Method for detecting wettability of electrolyte and application thereof

Abstract

The invention belongs to the technical field of batteries, and particularly relates to an electrolyte wettability detection method and application thereof.The electrolyte wettability detection method comprises the steps that a powder tablet containing an electrode material is prepared; adhering adhesive paper to one side of the powder tablet to obtain a sample; the sample is placed on a transparent plate, and the face, back to the gummed paper, of the powder tablet abuts against the transparent plate; dropping electrolyte on the upper surface of the powder tablet, and recording the infiltration time of the electrolyte from the upper surface of the powder tablet to the lower surface of the powder tablet and the color change of the lower surface of the powder tablet in the infiltration process; calculating the infiltration rate of the electrolyte by using the thickness of the powder tablet and the infiltration time; the method is relatively simple and convenient to operate, does not need complex equipment and instruments, is more visual and accurate compared with a traditional contact angle measurement method, an infiltration height method and the like, and can quickly evaluate the infiltration performance of the electrolyte.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a detection method for the wettability of an electrolyte and its application. Background Art

[0002] As a new type of secondary battery, lithium-ion batteries have the advantages of high energy density and power density, high working voltage, light weight, small size, long cycle life, good safety, environmental friendliness, etc., and have broad application prospects in portable electrical appliances, electric tools, large-scale energy storage, electric vehicle power sources, etc.

[0003] In order to improve the energy density of lithium-ion batteries, it has become a common practice to use positive and negative electrode materials with high capacity and high tap density. However, when injecting the electrolyte into such electrodes with high tap density, the absorption rate of the electrolyte will be slowed down, and it may cause uneven distribution of the electrolyte inside the battery, which in turn leads to problems such as a decrease in battery capacity, an increase in internal resistance, and a shortening of service life. In addition, poor electrode wettability will also prolong the battery filling process and reduce production efficiency. Therefore, good wettability of the electrolyte is crucial for ensuring effective contact of internal components of the battery, and directly affects ion conduction efficiency, battery safety, and cycle life.

[0004] However, in the prior art, the methods for evaluating the wettability of the electrolyte generally have problems such as complex operation, long test cycle, and high cost. Summary of the Invention

[0005] The purpose of the present invention is to provide a detection method for the wettability of an electrolyte and its application, aiming at the deficiencies of the prior art, and solving the technical problems that the methods for evaluating the wettability of the electrolyte in the prior art generally have complex operation, long test cycle, and high cost.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a detection method for the wettability of an electrolyte, and the detection method includes:

[0008] Preparing a powder tablet containing electrode material;

[0009] Pasting adhesive tape on one side of the powder tablet to obtain a sample;

[0010] Placing the sample on a transparent plate, and the side of the powder tablet facing away from the adhesive tape is in contact with the transparent plate;

[0011] Dropping the electrolyte on the upper surface of the powder tablet, and recording the infiltration time of the electrolyte from the upper surface of the powder tablet to the lower surface of the powder tablet and the color change of the lower surface of the powder tablet (1) during the infiltration process;

[0012] Calculate the infiltration rate of the electrolyte using the thickness of the powder tablet and the infiltration time.

[0013] In some embodiments, the method for preparing the tablet includes:

[0014] Mix and stir the electrode material powder, binder, and solvent to form a slurry;

[0015] Coat the slurry on the surface of the foil and dry the slurry;

[0016] After drying, peel the slurry from the foil and grind and screen the slurry to obtain a tablet material with uniform particles;

[0017] Press the weighed tablet material to obtain the powder tablet.

[0018] In some embodiments, place the slurry coated on the surface of the foil in a forced-air drying oven for drying, wherein the drying temperature is 95°C to 115°C and the drying time is 20 to 30 min.

[0019] In some embodiments, the screen mesh number of the ground slurry is 80 to 120 mesh.

[0020] In some embodiments, before drying the slurry, the mass ratio of the electrode material powder, the binder, and the solvent is 7:(0.2 to 0.4):(9.6 to 9.8).

[0021] In some embodiments, the center of the adhesive tape has a through hole, and the electrolyte is dropped on the upper surface of the powder tablet through the through hole, and the center of the through hole and the center of the powder tablet are on the same axis.

[0022] In some embodiments, the area S1 of the through hole and the area S2 of the upper surface of the powder tablet satisfy the relationship:

[0023] In some embodiments, the detection method further includes:

[0024] Immerse the infiltrated sample in a beaker filled with electrolyte for 1 to 3 min;

[0025] After soaking, remove the electrolyte not absorbed by the surface of the sample, weigh it, and calculate the liquid absorption of the sample;

[0026] Among them, the liquid absorption capacity L of the powder tablet satisfies the relational expression: L = G3 - (G1 + G2), where G1 is the weight of the powder tablet before infiltration, G2 is the weight of the adhesive tape, and G3 is the weight of the sample after soaking.

[0027] In some embodiments, a camera is installed at the bottom of the transparent plate, and the infiltration time taken by the electrolyte from the upper surface to the lower surface of the powder tablet is recorded by the camera.

[0028] In a second aspect, the present invention provides an application of the detection method for the wettability of the electrolyte in the above embodiments, and the detection method is applied to the field of lithium-ion batteries.

[0029] Compared with the prior art, the beneficial effects achieved by the present invention are as follows:

[0030] The detection method for the wettability of the electrolyte in the embodiments of the present invention obtains a sample to be infiltrated by preparing a powder tablet containing an electrode material and pasting an adhesive tape on one side thereof. The infiltration process of the electrolyte in the powder material is effectively amplified, facilitating the recording and observation of the infiltration process of the electrolyte in the powder tablet. The operation is relatively simple, without the need for complex equipment and instruments. It only requires placing the sample on the transparent plate and recording the infiltration process. This method is more intuitive and accurate compared to traditional contact angle measurement methods, infiltration height methods, etc. At the same time, by calculating the infiltration rate, the infiltration performance of the electrolyte can be quickly evaluated.

[0031] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. Description of the Drawings

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 It is a schematic flow chart of the present invention.

[0034] Figure 2 It is one of the schematic structural diagrams of the powder tablet of the present invention.

[0035] Figure 3 It is the second schematic structural diagram of the powder tablet of the present invention.

[0036] Among them, the descriptions of the reference numerals are as follows:

[0037] 1. Powder pressing; 2. Adhesive tape; 21. Through hole; 3. Transparent plate. Detailed implementation mode

[0038] As used in the specification and claims, certain terms are used to refer to specific components. Those skilled in the art should understand that hardware manufacturers may use different terms to refer to the same component. The specification and claims do not use the difference in names as a way to distinguish components, but use the difference in functions of components as the criterion for distinction. As mentioned throughout the specification and claims, "including" is an open-ended term and should be interpreted as "including but not limited to". "Roughly" means within an acceptable error range. Those skilled in the art can solve technical problems within a certain error range and basically achieve technical effects.

[0039] In addition, terms such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0040] In the invention, unless otherwise clearly specified and limited, terms such as "installation", "connection", "connection", "fixation", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0041] Next, in combination with the attached Figure 1 The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0042] In the prior art, common methods for evaluating the wettability of electrolytes include the contact angle measurement method, the wetting height method, and the wetting mass measurement method (also known as the wetting balance method). The contact angle measurement method judges the wetting ability by observing the size of the contact angle formed by the electrolyte drop on the solid surface. The wetting height method evaluates the wettability by partially or completely immersing a solid material (such as a separator) with specific dimensions in the electrolyte and measuring the weight change of the material absorbing the electrolyte over a period of time. The wetting balance method (wetting mass measurement method) records the change in the rising height of the electrolyte and the initial mass when the electrode sheet is suspended below the balance.

[0043] However, the inventors found that although the existing methods for evaluating electrolyte wettability are relatively mature, there are still some limitations and deficiencies. For example, the contact angle measurement method is susceptible to the influence of the roughness and non-uniformity of the solid surface, which may lead to the contact angle hysteresis phenomenon, thus affecting the accuracy of wettability evaluation. Moreover, the contact angle measurement method also depends on the operator's skills and experience because the determination of the contact angle has a certain subjectivity.

[0044] The wetted height method needs to measure the weight change of the material absorbing the electrolyte over a period of time. Therefore, the test cycle is usually long and not suitable for rapid evaluation. Moreover, during the test process, it is necessary to precisely control the immersion depth and measurement time, increasing the complexity of the operation.

[0045] The results of the wetting balance method (wetted mass measurement method) are susceptible to the interference of electrolyte characteristics (such as density, viscosity, etc.), which may affect the accuracy of wettability evaluation. Moreover, the accuracy of the wetting balance method depends on the precision and stability of the balance. Therefore, the quality and calibration status of the equipment have an important impact on the test results.

[0046] In view of this, the present invention provides a method for detecting the wettability of an electrolyte, which includes:

[0047] Preparing a powder tablet 1 containing an electrode material;

[0048] Sticking adhesive tape 2 on one side of the powder tablet 1 to obtain a sample;

[0049] Placing the sample on a transparent plate 3, and the side of the powder tablet 1 opposite to the adhesive tape 2 abuts against the transparent plate 3;

[0050] Dropping the electrolyte on the upper surface of the powder tablet 1, and recording the infiltration time taken by the electrolyte from the upper surface of the powder tablet 1 to the lower surface of the powder tablet 1 and the color change of the lower surface of the powder tablet 1 during the infiltration process;

[0051] Calculating the infiltration rate of the electrolyte by using the thickness of the powder tablet 1 and the infiltration time.

[0052] Compared with the prior art, the method for detecting the electrolyte wettability in the embodiments of the present invention obtains a sample to be wetted by preparing a powder tablet 1 containing an electrode material and pasting adhesive tape 2 on one side thereof. It effectively magnifies the wetting process of the electrolyte in the powder material, facilitating the recording and observation of the wetting process of the electrolyte in the powder tablet 1. The operation is relatively simple, without the need for complex equipment and instruments. One only needs to place the sample on a transparent plate 3 and record the wetting process. This method is more intuitive and accurate compared to traditional contact angle measurement methods, wetting height methods, etc. At the same time, by calculating the wetting rate, the wetting performance of the electrolyte can be quickly evaluated. In addition, since the electrolyte is dropped on the upper surface of the powder tablet 1, when the electrolyte penetrates to the lower surface of the powder tablet 1, the color of the lower surface of the powder tablet 1 will gradually change from light to dark. Therefore, by recording the color change of the lower surface of the powder tablet 1 and through the starting time of the color change and the color gradient speed, the penetration rate of the electrolyte in the powder tablet 1 can be quantitatively analyzed. A faster color change speed and a uniform color distribution usually mean better penetration performance, which helps to ensure sufficient contact and reaction between the electrolyte and the powder tablet 1.

[0053] It can be understood that the wetting rate V of the electrolyte is equal to the thickness H of the powder tablet 1 divided by the wetting time T, that is

[0054] In some embodiments, a camera is installed at the bottom of the transparent plate 3, and the wetting time taken by the electrolyte from the upper surface of the powder tablet 1 to the lower surface of the powder tablet 1 is recorded by the camera. By using a camera to record the wetting process and calculate the wetting rate, it can more accurately reflect the wetting performance of the electrolyte compared to methods such as simply observing with the naked eye or measuring the wetting height. Under the same experimental conditions, for samples of the same batch, this detection method can obtain relatively consistent detection results, thereby improving the repeatability and reliability of the experiment.

[0055] It can be understood that the transparent plate 3 is a glass plate. The glass plate has excellent optical transparency, making the wetting process of the electrolyte on the powder tablet 1 clearly visible. The glass plate has excellent chemical stability and can resist the corrosive effect of the electrolyte. This ensures that the glass plate will not deform or break due to the erosion of the electrolyte during the test process, thus guaranteeing the accuracy and reliability of the test.

[0056] In some embodiments, a quantitatively extracted electrolyte is dropped on the upper surface of the powder tablet 1 through the through hole 21 by a pipette. As a precise liquid handling tool, the pipette can ensure the quantitative extraction and accurate dropping of the electrolyte, and can reduce the influence on the experimental results caused by uneven addition of the electrolyte.

[0057] In some embodiments, the method for preparing the powder tablet 1 includes:

[0058] Mix the electrode material powder, binder, and solvent and stir to form a slurry;

[0059] Coat the slurry on the surface of the foil and dry the slurry;

[0060] After drying is completed, peel the slurry from the foil, and grind and screen the slurry to obtain a tablet material with uniform particles;

[0061] Press the weighed tablet material to obtain a powder tablet 1.

[0062] For the prepared powder tablet 1, only a small amount of binder is used. By drying the slurry coated on the surface of the foil, the solvent is effectively removed, the slurry is cured, and the influences of the binder, conductive agent, dispersant, and other factors in the preparation process of the electrode sheet and the wound core are excluded, reducing the test difficulty and excluding the influence of the solvent on the detection result of the electrolyte wettability.

[0063] After peeling the dried slurry from the foil and then grinding and screening it, a tablet material with uniform particles can be obtained. After pressing, the powder tablet 1 has a high tap density. The powder tablet 1 with a high tap density can more realistically simulate the actual state of the positive and negative electrode materials inside the battery, thus improving the accuracy of the detection. By detecting the wettability of the electrolyte of this tablet material with a high tap density, the wettability of the electrolyte of the battery can be evaluated more accurately. Since the particle size of the tablet material is uniform and small, the consistency of the pore size and distribution inside the powder tablet 1 helps to achieve uniform wetting of the electrolyte. Due to the consistency of the pore size and distribution, the electrolyte is evenly distributed and rapidly penetrates inside the powder tablet 1, avoiding problems of local insufficient wetting or over-wetting caused by uneven pore sizes. At the same time, the change in capillary force caused by the difference in pore size is reduced. This reduced influence of the capillary effect makes the wetting of the electrolyte inside the powder tablet 1 more stable and controllable, thereby reducing the influence of the uneven particles of the tablet material on the detection result of the electrolyte wettability.

[0064] It can be understood that the foil is a copper foil, and the chemical properties of the copper foil are relatively stable and it is not easy to react with other chemical substances. It can effectively prevent the slurry from reacting with the copper foil, resulting in affecting the accuracy of subsequent detection results.

[0065] In some embodiments, the slurry coated on the surface of the foil is placed in a forced-air drying oven for drying. Among them, the drying temperature is 95°C to 115°C, and the drying time is 20 to 30 minutes. Through the setting of the drying temperature, the drying temperature cannot be too high or too low. When the drying temperature is too high, that is, when the drying temperature is greater than 115°C, the slurry is prone to denaturation or charring due to excessive temperature. When the drying temperature is too low, that is, when the drying temperature is less than 95°C, the drying time of the slurry is prone to be too long due to low temperature, affecting the drying efficiency. Therefore, setting the drying temperature to 95°C to 115°C not only ensures the rapid volatilization of the solvent in the slurry but also avoids the denaturation or charring of the material due to excessive temperature. This temperature range can achieve the best balance between drying efficiency and material protection.

[0066] Through the setting of the drying time, the drying time cannot be too long or too short. When the drying time is too long, that is, when the drying time is greater than 30 minutes, the slurry is prone to over-baking and denaturation or charring. When the drying time is too short, that is, when the drying time is less than 20 minutes, the drying time of the slurry is insufficient, resulting in partial solvent residue, affecting the subsequent test results. Therefore, setting the drying time to 20 to 30 minutes effectively avoids the denaturation or charring of the slurry due to over-drying and also avoids partial solvent residue due to insufficient drying time.

[0067] At the same time, setting the drying temperature to 95°C to 115°C and the drying time to 20 to 30 minutes can effectively balance the drying quality and drying efficiency, ensuring that within this temperature range and time range, the solvent in the slurry can volatilize rapidly, while ensuring the quality of the dried slurry.

[0068] In addition, the hot air in the forced-air drying oven can evenly blow the slurry coated on the surface of the foil, ensuring that all parts are fully dried and ensuring the drying quality of the slurry.

[0069] In some embodiments, the drying temperature is 95°C, 96°C, 99°C, 100°C, 103°C, 105°C, 110°C, 112°C or 115°C. However, it is not limited to the listed values, and other values within the numerical range are equally applicable.

[0070] The drying time is 20 minutes, 21 minutes, 22 minutes, 23 minutes, 24 minutes, 25 minutes, 26 minutes, 27 minutes, 28 minutes, 29 minutes or 30 minutes. However, it is not limited to the listed values, and other values within the numerical range are equally applicable.

[0071] Preferably, the drying temperature is 105°C and the drying time is 30 min. The high temperature of 105°C can effectively promote the rapid evaporation of the solvent, enabling the solvent in the slurry to be removed within 30 min, avoiding solvent residues and ensuring the quality of the dried slurry. At the same time, although the drying temperature of 105°C is relatively high, the drying time of 30 min is relatively short, so the overall energy consumption is still controllable. Compared with long-time low-temperature drying, this drying method is more energy-efficient.

[0072] In some embodiments, the screening mesh number of the ground slurry is 80 - 120 meshes. By setting the screening mesh number of the ground slurry, the screening mesh number of the ground slurry should not be too large or too small. When the screening mesh number of the ground slurry is too large, that is, the screening mesh number of the ground slurry is greater than 120 meshes, an increase in the screening mesh number means that the holes in the sieve mesh are finer, which will lead to an increase in the resistance during the screening process, reducing the screening efficiency. At the same time, the fine sieve mesh holes are more likely to be blocked, requiring more frequent cleaning and maintenance, further reducing the screening efficiency. In addition, too large a screening mesh number may result in overly fine particles in the slurry, and the fine particles are more likely to form aggregates. Aggregation causes the surface of the tablet pressing material to become rough and uneven, increasing the difficulty of contact between the electrolyte and the electrode material. At the same time, the pore structure inside the aggregates may cause some micropores to not be effectively wetted by the electrolyte, thereby reducing the effective contact area between the electrolyte and the electrode material, and further affecting the subsequent detection results of the electrolyte wettability. When the screening mesh number of the ground slurry is too small, that is, the screening mesh number of the ground slurry is less than 80 meshes, too small a screening mesh number means that the particles in the slurry are larger and unevenly distributed. This will result in larger gaps between the particles during the pressing process, making it difficult to form a dense packing structure, which will lead to a decrease in the compaction density of the tablet pressing, making it impossible to form a powder tablet pressing 1 with a high compaction density, and thus the powder tablet pressing 1 cannot more realistically simulate the actual state of the positive and negative electrode materials inside the battery, reducing the accuracy of the detection and being unable to accurately evaluate the wettability of the battery electrolyte. At the same time, too small a screening mesh number may require more grinding and screening steps during the preparation process to remove larger particles and obtain a more uniform particle distribution. This will increase the production cost and time cost and reduce the efficiency.

[0073] Therefore, by setting the screening mesh size of the ground slurry to 80 - 120 mesh, within this range, the particle size of the tablet pressing material is moderate and evenly distributed. This is conducive to forming a tight packing structure during the pressing process, thereby improving the compaction density of the tablet. A tablet with a high compaction density can more realistically simulate the actual state of the positive and negative electrode materials inside the battery, and thus enhance the accuracy of electrolyte wettability detection. At the same time, the uniform particle distribution can also reduce the formation of aggregates, avoiding problems such as rough surfaces and reduced electrolyte wettability caused by aggregation. In addition, within this range, the resistance during the screening process can be reduced, improving the screening efficiency. Compared with the situation where the screening mesh size is too large or too small, the holes in the 80 - 120 mesh sieve are neither easily blocked nor can effectively remove the particles that do not meet the requirements. And there is no need for excessive grinding and screening steps to remove larger particles or obtain a more uniform particle distribution, so the production cost and time cost can be reduced. This helps to improve the preparation efficiency of the powder tablet 1,

[0074] In some embodiments, the screening mesh size of the ground slurry is 80 mesh, 85 mesh, 90 mesh, 95 mesh, 100 mesh, 105 mesh, 110 mesh, 115 mesh or 120 mesh. However, it is not limited to the listed values, and other values within the numerical range are equally applicable.

[0075] In some embodiments, before the slurry is dried, the mass ratio of the electrode material powder, the binder, and the solvent is 7:(0.2 - 0.4):(9.6 - 9.8). By setting the mass ratio of the electrode material, the binder, and the solvent to 7:(0.2 - 0.4):(9.6 - 9.8), at this ratio, the electrode material powder, the binder, and the solvent can be fully mixed to ensure that the powder particles are evenly dispersed in the solvent. At the same time, since the proportion of the electrode material powder is relatively high and the proportion of the binder is relatively low, and the solvent is removed after drying, the influence of other conductive agents, binders, and dispersants is effectively excluded, and only the ease of electrolyte wetting of the electrode material is studied, thus simplifying the problem and improving the accuracy of the analysis.

[0076] In some embodiments, the mass ratio of the electrode material powder, the binder, and the solvent is 7:0.2:9.8, 7:0.3:9.7 or 7:0.4:9.6. However, it is not limited to the listed values, and other values within the numerical range are equally applicable.

[0077] In some embodiments, the center of the adhesive tape 2 has a through-hole, and the electrolyte is dropped onto the upper surface of the powder compact 1 through the through-hole 21. The center of the through-hole 21 and the center of the powder compact 1 are located on the same axis. By providing the through-hole 21 at the center of the adhesive tape 2, this structure not only ensures that the electrolyte can be dropped onto the upper surface of the powder compact 1 through the through-hole 21, but also ensures that the wetting position of the electrolyte is more accurate and controllable. By aligning the center of the through-hole 21 with the center of the powder compact 1, it is ensured that the electrolyte can be dropped at the center of the powder compact 1, thereby ensuring the uniform distribution of the electrolyte in the powder compact 1 and the uniform flow of current in the powder compact 1. This helps to obtain more accurate and reliable test results, providing strong support for the evaluation and optimization of the wettability of the electrolyte.

[0078] In some embodiments, the area S1 of the through-hole 21 and the area S2 of the upper surface of the powder compact 1 satisfy the relationship: By setting the area S1 of the through-hole 21 and the area S2 of the upper surface of the powder compact 1, the area ratio of the through-hole 21 to the upper surface of the powder compact 1 should not be too large or too small. When the area ratio of the through-hole 21 to the upper surface of the powder compact 1 is too small, i.e., , the area of the through-hole 21 is small, which may limit the flow of the electrolyte. The speed at which the electrolyte penetrates into the powder compact 1 through the through-hole 21 will slow down, which will limit the wettability of the electrolyte and affect the subsequent test results, reducing the accuracy of the test results. When the area ratio of the through-hole 21 to the upper surface of the powder compact 1 is too large, i.e., , the large area of the through-hole 21 results in a smaller contact area between the adhesive tape 2 and the powder compact 1, making the restraint of the adhesive tape 2 on the powder compact 1 poor. Thus, during the wetting process of the electrolyte, the powder compact 1 is prone to scatter, affecting the subsequent test results and reducing the accuracy of the test results.

[0079] Therefore, the area S1 of the through-hole 21 and the area S2 of the upper surface of the powder compact 1 satisfy the relationship: This can maintain the structural integrity of the powder compact 1 while ensuring effective wetting of the electrolyte, providing accurate and reliable test results for the evaluation of battery performance.

[0080] In some embodiments, the detection method further includes:

[0081] Immersing the sample after the wetting treatment into a beaker filled with electrolyte for 1 - 3 minutes;

[0082] After the immersion, removing the electrolyte on the surface of the sample that has not been absorbed by the sample, weighing it, and calculating the liquid absorption of the sample;

[0083] Among them, the liquid absorption capacity L of the powder tablet 1 satisfies the relational expression: L = G3 - (G1 + G2), where G1 is the weight of the powder tablet 1 before infiltration, G2 is the weight of the adhesive tape 2, and G3 is the weight of the sample after soaking.

[0084] By immersing the sample after the infiltration treatment into a beaker filled with electrolyte, the absorption capacity of the powder tablet 1 for the electrolyte is calculated, so as to understand the performance of the powder tablets 1 of different materials in the electrolyte, and provide reference data for the subsequent battery design. The calculation formula of the liquid absorption capacity L, L = G3 - (G1 + G2), directly relates to the mass change of the powder tablet 1 before and after infiltration, excluding the influence of the weight of the adhesive tape 2, making the evaluation result more accurate. This helps to distinguish the influence of different materials or preparation processes on the electrolyte absorption capacity, and provides a favorable basis for material screening and performance optimization.

[0085] In addition, by setting the soaking time to 1 - 3 minutes, it not only ensures that the electrolyte fully infiltrates the powder tablet 1, but also prevents the electrolyte from excessively penetrating or the material structure from being damaged due to too long soaking time. Effectively optimize the infiltration conditions to ensure the accuracy and repeatability of the detection results.

[0086] In some embodiments, the electrode material powder is a positive electrode material powder or a negative electrode material powder; the positive electrode material powder is one or more of lithium cobaltate, lithium manganate, lithium iron phosphate, nickel cobalt manganese ternary material, and nickel cobalt aluminum ternary material; the negative electrode material powder is one or more of carbon materials and alloy materials; the binder is one or more of polyacrylic acid, polyvinylidene fluoride, styrene-butadiene rubber, and polytetrafluoroethylene. Effectively ensure the diversity of the selection of the positive electrode material, negative electrode material, and binder, and facilitate the selection of the positive electrode material, negative electrode material, and binder according to actual needs.

[0087] In some embodiments, the carbon material is one or more of natural graphite, artificial graphite, mesocarbon microbeads (MCMB), hard carbon, and soft carbon. The alloy material is one or more of alloy materials composed of at least two of silicon, chromium, tin, lead, and antimony.

[0088] The present invention provides an application of the detection method for the wettability of the electrolyte in the above embodiments, and the detection method is applied to the field of lithium-ion batteries.

[0089] Through the detection method of the above embodiments, the infiltration situation of the electrolyte in the lithium-ion battery materials can be accurately measured, and the liquid absorption efficiency and the electrolyte distribution uniformity of the battery materials can be evaluated more accurately, so as to predict the actual performance of the battery. Through this test method, the electrolyte infiltration ability and the absorption ability of different electrode materials for the electrolyte can be distinguished, and reference data can be provided for the optimization of the battery structure, the improvement of the battery energy density, and the cycle performance of the battery.

[0090] The technical solution of the present invention will be described below through specific embodiments.

[0091] Example 1:

[0092] A test method for the wettability of the electrolyte, the detection method comprising:

[0093] Preparing a powder tablet 1 containing an electrode material;

[0094] Sticking an adhesive tape 2 on one side of the powder tablet 1 to obtain a sample, the center of the adhesive tape 2 having a through hole 21;

[0095] Placing the sample on a transparent plate 3, the side of the powder tablet 1 facing away from the adhesive tape 2 being in contact with the transparent plate 3, and installing a camera at the bottom of the transparent plate 3;

[0096] Dropping the electrolyte onto the upper surface of the powder tablet 1 through the through hole 21, and recording, by means of the camera, the wetting time taken for the electrolyte to reach the lower surface of the powder tablet 1 from the upper surface of the powder tablet 1;

[0097] Calculating the wetting rate of the electrolyte by using the thickness of the powder tablet 1 and the wetting time;

[0098] Wherein, the electrode material is a negative electrode material powder, the negative electrode material powder is graphite, the thickness of the powder tablet 1 is 2.19 mm, and the compaction density of the powder tablet 1 is 1.29 g / cm 3 , and the wetting time of the powder tablet 1 is 8 s.

[0099] Example 2:

[0100] Differing from Example 1, the thickness of the powder tablet 1 is 1.74 mm, and the compaction density of the powder tablet 1 is 1.61 g / cm 3 , and the wetting time of the powder tablet 1 is 15 s.

[0101] Example 3:

[0102] Differing from Example 1, the thickness of the powder tablet 1 is 1.20 mm, and the compaction density of the powder tablet 1 is 1.45 g / cm 3 , and the wetting time of the powder tablet 1 is 12 s.

[0103] Example 4:

[0104] Differing from Example 1, the thickness of the powder tablet 1 is 2.50 mm, and the compaction density of the powder tablet 1 is 1.15 g / cm 3 , and the wetting time of the powder tablet 1 is 10 s.

[0105] Example 5:

[0106] Different from Example 1, the electrode material is a cathode material, the cathode material powder is lithium iron phosphate, the thickness of Powder Tablet 1 is 1.42 mm, and the tap density of Powder Tablet 1 is 1.97 g / cm 3 , and the infiltration time of Powder Tablet 1 is 39 s.

[0107] Example 6:

[0108] Different from Example 5, the thickness of Powder Tablet 1 is 2.91 mm, and the tap density of Powder Tablet 1 is 1.29 g / cm 3 , and the infiltration time of Powder Tablet 1 is 39 s.

[0109] Example 7:

[0110] Different from Example 5, the thickness of Powder Tablet 1 is 1.00 mm, and the tap density of Powder Tablet 1 is 2.20 g / cm 3 , and the infiltration time of Powder Tablet 1 is 20 s.

[0111] Example 8:

[0112] Different from Example 5, the thickness of Powder Tablet 1 is 2.80 mm, and the tap density of Powder Tablet 1 is 1.10 g / cm 3 , and the infiltration time of Powder Tablet 1 is 30 s.

[0113] The infiltration rates of the electrolytes in Examples 1 to 8 and the liquid absorption amounts of Powder Tablet 1 are calculated. The calculation results are shown in Table 1.

[0114] Table 1 Comparison of Infiltration Performance of Electrode Materials

[0115]

[0116] First of all, as can be seen from Table 1, in Examples 1 to 4, graphite shows a relatively fast infiltration rate and a high liquid absorption amount in all examples. Especially in Example 4, its porosity is as high as 45.20%, the infiltration rate is 0.25 mm / s, and the liquid absorption amount reaches 1.00 g, which indicates that graphite has good electrolyte infiltration performance. In addition, the infiltration time of graphite is also relatively short, indicating that the electrolyte can quickly penetrate into the interior of the graphite electrode material.

[0117] In Examples 5 to 8, the infiltration performance of lithium iron phosphate is weaker than that of graphite. Its infiltration rate is generally low, and the liquid absorption amount is also relatively small. Although the porosity of Example 5 is as high as 43.71%, its infiltration rate is only 0.04 mm / s, and the liquid absorption amount is only 0.46 g. This indicates that the electrolyte infiltration performance of the lithium iron phosphate material is relatively weak.

[0118] Therefore, the graphite electrode material is superior to the lithium iron phosphate electrode material in terms of wetting performance. Graphite has a faster wetting rate, a higher liquid absorption capacity, and a shorter wetting time, which is beneficial to improving the performance of the battery.

[0119] Secondly, in Examples 1 to 8, the wetting process of the electrolyte from the upper surface to the lower surface of the powder tablet 1 was recorded by a camera, and the wetting rate of the electrolyte was calculated based on the thickness of the powder tablet 1 and the wetting time. Compared with the existing contact angle measurement method, wetting height method, and wetting mass measurement method (also known as the wetting balance method), the detection method in Examples 1 to 8 provides an intuitive observation of the wetting behavior. This not only helps researchers understand the wetting mechanism of the electrolyte but also ensures the accurate measurement of the wetting time. Calculating the wetting rate using the thickness of the powder tablet 1 and the wetting time further improves the accuracy of the test and provides reliable data for the quantitative evaluation of the battery performance.

[0120] Meanwhile, the test steps are relatively simple, without the need for complex equipment or cumbersome pretreatment processes. Moreover, the influence of other conductive agents, binders, and dispersants is excluded, and only the ease of wetting of the electrode material by the electrolyte is studied, thus simplifying the problem and improving the accuracy of the analysis.

[0121] In addition, the detection method for the wetting property of the electrolyte in the embodiments of the present invention is not only applicable to graphite and lithium iron phosphate but can also be applied to other types of negative electrode material powders or positive electrode material powders as long as these materials can be made into powder tablets 1 and meet the test requirements.

[0122] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to encompass all changes falling within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A method for detecting the wettability of an electrolyte, characterized in that, The detection method includes: Preparing a powder tablet (1) containing an electrode material; Pasting an adhesive tape (2) on one side of the powder tablet (1) to obtain a sample; Placing the sample on a transparent plate (3), with the side of the powder tablet (1) facing away from the adhesive tape (2) abutting against the transparent plate (3); Dropping an electrolyte on the upper surface of the powder tablet (1), and recording the infiltration time taken for the electrolyte to reach the lower surface of the powder tablet (1) from the upper surface thereof and the color change of the lower surface of the powder tablet (1) during the infiltration process; Calculating the infiltration rate of the electrolyte by using the thickness of the powder tablet (1) and the infiltration time.

2. The method for detecting the wettability of the electrolyte according to claim 1, characterized in that, The preparation method of the tablet includes: Mixing and stirring an electrode material powder, a binder, and a solvent to form a slurry; Coating the slurry on the surface of a foil, and drying the slurry; After drying is completed, peeling the slurry from the foil, and grinding and sieving the slurry to obtain a tablet material with uniform particles; Performing a pressing treatment on the weighed tablet material to obtain the powder tablet (1).

3. The method for detecting the wettability of the electrolyte according to claim 2, characterized in that: Placing the slurry coated on the surface of the foil in a blast drying oven for drying, wherein the drying temperature is 95°C to 115°C, and the drying time is 20 to 30 min.

4. The method for detecting the wettability of the electrolyte according to claim 2, wherein: The sieving mesh number of the ground slurry is 80 to 120 meshes.

5. The method for detecting the wettability of the electrolyte according to claim 2, characterized in that: Before drying the slurry, the mass ratio of the electrode material powder, the binder, and the solvent is 7:(0.2 to 0.4):(9.6 to 9.8).

6. The method for detecting the wettability of the electrolyte according to claim 1, characterized in that: The center of the adhesive tape (2) has a through hole (21), and the electrolyte is dropped on the upper surface of the powder tablet (1) through the through hole (21), and the center of the through hole (21) and the center of the powder tablet (1) are on the same axis.

7. The method for detecting the wettability of the electrolyte according to claim 1, wherein: The area S1 of the through hole (21) and the area S2 of the upper surface of the powder compact (1) satisfy the relational expression:

8. The method for detecting the wettability of the electrolyte according to claim 1, characterized in that, The detection method further includes: Immersing the infiltrated sample in a beaker filled with an electrolyte for 1 to 3 min; After the immersion ends, removing the electrolyte not absorbed by the sample on the surface of the sample, weighing, and calculating the liquid absorption amount of the sample; Wherein, the liquid absorption amount L of the powder tablet (1) satisfies the relational expression: L = G3 - (G1 + G2), G1 is the weight of the powder tablet (1) before infiltration, G2 is the weight of the adhesive tape (2), and G3 is the weight of the sample after immersion.

9. The method for detecting the wettability of the electrolyte according to claim 2, characterized in that: A camera is installed at the bottom of the transparent plate (3), and the infiltration time taken for the electrolyte to reach the lower surface of the powder tablet (1) from the upper surface thereof is recorded through the camera.

10. Use of a method for detecting wettability of an electrolyte according to any one of claims 1 to 9, characterized in that: The detection method is applied to the field of lithium-ion batteries.

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