Lithium battery cathode plate microstructure
By setting stress relief grooves in the corner area of the lithium battery cathode electrode, the problem of stress concentration at the corner of the wound lithium-ion battery cell is solved, achieving efficient stress relief and high energy density battery performance, and improving the cycle stability and lifespan of the battery.
Patent Information
- Application Number
- CN202512058944.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-31
- Publication Date
- 2026-03-31
Smart Images
Figure CN121768995A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of lithium-ion battery technology, specifically to a microstructure of a lithium battery cathode electrode. Background Technology
[0002] With the rapid development of electric vehicles, portable electronic devices, and energy storage power stations, increasingly higher demands are being placed on the energy density, cycle life, and safety performance of lithium-ion batteries. Silicon (Si)-based materials, especially silicon-carbon (Si / C) composites, are considered a key choice for next-generation high-energy-density lithium-ion battery anode materials due to their extremely high theoretical specific capacity.
[0003] However, silicon materials exhibit significant volume expansion during charging and discharging. This repeated and substantial expansion and contraction generates enormous mechanical stress, leading to the pulverization of active material particles, repeated rupture and regeneration of the solid electrolyte interfacial film, and electrode structure collapse. Ultimately, this results in electrode-current collector separation, active material failure, and rapid capacity decay. This is one of the core bottlenecks restricting the commercial application of silicon-based anodes.
[0004] In wound or stacked lithium-ion batteries using silicon-carbon anodes, in addition to the expansion stress of the materials themselves, the physical structure of the core introduces additional areas of mechanical stress concentration. Particularly at the corners of wound cells, the electrodes are subjected to complex bending stresses and interlayer compression. When using high-expansion silicon-carbon anodes, the stress concentration at these corners is amplified dramatically, making the cathode and / or anode electrode coatings highly susceptible to microcracks. With increasing cycle count, these cracks propagate and connect, eventually leading to the fracture of the electrode coating and even the breakage of the current collector. Once the electrode breaks at a corner, the internal conductive path is interrupted, some active materials become deactivated, the battery's internal resistance rises sharply, and the capacity drops drastically—the so-called cycle-drop phenomenon.
[0005] To address the aforementioned issues, several solutions have been proposed in existing technologies. One common method is to attach reinforcing tape to the corners or easily breakable areas of the electrode. By adding a layer of tape to the electrode surface, local reinforcement and crack propagation can be achieved. However, this method has significant drawbacks: First, the introduction of tape increases additional material and processing costs; second, the tape itself occupies a certain volume and weight, reducing the overall energy density of the battery; third, the adhesive performance of the tape may degrade under long-term cycling and electrolyte immersion environments, affecting long-term reliability; finally, the tape application process requires high precision, increasing production complexity.
[0006] Another approach is to improve the flexibility or mechanical strength of the electrode by optimizing the electrode slurry formulation or coating structure, for example, by introducing reinforcing phases such as elastic binders or carbon nanotubes. While these methods can improve the overall mechanical properties of the electrode at the material level, they often come at the cost of sacrificing some electrochemical performance or increasing costs, and their effectiveness in alleviating the unique geometric stress concentration at corners is limited.
[0007] Therefore, how to propose a microstructure for lithium battery cathode electrodes that can effectively alleviate or release concentrated stress in the corner area of the wound cell has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0008] To address at least one of the technical problems in the background art, the present invention provides a microstructure for a lithium battery cathode electrode, which can effectively alleviate or release the concentrated stress in the corner area of the wound cell without significantly increasing the battery volume and weight or introducing additional heterogeneous materials. This fundamentally suppresses the risk of electrode breakage during cycling, thereby significantly improving the cycle stability and lifespan of lithium-ion batteries using high-expansion negative electrode materials such as silicon-carbon.
[0009] To achieve the above objectives, the present invention provides a microstructure of a lithium battery cathode electrode, comprising: a current collector and an active material coating coated on at least one surface of the current collector; when the cathode electrode is used to wind and form a battery cell, at least one stress relief groove group distributed along the length direction of the electrode is provided on the coating corresponding to the corner area of the battery cell. Each of the stress-relieving groove groups includes at least one groove unit, which is a groove formed by physically removing the active material coating in that area.
[0010] Furthermore, the structural parameters of the groove unit in the stress relief groove group are adaptively designed according to the distance of its position from the starting interface of the battery cell winding.
[0011] Furthermore, for the same layer of electrode sheet of the wound cell, the stress relief groove group is symmetrically arranged in the left and right corner areas.
[0012] Furthermore, the shape of the groove unit is horizontal, vertical, diagonal, or any combination thereof.
[0013] Furthermore, the structural parameters of the groove unit include depth and / or number; as the distance between the location of the groove group and the winding start interface increases, the depth of the groove unit increases and / or the number of groove units increases.
[0014] Furthermore, the formula for calculating the depth of the nth groove element is as follows: S = (Dn / L) 0.9H) Where S is the depth of the groove unit, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and H is the thickness of the single-sided electrode.
[0015] Furthermore, the formula for calculating the number of groove units in the nth groove region is as follows: Z = (Dn / L) W) Where Z is the number of groove units, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and W is the cell length.
[0016] The beneficial effects of this invention are as follows: (1) High-efficiency stress release: By prefabricating a controllable groove structure in the stress concentration area at the corner, the composite stress generated by the expansion and winding of the silicon-carbon negative electrode is actively guided and released, avoiding the disorderly accumulation and concentrated outbreak of stress, fundamentally inhibiting the initiation and expansion of coating cracks, and preventing electrode breakage.
[0017] (2) Maintaining high energy density: This invention achieves stress relief by reducing the active material in localized areas, rather than by adding external materials. The reduced mass of active material is negligible compared to the overall functionality of the active material retained to prevent breakage, and does not increase any additional volume. Therefore, compared to adhesive bonding solutions, this invention maintains a higher active material loading in the same volume, thereby maintaining the high energy density of the battery.
[0018] (3) Good process compatibility: The groove forming process is easy to integrate into the existing electrode production line, which can realize high-precision and high-efficiency online processing without significantly increasing production costs.
[0019] (4) Scientific and flexible design: The proposed gradient design formula provides universal design guidance for cells of different sizes and different winding turns, so that the stress relief structure matches the actual stress state of the cell and the optimization effect is significant.
[0020] (5) Improved cycle life: The lithium battery using the present invention, especially the lithium battery using silicon-carbon negative electrode, has significantly improved cycle life, especially the anti-fracture ability of the electrode at the corner, which effectively alleviates the problem of cycle drop in high energy density batteries and improves the reliability and service life of the battery. Attached Figure Description
[0021] Figure 1 This is a schematic diagram of the microstructure of the lithium battery cathode electrode of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the microstructure of the lithium battery cathode electrode of the present invention. Figure 2 ; Figure 3This is a schematic diagram of the microstructure of the lithium battery cathode electrode of the present invention. Figure 3 ; Figure 4 This is a dimensional diagram of the microstructure of the lithium battery cathode electrode of the present invention. Detailed Implementation
[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0023] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0024] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.
[0025] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0026] Furthermore, the terms "installation," "setup," "equipped with," "connection," "linking," and "socketing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral structure; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.
[0027] To achieve the above objectives, such as Figures 1 to 3 As shown, the present invention provides a microstructure of a lithium battery cathode electrode, comprising: a current collector and an active material coating coated on at least one surface of the current collector; when the cathode electrode is used to wind and form a battery cell, at least one stress relief groove group distributed along the length direction of the electrode is provided on the coating corresponding to the corner area of the battery cell. Each of the stress-relieving groove groups includes at least one groove unit, which is a groove formed by physically removing the active material coating in that area.
[0028] This invention improves the cycle performance of batteries by precisely controlling the microstructure of the electrode coating in a specific area in situ and introducing a stress-relieving groove group, which effectively disperses and releases the concentrated stress in the corner area, thereby significantly improving the cycle performance of batteries without adding extra materials or reducing energy density.
[0029] To further optimize the technical solution, the structural parameters of the groove unit in the stress relief groove group are adaptively designed according to the distance of its position from the starting interface of the battery cell winding.
[0030] To further optimize the technical solution, for the same layer of electrode sheet of the wound cell, the stress relief groove group is symmetrically set in the left and right corner areas.
[0031] To further optimize the technical solution, the groove unit is shaped like a horizontal line (e.g., Figure 1 As shown), vertical lines (such as...) Figure 3 As shown), diagonal lines (such as...) Figure 2 (as shown) or any combination thereof.
[0032] To further optimize the technical solution, the structural parameters of the groove unit include depth and / or quantity; as the distance between the location of the groove group and the winding start interface increases, the depth of the groove unit increases and / or the quantity increases.
[0033] Further optimize the technical solution, refer to Figure 4 The formula for calculating the depth of the nth groove unit is as follows: S = (Dn / L) 0.9H) Where S is the depth of the groove unit, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and H is the thickness of the single-sided electrode.
[0034] Further optimize the technical solution, refer to Figure 4 The formula for calculating the number of groove units in the nth groove region is as follows: Z = (Dn / L) W) Where Z is the number of groove units, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and W is the cell length.
[0035] Through the above design, the corner areas located on the outer edge of the cell, which bear greater bending and compressive stress, have deeper or more groove units, thus providing stronger stress relief capabilities; while the inner ring areas have shallower or fewer groove units, ensuring a certain level of stress relief while minimizing the loss of active material loading. This gradient and adaptive design achieves an optimal balance between stress relief effect and energy density maintenance.
[0036] The method for preparing a lithium battery cathode electrode provided by the present invention includes the following steps: S1 provides the current collector; S2, mixing cathode active material, conductive agent, binder and solvent to prepare cathode slurry; S3, the cathode slurry is coated onto the current collector and dried to form an active material coating with a predetermined thickness; S4, using precision physical processing methods, the stress relief groove group is formed on the coating corresponding to the corner area of the future battery cell; The preferred processing methods are non-contact laser etching or contact precision doctor blade / imprint roller technology. Laser etching offers advantages such as high precision, no mechanical stress, and flexible pattern adjustment. Doctor blade or imprint roller technology is suitable for large-scale continuous production. It can be performed after coating drying and before rolling, or after rolling. Performing it after rolling allows for more precise control of the groove depth of the final electrode sheet.
[0037] S5, after the electrode sheet with stress relief grooves is formed, roll pressing and slitting are performed to obtain the finished cathode electrode sheet.
[0038] The present invention also provides a lithium battery, including a casing, an electrolyte, and a cell disposed within the casing. The cell includes an anode electrode, a separator, and the aforementioned cathode electrode.
[0039] This invention utilizes a pre-fabricated, controllable groove structure in the stress concentration area at corners to actively guide and release the combined stress generated by the expansion and bending of the silicon-carbon negative electrode. This avoids the disordered accumulation and concentrated burst of stress, fundamentally suppressing the initiation and propagation of coating cracks and preventing electrode breakage. This invention achieves stress release by reducing the active material in localized areas, rather than adding external materials. The reduced mass of active material is negligible compared to the overall functionality of the active material retained to prevent breakage, and it does not increase any additional volume. Therefore, compared to adhesive bonding solutions, this invention maintains a higher active material loading in the same volume, thus maintaining the battery's high energy density. The groove forming process is easily integrated into existing electrode production lines, enabling high-precision, high-efficiency online processing without significantly increasing production costs. The proposed gradient design formula provides universal design guidance for cells of different sizes and winding turns, matching the stress release structure with the actual stress state of the cell, resulting in significant optimization. The lithium batteries using this invention, especially those employing silicon-carbon anodes, exhibit significantly enhanced cycle life, particularly the resistance to breakage of the electrode plates at corners. This effectively alleviates the cycle life degradation problem of high-energy-density batteries and improves battery reliability and lifespan.
[0040] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A microstructure for a lithium battery cathode electrode, characterized in that, include: A current collector and an active material coating applied to at least one surface of the current collector; When the cathode electrode is used to wind and form a battery cell, at least one stress relief groove group is provided on the coating corresponding to the corner area of the battery cell, which is distributed along the length direction of the electrode. Each of the stress-relieving groove groups includes at least one groove unit, which is a groove formed by physically removing the active material coating in that area.
2. The lithium battery cathode electrode microstructure as described in claim 1, characterized in that, The structural parameters of the groove unit in the stress relief groove group are adaptively designed according to the distance of its position from the starting interface of the battery cell winding.
3. The microstructure of a lithium battery cathode electrode as described in claim 1, characterized in that, For the same layer of electrode sheet of the wound cell, the stress relief groove group is symmetrically arranged in the left and right corner areas.
4. A microstructure for a lithium battery cathode electrode as described in claim 1 or 2, characterized in that, The groove unit can be horizontal, vertical, diagonal, or any combination thereof.
5. A microstructure for a lithium battery cathode electrode as described in claim 4, characterized in that, The structural parameters of the groove unit include depth and / or number; as the distance between the location of the groove group and the winding start interface increases, the depth of the groove unit increases and / or the number of groove units increases.
6. A microstructure for a lithium battery cathode electrode as described in claim 5, characterized in that, The formula for calculating the depth of the nth groove element is as follows: S=(Dn / L 0.9H) Where S is the depth of the groove unit, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and H is the thickness of the single-sided electrode.
7. A microstructure for a lithium battery cathode electrode as described in claim 5 or 6, characterized in that, The formula for calculating the number of groove units in the nth groove region is as follows: Z=(Dn / L W) Where Z is the number of groove units, Dn is the distance from the middle part of the nth groove region to the membrane foil interface, L is the total electrode length, and W is the cell length.