CN112993213A - Calculation method of lithium supplement capacity of pre-lithiation of negative electrode and application of calculation method - Google Patents

Calculation method of lithium supplement capacity of pre-lithiation of negative electrode and application of calculation method Download PDF

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CN112993213A
CN112993213A CN202110264375.9A CN202110264375A CN112993213A CN 112993213 A CN112993213 A CN 112993213A CN 202110264375 A CN202110264375 A CN 202110264375A CN 112993213 A CN112993213 A CN 112993213A
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lithium
negative electrode
capacity
area
supplement
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杨少博
涂健
胡海波
朱登伟
徐雄文
王志斌
闫鹏
张奇
洪娟
瞿登宏
邵偲灿
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Hunan Lifang New Energy Science and Technology Co Ltd
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
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    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
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    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
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    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
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    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
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Abstract

The invention provides a method for calculating the lithium supplement capacity of the pre-lithiation of a negative electrode and application thereof, and the method can accurately calculate the lithium supplement capacity required by the negative electrode through the calculation of a formula, so that the actual lithium removal capacity per unit area of the positive electrode in the circulation process is equal to the lithium removal capacity which can be received per unit area of the positive electrode, the capacity of the positive electrode can be fully exerted, the degree of the pre-lithiation of the negative electrode is accurately grasped, the active lithium of the positive electrode consumed in the first charging and discharging process is supplemented, and the capacity density and the energy density of a lithium ion battery are improved.

Description

Calculation method of lithium supplement capacity of pre-lithiation of negative electrode and application of calculation method
Technical Field
The invention relates to the field of lithium batteries, in particular to a method for calculating the lithium supplement capacity of a pre-lithiation cathode and application thereof.
Background
With the continuous update of polymer lithium ion battery materials and the continuous improvement of battery design and production process levels, the improvement of battery capacity density and energy density becomes a bottleneck which is difficult to break through. In the process of charging and discharging the battery for the first time, the polymer lithium ion consumes certain positive active lithium due to SEI film formation and other side reactions on the surface of a graphite negative electrode, so that the first coulombic efficiency is reduced, and the irreversible loss of the battery capacity is caused, and particularly, the consumption of the polymer lithium ion on the active lithium is more obvious with the use of negative electrode materials such as a silicon negative electrode, a silicon carbon negative electrode and the like, and reaches 15-35%.
The pre-lithiation of the negative electrode can compensate active lithium ions consumed in the first charge-discharge process through the supplemented lithium, so that the first coulombic efficiency, the capacity density and the energy density of the battery and the like are improved. At present, the lithium foil lithium supplement mode is mainly used: lithium foil lithium supplement is a main measure for lithium supplement of a negative electrode, and a composite negative electrode piece is obtained by mainly compounding metal lithium foil on the surface of the negative electrode and is assembled into a battery, and pre-lithiation of the negative electrode is realized through a self-discharge principle. However, the following problems still exist in this lithium supplement method: the accuracy degree of lithium supplement and prelithiation of the negative electrode and the uniformity of prelithiation are difficult to control; the effect of supplementing lithium is not obvious on improving the first coulombic efficiency, and the improvement on the capacity density and the energy density of the battery is limited; and excessive lithium supplement can cause the formation of a metal lithium plating layer on the negative electrode, cause the problems of lithium precipitation and the like, and influence the performance of the battery. Based on this, reasonable lithium supplement amount and uniform pre-lithiation are the key of lithium supplement of the negative electrode.
Chinese patent application (CN112067672A) discloses a method for testing specific capacity of pre-lithiated lithium powder and its application, comprising: (1) mixing inert lithium powder, a binder, a conductive agent and an organic solvent to form lithium powder slurry; (2) transferring the lithium powder slurry onto a current collector, drying and rolling to obtain a working electrode; (3) calculating according to the weight of the working electrode, the weight of the current collector and the proportion of the inert lithium powder so as to obtain the lithium powder load on the current collector; (4) assembling the working electrode and the inert metal foil into a button cell; (5) taking a working electrode as a positive electrode and an inert metal foil as a negative electrode, and adopting a charging process step so as to deposit lithium in the working electrode on the inert metal foil; (6) and calculating the effective specific capacity of the inert lithium powder according to the electric quantity obtained in the charging step and the lithium powder loading capacity. However, this patent document only discloses a method for calculating the actual gram capacity of the lithium powder additive, which is to test the actual gram capacity of the lithium powder under the influence of various environments and processes during the actual production, so as to achieve the accurate addition amount, but does not disclose how to calculate the addition amount, and how much should be added specifically.
In view of the above, the present invention provides a method for calculating the lithium supplement capacity of the pre-lithiation of the negative electrode to solve the above problems.
Disclosure of Invention
One of the objects of the present invention is: the method for calculating the lithium supplement capacity of the pre-lithiation of the negative electrode is provided, and the problem that the accuracy degree of the lithium supplement capacity of the pre-lithiation of the negative electrode is difficult to calculate at present is solved.
In order to achieve the purpose, the invention adopts the following technical scheme:
a method for calculating the lithium supplement capacity of the pre-lithiation of a negative electrode comprises the following steps:
1) testing the first charge-discharge capacity of the anode material and the cathode material, and calculating to obtain the first charge capacity C of the cathode in unit areaCharger 1And first discharge capacity CPut 1And a first charge capacity C of the positive electrode per unit areaCharger 2And first discharge capacity CPut 2；
2) Calculating the lithium supplement capacity C required by the unit area positive plate, wherein the lithium supplement capacity C is the difference C between the first charge and discharge capacity of the unit area negative electrode1-difference C in first charge-discharge capacity per unit area of positive electrode2(ii) a Wherein the difference C between the first charge and discharge capacities of the negative electrode per unit area1Negative electrode initial charge capacity CCharger 1Negative first discharge capacity per unit area CPut 1(ii) a The difference C between the first charge and discharge capacity of the positive electrode per unit area2Positive electrode first charge capacity C per unit areaCharger 2First discharge capacity of positive electrode per unit area CPut 2；
3) Calculating the proportion kappa of the lithium supplement area to the area of the positive plate according to the lithium supplement capacity C required by the positive plate in unit area obtained in the step 2), wherein the calculation formula is as follows:
Figure BDA0002971532160000031
wherein 3860 is the theoretical specific capacity of lithium, and the unit is mAh/g; rho is the density of lithium in g/cm3(ii) a Delta is the thickness of the lithium foil in cm.
The unit area of the anode can receive the lithium release capacity as the first discharge capacity of the unit area of the anode before the cycle process after lithium supplement, and the actual lithium release capacity of the unit area of the anode in the cycle process is the sum of the first charge capacity of the unit area of the anode and the capacity provided by the lithium supplement minus the first charge-discharge loss capacity of the cathode. According to the invention, through reasonable lithium supplement amount calculation, the lithium supplement amount required by the negative electrode can be accurately calculated, so that the actual lithium release capacity per unit area of the positive electrode in the circulation process is equal to the lithium release capacity which can be received per unit area of the positive electrode, the capacity of the positive electrode can be fully exerted, the degree of lithium supplement and prelithiation of the negative electrode can be accurately mastered, the active lithium of the positive electrode consumed in the first charging and discharging process is supplemented, and the capacity density and the energy density of the lithium ion battery are improved.
Preferably, the lithium foil is at least one of pure metal lithium foil, lithium block, lithium sheet and lithium alloy. The lithium alloy may be a lithium magnesium alloy, a lithium copper alloy, a lithium iron alloy, an aluminum lithium alloy, or a lithium silver alloy.
Preferably, the thickness of the lithium foil is 1 μm to 50 μm. Specifically, the thickness of the lithium foil includes, but is not limited to, 1-5 μm, 5-10 μm, 10-15 μm, 15-20 μm, 20-25 μm, 25-30 μm, 30-35 μm, 35-40 μm, 40-45 μm, or 5-50 μm. When the thickness of the lithium foil is too thick, the diffusion speed of lithium ions in the negative electrode is limited, the concentration distribution of the lithium ions is uneven, and the structure of the positive electrode material is easily damaged.
Preferably, the negative electrode material comprises at least one of artificial graphite, natural graphite, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon-based composite materials, silicon-based materials, silicon-based composite materials, mesocarbon microbeads, tin-based materials, lithium titanate or other metals capable of forming an alloy with lithium. Wherein, the silicon-based material can be one or more of simple substance silicon, silicon-oxygen compound, silicon-carbon compound and silicon alloy; the tin-based material can be one or more selected from simple substance tin, tin oxide compound and tin alloy.
And the positive electrode material may be of a chemical formula including but not limited to LiaNixCoyMzO2-bNb(wherein a is more than or equal to 0.95 and less than or equal to 1.2, x>0, y is more than or equal to 0, z is more than or equal to 0, and x + y + z is 1,0 is more than or equal to b and less than or equal to 1, M is selected from one or more of Mn and Al, N is selected from one or more of F, P and S), and the positive electrode active material can also be selected from one or more of LiCoO (lithium LiCoO), but not limited to2、LiNiO2、LiVO2、LiCrO2、LiMn2O4、LiCoMnO4、Li2NiMn3O8、LiNi0.5Mn1.5O4、LiCoPO4、LiMnPO4、LiFePO4、LiNiPO4、LiCoFSO4、CuS2、FeS2、MoS2、NiS、TiS2And the like. The positive electrode active material may be further modified, and the method of modifying the positive electrode active material is known to those skilled in the art, for example, the positive electrode active material may be modified by coating, doping, and the like, and the material used in the modification may be one or a combination of more of Al, B, P, Zr, Si, Ti, Ge, Sn, Mg, Ce, W, and the like.
The invention also aims to provide a preparation method of the pre-lithiation composite negative plate, which comprises the following steps:
1) calculating the proportion kappa of the lithium supplement area to the area of the positive plate according to the calculation method of the lithium supplement capacity of the pre-lithiation of the negative electrode, and then obtaining the area of the lithium supplement lithium foil required by the single-sided positive plate according to the design area of the positive plate;
2) and cutting the lithium foil, and compounding the lithium foil to the surface of the negative plate by adopting a grid type lithium supplement method to obtain the pre-lithiation composite negative plate.
Preferably, in the step 2), the lithium foil is cut into a plurality of lithium foil small pieces, and the lithium foil small pieces are equidistantly compounded on the surface of the negative electrode piece to obtain the pre-lithiation composite negative electrode piece.
Preferably, in step 2), the lithium foil is cut into 2n pieces with equal areas, and the 2n pieces are equidistantly compounded on the surface of the negative electrode piece, wherein n is a positive integer.
Preferably, the number of the lithium foil pieces is any one of 4, 6, 8, 10, 12, 14, 16, 18 and 20.
The invention also aims to provide the composite negative electrode sheet prepared by the preparation method of the prelithiation composite negative electrode sheet.
The invention also provides a lithium ion battery, which comprises a positive plate, a negative plate and a separation film arranged between the positive plate and the negative plate, wherein the negative plate is the composite negative plate.
Compared with the prior art, the invention has the beneficial effects that:
1) the invention utilizes the formula to calculate, can accurately calculate the lithium supplementing quantity required by the negative electrode, ensures that the actual lithium releasing capacity per unit area of the positive electrode is equal to the lithium releasing capacity which can be received per unit area of the positive electrode in the circulation process, can fully exert the capacity of the positive electrode at the moment, realizes the accurate grasp of the lithium supplementing and pre-lithiation degree of the negative electrode, supplements the positive active lithium consumed in the first charging and discharging process, and improves the capacity density and the energy density of the lithium ion battery.
2) In addition, the invention also provides a pre-lithiation composite negative plate, wherein the composite negative plate adopts a grid method to compound a lithium supplement material and a negative material, and is cut into a plurality of lithium foil small pieces with the same area which can be uniformly compounded on the surface of a negative electrode, so that the diffusion speed of lithium ions in the negative electrode is similar, and the damage of the positive electrode structure caused by over-lithiation phenomenon due to uneven lithium ion concentration distribution is avoided.
Drawings
Fig. 1 is a schematic structural view of a prelithiation composite negative electrode sheet according to example 4 of the present invention.
Fig. 2 is a schematic structural diagram of a prelithiation composite negative electrode sheet according to example 5 of the present invention.
Fig. 3 is a schematic structural view of a prelithiation composite negative electrode sheet according to example 6 of the present invention.
Fig. 4 is a schematic structural view of the prelithiated composite negative electrode sheet of comparative example 1 according to the present invention.
FIG. 5 is a schematic view showing the arrangement of the reference electrode in comparative example 1 of the present invention.
FIG. 6 is a schematic view of a charge/discharge model of a lithium supplement cell according to the present invention.
In the figure: 1-positive plate; 2-negative pole piece; 3-lithium foil.
Detailed Description
In order to make the technical solutions and advantages of the present invention clearer, the present invention and its advantages will be described in further detail below with reference to the following detailed description and the accompanying drawings, but the embodiments of the present invention are not limited thereto.
Example 1
A method for calculating the lithium supplement capacity of the pre-lithiation of a negative electrode comprises the following steps:
1) testing the first charge-discharge capacity of the anode material and the cathode material, and calculating to obtain the first charge capacity C of the cathode in unit areaCharger 1And first discharge capacity CPut 1And a first charge capacity C of the positive electrode per unit areaCharger 2And first discharge capacity CPut 2；
2) Calculating the lithium supplement capacity C required by the unit area positive plate 1, wherein the lithium supplement capacity C is the difference C between the first charge and discharge capacity of the unit area negative electrode1-difference C in first charge-discharge capacity per unit area of positive electrode2(ii) a Wherein the difference C between the first charge and discharge capacities of the negative electrode per unit area1Negative electrode initial charge capacity CCharger 1Negative first discharge capacity per unit area CPut 1(ii) a The difference C between the first charge and discharge capacity of the positive electrode per unit area2Positive electrode first charge capacity C per unit areaCharger 2First discharge capacity of positive electrode per unit area CPut 2；
3) Calculating the proportion kappa of the lithium supplement area to the area of the positive plate 1 according to the lithium supplement capacity C required by the positive plate 1 in unit area obtained in the step 2), wherein the calculation formula is as follows:
Figure BDA0002971532160000061
wherein 3860 is the theoretical specific capacity of lithium, and the unit is mAh/g; rho is the density of lithium in g/cm3(ii) a δ is the thickness of the lithium foil 3 in cm.
Further, the lithium foil 3 is at least one of pure lithium foil, lithium block, lithium sheet, and lithium alloy. The lithium alloy may be a lithium magnesium alloy, a lithium copper alloy, a lithium iron alloy, an aluminum lithium alloy, or a lithium silver alloy.
Further, the lithium foil 3 has a thickness of 1 μm to 50 μm. Specifically, the thickness of the lithium foil 3 includes, but is not limited to, 1 to 5 μm, 5 to 10 μm, 10 to 15 μm, 15 to 20 μm, 20 to 25 μm, 25 to 30 μm, 30 to 35 μm, 35 to 40 μm, 40 to 45 μm, or 5 to 50 μm. When the thickness of the lithium foil 3 is too thick, the diffusion rate of lithium ions in the negative electrode is limited, the concentration distribution of the lithium ions is uneven, and the structure of the positive electrode material is easily damaged, so that in practical application, the lithium foil 3 can be as thin as possible, and lithium supplement is facilitated.
Further, the negative electrode material comprises at least one of artificial graphite, natural graphite, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon-based composite materials, silicon-based materials, silicon-based composite materials, mesocarbon microspheres, tin-based materials, lithium titanate or other metals capable of forming alloys with lithium, and the like.
Example 2
A preparation method of a pre-lithiation composite negative plate comprises the following steps:
1) calculating the proportion kappa of the lithium supplement area to the area of the positive plate 1 according to the calculation method of the lithium supplement capacity of the pre-lithiation of the negative electrode in the embodiment 1, and then obtaining the area of the lithium supplement lithium foil 3 required by the single-sided positive plate 1 according to the design area of the positive plate 1;
2) and cutting the lithium foil 3, and compounding the lithium foil 3 to the surface of the negative plate 2 by adopting a grid type lithium supplement method to obtain the pre-lithiation composite negative plate 2.
Further, in the step 2), the lithium foil 3 is cut into a plurality of lithium foil 3 small pieces, and the lithium foil 3 small pieces are equidistantly combined on the surface of the negative electrode piece 2, so that the pre-lithiation composite negative electrode piece 2 is obtained.
Further, in step 2), the lithium foil 3 is cut into 2n pieces with equal areas, and the 2n pieces are equidistantly compounded on the surface of the negative electrode piece 2, wherein n is a positive integer.
Further, the lithium foil 3 is cut into any one of 4, 6, 8, 10, 12, 14, 16, 18 and 20 pieces.
Example 3
A composite negative electrode sheet prepared by the method for preparing a pre-lithiated composite negative electrode sheet described in example 2.
Example 4
A lithium ion battery comprises a positive plate 1, a negative plate 2 and an isolating membrane arranged between the positive plate 1 and the negative plate 2, wherein the negative plate 2 is the composite negative plate 2 in embodiment 3.
The specific preparation method of the lithium ion battery comprises the following steps:
1) preparing a positive plate;
preparation of positive electrode active material slurry: mixing lithium iron phosphate, a conductive agent SuperP and a binder polyvinylidene fluoride according to the weight ratio of 96.7, 1.7 and 1.6, adding N-methylpyrrolidone (NMP), and stirring under the action of a vacuum stirrer until the system is uniform to obtain anode active material slurry with the solid content of 59%.
Positive plate 1: taking a positive current collector, dividing the positive current collector into a pole piece main body area and a pole lug area, dividing the pole lug area into a connection area and a pole lug main body area, and connecting the pole lug main body area with the pole piece main body area through the connection area; coating the positive active material slurry on at least one surface of the pole piece main body area, and drying at 85 ℃ to obtain a positive active material layer; vacuum drying for 24 hours at 60 ℃ in a drying environment to obtain a positive plate 1; the surface density of the positive electrode sheet 1 was 0.0182g/cm2The area of the pole piece is 4.2cm x 5.15 cm.
2) Preparing a negative plate;
preparation of negative active material slurry: mixing the negative active material artificial graphite, the conductive agent SuperP, the thickening agent carboxymethylcellulose sodium (CMC) and the binder Styrene Butadiene Rubber (SBR) according to the weight ratio of 95.7:1.7:1:1.6, adding deionized water, and obtaining negative active substance slurry with the solid content of 54% under the action of a vacuum stirrer.
Preparation of the negative electrode sheet 2: taking a negative current collector, dividing the negative current collector into a pole piece main body area and a pole lug area, dividing the pole lug area into a connection area and a pole lug main body area, and connecting the pole lug main body area with the pole piece main body area through the connection area; coating the negative active material slurry on two surfaces of the pole piece main body area, and drying at 85 ℃ to obtain a negative active material layer; vacuum drying for 24 hours at 60 ℃ in a drying environment to obtain the negative plate 2, wherein the surface density of the negative plate 2 is 0.0086g/cm2The area of the pole piece is 4.5cm x 5.45 cm.
3) The preparation method of the pre-lithiation composite negative plate comprises the following steps:
firstly, respectively taking the positive plate 1 and the negative plate 2 to manufacture the button cell, and testing to obtain the first charge-discharge specific capacity and the first coulombic efficiency of the positive and negative electrodes, wherein the first charge-discharge specific capacity and the first coulombic efficiency are respectively as the following table 1:
TABLE 1
Figure BDA0002971532160000081
Then the first charge capacity C of the positive electrode per unit area can be obtained by calculating the surface densityCharger 2Is 2.82mAh/cm2First discharge capacity CPut 2Is 2.76mAh/cm2First charge capacity of negative electrode per unit area CCharger 1Is 3.05mAh/cm2First discharge capacity CPut 1Is 2.88mAh/cm2；
And (3) calculating the lithium supplement capacity C required by the positive plate 1 in unit area according to a formula: lithium supplement capacity C is the difference C between the first charge and discharge capacity of the negative electrode per unit area1-difference C in first charge-discharge capacity per unit area of positive electrode2And calculating to obtain C ═ C1-C2＝0.12mAh/cm2；
Namely, the lithium supplement capacity required by the unit area of the anode is 0.12mAh/cm2；
Selecting a metal pure lithium foil with the thickness of 5 mu m for supplementing lithium to the negative electrode, wherein the density of the metal lithium is 0.53g/cm3If the ratio κ of the lithium supplement area to the positive electrode area is:
Figure BDA0002971532160000091
the lithium supplement area required by the single-sided negative electrode is 2.53cm2And the lithium supplement capacity is 4.3 percent of the positive electrode capacity, and the lithium supplement capacity is divided into 8 pieces with equal areas and is evenly and equidistantly compounded on the surface of the negative electrode to obtain a negative electrode composite lithium composite negative electrode piece 2, which can be shown in figure 1.
4) Preparing a separation film;
a commercial polypropylene film with the thickness of 12 mu m is taken as a separation film and dried for 24 hours in vacuum at the temperature of 60 ℃ in a drying environment. The separator may also be any material suitable for use in lithium ion battery separators in the art, and may be, for example, one or more combinations including, but not limited to, polyethylene, polyvinylidene fluoride, aramid, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, natural fiber, and the like.
5) Assembling the positive plate 1, the composite negative plate 2 and the isolating membrane into a lithium ion battery cell through a laminated battery manufacturing process;
6) and baking, injecting liquid, standing and forming to obtain the cathode pre-lithiation lithium ion battery.
Example 5
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2In this embodiment, the area is 2.53cm2And the lithium foil 3 with the thickness of 5 mu m is divided into 4 pieces with equal area and is evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode composite lithium composite negative electrode piece 2, which can be shown in figure 2.
The rest is the same as embodiment 4, and the description is omitted here.
Example 6
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2In this embodiment, the area is 2.53cm2The lithium foil 3 with the thickness of 5 μm is divided into 6 pieces with equal area and is evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode composite lithium composite negative electrode piece 2, which can be shown in figure 3.
The rest is the same as embodiment 4, and the description is omitted here.
Example 7
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2In this embodiment, the area is 2.53cm2And the lithium foil 3 with the thickness of 5 mu m is divided into 10 pieces with equal area and evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode compound lithium compound negative electrode piece 2.
The rest is the same as embodiment 4, and the description is omitted here.
Example 8
Different from the embodiment 4The preparation method of the lithiation composite negative plate 2 obtains the lithium supplement area required by the single-sided negative electrode by calculation to be 2.53cm2In this embodiment, the area is 2.53cm2And the lithium foil 3 with the thickness of 5 mu m is divided into 12 pieces with equal area and is evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode compound lithium compound negative electrode piece 2.
The rest is the same as embodiment 4, and the description is omitted here.
Example 9
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2When the lithium supplement capacity is 4.3 percent of the positive electrode capacity and is increased to 10 percent of the positive electrode capacity, the required lithium supplement area is 5.88cm2Then the area is 5.88cm2And the lithium foil 3 with the thickness of 5 mu m is divided into 4 pieces with equal area and is evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode compound lithium compound negative electrode piece 2.
The rest is the same as embodiment 4, and the description is omitted here.
Example 10
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2When the lithium supplement capacity is 4.3 percent of the positive electrode capacity and is increased to 10 percent of the positive electrode capacity, the required lithium supplement area is 5.88cm2Then the area is 5.88cm2And the lithium foil 3 with the thickness of 5 mu m is divided into 8 pieces with equal area and evenly and equidistantly compounded on the surface of the negative electrode to obtain the negative electrode compound lithium compound negative electrode piece 2.
The rest is the same as embodiment 4, and the description is omitted here.
Comparative example 1
Different from the embodiment 4, the method for preparing the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2In this embodiment, the area is 2.53cm2And a lithium foil 3 with a thickness of 5 μm is integrally laminated on the surface of the negative electrode to obtain a negative electrode composite lithium negative electrode sheet 2, as shown in fig. 4.
The rest is the same as embodiment 4, and the description is omitted here.
Comparative example 2
Different from the embodiment 9, the preparation method of the pre-lithiation composite negative plate 2 is used for obtaining the lithium supplement area of 2.53cm needed by the single-sided negative electrode through calculation2In this embodiment, the lithium supplement capacity is increased to 10% of the positive electrode capacity, and the required lithium supplement area is 5.88cm2The area is 5.88cm2And the metal lithium foil with the thickness of 5 mu m is integrally compounded on the surface of the negative pole piece to obtain the negative pole composite lithium negative pole piece 2.
The rest is the same as embodiment 9, and the description is omitted here.
The lithium ion batteries obtained in the above examples 4 to 10 and comparative examples 1 to 2 were subjected to performance tests, and the test results are shown in tables 2 to 3.
TABLE 2
Specific capacity for first charge (mAh/g) Specific capacity of first discharge (mAh/g) First coulombic efficiency (%)
Example 4 161.83 154.60 95.53
Example 5 164.99 152.86 92.6
Example 6 164.58 154.05 93.6
Example 7 162.36 155.13 95.55
Example 8 161.94 154.75 95.56
Example 9 163.54 146.56 89.62
Example 10 162.97 147.02 90.21
Comparative example 1 162.39 147.90 91.08
Comparative example 2 161.26 141.62 87.8
TABLE 3
Figure BDA0002971532160000121
In addition, voltage value tests are also performed on the lithium ion batteries obtained in examples 4 to 10 and comparative examples 1 to 2, and voltage values of lithium ions at different distances in the negative electrode diffusion process after lithium supplement are detected by using a reference electrode, as shown in fig. 5, and the detection results are shown in table 4. Wherein, the reference electrodes 1-3 are sequentially arranged far away from the lithium supplement center.
TABLE 4
Figure BDA0002971532160000122
The test results show that the lithium supplementing capacity is obtained by calculation through the calculation formula of the invention for lithium supplementation, the first discharge capacity of the anode is close to the test result of the anode power failure, the first coulombic efficiency of the lithium ion battery is effectively improved, the capacity of the anode can be basically and completely exerted by the calculation formula of the invention, and the problem that the accuracy degree of the current lithium supplementing capacity of the cathode pre-lithiation is difficult to calculate is solved.
In addition, it can be seen from the above test results that when lithium is supplemented by using a lithium foil, when the first charge-discharge efficiency of the negative electrode material is high and the lithium supplementation of the entire surface of the negative electrode plate cannot be achieved, a local lithium supplementation mode must be selected, and the uniformity of lithium supplementation at this time becomes a main factor influencing the performance of the pre-lithiation battery. Through the above examples and comparative examples, it is found that the diffusion speed of lithium ions in the negative electrode is limited, a significant potential difference exists between the negative electrodes at different distances from the lithium supplement central region, the lithium ions are not uniformly distributed in the negative electrode, and the closer the lithium supplement central region is, the higher the lithium intercalation concentration is, the lower the negative electrode potential is. And (3) obtaining the area of the required lithium supplement according to calculation, compounding the area of the required lithium supplement area on the surface of the negative pole piece in a large area, and finding that the contact edge of the lithium foil and the negative pole piece in the negative pole lithium supplement area presents gray specks after disassembly although the performance of the battery is improved to a certain extent. After the lithium foil is compounded on the surface of the negative plate, an edge effect exists in the process of embedding the metal lithium into the negative material, namely the edge of the metal lithium foil in contact with the graphite has the highest lithium embedding activity, and the metal lithium at the edge preferentially reacts and is embedded into the negative material, so that the lithium ion concentration at the contact edge of the lithium foil and the negative plate in the negative lithium supplementing region is the highest in the pre-lithiation process, and the lithium ions are unevenly diffused, so that more lithium ions are extracted from the edge region with high lithium ion concentration in the discharging process in the circulating process, the corresponding positive electrode region is over-lithiated, and the positive electrode structure in the region is damaged, and the iron is dissolved out.
In addition, it can be seen from the comparison of examples 4 to 8 with comparative example 1 that the smaller the lithium foil is equally divided, the better the effect is produced. The smaller the equal division is, the more the divided blocks are, and the equal distance is arranged on the surface of the negative plate, so that the lithium ion is more favorably and uniformly diffused and distributed, and the optimal lithium supplementing effect is obtained. Under the same lithium supplementing area, the more corresponding blocks are better, but under the influence of an actual process, the more blocks are more, the more operation difficulty is higher, and therefore the lithium foil can be preferably equally divided into 6-10 blocks.
In addition, as can be seen from the comparison between examples 4 to 5, 9 to 10 and comparative examples 1 to 2, when the theoretical deintercalable lithium capacity per unit area of the positive electrode in the battery cycle process after lithium supplementation exceeds the calculated acceptable deintercalable lithium capacity, the capacity of the positive electrode cannot be fully exerted, and the destruction of the positive electrode structure and the iron elution are accelerated. This is because when the lithium supplement is excessive, because the supplemented lithium exceeds the active lithium consumed in the first formation process, the negative electrode is in a certain lithium intercalation state before formation, which results in that when the positive electrode starts to delithiate during formation, the potential of the negative electrode is lower than that of the negative electrode when the lithium is not supplemented (as the black point in fig. 6 is the negative electrode potential when the positive electrode of the lithium supplement cell is delithiated), when the cut-off voltage is reached, the active lithium of the actual positive electrode is not completely delithiated, when the positive electrode is fully intercalated with lithium during discharge after formation, the discharge cut-off voltage is not reached because the negative electrode potential is lower, at this time, under the condition of external voltage and current, the negative electrode is forcedly delithiated, the positive electrode is forcedly intercalated with lithium, the negative electrode voltage is increased, the positive electrode voltage is decreased, the potential difference between the positive electrode and the negative electrode is decreased, and the discharge cut-off voltage is reached, so that the positive electrode structure is damaged, the, the discharge capacity is low, the consumption of the anode and the cathode is accelerated, and the performance of the battery is reduced.
Therefore, in the actual lithium supplement calculation, the lithium supplement capacity calculated by the formula of the invention is used for performing negative electrode lithium supplement, the lithium supplement capacity calculation accuracy degree is high, and the supplemented lithium amount basically meets the positive active lithium consumed in the first charge-discharge process, so that the capacity of the positive electrode can be fully exerted, and the capacity density and the energy density of the lithium ion battery are improved.
Variations and modifications to the above-described embodiments may also occur to those skilled in the art, which fall within the scope of the invention as disclosed and taught herein. Therefore, the present invention is not limited to the above-mentioned embodiments, and any obvious improvement, replacement or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention. Furthermore, although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims (10)

1. A method for calculating the lithium supplement capacity of the pre-lithiation of a negative electrode is characterized by comprising the following steps of:
1) testing the first charge-discharge capacity of the anode material and the cathode material, and calculating to obtain the first charge capacity C of the cathode in unit areaCharger 1And first discharge capacity CPut 1And a first charge capacity C of the positive electrode per unit areaCharger 2And first discharge capacity CPut 2；
2) Calculating the lithium supplement capacity C required by the unit area positive plate, wherein the lithium supplement capacity C is the difference C between the first charge and discharge capacity of the unit area negative electrode1-difference C in first charge-discharge capacity per unit area of positive electrode2(ii) a Wherein the difference C between the first charge and discharge capacities of the negative electrode per unit area1Negative electrode initial charge capacity CCharger 1Negative first discharge capacity per unit area CPut 1(ii) a The difference C between the first charge and discharge capacity of the positive electrode per unit area2Is a unitArea positive electrode first charge capacity CCharger 2First discharge capacity of positive electrode per unit area CPut 2；
3) Calculating the proportion kappa of the lithium supplement area to the area of the positive plate according to the lithium supplement capacity C required by the positive plate in unit area obtained in the step 2), wherein the calculation formula is as follows:
Figure FDA0002971532150000011
wherein 3860 is the theoretical specific capacity of lithium, and the unit is mAh/g; rho is the density of lithium in g/cm3(ii) a Delta is the thickness of the lithium foil in cm.
2. The method for calculating the lithium supplement capacity of the pre-lithiation of the negative electrode, according to claim 1, wherein the lithium foil is at least one of a pure metal lithium foil, a lithium block, a lithium sheet and a lithium alloy.
3. The method for calculating the lithium supplement capacity of the negative electrode prelithiation according to claim 1 or 2, wherein the thickness of the lithium foil is 1 μm to 50 μm.
4. The method for calculating the pre-lithiation lithium-supplementing capacity of the negative electrode according to claim 1, wherein the negative electrode material comprises at least one of artificial graphite, natural graphite, single-walled carbon nanotubes, multi-walled carbon nanotubes, carbon-based composite materials, silicon-based materials, silicon-based composite materials, mesocarbon microbeads, tin-based materials, lithium titanate, or other metals capable of forming an alloy with lithium.
5. The preparation method of the pre-lithiation composite negative plate is characterized by comprising the following steps of:
1) calculating the proportion kappa of the lithium supplement area to the area of the positive plate according to the calculation method of the lithium supplement capacity of the pre-lithiation of the negative electrode of any one of claims 1 to 4, and then obtaining the area of the lithium supplement lithium foil required by the single-sided positive plate according to the design area of the positive plate;
2) and cutting the lithium foil, and compounding the lithium foil to the surface of the negative plate by adopting a grid type lithium supplement method to obtain the pre-lithiation composite negative plate.
6. The method for preparing the pre-lithiated composite negative electrode sheet according to claim 5, wherein in the step 2), the lithium foil is cut into a plurality of small lithium foil pieces, and the small lithium foil pieces are equidistantly compounded on the surface of the negative electrode sheet to obtain the pre-lithiated composite negative electrode sheet.
7. The method for preparing the pre-lithiated composite negative electrode sheet according to claim 6, wherein in the step 2), the lithium foil is cut into 2n sheets with equal areas, and the 2n sheets are equidistantly compounded on the surface of the negative electrode sheet, wherein n is a positive integer.
8. The method for preparing the prelithiation composite negative electrode sheet according to any one of claim 7, wherein the number of sheets cut from the lithium foil is any one of 4, 6, 8, 10, 12, 14, 16, 18 and 20.
9. A composite negative electrode sheet prepared by the method for preparing a pre-lithiated composite negative electrode sheet according to any one of claims 5 to 8.
10. A lithium ion battery comprising a positive plate, a negative plate and a separator film spaced between the positive plate and the negative plate, wherein the negative plate is the composite negative plate of claim 9.
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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113659221A (en) * 2021-08-18 2021-11-16 东莞塔菲尔新能源科技有限公司 Secondary battery and application thereof
CN117129888A (en) * 2023-03-03 2023-11-28 荣耀终端有限公司 Method for determining lithium supplementing amount of negative electrode, verification method, battery and terminal device
CN117169748A (en) * 2023-10-19 2023-12-05 荣耀终端有限公司 Detection method for gram capacity of lithium-supplementing electrode slice
WO2024002355A1 (en) * 2022-07-01 2024-01-04 宁德新能源科技有限公司 Electrochemical device and preparation method therefor, and electronic device
CN118173920A (en) * 2024-05-14 2024-06-11 宁德时代新能源科技股份有限公司 Lithium supplementing efficiency determining method, device, apparatus, storage medium, and program product

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102610861A (en) * 2012-03-07 2012-07-25 宁德新能源科技有限公司 Method for preparing lithium ion battery
US20120295155A1 (en) * 2011-05-16 2012-11-22 Haixia Deng Silicon oxide based high capacity anode materials for lithium ion batteries
US20160126543A1 (en) * 2014-11-03 2016-05-05 Naoki Ota Pre-Lithiation of Electrode Materials in a Semi-Solid Electrode
CN106229158A (en) * 2016-07-27 2016-12-14 中航锂电（洛阳）有限公司 The preparation method of a kind of composite negative plate and composite negative plate, lithium-ion capacitor
CN107658496A (en) * 2017-09-29 2018-02-02 北京卫蓝新能源科技有限公司 A kind of secondary cell and preparation method thereof
CN109980180A (en) * 2019-03-26 2019-07-05 天津市捷威动力工业有限公司 Cathode pole piece and preparation method thereof, soft bag lithium ionic cell and preparation method thereof
CN111384405A (en) * 2018-12-28 2020-07-07 宁德时代新能源科技股份有限公司 Electrode assembly and lithium ion battery

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120295155A1 (en) * 2011-05-16 2012-11-22 Haixia Deng Silicon oxide based high capacity anode materials for lithium ion batteries
CN102610861A (en) * 2012-03-07 2012-07-25 宁德新能源科技有限公司 Method for preparing lithium ion battery
US20160126543A1 (en) * 2014-11-03 2016-05-05 Naoki Ota Pre-Lithiation of Electrode Materials in a Semi-Solid Electrode
CN106229158A (en) * 2016-07-27 2016-12-14 中航锂电（洛阳）有限公司 The preparation method of a kind of composite negative plate and composite negative plate, lithium-ion capacitor
CN107658496A (en) * 2017-09-29 2018-02-02 北京卫蓝新能源科技有限公司 A kind of secondary cell and preparation method thereof
CN111384405A (en) * 2018-12-28 2020-07-07 宁德时代新能源科技股份有限公司 Electrode assembly and lithium ion battery
CN109980180A (en) * 2019-03-26 2019-07-05 天津市捷威动力工业有限公司 Cathode pole piece and preparation method thereof, soft bag lithium ionic cell and preparation method thereof

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113659221A (en) * 2021-08-18 2021-11-16 东莞塔菲尔新能源科技有限公司 Secondary battery and application thereof
WO2024002355A1 (en) * 2022-07-01 2024-01-04 宁德新能源科技有限公司 Electrochemical device and preparation method therefor, and electronic device
CN117129888A (en) * 2023-03-03 2023-11-28 荣耀终端有限公司 Method for determining lithium supplementing amount of negative electrode, verification method, battery and terminal device
CN117169748A (en) * 2023-10-19 2023-12-05 荣耀终端有限公司 Detection method for gram capacity of lithium-supplementing electrode slice
CN118173920A (en) * 2024-05-14 2024-06-11 宁德时代新能源科技股份有限公司 Lithium supplementing efficiency determining method, device, apparatus, storage medium, and program product

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