Pole piece
By introducing a safety coating of nano-organic particles, nano-inorganic particles, and polar binders into the electrode, the problems of excessive safety coating thickness and insufficient bonding strength are solved, thereby improving the cell capacity and enhancing structural stability.
Patent Information
- Application Number
- CN202423212150.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-25
- Publication Date
- 2026-02-13
- Estimated Expiration
- 2034-12-25
AI Technical Summary
The excessive thickness of the safety coating on the existing electrode leads to a decrease in the cell's capacity, insufficient bonding strength between the current collector and the safety coating, and an unstable cell structure.
A safety coating composed of nano-organic particles and nano-inorganic particles and a polar binder is used to control its aspect ratio to be greater than 10, reduce the thickness of the safety coating to less than 1 μm, and enhance the bonding strength between the current collector and the safety coating.
It improves the capacitance and structural stability of the battery cell, ensures good structural strength of the safety coating even at a thin thickness, and enhances the adhesion strength between the current collector and the safety coating.
Smart Images
Figure CN223911633U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to lithium battery technical field especially relates to a pole piece. BACKGROUND
[0002] The electric core is the core in lithium ion battery, and the electric core is composed of positive pole piece, negative pole piece, diaphragm, pole lug and electrolyte, the pole piece is very important in the electric core, and the existing pole piece is mainly composed of current collector and active material layer at present, in order to avoid that lithium battery is easy to fire or explode under the condition of collision, extrusion etc., therefore, generally, safety coating is arranged in the pole piece, in order to guarantee the structural strength of safety coating, the thickness of the existing safety coating is too thick, can cause the thickness reduction of active material layer, makes the electric capacity of electric core drop. In addition, in the prior art, the adhesive strength between the current collector and the safety coating is not enough, and the structure between the current collector and the safety coating is not stable when the electric core is subjected to collision and extrusion. SUMMARY
[0003] The utility model discloses a kind of pole pieces, the thickness of safety coating is reduced, the electric capacity of electric core is improved;In addition, the adhesive strength between current collector and safety coating is improved, and the stability of electric core structure is improved.
[0004] In order to achieve the above object, the utility model provides a kind of pole piece, including current collector, two layers of active material layer, two layers of safety coating, the two sides of the current collector are equipped with a layer of safety coating, the side of safety coating away from the current collector is equipped with the active material layer, the safety coating is equipped with nano organic particle, nano inorganic particle and polar adhesive, the length-diameter ratio of the nano organic particle, the length-diameter ratio of the nano inorganic particle are all greater than 10, and the thickness of the safety coating is less than 1um.
[0005] Further, the current collector is aluminum foil, and the thickness of the aluminum foil is 4um-14um.
[0006] Further, the current collector is copper foil, and the thickness of the copper foil is 4-12um.
[0007] Further, the diameter of the nano organic particle is between 1nm-100nm.
[0008] Further, the diameter of the nano inorganic particle is between 1nm-200nm.
[0009] Further, the thickness of the active material layer is between 20um-40um.
[0010] Further, the nano inorganic particle includes at least one of single-walled carbon nanotube or multi-walled carbon nanotube. Further, the nano inorganic particle includes at least one of single-walled carbon nanotube or multi-walled carbon nanotube.
[0011] Further, the nano-organic particles are cellulose.
[0012] The pole piece has the advantages that the safety coating comprises nano-organic particles, nano-inorganic particles and a polar binder, the aspect ratio of the nano-organic particles and the aspect ratio of the nano-inorganic particles are greater than 10, the aspect ratio of the nano-organic particles and the nano-inorganic particles is controlled, the acting force between the nano-inorganic particles and the nano-organic particles is improved, the safety coating has good structural strength when the thickness of the safety coating is less than 1 um, the thickness of the safety coating can be reduced, and the capacitance of the battery cell is improved. BRIEF DESCRIPTION OF DRAWINGS
[0013] Figure 1 is a structural schematic view of a pole piece of the utility model embodiment;
[0014] Figure 2 is a structural schematic view of a safety coating of the pole piece of the utility model embodiment.
[0015] In the figure, 1, current collector; 2, active material layer; 3, safety coating; 31, nano-organic particle; 32, nano-inorganic particle; 33, polar binder. DETAILED DESCRIPTION
[0016] The specific implementation of the utility model will be described in further detail below in combination with the drawings and embodiments. The following embodiments are used to illustrate the utility model, but not to limit the scope of the utility model.
[0017] In the description of the utility model, it should be understood that the positions or location relations indicated by the terms "upper", "lower", "front", "rear", "inner", "outer" and the like in the utility model are based on the position relations shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices and elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the utility model.
[0018] As shown in Figure 1 , Figure 2 The utility model preferred embodiment's a pole piece, including current collector 1, two layers of active material layer 2, two layers of safety coating 3, wherein, refer to Figure 1It can be known that the safety coating 3 is arranged on both sides of the current collector 1, and the active material layer 2 is arranged on the side of the safety coating 3 away from the current collector 1. In order to reduce the thickness of the safety coating 3 and ensure the thickness of the active material layer 2, the nanometer organic particles 31, the nanometer inorganic particles 32 and the polar binder 33 are arranged in the safety coating 3. The length-diameter ratio of the nanometer organic particles 31 and the length-diameter ratio of the nanometer inorganic particles 32 are greater than 10, and the two kinds of nanometer particles and the polar binder 33 are uniformly dispersed in the safety coating 3. By controlling the length-diameter ratio of the nanometer organic particles 31 and the nanometer inorganic particles 32, the interaction between the nanometer inorganic particles 32 and the nanometer organic particles 31 is improved, and the thickness of the safety coating 3 is less than 1 um, and the safety coating 3 still has good structural strength. In addition, the polar binder 33 is arranged in the safety coating 3, the bonding strength between the current collector 1 and the safety coating 3 is increased, and the stability of the battery structure is improved.
[0019] In some embodiments, the above-mentioned tab can be used for a positive tab or a negative tab. In the positive tab or the negative tab, the current collector 1 can be made of an aluminum foil or a copper foil. In order to facilitate the control of the thickness of the current collector 1, specifically, when the current collector 1 is made of an aluminum foil, the thickness of the aluminum foil is 4 um-14 um, and preferably, the thickness of the aluminum foil can be 9 um. When the current collector 1 is a copper foil, the thickness of the copper foil is 4-12 um, and preferably, the thickness of the copper foil can be 8 um. The material and thickness of the current collector 1 can be designed according to actual production needs. At the same time, the thickness of the active material layer 2 is between 20 um and 40 um, and can be adaptively adjusted according to the actual capacity of the battery. In the preferred embodiment, the thickness of the active material layer 2 can be set to 30 um.
[0020] In some embodiments, in order to facilitate the control of the length-diameter ratio of the nanometer organic particles 31, the length of the nanometer organic particles 31 is between 10 nm and 10000 nm, and the diameter of the nanometer organic particles 31 is between 1 nm and 100 nm. By controlling the length and diameter of the nanometer organic particles 31, the length-diameter ratio of the nanometer organic particles 31 is greater than 10.
[0021] Similarly, in some embodiments, in order to facilitate the control of the length-diameter ratio of the nanometer inorganic particles 32, the length of the nanometer inorganic particles 32 is greater than 1 um, and the diameter of the nanometer inorganic particles 32 is between 1 nm and 200 nm, so that the length-diameter ratio of the nanometer inorganic particles 32 is greater than 10. Specifically, in the embodiment, the nanometer inorganic particles 32 include at least one of a single-walled carbon nanotube or a multi-walled carbon nanotube, which functions to enhance the conductivity of the battery safety coating 3. At the same time, the carbon nanotube with such a length-diameter ratio performs well in mechanical properties, has high strength and toughness, and the longer carbon nanotube is more likely to form a network structure in the matrix, thereby improving the buffering performance.
[0022] In some embodiments, the nano-organic particles 31 are cellulose, and the greater the aspect ratio of the cellulose, the more effectively the tensile strength and bending stiffness of the fiber can be improved. This makes the safety coating 3 more stable when subjected to external forces and less likely to break or deform. In some other embodiments, the nano-organic particles 31 can be nano-chitosan.
[0023] Specifically, in some embodiments, the polar binder 33 can be an acrylic binder or a modified binder containing polar groups (containing polar groups such as hydroxyl or carbonyl groups), which can be selected according to actual production needs.
[0024] Further, in order to facilitate the testing of the adhesion performance and the capacitance of the prepared electrode sheet, in the present embodiment, dry adhesion and wet adhesion tests are performed on the negative electrode sheet after the simulated cell is rolled. Specifically, the prepared negative electrode sheet is subjected to dry adhesion (room temperature test), wet adhesion (simulated cell process parameters, 24h of electrolyte immersion at room temperature, 24h of electrolyte immersion at 45°C) test, wherein the test method for dry adhesion is as follows: the sample electrode sheet is cut into a strip of a specified size, the strip-shaped sample is peeled off with a universal tensile testing machine, and the force value data at the time of separation is recorded.
[0025] The test method for wet adhesion is as follows: the electrode sheet is placed in the configured electrolyte at room temperature for 24h, then the electrode sheet after standing is placed in the configured electrolyte at 45°C for 24h, the sample electrode sheet is cut into a strip of a specified size, the strip-shaped sample is peeled off with a universal tensile testing machine, and the force value data at the time of separation is recorded.
[0026] The test method for capacitance is as follows: at 25°C, the lithium ion battery is charged at 1C constant current to 3.0V, 3.2V and 3.4V, then charged at 3.0V, 3.2V and 3.4V constant voltage to a current less than 0.05C, then the lithium ion battery is discharged at 1C constant current to 3.0V, 3.2V and 3.4V, which is one charge and discharge process. Repeat the charging and discharging, and calculate the capacity retention rate after 800 cycles of the lithium ion battery.
[0027] In summary, the electrode sheet provided in the present embodiment has the following advantages compared with the prior art: the safety coating 3 includes nano-organic particles 31, nano-inorganic particles 32 and a polar binder, the aspect ratio of the nano-organic particles 31 and the aspect ratio of the nano-inorganic particles 32 are both greater than 10, by controlling the aspect ratio of the nano-organic particles 31 and the nano-inorganic particles 32, the interaction between the nano-inorganic particles 32 and the nano-organic particles 31 is improved, so that when the thickness of the safety coating 3 is less than 1um, the safety coating 3 still has good structural strength, the thickness of the safety coating 3 can be reduced, and the capacitance of the cell is improved. At the same time, the use of a polar binder increases the adhesion strength between the current collector 1 and the safety coating 3, and improves the stability of the cell structure.
[0028] The above merely describes preferred embodiments of the present application, and it should be noted that, for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and replacements can be made, and these improvements and replacements should also be considered as the protection scope of the present application.
Claims
1. A pole piece characterized by: The safety coating layer is provided with nano organic particles, nano inorganic particles and a polar binder, the length-diameter ratio of the nano organic particles and the length-diameter ratio of the nano inorganic particles are greater than 10, and the thickness of the safety coating layer is less than 1 um.
2. The pole piece of claim 1, wherein: The thickness of the aluminum foil is 4 um-14 um.
3. The pole piece of claim 1, wherein: The thickness of the copper foil is 4-12 um.
4. The pole piece of claim 1, wherein: The diameter of the nano organic particles is between 1 nm-100 nm.
5. The pole piece of claim 1, wherein: The diameter of the nano inorganic particles is between 1 nm-200 nm.
6. The pole piece of claim 1, wherein: The thickness of the active material layer is between 20 um-40 um.
7. The pole piece of claim 1, wherein: The nano inorganic particles include at least one of single-walled carbon nanotubes or multi-walled carbon nanotubes.
8. The pole piece of claim 1, wherein: The nano organic particles are cellulose.