A coating surface density online detection method and device and a battery coating equipment

Abstract

This application provides an online detection method, apparatus, and battery coating equipment for coating surface density. The online detection method for coating surface density is applied to a battery coating machine and includes the following steps: S1, obtaining the electrode coating area of ​​the introduced electrode roll from an initial time t0 to the current time t1; S2, obtaining the initial electrode roll weight M0 at initial time t0 and the current electrode roll weight M1 at current time t1; S3, calculating the coating surface density based on the initial electrode roll weight M0, the current electrode roll weight M1, and the electrode coating area. According to the online detection method for coating surface density of this invention, online detection of coating surface density can be achieved without stopping the machine for sampling. Furthermore, during the detection process, the coating surface density can be calculated by obtaining the weight at the initial and current times and the electrode coating area of ​​the introduced electrode roll, thus improving the safety and efficiency of online detection of coating surface density.

Description

Technical Field

[0001] This invention relates to the field of coating, and more specifically to an online detection method, apparatus, and battery coating equipment for coating surface density. Background Technology

[0002] Lithium-ion batteries have advantages such as high energy density, long lifespan, and environmental friendliness, leading to their increasing use. In the lithium-ion battery manufacturing process, the quality of the coating directly determines the battery's quality, and the coating quality is directly affected by the coating surface density. Therefore, it is necessary to test the coating surface density during the lithium-ion battery manufacturing process to control the coating quality.

[0003] In existing technologies, there are generally two methods for measuring coating surface density. One method involves taking material from the coating machine while it is stopped, weighing the material, and then calculating the surface density. The other method involves installing an X / β-ray surface density measuring instrument at the tail of the coating machine. X / β rays attenuate as they penetrate the coating electrode, and since this attenuation follows an exponential law and is related to the coating surface density, the surface density can be measured based on the attenuation of the probe rays. However, both methods have drawbacks. The former requires material to be taken from the stopped machine, which affects production efficiency and can lead to the scrapping of individual cores when rewinding, impacting the product's yield. The latter method requires a windless environment or a stable foil material for accurate measurement, and the equipment releases X / β rays during the measurement process, which is harmful to humans and the environment. Summary of the Invention

[0004] In view of this, the present invention provides an online detection method for coating surface density that enables online detection.

[0005] The present invention also provides an online detection device for coating surface density.

[0006] The present invention also provides a battery coating apparatus.

[0007] The online detection method for coating surface density according to a first aspect of the present invention, applied to a battery coating machine, includes the following steps:

[0008] S1, obtain the electrode coating area introduced from the initial time t0 to the current time t1;

[0009] S2, obtain the initial polar roll weight M0 at the initial time t0 and the current polar roll weight M1 at the current time t1 respectively;

[0010] S3. Calculate the coating density based on the initial electrode roll weight M0, the current electrode roll weight M1, and the electrode coating area.

[0011] Further, step S1 includes:

[0012] Determine the winding speed V;

[0013] Based on the initial time t0 to the current time t1, determine the time interval Δt;

[0014] Obtain the coating width L;

[0015] Based on the winding speed V, the time interval Δt, and the coating width L, the electrode coating area S corresponding to the time interval Δt is determined according to the following formula 1).

[0016] S=V*⊿t*L 1).

[0017] Further, step S3 includes:

[0018] S31, based on the initial polar roll weight M0 and the current polar roll weight M1, determine the polar roll weight difference ΔM corresponding to the time interval Δt, where ΔM = M1 - M0;

[0019] S32, obtain the winding tension F, and determine the first weight change correction amount Δm1 based on the winding tension F;

[0020] S33, based on the polar roll weight change ΔM and the first weight change correction amount Δm1, the corrected weight difference ΔM' is obtained;

[0021] S34, Calculate the coating surface density ρ based on the corrected weight difference ΔM' and the electrode coating area S. m , where ρ m =⊿M' / S.

[0022] Further, step S32 includes:

[0023] S321, Obtain the winding tension F;

[0024] S322, obtain the polar radius R0 at the initial time t0 and the polar radius R1 at the current time t1;

[0025] S323, based on the polar roll radii R1 and R0, the initial angle θ0 between the introduced part of the polar roll and the horizontal plane at the initial time t0 and the current angle θ1 at the current time are determined by the angle determination model.

[0026] S324, based on the winding tension F, the output angle θ0, and the current angle θ1, determine the first weight change correction amount Δm1, wherein the first weight change correction amount Δm1 = F(sinθ1-sinθ0) / g, where g is the gravitational acceleration.

[0027] Furthermore, the angle determination model is determined as follows:

[0028] The calibration radius of the polar roll at multiple different times, and the corresponding calibration angle between the introduced part of the polar roll and the horizontal plane, were obtained respectively.

[0029] The angle determination model is obtained based on the multiple calibration polar radius and calibration angle.

[0030] Furthermore, step S3 may also include:

[0031] S35, determine the second weight change correction amount Δm2=ρ*V*Δt*l of the substrate of the electrode sheet introduced into the electrode roll from the initial time t0 to the current time t1, where l is the width of the substrate and ρ is the areal density of the substrate;

[0032] In step S33, the corrected weight difference ΔM' = ΔM + Δm1 - Δm2 is obtained based on the polar roll weight change ΔM, the first weight change correction amount Δm1, and the second weight change correction amount Δm2.

[0033] Furthermore, when the Δt is less than a predetermined value, the coating surface density ρ is determined by the following formula 2). m :

[0034] ρ m =[(⊿M-⊿m2] / (V*⊿t*L) 2).

[0035] According to a second aspect of the present invention, an online coating density detection device is applied to a battery coating machine, comprising:

[0036] A weighing unit is provided, which is disposed below the winding device of the battery coating machine to weigh the electrode roll.

[0037] The calculation unit calculates the coating surface density based on the coating speed, coating width, and the difference in the weight of the electrode roll at different times.

[0038] Furthermore, the online coating surface density detection device also includes:

[0039] A thickness detection unit, which is used to detect the radius of the electrode roll;

[0040] The calculation unit determines the angle between the introduced portion of the electrode roll and the horizontal plane based on the radius using an angle determination model. Based on the angle and the winding tension, it determines a first weight correction amount. After correcting the difference in the weight of the electrode roll based on the first weight correction amount, it calculates the coating surface density.

[0041] Furthermore, the online coating density detection device of this embodiment may further include:

[0042] An early warning unit receives the coating surface density calculated by the calculation unit and issues an early warning when the coating surface density exceeds a predetermined threshold range.

[0043] A battery coating apparatus according to a third aspect of the present invention includes:

[0044] Battery coating machine; and

[0045] The online coating surface density detection device according to any of the above claims.

[0046] The above-described technical solution of the present invention has at least one of the following beneficial effects:

[0047] According to the online detection method for coating surface density of the present invention, the coating surface density is calculated by acquiring the electrode coating area S of the introduced electrode roll from the initial time t0 to the current time t1, as well as the initial electrode roll weight M0 at the initial time t0 and the current electrode roll weight M1 at the current time t1. Since the electrode coating area S can be determined by the winding speed and coating width, and the electrode roll weight can also be obtained through online detection, the online detection method for coating surface density of the present invention can achieve online detection of coating surface density without stopping the machine for sampling, thus improving the safety and detection efficiency of online coating surface density detection. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure for introducing the electrode roll into the electrode sheet at the tail of the coating machine;

[0049] Figure 2 This is a schematic diagram illustrating the principle of weight correction based on tension.

[0050] Figure reference numerals: 100. Polar roll; 110. Introduction section. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0052] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning understood by one of ordinary skill in the art to which this invention pertains. The terms "first," "second," and similar terms used in this invention do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, the terms "an" or "a" and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. The terms "connected" or "linked" and similar terms are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0053] The online detection method for coating surface density according to the first aspect of the present invention will be described in detail below.

[0054] The online detection method for coating surface density of this invention is applied to a battery coating machine.

[0055] According to some embodiments of the present invention, the online detection method for coating surface density includes the following steps:

[0056] S1, obtain the electrode coating area S of the introduced electrode roll from the initial time t0 to the current time t1;

[0057] S2, obtain the initial polar roll weight M0 at the initial time t0 and the current polar roll weight M1 at the current time t1 respectively;

[0058] S3. Calculate the coating density based on the initial electrode roll weight M0, the current electrode roll weight M1, and the electrode coating area.

[0059] In other words, the coating density can be calculated by obtaining the initial weight M0, the current weight M1, and the coating area of ​​the introduced electrode roll, which can improve the safety and efficiency of online coating density detection.

[0060] The electrode coating area S can be determined by the winding speed and coating width, eliminating the need for machine downtime for inspection. Furthermore, the electrode roll weight can also be obtained online, without requiring machine downtime. Therefore, the online detection method for coating surface density in this embodiment of the invention can achieve online detection of coating surface density without stopping the machine for sampling, and the detection process does not rely on X / β-ray surface density measurement equipment, offering advantages such as high safety and high detection efficiency.

[0061] In some embodiments, step S1 includes: determining the winding speed V; determining the time interval Δt based on the initial time t0 to the current time t1; obtaining the coating width L; and determining the electrode coating area S corresponding to the time interval Δt according to the following formula 1) based on the winding speed V, the time interval Δt, and the coating width L.

[0062] S=V*⊿t*L 1).

[0063] The winding speed V is uniquely determined by the winding mechanism, which typically operates at a constant speed. Therefore, it is sufficient to obtain the winding speed from the winding mechanism itself.

[0064] Furthermore, the coating width L is uniquely determined by the coating machine, and generally speaking, this coating width is constant.

[0065] In other words, once the time interval Δt (i.e., Δt = t1 - t0) is determined, the electrode length V*Δt within that time interval can be determined. Combined with the electrode width, i.e., the coating width L, the electrode coating area S introduced into the electrode roll 100 within that time interval can be obtained. Using this method to measure and calculate the electrode coating area S eliminates the need for machine downtime, improving the convenience and efficiency of online coating density detection.

[0066] To obtain the initial pole roll weight M0 and the current pole roll weight M1, for example, the weight can be directly measured from the initial time t0 to the current time t1 using a weighing unit located below the pole roll.

[0067] Once the electrode coating area S, the initial electrode roll weight M0, and the current electrode roll weight M1 are determined, the coating surface density can be calculated.

[0068] For example, when the time interval is short, the weight error caused by the tension applied to the electrode roll can be ignored, as can the weight error introduced by the substrate of the electrode sheet. In this case, the coating surface density can be estimated by (M1-M0) / S.

[0069] In some embodiments, step S3 includes:

[0070] S31, based on the initial polar roll weight M0 and the current polar roll weight M1, determine the polar roll weight difference ΔM corresponding to the time interval Δt, where ΔM=M1-M0;

[0071] S32, obtain the winding tension F, and determine the first weight change correction amount Δm1 based on the winding tension F;

[0072] S33, based on the polar roll weight change ΔM and the first weight change correction amount Δm1, the corrected weight difference ΔM' is obtained;

[0073] S34, Calculate the coating density ρ based on the corrected weight difference ΔM' and the electrode coating area S. m , where ρ m =⊿M' / S.

[0074] In other words, in this embodiment, the deviation in pole roll weight caused by winding tension F is corrected.

[0075] Specifically, by weighing the initial weight M0 of the electrode roll 100 at initial time t0 and the current weight M1 of the electrode roll at current time t1, the electrode roll weight difference ΔM = M1 - M0 within the time interval Δt is obtained. Furthermore, since the introduced portion 110 of the electrode roll 100 is subjected to the winding tension F during online weighing, and the vertical component of the winding tension F is one of the causes of weight deviation, the first weight change correction amount Δm1 is determined based on this winding tension F. This allows the obtained corrected electrode roll weight difference ΔM' within the time interval Δt. Finally, based on the corrected weight difference ΔM' and the electrode coating area S, the coating surface density ρ is calculated. m = ΔM' / S. By correcting the difference in electrode weight over the time interval Δt, the accuracy of coating surface density detection can be improved.

[0076] Among them, such as Figure 2 As shown, the winding tension F is typically a constant value. This winding tension F acts along the winding direction, therefore it can be decomposed into a horizontal component F2 and a vertical component F1, where the vertical component F1 is the cause of weight error. Therefore, by identifying the vertical component F1, the first weight change correction amount Δm1 caused by the winding tension F can be obtained. For example, F1 can be calculated by detecting the horizontal thrust F2 applied to the winding mechanism and combining it with the winding tension F.

[0077] In one embodiment, the radius of the polar roll is determined, and the included angle θ is determined by introducing a mapping relationship between the included angle θ between the portion 110 and the horizontal plane and the radius of the polar roll, thereby obtaining the vertical component F1, thereby determining the first weight change correction amount Δm1.

[0078] Below, in conjunction with Figure 2 Describe in detail the process of determining the first weight change correction amount Δm1.

[0079] In some implementations, step S32 includes:

[0080] S321, obtain the winding tension F.

[0081] The winding tension F is a constant value, usually a set value, which can be read directly from the winding device.

[0082] S322, obtain the polar radius R0 at the initial time t0 and the polar radius R1 at the current time t1.

[0083] Specifically, it can be measured, for example, using a thickness detection device, a distance detection sensor, and so on.

[0084] In some embodiments, for example, the distance between the center of the polar roll and the edge of the polar roll can be detected by a grating to determine the polar roll radius.

[0085] S323, based on the polar roll radii R1 and R0, the initial angle θ0 between the introduced part 110 of the polar roll 100 and the horizontal plane at the initial time t0 and the current angle θ1 at the current time are determined by the angle determination model.

[0086] In fact, such as Figure 2 As shown, there is a one-to-one correspondence between the polar radius R and the included angle θ. As long as the mapping relationship is determined in advance, that is, the angle determination model, the polar radius can be converted into the included angle θ through the angle determination model.

[0087] In some embodiments of this application, the angle determination model is determined as follows: the calibration pole roll radii at multiple different times are obtained, along with the corresponding calibration angle between the introduced portion 110 of the pole roll 100 and the horizontal plane; based on the multiple calibration pole roll radii and calibration angles, the angle determination model is obtained. That is, as... Figure 2 As shown, the change in the radius R of the polar roll will cause a change in the angle θ between the introduction part 110 of the polar roll 100 and the horizontal plane. Therefore, by setting different calibrated polar roll radii for each vehicle and the corresponding calibrated angle between the introduction part 110 and the horizontal plane, the functional relationship between the radius R of the polar roll and the angle θ between the introduction part 110 of the polar roll 100 and the horizontal plane can be obtained by fitting, thereby establishing an angle determination model.

[0088] It should be noted that this model can be determined using either continuous or discrete functions. Continuous functions provide more accurate values, while discrete functions reduce the workload. The appropriate choice between continuous and discrete functions can be made based on the specific accuracy requirements.

[0089] S324. Based on the winding tension F, the output angle θ0, and the current angle θ1, determine the first weight change correction amount Δm1, where the first weight change correction amount Δm1 = F(sinθ1-sinθ0) / g, and g is the gravitational acceleration.

[0090] In other words, based on the angle determination model, i.e., the mapping relationship between the polar roll radius and the included angle, the measured polar roll radius R0 at the initial time t0 and the polar roll radius R1 at the current time t1 can be transformed into the initial included angle θ0 between the introduced part 110 of the polar roll 100 and the horizontal plane at the initial time t0 and the current included angle θ1 at the current time. Then, by calculation, the difference F1 of the vertical component of the winding tension F at the initial time t0 and the current time t1 (that is, the first weight change correction amount Δm1) can be obtained. The vertical component of the winding tension F is F1 = F * sinθ, so the first weight change correction amount Δm1 in the time interval Δt can be calculated by the formula Δm1 = F(sinθ1 - sinθ0) / g.

[0091] The online detection method for coating surface density in this embodiment of the invention is based on the calibrated angle determination model. By obtaining the radius of the polar roll at a certain moment, the angle θ between the introduced part 110 of the polar roll 100 and the horizontal plane at that moment can be quickly obtained, and then the first weight change correction amount Δm1 within the time period Δt can be obtained, which can further improve the online detection efficiency of coating surface density.

[0092] Furthermore, section 110 includes the electrode sheet (i.e., the coating layer) and the substrate supporting the coating layer. The measured weight of the electrode roll also includes the weight of the substrate. This weight can be ignored when the time interval is sufficiently small, but to improve calculation accuracy, the weight needs to be corrected for the substrate portion.

[0093] In some embodiments of this application, S3 further includes:

[0094] S35, determine the second weight change correction amount Δm2=ρ*V*Δt*l for the substrate of the electrode sheet introduced into the electrode roll 100 from the initial time t0 to the current time t1, where l is the width of the substrate and ρ is the areal density of the substrate; wherein, in step S33, based on the weight change ΔM of the electrode roll, the first weight change correction amount Δm1, and the second weight change correction amount Δm2, the corrected weight difference ΔM'=ΔM+Δm1-Δm2 is obtained.

[0095] In other words, the weight of the substrate corresponding to the electrode sheet introduced into the electrode roll 100 needs to be used as the second weight change correction amount Δm2 for the weight difference within the time period Δt, in order to obtain the corrected weight difference. Specifically, the length of the substrate corresponding to the electrode sheet introduced into the electrode roll 100 is V*Δt, where V represents the winding speed, and the area of ​​the substrate corresponding to the electrode sheet introduced into the electrode roll 100 is V*Δt*l, where l is the width of the substrate. Thus, the weight of the substrate corresponding to the electrode sheet introduced into the electrode roll 100 is Δm2 = ρ*V*Δt*l, where ρ is the areal density of the substrate. Based on the calculated second weight change correction amount Δm2 for the weight difference within the time period Δt, combined with the first weight change correction amount Δm1 in step S33, the corrected weight difference ΔM' within the time period Δt can be further obtained as ΔM + Δm1 - Δm2. In other words, by calculating the second weight change correction amount Δm2 of the substrate of the electrode introduced into the electrode roll 100, the weight difference within the time period Δt is corrected, thereby further improving the detection accuracy of the coating surface density.

[0096] Furthermore, when Δt is less than a predetermined value, the coating surface density ρ is determined by the following formula 2). m ρ m = [(⊿M-⊿m2] / (V*⊿t*L). That is, when ⊿t is less than a predetermined value, i.e., when this predetermined value is taken, the change in radius of the electrode roll 100 within the time period ⊿t is very small, the change in the angle θ between the introduction portion 110 of the electrode roll 100 and the horizontal plane is also very small, and thus the change in the vertical component of the winding tension F is also very small. Consequently, the first weight change correction amount ⊿m1 = F(sinθ1-sinθ0) / g can be ignored. In other words, the corrected weight difference within the time period ⊿t is ⊿M-ρ*V⊿t*l, which is ⊿M-⊿m2. That is to say, when detecting coating surface density in a short time, the change in the vertical component of the winding tension F caused by the change in the radius of the electrode roll 100 can be ignored, thereby simplifying the calculation and further improving the online detection efficiency of coating surface density.

[0097] According to a second aspect of the present invention, an online coating surface density detection device is applied to a battery coating machine, comprising a weighing unit and a calculation unit. The weighing unit is disposed below the winding device of the battery coating machine to weigh the electrode roll 100. The calculation unit determines the coating surface density based on the coating speed, coating width, and the difference in electrode roll weight at different times. That is, when performing online detection of coating surface density, the online coating surface density detection device first obtains the initial electrode roll weight M0 at initial time t0 and the current electrode roll weight M1 at current time t1 through the weighing unit. Then, the calculation unit determines the coating surface density based on the coating speed, coating width, and the difference in electrode roll weight at different times ΔM = M1 - M0.

[0098] The online coating surface density detection device of this invention does not require stopping the equipment for sampling, and the online detection of coating surface density can be achieved without relying on radiation detection equipment such as X / β-ray surface density measuring instruments during the detection process. This online coating surface density detection device has the advantage of high safety.

[0099] Furthermore, the online coating surface density detection device also includes a thickness detection unit, which is used to detect the radius of the electrode roll 100. The calculation unit determines the model by angle determination, determines the angle between the lead-in portion 110 of the electrode roll 100 and the horizontal plane based on the radius, and determines the first weight correction amount based on the angle and the winding tension. After correcting the difference in electrode roll weight based on the first weight correction amount, the coating surface density is calculated. In other words, in order to determine the first weight correction amount Δm1, the polar roll radius R0 at the initial time t0 and the polar roll radius R1 at the current time t1 are first detected by the weight correction unit. Then, the calculation unit determines the model by angle. Based on the polar roll radius R0 at the initial time t0 and the polar roll radius R1 at the current time t1, the angles θ0 and θ1 between the introduced part 110 of the polar roll 100 and the horizontal plane at the initial time t0 and the current time t1, respectively, are determined. Thus, the first weight correction amount Δm1 = F(sinθ1-sinθ0) / g is obtained. This online coating surface density detection device has the advantage of high detection accuracy.

[0100] To facilitate measurement and simplify calculation, the initial time t0 can be selected before the coating machine starts, at which point the coating machine is in a stopped state. This allows for accurate and convenient measurement of the original radius and weight of the electrode roll 100, thereby obtaining the angle θ between the introduced part 110 of the electrode roll 100 and the horizontal plane. Substituting this into the formula Δm1=F(sinθ1-sinθ0) / g, the first weight correction amount Δm1 can be obtained, which can further improve detection efficiency and accuracy.

[0101] In addition, to enable online monitoring, measurements can be taken at predetermined time intervals, allowing for timely adjustments to coating parameters based on the measurement results, which can effectively reduce the scrap rate caused by coating abnormalities.

[0102] According to a third aspect of the present invention, a battery coating apparatus includes a battery coating machine and the aforementioned online coating density detection device. That is, by using the aforementioned online coating density detection device on the battery coating machine, online detection of the coating density can be achieved. Furthermore, this online coating density detection device does not emit radiation and has the advantages of high detection efficiency and good safety.

[0103] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An online method for detecting coating surface density, applied to a battery coating machine, characterized in that, Includes the following steps: S1, obtain the time interval Δt from the initial time t0 to the current time t1, and introduce the electrode coating area S of the electrode roll; S2, obtain the initial polar roll weight M0 at the initial time t0 and the current polar roll weight M1 at the current time t1 respectively; S3, calculate the coating density based on the initial electrode roll weight M0, the current electrode roll weight M1, and the electrode coating area; Step S3 includes: S31, based on the initial polar roll weight M0 and the current polar roll weight M1, determine the polar roll weight difference ΔM corresponding to the time interval Δt, where ΔM = M1 - M0; S32, obtain the winding tension F, and determine the first weight change correction amount Δm1 based on the winding tension F; S33, based on the polar roll weight difference ΔM and the first weight change correction amount Δm1, the corrected weight difference ΔM' is obtained; S34, Calculate the coating surface density ρ based on the corrected weight difference ΔM' and the electrode coating area S. m , where ρ m= ⊿M' / S; Step S32 includes: S321, Obtain the winding tension F; S322, obtain the polar radius R0 at the initial time t0 and the polar radius R1 at the current time t1; S323, based on the polar roll radii R1 and R0, the initial angle θ0 between the introduced part of the polar roll and the horizontal plane at the initial time t0 and the current angle θ1 at the current time are determined by the angle determination model. S324, based on the winding tension F, the output angle θ0, and the current angle θ1, determine the first weight change correction amount Δm1, where the first weight change correction amount Δm1 = F(sinθ1-sinθ0) / g, and g is the gravitational acceleration.

2. The online detection method for coating surface density according to claim 1, characterized in that, Step S1 includes: Determine the winding speed V; Based on the initial time t0 to the current time t1, determine the time interval Δt; Obtain the coating width L; Based on the winding speed V, the time interval Δt, and the coating width L, the electrode coating area S corresponding to the time interval Δt is determined according to the following formula 1). S=V*⊿t*L 1).

3. The online detection method for coating surface density according to claim 1, characterized in that, The angle determination model is determined as follows: The calibration radius of the polar roll at multiple different times, and the corresponding calibration angle between the introduced part of the polar roll and the horizontal plane, were obtained respectively. The angle determination model is obtained based on the multiple calibration polar radius and calibration angle.

4. The online detection method for coating surface density according to claim 1, characterized in that, Step S3 further includes: S35, determine the second weight change correction amount Δm2=ρ*V*Δt*l of the substrate of the electrode sheet introduced into the electrode roll from the initial time t0 to the current time t1, where l is the width of the substrate and ρ is the areal density of the substrate. In step S33, the corrected weight difference ΔM' = ΔM + Δm1 - Δm2 is obtained based on the polar roll weight change ΔM, the first weight change correction amount Δm1, and the second weight change correction amount Δm2.

5. The online detection method for coating surface density according to claim 4, characterized in that, When the Δt is less than a predetermined value, the coating surface density ρ is determined by the following formula 2). m : r m =[(⊿M-⊿m2] / (V*⊿t*L) 2).

6. An online detection device for coating surface density, applied to a battery coating machine, characterized in that, For detecting coating surface density using the online coating surface density detection method according to any one of claims 1-5, comprising: A weighing unit is provided, which is disposed below the winding device of the battery coating machine to weigh the electrode roll. The calculation unit calculates the coating surface density based on the coating speed, coating width, and the difference in the weight of the electrode roll at different times.

7. The online coating density detection device according to claim 6, characterized in that, Also includes: A thickness detection unit, which is used to detect the radius of the electrode roll; The calculation unit determines the angle between the introduced portion of the electrode roll and the horizontal plane based on the radius using an angle determination model. Based on the angle and the winding tension, it determines a first weight correction amount. After correcting the difference in the weight of the electrode roll based on the first weight correction amount, it calculates the coating surface density.

8. The online coating surface density detection device according to claim 6, characterized in that, Also includes: An early warning unit receives the coating surface density calculated by the calculation unit and issues an early warning when the coating surface density exceeds a predetermined threshold range.

9. A battery coating apparatus, characterized in that, include: Battery coating machine; as well as The online coating surface density detection device according to any one of claims 6 to 8.

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