Current collector and secondary battery using same

Abstract

A current collector and a secondary battery using same. The current collector is made of a composite material (400), and the composite material (400) comprises a current collecting substrate (410) and a nano carbon layer (420). The nano carbon layer (420) is formed on and covers at least part of the surface of the current collecting substrate (410). The thickness of the nano carbon layer (420) is less than 1 micrometer (μm), and the mass ratio of carbon material in the nano carbon layer (420) is between 48% and 86%.

Description

Current collectors and secondary batteries using them Technical Field

[0001] This application relates to a secondary battery and materials thereof, and particularly to a current collector and a secondary battery using the same. Background Technology

[0002] Artificial graphite and natural graphite are currently the commonly used anode (also known as negative electrode) materials for lithium batteries. The current commercial graphite anode capacity is close to its theoretical capacity (372 mAh / g). Therefore, in order to improve the energy density of batteries, finding materials with higher capacity is the next major key.

[0003] Silicon-based anodes represent a major direction for the next stage of development. Silicon boasts a theoretical capacity of up to 4200 mAh / g, more than ten times that of current graphite anode materials. With abundant reserves and low cost, silicon is the most promising candidate material for next-generation lithium-ion battery anodes. However, during charging and discharging, silicon forms several crystalline phases in varying proportions during lithium insertion and extraction, resulting in a severe volume effect. The expansion rate during charging can reach 300% (compared to only 16% for traditional graphite anodes), while volume shrinkage during discharge. These repeated volume changes easily lead to problems such as silicon particle breakage, material pulverization, and electrode detachment, resulting in poor cycle performance. Simultaneously, the expansion process easily causes the SEI film (solid electrolyte interphase film) on the negative electrode surface to break down, only to reform during discharge. Therefore, the SEI film on the silicon surface is constantly in a dynamic process of destruction and reconstruction, ultimately leading to a continuous increase in SEI film thickness, increased interfacial impedance, and consumption of active materials, resulting in capacity decay and decreased coulombic efficiency, thus affecting the application of silicon anodes in lithium-ion secondary batteries.

[0004] In other words, due to the characteristics of silicon materials, the cycle performance and initial coulombic efficiency of batteries are relatively poor, which makes commercialization difficult in practical applications.

[0005] On the other hand, the cathode material of lithium batteries is generally composed of metal oxides, such as a combination of one or more oxides of manganese, nickel, cobalt, aluminum, and chromium. Common cathode materials include ternary materials, such as lithium aluminum cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or lithium iron phosphate (LiFePO4). However, the development of these cathode materials is limited, making it difficult to simultaneously achieve high cycle efficiency, low cost, and high safety.

[0006] Furthermore, in nickel-manganese-cobalt ternary / quaternary cathode materials, while increasing the nickel content can provide the advantage of high capacity, and nickel has advantages over cobalt such as low cost and abundant raw material sources, decreasing cobalt content leads to a decrease in the order of cations in the crystal lattice, making the material structure increasingly unstable. Increasing nickel content makes the material more susceptible to moisture absorption, promoting the reaction of lithium ions with water and carbon dioxide, resulting in impurity deposition and increased interfacial resistance at the cathode surface. Additionally, because nickel ions in the delithiated state are highly reactive and unstable, high nickel content makes it easier for the solution to react with the electrolyte, leading to capacity loss during charge-discharge cycles and accelerated capacity decay at high temperatures. As the nickel content increases, the material's safety decreases, potentially causing thermal runaway, short circuits, or explosions in lithium batteries under conditions of high temperature, overcharge, and over-discharge.

[0007] Lithium iron manganese phosphate (LiFeMn) is a relatively safer cathode material compared to high-nickel ternary cathodes. LiFeMn offers a relatively high operating voltage, but its volumetric energy density is lower than that of high-nickel ternary cathodes. In some applications, cathodes made with LiFeMn have an electrode compaction density of only about 2.2 g / cm³. 3 In comparison, electrodes made of ternary materials can achieve a compaction density of 3.4 g / cm³. 3 There is a significant difference between the two.

[0008] Some studies have proposed adding lithium iron manganese phosphate (LFP) to high-nickel ternary materials to create cathode materials, aiming to improve the safety of lithium-ion batteries. However, existing powdered LFP additives are difficult to fully and uniformly integrate with ternary materials, requiring a LFP blending ratio generally to be at least 25% to effectively enhance safety. Furthermore, due to the inherently low volumetric energy density of LFP, a high LFP blending ratio in ternary materials inevitably leads to a significant reduction in the volumetric energy density. Moreover, excessively high LFP ratios cause significant changes in electrode density, necessitating adjustments to the battery formulation to accommodate these density variations, which is detrimental to mass production and application across different products.

[0009] Besides lithium-ion batteries, sodium-ion batteries have also become a popular research area in recent years due to their low cost, abundant raw material reserves, and manufacturing process similar to lithium-ion batteries. However, the energy density of sodium-ion batteries is significantly lower than that of lithium-ion batteries, which is the biggest obstacle to their commercialization. Summary of the Invention

[0010] This application proposes a new current collector and a secondary battery using the same, to solve the problems mentioned in the prior art.

[0011] This application provides a current collector comprising a current collector substrate and a nano-carbon layer, wherein the nano-carbon layer covers at least a portion of the surface of the aluminum current collector substrate, the thickness of the nano-carbon layer is less than 1 μm, and the mass percentage of carbon material in the nano-carbon layer is between 48% and 86%, preferably between 60% and 66%.

[0012] The current collector can be a cathode current collector or an anode current collector.

[0013] This application provides a secondary battery comprising a cathode electrode, an anode electrode, and a separator disposed between the cathode electrode and the anode electrode. The cathode electrode includes a cathode material layer and a cathode current collector, and the anode electrode includes an anode material layer and an anode current collector. At least one of the cathode current collector and the anode current collector is made of a first composite material, the first composite material comprising a current collector substrate and a nano-carbon layer, wherein the nano-carbon layer forms and covers at least a portion of the surface of the current collector substrate. The thickness of the nano-carbon layer is less than 1 micrometer (μm), and the mass percentage of carbon material in the nano-carbon layer is between 48% and 86%.

[0014] The current collector exhibits excellent conductivity due to the coating of the nano-carbon layer, thereby significantly reducing the interfacial impedance between the aluminum current collector substrate and the active material. Furthermore, the current collector structure proposed in this application enhances the adhesion between the cathode / anode material layers and the current collector, contributing to improved overall battery efficiency. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0016] Figure 1 is a schematic diagram of the configuration of lithium secondary batteries according to some embodiments of this application;

[0017] Figure 2A is a schematic diagram of the composition of the cathode material layer in some embodiments of this application;

[0018] Figure 2B is a schematic diagram of the composition of the anode material layer in some embodiments of this application;

[0019] Figure 3A is a schematic cross-sectional view of the cathode active material in some embodiments of this application;

[0020] Figure 3B is a schematic cross-sectional view of the anodic active material in some embodiments of this application;

[0021] Figure 4 is a schematic diagram of the configuration of the current collector in some embodiments of this application;

[0022] Figure 5 is a schematic flowchart of the preparation method of cathode active material in some embodiments of this application;

[0023] Figures 6 and 7 are schematic flowcharts of the steps for preparing anodic active materials according to some embodiments of this application;

[0024] Figure 8 is a schematic flowchart of the steps of a method for preparing lattice-stabilized materials according to some embodiments of this application;

[0025] Figure 9 shows the X-ray diffraction analysis results of the anodic active material produced in Experiment Example 1;

[0026] Figure 10 is a scanning electron microscope image of the anodic active material produced in Experimental Example 4;

[0027] Figure 11 is a transmission electron microscope image of the anodic active material produced in Experiment Example 2;

[0028] Figure 12 shows the test results of the lithium secondary battery manufactured in Experiment Example 15 after activation;

[0029] Figure 13 shows the test results of the safety nail penetration test of the lithium secondary battery manufactured in Experimental Example 16 and Comparative Example 2.

[0030] Figure 14 shows the test conditions for the safety needle prick test in Experimental Example 16 and Comparative Example 2.

[0031] Figure 15 is a comparison of scanning electron microscope images of the positive electrodes manufactured in Experimental Example 19 and Comparative Example 6.

[0032] Figure 16 is a photograph of a nail penetration test performed on a lithium battery based on Comparative Example 6.

[0033] Figure 17 is a photograph of a nail penetration test conducted on a lithium battery made in Comparative Example 5.

[0034] Figure 18 is a photograph of the nail penetration test performed on the lithium battery made based on Experimental Example 18;

[0035] Figures 19A to 20B show a comparison of the differences in charge-discharge test results between secondary batteries of some embodiments of this application and different comparative examples;

[0036] Figure 21 shows a comparison of the tensile strength test results of secondary batteries from some embodiments of this application and comparative examples; and

[0037] Figures 22A and 22B compare the discharge test results of a sodium-ion battery made with a current collector according to an embodiment of this application and a comparative example. Detailed Implementation

[0038] To make the features and advantages of this application more apparent and understandable, specific embodiments of this application are described in detail below with reference to the accompanying drawings. The following description contains specific information relating to exemplary embodiments in this application. The drawings and accompanying detailed description in this application are merely exemplary embodiments. However, this application is not limited to these exemplary embodiments. Other variations and embodiments of this application will occur to those skilled in the art. Unless otherwise stated, the same or corresponding elements in the drawings may be indicated by the same or corresponding reference numerals. Furthermore, the drawings and illustrations in this application are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0039] For the purposes of consistency and ease of understanding, the same features are indicated by reference numerals in the exemplary drawings (although not in some examples). However, features in different embodiments may differ in other respects, and therefore should not be narrowly limited to the features shown in the drawings.

[0040] The terms "first," "second," and "third," etc., in the specification and accompanying drawings of this application are used to distinguish different objects, areas, levels, or steps, and are not used to describe a specific order (unless expressly required by the claims). Furthermore, the term "comprising" and any variations thereof are intended to cover a non-exclusive inclusion. The term "consisting of" is interpreted as an exclusive inclusion, meaning that any additional structural configuration and / or material addition is not within the scope of this term. However, those skilled in the art will understand that in actual testing, any material may be subject to unintended contamination or doped with trace impurities. These detected trace impurities, however, do not substantially affect the material, properties, and / or structure defined by the term, and therefore do not fall under the category of the aforementioned additional structural and / or material additions. This is stated in advance.

[0041] The terms "connection" or "coupling" used in this application do not imply that there can be no space between the objects. That is, the connection or coupling between two objects can mean that the two objects are directly connected / coupled to each other, or that they are connected / coupled to each other through other objects.

[0042] In all descriptions relating to specific numerical values ​​in this application, although not explicitly stated, they all contain the meaning of "approximately" or "substantially," meaning that these specific numerical values ​​will cover a possible range of numerical error to reflect possible unintended effects and deviations in process or material selection. The range of numerical error may include numerical changes that do not significantly alter the material structure, properties, or effects, such as a deviation of 0% to 10%, which is clear to those skilled in the art.

[0043] The spatial relationships mentioned in this application, such as "above", "below", "upward", "downward", "to the left", "to the right", etc., are all exemplary descriptions based on the relative positions presented in the diagrams and are not intended to limit the actual configuration of the material structure.

[0044] In this application, the terms anode and negative electrode are interchangeable, as are the terms cathode and positive electrode.

[0045] Figure 1 is a schematic diagram of the configuration of a secondary battery according to some embodiments of this application. Referring to Figure 1, the lithium secondary battery 10 of this embodiment includes a cathode electrode 11, a separator 12, and an anode electrode 13. The cathode electrode 11 includes a cathode material layer 110 and a cathode current collector 111, and the anode electrode 13 includes an anode material layer 130 and an anode current collector 131. The cathode electrode 11 and the anode electrode 13 are disposed on both sides of the separator 12. More specifically, the cathode material layer 110 is disposed between the cathode current collector 111 and the separator 12 (in the figure, it is disposed on the upper side of the separator 12), and the anode material layer 130 is disposed between the anode current collector 131 and the separator 12 (in the figure, it is disposed on the lower side of the separator 12).

[0046] When the secondary battery 10 is charged, cations are embedded from the cathode material layer and pass through the electrolyte and membrane 12 to be embedded into the anode material layer 130; conversely, when the secondary battery 10 is discharged, cations are embedded from the anode material layer 130 and pass through the electrolyte and membrane 12 to be embedded into the cathode material layer 110. At this time, due to the valence balance, electrons are output from the anode current collector 131.

[0047] In this embodiment, the cation may be, for example, lithium ions, sodium ions, or other ions with similar material properties, and this application is not limited thereto. When the cation is lithium ions, the secondary battery 10 is a lithium secondary battery (or lithium-ion battery). Similarly, when the anode ion is sodium ions, the secondary battery 10 is a sodium secondary battery (or sodium-ion battery).

[0048] In some embodiments, the cathode material layer 110 may be formed based on one or more cathode active materials, and at least one of the cathode active materials may be implemented, for example, as a composite material based on a high-nickel material (or cathode composite material / first composite material), wherein the high-nickel material refers to a material in which nickel is the metal at the center of the electrochemical redox reaction, and the molar ratio of nickel atoms in the material exceeds 50%, wherein the high-nickel material may, for example, include materials based on a lithium nickel oxide structure. The anode material layer 130 may be formed based on any feasible anode active material, and this application is not limited thereto, wherein one of the anode active materials may, for example, be implemented using a silicon particle-based composite material (or anode composite material / second composite material).

[0049] Using the silicon particle-based anode composite material as the anode active material of the lithium secondary battery 10 can solve the volume effect of silicon during charging and discharging, and provide better charging and discharging efficiency and capacity, while also providing better oxidation resistance. On the other hand, using the high-nickel material-based cathode composite material as the cathode active material of the lithium secondary battery 10 can reduce the risk of thermal runaway of the cathode material layer 110 and avoid excessive material expansion that could cause short circuits and explosions, thus further improving the safety of the lithium secondary battery 10.

[0050] The composition of the cathode material layer 110 and the specific structure of the cathode composite material are further illustrated below with reference to Figures 2A and 3A. Figure 2A is a schematic diagram of the composition of the cathode material layer in some embodiments of this application, and Figure 3A is a schematic diagram of the cross-sectional structure of the cathode active material in some embodiments of this application.

[0051] Referring simultaneously to Figures 2A and 3A, the cathode material layer 110 of this embodiment includes a cathode active material M1, which is implemented using a composite material 200 as shown in Figure 3A. Specifically, the composite material 200 comprises a high-nickel material 210 and a lattice-stabilizing material 220, wherein the lattice-stabilizing material 220 is formed on at least a portion of the surface of the high-nickel material 210. In other words, the lattice-stabilizing material 220 in the composite material 200 covers the high-nickel material 210 to form a double-layer structure.

[0052] In some embodiments, the cathode material layer 110 further includes a conductive material M2, wherein the conductive material M2 can be any material that is conductive and does not cause chemical changes in the battery, such as graphite (including artificial graphite or natural graphite), conductive carbon black, conductive fibers, conductive metal oxides or polyphenyl derivatives, etc.

[0053] In some embodiments, the cathode material layer 110 may further include an adhesive M3 for improving the bonding strength between the diaphragm 12 and the cathode current collector 111. In some embodiments, the cathode material layer 110 may further include a filler.

[0054] Specifically, the cathode active material / cathode material disclosed in this embodiment includes a composite material (or cathode composite material or high-nickel cathode composite material) formed of a high-nickel material and a lattice-stabilizing material. The lattice-stabilizing material is formed on at least a portion of the surface of the high-nickel material, and the nickel element accounts for at least 50% of the high-nickel material. This percentage can be atomic percentage or weight percentage. The lattice-stabilizing material is, for example, nano-sized lithium iron manganese phosphate (LiFe). 1-x Mn x Lithium iron phosphate (LiFePO4, LFMP) or lithium iron phosphate (LiFePO4) has an olivine structure, which can effectively stabilize the surface stability of high-nickel materials, reduce the risk of thermal runaway of cathode materials, and avoid the possibility of battery short circuit and explosion caused by excessive material expansion.

[0055] In addition, since the cathode composite material of this application embodiment has higher stability than general high-nickel materials, water can be used as a solvent system in addition to organic solvents during the preparation process. Compared with using organic solvents, water is non-toxic, harmless, safe, low-cost, readily available, and easy to recycle and reuse, thus further optimizing the cost and safety of the overall preparation process.

[0056] The composition of the anode material layer 130 and the specific structure of the composite material are further illustrated below with reference to Figures 2B and 3B. Figure 2B is a schematic diagram of the composition of the anode material layer in some embodiments of this application, and Figure 3B is a schematic diagram of the cross-sectional structure of the anode active material in some embodiments of this application.

[0057] Referring simultaneously to Figures 2B and 3B, the anode material layer 130 of this embodiment includes an anode active material M4, which is implemented using a composite material 300 as shown in Figure 3B. Specifically, the composite material 300 comprises silicon particles 310 and a high-entropy material 320, wherein the high-entropy material 320 is formed on at least a portion of the surface of the silicon particles 310. In other words, the high-entropy material 320 in the composite material 300 covers the silicon particles 310 to form a double-layer high-entropy silicon composite material.

[0058] In some embodiments, the anode material layer 130 further includes a conductive material M5, wherein the conductive material M5 can be any material that is conductive and does not cause chemical changes in the battery, such as graphite (including artificial graphite or natural graphite), conductive carbon black, conductive fibers, conductive metal oxides or polyphenyl derivatives and other conductive materials.

[0059] In some embodiments, the anode material layer 130 may further include an adhesive M6 for improving the bonding strength between the diaphragm 12 and the anode current collector 131. In some embodiments, the anode material layer 130 may further include a filler.

[0060] Specifically, the anodic active material / anodic material disclosed in this embodiment includes a composite material formed of silicon particles and a high-entropy material. The high-entropy material is formed on at least a portion of the surface of the silicon particles, and the high-entropy material is composed of at least five elements, with each element comprising no more than 50% of the high-entropy material. This percentage can be atomic percentage or weight percentage. The high-entropy material can also be referred to as a multi-component material, and the composite material can also be referred to as a high-entropy silicon composite material.

[0061] The composite material described above can increase the conductivity of silicon materials by coating them with a high-entropy material (such as the silicon particles mentioned above), thereby improving the conductivity of the silicon materials. The high-entropy material can be a material refined from five or more elements, overturning the previous concept that adding more elements to a material would make it brittle. Furthermore, the high-entropy material fully utilizes the effect of high randomness of multiple elements; by randomly distributing each element's atoms, it suppresses the formation of brittle compounds, resulting in greater toughness and increased oxidation resistance, thus inhibiting silicon expansion and increasing corrosion resistance. Therefore, the composite material formed by coating the surface of silicon materials with this high-entropy material can effectively improve the cycle life and expansion problems of lithium secondary batteries.

[0062] Optionally, the high-entropy material may include at least one of high-entropy alloys, high-entropy oxides, high-entropy polymers, and high-entropy ceramics.

[0063] More specifically, this embodiment discloses a method of combining a high-entropy material with at least one region on the surface of silicon particles to form the composite material. The composite material can be an amorphous oxide with a chemical formula, for example, Si1-(x+y+m+n+z)(M x N y A m B n X z )O p Where p = 0.1 to 2, M is, for example, a monovalent element, N is, for example, a divalent element, A is, for example, a trivalent element, B is, for example, a tetravalent element, and X is, for example, a transition metal element or other valence state element. In some embodiments, x, y, m, n, and z may each be less than or equal to 0.2.

[0064] In some embodiments, M can be lithium or sodium, N can be beryllium, magnesium, calcium, strontium, or barium, A can be boron, aluminum, gallium, or indium, B can be carbon, silicon, germanium, tin, or lead, and X can be any element. By mixing the aforementioned precursors of different elements and conducting a synthesis reaction between silicon materials, followed by appropriate heat treatment, a high-entropy material composite can be formed on the silicon material for use as a negative electrode material in lithium batteries.

[0065] The silicon particles coated with the high-entropy material can be sourced directly from pure silicon wafers or N-type or P-type silicon wafers commonly used in semiconductor manufacturing processes, with the doping amount of group III-V elements ranging from 0.001% to 2% by weight. During the preparation process, the silicon material can be ground into powder before the reaction, and the particle size can be controlled below 10 μm to facilitate subsequent processing of composite high-entropy materials.

[0066] Figure 4 is a schematic diagram of the configuration of a current collector according to some embodiments of this application. In this embodiment, the current collector is made of a composite material 400, which includes a current collecting substrate 410 and a nano-carbon layer 420, wherein the nano-carbon layer 420 covers at least a portion of the surface of the aluminum current collecting substrate 410, the thickness of the nano-carbon layer is less than 1 μm, and the mass percentage of carbon material in the nano-carbon layer is between 48% and 86%, preferably between 60% and 66%.

[0067] In some embodiments, the current collecting substrate 410 may be an aluminum-based current collecting substrate (hereinafter referred to as aluminum current collecting substrate 410).

[0068] In some embodiments, composite material 400 further includes a structural stabilizing material (not shown), which may be, for example, PVDF, PAA, CMC, PVA, or PAM, but this application is not limited thereto. The weight ratio of the structural stabilizing material to the current collector is, for example, between 1% and 20%, but this application is also not limited thereto.

[0069] It should be noted that although Figure 18 illustrates that the nano-carbon layer 420 is formed only on one side of the aluminum current collector substrate 410, this application is not limited to this. In some embodiments, the nano-carbon layer 420 may also be formed on both sides of the aluminum current collector substrate 410, wherein the thickness of the nano-carbon layer 420 formed on different surfaces will be less than 1 μm respectively.

[0070] The current collector made of composite material 400 can be used as a cathode current collector or an anode current collector. For ease of understanding, the following description uses cathode current collector 111 as an example, but this application is not limited to this. Those skilled in the art should also understand the configuration of the current collector in the embodiments of this application when it is used as an anode current collector through the following description.

[0071] The composite material 400 exhibits excellent conductivity due to the coating of the nano-carbon layer 420, thereby significantly reducing the interfacial impedance between the aluminum current collector substrate 410 and the cathode material layer 110. Furthermore, using the composite material 400 as the cathode current collector 111 enhances the adhesion between the cathode material layer 110 and the cathode current collector 111, contributing to improved overall battery efficiency.

[0072] The composite material 400 structure of this embodiment can be applied to the cathode current collector in lithium-ion batteries, sodium-ion batteries, or other types of secondary battery structures to achieve similar beneficial effects as described above and improve overall battery efficiency. Secondary batteries using the aforementioned composite material 400 can be further applied in the fields of automotive batteries, energy storage, consumer electronics batteries, supercapacitor batteries, and / or solid-state batteries, all achieving good results.

[0073] In some embodiments, the aluminum current collector substrate 410 used in the secondary battery may be an aluminum foil made of 1230A, 1235, or 8021 aluminum alloy, wherein the material properties of the aluminum foil include: a tempering degree of, for example, H18, and a tensile strength of 65-110 N / mm². 2 Or 180-200 N / mm 2 The elongation can be between 1% and 20%, but this application is not limited to this.

[0074] In some embodiments, the composite material 400 formed after coating the aluminum current collector substrate 410 with the nano-carbon layer 420 can have a sheet resistance / resistivity of less than 30 Ω·cm. Furthermore, a wipe test confirms that the nano-carbon layer 420 of the composite material does not detach, regardless of whether alcohol, NMP, electrolyte, or adhesive tape is used, demonstrating the structural stability of the composite material 400.

[0075] The following describes in detail an embodiment of a cathode material manufacturing method according to one of the present application, with reference to Figure 5. Figure 5 is a schematic flowchart of the preparation method of cathode active material according to some embodiments of the present application. Referring to Figure 5, in this embodiment, the preparation method of cathode active material includes the following steps: adding water, aqueous solution or organic solvent to a reaction tank as a solvent system (step S110); placing a high-nickel material in the reaction tank to mix with the solvent system (step S120); adding a lattice stabilizing material to the solvent system (step S130); and fully mixing the high-nickel material and the lattice stabilizing material in the solvent system to generate a cathode composite material, wherein in the structure of the cathode composite material, the lattice stabilizing material is attached to at least a portion of the surface of the high-nickel material (step S140).

[0076] In step S110, when water is used as the solvent system, the water can be deionized water or any type of purified water; when an aqueous solution is used as the solvent system, in addition to the above-mentioned types of water, any water-soluble substance can be added to assist subsequent reactions; when an organic solvent is used as the solvent system, the organic solvent may contain pyrrolidine compounds, such as N-methyl-2-pyrrolidone (NMP).

[0077] In step S120, the added high-nickel material can be any material with a nickel content higher than 50%, such as lithium nickel cobalt aluminum oxide (LiNi). 1-x-y Co x Al y O2, NCA), lithium nickel manganese cobalt oxide (LiNi) 1- x-y Mn x Co y O2, NMC) or LiNi 1-x-y Co x Mn yO2 (NCM), etc., are not limited to these. In this step, one or more of the following may also be added to the solution: conductive carbon, dispersant, surfactant, carbon precursor, thickener, and binder. The conductive carbon may be carbon nanotubes, graphene, Super P, acetylene black, Ketjen black, nanohorn, vapor-deposited carbon, or other conductive carbon materials. The binder may be, for example, polyvinylidene fluoride (PVDF) or styrene-butadiene rubber (SBR), but this application is not limited to these. The thickener may be, for example, carboxymethyl cellulose (CMC), but this application is also not limited to these.

[0078] In step S130, the lattice-stabilizing material may be, for example, LFMP. In some embodiments, lithium iron manganese phosphate may first be dissolved in a solvent (e.g., deionized water or NMP) to form nano- or submicron-sized particles dispersed in the solvent, and then added to the solution in step S120. The solid content of the LFMP in the solvent may be, for example, 30% to 50%, preferably 40%, but this application is not limited to this. The added LFMP accounts for 3% to 10% of the total cathode active material solution, preferably 5%, but this application is also not limited to this. The preparation process of the lattice-stabilizing material will be further illustrated in the following embodiment, Figure 8.

[0079] In step S140, the fully mixed high-nickel material and lattice-stabilized material will form the structure of cathode composite material M1 as shown in Figure 3A, which can be used as the cathode active material of lithium battery.

[0080] In some embodiments, the above-mentioned high-nickel composite material / cathode composite material can be coated onto a cathode current collector (e.g., copper foil or aluminum foil) after the solution is stirred evenly to prepare a positive electrode / cathode electrode (e.g., 11).

[0081] The following describes in detail an embodiment of the anode material manufacturing method according to one of the present application with reference to Figures 6 and 7, wherein Figures 6 and 7 are schematic flowcharts of the steps of the anode active material preparation method according to some embodiments of the present application. Referring first to Figure 6, in this embodiment, the anode active material preparation method includes the following steps: mixing water and an organic solvent in a reaction tank (step S210); placing silicon material in the reaction tank to contact the organic solvent (step S220); adding a precursor of multiple elements to the organic solvent, wherein the multiple elements are component elements of a high-entropy material (step S230); and fully mixing the precursor and silicon material in the organic solvent to generate a composite material / high-entropy silicon composite material containing silicon particles and a high-entropy material composed of the multiple elements (step S240).

[0082] The organic solvent may include one or more of the following: alcohols (such as methanol, ethanol, isopropanol IPA) and mixed solvents (such as dispersants, surfactants, conductive carbon, and carbon precursors), but this application is not limited thereto. The conductive carbon may be conductive carbon materials such as carbon nanotubes, graphene, Super P, acetylene black, Ketjen black, nano-angles, and vapor-deposited carbon.

[0083] In step S210, the mixing ratio of water and organic solvent can be 50 / 50, but this application is not limited to this.

[0084] In step S220, the added silicon material can be N-type, P-type silicon, or undoped group III-V modified pure silicon. The inorganic material includes one or more of the following: silicon, silicon powder, mixed powder of silicon and other metals, silicon-inorganic mixture, silicon alloy, silicon wafer, and waste slurry from silicon engineering, but this application is not limited thereto. The particle size of the silicon powder can be controlled, for example, between 1 μm and 10 μm.

[0085] In step S230, polyvinylpyrrolidone and silane may be added to the solution to prevent aggregation or precipitation during the formation of the composite material. The added polyvinylpyrrolidone may have a weight percentage concentration of 0.01% to 1%. In some embodiments, a weight percentage concentration of 0.01% to 0.7% of the added polyvinylpyrrolidone is preferred. Furthermore, the weight percentage concentration of silane in the organic solvent may be 10% to 80%. In some embodiments, a weight percentage concentration of 40% to 80% of the added silane is preferred.

[0086] In step S240, precursors of various elements undergo hydrolysis and polymerization reactions in a mixed solution of water and organic solvent to generate a high-entropy material, which is then mixed with a silicon material to form a colloidal suspension. The high-entropy material coagulates with the silicon material in the colloidal suspension, causing the high-entropy material to adhere to at least a portion of the surface of the silicon particles, thereby generating the composite material. In some embodiments, step S240 can be implemented using a sol-gel method.

[0087] In other words, in steps S210 to S240 above, the high-entropy silicon composite material is prepared by placing silicon powder in a solvent of water and organic solvent in an appropriate ratio, dissolving at least five different elements in a reaction tank, synthesizing them using an appropriate synthesis method (such as sol-gel method), drying, pulverizing, and then sintering at high temperature.

[0088] The following is a detailed implementation example of the above-described method for preparing the anodic active material, illustrated in Figure 7. Referring to Figure 7, the method for preparing the anodic active material in this embodiment includes the following steps: mixing water and an organic solvent in a reaction tank (step S310); processing silicon material into powdered silicon units (step S320); placing the silicon units in the reaction tank to contact the organic solvent (step S330); adding a precursor of multiple elements to the organic solvent, wherein the multiple elements are constituent elements of a high-entropy material (step S340); thoroughly mixing the precursor and the silicon units in the mixture of water and organic solvent to undergo hydrolysis and polymerization reactions, thereby generating a composite material containing silicon particles and a high-entropy material (step S350); drying the composite material (step S360); and heat-treating the dried composite material to generate a final powdered composite material (step S370).

[0089] Specifically, after steps S310 to S350, the composite material is essentially formed, but it is still mixed in the solution. Subsequent steps S360 and S370 allow for further separation of the composite material as the anolyte.

[0090] In the drying process step S360, the drying process can be carried out by drying the gel-like composite material in an inactive environment (such as an oxygen-free environment, which may be a vacuum or non-vacuum environment) at a first temperature, wherein the first temperature may be, for example, between 50°C and 150°C, preferably 120°C.

[0091] Next, in step S370 of the heat treatment, the dried gel can be heated at a second temperature in an inactive environment, wherein the second temperature may be, for example, between 900°C and 1500°C. In some embodiments, the heating time in step S270 may be between 2 and 5 hours. After heat treatment, the powdered composite material can be separated. The heat-treated composite material is then subjected to decomposition, dispersion, and classification treatment to obtain the finished anodic active material. The overall processing steps are simple and the processing time is short, allowing for mass production at a low cost.

[0092] Furthermore, in the high-entropy silicon composite material of this application embodiment, the silicon particles do not need to have a nanometer-scale particle size. The anode active material and its lithium secondary battery made from the high-entropy silicon composite material can still achieve good material properties such as high cycle performance and excellent coulombic efficiency. In this way, plasma treatment to electrolyze the silicon material is not required during the preparation process, which further reduces the cost of the preparation process and makes it more suitable for commercialization and mass production.

[0093] In some embodiments, the above-mentioned high-entropy silicon composite material / anode composite material can also be used to prepare an anode electrode by the following steps: mixing high-entropy material and graphite at a weight percentage of not less than 5% to prepare an anode active material accounting for 95% of the total anode weight percentage; adding single-walled carbon nanotubes at a weight percentage of 0.1%; adding a binder (e.g., PVDF at a weight percentage of 4.9%); dissolving the above mixture in an organic solvent (e.g., NMP); and coating the above solution onto a current collector (e.g., copper foil or aluminum foil) after stirring to prepare a negative electrode / anode electrode (e.g., 13).

[0094] In other embodiments, the adhesive described above may also be implemented using SBR. In embodiments using SBR as the adhesive, the added weight percentage may be 2.5%, and CMC may be added as a thickener, with the added CMC solids content weight percentage being, for example, 2.4%.

[0095] In the actual manufacturing process, the cathode electrode is dried at 110°C and then cold-pressed, trimmed, cut into sheets, slit, and welded with tabs to form a sheet for use as the cathode plate. The anode electrode is dried at 100°C and then cold-pressed, trimmed, cut into sheets, slit, and welded with tabs to form a sheet for use as the anode plate. The sheet-shaped cathode plates, separator, and anode plates are stacked alternately, and then an electrolyte solution is added and sealed in a mold to complete the preparation of the lithium secondary battery.

[0096] Figure 8 is a schematic flowchart of the preparation method of lattice-stabilized materials according to some embodiments of this application. Referring to Figure 8, in this embodiment, the preparation method of lattice-stabilized materials includes the following steps: adding a dispersant to an organic solvent (step S410); adding powdered LFMP to an organic solvent containing the dispersant to form a mixed material (step S420); and grinding the mixed material to generate a slurry-like lattice-stabilized material, wherein the LFMP particles are dispersed in the slurry-like lattice-stabilized material in a nano- or sub-micron-sized manner (step S430).

[0097] The organic solvent may, for example, contain a pyrrolidine compound (such as NMP), and the dispersant may, for example, contain one or more of the following: polyvinylpyrrolidone (PVP), p-diazepine, ethylene polyamine, N,N-dimethylaminopropylamine, diethylethanolamine, 9-octadeceneamine, and quaternary ammonium salts.

[0098] In some embodiments, the mixing ratio of the dispersant, organic solvent, and LFMP can be 1:15:6.5 to 25.

[0099] In some embodiments, step S410 may further add a suspending agent to stably suspend the LFMP particles dispersed in the slurry lattice-stabilized material in the slurry. The suspending agent may contain olefin compounds, such as polyvinylidene fluoride (PVDF), vinylidene fluoride-chlorotrifluoroethylene copolymer (VDF-CTFE), polyvinyl fluoride (PVF), ethylene-chlorotrifluoroethylene copolymer (ECTFE), perfluorosulfonic acid resin (XR resin), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), ethylene-tetrafluoroethylene copolymer (ETFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether (EPE), polychlorotrifluoroethylene (PCTFE), and polytetrafluoroethylene (PTFE), or one or more of these.

[0100] In some embodiments, the mixing ratio of the suspending agent, dispersant, organic solvent and LFMP can be 1:20:300:130 to 200.

[0101] In some embodiments, step S410 may also include a flame retardant, such as phosphazene, to endothermize and decompose the lithium-ion battery during thermal runaway, thereby delaying the thermal runaway reaction process.

[0102] In some embodiments, the mixing ratio of the phosphazene flame retardant, dispersant, organic solvent, and LFMP can be 1:2:30:13 to 20.

[0103] In some embodiments, step S420 may further include the addition of conductive carbon to enhance the conductivity and reactivity of the lattice-stabilized material. The conductive carbon may be conductive carbon materials such as carbon nanotubes (single-walled or multi-walled), graphene, Super P, acetylene black, Ketjen black, nano-angles, and vapor-deposited carbon.

[0104] In some embodiments, the mixing ratio of the conductive carbon, dispersant, organic solvent and LFMP can be 1:2:30:13 to 20.

[0105] The disclosure of the specific values ​​mentioned above is only a preferred choice for the specific experimental conditions described above. In fact, this embodiment discloses not only the specific values ​​mentioned above, but also an effective offset range that can achieve similar or the same preferred effect, such as ±15%. In other words, if a specific value is specified in the claims, the corresponding value can be equally included within its deviation range of ±15% (provided that the effect can be achieved), which is stated here first.

[0106] It should be noted that the structures and preparation methods of the cathode and anode active materials disclosed in the above embodiments can be used alone or in combination. For example, the cathode active material implemented with a high-nickel composite material as described in the above embodiments, when combined with a general anode structure / material to fabricate a lithium secondary battery, can also provide the effect of optimizing battery safety. Similarly, the anode active material implemented with a high-entropy silicon composite material as described in the above embodiments, when combined with a general cathode structure / material to fabricate a lithium secondary battery, can also provide the effect of improving cycle efficiency and increasing capacity.

[0107] When the high-nickel composite material and high-entropy silicon composite material of the above embodiments are used together to prepare the cathode and anode electrodes of lithium secondary batteries, the efficiency and safety of the lithium secondary batteries can be further improved. At the same time, the environmental protection requirements can be met by using a process system with pure water as a solvent, providing the market with batteries that are both safe and have high capacity. Therefore, the technical effect achieved by the lithium secondary battery made by combining the two composite materials is far superior to that of implementing them alone, and it can bring unexpected advantages. The following are several experimental examples to illustrate the specific examples of the structure and preparation process of the anode composite material, the lattice stabilizing material, and the cathode composite material with the added lattice stabilizing material of the present application. Among them, experimental examples 1 to 6 are experimental examples of the preparation of anode active materials, experimental examples 7 to 11 are experimental examples of the preparation of lattice stabilizing materials, and experimental examples 12 to 20 are experimental examples of the preparation of cathode active materials and lithium batteries using them.

[0108] The procedure for Experiment Example 1 is as follows: 500g of water and 50% organic solvent (ethanol, 4% graphene, 5% polyvinylpyrrolidone) are added to a reaction vessel. The solvent in the reaction vessel contains 2% aluminum chloride, 0.6% magnesium nitrate, 0.2% lithium carbonate, and 80% silane. After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 1 and 10 μm is added and mixed. After uniform stirring and dispersion, the mixture is dried at 120℃ and then subjected to high-temperature heat treatment at 1100℃ under nitrogen for 2 hours. This process involves decomposition, dispersion, and classification to produce high-entropy silicon composite material powder.

[0109] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0110] Figure 9 shows the X-ray diffraction (XRD) analysis results of the anodic active material produced in Experimental Example 1. The XRD analysis results of the powder from Experimental Example 1, compared with the silicon standard peak (ICSD-51688-Si), confirm that amorphous silicon compounds are generated during the process.

[0111] The procedure for Experiment Example 2 is as follows: 500g of water and 50% organic solvent were added to a reaction vessel. The organic solvent was isopropanol, while the water contained 4% carbon nanotubes and polyvinylpyrrolidone. The solvent in the reaction vessel contained 2% aluminum nitrate, 0.6% barium nitrate, 0.2% lithium carbonate, and 80% silane (dissolved only in the organic solvent). After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 1 and 10 μm was added and mixed. After uniform stirring and dispersion, the mixture was dried at 120℃ and then subjected to high-temperature heat treatment at 1100℃ under nitrogen for 3 hours. This process was followed by decomposition, dispersion, and classification to produce high-entropy silicon composite material powder.

[0112] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0113] Figure 11 is a transmission electron microscope (TEM) image of the anodic active material produced in Experimental Example 2. Referring to Figure 11, when the powder sample obtained in Experimental Example 2 is observed under a transmission electron microscope, it can be seen that an amorphous silicon compound of about 20 nm is generated on the surface of the original silicon particles, coating the surface of the silicon anode.

[0114] The procedure for Experiment Example 3 is as follows: 500g of aqueous solution and 50% organic solvent were added to a reaction vessel. The organic solvent was ethanol, while the water contained 6% fructose and ammonia. The solvent in the reaction vessel contained 2% aluminum hydroxide, 0.6% magnesium hydroxide, and 0.25% lithium hydroxide. The solid content of silane in the solvent was 80%. After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 0.5 and 1μm was added and mixed. After uniform stirring and dispersion, the mixture was dried at 120℃ and then subjected to high-temperature heat treatment at 1100℃ under nitrogen for 3 hours. The resulting particles were then decomposed, dispersed, and graded to produce high-entropy silicon composite material powder.

[0115] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0116] The procedure for Experiment Example 4 is as follows: 500g of water and 50% organic solvent (ethanol) were added to a reaction vessel. The water contained 4% carbon nanotubes and polyvinylpyrrolidone. The solvent in the reaction vessel contained 2% aluminum chloride, 0.6% calcium carbonate, 0.2% lithium carbonate, and 80% silane. After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 1 and 10 μm was added and mixed. After uniform stirring and dispersion, the mixture was dried at 120℃ and then subjected to high-temperature heat treatment at 1100℃ under nitrogen for 3 hours. This process was followed by decomposition, dispersion, and classification to produce high-entropy silicon composite material powder.

[0117] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0118] Figure 10 is a scanning electron microscope (SEM) image of the anolyte produced in Experiment 4. Referring to Figure 10, the powder sample obtained in Experiment 4 was observed using a scanning electron microscope. It can be seen that uniform carbon nanotubes (NCTs) formed by this process are coated on the silicon material, forming a good conductive network.

[0119] The procedure for Experiment Example 5 is as follows: 500g of water and 50% organic solvent (ethanol, 4% graphene, 5% polyvinylpyrrolidone) are added to a reaction vessel. The solvent in the reaction vessel contains 2% aluminum nitrate, 0.6% barium nitrate, 0.2% lithium carbonate, and 80% silane. After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 1 and 10 μm is added and mixed. After uniform stirring and dispersion, the mixture is dried at 120°C and then subjected to high-temperature heat treatment at 1100°C under nitrogen for 3 hours. This process involves decomposition, dispersion, and classification to produce high-entropy silicon composite material powder.

[0120] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0121] The procedure for Experiment Example 6 is as follows: 500g of water and 50% organic solvent were added to a reaction vessel. The organic solvent was ethanol, while the water contained 4% graphene and polyvinylpyrrolidone. The solvent in the reaction vessel contained 2% aluminum nitrate, 0.6% barium nitrate, 0.2% lithium carbonate, 0.005% yttrium nitrate, and 80% silane. After uniform stirring for 2 hours, 50g of silicon powder with a particle size controlled between 1 and 10 μm was added and mixed. After uniform stirring and dispersion, the mixture was dried at 120℃ and then subjected to high-temperature heat treatment at 1100℃ under nitrogen for 3 hours. The resulting particles were then decomposed, dispersed, and graded to produce high-entropy silicon composite material powder.

[0122] A coin-shaped battery with a diameter of 20 mm and a height of 3.2 mm is manufactured based on the aforementioned anode active material, namely high-entropy silicon composite material powder. The high-entropy silicon composite material contains at least 5% silicon powder by weight; a mixture of artificial graphite and anode active material accounts for 80% of the total anode by weight; superconducting carbon black (super P) conductive material accounts for 10% of the total anode by weight; and polyvinylidene fluoride (PVDF) binder accounts for 10% of the total anode by weight.

[0123] Table 1

[0124] Table 1 above summarizes the charge / discharge efficiency characteristics of Experimental Examples 1 to 6 and Comparative Example 1. Comparative Example 1 is a coin-shaped battery constructed using Shin-Etsu Chemical's silicon-carbon anode active material (model: KSC-1265). The anode / anode active material used in this example is not the composite material proposed in this application. In the table, "0.1C" refers to the secondary battery being charged / discharged at 1 / 10 of its rated capacity, and "1C" refers to the secondary battery being charged / discharged at 1 times its rated capacity. For example, for a secondary battery with a rated capacity of 1000mAh, 1C means discharging the secondary battery at a current of 1000mA. The following related sections can be deduced similarly.

[0125] According to the experimental data disclosed in Table 1, the high-entropy silicon composite material produced after silicon powder is modified outperforms commercially available silicon powder in terms of conductivity, capacity, initial cycle efficiency, and subsequent cycle efficiency.

[0126] Table 2

[0127] Table 2 above summarizes the expansion characteristics data of Experimental Examples 1 to 6 and Comparative Example 1. According to the data of each experimental example disclosed in Table 2, the expansion of the high-entropy silicon composite material produced after silicon powder is modified is further reduced at the silicon anode.

[0128] The preparation of lattice-stable materials is further illustrated below with experimental examples 7 to 11.

[0129] The procedure for Experiment Example 7 is as follows: 300 grams of NMP organic solvent and 200 grams of LFMP powder were placed in a vertical grinding jar and ground using a vertical sand mill to obtain LFMP powder in the submicron scale range of Experiment Example 7.

[0130] The procedure for Experiment Example 8 is as follows: 20 grams of PVP as a dispersant and 300 grams of NMP organic solvent are placed in a vertical grinding jar and stirred to dissolve. After the PVP is completely dissolved, 180 grams of LFMP powder are added, and the mixture is ground in a vertical sand mill to obtain the LFMP slurry of Experiment Example 8.

[0131] The procedure for Experiment Example 9 is as follows: 20 grams of PVP as a dispersant, 1.3 grams of PVDF as a suspending agent and 300 grams of NMP organic solvent are placed in a vertical grinding jar and stirred to dissolve. After PVP and PVDF are completely dissolved, 178.7 grams of lithium manganese iron phosphate powder are added. The mixture is then ground in a vertical sand mill to obtain the LFMP slurry of Experiment Example 9.

[0132] The procedure for Experiment Example 10 is as follows: 20 grams of PVP as a dispersant, 1.3 grams of PVDF as a suspending agent and 300 grams of NMP organic solvent are placed in a vertical grinding jar and stirred to dissolve. After PVP and PVDF are completely dissolved, 168.7 grams of LFMP powder and 10 grams of multi-walled carbon nanotubes as conductive carbon are added. The mixture is then ground in a vertical sand mill to obtain the LFMP slurry of Experiment Example 10.

[0133] The procedure for Experiment Example 11: 20g of PVP as a dispersant, 1.3g of PVDF as a suspending agent, 10g of phosphazene flame retardant and 300g of NMP organic solvent were placed in a vertical grinding jar and stirred to dissolve. After PVP and PVDF were completely dissolved, 158.7g of LFMP powder and 10g of multi-walled carbon nanotubes as conductive carbon were added. The mixture was then ground in a vertical sand mill to obtain the LFMP slurry of Experiment Example 10.

[0134] It should be noted that the dosages of PVP, PVDF, NMP, and LFMP in the above experimental examples are only illustrative examples of some feasible experiments in the embodiments of this application, and the embodiments of this application are not limited to the above numerical ranges. More specifically, in other experimental examples, the LFMP slurry can be generated using dosage ratios within the following ranges:

[0135] In this context, A, B, C, and D represent the dosages of PVP, PVDF, NMP, and LFMP, respectively.

[0136] Table 3

[0137] Table 3 above shows the results of stability tests (test temperature 55°C) conducted on the lattice-stabilized materials prepared in Examples 7 to 11. As can be seen from the data of each experimental example disclosed in Table 3, the LFMP slurry prepared by mixing and grinding dispersant, organic solvent and LFMP has better stability.

[0138] The following examples 12 to 20 further illustrate the cathode active material and the preparation of lithium batteries using it.

[0139] The procedure for Experiment Example 12 is as follows: High-nickel material, conductive agent superconducting carbon (Super-P), and binder PVDF are mixed and dissolved in NMP at a mass ratio of 97:1.5:1.5 to prepare a positive electrode slurry with a certain viscosity. Then, a well-dispersed nano-LFMP slurry with a solid content of 40% is added and the total amount added is 5% of the original solid content of the positive electrode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0140] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 12, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0141] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes are added to the negative electrode slurry, wherein the solid content of the single-walled carbon nanotubes is 0.1% by weight. PVDF is added to the negative electrode slurry, wherein the solid content of the PVDF is 4.9% by weight. The negative electrode slurry is coated onto copper foil using NMP as a solvent system after being completely dissolved in NMP and stirred evenly to prepare the anode electrode. After drying at 110°C, it is cold-pressed, edge-trimmed, cut into sheets, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0142] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0143] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0144] The procedure for Experiment Example 13 is as follows: High-nickel cathode material, carbon nanotubes, and PVDF binder are mixed and dissolved in NMP at a mass ratio of 98.5:0.5:1 to prepare a cathode slurry with a certain viscosity. Then, a well-dispersed nano-LFMP slurry with a solid content of 40% is added, and the total amount added is 5% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0145] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 13, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0146] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes are added to the negative electrode slurry, wherein the solid content of the single-walled carbon nanotubes is 0.1% by weight. PVDF is added to the negative electrode slurry, wherein the solid content of the PVDF is 4.9% by weight. The negative electrode slurry is coated onto copper foil using NMP as a solvent system after being completely dissolved in NMP and stirred evenly to prepare the anode electrode. After drying at 110°C, it is cold-pressed, edge-trimmed, cut into sheets, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0147] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0148] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0149] The procedure for Experiment Example 14 is as follows: High-nickel cathode material, carbon nanotubes, and PVDF binder are mixed and dissolved in NMP at a mass ratio of 98.5:0.5:1 to prepare a cathode slurry with a certain viscosity. Then, a well-dispersed nano-LFMP slurry with a solid content of 40% is added, and the total amount added is 5% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0150] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and tab-welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 14, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0151] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes (SUVs) are added to the negative electrode slurry, wherein the SUV solid content is 0.1% by weight. SBR is added to the negative electrode slurry, wherein the SBR solid content is 2.5% by weight. CMC is added to the negative electrode slurry as a thickener, wherein the CMC weight percentage is 2.4%. The negative electrode slurry is coated onto copper foil using deionized water as a solvent system after being completely dissolved in deionized water and stirred evenly to prepare the anode electrode. After drying at 100°C, it is cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0152] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0153] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0154] The procedure for Experiment Example 15 is as follows: High-nickel cathode material, carbon nanotubes, SBR binder and CMC thickener are mixed and dissolved in deionized water at a mass ratio of 95.5:0.5:2:2 to prepare a cathode slurry with a certain viscosity. Then, a well-dispersed water-based slurry of nano-LFMP is added, wherein the solid content of the water-based slurry of nano-LFMP is 40%, and the total amount added is 5% of the solid content of the original cathode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0155] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 100°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 15, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0156] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes (SUVs) are added to the negative electrode slurry, wherein the SUV solid content is 0.1% by weight. SBR is added to the negative electrode slurry, wherein the SBR solid content is 2.5% by weight. CMC is added to the negative electrode slurry as a thickener, wherein the CMC weight percentage is 2.4%. The negative electrode slurry is coated onto copper foil using deionized water as a solvent system after being completely dissolved in deionized water and stirred evenly to prepare the anode electrode. After drying at 100°C, it is cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0157] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0158] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0159] Figure 12 shows the test results of the lithium secondary battery manufactured in Experimental Example 15 after activation. Referring to Figure 12, it can be seen that the high-nickel cathode of the water-solvent system prepared in Experimental Example 15 did not exhibit any expansion problem after activation.

[0160] The procedure for Experiment Example 16 is as follows: High-nickel cathode material, carbon nanotubes, SBR binder and CMC thickener are uniformly mixed and dissolved in deionized water at a mass ratio of 95.5:0.5:2:2 to prepare a cathode slurry with a certain viscosity. Then, a well-dispersed water-based slurry of nano-LFMP is added, wherein the solid content of the water-based slurry of nano-LFMP is 40%, and the total amount added is 5% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0161] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 100°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 16, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0162] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes are added to the negative electrode slurry, wherein the solid content of the single-walled carbon nanotubes is 0.1% by weight. PVDF is added to the negative electrode slurry, wherein the solid content of the PVDF is 4.9% by weight. The negative electrode slurry is coated onto copper foil using NMP as a solvent system after being completely dissolved in NMP and stirred evenly to prepare the anode electrode. After drying at 110°C, it is cold-pressed, edge-trimmed, cut into sheets, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0163] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0164] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0165] Figure 13 shows the test results of the safety nail penetration test of the lithium secondary battery manufactured in Experimental Example 16 and Comparative Example 2. Comparative Example 2 involved mixing high-nickel positive electrode material, superconducting carbon (Super-P) as a conductive agent, and polyvinylidene fluoride (PVDF) as a binder in a mass ratio of 97:1.5:1.5 and dissolving them uniformly in N-methyl-2-pyrrolidone (NMP) to prepare a positive electrode slurry with a certain viscosity. This slurry was coated onto an aluminum foil current collector, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and had its tabs welded to produce the lithium battery positive electrode sheet. Additionally, at least 5% by weight of nano-silicon powder was mixed with graphite to prepare the anode active material, wherein the anode active material accounted for 95% of the total anode weight percentage. 0.1% by weight of single-walled carbon nanotubes and 4.9% by weight of PVDF binder were added to the negative electrode slurry. The entire mixture was then dissolved in NMP, stirred uniformly, and coated onto copper foil to prepare the anode electrode. After drying at 110℃, the lithium battery negative electrode sheet is produced by cold pressing, edge trimming, sheet cutting, slitting, and tab welding. Comparative Example 2 uses a lithium secondary battery configuration structure similar to the aforementioned experimental example, and uses the above-mentioned lithium battery positive and negative electrode sheets to form an aluminum-molded lithium secondary battery for encapsulation activation testing.

[0166] In other words, the cathode active material of the positive / cathode electrode in the lithium battery prepared by the preparation process of Comparative Example 2 does not contain the cathode composite material described in the above experimental example.

[0167] Referring to Figure 13, the safety nail penetration test conducted on the lithium batteries prepared in Experimental Example 16 and Comparative Example 2 revealed that Experimental Example 16 did not produce smoke (as shown on the right side of Figure 13), while Comparative Example 2 showed signs of smoke and damage (as shown on the left side of Figure 13). The test conditions for the safety nail penetration test and the puncture results of the control group (Comparative Example 2) are shown in Figure 14.

[0168] The procedure for Experiment Example 17 is as follows: High-nickel cathode material, carbon nanotubes, SBR binder and CMC thickener are uniformly mixed and dissolved in deionized water at a mass ratio of 95.5:0.5:2:2 to prepare a cathode slurry with a certain viscosity. Then, a slurry with well-dispersed nano-LFMP water as solvent is added. The solid content of the nano-LFMP water-based slurry is 40%, and the total amount added is 5% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material with LFMP coated on the high-nickel material as the cathode active material.

[0169] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 100°C, and then cold-pressed, trimmed, cut, slit, and tab-welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 17, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0170] At least 5% by weight of a composite silicon high-entropy material and graphite are mixed to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes (SUVs) and graphene are added to the negative electrode slurry, wherein the solid content of SUVs and graphene is 0.1% by weight, respectively. SBR is added to the negative electrode slurry, wherein the solid content of SBR is 2.5% by weight. CMC is added to the negative electrode slurry as a thickener, wherein the CMC weight percentage is 2.4%. The negative electrode slurry is coated onto copper foil using deionized water as a solvent system after being completely dissolved in deionized water and stirred evenly to prepare the anode electrode. After drying at 100°C, it is cold-pressed, edge-trimmed, cut into sheets, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0171] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0172] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum mold for encapsulation and activation for testing.

[0173] The procedure for Experiment 18 is as follows: High-nickel cathode material NCM811, binder PVDF, and multi-walled carbon nanotubes (4% MWCNT) are mixed and dissolved in NMP organic solvent at a solid content mass ratio of 87.3:2:1 to prepare a cathode slurry with a certain viscosity. Then, the LFMP slurry prepared based on Experiment 10 is added to the cathode slurry, and the total amount of LFMP slurry added is 9.7% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material coated with LFMP on the cathode material as the cathode active material.

[0174] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 18, the above-mentioned positive electrode was further combined with a negative electrode prepared by the following process (but this application is not limited to this) to construct a lithium battery for testing, wherein the preparation process of the negative electrode includes:

[0175] At least 5% by weight of a composite silicon high-entropy material is mixed with graphite to prepare the anode active material, wherein the anode active material accounts for 95% of the total anode weight. Single-walled carbon nanotubes (SWCNTs) are added to the negative electrode slurry, wherein the solid content of SWCNTs is 0.1% by weight. PVDF is added to the negative electrode slurry, wherein the solid content of PVDF is 4.9% by weight. The negative electrode slurry is coated onto copper foil using NMP as a solvent system after being completely dissolved in NMP and stirred evenly to prepare the anode electrode. After drying at 110°C, it is cold-pressed, edge-trimmed, cut, slit, and the tabs are welded to produce the negative electrode / negative electrode sheet for the lithium battery.

[0176] The aforementioned positive and negative electrode sheets serve as the positive and negative electrode plates, respectively, and are configured as a lithium secondary battery and tested using the following method:

[0177] Set up positive and negative electrode plates; set up a separator between the positive and negative electrode plates to define the containment area; after adding the two positive and negative electrodes to the electrolyte solution in an alternating stack, place them in an aluminum-plastic film for encapsulation and activation for testing.

[0178] The procedure for Experiment 19 is as follows: High-nickel cathode material NCM811, binder PVDF, and multi-walled carbon nanotubes (4% MWCNT) are mixed and dissolved in NMP organic solvent at a solid content mass ratio of 92.15:2:1 to prepare a cathode slurry with a certain viscosity. Then, the LFMP slurry prepared based on Experiment 10 is added to the cathode slurry, and the total amount of LFMP slurry added is 4.85% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material coated with LFMP on the cathode material as the cathode active material.

[0179] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 19, the above-mentioned positive electrode is further combined with a negative electrode similar to that described in Experimental Example 18 (but this application is not limited to this) to construct a lithium battery for testing. The preparation process of the negative electrode and the configuration of the lithium battery can be referred to the above-mentioned experimental examples, and will not be repeated here.

[0180] The procedure for Experiment Example 20 is as follows: Lithium cobalt oxide cathode material (LCO), binder (PVDF), and multi-walled carbon nanotubes (4% MWCNT) are mixed and dissolved in NMP organic solvent at a solid content mass ratio of 92.15:2:1 to prepare a cathode slurry with a certain viscosity. Then, the LFMP slurry prepared based on Experiment Example 10 is added to the cathode slurry, and the total amount of LFMP slurry added is 4.85% of the original solid content of the cathode slurry. The mixture is then mixed to prepare a cathode composite material coated with LFMP on the cathode material as the cathode active material.

[0181] Subsequently, the cathode active material is coated onto the current collector aluminum foil, dried at 110°C, and then cold-pressed, trimmed, cut, slit, and the tabs are welded to produce the positive electrode / positive electrode sheet for the lithium battery. In Experimental Example 20, the above-mentioned positive electrode is further combined with a negative electrode similar to that described in Experimental Example 18 (but this application is not limited to this) to construct a lithium battery for testing. The preparation process of the negative electrode and the configuration of the lithium battery can be referred to the above-mentioned experimental examples, and will not be repeated here.

[0182] Table 4

[0183] As can be seen from the experimental data disclosed in Table 4 above, in different positive and negative electrode systems, such as water-based solvent systems or NMP solvent systems, the silicon anode material composite high-entropy material produced after silicon powder is modified outperforms the silicon powder of Comparative Example 1 in terms of conductivity, capacity, first cycle efficiency, and multiple subsequent cycle efficiency.

[0184] Table 5

[0185] Table 5 above summarizes the expansion characteristic data of Experimental Examples 12 to 17 and Comparative Example 1. As can be seen from the data of each experimental example disclosed in Table 5, the expansion of the silicon anode material composite high-entropy material produced after silicon powder modification is further reduced. Furthermore, applying this to LFMP composite high-nickel cathode materials in a process using pure water as a solvent can meet environmental protection requirements and maintain the safety of lithium batteries, providing the market with batteries that are both safe and have high capacity.

[0186] Table 6

[0187] Table 6 summarizes the material property data of Experimental Examples 15 to 17 and Comparative Examples 3 to 5, wherein the preparation methods of Comparative Examples 3 to 6 are described below:

[0188] Comparative Example 3: LFMP was used as the positive electrode material, combined with PVDF binder and multi-walled carbon nanotubes (4% MWCNT) at a solid content mass ratio of 97:2:1 and dissolved evenly in NMP organic solvent to prepare a positive electrode slurry with a certain viscosity, which was then used to prepare the positive electrode / positive electrode sheet.

[0189] Comparative Example 4: High-nickel cathode material NCM811, binder PVDF, and multi-walled carbon nanotubes (4% MWCNT) were mixed and dissolved in NMP organic solvent at a solid content mass ratio of 38.8:2:1 to prepare a cathode slurry with a certain viscosity. Then, LFMP powder that had not been treated in Experiments 7 to 11 above was added to the cathode slurry to prepare a cathode electrode / cathode sheet. The total amount of LFMP slurry added was 58.2% of the original solid content of the cathode slurry.

[0190] Comparative Example 5: High-nickel cathode material NCM811, binder PVDF, and multi-walled carbon nanotubes (4% MWCNT) were mixed and dissolved in NMP organic solvent at a solid content mass ratio of 77.6:2:1 to prepare a cathode slurry with a certain viscosity. Then, LFMP powder that had not been treated in Experiments 7 to 11 above was added to the cathode slurry to prepare a cathode electrode / cathode sheet. The total amount of LFMP slurry added was 19.4% of the original solid content of the cathode slurry.

[0191] Comparative Example 6: High-nickel cathode material NCM811, binder PVDF and multi-walled carbon nanotubes (4% MWCNT) were mixed and dissolved in NMP organic solvent at a solid content mass ratio of 97:2:1 to prepare a cathode slurry with a certain viscosity. No LFMP was added, and the cathode electrode / cathode sheet was made accordingly.

[0192] As shown in Table 6 above, compared with the positive electrode made with LFMP (Comparative Example 3) or the positive electrode made by adding untreated LFMP powder to the high-nickel positive electrode material NCM811 (Comparative Example 4), the positive electrodes prepared by the method of preparing lattice-stabilized materials described in Figure 8 in Experimental Examples 10-12 all have better electrode density.

[0193] Figure 15 is a comparison of scanning electron microscope (SEM) images of the positive electrodes fabricated in Experimental Example 19 and Comparative Example 6. By observing the microscopic surface morphology of the positive electrodes fabricated in Experimental Example 19 and Comparative Example 6 using SEM, a particle distribution dominated by NCM811 was observed on the electrode fabricated in Comparative Example 6. On the electrode fabricated in Experimental Example 19, nano-sized LFMP particles were clearly observed to be uniformly coated on the surface of NCM811. Furthermore, the presence of Fe and P elements in the LFMP confirmed that the LFMP was uniformly distributed on the surface of NCM811.

[0194] Figure 16 shows a photograph of a nail penetration test conducted on a lithium battery based on Comparative Example 6. In this test, the lithium battery based on Comparative Example 6 was activated, aged, and capacity-tested before being charged to 100% capacity and subjected to a nail penetration test, resulting in fire and smoke.

[0195] Figure 17 shows a photograph of a nail penetration test conducted on a lithium battery based on Comparative Example 5. In this test, the lithium battery based on Comparative Example 5 was activated, aged, and capacity tested, and then charged to 100% capacity before being subjected to a nail penetration test. Although no fire occurred, smoke was still emitted.

[0196] As can be seen from the above, although Comparative Example 5, which has a smaller weight percentage of untreated LFMP powder, or Comparative Example 6, which has no added LFMP powder, has an electrode density similar to that of Experimental Examples 10-12, the nail penetration test results in Figures 16 and 17 show that lithium batteries made solely with the high-nickel cathode material NCM811 have a risk of catching fire, and adding insufficient amounts of untreated LFMP powder does not improve safety.

[0197] Figure 18 shows a photograph of a nail penetration test conducted on a lithium battery based on Experimental Example 18. In this test, the lithium battery based on Experimental Example 18 was activated, aged, and capacity tested before being charged to 100% capacity and subjected to a nail penetration test. No fire or smoke occurred, indicating that it was relatively safe.

[0198] The following experimental and test results, shown in Figures 19A to 22B, further illustrate the improved characteristics of the current collector of this application and the secondary battery made using the current collector. Figures 19A, 19B, 20A, and 20B are test results comparing the charge-discharge characteristics of secondary batteries of some embodiments of this application with those of different comparative examples. Figure 21 is a comparison of the tensile strength test results of secondary batteries of some embodiments of this application with those of comparative examples. Figures 22A and 22B are a comparison of the discharge test results of sodium-ion batteries made with the current collector of the embodiments of this application with those of comparative examples.

[0199] Please refer to Figures 19A and 19B first. Figure 19A shows the charge-discharge characteristics of a lithium battery (comparative example) with a cathode current collector made of ordinary aluminum foil, and Figure 19B shows the charge-discharge characteristics of a lithium battery (experimental example) with a cathode current collector made of the composite material described in Figure 4. In this embodiment, the composition of the cathode active material of the lithium battery is exemplified by containing LFMP (97.51%), LC2141 (0.49%), and PVDF (2.0%), but this application is not limited to this.

[0200] The charging conditions for the test were constant current and constant voltage charging at 0.1C and 4V until the 0.05C cutoff was achieved. The discharging conditions for the test were discharging at 2V using discharge rates of 0.1C, 1C, 2C, 3C, and 5C respectively.

[0201] The test results in Figures 19A and 19B clearly show that the lithium battery using composite material 400 exhibits superior discharge efficiency at different discharge rates (0.1C, 0.2C, 1C, 2C, 3C). For example, at 3C discharge, the secondary battery using composite material 400 still maintains a discharge efficiency of approximately 78%. In contrast, the lithium battery using ordinary aluminum foil already shows a discharge efficiency decrease to 78% at 1C discharge, and further decreases to 0% at 2C discharge.

[0202] In addition, it can be observed from Figures 19A and 19B that the lithium battery using composite material 400 has a significantly wider plateau region, and therefore has a better energy density compared to the lithium battery using ordinary aluminum foil.

[0203] Figure 20A shows the charge-discharge characteristics of a secondary battery (comparative example) with a cathode current collector typically coated with carbon black, and Figure 20B shows the charge-discharge characteristics of a secondary battery (experimental example) with a cathode current collector made using the aforementioned composite material. In the tests shown in Figures 20A and 20B, it is clearly evident that at different discharge rates, the secondary battery with the current collector made using the composite material 400 of this application maintains a relatively small voltage decay, meaning that compared to a secondary battery with a cathode current collector typically coated with carbon black, the secondary battery with the aforementioned composite material 400 exhibits better charge-discharge efficiency at high charge-discharge rates.

[0204] Figure 21 shows the tensile strength test results of a secondary battery with a cathode current collector made of the aforementioned composite material and a secondary battery with a cathode current collector made of ordinary aluminum foil. From the tensile characteristic curves CV1 (corresponding to the composite material) and CV2 (corresponding to ordinary aluminum foil) in Figure 21, it can be seen that composite material 400 can provide stronger mechanical stability and safety performance, resulting in secondary batteries made based on composite material 400 having better reliability and durability.

[0205] More specifically, under the test conditions of a cross-sectional area of ​​2.5 cm² and a tensile speed of 1 mm / min, the composite material of this application embodiment, when subjected to tensile strength testing, exhibits a tensile length exceeding that of a typical current collector without a nano-carbon layer (approximately 1.36 mm), reaching 1.42 mm; and a tensile strength of 91.4 N, which is also higher than that of a current collector without a nano-carbon layer (approximately 77.39 N).

[0206] A comparison of the discharge test results in Figures 22A and 22B shows that the sodium-ion battery experimental example made using the current collector of the present application has significantly better discharge efficiency and can maintain a relatively small voltage decay at different discharge rates.

[0207] This application is not limited to the embodiments described above, and various modifications can be made within the scope shown in the request. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included within the technical scope of this application. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0208] It should also be noted that any numerical values ​​mentioned in this application are not intended to limit the application to only the specified numerical values. Those skilled in the art will understand that there are permissible errors in each numerical value / composition ratio. As long as they do not significantly affect the results / functions to be achieved in each experimental example, any value that is similar to the disclosed numerical range is considered to be within the scope disclosed in this application.

[0209] Figure Label Explanation: 10: Lithium secondary battery; 11: Cathode; 110: Cathode material layer; 111: Cathode current collector; 12: Separator; 13: Anode; 130: Anode material layer; 131: Anode current collector; 200, 300, 400: Composite materials; 210, 310: Silicon particles; 220: Ceramic material; 230: Conductive carbon; 320: High entropy material; 410: Current collector substrate; 420: Nano-carbon layer; M1: Anode active material; M2: Conductive material; M3: Binder; NCT: Carbon nanotubes; S110~S140: Step flow of the preparation method of cathode active material; S210~S240, S310~S370: Step flow of the preparation method of anode active material; S410~S430: Step flow of the preparation method of lattice-stabilized material.

Claims

1. A current collector for a secondary battery, characterized in that, The current collector is made of a composite material, which includes a current collector substrate and a nano-carbon layer, wherein: The nano-carbon layer is formed and covers at least a portion of the surface of the current collector substrate, wherein the thickness of the nano-carbon layer is less than 1 micrometer (μm), and the mass percentage of carbon material in the nano-carbon layer is between 48% and 86%.

2. The current collector for a secondary battery as described in claim 1, characterized in that, The carbon material in the nano carbon layer accounts for between 60% and 66% of the total mass.

3. The current collector for a secondary battery as described in claim 1, characterized in that, The nano-carbon layer is formed on one or both surfaces of the current-collecting substrate.

4. The current collector for a secondary battery as described in claim 1, wherein when the composite material is subjected to tensile strength testing under test conditions of a cross-sectional area of ​​2.5 cm² and a tensile speed of 1 mm / min, the tensile length of the composite material exceeds 1.36 mm.

5. The current collector for a secondary battery as described in any one of claims 1 to 4, characterized in that, The composite material further includes a structural stabilizing material, wherein the structural stabilizing material is selected from at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), or polyacrylamide (PAM).

6. The current collector for a secondary battery as described in claim 5, wherein the weight ratio of the structurally stable material in the current collector is between 1% and 20%.

7. The current collector for a secondary battery according to any one of claims 1 to 4, characterized in that, The resistivity of the current collector is less than 30 Ω·cm.

8. A secondary battery, characterized in that, include: The cathode electrode includes a cathode material layer and a cathode current collector; The anode electrode includes an anode material layer and an anode current collector; as well as A diaphragm is disposed between the cathode electrode and the anode electrode; wherein at least one of the cathode current collector and the anode current collector is made of a first composite material, the first composite material comprising: One-channel substrate; and A nano-carbon layer covering at least a portion of the surface of the aluminum current collector substrate, the thickness of the nano-carbon layer being less than 1 μm, and the mass percentage of the nanomaterial in the nano-carbon layer being between 48% and 86%.

9. The secondary battery as described in claim 8, characterized in that, The carbon material accounts for between 60% and 66% of the mass of the carbon nanolayer.

10. The secondary battery as described in claim 9, characterized in that, The composite material further includes a structural stabilizing material, wherein the structural stabilizing material is selected from at least one of polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), carboxymethyl cellulose (CMC), polyvinyl alcohol (PVA), or polyacrylamide (PAM).

11. The secondary battery of claim 10, wherein the weight ratio of the structurally stable material in the current collector is between 1% and 20%.

12. The secondary battery according to any one of claims 8-11, characterized in that, When the secondary battery is discharged at a discharge rate of 3C or less, the discharge efficiency is not less than 78%.

13. The secondary battery as described in any one of claims 8-11, characterized in that, The cathode material layer is formed based on one or more cathode active materials, and the cathode active materials include a second composite material based on a high-nickel material, wherein the high-nickel material is a nickel-based electrochemical redox reaction center metal, and the molar ratio of nickel atoms in the high-nickel material exceeds 50%.

14. The secondary battery according to any one of claims 8-11, characterized in that, The anode material layer is formed based on one or more anode active materials, and the anode active materials include a third composite material formed of silicon particles and high-entropy materials, wherein the high-entropy materials are composed of at least five elements, and each element accounts for no more than 50% of the high-entropy materials.

15. The secondary battery as described in claim 14, characterized in that, In the third composite material, the high-entropy material is formed in at least one region on the surface of the silicon particles, and the chemical formula of the high-entropy material is Si1-(x+y+m+n+z)(M x N y A m B n X z )O p Where p = 0.1 to 2, M, N, A, and B are any one of the monovalent to tetravalent elements, and the valences of M, N, A, and B are all different; and X is a transition metal element or an element that is not monovalent to tetravalent.

16. The secondary battery as described in claim 13, characterized in that, The high-nickel material includes materials based on a lithium nickel oxide structure, and the lithium nickel oxide-based materials include lithium nickel cobalt aluminum oxide (LiNi). 1-x-y Co x Al y O2, NCA) and lithium nickel manganese cobalt oxide (LiNi 1-x- y Mn x Co y O2 (NMC) or LiNi 1-x-y Co x Mn y O2(NCM)) at least one of them.

17. The secondary battery as described in claim 13, characterized in that, The second composite material further includes a lattice-stabilizing material, wherein the lattice-stabilizing material is formed on at least a portion of the surface of the high-nickel material.

18. The secondary battery of claim 17, wherein the lattice stabilizing material is an LFMP slurry, and the LFMP slurry is generated using a dosage ratio conforming to the following range: in, A, B, C, D, and E represent the dosages of PVP, PVDF, phosphazene, NMP, and LFMP, respectively.

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