Method for manufacturing porous particles, method for manufacturing electrodes using porous particles, method for manufacturing secondary batteries
The method accurately estimates the specific surface area of porous particles through weight and particle size sorting, ensuring uniformity and enhancing battery performance by using these particles in lithium-ion secondary batteries.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOYOTA BATTERY CO LTD
- Filing Date
- 2024-12-25
- Publication Date
- 2026-07-07
Smart Images
Figure 2026113265000001_ABST
Abstract
Description
[Technical Field]
[0001] This invention relates to a method for manufacturing porous particles, a method for manufacturing electrodes using porous particles, and a method for manufacturing a secondary battery, and more particularly to a method for manufacturing porous particles that allows for proper selection of porous particles using a simple method, a method for manufacturing electrodes using porous particles, and a method for manufacturing a secondary battery. [Background technology]
[0002] Porous particles can have functions for specific purposes. For example, in positive electrode active materials, multiple primary particles of lithium transition metal oxide can be aggregated to produce secondary particles with many voids, a large specific surface area, and low reaction resistance. Also, for example, porous particles of trilithium phosphate may be added to the positive electrode composite layer of the positive electrode plate of a lithium-ion secondary battery. Adding such porous particles can suppress metal elution from the positive electrode active material, suppress the decomposition of the non-aqueous electrolyte, and suppress the action of hydrofluoric acid. In the case of such porous particles, the reactivity and other functions they exhibit depend on their surface area, so the specific surface area [m²] is important. 2 The [g] is important.
[0003] Therefore, in the invention of trilithium phosphate described in Patent Document 1, for example, the dried material is crushed and sorted to obtain a predetermined specific surface area [m²]. 2 A method for producing trilithium phosphate for non-aqueous secondary batteries is disclosed, which includes a classification step to obtain trilithium phosphate in powder form at a concentration of [ / g].
[0004] In this invention, it is assumed that small trilithium phosphate particles have a large specific surface area, and large trilithium phosphate particles have a small specific surface area. And the specific surface area [m 2 In order to obtain trilithium phosphate particles with a specific surface area [m² / g] greater than a predetermined value, larger trilithium phosphate particles are selectively removed, for example, by a rotary dry sieve. In such a classification process, the specific surface area [m² / g] 2 The goal is to obtain trilithium phosphate particles with a value greater than the set value [ / g].
[0005] With such a method, porous particles with a specific surface area [m 2 / g] larger than the set value can be selectively obtained.
Prior Art Documents
Patent Documents
[0006]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0007] However, assuming that lithium phosphate particles with a small particle size have a large specific surface area [m 2 / g] and lithium phosphate particles with a large particle size have a small specific surface area [m 2 / g], estimating the specific surface area [m 2 / g] is premised on the particles being solid porous particles without voids inside. For example, in some cases, small primary particles are aggregated to increase the specific surface area [m 2 / g] to form secondary particles with gaps inside. In the case of such porous particles, even if the specific surface area [m 2 / g] is estimated based only on the particle diameter, it will be inaccurate due to the degree of internal gaps.
[0008] On the other hand, although it is possible to measure the specific surface area [m 2 / g] by the BET method or the like in an actual production line, in reality, it is extremely complicated and significantly reduces production efficiency. The problems to be solved by the method for producing porous particles, the method for producing an electrode using the porous particles, and the method for producing a secondary battery of the present invention are to accurately estimate the specific surface area of the porous particles by a simple method.
Means for Solving the Problems
[0009] To solve the above problems, the present invention provides a method for producing porous particles, comprising: a weight sorting step of sorting porous particles to be used as raw materials so that the weight per unit amount falls within a set range; a particle size sorting step of sorting the porous particles sorted by the weight sorting step so that they fall within a set particle size range; and a step of determining the particle size of the porous particles that gives a target specific surface area of the porous particles with respect to the weight per unit amount of the porous particles sorted by the weight sorting step and storing the correspondence relationship, wherein the particle size sorting step is characterized by setting a threshold for the particle size based on the correspondence relationship with respect to the weight per unit amount of the porous particles after the weight sorting step and sorting.
[0010] Furthermore, the method includes a particle size sorting step for sorting porous particles to be used as raw materials so that they fall within a set particle size range, a weight sorting step for sorting the porous particles sorted in the particle size sorting step so that their weight per unit amount falls within a set range, and a step for determining the weight per unit amount of the porous particles that gives a target specific surface area of the porous particles with respect to the particle size of the porous particles sorted in the particle size sorting step and storing the correspondence relationship, wherein the weight sorting step is characterized by setting a threshold for the weight per unit amount of the porous particles based on the correspondence relationship with respect to the particle size of the porous particles after the particle size sorting step and sorting them.
[0011] The weight sorting process allows the porous particles, which are to be used as raw materials, to be sorted by a cyclone-type classifier so that their weight per unit amount reaches a set threshold. The particle size sorting step allows the porous particles, which are to be used as raw materials, to be sorted by a screen-type classifier having a screen with a mesh size that corresponds to a set threshold particle size.
[0012] Furthermore, in order to solve the above problems, the method for manufacturing an electrode using porous particles of the present invention involves incorporating the porous particles manufactured by the above-described method for manufacturing porous particles into the composite layer of the electrode. This method can be suitably implemented when the porous particles are a positive electrode active material. This method can also be suitably implemented when the porous particles are trilithium phosphate.
[0013] Furthermore, in order to solve the above problems, the method for manufacturing a secondary battery of the present invention uses electrodes manufactured by the above-described electrode manufacturing method. In addition, these electrodes can be suitably implemented in a lithium-ion secondary battery. [Effects of the Invention]
[0014] According to the method for producing porous particles, the method for producing electrodes using porous particles, and the method for producing secondary batteries of the present invention, the specific surface area of porous particles can be accurately estimated by a simple method. [Brief explanation of the drawing]
[0015] [Figure 1] This is a schematic diagram illustrating porous particles. [Figure 2] This flowchart shows the procedure for manufacturing a positive electrode plate according to the first embodiment. [Figure 3] This flowchart shows the procedure for manufacturing a positive electrode plate according to the second embodiment. [Figure 4] This graph shows the relationship between the particle size [μm] and specific surface area [m² / m³] of porous particles. [Figure 5] This graph shows the relationship between the porosity [%] inside porous particles and the specific surface area [m² / m³]. [Figure 6] This table shows the relationship between differences in the manufacturing procedure of positive electrode plates and the standard deviation of the specific surface area [m2 / m3] after the sorting process. [Figure 7] This is a perspective view showing a schematic representation of the external configuration of the lithium-ion secondary battery of this embodiment. [Figure 8] This is a schematic diagram showing a partially unfolded configuration of the wound electrode body. [Figure 9] This flowchart shows an example of a manufacturing method for the lithium-ion secondary battery of this embodiment. [Modes for carrying out the invention]
[0016] The methods for manufacturing porous particles, manufacturing electrodes using porous particles, and manufacturing secondary batteries of the present invention will be described below with reference to Figures 1 to 9, based on embodiments. In this embodiment, the positive electrode plate 3 of the lithium-ion secondary battery 1 will be described as a method for manufacturing a positive electrode plate 3 in which a positive electrode active material consisting of secondary particles formed by aggregating multiple primary particles of lithium transition metal oxide as porous particles 5 is used in the positive electrode composite layer 32. However, the present invention is not intended to be understood as being limited to this embodiment.
[0017] (Summary of this embodiment) In this embodiment, porous particles 5, which are positive electrode active materials made of secondary particles, are used in the positive electrode composite layer 32 of the positive electrode plate 3 of the lithium-ion secondary battery 1. Here, some battery performance depends on the specific surface area of the positive electrode active material, but in the case of porous particles, even particles of the same size can have large differences in specific surface area due to the proportion of voids, etc. Therefore, the specific surface area of the porous particles 5, which are the positive electrode active materials made of secondary particles that serve as raw materials, [m²] 2 The [g] is important.
[0018] Figure 1 is a schematic diagram showing the positive electrode active material, which is the porous particle 5 of this embodiment. When the porous particle 5 has a particle size D [μm], it is composed of solid particle portions 5a and hollow portions 5b between the solid particle 5a. However, there is variation in the volume ratio between the solid particle portions 5a and the hollow portions 5b. Therefore, porous particles 5 with the same particle size D [μm] and the density [g / m³] of the positive electrode active material itself are considered. 3 Even if ] is known, the particle weight W [g] and porosity P [%] of the porous particle 5 are not constant and vary. Thus, even with the same particle size D [μm], the interior contains solid particles 5a and hollow voids 5b, and even with the same particle size D, the specific surface area [m 2 / g] is different.
[0019] Therefore, as shown in Figure 4, the specific surface area [m²] is not determined by the particle size D [μm] alone. 2 It is not possible to accurately estimate [ / g]. Note that this "specific surface area" is the surface area for a given weight [m²]. 2 While it is often expressed as [m² / g], in this embodiment, the "specific surface area S" is expressed as the surface area per unit volume [m²]. 2 / m 3 Represented by ].
[0020] Therefore, this embodiment includes a "weight sorting step (Figures 2 and 3: S11)" for sorting the porous particles 5, which are the raw materials, so that their particle weight W [g] falls within a set range. It also includes a "particle size sorting step (Figures 2 and 3: S12)" for sorting the particles so that their particle size D [μm] falls within a set range. The order of these steps is determined by their purpose and effect.
[0021] From this sorting process using "weight sorting (Figures 2 and 3: S11)" and "particle size sorting (Figures 2 and 3: S12)", the specific surface area S[m²] can be correctly determined. 2 / m 3 We estimate the uniform specific surface area S[m²]. 2 / m 3 By using the porous particles 5, the functionality of the positive electrode active material consisting of the porous particles 5 can be effectively exercised.
[0022] Therefore, the present invention will be described with reference to two embodiments with reference to Figures 2 and 3. <Particle weight W [g], particle diameter D [μm], specific surface area S [m] 2 / m 3 ]> In this embodiment, the specific surface area S[m²] 2 / m 3 To suppress variations in ], the particle weight W [g], particle size D [μm], and specific surface area S [m²] are used. 2 / m 3 ] is used. First, as a premise of this embodiment, the particle weight W [g], particle size D [μm], and specific surface area S [m 2 / m 3 ] explains.
[0023] In this application, "weight per unit quantity" refers to the weight per unit volume, such as density [g / m³]. 3 In addition, in the weight sorting process (S11) of this embodiment, it may also refer to the weight [g] of each individual porous particle 5. In this embodiment, the average weight [g] of each individual porous particle 5 is referred to as "particle weight W [g]".
[0024] To calculate the particle size D [μm], a portion of the positive electrode composite layer 32 is cut out, and a three-dimensional model is generated using FIB-SEM (Focused Ion Beam Scanning Electron Microscopes) and X-ray CT (Computed Tomography). Here, the particle size D [μm] is essentially the projected one-dimensional length. FIB-SEM is a combined device that combines a focused ion beam (FIB) device and a scanning electron microscope (SEM). Using these three-dimensional models created with FIB-SEM and X-ray CT, the particle characteristic distribution results are used to determine the particle sorting threshold and confirm the standard deviation. For analysis such as threshold determination, it is also possible to perform analysis using devices such as BET (Berunauer Emmett and Teller's method - gas adsorption method), LD (laser analysis method), DIA (dynamic image analysis method), and DSL (dynamic light scattering method) particle size distribution analyzers.
[0025] The specific procedure for analyzing the 3D model in this embodiment is described below. After kneading, coating, and drying processes using porous particles 5 according to each condition, a positive electrode plate 3 is created before the pressing process. With the created positive electrode plate 3 embedded in resin, continuous cross-sectional images are taken using a FIB-SEM. Then, a region of approximately 25 [μm] square within the positive electrode plate 3 is visualized as a 3D model. From this 3D model, each individual particle is extracted and its particle size D [μm], particle weight W [g], and specific surface area S [m²] are determined. 2 / m 3 ] is also calculated.
[0026] In this embodiment, the particle size D[μm] is determined by a sieve standard in which the particle size D[μm] in the particle size sorting step (S12) is defined as the diameter of the porous particles 5 that pass through a sieve with the same mesh size as the threshold for the porous particles 5 to be sorted.
[0027] Furthermore, in the case of "particle size D" in this embodiment, unless otherwise specified, the measurement of porous particles 5 directly refers to the median diameter (d50) in the frequency distribution measured by laser diffraction. Similarly, unless otherwise specified, other median values also refer to the median value.
[0028] In this embodiment, "classification" refers not only to particle size D [μm], but also to particle weight W [g] and density [g / cm³]. 3 A collection of non-uniform porous particles 5, such as ], with a particle size D [μm], particle weight W [g], and density [g / cm³]. 3 This involves sorting based on criteria such as [ ].
[0029] <Particle size D [μm] and specific surface area S [m²] 2 / m 3 ] Relationship > Figure 4 shows the particle size D [μm] and specific surface area S [m²] of the porous particle 5. 2 / m 3 This graph shows the relationship between [ ]. The horizontal axis represents the index obtained by dividing the particle size D [μm] of each porous particle 5 by the median value (d50) of particle size D [μm]. The vertical axis represents the specific surface area S [m 2 / m 3 This shows that, as is clear from Figure 4, for porous particles 5, for the reasons mentioned above, the particle size D [μm] and the specific surface area S [m 2 / m 3 It can be seen that there is no correlation with ]. Therefore, from particle size D [μm] to specific surface area S [m 2 / m 3 ], or specific surface area S[m 2 / m 3 Figure 4 confirms that it is difficult to estimate the particle size D [μm] from [ ].
[0030] <Void ratio P[%] and specific surface area S[m2 / m 3 ] Relationship > Figure 5 shows the porosity P[%] and specific surface area S[m²] inside the porous particle 5. 2 / m 3 This graph shows the relationship between [ ]. The horizontal axis represents the porosity P [%] inside the porous particle 5. The vertical axis represents the specific surface area S [m 2 / m 3 This graph shows the porosity P[%] and specific surface area S[m²] inside the porous particle 5. 2 / m 3 This indicates a strong correlation. In other words, porous particles 5 with a high porosity P[%] have many hidden "surfaces" inside, so a high porosity P[%] results in a high specific surface area S[m 2 / m 3 ] becomes higher. In other words, if the porosity P[%] inside the porous particle 5 is known, the specific surface area S[m 2 / m 3 ] can be estimated. Conversely, the specific surface area S[m 2 / m 3 If [ ] is known, the porosity P [%] inside the porous particle 5 can be estimated.
[0031] Generally, the specific surface area S[m²] 2 / m 3 Therefore, measuring the porosity P[%] inside porous particles 5 is relatively easy. For example, in the liquid immersion method, the porous sample is immersed in a liquid with good wettability, and the voids are saturated with the liquid. In the water saturation method, the (opening) void volume can be determined by subtracting the volume of water remaining after immersion from the initial volume. In the mercury intrusion method, external pressure must be applied to allow mercury, which has high surface tension, to penetrate into the fine pores. In this case, the distribution of pore diameters and pore volume can also be determined by measuring the amount of intrusion relative to the magnitude of the pressure. However, in any case, the process is extremely complicated.
[0032] Therefore, in this embodiment, the specific surface area S[m²] is controlled by the particle weight W[g] of the porous particle 5, which is a parameter that depends on the porosity P[%]. 2 / m 3 We decided to obtain []. <Relationship between porosity P[%] and particle weight W[g]> Here, one way to calculate the porosity P[%] is by measuring it using the immersion method described above. However, measuring it using the immersion method in the manufacturing process is extremely complicated and significantly reduces productivity. Therefore, in this embodiment, the porosity P[%] is derived from the particle weight W[g]. First, the volume V[μm] is calculated from the particle size D1[μm] of the porous particle 5. 2 Calculate the volume V[μm]. 2 ] and the density of the positive electrode active material De[g / cm³ 3 Multiplying by ] allows us to calculate the particle weight W0 [g] of a porous particle 5 with a particle size D1 [μm] if it is solid with no voids 5b. Let the actual weight of a porous particle 5 with voids 5b be the particle weight W1 [g]. Then the porosity P [%] can be calculated by "P = W1 / W0". In other words, the porosity P [%] can be considered as a function of the particle size D1 [μm] of the porous particle 5 and the weight of the porous particle 5, which is the particle weight W1 [g]. Therefore, by specifying the particle size D1 [μm] of the porous particle 5 and the weight of the porous particle 5, which is the particle weight W1 [g], we can obtain a porous particle 5 with a predetermined porosity P [%].
[0033] Then, from the porosity P[%], the specific surface area S[m 2 / m 3 It is possible to estimate ]. In other words, if you know the particle weight W [g] and particle size D [μm], you can find the porosity P [%], and if you know the porosity P [%], you can find the specific surface area S [m²]. 2 / m 3 ] can be understood.
[0034] <Principle of this embodiment> In this embodiment, based on the above relationship, a sorting process is provided that includes particle size D1 [μm] and particle weight W1 [g] in order to obtain porous particles 5 with the required porosity P [%]. The "weight sorting process (Figures 2 and 3: S11)" and the "particle size sorting process (Figures 2 and 3: S12)" are collectively referred to as the "sorting process".
[0035] The sorting process includes a "weight sorting process (Figures 2 and 3: S11)" in which the particle weight W [g] of the porous particles 5, which are the cathode active material and are the raw material, is sorted so that it falls within a set range. Along with this, there is also a "particle size sorting process (Figures 2 and 3: S12)" in which the particles are sorted so that they fall within a set particle size D [μm] range. As a result, the porosity P [%] of the sorted porous particles 5 becomes uniform. Furthermore, the relationship between porosity P [%] and specific surface area S [m²] is also determined. 2 / m 3 There is a strong correlation with ], therefore the specific surface area S[m²] of the porous particles 5 after sorting. 2 / m 3 ] can also be made homogeneous.
[0036] Therefore, the specific surface area S[m²] of the target porous particles 5 is determined based on the particle weight W[g] of the porous particles 5 selected in this weight sorting process (S11). 2 / m 3 The process includes a step of determining the particle size D [μm] of the porous particles 5 such that ] and storing the corresponding relationship. Then, the particle size sorting step (S12) sorts the porous particles 5 after the weight sorting step (S11) by setting a threshold for particle size D [μm] based on the corresponding relationship.
[0037] The homogeneous specific surface area S[m²] selected in this manner 2 / m 3 By using porous particles 5 of the positive electrode active material as a raw material, a positive electrode plate 3 can be manufactured with uniform battery performance due to its specific surface area. Furthermore, a lithium-ion secondary battery 1 can be manufactured using such a positive electrode plate 3.
[0038] <First Embodiment> Figure 2 is a flowchart showing the procedure for manufacturing the positive electrode plate 3 according to the first embodiment. First, porous particles 5 of the positive electrode active material, which will be the raw material, along with a conductive additive and a binder, are prepared. It should be noted that, as a prerequisite for carrying out this embodiment, the manufacturing equipment, including well-known sorting devices (not shown), kneaders, coating machines, presses, conveying devices, etc., as well as a control device with various sensors and a computer to control them, is provided.
[0039] First, the porous particles 5 are sorted in a weight sorting process (S11) according to a threshold based on a pre-set particle weight W [g] of the porous particles 5. Then, the specific surface area S [m²] of the target porous particles 5 is determined. 2 / m 3 The system includes a step to determine the threshold particle size D [μm] of the porous particles 5 in the particle size sorting step (S12) so that the result is as follows, and to store the corresponding relationship.
[0040] <Weight sorting process for particles within a specific particle weight range W[g] (S11)> The porous particles 5 undergo a weight sorting process (S11) to separate them into porous particles 5 within a specific particle weight range W[g]. This procedure corresponds to the weight sorting process of the present invention.
[0041] In this embodiment, the porous particles 5 used as raw material are a mixture of porous particles 5 with various particle weights W [g]. Therefore, the target specific surface area S [m 2 / m 3 To achieve this, first, porous particles 5 with a specific particle weight W [g] are classified and selected.
[0042] In this embodiment, a cyclone-type classifier (not shown) is used as an example. An example of a cyclone-type classifier is, for example, "Powder Systems Co., Ltd.'s Cyclone." The cyclone-type classifier may be either a dry type, where the porous particles 5 are left dry, or a wet type, where a solvent is added. The cyclone-type classifier performs classification by pouring a gas or liquid at high speed into a conical container and pushing the powdery solid outwards (towards the inner wall of the container) by centrifugal force. In this embodiment, classification is performed based on particle weight W [g]. In the cyclone-type classifier, porous particles 5 with a relatively large particle weight W [g] that are separated by centrifugal force fall along the side wall of the cyclone, and porous particles 5 with a relatively small particle weight W [g] are discharged from the top. This sorting process allows for the selective sorting of a predetermined weight [g] by sequentially changing the conditions of the raw material. It is also preferable to repeat the process many times to improve the sorting accuracy. In this embodiment, the upper limit of weight [g] is set using a dry cyclone-type classifier, and this process is repeated twice.
[0043] Furthermore, powder classification can be carried out not only by cyclone-type classifiers, but also by centrifugal classifiers, gravity classifiers, inertial classifiers, and other types of classifiers. <Particle size sorting process (S12) for porous particles 5 within a specific particle size range D [μm]> The particle size sorting step (S12) sorts the porous particles 5 after the weight sorting step (S11) by setting a threshold particle size D [μm] based on the correspondence with the particle weight W [g]. As described above, the target specific surface area S [m²] of the porous particles 5 is set. 2 / m 3 There are two conditions for achieving this: it is necessary to have not only a specific particle weight W [g] but also a specific particle size D [μm]. Therefore, after porous particles 5 within a certain range of particle weight W [g] are selected by a weight sorting process (S11) of porous particles 5 within a specific range of particle weight W [g], a particle size sorting process (S12) is performed for particles within a specific particle size D [μm] range.
[0044] Here, the raw material is a mixture of porous particles 5 with various particle sizes D [μm]. Therefore, the target specific surface area S [m²]2 / m 3 To achieve this, porous particles 5 with a specific particle size D [μm] are classified and selected based on a threshold.
[0045] In this embodiment, a screen-type classifier (not shown) is used as an example. An example of a screen-type classifier is the "Turbo Screener manufactured by Freund Turbo Co., Ltd." In this embodiment, classification is performed using a classifier equipped with a screen (sieve) with a mesh size of particle size D [μm] as an example. The screen separates the porous particles 5 into particles larger than the mesh opening and particles smaller than the mesh opening. For example, a cylindrical screen is rolled or vibrated to continuously and efficiently sieve the particles. This can be done in a dry manner with the particles in their dry state, or in a wet manner with a solvent added. This sieving may be divided into multiple stages and classified sequentially. It is also preferable to perform repeated sorting to obtain porous particles with higher accuracy in particle size D [μm]. In this embodiment, sorting is performed in two steps.
[0046] Specifically, in the first step, a screen with the maximum mesh size within the desired particle size D [μm] range is used to remove porous particles 5 that exceed the maximum particle size D [μm]. In the second step, a screen with the minimum mesh size within the desired particle size D [μm] range is used to remove porous particles 5 that do not exceed the minimum particle size D [μm]. In this way, the particle size D [μm] of the porous particles 5 can be made to fall within the range of the maximum and minimum values. It is also preferable to use a multi-step procedure to achieve a particle size D [μm] with even less variation.
[0047] It goes without saying that particle size D [μm] classification is not limited to screen-type classifiers and can be performed with other classification devices as well. <Mixing (S13)> Next, the porous particles 5 of the positive electrode active material, the conductive additive, and the binder are mixed together with a solvent in a kneader (not shown) (S13). As described above, the porous particles 5 sorted to a specific particle weight W [g] and a specific particle size D [μm] by a weight sorting step (S11) of porous particles 5 within a specific particle weight range W [g] and a particle size sorting step (S12) of porous particles 5 within a specific particle size range D [μm] are mixed together.
[0048] Mixing is carried out using a well-known mixer (e.g., twin-shaft mixer, planetary mixer, disper) with predetermined temperature [°C], rotation speed [rpm], time [sec], torque [N], etc. Once mixing (S13) is complete, a positive electrode mixture paste is produced.
[0049] <Coating (S14)> The coating (S14) can be carried out by a well-known procedure. For example, a long positive electrode current collector foil 31 is conveyed at a constant speed in the longitudinal direction. While conveying, the positive electrode composite paste produced in the kneading (S13) procedure is discharged from a well-known coating machine (not shown) equipped with a die nozzle at a predetermined opening and predetermined discharge pressure, and a predetermined amount is coated onto predetermined positions on the positive electrode current collector foil 31.
[0050] <Drying (S15)> In the coating (S14) procedure, the positive electrode composite paste coated onto the positive electrode current collector foil 31 is dried with hot air at a predetermined temperature and airflow. This drying causes the solvent in the positive electrode composite paste to evaporate. Once the solvent in the positive electrode composite paste has evaporated, the paste solidifies, forming the positive electrode composite layer 32.
[0051] <Press (S16)> In the pressing (S16) step, the positive electrode composite layer 32 formed in the drying (S14) step is pressed to a predetermined thickness using, for example, a well-known roll press (not shown), and its surface is processed to be smooth.
[0052] This completes the manufacturing process for the positive electrode plate 3. <Second Embodiment> The second embodiment is different from the first embodiment only in that the order of implementation of the particle weight selection step (S11) for particles in a specific particle weight range W [g] and the particle size selection step (S12) for particles in a specific particle size range D [μm] is different. Since the detailed description of each procedure is the same as that of the first embodiment, the description thereof is omitted.
[0053] Also, the procedure is different in the following points. First, the threshold values in the particle size selection step (S12) and the weight selection step (S11) are set and stored in advance from the above-described relationship so that the target specific surface area S [m 2 / m 3 is obtained. Then, based on this threshold value, the porous particles are selected in the particle size selection step (S12). Subsequently, in the weight selection step (S11), the porous particles 5 with the selected particle size D [μm] are selected with the set threshold value of the particle weight W [g].
[0054] Note that the configuration of the second embodiment is different from that of the first embodiment in that the order of implementation of the weight selection step (S11) for the porous particles 5 in a specific particle weight range W [g] and the particle size selection step (S12) for the porous particles 5 in a specific particle size range D [μm] is different.
[0055] Since the order is different, a step of obtaining the particle weight W [g] of the porous particles 5 such that the target specific surface area S [m 2 / m 3 of the porous particles 5 is obtained with respect to the particle size D [μm] of the porous particles 5 and storing the correspondence relationship is provided.
[0056] In the particle size selection step (S12), the threshold value of the particle weight W [g] of the porous particles 5 is set and selected based on the correspondence relationship with respect to the particle size D [μm] of the porous particles 5 after the weight selection step (S11).
[0057] Also, since the order is different, the effects are also different. This point will be described in detail in the experimental examples. <Configuration of the lithium ion secondary battery 1> Figure 7 is a perspective view showing a schematic of the external configuration of the lithium-ion secondary battery 1 of this embodiment. First, the configuration of the lithium-ion secondary battery 1 of this embodiment will be described.
[0058] As shown in Figure 7, the lithium-ion secondary battery 1 is configured as a cell battery. The lithium-ion secondary battery 1 includes a plate-shaped rectangular parallelepiped battery case 11 with an opening on the top. An electrode body 12 is housed inside the battery case 11. The battery case 11 is filled with a non-aqueous electrolyte 13 through an injection hole. The battery case 11 is made of a metal such as an aluminum alloy and forms a sealed battery case with a lid. The lithium-ion secondary battery 1 also includes a positive electrode external terminal 14 and a negative electrode external terminal 15 used for charging and discharging power. The positive electrode external terminal 14 is electrically connected to a positive electrode current collector terminal 16 inside the battery case 11 via the lid. The negative electrode external terminal 15 is electrically connected to a negative electrode current collector terminal 17 inside the battery case 11 via the lid. The positive electrode current collector terminal 16 is electrically connected to the positive electrode current collector portion 33 (see Figure 8) of the electrode body 12. Furthermore, the negative electrode current collector terminal 17 is electrically connected to the negative electrode current collector section 23 (see Figure 8) of the electrode body 12.
[0059] <Electrode body 12> Figure 8 is a schematic diagram showing a partially unfolded configuration of the wound electrode body 12. The electrode body 12 is made up of a number of stacked negative electrode plates 2, positive electrode plates 3, and separators 4 placed between them. The stacked negative electrode plates 2, positive electrode plates 3, and separators 4 are wound together to form a flat shape. The negative electrode plate 2 has a negative electrode composite layer 22 formed on a negative electrode current collector foil 21 made of copper foil, which serves as the base material. A negative electrode current collector 23 is provided on one end in the width direction (winding axis direction) perpendicular to the winding direction (winding direction L).
[0060] This negative electrode current collector section 23 is the part of the negative electrode current collector foil 21 in which the negative electrode composite layer 22 is not formed and the copper foil of the negative electrode current collector foil 21 is exposed, corresponding to the "uncoated region" of the present invention. The positive electrode plate 3 has a positive electrode composite layer 32 formed on a positive electrode current collector foil 31 made of aluminum foil, which serves as the base material. As shown in Figure 8, the positive electrode current collector portion 33 is provided on the other end (opposite side from the negative electrode current collector portion 23) in the width direction (winding axis direction) perpendicular to the winding direction (winding direction L) of the positive electrode current collector foil 31. The positive electrode composite layer 32 is not formed on the positive electrode current collector portion 33, and the metal of the positive electrode current collector foil 31 is exposed.
[0061] <Laminated structure of electrode body 12> As shown in Figure 8, the basic configuration of the electrode body 12 of the lithium-ion secondary battery 1 includes a negative electrode plate 2, a positive electrode plate 3, and a separator 4.
[0062] The negative electrode plate 2 has a negative electrode composite material layer 22 on both sides of the negative electrode current collector foil 21, which serves as the negative electrode base material. One end of the negative electrode current collector foil 21 is a negative electrode current collector portion 23 where metal is exposed. The positive electrode plate 3 has a positive electrode composite material layer 32 on both sides of the positive electrode current collector foil 31, which serves as the positive electrode base material. The other end of the positive electrode current collector foil 31 is a positive electrode current collector portion 33 where metal is exposed.
[0063] The negative electrode plate 2 and the positive electrode plate 3 are stacked on top of each other via a separator 4 to form a laminate. As shown in Figure 8, this laminate is wound longitudinally around a winding axis and shaped into a flattened form as shown in Figure 7 to form a wound-type electrode body 12.
[0064] <Nonaqueous electrolyte 13> In the lithium-ion secondary battery 1 of this embodiment shown in Figure 7, the non-aqueous electrolyte 13 is held by a separator 4. The non-aqueous electrolyte 13 is a composition obtained by dissolving a lithium salt in an organic solvent. Examples of lithium salts that can be used include LiClO4, LiPF6, LiAsF6, LiBF4, LiSO3CF3, etc. Examples of organic solvents include cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and trifluoropropylene carbonate; linear carbonates such as diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, and dipropyl carbonate; ether compounds such as tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane; sulfur compounds such as ethylmethylsulfone and butanesultone; or phosphorus compounds such as triethyl phosphate and trioctyl phosphate. One or more of these can be mixed and used as the non-aqueous electrolyte 13. However, the composition of the non-aqueous electrolyte 13 is not limited to these.
[0065] <Components of electrode body 12> Next, we will describe the components that make up the electrode body 12: the negative electrode plate 2, the positive electrode plate 3, and the separator 4.
[0066] <Negative electrode plate 2> As shown in Figure 8, the negative electrode plate 2 is constructed by forming a negative electrode composite material layer 22 on both sides of the negative electrode current collector foil 21, which is the negative electrode substrate. The negative electrode composite material layer 22 is formed in the source process (Figure 9: S1) by coating the negative electrode current collector foil 21 with negative electrode composite material paste. The negative electrode plate 2 is then completed through a drying process, a pressing process, and a cutting process.
[0067] <Negative electrode current collector foil 21> The negative electrode current collector foil 21 is a metal foil made of Cu or a Cu alloy, and in this embodiment, it is made of Cu foil. The negative electrode current collector foil 21 serves as a base as aggregate for the negative electrode composite layer 22 and also functions as a current collector that collects electricity from the negative electrode composite layer 22. One end of the negative electrode current collector foil 21 is a negative electrode current collector section 23 where the metal surface is exposed and the negative electrode composite layer 22 is not formed thereon. In other words, the negative electrode active material particles are electrically connected to the negative electrode external terminal 15 via the negative electrode current collector foil 21, the negative electrode current collector section 23, and the negative electrode current collector terminal 17.
[0068] <Negative electrode composite layer 22> The negative electrode composite layer 22 consists of a negative electrode active material as the raw material, and a binder (binding agent) and additives as auxiliary materials. The raw material and auxiliary materials are mixed with an organic solvent to produce a negative electrode composite paste. This negative electrode composite paste is coated onto the negative electrode current collector foil 21. The coated negative electrode composite paste is dried and adheres to the negative electrode current collector foil 21 by the binder.
[0069] <Negative electrode active material> In this embodiment, the negative electrode active material is powdered graphite particles made of graphite having a layered structure, and lithium ions Li + It is a material capable of absorbing and releasing substances.
[0070] <Positive plate 3> As shown in Figure 8, the positive electrode plate 3 consists of a positive electrode substrate, which is a positive electrode current collector foil 31, and a positive electrode composite layer 32 coated thereon. The positive electrode composite layer 32 is formed in the source process (Figure 9: S1) when a positive electrode composite paste is applied to the positive electrode current collector foil 31. The positive electrode plate 3 is then completed through a drying process, a pressing process, and a cutting process.
[0071] <Positive current collector foil 31> The positive electrode plate 3 is constructed by forming a positive electrode composite material layer 32 on both sides of a positive electrode current collector foil 31, which is the positive electrode base material. In this embodiment, the positive electrode current collector foil 31 is made of aluminum foil. The positive electrode current collector foil 31 serves as the base material for the positive electrode composite material layer 32 and also functions as a current collector that collects electricity from the positive electrode composite material layer 32.
[0072] First, although Al foil was used as an example for the positive electrode substrate constituting the positive electrode current collector foil 31, it can be made of a conductive material consisting of a metal with good conductivity, for example. As a material with good conductivity, in addition to Al foil, materials containing Al alloys can be used. The composition of the positive electrode current collector foil 31 is not limited to this.
[0073] <Positive electrode composite layer 32> The positive electrode composite layer 32 is formed by coating the positive electrode composite paste onto the positive electrode current collector foil 31 and drying it. The positive electrode composite layer 32 contains positive electrode active material particles as well as additives such as conductive additives, binders, and dispersants.
[0074] In this embodiment, a positive electrode active material consisting of porous particles 5 is used. <Composition of positive electrode active material> The positive electrode active material particles, which are porous particles 5 in this embodiment, are composed of secondary particles formed by the aggregation of a plurality of primary particles, as shown in Figure 1. They have a hollow structure comprising an outer shell formed by the aggregated primary particles and a space inside the outer shell. They consist of solid particle portions 5a and gaps 5b, which are hollow portions between the solid particles 5a. In a secondary battery using such a hollow positive electrode active material, capacity characteristics, cycle characteristics, and output characteristics can be improved compared to a case using a solid positive electrode active material.
[0075] Furthermore, the positive electrode active material particles contain a lithium transition metal oxide having a layered crystalline structure. The lithium transition metal oxide contains one or more predetermined transition metal elements in addition to Li. Preferably, the transition metal elements contained in the lithium transition metal oxide are at least one of Ni, Co, and Mn. The positive electrode active material of this embodiment is a ternary system called NCM, for example LiCo, which has a lithium transition metal oxide containing all of Ni, Co, and Mn. 1 / 3 Ni 1 / 3 Mn 1 / 3 O2 can be used as an example.
[0076] Furthermore, the positive electrode active material in this embodiment is not limited to having a lithium transition metal oxide containing all of Ni, Co, and Mn. It may also contain other compositions, such as Al, or LiFePO4.
[0077] <Separator 4> The separator 4 is a highly insulating nonwoven fabric, such as polypropylene, which is a porous resin, for holding the non-aqueous electrolyte 13 between the negative electrode plate 2 and the positive electrode plate 3. Alternatively, the separator 4 can be a porous polymer membrane such as a porous polyethylene membrane, a porous polyolefin membrane, or a porous polyvinyl chloride membrane, or an ion-conductive polymer electrolyte membrane, either alone or in combination.
[0078] <Manufacturing method for lithium-ion secondary battery 1> Figure 9 is a flowchart showing an example of a manufacturing method for the lithium-ion secondary battery 1 of this embodiment. The manufacturing method for the lithium-ion secondary battery 1 of this embodiment will be described below. The lithium-ion secondary battery 1, which is a cell battery, first has its power generation elements, the negative electrode plate 2, positive electrode plate 3, and separator 4, created in the source process (S1).
[0079] The manufacturing method of the positive electrode plate 3 in this embodiment constitutes a part of this source process (S1). In the source process (S1), the negative electrode plate 2, positive electrode plate 3, and separator 4 are created. Then, in the lamination process (S2), the negative electrode plate 2 and positive electrode plate 3 are stacked and integrated via the separator 4. The laminate thus created is then wound in the winding process (S3) in the winding direction L, as shown in Figure 3. The laminate wound in the winding process (S3) is generally in the shape of a plate. In the wound body pressing process (S4), this wound body is pressed from the thickness direction T by the press surface of an opposing press machine. In the wound body pressing process (S4), the electrode body 12 is pressed until it reaches a specified thickness [mm] so that it fits snugly into the battery case 11 shown in Figure 2.
[0080] In the rewinding press process (S4), when the thickness of the electrode body 12 is adjusted, the assembly process (S5) is performed. This assembly process is the same as the assembly process (S104) of the present embodiment shown in FIG. 5. In the assembly process (S5), as shown in FIG. 2, the negative electrode current collecting terminal 17 and the positive electrode current collecting terminal 16 are attached to the electrode body 12, and further, the negative electrode external terminal 15 and the positive electrode external terminal 14 are attached via the lid body. Then, the electrode body 12 is housed in the battery case 11. Then, the lid body is welded to the battery case 11 to seal the opening. At this stage, since the liquid injection port of the lid body is open, the cell is heated in the cell drying process (S6) to dry the inside of the cell. When the inside of the cell is dried in the cell drying process (S6), in the liquid injection and sealing process (S7), the non-aqueous electrolyte 13 is injected, and the liquid injection port is sealed and hermetically sealed. Thus, the assembly of the lithium ion secondary battery 1 is completed.
[0081] Thereafter, a SEI film is formed by the first charge in the activation process (S8). The first charge in this activation process (S8) is the same process as the first charge in the reduction process (S105) of the present embodiment. Also, in the activation process (S8), in the aging process, it is stored at a high temperature for a long time to eliminate micro short circuits.
[0082] When such an activation process (S8) is completed, in the inspection process (S9), the battery capacity, internal resistance, self-discharge, OCV, etc. are inspected, and those that pass are shipped as products. (Experimental example of the present embodiment) FIG. 6 is a table showing the difference in the procedure of the sorting process of the manufacturing method of the positive electrode plate 3 and the relationship with the standard deviation of the specific surface area S [m 2 / m 3 . Hereinafter, an experimental example of the positive electrode plate 3 manufactured as described above will be described with reference to FIG. 6.
[0083] The "sorting range of particle weight" shown in FIG. 6 is the ratio when the median value of the particle weight W [g] without sorting in Comparative Example 1 corresponding to the prior art is set to "1". That is, the "particle weight" in the "sorting range of particle weight" here is the value obtained by dividing the weight of each porous particle 5 when there is no sorting of the weights of the porous particles 5 in Comparative Example 2 and Examples 1 to 3 by the median value.
[0084] The "particle size sorting range" is the ratio when the median value of the particle size D [μm] without sorting in Comparative Example 1, which corresponds to the conventional technology, is set to "1". In other words, the "particle size" in the "particle size sorting range" referred to here is the value obtained by dividing the particle size D [μm] of each porous particle 5 by the median value when sorting is not performed.
[0085] "Standard deviation of specific surface area after sorting process" refers to the specific surface area S[m²] of Comparative Example 1, which corresponds to the conventional technology, without the sorting process. 2 / m 3 This is the ratio when the standard deviation of ] is set to 100[%]. In other words, the "standard deviation of specific surface area after the sorting process" referred to here is the specific surface area S[m²] of Comparative Example 2 and Examples 1-3. 2 / m 3 This is the value obtained by dividing the standard deviation [%] of [the selected group] by the standard deviation [%] of the group without selection.
[0086] <Experimental conditions> The experiments were conducted using Comparative Examples 1 and 2, and Examples 1 to 3. Prior to the experiment, a preliminary experiment is conducted to confirm the threshold for selection. Additionally, a model is created for two purposes: calculating the standard deviation to confirm whether the variation in specific surface area has been reduced.
[0087] Comparative Example 1 corresponds to the conventional technology in which neither the weight sorting step (S11) for porous particles 5 within a specific particle weight range W [g] nor the particle size sorting step (S12) for porous particles 5 within a specific particle size range D [μm] is performed. For setting the threshold values during sorting in Comparative Example 2 and Examples 1-3, a three-dimensional model was created by cutting out a part of the electrode plate as described above and using FIB-SEM or X-ray CT. The resulting particle weight W [g], particle size D [μm], and specific surface area S [m²] were determined. 2 / m 3 Based on the results of [ ], the particle sorting threshold was determined in advance.
[0088] Comparative Example 2 performed only the particle size sorting step (S12) for porous particles 5 within a specific particle size range D [μm], as in Patent Document 1. The weight sorting step (S11) for porous particles 5 within a specific particle weight range W [g] was not performed. In this case, the specific particle size range D [μm] was 0.9 to 1.1.
[0089] Example 1 involves performing only the weight sorting step (S11) for porous particles 5 within a specific particle weight range W[g], and not the particle size sorting step (S12) for porous particles 5 within a specific particle size range D[μm]. In this case, the specific particle weight range W[g] is 1.36 to 1.67.
[0090] Example 2 was carried out in the same manner as the sorting process of the first embodiment described above. The range of specific particle weight W [g] at this time was 1.36 to 1.67. The range of specific particle size D [μm] at this time was 1 to 1.25.
[0091] Example 3 was carried out in the same manner as the sorting process of the second embodiment described above. The range of specific particle weight W [g] at this time was 0.98 to 1.21. The range of specific particle size D [μm] at this time was 0.9 to 1.1.
[0092] Other conditions are as described in the embodiment. <Specific surface area S[m²] after sorting process 2 / m 3 Evaluation of the standard deviation of ] Specific surface area S[m 2 / m 3 To confirm that the variation in ] is narrowed, the specific surface area S[m 2 / m 3 The specific surface area S[m²] was calculated. In the calculation, as described above, a portion of the electrode plate was cut out and a 3D model that could be created using FIB-SEM or X-ray CT was used, and the value of the standard deviation was confirmed based on the particle characteristic distribution result. The smaller the value of this "standard deviation of specific surface area after sorting process", the less variation there is. In other words, the specific surface area S[m²] 2 / m 3 It can be seen that ] is more homogeneous.
[0093] <Experimental Results> First, Comparative Example 1 was used as the basis for comparison, and its specific surface area S[m²] after the sorting process was used. 2 / m 3 The standard deviation of ] is 100[%].
[0094] In Comparative Example 2, only particle size D [μm] was sorted, but compared to Comparative Example 1, the specific surface area S [m²] after the sorting process was 2 / m 3 The standard deviation of ] was 98[%]. Therefore, sorting by particle size D[μm] alone is almost not significant in terms of specific surface area S[m 2 / m 3 It can be seen that the variability of ] cannot be suppressed.
[0095] In Example 1, only particle weight W [g] was sorted, but compared to Comparative Example 1, the specific surface area S [m²] after the sorting process was different. 2 / m 3 The standard deviation of ] is 76[%], indicating a significant reduction in variability.
[0096] Example 2 is the result of the first embodiment described above. Specific surface area S[m²] after the sorting process. 2 / m 3 The standard deviation of ] was 51[%], which was roughly half that of Comparative Example 1. Therefore, according to the configuration of the first embodiment, the specific surface area S[m 2 / m 3 The variation in [ ] has decreased significantly.
[0097] Example 3 shows the results of the second embodiment. The sorting process in Example 3 is the same as in the first embodiment, sorting by both particle size D [μm] and particle weight W [g], but the order is different. Specific surface area S [m²] after the sorting process. 2 / m 3 The standard deviation of [ ] is 65[%], which is more variability than in Example 2. However, the variability is suppressed compared to Comparative Example 2, as well as Comparative Example 1.
[0098] <Summary of the experiment> First, compared to Comparative Example 1, which does not perform any sorting, if sorting is performed by particle size D [μm] as in Patent Document 1, the specific surface area S [m²] after the sorting process is increased. 2 / m 3 The standard deviation of ] was 98[%]. As a result, sorting by particle size D[μm] alone resulted in a specific surface area S[m 2 / m 3 It can be said that the variability in [ ] cannot be suppressed.
[0099] On the other hand, in Example 1, porous particles 5 are selected based solely on particle weight W [g], but the specific surface area S [m²] after the selection process is also considered. 2 / m 3 The standard deviation of ] was 76[%]. Therefore, even with sorting by particle weight W[g] alone, the specific surface area S[m 2 / m 3 The variability in [ ] can be said to be effectively suppressed.
[0100] Furthermore, in the configuration of the first embodiment, as in Example 2, after sorting by particle weight W [g], further sorting is performed by particle size D [μm]. As a result, the specific surface area S [m²] after the sorting process is 2 / m 3 The standard deviation of ] was 51[%]. Therefore, after sorting by particle weight W[g], further sorting by particle size D[μm] was performed to obtain the specific surface area S[m 2 / m 3 The variability in [ ] can be said to have been significantly suppressed.
[0101] In the configuration of the second embodiment, as in Example 3, after sorting by particle size D [μm], further sorting is performed by particle weight W [g]. As a result, the specific surface area S [m²] after the sorting process is 2 / m 3 The standard deviation of ] was 65[%]. Therefore, if the order of sorting by particle weight W[g] and sorting by particle size D[μm] is changed as in Example 3, the specific surface area S[m 2 / m 3 The variation in [ ] indicates that the inhibitory effect was reduced compared to Example 2.
[0102] In Example 1, only the weight sorting process (S11) is performed. As a result, porous particles 5 with relatively similar porosity P[%] are sorted. As a result, the specific surface area S[m 2 / m 3 The standard deviation of [ ] is considered to have become smaller compared to Comparative Example 1.
[0103] In Example 2, a weight sorting step (S11) is performed first. As a result, porous particles 5 with relatively similar porosity P[%] are selected. Furthermore, in the subsequent particle size sorting step (S12), the particle size D[μm] of the porous particles 5 is sorted. As a result, the porosity P[%] and particle size D[μm] are made uniform, and the specific surface area S[m²] is made uniform. 2 / m 3 It is thought that the standard deviation of [ ] has become even smaller compared to Comparative Example 1.
[0104] In Example 3, the porous particles 5 are first sorted by particle size D [μm] in a particle size sorting step (S12). Then, a weight sorting step (S11) is performed. As a result, porous particles 5 with relatively similar porosity P [%] are sorted. As a result, the porosity P [%] and particle size D [μm] are made more uniform, but the specific surface area S [m²] is more uniform. 2 / m 3 The weight sorting process (S11), which has a significant impact on the specific surface area S[m²], is performed after the particle size sorting process (S12). Therefore, the specific surface area S[m²] 2 / m 3 The standard deviation of [ ] appears to be slightly larger compared to Example 2.
[0105] (Operation of this embodiment) In the first embodiment, a sorting step is provided for sorting by particle size D [μm] and particle weight W [g]. The sorting step includes a "weight sorting step (Figures 2 and 3: S11)" in which the particle weight W [g] of the porous particles 5 to be used as raw materials is sorted so that it falls within a set range. In addition, a "particle size sorting step (Figures 2 and 3: S12)" is provided in which the particles are sorted so that they fall within a set range of particle size D [μm]. As a result, the porosity P [%] of the sorted porous particles 5 becomes uniform. Furthermore, the porosity P [%] and specific surface area S [m²] 2 / m 3There is a strong correlation with ], therefore the specific surface area S[m²] of the porous particles 5 after sorting. 2 / m 3 ] can also be made homogeneous.
[0106] Such a homogeneous specific surface area S[m 2 / m 3 By using porous particles 5 of the positive electrode active material as a raw material, a positive electrode plate 3 with uniform performance is manufactured. Furthermore, a lithium-ion secondary battery 1 is manufactured using such a positive electrode plate 3.
[0107] (Effects of this embodiment) (1) According to the method for manufacturing porous particles 5, the method for manufacturing a positive electrode plate 3 using porous particles 5, and the method for manufacturing a lithium-ion secondary battery 1, the specific surface area S[m 2 / m 3 This has the effect of being able to form homogeneous porous particles.
[0108] (2) The process includes a weight sorting step (S11) in which porous particles 5 to be used as raw materials are sorted so that the particle weight W [g] falls within a set range, and a particle size sorting step (S12) in which the porous particles 5 sorted by the weight sorting step are sorted so that the particle size D [μm] falls within a set range. This has the effect of making the particle weight W [g] and particle size D [μm] of the porous particles 5 to be used as raw materials homogeneous.
[0109] (3) In the first embodiment, the specific surface area S[m²] of the target porous particles 5 is relative to the particle weight W[g] of the porous particles 5 selected in the weight sorting step (S11). 2 / m 3 The system includes a step of determining the particle size D [μm] of the porous particles 5 such that ] and storing the corresponding relationship. Therefore, by selecting the particle size D [μm] of the porous particles 5, the target specific surface area S [m 2 / m 3 This has the effect of allowing you to do [this].
[0110] (4) In the particle size sorting step (S12), a threshold for particle size D [μm] is set based on the correspondence with the particle weight W [g] of the porous particles 5 after the weight sorting step (S11), and the particles are sorted. Therefore, the particle weight W [g] and particle size D [μm] work together to determine a more accurate specific surface area S [m²]. 2 / m 3 This has the effect of allowing you to do [this].
[0111] (5) In the second embodiment, the process includes a particle size sorting step (S12) in which porous particles 5 to be used as raw materials are sorted so that they fall within a set particle size range D [μm], and a weight sorting step (S11) in which the porous particles 5 sorted in the particle size sorting step are sorted so that their particle weight W [g] falls within a set range. This has the effect of making the particle weight W [g] and particle size D [μm] of the porous particles 5 to be used as raw materials homogeneous.
[0112] (6) The specific surface area S[m²] of the porous particles 5 selected in the particle size sorting process (S12) is the target specific surface area S[m²] of the porous particles 5. 2 / m 3 The process includes a step of determining the particle weight W[g] of the porous particle 5 such that ] and storing the corresponding relationship. Therefore, by selecting the particle weight W[g] of the porous particle 5, the target specific surface area S[m 2 / m 3 This has the effect of allowing you to do [this].
[0113] (7) The weight sorting process (S11) sorts the porous particles 5 after the particle size sorting process by setting a threshold for the particle weight W [μm] of the porous particles 5 based on the correspondence with the particle size D [μm] of the porous particles 5. Therefore, the particle size D [μm] and particle weight W [g] work together to determine a more accurate specific surface area S [m²]. 2 / m 3 This has the effect of allowing you to do [this].
[0114] (8) The weight sorting process (S11) sorts the porous particles 5, which are to be used as raw materials, using a cyclone-type classifier so that they have a particle weight W [g] that is a predetermined threshold. In this way, porous particles 5 with a particle weight W [g] that is within the predetermined threshold can be easily sorted during the manufacturing process.
[0115] (9) The particle size sorting step (S12) is performed by sorting using a screen-type classifier having a screen with a mesh size D [μm] that is a predetermined threshold particle size. Therefore, porous particles 5 with a particle size D [μm] that falls within the predetermined threshold can be easily sorted during the manufacturing process.
[0116] (10) Uniform specific surface area S[m 2 / m 3 The positive electrode active material, which is porous particles 5 of ], is incorporated into the positive electrode composite layer 32 of the positive electrode plate 3 to manufacture the positive electrode plate 3. Therefore, the specific surface area S[m 2 / m 3 This allows for uniform battery performance caused by [variables].
[0117] (Another example) In this embodiment, a positive electrode active material consisting of secondary particles was given as an example of porous particles 5, but the present invention is not limited thereto. For example, it can be widely implemented with porous particles 5 that have a certain function by utilizing their surface area, such as trilithium phosphate added to the positive electrode.
[0118] ○Particle weight [g], volume [m³] 3 ], specific surface area S[m 2 / m 3 Numerical values representing the characteristics of porous particles 5, such as those listed above, may indicate the average even if the term "average" is not explicitly used. The average basically refers to the median value (d50).
[0119] ○In this embodiment, the specific surface area is the specific surface area S[m²] based on volume. 2 / m 3 ] was used, but the specific surface area [m²] was based on weight. 2 You may also use / g]. ○In this embodiment, the particle weight W [g] was used as the "weight per unit amount" based on the weight of each porous particle 5, but the weight [g / m³] based on a certain volume was used instead. 3 You may also use [ ] etc.
[0120] In this embodiment, the lithium-ion secondary battery 1 is exemplified as a cell battery constituting a battery pack for vehicle propulsion, but the lithium-ion secondary battery 1 of the present invention is not limited in terms of its structure, composition, shape, etc. Furthermore, it can be implemented with other non-aqueous electrolyte secondary batteries, etc. It may also be applied to alkaline secondary batteries such as nickel-metal hydride secondary batteries.
[0121] The drawings are for reference to help understand the invention, but do not limit the invention. ○The numerical values, numerical ranges, compositions, etc., in this embodiment are illustrative and do not limit the present invention. They can be appropriately optimized and implemented by those skilled in the art.
[0122] The flowcharts shown in Figures 2, 3, and 9 are examples of implementation, and the steps may be added, deleted, rearranged, or modified. ○The present invention can be implemented by those skilled in the art with additions, deletions, and modifications, without departing from the scope of the claims. [Explanation of Symbols]
[0123] 1…Lithium-ion rechargeable battery 11…Battery case 12...Electrode body 13...Nonaqueous electrolyte 14…Positive external terminal 15…Negative external terminal 16…Positive current collection terminal 17... Negative current collection terminal 2… Negative plate 21... Negative electrode current collector foil 22...Negative electrode composite material layer 23…Negative electrode current collector (unpainted area) 3…Positive plate 31...Positive current collector foil 32…Positive electrode composite layer 33…Positive electrode current collector 4... Separator 5...Porous particles (positive electrode active material) 5a…particle 5b…Gap S[m 2 / m 3 ]…Specific surface area D(d50) [μm]... Particle size (median diameter) W[g]…Particle weight
Claims
1. A weight sorting process in which porous particles to be used as raw materials are sorted so that the weight per unit amount falls within a set range, A particle size sorting step is performed to sort the porous particles sorted by the weight sorting step so that they fall within a set particle size range. The process includes determining the particle size of the porous particles such that the weight per unit amount of the porous particles selected in the weight sorting step equals the target specific surface area of the porous particles, and storing the corresponding relationship. A method for producing porous particles, characterized in that the particle size sorting step involves sorting the porous particles after the weight sorting step by setting a threshold for the particle size based on the correspondence with the weight per unit amount of the porous particles.
2. A particle size sorting process in which porous particles to be used as raw materials are sorted to fall within a set particle size range, A weight sorting step is performed to sort the porous particles sorted in the particle size sorting step so that the weight per unit amount falls within a set range. The process includes determining the weight per unit amount of porous particles that corresponds to the target specific surface area of the porous particles with respect to the particle size of the porous particles selected in the particle size sorting step, and storing the corresponding relationship. A method for producing porous particles, characterized in that the weight sorting step involves sorting the porous particles after the particle size sorting step by setting a threshold weight per unit amount of the porous particles based on the correspondence with the particle size of the porous particles.
3. The aforementioned weight sorting process is, A method for producing porous particles according to claim 1 or 2, characterized in that the porous particles to be used as raw materials are sorted by a cyclone-type classifier so that the weight per unit amount is a set threshold.
4. The particle size sorting step is as follows: A method for producing porous particles according to claim 1 or 2, characterized in that the porous particles to be used as raw materials are sorted by a screen-type classifier having a screen with a mesh size of the particle size that is a set threshold.
5. A method for manufacturing an electrode using porous particles, wherein porous particles manufactured by the method for manufacturing porous particles described in claim 1 or claim 2 are incorporated into the composite layer of the electrode.
6. A method for manufacturing an electrode using porous particles according to claim 5, characterized in that the porous particles are a positive electrode active material.
7. A method for manufacturing an electrode using porous particles according to claim 5, characterized in that the porous particles are trilithium phosphate.
8. A method for manufacturing a secondary battery using an electrode manufactured by the electrode manufacturing method of claim 5.
9. The method for manufacturing a secondary battery according to claim 8, wherein the secondary battery is a lithium-ion secondary battery.