A negative electrode structure, a method for manufacturing the same, and a battery

Abstract

This invention provides a negative electrode structure, its fabrication method, and a battery. The negative electrode structure includes two composite current collector layers and an electroplated mesh layer sandwiched between the two composite current collector layers. The surface of the composite current collector layers is covered with through holes. Each composite current collector layer includes a current collector and an anti-electroplating layer disposed on one side of the current collector. All anti-electroplating layers in the composite current collector layer are disposed on the side of the current collector away from the electroplated mesh layer. At least one anti-electroplating mesh layer is disposed between the current collector and the electroplated mesh layer. This invention simplifies the electrode fabrication process and improves the electrode capacity by adding an anti-electroplating mesh layer between the electroplated mesh layer and the current collector.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, and relates to a negative electrode structure, its preparation method, and a battery. Background Technology

[0002] Secondary batteries are not only used as energy storage media in mobile devices, but recently they have also been widely used in medium and large-scale fields such as electric vehicles and power storage. The main components of a secondary battery can be divided into positive electrode, negative electrode, separator, and electrolyte. For commonly used lithium secondary batteries, the components include oxide positive electrode materials, graphite negative electrode materials, polymer separators, and liquid electrolytes. The positive and negative electrodes are prepared by using aluminum and copper foil as current collectors and coating the corresponding active materials on the surface of the current collectors.

[0003] For lithium-ion batteries, during charging, lithium ions at the positive electrode move to the negative electrode through the electrolyte, while electrons move to the negative electrode through an external circuit. Lithium ions are reduced in the negative electrode, and the reduced lithium is stored in the active material of the negative electrode. During this process, energy is stored in the battery. During discharging, lithium ions and electrons move back from the negative electrode to the positive electrode, at which point the energy stored during charging is used.

[0004] Among methods of charging lithium to the negative electrode, lithium metal plating is the simplest and also advantageous in terms of energy density. However, for this type of lithium metal negative electrode, during the process of moving from the plated lithium to the positive electrode—that is, during the charging and discharging process of the battery—repeatedly undergoes changes in electrode volume due to lithium plating and desorption, which may lead to deformation of the battery shape and affect battery life. Furthermore, due to uneven current distribution, dendritic lithium plating occurs. These dendritic lithium dendrite structures continue to grow and expand, eventually piercing the separator and causing a short circuit, resulting in safety issues such as battery overheating and fire.

[0005] Therefore, how to provide a negative electrode structure that can ensure the electroplating and desorption of metal ions in the negative electrode, and has the characteristics of simple structure and easy processing and preparation, has become an urgent technical problem to be solved. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a negative electrode structure, its preparation method, and a battery. By setting an electroplated mesh layer with a grid structure between the current collectors, the electroplated mesh layer provides electroplating space for metal ions in the battery. Furthermore, an anti-electroplation mesh layer is set between the current collector and the electroplated mesh layer to optimize the electroplating space. This can prevent the growth of metal dendritic structures generated by electroplating through the through-holes of the current collector, which could cause short circuits due to puncturing the separator. The invention features a simple preparation process, high flexibility, and low cost.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a negative electrode structure, the negative electrode structure comprising two composite current collector layers and an electroplated mesh layer sandwiched between the two composite current collector layers, wherein the surface of the composite current collector layers is covered with through holes; the composite current collector layer comprises a current collector and an anti-electroplating layer disposed on one side surface of the current collector, wherein the anti-electroplating layers in the composite current collector layer are all disposed on the side surface of the current collector away from the electroplated mesh layer, and at least one anti-electroplating mesh layer is disposed between the current collector and the electroplated mesh layer.

[0009] In this invention, an electroplated mesh layer is set between the current collectors to provide space for the electroplating and desorption of metal ions in the battery. Furthermore, an anti-electroplation mesh layer is added between the current collectors and the electroplated mesh layer. This not only optimizes the electroplating space for metal ions and prevents the formed metal dendritic structure from penetrating through the through-holes of the current collector, thus avoiding the risk of short circuit, but also allows the distance between the current collectors to be adjusted by utilizing the thickness of the anti-electroplation mesh layer, thereby controlling the size of the electroplating space for metal ions and improving the capacity performance of the electrode. This invention has the advantages of simple manufacturing process, high flexibility and low cost.

[0010] For negative electrode structures without an anti-plating mesh layer, when the mesh lines in the plating mesh layer intersect with the through-holes of the current collector, the metal grown on the plating lines can easily penetrate through the through-holes of the current collector, posing a risk of puncturing the separator. If the mesh holes in the plating mesh layer are aligned and coincident with the through-holes of the current collector, the metal plating growth is confined within the plating mesh layer, thus avoiding the above problem. However, the alignment process is complex, and it is difficult to ensure that each through-hole and mesh hole are aligned and coincident. In addition, to increase the distance between current collectors to improve capacity performance, the above structure can increase the thickness of the plating mesh layer by increasing the diameter of the mesh lines, but this will result in smaller mesh holes, so the effect of increasing internal space is not obvious. Although the specifications of the mesh lines and mesh holes can be matched to find a more suitable size, the matching of the through-hole size in the current collector and the mesh size of the plating mesh layer still has extremely high requirements. In this invention, by adding an anti-plating mesh layer between the current collector and the electroplating mesh layer, it is not necessary to ensure that the through holes of the current collector and the mesh holes of the electroplating mesh layer are aligned and coincident during the preparation of the negative electrode structure. The anti-plating mesh layer achieves the function of restricting the growth of metal electroplating, optimizing the space for metal electroplating growth. Moreover, for increasing the electrode capacity by increasing the distance between current collectors, this invention only needs to change the thickness of the anti-plating mesh layer, which can be adjusted through a multi-layer structure. Furthermore, through the design of the anti-plating mesh layer structure, this invention can use different through hole sizes and electroplating mesh layer sizes, effectively reducing production costs.

[0011] It should be noted that, in this invention, the electroplating mesh layer represents a mesh layer capable of enhancing the electroplating of metal ions in the induced cell. For example, the metal ions can be lithium, sodium, zinc, or magnesium, which are metal anodes capable of being electroplated in a metallic state. Therefore, the anti-electroplating mesh layer in this invention represents a mesh layer capable of preventing the electroplating of metal ions, meaning that metal ions will not be electroplated on the anti-electroplating mesh layer.

[0012] It should be noted that in this invention, the through holes in the composite current collector layer penetrate both the current collector and the anti-electroplating layer.

[0013] It should be noted that the present invention does not impose specific requirements or special limitations on the material of the current collector. Those skilled in the art can reasonably select the material of the current collector according to the type of battery, for example, it can be copper foil.

[0014] It should be noted that the arrangement of the through holes in this invention can be a matrix arrangement or an alternating arrangement.

[0015] As a preferred embodiment of the present invention, the material of the anti-electroplating mesh layer includes an electroplating inhibition material.

[0016] It should be noted that the electroplating inhibition material in this invention refers to a material that can inhibit the electroplating of metal ions in the battery, that is, the metal ions do not electroplating on the surface of the electroplating inhibition material, thereby preventing electroplating growth on the anti-electroplating mesh layer. Furthermore, those skilled in the art can rationally select the electroplating inhibition material according to the different types of electroplating metal ions in the battery.

[0017] Preferably, the electroplating inhibition material includes one or a combination of at least two of nylon, polyethylene, polypropylene, polyvinyl alcohol, or polyvinyl chloride.

[0018] As a preferred embodiment of the present invention, the mesh size of the anti-electroplating mesh layer is 10 to 500 mesh, for example, 10 mesh, 50 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh or 500 mesh, and more preferably 30 to 200 mesh.

[0019] Preferably, the thickness of the anti-electroplated mesh layer is 10 to 20 μm, for example, 10 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0020] As a preferred embodiment of the present invention, the thickness of the current collector is 5 to 10 μm, for example, 5.0 μm, 5.5 μm, 6.0 μm, 6.5 μm, 7.0 μm, 7.5 μm, 8.0 μm, 8.5 μm, 9.0 μm, 9.5 μm or 10.0 μm.

[0021] Preferably, the diameter of the through hole is 500 to 2000 μm, for example, 500 μm, 600 μm, 800 μm, 1000 μm, 1200 μm, 1400 μm, 1600 μm, 1800 μm or 2000 μm.

[0022] Preferably, the spacing between the through holes is 250 to 1000 μm, for example, 250 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm or 1000 μm.

[0023] As a preferred embodiment of the present invention, the thickness of the anti-electroplating layer is 10-20 μm, for example, 10 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0024] Preferably, the material of the anti-electroplating layer includes an electroplating inhibiting material.

[0025] As a preferred embodiment of the present invention, the mesh size of the electroplated mesh layer is 10 to 500 meshes, for example, 10 mesh, 50 mesh, 100 mesh, 150 mesh, 200 mesh, 250 mesh, 300 mesh, 350 mesh, 400 mesh, 450 mesh, or 500 mesh. Optionally, the size of the electroplated mesh layer is the same as the size of the anti-electroplated mesh layer.

[0026] Preferably, the thickness of the electroplated mesh layer is 10 to 20 μm, for example, 10 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm or 20 μm.

[0027] As a preferred embodiment of the present invention, the material of the electroplating mesh layer includes an electroplating induction material.

[0028] It should be noted that, in this invention, the electroplating induction material refers to a material that can induce the electroplating growth of metal ions in the battery. That is, metal ions can be electroplated and grown on the surface of the electroplating induction material. Furthermore, those skilled in the art can reasonably select the electroplating induction material according to the different metal ions in the battery, thereby ensuring the electroplating effect of the metal ions. For example, if the metal ion is lithium ion, then the electroplating induction material can be zinc oxide.

[0029] Preferably, the electroplating induction material includes zinc oxide.

[0030] It should be noted that the present invention does not impose specific requirements or special limitations on the structure of the electroplated mesh layer. Those skilled in the art can make reasonable choices according to actual needs. For example, the electroplated mesh layer can be a mesh layer structure made directly from an electroplating inducing material, or it can be a mesh layer structure prepared from a substrate material, and then an electroplating inducing material is further coated on the surface of the substrate material to form an electroplated mesh layer with an electroplating inducing material on the surface.

[0031] It should be noted that the present invention does not impose specific requirements or special limitations on the structure of the anti-electroplating mesh layer. Those skilled in the art can make reasonable choices according to actual needs. For example, the anti-electroplating mesh layer can be a mesh layer structure made directly from a material that is constantly being electroplated, or it can be a mesh layer structure made from a base material and an electroplating inhibition material coated on the base material to form an electroplating mesh layer with an electroplating inhibition material on the surface.

[0032] In a second aspect, the present invention provides a method for preparing a negative electrode structure as described in the first aspect, the method comprising:

[0033] Two composite current collector layers with through holes are prepared. The composite current collector layer includes a current collector and an anti-electroplating layer stacked together. An electroplating mesh layer is set between the composite current collector layers. The current collector side of the composite current collector layer is close to the electroplating mesh layer. At least one anti-electroplating mesh layer is set between the current collector and the electroplating mesh layer to prepare the negative electrode structure.

[0034] The negative electrode structure preparation method provided by this invention eliminates the need to align the through holes of the current collector with the mesh holes of the electroplating mesh layer during the preparation process, simplifying the preparation steps of the negative electrode structure. Furthermore, by adjusting the number and thickness of the anti-electroplating mesh layer, the distance between the current collectors can be adjusted, thereby optimizing the electroplating space and improving the capacity performance of the negative electrode.

[0035] For example, a method for preparing the above-mentioned electroplated mesh layer is provided, which specifically includes: preparing a mesh layer structure from a substrate material, such as a nylon mesh structure, coating an electroplating inducing substance on the mesh layer structure to form an electroplated mesh layer.

[0036] As a preferred technical solution of the present invention, the preparation method of the composite current collector layer includes: after forming a through hole on the surface of the current collector, forming an anti-electroplating layer on one side of the current collector, or after forming an anti-electroplating layer on the surface of the current collector, forming a through hole on the surface of the current collector with the anti-electroplating layer.

[0037] Preferably, the anti-electroplating layer is applied by means of coating.

[0038] For example, a method for preparing a composite current collector layer is provided, comprising: firstly, forming a through hole in a current collector; after forming the through hole, coating an anti-electroplating layer onto the surface of the current collector to form a composite current collector layer with a through hole structure; or, after coating an anti-electroplating layer on the current collector, forming a through hole in the current collector with the anti-electroplating layer to form a composite current collector layer with a through hole structure.

[0039] Thirdly, the present invention provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode adopts the negative electrode structure described in the first aspect.

[0040] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] In this invention, an electroplated mesh layer is set between the current collectors to provide space for the electroplating and desorption of metal ions in the battery. Furthermore, an anti-electroplation mesh layer is added between the current collectors and the electroplated mesh layer. This not only optimizes the electroplating space for metal ions and prevents the formed metal dendritic structure from penetrating through the through-holes of the current collector, thus avoiding the risk of short circuit, but also allows the distance between the current collectors to be adjusted by utilizing the thickness of the anti-electroplation mesh layer, thereby controlling the size of the electroplating space for metal ions and improving the capacity performance of the electrode. This invention has the advantages of simple manufacturing process, high flexibility and low cost. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the negative electrode structure provided in Embodiment 1 of the present invention;

[0044] Figure 2 This is a schematic diagram of the negative electrode structure provided in Comparative Example 1 of the present invention;

[0045] Figure 3 This is a diagram showing the electroplated metal growth of the negative electrode structure provided in Embodiment 1 of the present invention;

[0046] Figure 4 This is a diagram showing the electroplated metal growth of the negative electrode structure provided in Comparative Example 1 of the present invention;

[0047] Figure 5 This is a disassembled diagram of the negative electrode structure in Embodiment 1 of the present invention;

[0048] Figure 6 This is a disassembled diagram of the negative electrode structure in Embodiment 2 of the present invention;

[0049] Figure 7This is a disassembled diagram of the negative electrode structure in Comparative Example 1 of the present invention;

[0050] Figure 8 This is a disassembled diagram of the negative electrode structure in Comparative Example 2 of the present invention;

[0051] Figure 9 This is a cyclic stability test diagram of the negative electrode structure in Embodiment 1 of the present invention;

[0052] Figure 10 This is a cyclic stability test diagram of the negative electrode structure in Embodiment 2 of the present invention;

[0053] Figure 11 This is a cyclic stability test diagram of the negative electrode structure in Comparative Example 2 of the present invention.

[0054] Wherein, 1-first anti-electroplating layer; 2-first current collector; 3-first anti-electroplating mesh layer; 4-electroplating mesh layer; 5-second anti-electroplating mesh layer; 6-second current collector; 7-second anti-electroplating layer. Detailed Implementation

[0055] It should be understood that in the description of this invention, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0056] It should be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0057] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0058] In one specific embodiment, the present invention provides a negative electrode structure, the negative electrode structure comprising two composite current collector layers and an electroplated mesh layer sandwiched between the two composite current collector layers, the surface of the composite current collector layers being covered with through holes; the composite current collector layer comprising a current collector and an anti-electroplating layer disposed on one side surface of the current collector, the through holes in the composite current collector layer penetrating the current collector and the anti-electroplating layer, the anti-electroplating layers in the composite current collector layer all being disposed on the side surface of the current collector away from the electroplated mesh layer, and at least one anti-electroplating mesh layer being disposed between the current collector and the electroplated mesh layer.

[0059] Specifically, in this invention, the electroplating mesh layer represents a mesh layer capable of enhancing the electroplating of metal ions in the induced cell. For example, the metal ions can be lithium, sodium, zinc, or magnesium, which are metal anodes capable of being electroplated in a metallic state. Therefore, in this invention, the anti-electroplating mesh layer represents a mesh layer capable of preventing the electroplating of metal ions, meaning that metal ions will not be electroplated on the anti-electroplating mesh layer.

[0060] Specifically, the anti-plating mesh layer is made of an electroplating inhibiting material. This electroplating inhibiting material is one that can inhibit the electroplating of metal ions in the battery; that is, metal ions do not electroplat on the surface of the inhibiting material, thus preventing electroplating growth on the anti-plating mesh layer. Further, the electroplating inhibiting material includes one or a combination of at least two of nylon, polyethylene, polypropylene, polyvinyl alcohol, or polyvinyl chloride.

[0061] Specifically, the mesh size of the anti-electroplating mesh layer is 10–500 mesh, more preferably 30–200 mesh. The thickness of the current collector is 5–10 μm. The diameter of the through-hole is 500–2000 μm, preferably 1000–1500 μm. The spacing between the through-holes is 250–1000 μm, preferably 500–750 μm. The thickness of the anti-electroplating layer is 10–20 μm, and the material of the anti-electroplating layer includes an electroplating inhibiting material.

[0062] Specifically, the mesh size of the electroplated mesh layer is 10 to 500 meshes. Optionally, the size of the electroplated mesh layer is the same as that of the anti-electroplated mesh layer. The thickness of the electroplated mesh layer is 10 to 20 μm, wherein the mesh size is related to the mesh wire size, and therefore to the thickness.

[0063] Specifically, the material of the electroplating mesh layer includes an electroplating induction material. In this invention, the electroplating induction material refers to a material capable of inducing the electroplating growth of metal ions in the battery; that is, metal ions can undergo electroplating growth on the surface of the electroplating induction material. Furthermore, those skilled in the art can rationally select the electroplating induction material according to the different metal ions in the battery, thereby ensuring the electroplating effect of the metal ions. Further, the electroplating induction material includes zinc oxide.

[0064] Optionally, the electroplated mesh layer can be a mesh layer structure made directly from an electroplating inducing material, or it can be a mesh layer structure prepared from a substrate material, and then an electroplating inducing material is further coated on the surface of the substrate material to form an electroplated mesh layer with an electroplating inducing material on the surface.

[0065] Optionally, the anti-plating mesh layer can be a mesh layer structure made directly from a material that is electroplated, or it can be a mesh layer structure made from a base material and an electroplating inhibition material coated on the base material to form an electroplating mesh layer with an electroplating inhibition material on the surface.

[0066] In another specific embodiment, the present invention provides a method for preparing the above-mentioned negative electrode structure, the method comprising:

[0067] Two composite current collector layers with through holes are prepared. The composite current collector layer includes a current collector and an anti-electroplating layer stacked together. An electroplating mesh layer is set between the composite current collector layers. The current collector side of the composite current collector layer is close to the electroplating mesh layer. At least one anti-electroplating mesh layer is set between the current collector and the electroplating mesh layer to prepare the negative electrode structure.

[0068] Specifically, the preparation method of the composite current collector layer includes: after forming through holes on the surface of the current collector, forming an anti-electroplating layer on one side of the current collector, or after forming an anti-electroplating layer on the surface of the current collector, forming through holes on the surface of the current collector with the anti-electroplating layer. Further, the anti-electroplating layer is formed by coating.

[0069] The present invention also provides a battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode adopts the above-described negative electrode structure.

[0070] Example 1

[0071] This embodiment provides a negative electrode structure, such as Figure 1 As shown, the negative electrode structure includes a first anti-electroplating layer 1, a first current collector 2, a first anti-electroplating mesh layer 3, an electroplating mesh layer 4, a second anti-electroplating mesh layer 5, a second current collector 6, and a second anti-electroplating layer 7, which are stacked sequentially.

[0072] Among them, the first current collector 2 and the second current collector 6 are both copper foils with a thickness of 9μm, the first anti-electroplating layer 1 and the second anti-electroplating layer 7 are both PVA (polyvinyl alcohol) layers with a thickness of 15μm, the through hole diameter is 200μm, the through hole spacing is 600μm, and the through holes are arranged in a matrix. The substrate of the electroplating mesh layer 4 is a 40-mesh nickel-plated nylon mesh, and zinc oxide is coated on the nylon mesh. The first anti-electroplating mesh layer 3 and the second anti-electroplating mesh layer 5 are both 40-mesh nylon meshes.

[0073] This embodiment also provides a method for preparing the above-mentioned negative electrode structure, the method comprising:

[0074] After coating a copper foil with a thickness of 9 μm with a PVA aqueous solution, the PVA layer with a thickness of 15 μm is obtained by drying. A first composite current collector layer with a first anti-electroplating layer 1 and a first current collector 2 and a second composite current collector layer with a second anti-electroplating layer 7 and a second current collector 6 are prepared respectively.

[0075] Zinc oxide was coated onto the surface of a 40-mesh nickel-plated nylon mesh to prepare an electroplated mesh layer 4.

[0076] 40-mesh nylon mesh is used as the first anti-electroplating mesh layer 3 and the second anti-electroplating mesh layer 5, respectively.

[0077] The above-mentioned stacked layers are all stamped into circular structures with a diameter of 14mm and stacked. During the stacking process, the first current collector 2 and the second current collector 6 are arranged opposite each other on the side with the anti-electroplating layer. The first anti-electroplating mesh layer 3, the electroplating mesh layer 4 and the second anti-electroplating mesh layer 5 are stacked sequentially between the current collectors. After fixing, the negative electrode structure is obtained.

[0078] This embodiment also provides a battery, which includes the negative electrode structure described above.

[0079] Example 2

[0080] This embodiment provides a negative electrode structure. Compared with embodiment 1, the difference is that the through holes are arranged in a hexagonal honeycomb shape, the diameter of the through holes is 1 mm, the spacing between the through holes is 1 mm, and the rest of the structure is the same as that of embodiment 1.

[0081] This embodiment also provides a method for preparing the above-mentioned negative electrode structure. Compared with Example 1, the difference is that conventional copper foil with open space is used, and PVA is coated on the copper foil to prepare a composite current collector layer. The remaining steps and parameters are the same as in Example 1.

[0082] This embodiment also provides a battery, which includes the negative electrode structure described above.

[0083] Comparative Example 1

[0084] This comparative example provides a negative electrode structure, which, compared to Example 1, is as follows: Figure 2 As shown, the difference is that the first anti-electroplating mesh layer 3 and the second anti-electroplating mesh layer 5 are not provided. The through holes in the first current collector 2 are aligned and coincident with the mesh holes in the electroplating mesh layer 4. The other parameters are the same as in Example 1. That is, the negative electrode structure provided in this comparative example is the first anti-electroplating layer 1, the first current collector 2, the electroplating mesh layer 4, the second current collector 6, and the second anti-electroplating layer 7 stacked in sequence.

[0085] This comparative example also provides a method for preparing the above-mentioned negative electrode structure. Compared with Example 1, the difference is that the first anti-plating mesh layer 3 and the second anti-plating mesh layer 5 are not provided, and a step of aligning the through hole with the mesh hole is added.

[0086] Comparative Example 2

[0087] This comparative example provides a negative electrode structure that differs from Comparative Example 1 in that it does not align the through holes and the mesh holes.

[0088] The negative electrode structures of the above embodiments and comparative examples were used to prepare a 2032 type button battery. The preparation method included using the negative electrode structure as an electrode and using a lithium sheet with a thickness of 0.5 mm and a diameter of 16 mm as a non-circular electrode to prepare a 2032 type button battery.

[0089] The button cell batteries prepared above were subjected to charge-discharge tests. The test methods included: charging and discharging at 1.5 mA / cm². 2 The current was used to conduct a one-hour charge-discharge test and 100 cycles. Finally, an additional charge was performed, and the button battery was disassembled and the electrode condition was checked while it was charging. The electrode conditions after disassembly in Examples 1, 2, Comparative Example 1, and Comparative Example 2 are as follows: Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown.

[0090] Depend on Figures 5-8 Yes, comparative example 1 ( Figure 7 In Comparative Example 2, the through-holes of the current collector are aligned and overlapped with the mesh holes of the electroplating mesh layer, thereby limiting the metal ion electroplating position to the location where the current collector does not have through-holes. This effectively prevents the problem of dendritic electroplated metal protruding from the surface of the current collector. Figure 8 In the example shown, the through holes and mesh holes were not aligned. Figure 4 The dendritic electroplated metal protrudes from the surface of the current collector, which can cause short circuits. In contrast, in Embodiment 1 of this invention... Figure 5 (as shown) and Example 2 ( Figure 6 As shown in the figure, and in combination with Figure 3By setting an anti-plating mesh layer between the current collector and the electroplating mesh layer, it is not necessary to align the through holes and the mesh holes of the electroplating mesh layer. As shown in Example 2, the problem of lithium dendrite protrusion can also be effectively prevented by using a current collector with a conventional porous structure in the prior art. Even if the hole spacing and hole size are inconsistent with the size in the electroplating mesh layer, the problem of dendritic electroplated metal protrusion can still be prevented. Therefore, the addition of an anti-plating mesh layer in this invention can effectively reduce the difficulty of the manufacturing process while restricting the position of electroplated metal and ensuring the electroplating space. It is applicable to current collectors and electroplating mesh layers of different sizes.

[0091] Cyclic stability tests were performed on Examples 1, 2, and Comparative Example 2 above under the condition of 1.5 mA / cm². 2 The test was repeated for 200 hours, and the results are as follows: Figure 9 , Figure 10 and Figure 11 As shown.

[0092] pass Figure 9-11 As can be seen, these are all examples that do not use the method of aligning through holes and mesh holes. Example 1 ( Figure 9 (as shown) and Example 2 ( Figure 10 As shown in Comparative Example 2, due to the addition of an anti-plating mesh layer, stable charge-discharge characteristics can still be observed even without hole alignment and when the through-hole size is inconsistent with the mesh hole size. Figure 11 As shown in the figure, it can be confirmed that dendritic lithium protrusions occur inside the current collector, causing a short circuit inside the battery. Therefore, this application adds an anti-plating mesh layer, omits the hole alignment step, and does not require special processing of the current collector and the plating mesh layer. It can also control the metal plating position, thereby achieving stable battery cycle performance.

[0093] Capacity tests were performed on Example 1 and Comparative Example 1 described above. The test method included charging the electrode with a current of 1.5 mA from the irregularly shaped electrode, corresponding to 1–20 mAh / cm³. 2 The current density was used to evaluate the capacity from internal space saturation to lithium protrusion to the outer surface, thereby measuring the maximum lithium harvest capacity of each negative electrode structure. Five samples were used for each example, and the test results are shown in Table 1.

[0094] Table 1

[0095] Comparative Example 1 Example 1 #1 710mAh / g 930mAh / g #2 680mAh / g 910mAh / g #3 730mAh / g 880mAh / g #4 710mAh / g 902mAh / g #5 740mAh.g 970mAh / g average value 714mAh / g 918mAh / g

[0096] As can be seen from the table above, the electrode capacity of Example 1 is increased by 30% compared to Comparative Example 1. This effectively demonstrates that by inserting the anti-plating mesh layer, the space between current collectors is increased in this application, thereby increasing the capacity to hold metal ions. Thus, the energy density of the battery is improved by increasing the capacity of the electrode.

[0097] Through the above embodiments and comparative examples, the present invention provides space for the electroplating and desorption of metal ions in the battery by setting an electroplating mesh layer between the current collectors. Furthermore, by adding an anti-electroplation mesh layer between the current collector and the electroplating mesh layer, not only is the electroplating space for metal ions optimized, preventing the formed metal dendritic structure from penetrating through the through-holes of the current collector and causing short circuit risk, but the thickness of the anti-electroplation mesh layer can also be used to adjust the distance between the current collectors, that is, to control the size of the electroplating space for metal ions, thereby improving the capacity performance of the electrode. It has the characteristics of simple preparation process, high flexibility and low cost.

[0098] For negative electrode structures without an anti-plating mesh layer, when the mesh lines in the plating mesh layer intersect with the through-holes of the current collector, the metal grown on the plating lines can easily penetrate through the through-holes of the current collector, posing a risk of puncturing the separator. If the mesh holes in the plating mesh layer are aligned and coincident with the through-holes of the current collector, the metal plating growth is confined within the plating mesh layer, thus avoiding the above problem. However, the alignment process is complex, and it is difficult to ensure that each through-hole and mesh hole are aligned and coincident. In addition, to increase the distance between current collectors to improve capacity performance, the above structure can increase the thickness of the plating mesh layer by increasing the diameter of the mesh lines, but this will result in smaller mesh holes, so the effect of increasing internal space is not obvious. Although the specifications of the mesh lines and mesh holes can be matched to find a more suitable size, the matching of the through-hole size in the current collector and the mesh size of the plating mesh layer still has extremely high requirements.

[0099] In this invention, by adding an anti-plating mesh layer between the current collector and the electroplating mesh layer, it is not necessary to ensure that the through holes of the current collector and the mesh holes of the electroplating mesh layer are aligned and coincident during the preparation of the negative electrode structure. The anti-plating mesh layer achieves the function of restricting the growth of metal electroplating, optimizing the space for metal electroplating growth. Moreover, for increasing the electrode capacity by increasing the distance between current collectors, this invention only needs to change the thickness of the anti-plating mesh layer, which can be adjusted through a multi-layer structure. Furthermore, through the design of the anti-plating mesh layer structure, this invention can use different through hole sizes and electroplating mesh layer sizes, effectively reducing production costs.

[0100] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A negative electrode structure characterized by comprising: The negative electrode structure includes two composite current collector layers and an electroplated mesh layer sandwiched between the two composite current collector layers, and the surface of the composite current collector layers is covered with through holes. The composite current collector layer includes a current collector and an anti-electroplating layer disposed on one side surface of the current collector. In the composite current collector layer, the anti-electroplating layer is disposed on the side surface of the current collector away from the electroplating mesh layer. At least one anti-electroplating mesh layer is disposed between the current collector and the electroplating mesh layer.

2. The negative electrode structure according to claim 1, characterized by The material of the anti-electroplating mesh layer includes an electroplating inhibition material.

3. The negative electrode structure according to claim 2, characterized by The electroplating inhibition material includes one or a combination of at least two of nylon, polyethylene, polypropylene, polyvinyl alcohol, or polyvinyl chloride.

4. The negative electrode structure according to claim 1, wherein The mesh size of the anti-electroplation mesh layer is 10~500 mesh.

5. The negative electrode structure according to claim 4, wherein The mesh size of the anti-electroplation mesh layer is 30~200 mesh.

6. The negative electrode structure according to claim 1, wherein The thickness of the anti-electroplation mesh layer is 10~20μm.

7. The negative electrode structure according to claim 1, wherein The thickness of the current collector is 5~10μm.

8. The negative electrode structure according to claim 1, wherein The diameter of the through hole is 500~2000μm.

9. The negative electrode structure according to claim 1, wherein The spacing between the through holes is 250~1000μm.

10. The negative electrode structure according to claim 1, characterized in that, The thickness of the anti-electroplating layer is 10~20μm.

11. The negative electrode structure according to claim 1, characterized in that, The material of the anti-electroplating layer includes an electroplating inhibitor.

12. The negative electrode structure according to claim 1, wherein The mesh size of the electroplated mesh layer is 10~500 mesh.

13. The negative electrode structure according to claim 1, wherein The thickness of the electroplated mesh layer is 10~20μm.

14. The negative electrode structure according to claim 1, wherein The material of the electroplated mesh layer includes an electroplating induction material.

15. The negative electrode structure according to claim 14, wherein The electroplating induction material includes zinc oxide.

16. A method of producing the negative electrode structure according to any one of claims 1 to 15, characterized by, The preparation method includes: Two composite current collector layers with through holes are prepared. The composite current collector layer includes a current collector and an anti-electroplating layer stacked together. An electroplating mesh layer is set between the composite current collector layers. The current collector side of the composite current collector layer is close to the electroplating mesh layer. At least one anti-electroplating mesh layer is set between the current collector and the electroplating mesh layer to prepare the negative electrode structure.

17. The method of claim 16, wherein the method further comprises, The method for preparing the composite current collector layer includes: after setting a through hole on the surface of the current collector, setting an anti-electroplating layer on one side of the current collector, or after setting an anti-electroplating layer on the surface of the current collector, setting a through hole on the surface of the current collector with the anti-electroplating layer.

18. The method of claim 17, wherein, The anti-electroplating layer is applied by means of coating.

19. A battery, characterized by The battery includes a positive electrode, a negative electrode, a separator, and an electrolyte, wherein the negative electrode adopts the negative electrode structure described in any one of claims 1-15.

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