A proportion detection method for double-layer coated pole piece

Abstract

The application discloses a proportion detection method for double-layer coated pole pieces, which comprises the following steps: preparing CMC glue and stirring, and adding SWCNT conductive glue at the same time; mixing and stirring main materials, SP, CMC glue and SWCNT slurry; finally, adding SBR emulsion and stirring at low speed, and adjusting according to the viscosity requirement range to obtain final slurry; according to the obtained final slurry, different proportions of graphite are coated on the pole pieces through a coating die, and the pole pieces are verified at different compaction densities; the pole pieces at different compaction densities are subjected to OI value determination, and the determination results are compared in cycle performance to obtain comparison results of different cycle data. The application determines the difference between the proportion design value and the actual value of the double-layer coating through the size of the OI value; in addition, for the bottom layer graphite negative electrode, natural graphite can be used, so that the cost of artificial graphite can be greatly reduced, and the cost of the whole battery can be reduced.

Description

Technical Field

[0001] This invention relates to the field of negative electrode double-layer coating application technology, and in particular to a method for detecting the proportion of double-layer coated electrodes. Background Technology

[0002] In the application of double-layer coating technology for anode materials, graphite with excellent fast-charging performance is typically selected for the outer layer, while high-capacity and high-compactness graphite is selected for the bottom layer to balance the requirements of fast-charging performance and high energy density. The ratio of the two types of graphite in double-layer coating technology varies. To ensure consistent performance after coating, this patent introduces a new technology that can accurately determine the ratio of the upper and lower layers in double-layer coating and ensure the consistency of coating parameters with the set values.

[0003] In contrast, in single-layer coating processes, the negative electrode material is singular, allowing for online monitoring to ensure consistent coating density and determine the appropriate proportions. However, in double-layer coating processes, the use of two different types of graphite makes it difficult to confirm the ratio of these two graphites online using existing techniques, thus compromising coating consistency and stability. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the existing technology. To achieve the above objective, a proportional detection method for double-coated electrode sheets is adopted to solve the problems mentioned in the background technology.

[0005] A method for detecting the proportion of double-coated electrode sheets includes the following steps:

[0006] Step S1: Prepare slurry: Prepare CMC adhesive and stir it, while adding SWCNT conductive adhesive; then add the main material and SP, and stir at high speed. Finally, add SBR emulsion and stir at low speed, and adjust according to the viscosity requirements to obtain the final slurry.

[0007] Step S2: Based on the obtained final slurry, apply different proportions of graphite to the electrode using a coating die, and verify the electrode with different compaction densities.

[0008] Step S3: Next, measure the OI value of the electrodes with different compaction densities, and compare the cycle performance of the measurement results to obtain the comparison results of different cycle data.

[0009] As a further aspect of the present invention, the specific steps in step S1 include:

[0010] Step S11: Apply the obtained CMC adhesive solution to the glue, and stir according to the preset solid content m1, stirring speed v1, and time t1 to prepare CMC adhesive solution and obtain a portion of CMC adhesive solution.

[0011] Step S12: Obtain SWCNT slurry and stir it according to the preset stirring speed v2 and time t2 to prepare conductive adhesive solution;

[0012] Step S13: Add the first part of the main ingredients, stir according to the preset stirring speed v3 and time t3, and then add SP and the second part of the main ingredients;

[0013] Step S14: Add a portion of the adhesive solution from step S11 to the obtained SWCNT slurry and stir at high speed according to the preset stirring speed v4 and time t4.

[0014] Step S15: Add SBR emulsion and stir at low speed according to the preset stirring speed v5 and time t5;

[0015] Step S16: Finally, viscosity control is performed according to the viscosity range f required by the process standard slurry to obtain the final slurry. By refining each sub-step in step S1 and setting specific parameters, such as stirring speed, time, and solid content, the slurry preparation process can be controlled more precisely, thereby improving the quality and stability of the slurry.

[0016] As a further aspect of the present invention, the specific steps in step S11 include:

[0017] Obtain the slurry ratio and apply adhesive to the obtained CMC;

[0018] During the glue application process, based on the predetermined ratio, the CMC solid content m1 was determined to be 1.65%. The stirring speed was v1 of 30 / 30Hz, and the stirring time t1 was 3h. The CMC glue solution was obtained, and 40% of the CMC glue solution was taken out.

[0019] As a further aspect of the present invention: the stirring speed v2 in step S12 is 30 / 30Hz, and the time t2 is 2h.

[0020] As a further aspect of the present invention: the stirring speed v3 in step S13 is 10 / 5Hz, and the time t3 is 30min. These specific parameters and steps ensure the uniform mixing of CMC adhesive, SWCNT slurry, and main materials, providing a guarantee for the preparation of high-quality slurry.

[0021] As a further aspect of the present invention, the specific steps in step S14 include:

[0022] Add 40% of the CMC adhesive solution taken in step S11 to the slurry and stir at high speed (v4) of 35 / 30 Hz for 2 hours (t4). Low-speed stirring avoids breaking down particles in the slurry while ensuring uniform distribution of the SBR emulsion, further improving the slurry's performance.

[0023] As a further aspect of the present invention, the specific steps in step S15 include:

[0024] The slurry after high-speed mixing in step S14 is added to the SBR emulsion, and high-speed mixing is performed at a mixing speed v5 of 12 / 10Hz and a time t4 of 1 hour. High-speed mixing further ensures the uniform mixing of CMC adhesive and SWCNT slurry, improving the stability and performance of the slurry.

[0025] As a further aspect of the present invention, the specific steps in step S16 include:

[0026] Viscosity is controlled within the range of 5000-7000 mPa·s, which is the viscosity requirement of the process standard slurry. If f exceeds the process standard, adjustments are made to obtain the final slurry. Viscosity control ensures that the slurry viscosity is within the process standard range, thus meeting the requirements of subsequent coating and battery production.

[0027] As a further aspect of the present invention, the specific steps in step S2 include:

[0028] Step S21: First, a single-layer coating technique is used, with graphite A as the upper layer and graphite B as the lower layer, and the areal density is controlled between 90-120 g / m³. 2 Within the range;

[0029] Step S22: Next, a double-layer coating die was used for coating, wherein the upper layer is graphite A and the lower layer is graphite B, and the double-layer coating was carried out in different proportions, with the areal density ranging from 180-240 g / m³. 2 between;

[0030] The upper slurry composition is as follows: graphite A:CMC:SP:SWCNT:SBR = 96.73%:1.25%:1.0%:0.02%:1.0%;

[0031] The lower layer slurry ratio is graphite B:CMC:SP:SWCNT:SBR = 96.18%:1.25%:0.7%:0.02%:1.85%;

[0032] Step S23: Verify the prepared electrode sheets with different compaction densities. By using single-layer and double-layer coating techniques, the optimal coating method and graphite ratio can be explored, thereby improving the energy density and performance of the battery.

[0033] As a further aspect of the present invention, the specific steps in step S3 include:

[0034] Step S31: The OI values ​​of the electrodes with different compaction densities from step S2 are measured using an XRD device to obtain the OI value measurement results.

[0035] Step S32: Obtain the OI value measurement results. Based on the ratio of the double-layer coating, obtain the comparison results of different cycling data. By measuring the OI value and comparing the cycling performance, we can gain a deeper understanding of the impact of different compaction densities and coating ratios on battery performance, providing strong support for optimizing battery design.

[0036] Compared with the prior art, the present invention has the following technical advantages:

[0037] By adopting the above technical solution, a slurry containing CMC adhesive, SWCNT conductive adhesive, main material, SP and SBR emulsion is precisely configured and adjusted according to viscosity requirements. Then, a coating die is used to coat the electrode with different proportions of graphite and verify different compaction densities. Finally, the OI value of the electrode with different compaction densities is measured and the cycle performance is compared. This optimizes the slurry configuration and coating process, and significantly improves the energy density, cycle stability and overall performance of the battery. Attached Figure Description

[0038] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings:

[0039] Figure 1 This is a schematic diagram illustrating the steps of the proportional detection method according to an embodiment of this application;

[0040] Figure 2 This is a schematic diagram of single-layer coating and double-layer coating according to embodiments disclosed in this application;

[0041] Figure 3 This is a schematic diagram comparing the cyclic performance of embodiments disclosed in this application. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] Please refer to Figure 1 In this embodiment of the invention, a method for detecting the proportion of a double-coated electrode includes the following steps:

[0044] Step S1: Prepare the slurry: Prepare and stir the CMC adhesive solution, while simultaneously adding the SWCNT conductive adhesive solution; then add the main material and SP, and stir at high speed. Finally, add the SBR emulsion and stir at low speed, adjusting the viscosity according to the required range to obtain the final slurry. The specific steps include:

[0045] Step S11: Apply the obtained CMC adhesive solution to a foam, and stir according to the preset solid content m1, stirring speed v1, and time t1 to prepare the CMC adhesive solution and obtain a portion of the CMC adhesive solution; the specific steps include:

[0046] Obtain the slurry ratio and apply adhesive to the obtained CMC;

[0047] During the glue application process, based on the predetermined ratio, the CMC solid content m1 was determined to be 1.65%. The stirring speed was v1 of 30 / 30Hz, and the stirring time t1 was 3h. The CMC glue solution was obtained, and 40% of the CMC glue solution was taken out.

[0048] Step S12: Obtain SWCNT slurry and stir it according to the preset stirring speed v2 and time t2 to prepare conductive adhesive solution;

[0049] The stirring speed v2 is 30 / 30Hz, and the time t2 is 2h.

[0050] Step S13: Add the first part of the main ingredients, stir according to the preset stirring speed v3 and time t3, and then add SP and the second part of the main ingredients;

[0051] The stirring speed v3 is 10 / 5Hz, and the time t3 is 30min.

[0052] Step S14: Add a portion of the adhesive solution from step S11 to the obtained SWCNT slurry, and perform high-speed stirring according to the preset stirring speed v4 and time t4. The specific steps include:

[0053] Add 40% of the CMC adhesive solution taken in step S11 to the slurry and stir at high speed with a stirring speed v4 of 35 / 30Hz and a time t4 of 2h.

[0054] Step S15: Add the SBR emulsion and stir at low speed according to the preset stirring speed v5 and time t5. The specific steps include:

[0055] The slurry after high-speed mixing in step S14 is added to the SBR emulsion and mixed at a mixing speed of 12 / 10Hz (v5) for 1 hour (t4).

[0056] Step S16: Finally, control the viscosity according to the viscosity range f required by the process standard slurry to obtain the final slurry. The specific steps include:

[0057] Viscosity is controlled within the range of 5000-7000 mPa·s, which is the viscosity requirement of the process standard slurry. If f exceeds the process standard, adjustments are made to obtain the final slurry. Viscosity control ensures that the slurry viscosity is within the process standard range, thus meeting the requirements of subsequent coating and battery production.

[0058] Step S2: Based on the obtained final slurry, different proportions of graphite are coated onto the electrode using a coating die, and the electrode is then subjected to verification at different compaction densities. The specific steps include:

[0059] like Figure 2 As shown, the diagram illustrates single-layer coating and double-layer coating.

[0060] Step S21: First, a single-layer coating technique is used, with graphite A as the upper layer and graphite B as the lower layer, and the areal density is controlled between 90-120 g / m³. 2 Within the range;

[0061] By rolling single-layer (upper and lower) graphite electrodes with different compaction densities (from 1.4-1.8 g / cc), the OI value of the negative electrode with different compaction densities is calculated. For double-layer coated electrodes, under certain pressure conditions, the OI value of the double coating is calculated. Combining the single-layer OI value with the double-layer OI value at different compaction densities, the different compaction densities of the upper and lower layers in the double coating can be deduced, thus ensuring that the deviation in compaction density between different layers is less than 0.5%.

[0062] Step S22: Next, a double-layer coating die was used for coating, wherein the upper layer is graphite A and the lower layer is graphite B, and the double-layer coating was carried out in different proportions, with the areal density ranging from 180-240 g / m³. 2 between;

[0063] The upper slurry composition is as follows: graphite A:CMC:SP:SWCNT:SBR = 96.73%:1.25%:1.0%:0.02%:1.0%;

[0064] The lower layer slurry ratio is graphite B:CMC:SP:SWCNT:SBR = 96.18%:1.25%:0.7%:0.02%:1.85%;

[0065] Step S23: Verify the prepared electrode sheets with different compaction densities.

[0066] In this embodiment, the formula and its proportions are shown in the table below:

[0067]

[0068]

[0069]

[0070] Based on the above, the materials can be selected as follows:

[0071] Negative electrode 1 / Negative electrode 2: Graphite, hard carbon, silicon carbide, etc.;

[0072] Adhesive 1 / Adhesive 2: CMC, SBR, PAA, styrene-acrylic, etc.;

[0073] Conductive agent 1 / Conductive agent 2: Carbon black, carbon nanotubes, acetylene black, Ketjen black, VGCF, etc.;

[0074] Copper foil selection: 3-6 micrometer copper foil, copper foil width: 200-1400 mm;

[0075] Step S3: Next, the OI values ​​of electrodes with different compaction densities are measured, and the cycling performance of the measurement results is compared to obtain comparative results of different cycling data. The specific steps include:

[0076] Step S31: The OI values ​​of the electrodes with different compaction densities from step S2 are measured using an XRD device to obtain the OI value measurement results.

[0077] In this embodiment, the method for testing the OI value is as follows:

[0078] ① First, set the parameters of the XRD equipment, including a scanning range of 10-90°, a step size of 0.01, and a scanning speed of 5° / min, to obtain the raw XRD data;

[0079] ② Use analysis software to obtain XRD peak intensity data, OI value = I004 / I110(I002 / I110).

[0080] In this embodiment, the DOE designs with different proportions for double-layer coating are shown in the table below:

[0081]

[0082] Step S32: Obtain the OI value measurement results, and based on the ratio of double coating, obtain the comparison results of different cycle data.

[0083] In this embodiment, the measurement results are shown in the table below:

[0084]

[0085] In this embodiment, the beneficial effects are:

[0086] The difference between the designed and actual proportions of a two-layer coating can be determined by the magnitude of the OI value.

[0087] In addition, natural graphite can be used for the bottom graphite anode, which can significantly reduce the cost of artificial graphite, thereby reducing the overall cost of the battery cell and improving bargaining power.

[0088] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention, and no reference numerals in the claims should be construed as limiting the scope of the claims.

[0089] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for detecting the proportion of double-coated electrode sheets, characterized in that, Includes the following steps: Step S1: Prepare slurry: Prepare CMC adhesive and stir it, while adding SWCNT conductive adhesive; then add the main material and SP, and stir at high speed. Finally, add SBR emulsion and stir at low speed, and adjust according to the viscosity requirements to obtain the final slurry. Step S2: Based on the obtained final slurry, apply different proportions of graphite to the electrode using a coating die, and verify the electrode with different compaction densities. Step S3: Next, measure the OI value of the electrodes with different compaction densities, and compare the cycle performance of the measurement results to obtain the comparison results of different cycle data.

2. The method for detecting the proportion of double-layer coated electrodes according to claim 1, characterized in that, The specific steps in step S1 include: Step S11: Apply the obtained CMC adhesive solution to the glue, and stir according to the preset solid content m1, stirring speed v1, and time t1 to prepare CMC adhesive solution and obtain a portion of CMC adhesive solution. Step S12: Obtain SWCNT slurry and stir it according to the preset stirring speed v2 and time t2 to prepare conductive adhesive solution; Step S13: Add the first part of the main ingredients, stir according to the preset stirring speed v3 and time t3, and then add SP and the second part of the main ingredients; Step S14: Add a portion of the adhesive solution from step S11 to the obtained SWCNT slurry and stir at high speed according to the preset stirring speed v4 and time t4. Step S15: Add SBR emulsion and stir at low speed according to the preset stirring speed v5 and time t5; Step S16: Finally, control the viscosity according to the viscosity range f of the slurry in the process standard to obtain the final slurry.

3. The method for detecting the proportion of double-layer coated electrodes according to claim 2, characterized in that, The specific steps in step S11 include: Obtain the slurry ratio and apply adhesive to the obtained CMC; During the glue application process, based on the predetermined ratio, the CMC solid content m1 was determined to be 1.65%. The stirring speed was v1 of 30 / 30Hz, and the stirring time t1 was 3h. The CMC glue solution was obtained, and 40% of the CMC glue solution was taken out.

4. The method for detecting the proportion of double-layer coated electrodes according to claim 3, characterized in that, In step S12, the stirring speed v2 is 30 / 30Hz and the time t2 is 2h.

5. The method for detecting the proportion of a double-coated electrode sheet according to claim 4, characterized in that, In step S13, the stirring speed v3 is 10 / 5Hz and the time t3 is 30min.

6. The method for detecting the proportion of a double-coated electrode sheet according to claim 5, characterized in that, The specific steps in step S14 include: Add 40% of the CMC adhesive solution taken in step S11 to the slurry and stir at high speed with a stirring speed v4 of 35 / 30Hz and a time t4 of 2h.

7. The method for detecting the proportion of a double-coated electrode sheet according to claim 6, characterized in that, The specific steps in step S15 include: The slurry after high-speed mixing in step S14 is added to the SBR emulsion and mixed at a mixing speed of 12 / 10Hz (v5) for 1 hour (t4).

8. The method for detecting the proportion of a double-coated electrode sheet according to claim 7, characterized in that, The specific steps in step S16 include: Viscosity is controlled within the range of 5000-7000 mPa·s, which is the viscosity requirement of the process standard slurry. If f exceeds the process standard, it is adjusted to obtain the final slurry.

9. The method for detecting the proportion of double-layer coated electrodes according to claim 1, characterized in that, The specific steps in step S2 include: Step S21: First, a single-layer coating technique is used, with graphite A as the upper layer and graphite B as the lower layer, and the areal density is controlled between 90-120 g / m³. 2 Within the range; Step S22: Next, a double-layer coating die was used for coating, wherein the upper layer is graphite A and the lower layer is graphite B, and the double-layer coating was carried out in different proportions, with the areal density ranging from 180-240 g / m³. 2 between; The upper slurry composition is as follows: graphite A:CMC:SP:SWCNT:SBR = 96.73%:1.25%:1.0%:0.02%:1.0%; The lower layer slurry ratio is graphite B:CMC:SP:SWCNT:SBR = 96.18%:1.25%:0.7%:0.02%:1.85%; Step S23: Verify the prepared electrode sheets with different compaction densities.

10. The method for detecting the proportion of a double-layer coated electrode according to claim 1, characterized in that, The specific steps in step S3 include: Step S31: The OI values ​​of the electrodes with different compaction densities from step S2 are measured using an XRD device to obtain the OI value measurement results. Step S32: Obtain the OI value measurement results, and based on the ratio of double coating, obtain the comparison results of different cycle data.

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