Lithium ion battery pole piece and preparation method thereof
Lithium-ion battery pole pieces are prepared through a multi-layer coating process, using a mixture of different particle sizes and conductive agents to form a multi-layer composite structure, which solves the contradiction between high energy density and low impedance and achieves high energy density and low impedance performance of lithium-ion battery pole pieces.
Patent Information
- Application Number
- CN202510792520.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-13
- Publication Date
- 2025-09-05
AI Technical Summary
In the process of pursuing high energy density, existing lithium-ion battery electrodes face the problem of high impedance, which affects the performance of the battery cell.
A multi-layer coating process is used to prepare lithium-ion battery pole pieces, including current collectors, first layer structures, transition layers, and second layer structures. A multi-layer composite structure is formed using a mixture of different particle sizes, combined with different types of conductive agents and adhesives to optimize the thickness and addition amount of each layer.
A lithium-ion battery electrode with low impedance and good structural stability is achieved, which has the performance of high energy density.
Smart Images
Figure CN120600754A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of secondary batteries, and in particular to a lithium-ion battery pole piece and a preparation method thereof. Background Art
[0002] As electronic devices continue to evolve toward lightweight and long battery life, the design of lithium-ion battery cells, which serve as power sources, is also moving toward higher energy density. This means that more active material must be packed into a cell of the same volume, leading to higher surface and compaction densities for lithium-ion battery electrodes. However, high surface and compaction densities increase the cell's impedance, impacting its performance.
[0003] Therefore, how to provide a lithium-ion battery electrode with high energy density and low impedance and a preparation method thereof. Summary of the Invention
[0004] The purpose of the present invention is to solve the above problems and provide a lithium-ion battery pole piece with high energy density and low impedance and a preparation method thereof; the lithium-ion battery pole piece is obtained by adopting a thick electrode material obtained by a multi-layer coating process, which can enable the lithium-ion battery made using the lithium-ion battery pole piece obtained by the present invention to have the performance of high energy density and low impedance.
[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:
[0006] In a first aspect, the present invention provides a lithium-ion battery electrode, comprising a current collector and an electrode active layer disposed on the surface of the current collector; wherein the electrode active layer comprises a first layer structure and a second layer structure sequentially coated on the surface of the current collector, and a transition layer is formed between the first layer structure and the second layer structure; the electrode active layer comprises a main material, a conductive agent, and an adhesive, the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure and the second layer structure, respectively, and the transition layer comprises the first mixture and the second mixture.
[0007] Optionally, the particle size of the first mixture is 5-25 μm, and the particle size of the second mixture is 0.5-5 μm.
[0008] Optionally, the thickness of a single layer of the first layer structure is 40-95 μm, the thickness of a single layer of the second layer structure is 50-110 μm, and the thickness of a single layer of the transition layer is 40-95 μm.
[0009] Optionally, the conductive agent includes a first conductive agent, a second conductive agent and a third conductive agent, which are respectively arranged in the first layer structure, the second layer structure and the transition layer; in terms of mass percentage, the amount of the first conductive agent added to the first layer structure is 0.3%-1.0%, the amount of the second conductive agent added to the second layer structure is 0.01%-0.3%, and the amount of the third conductive agent added to the transition layer is 0.03%-0.75%.
[0010] Optionally, the first conductive agent includes a conductive carbon black conductive agent, the second conductive agent includes a graphene conductive agent, and the third conductive agent includes a composite conductive agent formed by a conductive carbon black conductive agent and a carbon nanotube conductive agent; in terms of mass, the ratio of the added amount of the composite conductive agent formed by the conductive carbon black conductive agent and the carbon nanotube conductive agent in the third conductive agent is 1.5-33:1.
[0011] Optionally, when the lithium-ion battery electrode is a positive electrode, the amount of the adhesive added to the first layer structure, the second layer structure and the third layer structure is 1%-2%, 1.5%-2.5% and 1.2%-2.2% respectively, in terms of mass percentage.
[0012] Optionally, when the lithium-ion battery electrode is a negative electrode, the amount of the adhesive added to the first layer structure, the second layer structure and the third layer structure is 1.5%-2%, 2.0%-2.5% and 1.8%-2.2% respectively, in terms of mass percentage.
[0013] Optionally, the main material includes one or more of lithium ferrous phosphate, lithium cobalt oxide or lithium manganese oxide, and the adhesive is selected from one or both of PVDF and SBR.
[0014] Optionally, when the lithium-ion battery electrode is a positive electrode, the current collector includes aluminum foil; when the lithium-ion battery electrode is a negative electrode, the current collector includes copper foil.
[0015] In a second aspect, the present invention provides a method for preparing a lithium-ion battery pole piece, which is used to prepare the lithium-ion battery pole piece as described above, comprising the steps of:
[0016] providing a current collector;
[0017] An electrode active layer is formed by coating the surface of the current collector; the electrode active layer includes a first layer structure, a transition layer and a second layer structure coated in sequence on the surface of the current collector; the electrode active layer includes a main material, a conductive agent and an adhesive, and the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure and the second layer structure respectively, and the transition layer includes a third mixture formed by mixing the first mixture and the second mixture.
[0018] The beneficial effects produced by the present invention include at least:
[0019] The lithium-ion battery pole piece of the present invention includes an electrode active layer comprising the first structural layer, the transition layer, and the second structural layer sequentially formed on the surface of the current collector, resulting in a thick electrode material having a multi-layer composite structure. The first structural layer and the second structural layer are formed from the first mixture and the second mixture, respectively, having different particle sizes. The lithium-ion battery pole piece of the present invention is a thick electrode material with low impedance and excellent structural stability. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 It is a schematic structural diagram of the lithium-ion battery electrode of the present invention.
[0021] Among them, 1-current collector, 2-electrode active layer, 21-first layer structure, 211-first conductive agent, 22-transition layer, 221-third conductive agent, 23-second layer structure, 231-second conductive agent. DETAILED DESCRIPTION
[0022] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.
[0023] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.
[0024] In the present invention, descriptions such as “first”, “second”, etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features.
[0025] Example:
[0026] In the first aspect, the embodiment of the present invention provides a lithium ion battery electrode, see Figure 1 As shown, it includes a current collector 1 and an electrode active layer 2 provided on the surface of the current collector 1; wherein, the electrode active layer 2 includes a first layer structure 21, a transition layer 22 and a second layer structure 23 provided in sequence on the surface of the current collector 1; the electrode active layer 2 includes a main material, a conductive agent and an adhesive, and the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure 21 and the second layer structure 23 respectively, and the transition layer 22 includes a third mixture formed by mixing the first mixture and the second mixture.
[0027] The lithium-ion battery pole piece of the present invention includes an electrode active layer 2, and the electrode active layer 2 includes the first structural layer, the transition layer 22 and the second structural layer sequentially formed on the surface of the current collector 1, so as to obtain a thick electrode material with a multi-layer composite layer structure; the first structural layer 21 and the second structural layer are respectively formed by the first mixture and the second mixture of different particle sizes, the particle size of the first mixture is larger than the particle size of the second mixture, and the particle size of the particles in the mixture farther away from the surface of the current collector 1 is smaller. The smaller the particle size, the better the solid-phase migration of lithium ions. Conversely, the migration of lithium ions with large particles is worse. The first structural layer with larger particle size is arranged close to the current collector 1, which is more convenient for electron gain and loss and reduces The impedance of the thick electrode is reduced; the transition layer 22 includes a third mixture formed by mixing the first mixture and the second mixture, and the particles of large and small sizes are mixed, which reduces the contact impedance of the large and small particles, further reducing the impedance of the thick electrode; in addition, the particles of the first layer structure 21 in contact with the current collector 1 have a larger particle size, which makes the surface roughness of the first layer structure 21 greater and the bonding force between the first layer structure 21 and the current collector 1 greater, ensuring the bonding strength between the first layer structure 21 and the current collector 1, and further ensuring the structural stability of the lithium-ion battery pole piece. The bonding force between the first layer structure 21 and the current collector 1 in the lithium-ion battery pole piece provided by the present invention is greater than 5N / m. Therefore, the lithium-ion battery pole piece of the present invention is a thick electrode material with low impedance, good structural stability, and high energy density.
[0028] Optionally, the particle size of the first mixture is 5-25 μm, and the particle size of the second mixture is 0.5-5 μm. It should be noted that the particle size in the present invention refers to the average particle size of the particles in the mixture.
[0029] Optionally, the thickness of a single layer of the first layer structure 21 is 40-95 μm, the thickness of a single layer of the second layer structure 23 is 50-110 μm, and the thickness of a single layer of the transition layer 22 is 40-95 μm.
[0030] It should be noted that the single-layer thickness described in the present invention refers to the uncompacted thickness of each layer structure after drying. It is understood that the electrode active layer 2 includes at least one first layer structure 21, at least one second layer structure 23, and at least one transition layer 22. The present invention does not specifically limit the number of layers of the first layer structure 21, the second layer structure 23, and the transition layer 22. In actual use, the number can be set according to actual needs.
[0031] Optionally, the conductive agent includes a first conductive agent 211, a second conductive agent 231 and a third conductive agent 221, which are respectively arranged in the first layer structure 21, the second layer structure 23 and the transition layer 22; in terms of mass percentage, the addition amount of the first conductive agent 211 in the first layer structure 21 is 0.3%-1.0%, the addition amount of the second conductive agent 231 in the second layer structure 23 is 0.01%-0.3%, and the addition amount of the third conductive agent 221 in the transition layer 22 is 0.03%-0.75%.
[0032] Optionally, the first conductive agent 211 includes a conductive carbon black conductive agent, the second conductive agent 231 includes a graphene conductive agent, and the third conductive agent 221 includes a composite conductive agent formed by a conductive carbon black conductive agent and a carbon nanotube conductive agent; in terms of mass, the ratio of the added amount of the composite conductive agent formed by the conductive carbon black conductive agent and the carbon nanotube conductive agent in the third conductive agent 221 is 1.5-33:1.
[0033] A conductive carbon black conductive agent is added to the first layer structure 21. This type of conductive agent with a point structure can penetrate into the gaps of the first mixture with a larger particle size, and contact the particle structure in the first mixture in a point-to-point manner, thereby ensuring the conductivity of the first layer structure 21; a graphene conductive agent with a planar structure is added to the second layer structure 23. This type of conductive agent has better conductivity, thereby ensuring the conductivity of the second layer structure 23 farthest from the current collector 1; the transition layer 22 adopts a mixed conductive agent system of a carbon nanotube conductive agent with a linear structure and a conductive carbon black with a point structure, thereby ensuring good contact with the third mixture, thereby ensuring the conductivity of the transition layer 22; the conductive carbon black conductive agent with relatively the lowest cost is added to the first layer structure 21, and the graphene conductive agent with relatively the lowest cost is added to the second layer structure 23. The third conductive agent 221 includes a composite conductive agent formed by a conductive carbon black conductive agent and a carbon nanotube conductive agent, thereby achieving cost control of the structure of the electrode active layer 2. The conductive properties of the conductive agent increase layer by layer from near to far and the added amount decreases layer by layer, so that the conductive active layer 2 has both good conductivity and low production cost.
[0034] Optionally, when the lithium-ion battery electrode is a positive electrode, the amount of the adhesive added to the first layer structure 21, the second layer structure 23 and the third layer structure is 1%-2%, 1.5%-2.5% and 1.2%-2.2% respectively, in terms of mass percentage.
[0035] Optionally, when the lithium-ion battery electrode is a negative electrode, the amount of the adhesive added to the first layer structure 21, the second layer structure 23 and the third layer structure is 1.5%-2%, 2.0%-2.5% and 1.8%-2.2% respectively, in terms of mass percentage.
[0036] According to the particle size distribution characteristics of the particles in each layer structure of the electrode active layer 2, the amount of adhesive added in each layer is adjusted to ensure the stability of the electrode active layer 2.
[0037] Optionally, the main material includes one or more of lithium ferrous phosphate, lithium cobalt oxide or lithium manganese oxide, and the adhesive is selected from one or both of polyvinylidene fluoride (PVDF) or styrene-butadiene rubber (SBR).
[0038] Optionally, when the lithium-ion battery electrode is a positive electrode, the current collector 1 includes aluminum foil; when the lithium-ion battery electrode is a negative electrode, the current collector 1 includes copper foil.
[0039] In a second aspect, an embodiment of the present invention provides a method for preparing a lithium-ion battery pole piece, which is used to prepare the lithium-ion battery pole piece as described above, comprising the steps of:
[0040] providing a current collector 1;
[0041] An electrode active layer 2 is coated on the surface of the current collector 1; the electrode active layer 2 includes a first layer structure 21, a transition layer 22 and a second layer structure 23 sequentially coated on the surface of the current collector 1; the electrode active layer 2 includes a main material, a conductive agent and an adhesive, and the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure 21 and the second layer structure 23 respectively, and the transition layer 22 includes a third mixture formed by mixing the first mixture and the second mixture.
[0042] The lithium-ion battery pole piece prepared by the preparation method of the lithium-ion battery pole piece of the present invention includes an electrode active layer 2, and the electrode active layer 2 includes the first structural layer, the transition layer 22 and the second structural layer sequentially formed on the surface of the current collector 1, so as to obtain a thick electrode material with a multi-layer composite layer structure; the first structural layer 21 and the second structural layer are respectively formed by the first mixture and the second mixture of different particle sizes, the particle size of the first mixture is larger than the particle size of the second mixture, and the particle size of the particles in the mixture farther away from the surface of the current collector 1 is smaller. The smaller the particle size of the particles, the better the solid-phase migration of lithium ions. Conversely, the migration of lithium ions with large particles is worse. The first structural layer with larger particle size is arranged close to the current collector 1, which is more It facilitates the gain and loss of electrons, reducing the impedance of the thick electrode; the transition layer 22 includes a third mixture formed by mixing the first mixture and the second mixture, and the particles of large and small sizes are mixed, which reduces the contact impedance of the large and small particles, further reducing the impedance of the thick electrode; in addition, the particle size of the first layer structure 21 in contact with the current collector 1 is larger, so that the surface roughness of the first layer structure 21 is greater, and the bonding force between the first layer structure 21 and the current collector 1 is greater, ensuring the bonding strength between the first layer structure 21 and the current collector 1, and thus ensuring the structural stability of the lithium-ion battery pole piece. The bonding force between the first layer structure 21 and the current collector 1 in the lithium-ion battery pole piece provided by the present invention is greater than 5N / m. Therefore, the preparation method of the lithium-ion battery pole piece of the present invention can prepare a thick electrode material with low impedance, good structural stability and high energy density.
[0043] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0044] The above embodiments merely represent preferred embodiments of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.
Claims
1. A lithium-ion battery pole piece, characterized in that: It includes a current collector and an electrode active layer arranged on the surface of the current collector; wherein, the electrode active layer includes a first layer structure, a transition layer and a second layer structure arranged in sequence on the surface of the current collector; the electrode active layer includes a main material, a conductive agent and an adhesive, and the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure and the second layer structure respectively, and the transition layer includes a third mixture formed by mixing the first mixture and the second mixture.
2. The lithium-ion battery pole piece according to claim 1, characterized in that: The particle size of the first mixture is 5-25 μm, and the particle size of the second mixture is 0.5-5 μm.
3. The lithium-ion battery pole piece according to claim 1, characterized in that: The thickness of a single layer of the first layer structure is 40-95 μm, the thickness of a single layer of the second layer structure is 50-110 μm, and the thickness of a single layer of the transition layer is 40-95 μm.
4. The lithium-ion battery pole piece according to claim 1, characterized in that: The conductive agent includes a first conductive agent, a second conductive agent and a third conductive agent, which are respectively arranged in the first layer structure, the second layer structure and the transition layer; in terms of mass percentage, the amount of the first conductive agent added to the first layer structure is 0.3%-1.0%, the amount of the second conductive agent added to the second layer structure is 0.01%-0.3%, and the amount of the third conductive agent added to the transition layer is 0.03%-0.75%.
5. The lithium-ion battery pole piece according to claim 4, characterized in that: The first conductive agent includes a conductive carbon black conductive agent, the second conductive agent includes a graphene conductive agent, and the third conductive agent includes a composite conductive agent formed by a conductive carbon black conductive agent and a carbon nanotube conductive agent; in terms of mass, the ratio of the composite conductive agent formed by the conductive carbon black conductive agent and the carbon nanotube conductive agent added to the third conductive agent is 1.5-33:
1.
6. The lithium-ion battery pole piece according to claim 1, characterized in that: In terms of mass percentage, when the lithium-ion battery electrode is a positive electrode, the amount of the adhesive added to the first layer structure, the second layer structure and the third layer structure is 1%-2%, 1.5%-2.5% and 1.2%-2.2% respectively.
7. The lithium-ion battery pole piece according to claim 1, characterized in that: In terms of mass percentage, when the lithium-ion battery electrode is a negative electrode, the amount of the adhesive added to the first layer structure, the second layer structure and the third layer structure is 1.5%-2%, 2.0%-2.5% and 1.8%-2.2% respectively.
8. The lithium-ion battery pole piece according to claim 1, characterized in that: The main material includes one or more of lithium ferrous phosphate, lithium cobaltate or lithium manganate, and the adhesive is selected from one or both of polyvinylidene fluoride and styrene-butadiene rubber.
9. The lithium-ion battery pole piece according to claim 1, characterized in that: When the lithium-ion battery electrode is a positive electrode, the current collector includes aluminum foil; when the lithium-ion battery electrode is a negative electrode, the current collector includes copper foil.
10. A method for preparing a lithium-ion battery electrode, characterized in that: The method for preparing a lithium-ion battery electrode according to any one of claims 1 to 9 comprises the following steps: providing a current collector; An electrode active layer is formed by coating the surface of the current collector; the electrode active layer includes a first layer structure, a transition layer and a second layer structure coated in sequence on the surface of the current collector; the electrode active layer includes a main material, a conductive agent and an adhesive, and the main material and the adhesive are mixed to obtain a first mixture and a second mixture, the particle size of the first mixture is larger than the particle size of the second mixture, the first mixture and the second mixture are used to form the first layer structure and the second layer structure respectively, and the transition layer includes a third mixture formed by mixing the first mixture and the second mixture.