Electrode, electrode manufacturing method and battery

Abstract

The present invention discloses an electrode, a method for manufacturing the electrode, and a battery, the electrode including n electrode plate layers stacked in order, the electrode plate layer adjacent to a separator of the battery being a first layer, the electrode plate layer adjacent to a current collector of the battery being an nth layer, n being a natural number of 2 or more, the electrode material of the first electrode plate layer including first particles, the electrode material of each of the electrode plate layers from the second layer to the nth layer including at least first particles and second particles, the average particle size of the first particles being larger than the average particle size of the second particles, and the porosity of each of the electrode plate layers gradually increasing in the direction from the nth layer to the first layer.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to Chinese Patent Application No. 202110903844.7, entitled "Electrode, Electrode Manufacturing Method, and Battery," filed on August 6, 2021, the entire contents of which are incorporated herein by reference.

[0002] The present application relates to the technical field of battery assemblies, and more particularly to electrodes, methods of manufacturing electrodes, and batteries. [Background technology]

[0003] Lithium ion power battery is a new type of rechargeable high energy battery, which is mainly operated by lithium ions moving between positive and negative electrodes. The lithium ion power battery has the advantages of high energy, high battery voltage, wide operating temperature range, long storage life, etc., and is widely used in military and civilian small electrical equipment.

[0004] With the popularity of new energy vehicles, the application of lithium ion power batteries in the automotive field is becoming more and more widespread. The volumetric energy density of lithium ion power batteries is very important for vehicle use, and in the prior art, the volumetric energy density of the battery is usually improved by improving the packing density of the electrode. However, the ultimate packing density of the electrode is usually affected by the true density of the material itself, and under high packing density, the porosity of the electrode is extremely low, and the voids are easily blocked, especially on the surface of the electrode, making it difficult for lithium ions to diffuse, which greatly reduces the dynamic properties of the electrode. Summary of the Invention [Problem to be solved by the invention]

[0005] The present application aims to provide new technical means for an electrode, a method for manufacturing an electrode, and a battery. [Means for solving the problem]

[0006] An electrode according to a first aspect of the present application includes n electrode plate layers stacked in order, the electrode plate layer closest to a separator of a battery being a first layer, and the electrode plate layer closest to a current collector of the battery being an nth layer, where n is a natural number of 2 or more, the electrode material of the electrode plate layer of the first layer includes first particles, the electrode material of each of the electrode plate layers from the second layer to the nth layer includes at least first particles and second particles, the average particle size of the first particles is larger than the average particle size of the second particles, and the porosity of the electrode plate layer of each layer gradually increases along the direction from the nth layer to the first layer.

[0007] The method for manufacturing an electrode according to the first aspect of the present application includes the steps of: thoroughly mixing an electrode material, a conductive agent, and an adhesive to form a mixture; heating the mixture to bring the adhesive to a molten state; solidifying the molten adhesive and enveloping the electrode material in the solidified adhesive to obtain a powdered material; processing the powdered material to form the electrode layer; manufacturing a plurality of the electrode layers with different porosities by adjusting the quantity of first particles and second particles in the electrode layer of each layer as described above; and sequentially stacking and fusing the plurality of electrode layers according to the magnitude of the porosity to obtain the electrode.

[0008] A battery according to a third aspect of the present application comprises the electrode according to the first aspect.

[0009] According to an embodiment of the present disclosure, the separator side electrode layer is manufactured using first particles, and the remaining electrode layers are manufactured using first particles and second particles having different particle sizes, thereby improving the packing density of the electrode. At the same time, a plurality of electrode layers are arranged such that the porosity of each layer increases gradually from the current collector side to the separator side, thereby improving the diffusion efficiency of lithium ions and the dynamic properties of the electrode.

[0010] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application, taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0011] The drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the present application and, together with the description, explain the principles of the present application.

[0012] [Figure 1] FIG. 1 is a schematic diagram of an electrode and its manufacturing process according to the present application. [Diagram 2] FIG. 1 is a schematic diagram of a battery according to the present application. [Diagram 3] 2 is a flowchart of a method for manufacturing an electrode according to the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Various exemplary embodiments of the present application will be described in detail below with reference to the drawings. It should be noted that, unless otherwise specified, the relative arrangement of the components and steps described in these embodiments, numerical expressions and values ​​do not limit the scope of the present application.

[0014] The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the present application and its application or uses.

[0015] Techniques, methods and apparatus known to those skilled in the art may not be described in detail, but these techniques, methods and apparatus should be considered as part of the specification, where appropriate.

[0016] In all examples shown and discussed herein, any specific values ​​should be construed as exemplary only and not limiting, and thus other examples of the example embodiments may have different values.

[0017] It should be noted that like reference numbers and letters represent like elements in the following drawings, so that once any element is defined in one drawing, it need not be discussed further in subsequent drawings.

[0018] In the prior art, the volumetric energy density of a battery is usually improved by improving the packing density of the electrode, but a high packing density of the electrode reduces the porosity of the electrode, and the voids on the surface of the electrode are easily blocked. The number of voids in the electrode directly affects the charge and discharge performance of the battery, and a low or blocked porosity affects the movement of lithium ions and greatly reduces the dynamic properties of the electrode. Therefore, the electrode structure requires not only high pressure but also a reasonable void structure. The porosity refers to the percentage of the void volume in the material and the total volume of the material in the natural state.

[0019] As shown in Figures 1 and 2, in order to solve the above technical problem, the electrode of the present application includes n electrode plate layers stacked in order, the electrode plate layer on the side closest to the separator of the battery is a first layer 13, and the electrode plate layer on the side closest to the current collector of the battery is an nth layer 14, where n is a natural number of 2 or more, the electrode material of the electrode plate layer of the first layer 13 includes a first particle 11, and the electrode material of each of the electrode plate layers from the second layer to the nth layer includes at least the first particle 11 and the second particle 12, the average particle diameter of the first particle 11 is larger than the average particle diameter of the second particle 12, and the porosity of the electrode plate layer of each layer gradually increases along the direction from the nth layer 14 to the first layer 13.

[0020] Specifically, in this embodiment, the electrode has a structure in which a plurality of (n layers) electrode plate layers are stacked (n is a natural number of 2 or more, i.e., the electrode may include two, three, or even more layers, and the present application is not limited thereto), and such a structure is advantageous for distinguishing and setting the characteristics of the electrode material of each electrode plate layer. After stacking and installing a plurality of electrode plate layers, the electrode materials of the first layer 13 electrode plate layer and the nth layer 14 electrode plate layer located on both sides of the electrode are determined (when the electrode is applied to a battery, a current collector and a separator are usually installed on both sides of the electrode, and the electrode plate layer closest to the current collector is the nth layer 14, and the electrode plate layer closest to the separator is the first layer 13). The electrode material includes first particles 11 and second particles 12, and the average particle size of the first particles 11 is larger than the average particle size of the second particles 12. The electrode material of the first layer 13 may include only the first particles 11, and the electrode material of the remaining electrode layers (second layer to nth layer) may include the first particles 11 (large particles) and the second particles 12 (small particles). The combination of large and small particles allows the small particles to fill the gaps between the large particles to achieve a higher compaction density. The remaining electrode layers refer to the electrode layers other than the first layer 13, that is, if the electrode has a total of two electrode layers, the remaining electrode layer is the second electrode layer, and the electrode material of the second electrode layer includes at least the first particles 11 and the second particles 12; if the electrode has three electrode layers, the remaining electrode layers are the second electrode layer and the third electrode layer, and the second electrode layer and the third electrode layer include at least the first particles 11 and the second particles 12, and so on.

[0021] In addition, by adjusting the quantity of large particles and small particles in the remaining electrode plate layers (the second layer to the nth layer), the porosity of each electrode plate layer can be controlled to gradually increase from the nth layer 14 to the first layer 13. That is, the electrode plate layer of the nth layer 14 has the lowest porosity, and the separator layer side has a larger void and a higher porosity, which facilitates the diffusion of lithium ions and provides the electrode with a lower impedance and a higher rate of discharge retention. In addition, the more the number of electrode plate layers is, the more uniform the gradient distribution of the voids (i.e., the change rule in which the porosity gradually increases from the nth layer 14 to the first layer 13) becomes, which is favorable for the diffusion of lithium ions. The particle size of the first particles 11 selected from each electrode plate layer may be different, and the particle size of the second particles 12 selected from the second layer to the nth layer may also be different accordingly, making it easy to configure electrode plate layers of different porosities. The diffusion of lithium ions is limited by layers with low porosity, and when an electrode includes n plate layers, in terms of porosity and compaction density, in actual production, the proportion of first particle 11 (large particle) material in the plate layer of the first layer 13 and the plate layer of the nth layer 14 of the electrode is first determined, and the porosity of the plate layer of the intermediate layer can be further adjusted to present a uniform gradient.

[0022] As a result, the electrode in this embodiment has a high compaction density, which improves the volumetric energy density of the lithium ion battery. Due to the gradient change rule of the porosity between the first layer 13 and the nth layer 14, the electrode in this technical solution also has high dynamic properties.

[0023] Preferably, when the ratio of the number of the first particles 11 contained in the xth electrode plate layer to the electrode material of the layer is a, a=m(1st particle) / m(all particles)=[-x / (2n-2)+(2n-1) / (2n-2)](1) Here, n is a natural number equal to or greater than 2, x is a natural number equal to or less than n, and m is the number of particles.

[0024] Specifically, the porosity of each electrode layer can be achieved by adjusting the quantity of the first particles 11 and the second particles 12 of each layer. By adjusting the quantity of the large particles and the small particles, the gradient change of the porosity of each electrode layer can be achieved, which is easy to achieve in actual manufacturing, and the adjustment result is relatively accurate. For example, in an electrode having two electrode layers, the ratio of the first particles 11 in the electrode layer of the first layer 13 is 100%, and the ratio of the first particles 11 in the electrode layer of the second layer is 50%. Also, for example, in an electrode having four electrode layers, the ratio of the first particles 11 in the electrode layer of the first layer is 100%, the ratio of the first particles 11 in the electrode layer of the second layer is 83.3%, the ratio of the first particles 11 in the electrode layer of the third layer is 66.7%, and the ratio of the first particles 11 in the electrode layer of the fourth layer is 50%. By setting the quantity of the first particles 11 according to the above rules summarized in this application, the quantity of the first particles 11 in the electrode layer of the nth layer 14 can be always maintained at least equal to or greater than 50%, thereby ensuring that the porosity of each electrode layer is not too low.

[0025] Preferably, the average particle size range of the first particles 11 is 0.90 μm to 1.60 μm, and the average particle size range of the second particles 12 is 0.25 μm to 0.70 μm.

[0026] Specifically, in this embodiment, the average particle size range of the first particles 11 is 0.90 μm to 1.60 μm, and the average particle size range of the second particles 12 is 0.25 μm to 0.70 μm. If the average particle size of the first particles 11 or the second particles 12 is too large, the specific surface area of ​​the particles is small, the solid-phase diffusion path is long, the kinetics of the electrochemical reaction of the material is slowed, and the kinetic characteristics of the battery are affected. If the average particle size of the first particles 11 or the second particles 12 is too small, the specific surface area of ​​the particles is large, and the electrochemically active area is also large accordingly, and the number of side reactions occurring on the surface of the particle material increases, and the cycle performance of the battery is impaired. The electrochemically active area refers to the part of the particle surface that can participate in the electrochemical reaction. Preferably, the average particle size range of the first particles 11 is 1.0 μm to 1.2 μm, and the average particle size range of the second particles 12 is 0.35 μm to 0.55 μm.

[0027] Preferably, the radius of the first particle 11 is R and the radius of the second particle 12 is less than or equal to 0.414R.

[0028] Specifically, in this embodiment, the electrode materials used can be regarded as substantially spherical particles. Even if particles of the same particle size are densely stacked, there are gaps between the particles, and by filling the gaps with smaller particles, the compaction density of the material can be increased. That is, when the first particles 11 are densely stacked, when the radius of the first particles 11 is R, the maximum radius that can be accommodated in the gaps of the first particles 11 is 0.414R. Therefore, when the radius r of the second particles 12 is ≦ 0.414R, the gaps between the first particles 11 can be smoothly filled. Such a combination of materials has an ultra-high pressure compaction density, and the material combined at such an ultra-high pressure compaction density can be used as the electrode plate layer of the nth layer 14, and then the filling amount of the second particles 12 (small particles) is gradually reduced from the electrode plate layer of the nth layer 14 to the electrode plate layer of the first layer 13, gradually improving the porosity of each layer, and a gradient pore structure that is favorable for the diffusion of lithium ions can be formed. Such an electrode structure can achieve both high compaction density and high particle diffusion efficiency.

[0029] Preferably, each of the electrode layers from the second layer to the n-th layer further includes third particles, and the maximum radius of the third particles is 0.225R or less.

[0030] Specifically, in this embodiment, other than the first layer 13 electrode layer using the first particle 11, the other electrode layers may be made of three kinds of particle materials with different sizes. For example, the nth layer 14 electrode layer may be made of the first particle 11, the second particle 12 and the third particle. In this case, compared with the two kinds of particle materials in the above embodiment, the maximum radius of the third particle is 0.225R. The electrode layer formed by the three kinds of particle materials with different sizes has a higher compaction density. After adjusting the material of the nth layer 14 electrode layer, the filling amount of the second particle 12 and / or the third particle can be gradually reduced from the nth layer 14 electrode layer to the first layer 13 electrode layer to gradually improve the porosity of each layer and form a gradient pore structure that is favorable for the diffusion of lithium ions. The use of three kinds of particle materials can not only make the compaction density of the electrode larger, but also makes it easier to adjust the gradient of the change in porosity, which is favorable for realizing a uniform change in the pore structure of each layer.

[0031] Preferably, the particle size of the first particle 11 and the particle size of the second particle 12 used in the xth electrode layer are 1 / d 11 =[a*d x1 2 +(1-a)d x2 2 ] / [a*d x1 3 +(1-a)d x2 3 ](2) It satisfies the condition that Here, x is a natural number greater than 1 and less than or equal to 2, a is the ratio of the number of the first particles 11 in the xth layer to the electrode material of the layer, and d 11 represents the particle size of the first particle 11 in the electrode layer of the first layer 13, and d x1 represents the particle size of the first particle 11 in the xth electrode layer, and d x2 represents the particle size of the second particle 12 in the xth layer.

[0032] Usually, when the particles of the electrode material become smaller, the tortuosity σ of the electrode becomes larger, which is unfavorable to particle diffusion. In this embodiment, when the first particles 11 and the second particles 12 are blended, the tortuosity σ of the electrode plate layer of each layer can be made close to each other by adjusting the particle size of the first particles 11 and the second particles 12 of each layer. That is, the particle size of the first particles 11 in the electrode plate layer of the first layer 13 may be different from the particle size of the first particles 11 in the remaining electrode plate layers from the second layer to the nth layer. When the average particle size of the first particles 11 and the second particles 12 in the electrode plate layer of each layer satisfies formula (2), it can be ensured that the tortuosity σ of the electrode plate layer of each layer is close to each other, which makes the electrode characteristics more uniform, is favorable to the diffusion of lithium ions, and further improves the ion diffusion efficiency. The tortuosity σ is a parameter that describes the electrode channel structure, and the greater the tortuosity, the more the internal channel is bent, and the longer the path for ions to diffuse from the surface to the current collector.

[0033] Preferably, the number of layers of the electrode plate layers ranges from 2 to 10 layers, and the number of second particles 12 contained in the electrode material of each of the remaining electrode plate layers other than the first layer 13 gradually decreases in the direction from the side closest to the current collector to the side closest to the separator.

[0034] Specifically, in this embodiment, in order to form a uniform void structure, the number of electrode plate layers can be selected to be 2 to 10 layers. If the number of electrode plate layers is too large, the change in porosity between two adjacent layers becomes small, and if the gradient change in porosity is too small, there is no particularly clear effect on improving the diffusion of lithium ions, but the impact on production efficiency becomes large. Therefore, the selection of an appropriate number of layers can achieve both the gradient change in porosity and production efficiency. In addition, the gradient adjustment of porosity can be realized by adjusting the ratio of the second particles 12 in each layer.

[0035] Preferably, the electrode material comprises a positive electrode material, the positive electrode material being at least one of lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium manganate.

[0036] Specifically, the electrode according to this embodiment may be manufactured as a positive electrode of a battery by using a positive electrode material, or as a negative electrode of a battery by using a negative electrode material. The positive electrode material may be at least one of lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium manganese oxide, and the negative electrode material may be at least one of artificial graphite, natural graphite, lithium titanate, soft carbon, and hard carbon.

[0037] The advantages of the electrode according to the first embodiment will be further described below with reference to several examples and comparative examples. EXAMPLES

[0038] A two-layer electrode solution is used, and lithium iron phosphate material is selected as the electrode material. In the second electrode layer, the first particles 11 (average particle size D50=1.38 μm) and the second particles 12 (average particle size D50=0.57 μm) are mixed at 1:1, with a mass ratio of 93:7, and in the first electrode layer 13, the first particles 11 (average particle size D50=1.26 μm) are used. EXAMPLES

[0039] Using the solution of the three-layer electrode, lithium iron phosphate material is selected as the electrode material. In the third layer of the electrode plate layer, the first particles 11 (average particle size D50 = 1.38 μm) and the second particles 12 (average particle size D50 = 0.57 μm) are mixed at 1:1, with a mass ratio of 93:7; in the intermediate second layer of the electrode plate layer, according to the above-mentioned design rules, the average particle size of the first particles 11 is 1.30 μm, the average particle size of the second particles 12 is 0.53 μm, with a mass ratio of 97:3; in the first layer 13 of the electrode plate layer, the first particles 11 (average particle size D50 = 1.26 μm) are used. EXAMPLES

[0040] Using the solution of the three-layer electrode, lithium iron phosphate material is selected as the electrode material. In the third layer of the electrode plate layer, the first particles 11 (average particle size D50 = 1.19 μm) and the second particles 12 (average particle size D50 = 0.493 μm) are mixed at 1:1, with a mass ratio of 93:7. In the intermediate second layer of the electrode plate layer, according to the above-mentioned design rules, the average particle size of the first particles 11 is 1.12 μm, the average particle size of the second particles 12 is 0.466 μm, with a mass ratio of 97:3. In the first layer 13 of the electrode plate layer, the first particles 11 (average particle size D50 = 1.09 μm) are used. Comparative Example 1

[0041] Using the two-layer electrode solution, lithium iron phosphate material is selected as the electrode material. In the second electrode layer, the first particle (average particle size D50 = 1.26 μm) is used, and in the first electrode layer, the first particle (average particle size D50 = 1.38 μm) and the second particle (average particle size D50 = 0.57 μm) are mixed in a 1:1 ratio, with a mass ratio of 93:7. Comparative Example 2

[0042] Using the solution of single-layer electrode, lithium iron phosphate material is selected as the electrode material. The first particles (average particle size D50=1.38μm) and the second particles (average particle size D50=0.57μm) are mixed in a 1:1 ratio, and the mass ratio is 96:4. Comparative Example 3

[0043] A single-layer electrode solution is used, and lithium iron phosphate material with an average particle size of D50=1.38 μm is used as the electrode material.

[0044] The above examples and comparative examples yielded the following data tables. [Table 1]

[0045] Table 1 shows the compaction density corresponding to an electrode with a width of 5 cm at a rolling pressure of 1 MPa, and it can be seen that the multilayer coating design allows the compaction density of the electrode plate to be maintained at a relatively high level, despite the addition of small particles (second particles 12). [Table 2]

[0046] Table 2 shows that the electrodes designed according to gradient porosity with multi-layer coating have higher capacity performance with the same design parameters. [Table 3]

[0047] Table 3 shows that under the condition of 50% SOC DC internal resistance, the electrode according to the present invention has lower impedance, which is favorable for the diffusion of lithium ions. [Table 4]

[0048] Table 4 shows that under the condition of 0.2 / 2C discharge capacity ratio at room temperature, the electrode according to the present invention has a higher rate of discharge maintenance rate and is favorable for the diffusion of lithium ions.

[0049] As shown in FIG. 3, the method for producing an electrode according to the first aspect of the present application includes the steps of: thoroughly mixing an electrode material, a conductive agent, and an adhesive to form a mixture; heating the mixture to bring the adhesive to a molten state; solidifying the molten adhesive and enveloping the electrode material in the solidified adhesive to obtain a powdered material; processing the powder material to form the plate layer; As described above, by adjusting the quantity of the first particles 11 and the second particles 12 in each of the electrode layers, a plurality of the electrode layers having different porosities are manufactured; and stacking and fusing a plurality of the electrode layers in order according to the magnitude of the porosity to obtain the electrode.

[0050] Specifically, taking the manufacture of a battery positive electrode as an example, first, according to the solution of the first aspect, a positive electrode material with an appropriate particle size is selected, the positive electrode material is pulverized into particles, and the particles are thoroughly mixed with a conductive agent and an adhesive to form a mixture. The positive electrode material can be selected from lithium iron phosphate, lithium nickel cobalt manganese oxide, lithium manganese oxide, etc., and the conductive agent includes carbon nanotubes, graphene, carbon black, carbon fiber, etc. The mixture is heated to melt the adhesive therein, and then solidified to fully envelop the particle material in the adhesive to form a powdery material. The powdery material is processed to form a base plate with a certain size and thickness, and such a base plate is the plate layer that will finally be processed into an electrode. Depending on the magnitude of the porosity, the manufactured multiple plate layers are stacked and fused to finally obtain an electrode with a high compaction density and a uniformly changing porosity.

[0051] When manufacturing the first layer 13 of the electrode plate layer, only the first particle 11 needs to be added to the electrode material, and the remaining layers can be added with the first particle 11, the second particle 12, the third particle, etc. according to the actual needs based on the technical means of the first embodiment. The ratio of the quantity of the first particle 11 and the second particle 12 in each electrode plate layer can be determined according to formula (1), and the particle size of the first particle 11 and the second particle 12 in each electrode plate layer can be determined according to formula (2). The electrode manufactured by the manufacturing method of the present application has ultra-high pressure compaction, so as to improve the volumetric energy density of the battery. The porosity of the electrode plate layers from the first layer 13 to the nth layer 14 of the electrode has a certain gradient change rule, and the dynamic properties of the electrode can be guaranteed at the same time. The entire manufacturing process is simple and the manufacturing efficiency is high.

[0052] Preferably, solidifying the molten adhesive comprises solidifying the adhesive into fibers by an electrospinning process.

[0053] Specifically, when the adhesive in a molten state is solidified, the electrospinning process can be selected. Electrospinning is a special form of electrostatic atomization of polymer fluid, in which the atomized and split material is not a microdroplet but a microjet of polymer, which can travel a fairly long distance and finally solidify into fibers. In this way, the polymer filaments with a nano-order diameter can be produced, making the adhesion between the adhesive and the particles of the electrode material stronger and more uniform.

[0054] Preferably, the process of sequentially stacking and fusing a plurality of the electrode layers includes a hot pressing process.

[0055] Specifically, the hot pressing process can achieve a high compaction density of the particulate material, while making the fusion of each layer more complete and the integrity of the electrode stronger.

[0056] A battery according to a third aspect of the present application comprises the electrode according to the first aspect.

[0057] Preferably, the battery includes a first current collector, a first electrode 1, a separator, a second electrode 2 and a second current collector arranged in this order, and an electrolyte is filled between the first electrode 1 and the separator, and between the second electrode 2 and the separator, respectively.

[0058] As shown in FIG. 2, the battery according to this embodiment includes a first current collector 4, a first electrode 1, a separator 3, a second electrode 2, and a second current collector 5, which are arranged in this order. An electrolyte 6 is filled between the first electrode 1 and the separator 4, and between the second electrode 2 and the separator 4. The first electrode 1 is a negative electrode, and the second electrode 2 is a positive electrode, both of which use the electrode structure described in the first embodiment. During assembly, the electrode plate layers of the first layer 13 of the first electrode 1 and the second electrode 2 are both arranged adjacent to the separator 3, and the electrode plate layers of the n-th layer 14 are respectively adjacent to the first current collector 4 and the second current collector 5. The first current collector 4 may be made of copper foil, and the second current collector 5 may be made of aluminum foil. The battery according to this embodiment has higher volumetric energy density and kinetic properties.

[0059] In the above embodiments, the description focuses on the differences between each embodiment, and the different optimal features between each embodiment can be combined to form a more preferred embodiment, unless they are inconsistent, and for the sake of brevity, the description will be omitted here.

[0060] Although some specific embodiments of the present application have been described in detail with reference to examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is limited by the appended claims. [Explanation of symbols]

[0061] 1 1st electrode 11 1st particle 12 2nd particle 13 1st layer 14 nth layer 2 2nd electrode 3. Separator 4 First current collector 5 Second current collector 6 Electrolyte

Claims

1. An electrode applied to a battery, comprising n layers of electrode plate layers laminated in sequence, wherein the electrode plate layer on the side close to the separator of the battery is the first layer, and the electrode plate layer on the side close to the current collector of the battery is the nth layer, and n is a natural number of 2 or more, the electrode material of the electrode plate layer of the first layer contains first particles, and the electrode materials of the electrode plate layers of each layer from the second layer to the nth layer each contain at least first particles and second particles, in any layer, the average particle size range of the first particles is 0.90 μm to 1.60 μm, and the average particle size range of the second particles is 0.25 μm to 0.70 μm, the mass ratio of the first particles in the electrode material of each layer gradually increases layer by layer in the direction from the nth layer to the first layer, the porosity of each of the electrode plate layers gradually increases layer by layer in the direction from the nth layer to the first layer. An electrode characterized by this.

2. When x is a natural number less than or equal to n, the ratio of the number of the first particles contained in the electrode plate layer of any xth layer to the electrode material of the xth layer is [-x / (2n - 2) + (2n - 1) / (2n - 2)]. The electrode according to Claim 1, characterized by this. The average particle size range of the first particles is 0.90 μm to 1.60 μm, and the average particle size range of the second particles is 0.25 μm to 0.70 μm.

3. The average particle size range of the first particles is 1.0 μm to 1.2 μm, and the average particle size range of the second particles is 0.35 μm to 0.55 μm. The electrode according to Claim 1, characterized by this.

4. The radius of the first particles is R, and the radius of the second particles is 0.414R or less. The electrode according to Claim 1, characterized by this.

5. Each of the electrode plate layers from the second layer to the nth layer further contains third particles, and the radius of the third particles is 0.225R or less. The electrode according to Claim 4, characterized by this.

6. The particle size of the first particles and the particle size of the second particles used in the electrode plate layer of any xth layer satisfy the condition of 1 / d11 = [a*dx12 + (1 - a)dx22] / [a*dx13 + (1 - a)dx23], Here, x is greater than 1 and less than or equal to n, a is the ratio of the number of the first particles in the x-th layer to the electrode material of the x-th layer, d11 represents the particle size of the first particles in the electrode plate layer of the first layer, dx1 represents the particle size of the first particles in the electrode plate layer of the x-th layer, and dx2 represents the particle size of the second particles in the x-th layer. The electrode according to claim 1, characterized in that.

7. The number of layers of the electrode plate layer ranges from 2 to 10 layers, and the number of the second particles contained in the electrode material of each of the remaining electrode plate layers other than the first layer gradually decreases layer by layer in the direction from the side close to the current collector to the side close to the separator. The electrode according to claim 1, characterized in that.

8. The electrode material includes a positive electrode material, and the positive electrode material is at least one of lithium iron phosphate, lithium nickel cobalt manganese oxide, and lithium manganate. The electrode according to claim 1, characterized in that.

9. The electrode material includes a negative electrode material, and the negative electrode material is at least one of artificial graphite, natural graphite, lithium titanate, soft carbon, and hard carbon. The electrode according to claim 1, characterized in that.

10. A method for manufacturing an electrode applied to the electrode according to any one of claims 1 to 9, A step of sufficiently mixing an electrode material, a conductive agent, and an adhesive to form a mixture; A step of heating the mixture to make the adhesive in a molten state; A step of solidifying the adhesive in the molten state and wrapping the electrode material with the solidified adhesive to obtain a powdery substance; A step of processing the powdery substance to form the electrode plate layer; As described above, by adjusting the quantities of the first particles and the second particles in each layer of the electrode plate layer, a step of manufacturing a plurality of the electrode plate layers with different porosities; A step of stacking and fusing a plurality of the electrode plate layers in order according to the magnitude of the porosity to obtain the electrode. A method for manufacturing an electrode, characterized by including.

11. The step of solidifying the adhesive in the molten state includes a step of solidifying the adhesive by an electrospinning process to make it fibrous. The method for manufacturing an electrode according to claim 10, characterized in that.

12. The process of stacking and fusing a plurality of the electrode plate layers in order includes a hot press process. The method for manufacturing an electrode according to claim 10, characterized in that.

13. A battery comprising the electrode according to any one of claims 1 to 9.

14. A battery comprising a first current collector, a first electrode, a separator, a second electrode, and a second current collector arranged in sequence, wherein electrolytes are filled between the first electrode and the separator and between the second electrode and the separator, and the first electrode and / or the second electrode is the electrode according to any one of claims 1 to 9.

Images