CN109742386B - Negative electrode slurry and preparation method thereof, negative electrode sheet and manufacturing method thereof, and battery - Google Patents
Negative electrode slurry and preparation method thereof, negative electrode sheet and manufacturing method thereof, and battery Download PDFInfo
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Abstract
The invention discloses a negative electrode slurry and a preparation method thereof, a negative electrode sheet and a manufacturing method thereof, and a battery, wherein the preparation method of the negative electrode slurry comprises the following steps: mixing NMP and PVDF powder to obtain a first glue solution; adding super-p into the first glue solution and stirring to obtain a second glue solution; and adding lithium titanate and graphite into the second glue solution, and stirring to obtain the cathode slurry. According to the preparation method of the negative electrode slurry, a proper amount of graphite is added in the process of preparing the lithium titanate slurry, so that the compaction density of a negative electrode piece formed by coating the slurry is improved, and the energy density and the conductivity of a battery made of the lithium titanate material are improved.
Description
Technical Field
The invention relates to the technical field of energy storage devices, in particular to negative electrode slurry and a preparation method thereof, a negative electrode sheet and a manufacturing method thereof, and a battery.
Background
Lithium ion batteries in which lithium carbonate (LTO) is used as the negative electrode have a poor lithium ion concentration, and the operating voltage of lithium ion batteries is related to the concentration of lithium ion intercalation compounds and lithium ions constituting the electrodes. During charging, the negative electrode is in a lithium-rich state, the positive electrode is in a lithium-poor state, meanwhile, compensation of electrons is supplied to the negative electrode from an external circuit, charge balance of the negative electrode of the battery is guaranteed, and the charge balance is opposite during discharging. Under normal charge and discharge conditions, lithium ions are intercalated and deintercalated between layers of the carbon material having a layered structure, and generally only change the interlayer spacing without damaging the crystal structure.
The Lithium Titanate (LTO) material has higher potential (1.5V Vs Li +/Li), so that dendritic lithium is difficult to form on the LTO surface of the battery within a normal voltage range, the possibility of short circuit caused by lithium dendritic crystals inside the battery is avoided, and the safety performance of the battery is improved. LTO has a very large diffusion coefficient of 2X 108cm2The high diffusion coefficient makes it possess faster and higher cyclic charge and discharge capacity. The LTO with the spinel structure has certain accommodation capacity for lithium ions, generally speaking, one lithium titanate can accommodate 3 lithium ions, so that the insertion and the extraction of the lithium ions in the charging and discharging process have almost no influence on the structure of the LTO material, and the lithium titanate has the characteristic of long cycle life as a zero-strain material. In addition, the LTO material also has the advantage of small attenuation of discharging efficiency in high and low temperature environments. However, the theoretical specific capacity of the LTO material is only 175mAh/g, the energy density of the prepared battery is low, meanwhile, the electronic conductivity of the LTO material is poor, and the specific energy of the material is difficult to be fully exerted, so that the LTO cannot meet the requirement of the high-energy-density battery, and further the wide application of the lithium titanate battery is limited.
Disclosure of Invention
In view of this, the invention provides a negative electrode slurry and a preparation method thereof, a negative electrode sheet and a manufacturing method thereof, and a battery, so as to relieve agglomeration of silicon powder in a negative electrode material and improve energy density, rate capability and cycle stability of the battery.
In order to achieve the purpose, the invention adopts the following technical scheme:
a first aspect of the present invention provides a method for preparing anode slurry, including:
mixing NMP and PVDF powder to obtain a first glue solution;
adding super-p into the first glue solution and stirring to obtain a second glue solution;
and adding lithium titanate and graphite into the second glue solution, and stirring to obtain the cathode slurry.
Optionally, the NMP and the PVDF powder are mixed to obtain a first glue solution, specifically:
stirring the NMP for the first time, and meanwhile, uniformly adding the PVDF powder to obtain a primary mixed glue solution;
sequentially carrying out secondary stirring and tertiary stirring on the primary mixed glue solution;
wherein the time of the second stirring is less than the time of the third stirring and is more than or equal to the time of the first stirring; the rotating speed of the primary stirring and the rotating speed of the tertiary stirring are both less than or equal to the rotating speed of the secondary stirring.
Alternatively, the primary stirring, the secondary stirring, and the tertiary stirring are all performed at the same temperature.
Optionally, super-p is added into the first glue solution and stirred to obtain a second glue solution, which specifically comprises:
and adding the super-p into the first glue solution at a constant speed within a first preset time, and stirring in a manner of increasing the rotating speed to obtain a second glue solution.
Optionally, in the stirring at the same time in a manner of increasing the rotating speed, the rotating speed is increased from 300 to 600 to 3000 to 6000 rmp.
Optionally, adding lithium titanate and graphite into the second glue solution, and stirring to obtain a negative electrode slurry, specifically:
alternately and uniformly adding the lithium titanate and the graphite into the second glue solution within the time range of 30-90 minutes, and stirring at a first rotating speed to obtain a mixed glue solution;
stirring the mixed glue solution at a second rotating speed for 15-60 minutes to obtain the cathode slurry;
wherein the first rotational speed is less than or the second rotational speed.
Optionally, the first rotation speed is 300rmp to 5000 rmp; the second rotating speed is 5000-8000 rmp.
Optionally, in the negative electrode slurry, the ratio of active material: the super-p: the PVDF is prepared from (90-96) by mass: (2-5): (2-5), wherein the active material comprises the lithium titanate and the graphite; the mass ratio of the lithium titanate to the graphite is (4-6): (4-6);
and/or the viscosity of the negative electrode slurry is 3500mpa · s to 5500mpa · s;
and/or the fineness of the negative electrode slurry is 10-30 mu m;
and/or the solid content of the negative electrode slurry is 30-50%.
A second aspect of the present invention provides a method of manufacturing a negative electrode sheet, including:
preparing a negative electrode slurry by using any one of the preparation methods;
vacuumizing the negative electrode slurry;
coating the negative electrode slurry on a negative electrode current collector and drying to obtain a coated pole piece;
and compacting the coating pole piece to obtain the negative pole piece.
Optionally, during the step of coating the negative electrode slurry on the negative electrode current collector and drying, the coating speed is 5-12 inches/min.
Optionally, during the step of coating the negative electrode slurry on the negative electrode current collector and drying, the drying temperature is increased in a two-stage temperature increasing manner.
OptionallyThe surface density of the coating pole piece is 55g/cm2～90g/cm2。
Optionally, the compacted density of the negative electrode sheet is 1.6g/cm3～2.3g/cm3。
The third aspect of the invention provides an anode slurry prepared by the preparation method of any one of the above.
A fourth aspect of the invention provides a negative electrode sheet manufactured by the manufacturing method of any one of the above.
A fifth aspect of the present invention provides a battery comprising the negative electrode sheet described above.
According to the preparation method of the negative electrode slurry, a proper amount of graphite is added in the process of preparing the lithium titanate slurry, so that the compaction density of a negative electrode plate formed by coating the slurry is improved, and the energy density and the conductivity of a battery made of the lithium titanate material are improved.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 shows a battery capacity chart of charging and discharging of button cells prepared in example 4-example 8;
fig. 2 shows a battery capacity chart of charging and discharging of button cells prepared in example 9-example 13;
fig. 3 shows a battery capacity chart of charging and discharging of the button cell batteries manufactured in examples 7 and 13.
Detailed Description
The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in order to avoid obscuring the nature of the present invention, and well-known methods, procedures, and components have not been described in detail.
Furthermore, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.
Unless the context clearly requires otherwise, throughout the description and the claims, the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; that is, what is meant is "including, but not limited to".
In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In addition, in the description of the present invention, "a plurality" means two or more unless otherwise specified.
The invention provides a preparation method of cathode slurry, which comprises the following steps:
s10: mixing NMP (N-methyl pyrrolidone) and PVDF (binding agent) powder to obtain a first glue solution;
s20: adding super-p (conductive carbon black) into the first glue solution and stirring to obtain a second glue solution;
s30: and adding lithium titanate and graphite into the second glue solution and stirring to obtain the cathode slurry.
The theoretical gram capacity of the graphite in the negative electrode material can reach 372mAh/g, the graphite also has excellent battery cycle performance and rate capability within a certain temperature range, and meanwhile, the graphite material also has good conductivity. Therefore, in order to improve the battery performance of the LTO material, in the process of preparing the lithium titanate slurry, a proper amount of graphite is added, so that the compaction density of a negative plate formed by coating the slurry is improved, and the energy density and the conductivity of a battery made of the lithium titanate material are improved; compared with the method of coating lithium titanate by carbon, the method is simple and feasible.
Specifically, S10 mixes NMP and PVDF powder to obtain a first glue solution, specifically:
s11: NMP is stirred for one time, and PVDF powder is uniformly added at the same time to obtain a primary mixed glue solution;
s12: sequentially carrying out secondary stirring and tertiary stirring on the primary mixed glue solution;
wherein, the time of the second stirring is less than the time of the third stirring and is more than or equal to the time of the first stirring; the rotating speed of the primary stirring and the rotating speed of the tertiary stirring are both less than or equal to the rotating speed of the secondary stirring, namely, firstly, NMP is stirred in the primary stirring time, and PVDF powder is added at a constant speed; after the PVDF powder is added, stirring for a short time at a high rotating speed; then, the mixture was stirred at a relatively high rotation speed for a relatively long time, so that NMP was sufficiently and uniformly mixed with the PVDF powder.
Optionally, the time for one stirring is 0.2 hours to 0.5 hours, such as 0.2 hours, 0.4 hours, 0.5 hours; the time for the second stirring is 0.5 to 2 hours, such as 0.5, 1, 1.5, 2 hours; the time for three times of stirring is 6 hours to 12 hours, such as 6 hours, 8 hours, 10 hours and 12 hours; the rotation speed of the primary stirring is 200 rpm-400 rpm, such as 200rpm, 300rpm, 400rpm and the like; the rotation speed of the secondary stirring is 400 rpm-2000 rpm, such as 400rpm, 800rpm, 1000rpm, 1500rpm, 2000rpm and the like; the rotating speed of the three times of stirring is 200 rpm-400 rpm, such as 200rpm, 300rpm, 400rpm and the like, specifically, the speed of the one time of stirring can be 400rmp, and the time is 15 minutes; the speed of the secondary stirring is 1600rmp, and the time is 1 hour; the rotational speed of the three stirring operations was 300rmp for 12 hours. Of course, the time and the rotating speed of the first stirring, the second stirring and the third stirring can be determined according to actual needs.
It should be noted that the above-mentioned primary stirring, secondary stirring and tertiary stirring are all carried out at the same temperature, for example, all at 40 ℃, that is, the whole process of mixing NMP and PVDF to form the first glue solution is carried out at a constant temperature, and in practice, the whole process can be directly carried out in a constant temperature stirrer.
S20, adding super-p into the first glue solution and stirring to obtain a second glue solution, wherein the second glue solution comprises the following components:
and adding super-p into the first glue solution at a constant speed within a first preset time, and stirring in a mode of increasing the rotating speed to obtain a second glue solution. Specifically, the rotational speed may be increased from 300 to 600rmp to 3000 to 6000rmp, such as from 300 to 3000rpm, from 500 to 6000rpm, or from 600 to 5000 rpm.
S30, adding lithium titanate and graphite into the second glue solution, and stirring to obtain negative electrode slurry, wherein the negative electrode slurry specifically comprises the following components:
s31: alternately and uniformly adding lithium titanate and graphite into the second glue solution within the time range of 30-90 minutes, and stirring at a first rotating speed to obtain a mixed glue solution;
s32: stirring the mixed glue solution at a second rotating speed for 15-60 minutes, such as 15 minutes, 30 minutes, 45 minutes, 60 minutes and the like, so as to obtain negative electrode slurry;
wherein the first rotating speed is less than or equal to the second rotating speed, that is, the second glue solution is stirred at a lower rotating speed, lithium titanate and graphite are alternately added, and the lithium titanate and the graphite are added within 30-90 minutes; and then stirring the mixed glue solution at a high rotating speed for 15-60 minutes to uniformly mix the second glue solution, the lithium titanate and the graphite.
The first rotation speed can be 300rpm to 5000rpm, such as 300rpm, 1000rpm, 2000rpm, 4000rpm, 5000rpm and the like; the second rotating speed is 5000rpm to 8000rpm, such as 5000rpm, 7000rpm, 8000rpm and the like.
In preparing the formed anode slurry, active material: super-p: the mass ratio of PVDF is (90-96): (2-5): (2-5), such as 90: 5: 5. 94: 3: 3. 95: 3: 2. 95:2.5:2.5, 96:2:2 and the like, wherein the active substance comprises the lithium titanate and graphite, and the mass ratio of the lithium titanate to the graphite is (4-6): (4-6), such as 1: 1. 4:6, etc.
The viscosity of the prepared negative electrode slurry is 3500mpa · s to 5500mpa · s, such as 3500mpa · s, 4000mpa · s, 4500mpa · s, 5000mpa · s, 5500mpa · s and the like.
The fineness of the negative electrode slurry is 10-30 μm, such as 10, 12, 15, 20, 25, 28, 30 μm.
The solid content of the negative electrode slurry is 30-50%, such as 30%, 35%, 40%, 45%, 50% and the like.
The invention also provides a manufacturing method of the negative plate, which comprises the following steps:
preparing the negative electrode slurry by adopting the preparation method of any one of the embodiments;
then, vacuumizing the negative electrode slurry to remove bubbles in the negative electrode slurry;
then, coating the negative electrode slurry on a negative electrode current collector and drying, namely, coating and drying integration, wherein copper foil with the thickness of 8 microns can be selected as the negative electrode current collector to obtain a coated pole piece;
and finally, compacting the coated pole piece, namely rolling the coated pole piece by using a roll pair machine after coating is finished, wherein the rolling standard is that the compacted density reaches the set requirement after rolling is finished, so that the negative pole piece is obtained. By adopting the method to manufacture the negative plate, the graphite is doped into the negative electrode slurry, so that the compaction density of the negative plate can be improved, and the electrical property of the battery manufactured by the negative plate is improved.
In the process of coating the negative electrode slurry on the negative electrode current collector and drying, the coating speed is 5-12 inches/min, such as 5-6 inches/min, 8-inches/min, 10-inches/min, 12-inches/min, and the like, and specifically, the coating speed can be determined according to the performance of the material, the viscosity of the slurry and the solid content.
During coating and drying of the negative electrode slurry on the negative electrode current collector, the drying temperature can be increased in a two-stage temperature increasing mode, for example, the first-stage temperature is 108 ℃, and the second-stage temperature is 148 ℃, and the drying temperature can be specifically determined according to the properties of the material, the viscosity of the slurry and the solid content.
The areal density of the coated pole piece formed after coating was 55g/cm2～90g/cm2E.g. 55g/cm2、65g/cm2、75g/cm2、80g/cm2、85g/cm2、90g/cm2And the like.
The compaction density of the negative plate obtained by compaction can be 1.6g/cm3～2.3g/cm3E.g. 1.6g/cm3、1.8g/cm3、2.0g/cm3、2.2g/cm3、2.3g/cm3And the like.
In addition, the invention also provides negative electrode slurry prepared by the preparation method in any embodiment. The invention also provides a negative plate manufactured by the manufacturing method. Furthermore, the invention also provides a battery which can be a button battery and comprises the negative plate.
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
A method for manufacturing a negative electrode sheet, comprising:
s110: 596.6g of NMP is added into a constant temperature stirrer to be stirred for 15 minutes at the constant temperature of 40 ℃, 22.2g of PVDF powder is uniformly added within 15 minutes, meanwhile, the rotating speed of the stirrer is increased from 400rmp to 1600rmp, the 1600rmp rotating speed is kept to be stirred for 1 hour at high speed after the PVDF is added, finally, the stirring is carried out for 12 hours at 300rmp, and a first glue solution is obtained, wherein the whole pulping process is carried out at the temperature of 40 ℃.
S120: 22.2g of super-p is uniformly added into the prepared glue solution, and the stirring speed is increased from 400rmp to 3000rmp to obtain a second glue solution.
S130: 200g of LTO and 200g of graphite (BF-18) were alternately and uniformly added to the second glue solution over a period of 30 minutes while stirring at 1000 rmp; then, the mixture was stirred at a high speed of 6500rmp for 15 minutes to obtain a negative electrode slurry. And (3) measuring various data of the negative electrode slurry, wherein the active material: super-p: the mass ratio of PVDF is 90: 5: 5; the viscosity of the negative electrode slurry is 4000mpa · s; the fineness of the negative electrode slurry is 20 mu m; the solid content of the anode slurry was 40%.
S140: and after the negative electrode slurry is stirred, vacuumizing the prepared negative electrode slurry to remove bubbles in the negative electrode slurry.
S150: coating, namely using a copper foil with the thickness of 8 mu m as a negative current collector, integrating coating and drying, wherein the coating speed is 7 inches/min, drying is carried out in a two-stage heating oven, the first-order temperature is 108 ℃, the second-order temperature is 148 ℃, a coated pole piece is obtained, and the surface density of the coated pole piece is detected to be 82.3g/cm2。
S160: and (3) rolling the coated pole piece by using a roll-to-roll machine after coating is finished, wherein the rolling standard is that the compacted density meets the set requirement after rolling is finished, and thus the negative pole piece is obtained. For detecting negative pole pieceA compacted density of 2.0g/cm3。
Example 2
A method for manufacturing a negative electrode sheet, comprising:
s210: 596.6g of NMP is added into a constant temperature stirrer to be stirred at the constant temperature of 40 ℃ for 12 minutes, 22.2g of PVDF powder is uniformly added within 12 minutes, the rotating speed of the stirrer is increased from 200rmp to 400rmp, the rotating speed of 400mp is kept after the PVDF is added to be stirred at a high speed for 30 minutes, finally, the stirring is carried out at 400rmp for 14 hours to obtain a first glue solution, and the whole pulping process is carried out at the temperature of 40 ℃.
S220: 22.2g of super-p is uniformly added into the prepared glue solution, and the stirring speed is increased from 300rmp to 5000rmp to obtain a second glue solution.
S230: 200g of LTO and 200g of graphite (BF-18) were alternately and uniformly added to the second glue solution over a period of 60 minutes while stirring at 300 rmp; then, the mixture was stirred at a high speed of 5000rmp for 60 minutes to obtain a negative electrode slurry. And (3) measuring various data of the negative electrode slurry, wherein the active material: super-p: the mass ratio of PVDF is 94: 2: 3; the viscosity of the negative electrode slurry was 3500mpa · s; the fineness of the negative electrode slurry is 10 mu m; the solid content of the negative electrode slurry was 30%.
S240: and after the stirring of the cathode slurry is finished, vacuumizing the prepared cathode slurry to remove bubbles in the cathode slurry.
S250: coating, namely using copper foil with the thickness of 8 mu m as a negative current collector, integrating coating and drying at the coating speed of 5 inches/min, drying in a two-stage heating oven with the first-stage temperature of 109 ℃ and the second-stage temperature of 149 ℃ to obtain a coated pole piece, obtaining a coated pole piece, and detecting that the areal density of the coated pole piece is 55g/cm2。
S260: and (3) rolling the coated pole piece by using a roll-to-roll machine after coating is finished, wherein the rolling standard is that the compacted density meets the set requirement after rolling is finished, and thus the negative pole piece is obtained. Detecting the compaction density of the negative plate to be 1.6g/cm3。
Example 3
A method for manufacturing a negative electrode sheet, comprising:
s310: 596.6g of NMP is added into a constant temperature stirrer to be stirred for 30 minutes at the constant temperature of 40 ℃, 22.2g of PVDF powder is uniformly added within 30 minutes, meanwhile, the rotating speed of the stirrer is increased from 350rmp to 2000rmp, after the PVDF is added, the rotating speed of 2000rmp is kept to be stirred at a high speed for 2 hours, finally, the stirring is carried out for 6 hours at 200rmp, a first glue solution is obtained, and the whole pulping process is carried out at the temperature of 40 ℃.
S320: 22.2g of super-p was added uniformly to the prepared dope solution, with the stirring speed from? 600rmp was increased to 6000rmp to obtain a second dope.
S330: 200g of LTO and 200g of graphite (BF-18) were alternately and uniformly added to the second glue solution within 90 minutes while stirring at 5000 rmp; then, the mixture was stirred at a high speed of 8000rmp for 20 minutes to obtain a negative electrode slurry. And (3) measuring various data of the negative electrode slurry, wherein the activity of the negative electrode slurry is as follows: super-p: the mass ratio of PVDF is 96: 3: 2; the viscosity of the negative electrode slurry is 5500mpa · s; the fineness of the negative electrode slurry is 30 mu m; the solid content of the anode slurry was 50%.
S340: and after the stirring of the cathode slurry is finished, vacuumizing the prepared cathode slurry to remove bubbles in the cathode slurry.
S350: coating, adopting copper foil with the thickness of 8 mu m as a negative current collector, integrating coating and drying, wherein the coating speed is 12 inches/min, drying is carried out in a two-section temperature-rising oven, the first-order temperature is 120 ℃, the second-order temperature is 150 ℃, obtaining a coated pole piece, and detecting the surface density of the coated pole piece to be 90g/cm2。
S360: and (3) rolling the coated pole piece by using a roll-to-roll machine after coating is finished, wherein the rolling standard is that the compaction density meets the set requirement after rolling is finished, so as to obtain the negative pole piece. The compacted density of the negative pole piece is detected to be 2.3g/cm3。
Example 4
Unlike example 1, the areal density of the coated pole piece formed after S150 coating and drying was 81.87g/cm2(ii) a The compacted density of the cathode sheet after S160 rolling is 1.6g/cm3。
Example 5
Unlike example 4, the compacted density of the negative electrode sheet after S160 rolling was 1.7g/cm3。
Example 6
Unlike example 4, the compacted density of the negative electrode sheet after S160 rolling was 1.8g/cm3。
Example 7
Unlike example 4, the compacted density of the negative electrode sheet after S160 rolling was 1.9g/cm3。
Example 8
Unlike example 4, the compacted density of the negative electrode sheet after S160 rolling was 2.0g/cm3。
Example 9
Different from the embodiment 1, the surface density of the coating pole piece formed after S150 coating and drying is 60.51g/cm2(ii) a The compacted density of the cathode sheet after S160 rolling is 1.6g/cm3。
Example 10
Unlike example 9, the compacted density of the negative electrode sheet after S160 rolling was 1.7g/cm3。
Example 11
Unlike example 9, the compacted density of the negative electrode sheet after S160 roll pressing was 1.8g/cm3。
Example 12
Unlike example 9, the compacted density of the negative electrode sheet after S160 rolling was 1.9g/cm3。
Example 13
Unlike example 9, the compacted density of the negative electrode sheet after S160 roll pressing was 2.0g/cm3。
And (2) assembling the button cell by taking the negative plate prepared in each example as a negative electrode and the lithium plate as a positive electrode, wherein the conductive agent adopts conductive carbon super-p, the diaphragm is celgard 2400, and the electrolyte adopts 1mol/L LiPF6 conductive salt and DMC, DEC (wt%): 1: 1. The test is carried out, wherein the charge-discharge cut-off voltage of the example 1 is 0.05-2.5V, the theoretical gram capacity is 277mAh/g, and the multiplying factor type charge-discharge test is carried out by the charge-discharge current of 0.2C, 1C and 2C.
Referring to fig. 1-3, fig. 1 shows the charge and discharge capacity of the button cell made in examples 4-8, fig. 2 shows the charge and discharge capacity of the button cell made in examples 9-13, and fig. 3 shows the charge and discharge capacity of the button cell made in examples 7-13. As can be seen from FIG. 1, the areal density at the time of coating was 81.87g/cm2Under the condition, the compacted density of the pole piece is 1.9g/cm3The half-cell capacity and rate capability of the material are better; as can be seen from FIG. 2, the areal density at the time of coating was 60.54g/cm2Under the condition, the compacted density of the pole piece is 2.0g/cm3The half-cell capacity and rate capability of the material are better. FIG. 3 shows that the coating surface density is 60.54g/cm by comparing the different coating surface density data2The half cell has better test effect and higher capacity exertion of the material. From the half-cell test data, in the process of preparing the negative electrode slurry, the ratio of lithium titanate: the graphite is prepared by mixing the following components in percentage by weight of 1: 1 can improve the capacity of the material, has excellent rate performance, can achieve the first discharge of about 360mAh/g (the theoretical gram capacity of lithium titanate is 175mAh/g, the theoretical gram capacity of graphite is 375mAh/g), improves the compaction density of the material, and can achieve the maximum compaction density of 2.1g/cm3About (maximum compaction of graphite 1.6 g/cm)3Maximum compaction of LTO of 1.9g/cm3)。
Therefore, the negative plate manufactured by the preparation method of the negative electrode slurry and the manufacturing method of the negative plate provided by the invention can improve the energy density and the conductivity of the battery, and the method is simple and easy to implement and is suitable for industrial application.
Those skilled in the art will readily appreciate that the above-described preferred embodiments may be freely combined, superimposed, without conflict.
It will be understood that the embodiments described above are illustrative only and not restrictive, and that various obvious and equivalent modifications and substitutions for details described herein may be made by those skilled in the art without departing from the basic principles of the invention.
Claims (13)
1. A method for preparing anode slurry is characterized by comprising the following steps:
mixing NMP and PVDF powder to obtain a first glue solution;
adding super-p into the first glue solution and stirring to obtain a second glue solution;
adding lithium titanate and graphite into the second glue solution and stirring to obtain negative electrode slurry;
the method comprises the following steps of mixing NMP and PVDF powder to obtain a first glue solution, specifically:
the NMP is stirred for the first time, and meanwhile, the PVDF powder is uniformly added to obtain a primary mixed glue solution;
sequentially carrying out secondary stirring and tertiary stirring on the primary mixed glue solution;
wherein the time of the second stirring is less than the time of the third stirring and is more than or equal to the time of the first stirring; the rotating speed of the primary stirring and the rotating speed of the tertiary stirring are both less than or equal to the rotating speed of the secondary stirring;
adding super-p into the first glue solution and stirring to obtain a second glue solution, wherein the method specifically comprises the following steps:
adding the super-p into the first glue solution at a constant speed within a first preset time, and stirring in a mode of increasing the rotating speed to obtain a second glue solution;
adding lithium titanate and graphite into the second glue solution and stirring to obtain negative electrode slurry, wherein the negative electrode slurry specifically comprises the following components:
alternately and uniformly adding the lithium titanate and the graphite into the second glue solution within the time range of 30-90 minutes, and stirring at a first rotating speed to obtain a mixed glue solution;
stirring the mixed glue solution at a second rotating speed for 15-60 minutes to obtain the cathode slurry;
wherein the first rotational speed is less than or equal to the second rotational speed;
in the negative electrode slurry, an active material: the super-p: the PVDF is prepared from the following components in percentage by mass (90-96): (2-5): (2-5), wherein the active material comprises the lithium titanate and the graphite; the mass ratio of the lithium titanate to the graphite is (4-6): (4-6).
2. The production method according to claim 1, wherein the primary stirring, the secondary stirring, and the tertiary stirring are all performed at the same temperature.
3. The method for preparing the resin composition according to claim 1, wherein the stirring is performed while increasing the rotation speed, and the rotation speed is increased from 300rpm to 600rpm to 3000rpm to 6000 rpm.
4. The method of claim 1, wherein the first rotation speed is 300rmp to 5000 rmp; the second rotating speed is 5000-8000 rmp.
5. The production method according to claim 1, characterized in that the viscosity of the negative electrode slurry is 3500 mpa-s to 5500 mpa-s;
and/or the fineness of the negative electrode slurry is 10-30 mu m;
and/or the solid content of the negative electrode slurry is 30-50%.
6. A method for manufacturing a negative electrode sheet, comprising:
preparing a negative electrode slurry by the preparation method according to any one of claims 1 to 5;
vacuumizing the negative electrode slurry;
coating the negative electrode slurry on a negative electrode current collector and drying to obtain a coated pole piece;
and compacting the coating pole piece to obtain the negative pole piece.
7. The manufacturing method according to claim 6, wherein the coating speed of the negative electrode slurry on the negative electrode current collector and the drying is 5-12 inches/min.
8. The manufacturing method according to claim 6, wherein in the step of coating the negative electrode slurry on the negative electrode current collector and drying, the drying temperature is increased by a two-stage temperature increase manner.
9. The manufacturing method according to claim 6, wherein the areal density of the coated pole piece is 55g/cm 2-90 g/cm 2.
10. The manufacturing method according to claim 6, wherein the compacted density of the negative electrode sheet is 1.6g/cm3 to 2.3g/cm 3.
11. An anode slurry produced by the production method according to any one of claims 1 to 5.
12. A negative electrode sheet produced by the production method according to any one of claims 6 to 10.
13. A battery comprising the negative electrode sheet of claim 12.
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| KR20150083635A (en) * | 2014-01-10 | 2015-07-20 | 주식회사 엘지화학 | A method of preparing an anode slurry composition comprising a dispersed mixture of conductive additive covered lto and graphite |
| CN105633409A (en) * | 2016-03-22 | 2016-06-01 | 成都雅骏新能源汽车科技股份有限公司 | Paste making method for negative electrode mixed powder of lithium titanate and graphite material |
| CN106299332A (en) * | 2016-11-02 | 2017-01-04 | 天津市捷威动力工业有限公司 | A kind of safe power lithium-ion battery of height using lithium titanate blending graphite cathode sheet |
| CN107834048A (en) * | 2017-11-24 | 2018-03-23 | 深圳市比克动力电池有限公司 | Negative electrode of lithium titanate battery slurry and preparation method thereof |
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| KR20150083635A (en) * | 2014-01-10 | 2015-07-20 | 주식회사 엘지화학 | A method of preparing an anode slurry composition comprising a dispersed mixture of conductive additive covered lto and graphite |
| CN105633409A (en) * | 2016-03-22 | 2016-06-01 | 成都雅骏新能源汽车科技股份有限公司 | Paste making method for negative electrode mixed powder of lithium titanate and graphite material |
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