CN117074451B - Method for detecting distribution state of prelithiation material in pole piece - Google Patents
Method for detecting distribution state of prelithiation material in pole piece Download PDFInfo
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- CN117074451B CN117074451B CN202311317536.1A CN202311317536A CN117074451B CN 117074451 B CN117074451 B CN 117074451B CN 202311317536 A CN202311317536 A CN 202311317536A CN 117074451 B CN117074451 B CN 117074451B
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- 239000000463 material Substances 0.000 title claims abstract description 165
- 238000009826 distribution Methods 0.000 title claims abstract description 109
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000001035 drying Methods 0.000 claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 32
- 238000001514 detection method Methods 0.000 claims abstract description 28
- 238000006243 chemical reaction Methods 0.000 claims abstract description 12
- 229910052744 lithium Inorganic materials 0.000 claims description 31
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 claims description 25
- 238000005507 spraying Methods 0.000 claims description 5
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 claims 1
- 150000004767 nitrides Chemical class 0.000 claims 1
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 description 39
- 238000006138 lithiation reaction Methods 0.000 description 22
- 238000001000 micrograph Methods 0.000 description 15
- 238000004364 calculation method Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 9
- GELKBWJHTRAYNV-UHFFFAOYSA-K lithium iron phosphate Chemical compound [Li+].[Fe+2].[O-]P([O-])([O-])=O GELKBWJHTRAYNV-UHFFFAOYSA-K 0.000 description 7
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 230000000694 effects Effects 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 238000001816 cooling Methods 0.000 description 5
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 4
- 241001085205 Prenanthella exigua Species 0.000 description 4
- XGZVUEUWXADBQD-UHFFFAOYSA-L lithium carbonate Chemical compound [Li+].[Li+].[O-]C([O-])=O XGZVUEUWXADBQD-UHFFFAOYSA-L 0.000 description 4
- 229910052808 lithium carbonate Inorganic materials 0.000 description 4
- -1 lithium nitrides Chemical class 0.000 description 4
- FUJCRWPEOMXPAD-UHFFFAOYSA-N lithium oxide Chemical compound [Li+].[Li+].[O-2] FUJCRWPEOMXPAD-UHFFFAOYSA-N 0.000 description 4
- 229910001947 lithium oxide Inorganic materials 0.000 description 4
- GLNWILHOFOBOFD-UHFFFAOYSA-N lithium sulfide Chemical compound [Li+].[Li+].[S-2] GLNWILHOFOBOFD-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 3
- JXGGISJJMPYXGJ-UHFFFAOYSA-N lithium;oxido(oxo)iron Chemical compound [Li+].[O-][Fe]=O JXGGISJJMPYXGJ-UHFFFAOYSA-N 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 229910002092 carbon dioxide Inorganic materials 0.000 description 2
- 239000001569 carbon dioxide Substances 0.000 description 2
- 230000000295 complement effect Effects 0.000 description 2
- 230000001351 cycling effect Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 239000007772 electrode material Substances 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000009827 uniform distribution Methods 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000001493 electron microscopy Methods 0.000 description 1
- IDBFBDSKYCUNPW-UHFFFAOYSA-N lithium nitride Chemical compound [Li]N([Li])[Li] IDBFBDSKYCUNPW-UHFFFAOYSA-N 0.000 description 1
- HPGPEWYJWRWDTP-UHFFFAOYSA-N lithium peroxide Chemical compound [Li+].[Li+].[O-][O-] HPGPEWYJWRWDTP-UHFFFAOYSA-N 0.000 description 1
- LBSANEJBGMCTBH-UHFFFAOYSA-N manganate Chemical compound [O-][Mn]([O-])(=O)=O LBSANEJBGMCTBH-UHFFFAOYSA-N 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000012163 sequencing technique Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/225—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion
- G01N23/2251—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material using electron or ion using incident electron beams, e.g. scanning electron microscopy [SEM]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N23/00—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00
- G01N23/22—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by measuring secondary emission from the material
- G01N23/2202—Preparing specimens therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
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- Pathology (AREA)
- Analysing Materials By The Use Of Radiation (AREA)
Abstract
The application provides a method for detecting the distribution state of a prelithiation material in a pole piece, which comprises the following steps: acquiring a first pole piece; contacting the first pole piece with water to enable the pre-lithiated material on the surface of the first pole piece to undergo an alkalization reaction so as to obtain a second pole piece; drying the second pole piece to remove water; and carrying out scanning electron microscope detection on the dried second pole piece to obtain a pre-lithiated material distribution image, wherein white bright spots in the pre-lithiated material distribution image represent the pre-lithiated material. The method for detecting the distribution state of the pre-lithiated material in the pole piece is simple and convenient, can directly distinguish the pre-lithiated material in the pole piece when the scanning electron microscope detects only by simply processing the pole piece, further determines the distribution state of the pre-lithiated material, and is quick, efficient and low in detection cost.
Description
Technical Field
The application relates to the technical field of battery pole piece detection, in particular to a method for detecting the distribution state of a prelithiation material in a pole piece.
Background
Along with the increasing demand of energy, secondary batteries are the focus of attention, and lithium ion secondary batteries are widely used in daily life of people due to the advantages of long cycle life, high and stable battery voltage, better cycle performance than other secondary batteries, capability of quick charge and discharge, higher specific capacity of batteries, lower self-discharge rate of batteries, low pollution to the environment and the like.
The new energy industry develops rapidly, and people put higher demands on the energy density and the circulation level of the battery, and the currently effective method is to add a pre-lithiation material in the pole piece, wherein the pre-lithiation material can provide additional lithium ions, complement the short plate effect caused by the first effect difference of the anode and the cathode, and can improve the energy density of the battery. And redundant lithium ions can be stored in the negative electrode, so that capacity attenuation caused by active lithium loss in the cycling process is slowed down, and the cycle life of the battery is prolonged.
The uniform distribution of the electrode material has an important influence on the performance of the battery, particularly, if the distribution is uneven, the local lithium precipitation is caused, and the battery performance is poor, but the existing method is difficult to distinguish the pre-lithiated material from other main materials when Scanning Electron Microscope (SEM) detection is adopted, because the appearance and the appearance of the pre-lithiated material are consistent with those of other common main materials, the distribution condition of the pre-lithiated material in the pole piece cannot be identified, and whether the pre-lithiated material is uniformly distributed in the pole piece cannot be known, so that a method capable of simply and effectively detecting the distribution state of the pre-lithiated material in the pole piece is needed.
Disclosure of Invention
In view of the above, the present application aims to provide a method for detecting a distribution state of a prelithiation material in a pole piece, so as to solve the above-mentioned technical problems.
The application provides a method for detecting the distribution state of a prelithiation material in a pole piece, which comprises the steps of obtaining a first pole piece; contacting the first pole piece with water to enable the pre-lithiated material on the surface of the first pole piece to undergo an alkalization reaction so as to obtain a second pole piece; drying the second pole piece to remove water; and carrying out scanning electron microscope detection on the dried second pole piece to obtain a pre-lithiated material distribution image, wherein white bright spots in the pre-lithiated material distribution image represent the pre-lithiated material.
Further, the method for detecting the distribution state of the prelithiation material in the pole piece further comprises the following steps: and calculating to obtain the distribution uniformity of the pre-lithiated material according to the white bright points in the pre-lithiated material distribution image.
Further, the calculating to obtain the distribution uniformity of the pre-lithiated material according to the white bright point in the pre-lithiated material distribution image includes: randomly acquiring a plurality of sub-region images from the pre-lithiated material distribution image; determining the number of the white bright spots in each subarea image, and calculating to obtain the maximum value, the minimum value and the average value of the number of the white bright spots in a plurality of subarea images; distribution uniformity of the prelithiated material= (maximum-minimum)/average.
Further, a plurality of the sub-region images are not overlapped at all in the pre-lithiated material distribution image, the size of the sub-region images is inversely related to the addition amount of the pre-lithiated material, and the number of the white bright points in each sub-region image is 5 to 20.
Further, the contacting the first pole piece with water includes: and spraying water on the surface of the first pole piece to react for a first preset time, or placing the first pole piece in humid air to react for a second preset time.
Further, the first preset time is 5s to 20s, the second preset time is 20h to 30h, and the relative humidity of the humid air is greater than or equal to 60%.
Further, the drying the second pole piece to remove water includes: and airing or drying the second pole piece.
Further, the drying time is 20 to 30 hours, the drying time is 2 to 5 hours, and the drying temperature is 80 ℃ or more.
Further, the scanning electron microscope detection of the dried second pole piece is performed to obtain a distribution image of the prelithiation material, which comprises the following steps: cutting the dried second pole piece according to a preset size.
Further, the pre-lithiated material includes one or more of a lithium oxide, a lithium nitride, a lithium sulfide, or a lithium metallate.
From the above, it can be seen that the present application provides a method for detecting a distribution state of a prelithiation material in a pole piece, which includes obtaining a first pole piece, contacting the first pole piece with water, and making the prelithiation material on the surface of the first pole piece undergo an alkalization reaction to obtain a second pole piece, wherein the prelithiation material has a plurality of residual lithium and compounds thereof on the surface, and reacts with water to generate lithium hydroxide; drying the second pole piece to remove water, so as to avoid influencing the subsequent scanning electron microscope detection; the dried second electrode sheet is subjected to scanning electron microscope detection to obtain an electron microscope image, and the lithium hydroxide is obviously bright white in the electron microscope image, the main material in the electrode sheet is black or gray to form clear contrast, and the lithium hydroxide is obtained after the reaction of the pre-lithiation material, so that white bright spots in the electron microscope image represent the pre-lithiation material, namely a distribution image of the pre-lithiation material, and the distribution state of the pre-lithiation material can be determined; the method for detecting the distribution state of the pre-lithiated material in the pole piece is simple and convenient, and can directly distinguish the pre-lithiated material in the pole piece during detection of the scanning electron microscope only by simply processing the pole piece, so that the distribution state of the pre-lithiated material is determined, and the method is quick and efficient and has low detection cost.
Drawings
In order to more clearly illustrate the technical solutions of the present application or related art, the drawings that are required to be used in the description of the embodiments or related art will be briefly described below, and it is apparent that the drawings in the following description are only embodiments of the present application, and other drawings may be obtained according to these drawings without inventive effort to those of ordinary skill in the art.
Fig. 1 is a schematic flow chart of detecting distribution states of prelithiation materials in a pole piece in an embodiment of the present application;
FIG. 2 is an electron microscope image of comparative example 1 of the present application;
FIG. 3 is an electron microscope image of comparative example 2 of the present application;
FIG. 4 is an image of the distribution of pre-lithiated material in example 1 of the present application;
FIG. 5 is an image of the distribution of pre-lithiated material in example 2 of the present application;
fig. 6 is an image of the distribution of the prelithiated material of example 3 of the present application.
Detailed Description
For the purposes of making the objects, technical solutions and advantages of the present application more apparent, the present application will be further described in detail below with reference to the accompanying drawings.
It should be noted that unless otherwise defined, technical or scientific terms used in the embodiments of the present application should be given the ordinary meaning as understood by one of ordinary skill in the art to which the present application belongs. The terms "first," "second," and the like, as used in embodiments of the present application, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The word "comprising" or "comprises", and the like, means that elements or items preceding the word are included in the element or item listed after the word and equivalents thereof, but does not exclude other elements or items. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate relative positional relationships, which may also be changed when the absolute position of the object to be described is changed.
Along with the increasing demand of energy, secondary batteries are the focus of attention, and lithium ion secondary batteries are widely used in daily life of people due to the advantages of long cycle life, high and stable battery voltage, better cycle performance than other secondary batteries, capability of quick charge and discharge, higher specific capacity of batteries, lower self-discharge rate of batteries, low pollution to the environment and the like.
The new energy industry develops rapidly, and people put higher demands on the energy density and the circulation level of the battery, and the currently effective method is to add a pre-lithiation material in the pole piece, wherein the pre-lithiation material can provide additional lithium ions, complement the short plate effect caused by the first effect difference of the anode and the cathode, and can improve the energy density of the battery. And redundant lithium ions can be stored in the negative electrode, so that capacity attenuation caused by active lithium loss in the cycling process is slowed down, and the cycle life of the battery is prolonged.
The uniform distribution of the electrode material has an important influence on the performance of the battery, particularly, if the distribution is uneven, the local lithium precipitation is caused, and the battery performance is poor, but the existing method is difficult to distinguish the pre-lithiated material from other main materials when Scanning Electron Microscope (SEM) detection is adopted, because the appearance and the appearance of the pre-lithiated material are consistent with those of other common main materials, the distribution condition of the pre-lithiated material in the pole piece cannot be identified, and whether the pre-lithiated material is uniformly distributed in the pole piece cannot be known, so that a method capable of simply and effectively detecting the distribution state of the pre-lithiated material in the pole piece is needed.
In the process of realizing the application, the pole piece is stored for a long time, the pre-lithiation material on the surface of the pole piece reacts with moisture, carbon dioxide and the like in the air to generate alkaline lithium hydroxide and/or lithium carbonate, the lithium hydroxide and the lithium carbonate can be obviously bright white under a scanning electron microscope, other main materials such as lithium iron phosphate are black or gray, the two main materials form clear contrast, the distribution situation of the pre-lithiation material in the initial pole piece can be directly determined by observing the distribution situation of white bright spots in an electron microscope image, the contact of the initial pole piece with water can be considered to carry out alkalization reaction, the process of converting the pre-lithiation material into lithium hydroxide is accelerated, and the distribution state of the pre-lithiation material in the pole piece can be simply and rapidly determined.
The following describes the technical solution of the present application in detail by means of specific embodiments in combination with fig. 1 to 6.
In some embodiments of the present application, a method for detecting a distribution state of a prelithiated material in a pole piece is provided, as shown in fig. 1, including the following steps:
s1, acquiring a first pole piece.
The first pole piece is obtained, the first pole piece is, for example, a battery positive electrode, a main material in the pole piece is, for example, lithium iron phosphate and the like, a pre-lithiation material in the pole piece comprises one or more of lithium oxides, lithium nitrides, lithium sulfides or lithium metal salts, the lithium oxides are, for example, lithium oxides, lithium peroxide and the like, the lithium nitrides are, for example, lithium nitrides, inert lithium nitrides and the like, the lithium sulfides are, for example, lithium sulfides and the like, and the lithium metal salts are, for example, one or more of lithium-rich nickel acid lithium, lithium-rich ferrite lithium, lithium-rich cobalt acid lithium, lithium-rich manganate and lithium-rich ternary materials, and the like, and the method is not particularly limited.
The first pole piece can be cut into strips, so that subsequent contact reaction with water is facilitated, the cutting size is for example 5cm x 1cm, and the method is not particularly limited.
S2, contacting the first pole piece with water to enable the pre-lithiated material on the surface of the first pole piece to undergo an alkalization reaction so as to obtain a second pole piece.
The first pole piece is contacted with water, so that the pre-lithiation material on the surface of the first pole piece is subjected to an alkalization reaction to obtain a second pole piece, a lot of residual lithium and compounds thereof are arranged on the surface of the pre-lithiation material, the residual lithium and the compounds thereof react with the water to generate lithium hydroxide, and the main material has higher stability and hardly reacts with the water, thereby providing a foundation for the subsequent formation of a distribution image of the pre-lithiation material.
S3, drying the second pole piece to remove water.
And drying the second pole piece to remove water, so as to avoid influencing the subsequent scanning electron microscope detection.
S4, scanning electron microscope detection is carried out on the dried second pole piece to obtain a pre-lithiated material distribution image, wherein white bright spots in the pre-lithiated material distribution image represent the pre-lithiated material.
The dried second electrode sheet is subjected to scanning electron microscope detection to obtain an electron microscope image, and the lithium hydroxide is obviously bright white in the electron microscope image, and the main material in the electrode sheet is black or gray, for example, as shown in fig. 4 to 6, so that sharp contrast is formed, and lithium hydroxide is obtained after reaction of the pre-lithiated material, so that white bright spots in the electron microscope image represent the pre-lithiated material, and the electron microscope image is a distribution image of the pre-lithiated material, so that the distribution state of the pre-lithiated material can be determined.
The method for detecting the distribution state of the pre-lithiated material in the pole piece is simple and convenient, and can directly distinguish the pre-lithiated material in the pole piece during detection of the scanning electron microscope only by simply processing the pole piece, so that the distribution state of the pre-lithiated material is determined, and the method is quick and efficient and has low detection cost.
In some embodiments, the image analysis software in the related art may be used to automatically identify white bright spots in the pre-lithiated material distribution image, for example, set an area with actual gray scale smaller than the preset gray scale as a white bright spot, and the description thereof will be omitted.
In some embodiments, the method of detecting a distribution state of a prelithiated material in a pole piece further comprises:
s5, calculating to obtain the distribution uniformity of the pre-lithiated material according to the white bright points in the pre-lithiated material distribution image.
The distribution uniformity of the pre-lithiated material can be obtained by calculation according to the number of white bright spots in the distribution image of the pre-lithiated material, so as to judge whether the pre-lithiated material is uniformly distributed in the pole piece.
In some embodiments, step S5 comprises:
s501, randomly acquiring a plurality of sub-region images from the pre-lithiated material distribution image.
Randomly acquiring a plurality of sub-region images from the pre-lithiated material distribution image, wherein the shape of the sub-region images is, for example, rectangular or circular, etc., the number of the sub-region images is 5 to 10, for example, 5, 6, 7, 8, 9 or 10, the sub-region images are not limited, the number is not limited, the calculation accuracy of distribution uniformity is reduced, the number is also prevented from being excessive, and the processing amount is increased; the plurality of sub-region images are not overlapped in the pre-lithiated material distribution image, so that the computing accidental is reduced, and the computing accuracy of the distribution uniformity is improved; the size of the sub-region image is inversely related to the addition amount of the pre-lithiation material, namely, the smaller the addition amount of the pre-lithiation material is, the larger the size of the sub-region image is, so that white bright spots are avoided in the sub-region image when the pre-lithiation material is smaller, and the calculation accuracy of the distribution uniformity is reduced; the number of white bright spots within each sub-area image may be set to 5 to 20 to ensure calculation accuracy of distribution uniformity.
S502, determining the number of the white bright spots in each sub-area image, and calculating to obtain the maximum value, the minimum value and the average value of the number of the white bright spots in the plurality of sub-area images.
And determining the number of the white bright spots in each sub-area image, wherein the white bright spots intersected with the edges of the sub-area image can be eliminated when the number is determined, and the method is not particularly limited.
And calculating to obtain a maximum value Nmax, a minimum value Nmin and an average value Navg of the number of white bright spots in the plurality of sub-area images, wherein for example, the number of the sub-area images is 5, respectively determining the number of the white bright spots in each sub-area image, then sequencing to determine the maximum value and the minimum value, and then calculating the average value of the number of the white bright spots in the 5 sub-area images, thereby providing a basis for the subsequent calculation of the distribution uniformity.
S503, the distribution uniformity of the prelithiation material= (maximum value-minimum value)/average value.
The smaller the distribution uniformity A= (Nmax-Nmin)/Navg, the smaller the A value is, which means that the fluctuation of the white bright point number in the subarea image is, and the better the distribution of the pre-lithiated material in the pole piece is.
In some embodiments, the contacting the first pole piece with water comprises:
s201, water is sprayed on the surface of the first pole piece to react for a first preset time, or the first pole piece is placed in humid air to react for a second preset time.
And water is sprayed on the surface of the first pole piece for reacting for a first preset time, wherein the first preset time is 5s to 20s, for example, 5s, 10s, 15s or 20s, and the like, the method is not particularly limited, and the water covers the surface of the first pole piece, so that the alkalization reaction of the pre-lithiation material can be rapidly realized, and lithium hydroxide is generated.
The first pole piece is placed in humid air for reaction for a second preset time, the second preset time is 20h to 30h, for example, 20h, 25h or 30h, and the like, the relative humidity of the humid air is more than or equal to 60%, for example, 60%, 70% or 80%, and the like, the relative humidity is not limited, the pre-lithiation material reacts with water in the humid air to generate lithium hydroxide, in the process, part of the lithium hydroxide reacts with carbon dioxide in the air to generate lithium carbonate, and both the lithium carbonate and the lithium hydroxide can be in bright white in the detection of a scanning electron microscope.
In some embodiments, the drying the second pole piece to remove moisture includes:
s301, airing or drying the second pole piece.
The drying time is 20h to 30h, for example, 20h, 25h or 30h, etc., and the drying time is 2h to 5h, for example, 2h, 3h, 4h or 5h, etc., and the drying temperature is 80 ℃ or higher, for example, 80 ℃, 90 ℃ or 100 ℃, etc., and the drying time is not limited.
In some embodiments, the scanning electron microscope detection of the dried second pole piece obtains a pre-lithiated material distribution image, which includes:
s400, cutting the dried second pole piece according to a preset size.
The preset size is, for example, 3mm by 3mm, and is not particularly limited, and the second pole piece is cut, so that scanning electron microscope detection is facilitated.
Comparative example 1
And obtaining a first pole piece, wherein the main material of the first pole piece is lithium iron phosphate and does not contain a pre-lithiation material.
Cutting the first pole piece into pole piece strips with the length of 5cm and the length of 1cm, spraying water on the pole piece strips, standing for 5s to obtain second pole pieces, transferring the second pole pieces into an oven, drying at the temperature of 80 ℃ for 2h, taking out the second pole pieces after cooling, cutting the second pole pieces into micro pole pieces with the length of 3mm and the length of 3mm, attaching the micro pole pieces to a sample table, and performing scanning electron microscope detection to obtain an electron microscope image, wherein the result is shown in figure 2.
Comparative example 2
And obtaining a first pole piece, wherein the main material of the first pole piece is lithium iron phosphate, and the first pole piece contains 5% of pre-lithiated material lithium-rich lithium ferrite by mass percent.
Cutting the first pole piece into pole piece strips with the length of 5cm and the length of 1cm, directly transferring the pole piece strips into an oven for drying treatment to remove moisture, wherein the drying temperature is 80 ℃, the drying time is 2 hours, taking out the pole piece strips after cooling, cutting the pole piece strips into pole pieces with the length of 3mm and the length of 3mm, attaching the pole pieces to a sample stage, and carrying out scanning electron microscope detection to obtain an electron microscope image, wherein the result is shown in figure 3.
Example 1
And obtaining a first pole piece, wherein the main material of the first pole piece is lithium iron phosphate, and the first pole piece contains 5% of pre-lithiated material lithium-rich lithium ferrite by mass percent.
Cutting the first pole piece into pole piece strips with the length of 5cm and the length of 1cm, spraying water on the pole piece strips, standing for 5 seconds to obtain second pole pieces, transferring the second pole pieces into an oven, drying at the temperature of 80 ℃ for 2 hours, cooling, taking out the second pole pieces, cutting the second pole pieces into micro pole pieces with the length of 3mm and the length of 3mm, attaching the micro pole pieces to a sample table, carrying out scanning electron microscope detection to obtain a distribution image of the prelithiation material, randomly acquiring 5 sub-area images from the distribution image of the prelithiation material, determining the number of white bright points in each sub-area image, wherein the number of white bright points in each sub-area image is 5, 6, 7 and 5, and calculating to obtain the maximum value, the minimum value and the average value of the number of white bright points in the sub-area images, wherein the distribution uniformity of the prelithiation material is= (maximum value-minimum value)/average value, and the distribution uniformity of the prelithiation material in the pole pieces is calculated to be 0.34.
Example 2
And obtaining a first pole piece, wherein the main material of the first pole piece is lithium iron phosphate, and the first pole piece contains 50% of pre-lithiated material lithium-rich lithium ferrite.
Cutting the first pole piece into pole piece strips with the length of 5cm and the length of 1cm, spraying water on the pole piece strips, standing for 5 seconds to obtain second pole pieces, transferring the second pole pieces into an oven, drying at the temperature of 80 ℃ for 2 hours, cooling, taking out the second pole pieces, cutting the second pole pieces into micro pole pieces with the length of 3mm and the length of 3mm, attaching the micro pole pieces to a sample table, carrying out scanning electron microscope detection to obtain a distribution image of the pre-lithiated material, randomly acquiring 5 sub-area images from the distribution image of the pre-lithiated material, determining the number of white bright points in each sub-area image, namely 5, 6, 5 and 13, calculating the maximum value, the minimum value and the average value of the number of white bright points in the sub-area images, namely 13, 5 and 7, respectively, and calculating the distribution uniformity= (maximum value-minimum value)/average value of the pre-lithiated material in the distribution image to obtain the distribution image of the pre-lithiated material, wherein the distribution uniformity of the pre-lithiated material is 1.14.
Example 3
And obtaining a first pole piece, wherein the main material of the first pole piece is lithium iron phosphate and contains 3% of pre-lithiated material lithium-rich lithium nickelate by mass.
Cutting the first pole piece into pole piece strips with the length of 5cm and the length of 1cm, placing the pole piece strips in humid air with the relative humidity of 80% for 24 hours to obtain second pole pieces, transferring the second pole pieces into an oven for drying treatment to remove moisture, wherein the drying temperature is 80 ℃, the drying time is 2 hours, taking out the second pole pieces after cooling, cutting the second pole pieces into micro pole pieces with the length of 3mm and the length of 3mm, attaching the micro pole pieces to a sample table, carrying out scanning electron microscope detection to obtain a distribution image of the pre-lithiated material, randomly acquiring 5 sub-area images from the distribution image of the pre-lithiated material, determining the number of white bright spots in each sub-area image, wherein the number of white bright spots in each sub-area image is 8, 7, 6 and 6, and calculating to obtain the maximum value, the minimum value and the average value of the number of white bright spots in the sub-area images, wherein the maximum value, the minimum value and the average value are 8, 6 and 6.6, respectively, and the uniformity of the pre-lithiated material is= (maximum value-minimum value)/average value, and the uniformity of the pre-lithiated material in the pole piece is calculated to be 0.3.
Table 1 comparative and example distribution uniformity calculation results table
As is clear from comparative examples 1 and 2, the electrode sheet to which the pre-lithiated material was not added was contacted with water and then subjected to scanning electron microscopy, and the obtained electron microscopy was black or gray, with no distinct white area.
As can be seen from comparative example 2 and fig. 3, the electrode sheet added with the pre-lithiated material is directly subjected to scanning electron microscope detection, the obtained electron microscope image is black or gray, no obvious white area exists, the appearance and the appearance of the pre-lithiated material are consistent with those of the electrode sheet main material, and the pre-lithiated material cannot be distinguished through the electron microscope image.
As can be seen from examples 1 to 3 and fig. 4 to 6, the electrode sheet added with the pre-lithiated material is contacted with water and then subjected to scanning electron microscope detection, and the obtained electron microscope main body is black or gray, but there is an obvious white bright point, the white bright point represents the pre-lithiated material, and the black or gray region represents the electrode sheet main material.
According to comparative examples 1 and 2 and the electron microscope images of examples 1 to 3, the distribution uniformity of the pre-lithiated material in the pole piece was calculated, since the images of comparative examples 1 and 2 did not form white bright spots, the distribution uniformity could not be calculated, whereas the images of examples 1 to 3 formed white bright spots, the distribution uniformity could be calculated according to the number of white bright spots, the calculation results were shown in table 1, wherein the distribution uniformity calculated in example 2 was the largest, representing the most uneven distribution of the pre-lithiated material, and it was also apparent from fig. 5 that the difference in the distribution density of the white bright spots was large, and the distribution effect of the pre-lithiated material in the pole piece was poor; the distribution uniformity calculated in the embodiment 1 and the embodiment 3 is smaller, which means that the distribution of the pre-lithiated material is uniform, and it is obvious from fig. 4 and 6 that the distribution density of the white bright spots is not greatly different, the distribution effect of the pre-lithiated material in the pole piece is good, the calculation result corresponds to the actual performance one by one, and the accuracy of the calculation method for the distribution uniformity is higher.
Those of ordinary skill in the art will appreciate that: the discussion of any of the embodiments above is merely exemplary and is not intended to suggest that the scope of the application (including the claims) is limited to these examples; the technical features of the above embodiments or in the different embodiments may also be combined within the idea of the present application, the steps may be implemented in any order, and there are many other variations of the different aspects of the embodiments of the present application as described above, which are not provided in detail for the sake of brevity.
In addition, where details are set forth to describe example embodiments of the present application, it will be apparent to one skilled in the art that embodiments of the present application may be practiced without, or with variation of, these details. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.
Well-known power/ground connections to other components may or may not be shown in the drawings provided to simplify the illustration and discussion, and so as not to obscure the embodiments of the present application. Furthermore, the devices may be shown in block diagram form in order to avoid obscuring the embodiments of the present application, and this also takes into account the fact that specifics with respect to implementation of such block diagram devices are highly dependent upon the platform on which the embodiments of the present application are to be implemented (i.e., such specifics should be well within purview of one skilled in the art). Where specific details are set forth in order to describe example embodiments of the present application, it should be apparent to one skilled in the art that embodiments of the present application may be practiced without, or with variation of, these specific details. Accordingly, the description is to be regarded as illustrative in nature and not as restrictive.
While the present application has been described in conjunction with specific embodiments thereof, many alternatives, modifications, and variations of those embodiments will be apparent to those skilled in the art in light of the foregoing description. The present embodiments are intended to embrace all such alternatives, modifications and variances which fall within the broad scope of the appended claims. Accordingly, any omissions, modifications, equivalents, improvements and/or the like which are within the spirit and principles of the embodiments are intended to be included within the scope of the present application.
Claims (10)
1. A method of detecting a distribution of pre-lithiated material in a pole piece, comprising:
acquiring a first pole piece;
contacting the first pole piece with water to enable the pre-lithiated material on the surface of the first pole piece to undergo an alkalization reaction so as to obtain a second pole piece;
drying the second pole piece to remove water;
and carrying out scanning electron microscope detection on the dried second pole piece to obtain a pre-lithiated material distribution image, wherein white bright spots in the pre-lithiated material distribution image represent the pre-lithiated material, and black or gray areas represent the main material of the pole piece.
2. The method of detecting a distribution of prelithiated material in a pole piece of claim 1, further comprising: and calculating to obtain the distribution uniformity of the pre-lithiated material according to the white bright points in the pre-lithiated material distribution image.
3. The method of detecting a distribution state of a prelithiated material in a pole piece according to claim 2, wherein the calculating to obtain a distribution uniformity of the prelithiated material from the white bright points in the prelithiated material distribution image includes:
randomly acquiring a plurality of sub-region images from the pre-lithiated material distribution image;
determining the number of the white bright spots in each subarea image, and calculating to obtain the maximum value, the minimum value and the average value of the number of the white bright spots in a plurality of subarea images;
distribution uniformity of the prelithiated material= (maximum-minimum)/average.
4. A method of detecting the distribution of prelithiated material in a pole piece as in claim 3, wherein a plurality of said sub-region images are completely non-overlapping within said prelithiated material distribution image, the size of said sub-region images being inversely related to the amount of said prelithiated material added, the number of said white bright spots within each of said sub-region images being from 5 to 20.
5. The method of detecting a pre-lithiated material distribution state in a pole piece of claim 1, wherein said contacting the first pole piece with water comprises: and spraying water on the surface of the first pole piece to react for a first preset time, or placing the first pole piece in humid air to react for a second preset time.
6. The method of claim 5, wherein the first preset time is 5s to 20s, the second preset time is 20h to 30h, and the relative humidity of the humid air is greater than or equal to 60%.
7. The method for detecting a distribution state of a prelithiated material in a pole piece according to claim 1, wherein the drying the second pole piece to remove moisture comprises: and airing or drying the second pole piece.
8. The method of detecting a distribution of prelithiated material in a pole piece of claim 7, wherein the time of drying is 20h to 30h, the time of drying is 2h to 5h, and the temperature of drying is 80 ℃ or higher.
9. The method for detecting a distribution state of a prelithiation material in a pole piece according to claim 1, wherein the scanning electron microscope detection of the second pole piece after drying to obtain a prelithiation material distribution image comprises the following steps: cutting the dried second pole piece according to a preset size.
10. The method of detecting a distribution of a prelithiated material in a pole piece of claim 1, wherein the prelithiated material comprises one or more of an oxide of lithium, a nitride of lithium, a sulfide of lithium, or a metalloate of lithium.
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