CN112086613A - Method for optimizing tabletting pressure in preparation process of lithium battery electrode pole piece - Google Patents

Abstract

The present application discloses a method for optimizing the pressing pressure during the preparation of a lithium battery electrode pole piece, and a lithium battery electrode pole piece and a lithium battery prepared by using the method. The optimization method in this application includes: establishing a corresponding relationship between the tableting pressure and the compaction density based on the tableting pressure values and the compaction density values of the plurality of test pole pieces; The performance value and the compaction density value of the test pole pieces contained in multiple test lithium batteries respectively, establish the corresponding relationship between electrical properties and compaction density; based on the corresponding relationship between electrical properties and compaction density, determine the maximum The optimum compaction density value corresponding to the electrical property value is determined, and based on the corresponding relationship between the compaction pressure and the compaction density, the optimum compaction pressure value corresponding to the optimum compaction density value is determined. The present application can determine the optimal pressing pressure of the lithium battery electrode sheet through a simple test method, thereby providing a basis for obtaining a lithium battery with superior electrical performance.

Description

Optimization method of pressing pressure during preparation of lithium battery electrode sheet

technical field

The present application relates to the technical field of lithium ion batteries, and in particular, to a method for optimizing the pressing pressure during the preparation of lithium battery electrode pole pieces, and a lithium battery electrode pole piece and a lithium battery prepared by using the method.

technical background

Lithium-ion batteries have the advantages of high voltage, high capacity, long life, good safety and environmental protection and are widely used in electronic products, new energy vehicles, power generation and energy storage systems and other fields. Performance puts forward higher requirements. Lithium batteries are mainly composed of positive and negative electrodes, separators, and electrolytes.

During the production of battery electrode sheets, the tableting pressure directly affects the compaction density, which in turn affects the gram capacity, cycle performance, and charge-discharge efficiency of the battery. Most of the patents disclosed so far are methods for improving or measuring the compaction density of lithium battery materials, and rarely involve methods for exploring the optimal compression pressure of positive and negative electrode sheets.

SUMMARY OF THE INVENTION

The purpose of the present application is to provide a method for optimizing the pressing pressure during the preparation of lithium battery electrode plates and the lithium battery electrode plates and lithium batteries prepared by using the method. The optimization method of the present application can determine the lithium battery electrode plates. The optimal tableting pressure can provide a basis for obtaining lithium batteries with superior electrical performance.

In order to solve the above-mentioned technical problems, one aspect of the present application discloses a method for optimizing the pressing pressure in the preparation process of the electrode pole piece of a lithium battery, including:

Based on the tabletting pressure values and the compaction density values of a plurality of test pole pieces, a corresponding relationship between the tabletting pressure and the compaction density is established, wherein the areas of the plurality of test pole pieces are the same, and the tabletting pressure The value is the pressure value when the test pole piece is pressed vertically;

Based on the measured electrical property values of the plurality of test lithium batteries and the compaction density values of the test pole pieces respectively included in the plurality of test lithium batteries, establishing a correspondence between the electrical properties and the compaction density;

Based on the corresponding relationship between the electrical properties and the compacted density, determine the optimal compacted density value corresponding to the maximum electrical property value, and determine the optimal compacted density value based on the corresponding relationship between the pressing pressure and the compacted density. The optimal tableting pressure value corresponding to the optimal compaction density value.

It can be understood that the test lithium battery can use the test pole piece as the positive pole and the metal lithium piece as the negative pole. The test electrode can also be used as the negative electrode, and the corresponding lithium battery positive electrode material can be selected as the positive electrode for testing.

Another aspect of the present application discloses an electrode sheet for a lithium battery, and the pressing pressure of the electrode sheet is determined by the method for optimizing the pressing pressure in the preparation process of the electrode sheet for a lithium battery mentioned in the present application. Determined optimal tableting pressure value.

Another aspect of the application discloses a lithium battery, and the positive electrode or the negative electrode of the lithium battery is the electrode plate disclosed in another aspect of the application, wherein the pressing pressure of the electrode plate is the value mentioned in the application. The optimal tableting pressure value determined by the optimization method of the tableting pressure during the preparation of the obtained lithium battery electrode sheet.

The method for optimizing the pressing pressure during the preparation of lithium battery electrode sheets of the present application is simple to operate, and the conditions are easy to control, and is suitable for the optimization of process parameters before industrial production. The tableting mechanism consumes energy, thereby reducing production costs.

Description of drawings

FIG. 1 is a schematic flow chart of a method for optimizing the pressing pressure of a lithium battery electrode plate proposed by the application.

FIG. 2 shows the corresponding relationship between the compaction density and the pressing pressure of the tested silicon carbon pole piece in the embodiment of the application.

FIG. 3 is a relationship curve between the compaction density and the gram capacity of the tested silicon carbon pole piece in the embodiment of the present application.

FIG. 4 is a relationship curve between the compaction density of the tested silicon carbon pole piece and the Coulomb efficiency of the first cycle in the embodiment of the present application.

FIG. 5 is a schematic flowchart of a method for optimizing the pressing pressure of a lithium battery electrode plate proposed by the application.

Detailed ways

Illustrative embodiments of the present application include, but are not limited to, a method for optimizing the pressing pressure during the preparation of a lithium battery electrode sheet, and a lithium battery electrode sheet and a lithium battery prepared using the method.

This application will describe various aspects of the illustrative embodiments using terms commonly employed by those skilled in the art to convey the substance of their work to others skilled in the art. However, it will be apparent to those skilled in the art that some alternative embodiments may be practiced using parts of the described aspects. For purposes of explanation, specific numbers, materials, and configurations are set forth in order to provide a thorough understanding of the illustrative embodiments. However, it will be apparent to those skilled in the art that alternative embodiments may be practiced without the specific details. In other instances, well-known features have been omitted or simplified in order not to obscure the illustrative embodiments.

In order to make the objectives, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the accompanying drawings.

According to some embodiments of the present application, a method for optimizing the pressing pressure in the preparation process of the electrode pole piece of a lithium battery is disclosed. In this method, the electrode pole piece is a silicon carbon pole piece, which is often used as a negative electrode of a lithium battery. It can be understood that the idea of the present application is also applicable to electrode pole pieces of other materials, which may be positive pole pieces or negative pole pieces. For example, graphite pole pieces or lithium titanate pole pieces are often used as the negative electrode of lithium batteries, and lithium iron phosphate pole pieces, nickel cobalt lithium manganate pole pieces, lithium cobalt oxide pole pieces, lithium manganate pole pieces are often used as positive pole pieces of lithium batteries. Pole pieces, etc.

Specifically, referring to FIG. 1, the optimization method of the pressing pressure in the preparation process of the silicon carbon negative electrode pole piece of the lithium battery in the present application includes:

(1) Use different tableting pressures to prepare several test silicon carbon pole pieces with the same area and different compaction densities, and establish a relationship curve (100) between tableting pressure and compaction density, including:

S11 prepares a uniform silicon carbon electrode slurry, which is uniformly coated on the current collector copper foil and baked and dried. Specifically, firstly, the negative electrode active material (silicon carbon material), the conductive agent acetylene black, the thickener CMC (tetrafluoroethylene), and the binder SBR (styrene-butadiene rubber) were mixed in a mass ratio of 85:5:4:6, After adding solvent deionized water, stirring uniformly for a certain period of time under the action of a centrifugal mixer, the prepared silicon carbon electrode slurry was uniformly coated on the current collector copper foil, and dried in a vacuum oven at 80 °C for 12 hours.

S12 The current collector copper foil coated with the electrode slurry is cut into several primary silicon carbon electrode pieces (ie, primary electrode pieces) with equal areas.

In S13, by selecting the primary silicon carbon pole pieces with the same mass after cutting, and selecting the test carbon silicon pole pieces (that is, the test pole pieces) with the same areal density, wherein, the areal density of the test silicon carbon pole piece = (the total test silicon carbon pole piece Weight - collector copper foil weight) ÷ pole piece area. Specifically, several silicon carbon pole pieces of equal area were weighed one by one, and several silicon carbon pole pieces with the same mass were selected as the research object.

S14 Select different pressing pressure values within a certain pressure range to press the test silicon carbon pole piece vertically, and measure the total thickness of the test silicon carbon pole piece after pressing and the thickness of the current collector copper foil in the pole piece;

S15 calculates the compaction density of several test silicon carbon pole pieces according to the area density and thickness of several test silicon carbon pole pieces, wherein, the compaction density of the test silicon carbon pole piece = the areal density of the test silicon carbon pole piece ÷ the test The thickness of the silicon carbon pole piece (the total thickness of the test silicon carbon pole piece - the thickness of the current collector copper foil);

S16 establishes a relationship curve between tableting pressure and compaction density.

(2) Several test coin cells (ie, test lithium batteries) are prepared by using several test silicon carbon pole pieces as positive electrodes and metal lithium sheets as negative electrodes respectively (102).

Specifically, several tests were prepared in a vacuum glove box using several test silicon carbon electrode sheets prepared by the above method as positive electrodes, the same lithium metal sheets as negative electrodes, and the same electrolyte, electrode gaskets and separators. Button battery, the obtained test button battery model is one or more of CR2016, CR2025, CR2032, CR1620 and CR1632.

(3) Test and count the gram capacity (104) of several test coin cells prepared.

In a specific solution, the gram capacity can be counted by performing several charge-discharge cycle tests on several test button batteries prepared above.

As a preferred embodiment, a 10-cycle charge-discharge cycle test is performed on several test button batteries prepared above, specifically including:

Charge and discharge several test button batteries at a rate of 0.1C at room temperature, with a discharge termination voltage of 0.005V and a charge cutoff voltage of 2V, for a total of 10 cycles, and then calculate the gram capacity of several test button batteries according to the test results. In this way, sufficiently reliable gram capacity data can be obtained in a relatively short experimental time.

(4) According to the gram capacity corresponding to several test button batteries and the compaction density of the test silicon carbon pole piece, a relationship curve between the grams capacity and the compaction density is established (106).

(5) According to the relationship curve between gram capacity and compaction density, find the optimal compaction density value corresponding to the maximum gram capacity value, and substitute the optimal compaction density value into the relationship curve between tableting pressure and compaction density, and find The optimal tableting pressure value corresponding to the optimal compaction density value (108).

According to some embodiments of the present application, another method for optimizing the tableting pressure during the preparation of lithium battery electrode sheets is disclosed. In this method, the electrode pole piece is a silicon carbon pole piece, which is often used as a negative electrode of a lithium battery. It can be understood that the idea of the present application is also applicable to electrode pole pieces of other materials, which may be positive pole pieces or negative pole pieces. For example, graphite pole pieces or lithium titanate pole pieces are often used as the negative electrode of lithium batteries, and lithium iron phosphate pole pieces, nickel cobalt lithium manganate pole pieces, lithium cobalt oxide pole pieces, lithium manganate pole pieces are often used as positive pole pieces of lithium batteries. Pole pieces, etc.

Specifically, referring to FIG. 5 , the optimization method of the pressing pressure in the preparation process of the silicon carbon negative electrode pole piece of the lithium battery includes:

(1) Use different tableting pressures to prepare several test silicon carbon pole pieces with the same area and different compaction densities, and establish a relationship curve (500) between tableting pressure and compaction density, including:

S11 prepares a uniform silicon carbon electrode slurry, which is uniformly coated on the current collector copper foil and baked and dried. Specifically, firstly, the negative electrode active material (silicon carbon material), the conductive agent acetylene black, the thickener CMC (tetrafluoroethylene), and the binder SBR (styrene-butadiene rubber) were mixed in a mass ratio of 85:5:4:6, After adding solvent deionized water, stirring uniformly for a certain period of time under the action of a centrifugal mixer, the prepared silicon carbon electrode slurry was uniformly coated on the current collector copper foil, and dried in a vacuum oven at 80 °C for 12 hours.

S12 The current collector copper foil coated with the electrode slurry is cut into several primary silicon carbon electrode pieces (ie, primary electrode pieces) with equal areas.

In S13, by selecting the primary silicon carbon pole pieces with the same mass after cutting, and selecting the test carbon silicon pole pieces (that is, the test pole pieces) with the same areal density, wherein, the areal density of the test silicon carbon pole piece = (the total test silicon carbon pole piece Weight - collector copper foil weight) ÷ pole piece area. Specifically, several silicon carbon pole pieces of equal area were weighed one by one, and several silicon carbon pole pieces with the same mass were selected as the research object.

S14 Select different pressing pressure values within a certain pressure range to press the test silicon carbon pole piece vertically, and measure the total thickness of the test silicon carbon pole piece after pressing and the thickness of the current collector copper foil in the pole piece;

S15 calculates the compaction density of several test silicon carbon pole pieces according to the area density and thickness of several test silicon carbon pole pieces, wherein, the compaction density of the test silicon carbon pole piece = the areal density of the test silicon carbon pole piece ÷ the test The thickness of the silicon carbon pole piece (the total thickness of the test silicon carbon pole piece - the thickness of the current collector copper foil);

S16 establishes a relationship curve between tableting pressure and compaction density.

(2) A number of test coin cells (ie, test lithium batteries) are prepared by using several test silicon carbon pole pieces as positive electrodes and metal lithium sheets as negative electrodes respectively (502).

Specifically, several tests were prepared in a vacuum glove box using several test silicon carbon electrode sheets prepared by the above method as positive electrodes, the same lithium metal sheets as negative electrodes, and the same electrolyte, electrode gaskets and separators. Button battery, the obtained test button battery model is one or more of CR2016, CR2025, CR2032, CR1620 and CR1632.

(3) Test and count the first-cycle Coulomb efficiencies of several prepared test coin cells (504).

In a specific solution, the cyclic charge-discharge measurement can also be performed on several test button batteries prepared above, and then the first cycle Coulomb efficiency value can be obtained based on the first-time charge-discharge measurement result.

As a preferred embodiment, a 10-cycle charge-discharge cycle test is performed on several test button batteries prepared above, specifically including:

Several test button cells were charged and discharged at a rate of 0.1C at room temperature, the discharge termination voltage was 0.005V, and the charging cutoff voltage was 2V, for a total of 10 cycles, and then the first cycle Coulomb efficiency was determined according to the test results of the first cycle of charge and discharge.

(4) According to the first cycle Coulomb efficiency corresponding to several test button cells and the compaction density of the test silicon carbon pole piece, a relationship curve between the first cycle Coulomb efficiency and the compaction density is established (506).

(5) According to the relationship between the Coulomb efficiency and the compaction density in the first circle, find the optimal compaction density value corresponding to the maximum Coulomb efficiency value in the first circle, and substitute the optimal compaction density value into the relationship between the tableting pressure and the compaction density. The relationship curve is used to find the optimal tableting pressure value corresponding to the optimal compaction density value (508).

The following is a specific embodiment according to the above-mentioned optimization method, as follows:

A commercial silicon carbon negative electrode material with a nominal capacity of 600mAh/g was selected as the negative electrode active material, and it was mixed with a conductive agent acetylene black, a thickener CMC, and a binder SBR in a mass ratio of 85:5:4:6, and a solvent was added. Deionized water was stirred evenly under the action of a centrifugal mixer to obtain electrode slurry. The silicon carbon electrode slurry was uniformly coated on the current collector copper foil, and then placed in a vacuum oven to dry at 80 °C for 12 hours. Divide the dried pole pieces into several (multiple) circular primary silicon carbon pole pieces with a radius of 0.7 cm and an area of 1.54 cm ² , and weigh the weight and collection of the cut primary silicon carbon pole pieces respectively. For the weight of the fluid copper foil, several primary carbon-silicon pole pieces with a total weight of 26.00±0.05mg were selected as the test carbon-silicon pole pieces, and the areal density of the several test silicon-carbon pole pieces was calculated to be 7.1 mg/cm ² .

To debug the pressure value of the tablet pressing mechanism, press the above test carbon silicon electrodes with the pressures of 4MPa, 8MPa, 8MPa, 10MPa, 11MPa, 12MPa, 14MPa and 17MPa respectively. The thickness of the fluid copper foil can be calculated, and the thicknesses of the tested silicon carbon pole pieces corresponding to different pressing pressures are: 61μm, 56μm, 53μm, 51μm, 49μm, 48μm, 46μm, 44μm, and then calculate that the different pressing pressure The compacted densities of the pressure-pressed silicon carbon electrodes were 1.17 g/cm ³ , 1.27 g/cm ³ , 1.34 g/cm ³ , 1.40 g/cm ³ , 1.45 g/cm ³ , 1.48, 1.55 g/cm ³ , 1.62g/cm ³ , according to which, the relationship curve between the tableting pressure and the compaction density can be established, as shown in Figure 2.

Several test silicon carbon electrode sheets with different compaction densities were used as the positive electrode, metal lithium sheets were used as the negative electrode, and the same electrolyte, separator and electrode gasket were used to complete the assembly and preparation of the CR2016 button battery in a vacuum glove box.

Using the blue battery test system (LANHE CT2001A, 5V, 20mA), the above button battery was tested for 10 cycles of charge and discharge. The single cycle was discharged at a constant current of 0.1C, and the discharge termination voltage was 0.005V. 0.1C constant current charging, cut-off voltage is 2V, stand for 2 minutes.

The resulting data of gram capacity, first-round Coulomb efficiency (referred to as first-round efficiency), compaction density and tableting pressure are shown in the following table:

Tablet pressure value, MPa Compaction density value, g/cm³ Gram capacity value, mAh/g First lap efficiency value, % 4 1.17 572 76.95% 8 1.27 584 77.45% 9 1.34 588 77.97% 10 1.40 594 78.18% 11 1.45 590 78.03% 12 1.48 583 77.87% 14 1.55 579 77.65% 17 1.62 573 77.28%

The gram capacity was counted separately and corresponded to the compacted density, and the relationship curve between the gram capacity and the compacted density was obtained, as shown in Figure 3.

The Coulomb efficiency of the first circle is counted separately and corresponds to the compaction density, and the relationship curve between the Coulomb efficiency and the compaction density of the first circle is obtained, as shown in Figure 4.

According to the results of Figure 2 and Figure 3, it can be seen that within a certain range, the compaction density of the tested silicon carbon pole piece increases with the increase of the pressing pressure. However, the gram capacity of the test button battery increases first and then decreases with the increase of the compaction density. When the compaction density is 1.40g/cm3, the gram capacity reaches the maximum value of 594mAh/g, indicating that the test button battery has the optimal electric capacity at this time. performance, then the corresponding tableting pressure of 10MPa can be regarded as the optimal tableting pressure.

According to the results in Figure 4, it can be seen that within a certain range, the compaction density of the tested silicon carbon pole piece increases with the increase of the pressing pressure. However, the first cycle Coulomb efficiency of the test button battery increases first and then decreases with the increase of the compaction density. When the compaction density is 1.40g/cm3, the first cycle Coulomb efficiency reaches the maximum value of 78.18%, which is the same as that of the gram capacity. , that is, the corresponding tableting pressure of 10MPa can be regarded as the optimal tableting pressure.

It can be understood that although the above-mentioned embodiments of the present application show the corresponding relationship between tableting pressure and compacted density, the corresponding relationship between gram capacity and compacted density, and the relationship between the first circle Coulomb efficiency and compacted density in a curvilinear manner. However, the two can also be expressed in other ways, for example, expressed in the form of a data list, and each parameter value is obtained by calculation, which is not limited here.

The above are only preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention shall be included in the protection of the present application. within the range.

The technical solutions of the present application are further summarized in the following examples:

Embodiment 1 may include a method for optimizing the pressing pressure during the preparation of a lithium battery electrode pole piece, the method comprising:

Based on the tabletting pressure values and the compaction density values of a plurality of test pole pieces, a corresponding relationship between tabletting pressure and compaction density is established, wherein the areas of the plurality of test pole pieces are the same, and the tabletting pressure The value is the pressure value when the test pole piece is pressed vertically;

Based on the measured electrical property values of the plurality of test lithium batteries and the compaction density values of the test pole pieces respectively included in the plurality of test lithium batteries, establish a corresponding relationship between the electrical properties and the compaction density ;

Based on the corresponding relationship between the electrical properties and the compacted density, determine the optimal compacted density value corresponding to the maximum electrical property value, and determine the optimal compacted density value based on the corresponding relationship between the pressing pressure and the compacted density. The optimal tableting pressure value corresponding to the optimal compaction density value.

Embodiment 2 may include the method of Embodiment 1, optionally, the compaction density values of the plurality of pole pieces are obtained in the following manner:

Obtain multiple test pole pieces with the same pole piece area and pole piece weight;

Pressing the plurality of test pole pieces with different pressing pressures, and measuring the thickness of the plurality of test pole pieces after pressing;

According to the pole piece area, the pole piece weight, and the pole piece thickness of the plurality of test pole pieces, the compaction density of the plurality of test pole pieces is calculated.

Embodiment 3 may include the method described in Embodiment 2, and optionally, obtaining a plurality of test pole pieces with the same pole piece area and pole piece weight includes:

preparing uniform electrode slurry, and uniformly coating the prepared electrode slurry on the current collector metal foil;

baking and drying the current collector metal foil coated with the electrode slurry;

cutting the dried collector metal foil coated with the electrode slurry into a plurality of primary pole pieces with the same area;

A plurality of primary pole pieces with the same weight are selected from the plurality of primary pole pieces as the plurality of test pole pieces.

Wherein, when the electrode slurry is a negative electrode material, the metal foil is a copper foil, and when the electrode slurry is a positive electrode material, the metal foil is an aluminum foil.

Embodiment 4 may include the method described in Embodiment 3, optionally, the weight of the pole piece of the test pole piece is the total weight of the test pole piece and the weight of the current collector metal foil in the test pole piece. difference, the thickness of the pole piece of the test pole piece is the difference between the total thickness of the test pole piece and the thickness of the current collector metal foil in the test pole piece; and

The compaction density of the plurality of pole pieces is calculated by the following formula:

Compaction density = area density / pole piece thickness,

Among them, areal density = pole piece weight / pole piece area

Embodiment 5 may include the method of any one of Embodiments 1 to 4, optionally, the method of claim 1, wherein the electrical property is gram capacity, and

The gram capacity values of the plurality of test lithium batteries are obtained in the following ways:

Using the plurality of test pole pieces as the positive electrode and the lithium piece as the negative electrode, respectively, prepare a plurality of test lithium batteries;

A charge-discharge cycle test is performed on the prepared plurality of test lithium batteries, and the gram capacity values of the plurality of test lithium batteries are obtained based on the test results.

Embodiment 5 may include the method of any one of Embodiments 1 to 4, optionally, the electrical property is a first cycle Coulomb efficiency, and

The first cycle Coulomb efficiency values of the multiple test lithium batteries are obtained in the following manner:

Using the plurality of test pole pieces as the positive electrode and the lithium piece as the negative electrode, respectively, prepare a plurality of test lithium batteries;

A charge-discharge cycle test is performed on the prepared plurality of test lithium batteries, and the first cycle Coulomb efficiency values of the plurality of test lithium batteries are obtained based on the test results of the first cycle.

Embodiment 7 may include the method described in any one of Embodiments 1 to 6. Optionally, the test pole piece is any one of a silicon carbon pole piece, a graphite pole piece, or a lithium titanate pole piece.

Embodiment 8 may include the method described in any one of Embodiments 1 to 6, optionally, the test pole piece is a lithium iron phosphate pole piece, a nickel cobalt manganese oxide lithium pole piece, a lithium cobalt oxide pole piece, a manganese Any of the lithium oxide pole pieces.

Embodiment 9 may include the method of any one of Embodiments 1 to 8, optionally, the correspondence between the tableting pressure and the compaction density, the correspondence between the electrical properties and the compaction density Relationships are represented in the form of curves.

Embodiment 10 may include the method described in any one of Embodiments 1 to 9, optionally, after determining the optimal tableting pressure value corresponding to the optimal compaction density value, further comprising:

Electrode pads for lithium batteries are prepared with the tableting pressure corresponding to the optimal tableting pressure value, wherein the area and weight of the electrode pads are the same as the area and weight of the test electrode pads, respectively.

Embodiment 11 may include an electrode sheet for a lithium battery, optionally, the pressing pressure of the electrode sheet is an optimal pressure determined by the method described in any one of Embodiments 1 to 9. tablet pressure value.

Embodiment 12 may include a lithium battery. Optionally, the positive electrode or the negative electrode of the lithium battery is the electrode plate described in Embodiment 11.

In the drawings, some structural or method features may be shown in specific arrangements and/or sequences. It should be understood, however, that such specific arrangements and/or orderings may not be required. Rather, in some embodiments, the features may be arranged in a manner and/or order different from that shown in the illustrative figures. Additionally, the inclusion of structural or method features in a particular figure is not meant to imply that such features are required in all embodiments, and in some embodiments these features may not be included or may be combined with other features.

It should be noted that in the examples and specification of this patent, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply Any such actual relationship or sequence exists between these entities or operations. Moreover, the terms "comprising", "comprising" or any other variation thereof are intended to encompass non-exclusive inclusion such that a process, method, article or device comprising a list of elements includes not only those elements, but also includes not explicitly listed or other elements inherent to such a process, method, article or apparatus. Without further limitation, an element qualified by the phrase "comprising a" does not preclude the presence of additional identical elements in a process, method, article, or device that includes the element.

Although the present application has been illustrated and described with reference to certain preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and detail may be made therein without departing from the present disclosure The spirit and scope of the application.

Claims (12)

1. an optimization method of tableting pressure in a lithium battery electrode pole piece preparation process, is characterized in that, comprises: Based on the tabletting pressure values and the compaction density values of a plurality of test pole pieces, a corresponding relationship between the tabletting pressure and the compaction density is established, wherein the areas of the plurality of test pole pieces are the same, and the tabletting pressure The value is the pressure value when the test pole piece is pressed vertically; Based on the measured electrical property values of the plurality of test lithium batteries and the compaction density values of the test pole pieces respectively included in the plurality of test lithium batteries, a corresponding relationship between the electrical properties and the compaction density is established ; Based on the corresponding relationship between the electrical properties and the compacted density, determine the optimal compacted density value corresponding to the maximum electrical property value, and determine the optimal compacted density value based on the corresponding relationship between the pressing pressure and the compacted density. The optimal tableting pressure value corresponding to the optimal compaction density value. 2. The method according to claim 1, wherein the compaction density values of the plurality of pole pieces are obtained in the following manner: Obtain multiple test pole pieces with the same pole piece area and pole piece weight; Pressing the plurality of test pole pieces with different pressing pressures, and measuring the thickness of the plurality of test pole pieces after pressing; According to the pole piece area, the pole piece weight, and the pole piece thickness of the plurality of test pole pieces, the compaction density of the plurality of test pole pieces is calculated. 3. method according to claim 2, is characterized in that, obtaining the same multiple test pole piece of pole piece area and pole piece weight comprises: preparing uniform electrode slurry, and uniformly coating the prepared electrode slurry on the current collector metal foil; baking and drying the current collector metal foil coated with the electrode slurry; cutting the dried collector metal foil coated with the electrode slurry into a plurality of primary pole pieces with the same area; A plurality of primary pole pieces with the same weight are selected from the plurality of primary pole pieces as the plurality of test pole pieces. 4. The method according to claim 3, wherein the pole piece weight of the test pole piece is the difference between the total weight of the test pole piece and the weight of the current collector metal foil in the test pole piece , the thickness of the pole piece of the test pole piece is the difference between the total thickness of the test pole piece and the thickness of the current collector metal foil in the test pole piece; and The compaction density of the plurality of pole pieces is calculated by the following formula: Compaction density = area density / pole piece thickness, Wherein, areal density=pole piece weight/pole piece area. 5. The method of claim 1, wherein the electrical property is gram capacity, and The gram capacity values of the plurality of test lithium batteries are obtained in the following ways: Using the plurality of test pole pieces as the positive electrode and the lithium piece as the negative electrode, respectively, prepare a plurality of test lithium batteries; A charge-discharge cycle test is performed on the prepared plurality of test lithium batteries, and the gram capacity values of the plurality of test lithium batteries are obtained based on the test results. 6. The method of claim 1, wherein the electrical property is a first cycle Coulomb efficiency, and The first cycle Coulomb efficiency values of the multiple test lithium batteries are obtained in the following manner: Using the plurality of test pole pieces as the positive electrode and the lithium piece as the negative electrode, respectively, prepare a plurality of test lithium batteries; A charge-discharge cycle test is performed on the prepared plurality of test lithium batteries, and the first cycle Coulomb efficiency values of the plurality of test lithium batteries are obtained based on the test results of the first cycle. 7 . The method according to claim 1 , wherein the test pole piece is any one of a silicon carbon pole piece, a graphite pole piece or a lithium titanate pole piece. 8 . 8. The method according to any one of claims 1 to 6, wherein the test pole piece is a lithium iron phosphate pole piece, a nickel cobalt lithium manganate, a lithium cobalt oxide pole piece, and a lithium manganate pole piece any of the. 9. The method according to any one of claims 1 to 6, wherein the correspondence between the tableting pressure and the compaction density, and the correspondence between the electrical properties and the compaction density are all Represented in the form of a curve. 10. The method according to claim 1, wherein after determining the optimal tableting pressure value corresponding to the optimal compaction density value, the method further comprises: Electrode pads of the lithium battery are prepared with the tableting pressure corresponding to the optimum tableting pressure value, wherein the area and weight of the electrode pads are respectively the same as the area and weight of the test pads. 11. An electrode pole piece of a lithium battery, wherein the pressing force of the electrode pole piece is an optimum pressing pressure value determined by the method according to any one of claims 1 to 9 . 12 . A lithium battery, wherein the positive electrode or the negative electrode of the lithium battery is the electrode pole piece described in claim 11 .

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