The distribution of Zn element on the surface of the middle electrode is the same as the distribution of the strip-shaped substance in the scanning electron microscope, and then it is determined that the strip-shaped substance corresponds to zinc, the product of the reaction between lithium and zinc ions, and the distribution of ...

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Abstract

The invention discloses a method for detecting lithium extraction of a negative electrode of a lithium ion battery. The method comprises the steps of 1, disassembling a to-be-detected lithium ion battery, taking out a negative electrode slice, and clearly cleaning the negative electrode slice by using an organic solvent; 2, soaking the negative electrode slice in an organic solution of metal salt Mn<+>, enabling Mn<+> and extracted lithium to be subjected to sufficient replacement reaction, taking out the negative electrode slice after the replacement reaction is completed, and then cleaning the negative electrode slice by using the organic solvent to obtain the clean negative electrode slice; 3, carrying out qualitative or quantitative analysis on a product M through an energy spectrum analyzer, X-ray diffraction, an X-ray fluorescence spectrum, or an X-ray photoelectron spectroscopy, an atomic absorption spectrum or an inductive coupling high-frequency plasma by the negative electrode slice after the replacement reaction, and further determining whether the negative electrode is in the lithium extraction or not and the relative size of the lithium extraction amount. According to the method disclosed by the invention, whether the negative electrode of the lithium ion battery has the lithium extraction or not can be accurately detected, so that the situation that the safety of the lithium ion battery is affected due to the lithium extraction of the negative electrode can be avoided, the service life of the lithium ion battery is prolonged, the safety of the lithium ion battery is increased, the operation is simple and convenient, and the detection accuracy is higher.

Description

technical field [0001] The invention belongs to the technical field of lithium-ion batteries, and relates to a detection method for analyzing the presence or absence of lithium analysis and the position of lithium analysis in a negative electrode after a lithium-ion battery is disassembled. Background technique [0002] Lithium-ion batteries have become the most promising secondary batteries due to their significant advantages such as high specific energy density, long cycle life, high operating voltage, fast charging speed, low self-discharge rate, and no memory effect. With the widespread application of lithium-ion batteries in electronic products (including mobile phones, digital cameras and laptop computers, etc.), electric vehicles and other fields, the safety of lithium-ion batteries has also received more and more attention. [0003] In the lithium-ion battery system, the negative electrode material has a great influence on the overall performance of the battery. The ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N23/00G01N23/22G01N23/223
Inventor 杜春雨刘倩倩尹鸽平左朋建程新群高云智马玉林
Owner HARBIN INST OF TECH
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