Composite negative plate, preparation method thereof and battery

Abstract

The invention relates to the technical field of secondary batteries, in particular to a composite negative plate, a preparation method thereof and a battery. The composite negative electrode plate comprises a current collector, a lithium metal layer and an inorganic metal oxide layer, wherein the lithium metal layer and the inorganic metal oxide layer are sequentially arranged on the surface of the current collector; wherein the material of the inorganic metal oxide layer comprises one or more of aluminum oxide and titanium oxide; and the surface of one side, deviating from the current collector, of the inorganic metal oxide layer is provided with a through micropore array structure. The composite negative plate provided by the invention not only can effectively buffer the volume fluctuation during lithium intercalation / deintercalation, but also can improve the lithium ion flux, so that the battery has higher cycling stability.

Description

Technical Field

[0001] This application relates to the field of secondary battery technology, specifically to composite negative electrode sheets and their preparation methods, and batteries. Background Technology

[0002] In the commercialization of lithium metal batteries, the performance and manufacturing process of the anode sheet are among the core limiting factors. Currently, lithium metal battery anode sheets are mainly made by mechanically rolling or bonding lithium metal foil with copper foil current collectors to obtain anode materials with high specific capacity.

[0003] However, this traditional negative electrode has the following problems in practical applications: (1) The solid electrolyte interphase (SEI) film generated during electrochemical cycling has defects such as insufficient uniformity and poor stability, which leads to high interfacial impedance and affects ion transport; and the film is prone to breakage during charge and discharge, which further aggravates the cycle decay of the battery. (2) Lithium metal will produce significant volume expansion during charge and discharge cycles, and its interface structure cannot effectively buffer the stress generated therefrom, which can easily cause damage to the electrode structure, which will also lead to capacity decay. Summary of the Invention

[0004] Based on this, this application provides a composite negative electrode sheet, its preparation method, and a battery. The composite negative electrode sheet provided by this application can not only effectively buffer volume fluctuations during lithium insertion / extraction, but also improve lithium-ion flux, giving the battery higher cycle stability.

[0005] A first aspect of this application provides a composite negative electrode sheet, comprising: a current collector and a lithium metal layer and an inorganic metal oxide layer sequentially disposed on the surface of the current collector;

[0006] The inorganic metal oxide layer is made of one or more of aluminum oxide and titanium oxide; the inorganic metal oxide layer has a through-hole array structure.

[0007] In some embodiments, the thickness of the inorganic metal oxide layer is 10 nm to 15 nm.

[0008] In some embodiments, the pore size of the micropores in the micropore array structure is 20µm to 40µm.

[0009] In some embodiments, on the side of the inorganic metal oxide layer facing away from the current collector, the total area of ​​the micropores in the micropore array structure accounts for 40% to 60%.

[0010] In some embodiments, the thickness of the current collector is 6µm to 20µm.

[0011] In some embodiments, the current collector is copper.

[0012] In some embodiments, the thickness of the lithium metal layer is 6µm to 20µm.

[0013] In some embodiments, the composite negative electrode further includes a perovskite layer disposed on the surface of the inorganic metal oxide layer opposite to the lithium metal layer.

[0014] The material of the perovskite layer includes CH3NH2SnX3, where X is one or more of Br and I.

[0015] The thickness of the perovskite layer is 100nm~150nm.

[0016] A second aspect of this application provides a method for preparing a composite negative electrode, comprising the following steps:

[0017] A lithium metal layer and an inorganic metal oxide layer are sequentially prepared on the surface of the current collector;

[0018] The inorganic metal oxide layer is opened by using the side surface facing away from the lithium metal layer as the opening surface, so that the inorganic metal oxide layer has a through-hole array structure.

[0019] The inorganic metal oxide layer is made of one or more of aluminum oxide and titanium oxide.

[0020] In some embodiments, after the step of preparing the inorganic metal oxide layer and before the step of performing the opening process, the method further includes:

[0021] Preparation of a perovskite layer on the surface of the inorganic metal oxide layer opposite to the lithium metal layer;

[0022] The material of the perovskite layer includes CH3NH2SnX3, where X is one or more of Br and I.

[0023] In some embodiments, the preparation steps of the perovskite layer include:

[0024] CH3NH2X and SnX2 are prepared according to the stoichiometric ratio of CH3NH2SnX3, and SnCl2 is added to obtain a mixture; wherein, the mass fraction of SnCl2 in the mixture is 4%~7%;

[0025] The mixture is ball-milled, annealed, and pressed into shape to prepare the target material.

[0026] The perovskite layer is prepared using the target material as the target material and a radio frequency magnetron sputtering process.

[0027] In some embodiments, the process parameters of the ball mill include: a rotation speed of 300 rpm to 600 rpm, a temperature of 20°C to 35°C, and a humidity of 20% to 30%.

[0028] In some embodiments, the annealing step includes: a first annealing treatment at 75°C to 85°C for 1 hour to 3 hours, a second annealing treatment at 180°C to 220°C for 1 hour to 3 hours, and a third annealing treatment at 290°C to 310°C for 10 hours to 14 hours.

[0029] In some embodiments, the process parameters for compression molding include: a compression pressure of 100 to 200 tons and a compression time of 3 to 10 minutes.

[0030] In some embodiments, the process parameters for preparing the perovskite layer using radio frequency magnetron sputtering include: power of 80W~120W, argon flow rate of 15sccm~25sccm, pressure of 0.8Pa~1.2Pa, and substrate temperature of 40℃~70℃.

[0031] In some embodiments, the opening process includes: using the surface of the perovskite layer facing away from the inorganic metal oxide layer as the opening surface for opening, so that both the perovskite layer and the inorganic metal oxide layer have a through-hole array structure.

[0032] In some embodiments, after the pore-opening step, the method further includes filling the micropore array structure in the perovskite layer with CH3NH2X and / or methylamine to prepare the composite negative electrode.

[0033] In some embodiments, the step of filling the microporous array structure in the perovskite layer includes:

[0034] Under conditions of pressure of 10Pa~50Pa and temperature of 80℃~120℃, CH3NH2X gas is introduced at a flow rate of 5sccm~10sccm for the first filling treatment, and then methylamine gas and CH3NH2X gas with a volume ratio of 1:(3~5) are introduced for the second filling treatment.

[0035] In some embodiments, the preparation step of the lithium metal layer includes: under a vacuum degree ≤1×10 -3 The lithium metal layer was prepared by vacuum evaporation at a deposition rate of 0.1 nm / s to 1 nm / s under the condition of Pa.

[0036] In some embodiments, prior to the step of preparing the lithium metal layer on the current collector surface, the method further includes:

[0037] The current collector is placed under a vacuum degree ≤5×10-3 Pa, ion bombardment energy 500 eV~1000 eV, ion beam current density 0.1 mA / cm² 2 ~0.3mA / cm 2 Argon ion beam bombardment was performed under these conditions.

[0038] In some embodiments, the inorganic metal oxide layer is prepared by magnetron sputtering.

[0039] The inorganic metal oxide layer is made of aluminum oxide, and the preparation steps of the inorganic metal oxide layer include: using aluminum as a target material, depositing the inorganic metal oxide layer on the surface of the lithium metal layer under the conditions of magnetron sputtering power of 50W~90W, argon flow rate of 15sccm~25sccm, substrate temperature of 50℃~70℃, and oxygen flow rate of 5sccm~10sccm.

[0040] In some embodiments, the inorganic metal oxide layer is made of titanium oxide, and the preparation steps of the inorganic metal oxide layer include: using titanium oxide as a target, depositing the inorganic metal oxide layer on the surface of the lithium metal layer under the conditions of magnetron sputtering power of 60W~100W, argon flow rate of 12sccm~20sccm, and substrate temperature of 50℃~80℃.

[0041] A third aspect of this application provides a battery comprising the composite negative electrode sheet described in the first aspect of this application, or a composite negative electrode sheet prepared by the preparation method of the second aspect.

[0042] The composite negative electrode sheet provided in this application has at least the following beneficial effects:

[0043] The composite negative electrode provided in this application uses a current collector as the substrate, and the lithium metal layer disposed on it can provide active materials for lithium-ion insertion / extraction during the battery charging and discharging process. Further, alumina and titanium oxide with microporous array structures are selected as inorganic metal oxide layers. Alumina has low reactivity with lithium metal and electrolyte, and can construct a stable rigid chemical barrier to effectively suppress lithium dendrite puncture. Titanium oxide has good reversibility of lithium-ion insertion / extraction, which can buffer volume fluctuations during charging and discharging. Simultaneously, the microporous array structures of alumina and titanium oxide can guide lithium ions to deposit evenly along the surface rather than vertically during electrochemical cycling, thus suppressing lithium dendrite formation. They can also increase lithium-ion flux, alleviate stress expansion, and thereby extend the battery's cycle life.

[0044] Therefore, the composite negative electrode provided in this application can not only effectively buffer the volume fluctuations during lithium insertion / extraction, but also improve the lithium-ion flux, giving the battery higher cycle stability. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a schematic diagram of the structure of a composite negative electrode provided as an example in this application;

[0047] Figure 2 A schematic diagram of the structure of a composite negative electrode provided as another example of this application.

[0048] Explanation of reference numerals in the attached figures

[0049] 10. Composite negative electrode; 100. Current collector; 200. Lithium metal layer; 300. Inorganic metal oxide layer; 400. Perovskite layer. Detailed Implementation

[0050] The composite negative electrode sheet, its preparation method, and the battery of this application are further described in detail below with reference to specific embodiments. This application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0051] Currently, lithium metal battery anodes are mainly composed of lithium metal foil and current collectors. However, during electrochemical cycling, the thickness and morphology of lithium deposition are difficult to control uniformly. Excessively high local current density can promote the preferential formation of dendrites, which can pierce the separator, disrupt the battery's chemical balance, and accelerate cycle degradation. Secondly, traditional SEI films are not uniformly formed and have poor stability, resulting in high interfacial impedance and easy breakage during charge and discharge, further aggravating cycle degradation. In addition, lithium metal expands significantly during charge and discharge cycles, and the interfacial structure of traditional anode sheets cannot effectively buffer stress, leading to electrode structure damage and capacity decay.

[0052] In addition, some studies have explored the fabrication of artificial SEIs or surface functional layers on the surface of traditional anode sheets. However, the fabrication processes for artificial SEIs or surface functional layers in traditional technologies typically rely on multi-step chemical deposition, high-temperature treatment, and dehydration processes. These processes are complex, energy-intensive, and difficult to scale up for continuous production, thus hindering the large-scale use of lithium metal batteries. Therefore, there is an urgent need for a composite anode sheet that can reduce capacity decay and has a simple fabrication process.

[0053] See Figure 1In a first aspect, this application provides a composite negative electrode 10, comprising: a current collector 100 and a lithium metal layer 200 and an inorganic metal oxide layer 300 sequentially disposed on the surface of the current collector 100.

[0054] The inorganic metal oxide layer 300 is made of one or more materials, including aluminum oxide and titanium oxide. The surface of the inorganic metal oxide layer 300 facing away from the current collector 100 has a through-hole array structure.

[0055] See Figure 2 In some examples, the composite negative electrode further includes a perovskite layer 400 disposed on the surface of the inorganic metal oxide layer facing away from the lithium metal layer. The material of the perovskite layer 400 includes CH3NH2SnX3, where X is one or more of Br and I. In this case, the composite negative electrode 10 includes: a current collector 100 and a lithium metal layer 200, an inorganic metal oxide layer 300, and a perovskite layer 400 sequentially disposed on the surface of the current collector 100. The surface of the inorganic metal oxide layer 300 facing away from the current collector 100 has a through-hole microporous array structure.

[0056] The composite negative electrode provided in this application uses a current collector as the substrate, and the lithium metal layer disposed on it can provide active material for lithium-ion insertion / extraction during battery charging and discharging. Furthermore, alumina and titanium oxide, which have microporous array structures, are selected as the inorganic metal oxide layers. Alumina has low reactivity with lithium metal and electrolyte, and can construct a stable rigid chemical barrier to effectively suppress lithium dendrite penetration. Titanium oxide has good reversibility of lithium-ion insertion / extraction, and can buffer volume fluctuations during charging and discharging. Moreover, this application found that when titanium oxide is used as the inorganic metal oxide layer, its band gap is 3.0~3.2 eV, achieving a balance between electronic insulation and ion conduction. Its surface easily forms stable Li-O bonds, thereby promoting a tight bond between the inorganic metal oxide layer and the lithium metal layer and reducing interfacial impedance.

[0057] Furthermore, alumina and titanium dioxide, with their microporous array structures, can guide lithium ions to deposit in a flat, non-vertical manner during electrochemical cycling, thus suppressing lithium dendrite formation. They can also increase lithium ion flux and alleviate stress expansion. Specifically, during the initial charge-discharge cycle, lithium metal loses electrons and exits through the pores of the inorganic metal oxide. After the first cycle, lithium ions gain electrons and preferentially deposit on the exposed lithium metal surface at the pores, while some lithium metal also deposits between the lithium metal layer and the inorganic metal oxide layer. The high mechanical strength of the inorganic metal oxide layer protects the perovskite layer, preventing its damage. Once the pores are filled, due to the low surface contact energy between the inorganic metal oxide and lithium metal, and the high resistance of the inorganic metal oxide layer restricting the electron channels, the inorganic metal oxide begins to guide lithium ion deposition. This causes the subsequent lithium metal to grow laterally rather than vertically in a pointed manner on both the upper and lower surfaces of the inorganic metal oxide layer (between the inorganic metal oxide layer and the lithium metal layer, and between the inorganic metal oxide layer and the perovskite layer). This improves the initial nucleation uniformity of lithium ions and suppresses the formation of lithium dendrites.

[0058] The perovskite layer possesses high ionic conductivity and a flexible lattice structure, providing continuous and low-resistance diffusion channels for lithium ions during deposition and buffering lithium volume changes. Simultaneously, the organic components in the perovskite layer improve the interfacial hydrophilicity, allowing the electrolyte to spread rapidly and uniformly wet the pore structure, ensuring stable ion transport across the entire interface. This excellent wettability effectively reduces interfacial contact resistance, preventing excessively high local current densities and further promoting uniform lithium ion deposition. Therefore, the composite negative electrode provided in this application not only effectively buffers volume fluctuations during lithium insertion / extraction but also increases lithium-ion flux, resulting in higher cycle stability of the battery.

[0059] In some examples, the thickness of the current collector is 6µm to 20µm. For example, the thickness of the current collector includes, but is not limited to, 6µm, 8µm, 10µm, 12µm, 14µm, 16µm, 18µm, or 2µm, or any two of these values ​​as endpoints. The current collector provides conductivity and mechanical support for the composite negative electrode. Setting the thickness of the current collector within the above range allows it to have a tensile strength of ≥200MPa, while preventing deformation during winding and loss of battery energy density due to excessively thick current collectors.

[0060] In some of these examples, the current collector is copper.

[0061] In some examples, the thickness of the lithium metal layer is 6µm to 20µm. The thickness of the lithium metal layer includes, but is not limited to, 6µm, 8µm, 10µm, 12µm, 15µm, 18µm, or 20µm, or any two of these values ​​as endpoints. A lithium metal layer thickness within these ranges provides sufficient active material for lithium-ion insertion / extraction during battery charging and discharging.

[0062] In some examples, the thickness of the inorganic metal oxide layer is 10 nm to 15 nm. The thickness of the inorganic metal oxide layer includes, but is not limited to, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm, or 15 nm, or any two of these values ​​as endpoints. Inorganic metal oxide layers within this thickness range ensure continuous film coverage, preventing the lithium metal layer from being exposed and allowing it to adhere to the lithium metal layer surface via chemical bonds, thus avoiding interlayer delamination during the fabrication of the microporous array structure. Simultaneously, this thickness range also avoids the high sheet resistance caused by slightly thicker layers, preventing negative impacts on the battery's electrochemical performance.

[0063] In some examples, the inorganic metal oxide layer is an alumina layer. The alumina layer can adhere to the lithium metal layer surface through chemical bonds, avoiding interlayer delamination during the fabrication of the microporous array structure. Furthermore, alumina has low reactivity with lithium metal and the electrolyte, thus forming a stable chemical barrier. Its high mechanical strength, such as an elastic modulus of 380 GPa, also effectively suppresses lithium dendrite penetration.

[0064] In other examples, the inorganic metal oxide layer is a titanium oxide layer. The interaction between the titanium oxide layer and the current collector is mainly van der Waals forces, supplemented by chemisorption, which also ensures interfacial stability. Furthermore, titanium oxide exhibits good reversibility of lithium-ion insertion / extraction, such as a lithium-ion diffusion coefficient of 10. -9 cm 2 / s~10 -8 cm 2 / s, which can buffer volume fluctuations during lithium deposition / stripping.

[0065] Understandably, the inorganic metal oxide layer has a through-hole microporous array structure, so the pore depth of the microporous array structure is consistent with the thickness of the inorganic metal oxide layer.

[0066] In some examples, the pore size of the micropores in the micropore array structure is 20µm to 40µm. For example, the pore size includes, but is not limited to, 20µm, 22µm, 24µm, 26µm, 28µm, 30µm, 32µm, 34µm, 36µm, 38µm, or 40µm, or any two of the above values ​​as endpoints. More preferably, the pore size of the micropores in the micropore array structure is 28µm to 32µm.

[0067] In some of these examples, on the side of the inorganic metal oxide layer facing away from the current collector, the total area of ​​the micropores in the micropore array structure accounts for 40% to 60%.

[0068] In this application, the percentage of "the total area of ​​micropores in the micropore array structure to the surface area of ​​the inorganic oxide" is the porosity. For example, the percentage of the total area of ​​micropores in the micropore array structure to the surface area of ​​the inorganic oxide includes, but is not limited to, 40%, 42%, 45%, 47%, 49%, 50%, 52%, 55%, 58%, or 60%, or any two of the above values ​​as endpoints.

[0069] The pore depth, pore size, and porosity of the microporous array structure work synergistically, providing the inorganic metal oxide layer with sufficient mechanical strength to prevent lithium dendrite penetration while inducing uniform lithium deposition. Furthermore, the microporous array structure provides suitable channels for lithium-ion transport, enhancing lithium-ion transport efficiency. Therefore, the aforementioned microporous array structure improves battery energy density while simultaneously controlling cost and extending cycle life.

[0070] In some examples, the thickness of the perovskite layer is 100 nm to 150 nm. For example, the thickness of the perovskite layer includes, but is not limited to, 100 nm, 105 nm, 110 nm, 115 nm, 120 nm, 125 nm, 130 nm, 135 nm, 140 nm, 145 nm or 150 nm, or any two of the above values ​​as endpoints.

[0071] CH3NH2SnX3 was selected as the material for the perovskite layer. This application discovered that the organic component CH3NH2... + It can enhance wettability with electrolytes, and the inorganic component SnX3 - It can bond tightly to the interface of inorganic metal oxide layers. At the same time, this perovskite material possesses high lithium-ion conductivity.

[0072] Understandably, the microporous array structure on the side of the inorganic metal oxide layer facing away from the current collector is formed after the perovskite layer is prepared, by performing an opening process on the surface of the perovskite layer as the opening surface. At this time, both the perovskite layer and the inorganic metal oxide layer have microporous array structures. Subsequently, the microporous array structure of the perovskite layer is filled with methylamine gas and CH3NH2X gas. Since SnCl2 is added in the step of preparing the perovskite layer by magnetron sputtering, methylamine, CH3NH2X and Sn can form CH3NH2SnX3 material, so the microporous array structure in the perovskite layer is filled, and there is no obvious interface boundary after filling. At this time, the perovskite layer does not have a microporous array structure.

[0073] A second aspect of this application provides a method for preparing a composite negative electrode, comprising the following steps:

[0074] S11: A lithium metal layer and an inorganic metal oxide layer are sequentially prepared on the surface of the current collector.

[0075] S12: The inorganic metal oxide layer is opened by using the side of the inorganic metal oxide layer facing away from the lithium metal layer as the opening surface, so that the inorganic metal oxide layer has a through micropore array structure.

[0076] The inorganic metal oxide layer is made of one or more of aluminum oxide and titanium oxide.

[0077] In some examples, after the step of preparing the inorganic metal oxide layer and before the step of performing the opening process, the process further includes:

[0078] A perovskite layer is prepared on the surface of the inorganic metal oxide layer facing away from the lithium metal layer. The material of the perovskite layer includes CH3NH2SnX3, where X is one or more of Br and I. Step S11 is then:

[0079] S11: A lithium metal layer, an inorganic metal oxide layer, and a perovskite layer are sequentially prepared on the surface of the current collector.

[0080] Understandably, the materials and thicknesses of the current collector, the lithium metal layer, the inorganic metal oxide layer, and the perovskite layer are the same as those in the first aspect of this application, so they will not be repeated here.

[0081] In some of these examples, prior to the step of preparing a lithium metal layer on the current collector surface, the following steps are also included:

[0082] S10: Place the current collector under a vacuum degree ≤5×10 -3 Pa, ion bombardment energy 500 eV~1000 eV, ion beam current density 0.1 mA / cm² 2 ~0.3mA / cm 2 Argon ion beam bombardment was performed under these conditions.

[0083] This application discovers that bombarding the surface of the current collector with an argon ion beam before the lithium metal layer preparation step can increase the surface roughness of the current collector, increase the number of surface active sites, and form an uneven anchoring structure. This provides mechanical locking for the subsequent lithium metal layer preparation and enhances interfacial adhesion. Taking copper foil as the negative electrode current collector as an example, tests show that the surface roughness of the copper foil before argon ion beam bombardment is approximately 50 nm, and approximately 100 nm before argon ion beam bombardment.

[0084] For example, in step S10, the vacuum degree of the argon ion beam bombardment treatment is 1×10⁻⁶.-3 Pa~5×10 -3 Pa. Furthermore, the vacuum level of the argon ion beam bombardment treatment includes, but is not limited to, 1 × 10⁻⁶. -3 Pa, 2×10 -3 Pa, 3×10 -3 Pa, 4×10 -3 Pa or 5×10 -3 Pa, or any two of the above point values ​​as endpoints, within a range. This vacuum condition can reduce the scattering interference of gas molecules on the argon ion beam, ensuring that the bombardment energy acts stably and uniformly on the current collector surface, thereby effectively improving surface cleanliness and activation of active sites.

[0085] For example, in step S10, the ion bombardment energy includes, but is not limited to, 500 eV, 550 eV, 600 eV, 650 eV, 700 eV, 750 eV, 800 eV, 850 eV, 900 eV, 950 eV, or 1000 eV, or any two of the above values ​​as endpoints. Within the above range, the ion bombardment energy can effectively remove surface contaminants and introduce appropriate roughness to activate the surface, while avoiding damage to the current collector substrate caused by excessively high energy.

[0086] For example, in step S10, the ion beam current density includes, but is not limited to, 0.1 mA / cm². 2 0.15mA / cm 2 0.2mA / cm 2 0.25mA / cm 2 Or 0.3 mA / cm 2 The current density is within the range defined by any two of the above point values ​​as endpoints. This current density ensures sufficient bombardment intensity to achieve surface cleaning and activation, while avoiding localized overheating or excessive surface etching caused by excessive current.

[0087] In some examples, in step S10, the argon ion beam bombardment time is 60s to 180s. For example, the argon ion beam bombardment time includes, but is not limited to, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 140s, 160s, or 180s, or any two of the above point values ​​as endpoints.

[0088] In some of these examples, step S11, the preparation of the lithium metal layer includes: under a vacuum degree ≤1×10 -3 Lithium metal layers were prepared by vacuum evaporation at deposition rates of 0.1 nm / s to 1 nm / s under vacuum conditions. The vacuum level included, but was not limited to, 0.5 × 10⁻⁶ Pa. -3 Pa, 0.6×10 -3 Pa, 0.7×10-3 Pa, 0.8×10 -3 Pa, 0.9×10 -3 Pa or 1×10 -3 Pa, or any two of the above point values ​​as endpoints. The deposition rate includes, but is not limited to, 0.1 nm / s, 0.2 nm / s, 0.3 nm / s, 0.5 nm / s, 0.7 nm / s, 0.9 nm / s or 1 nm / s, or any two of the above point values ​​as endpoints.

[0089] The lithium metal layer prepared under the above conditions ensures sufficient surface diffusion time for lithium atoms, enabling uniform and dense deposition of the lithium metal layer. Simultaneously, the above method for preparing the lithium metal layer also maintains high production efficiency.

[0090] In some examples, after the lithium metal layer preparation step S11, the process further includes holding the lithium metal layer under vacuum for 20 to 30 minutes. Understandably, the pressure used for this holding is the same as that used in the vacuum evaporation method for preparing the lithium metal layer. Further holding the lithium metal layer under vacuum for 20 to 30 minutes allows for sufficient fusion of the lithium metal layer with the current collector and relaxation of internal stress, thereby obtaining a dense, firmly adhered, and cycle-stable lithium metal layer. For example, the holding time may include, but is not limited to, 20 minutes, 23 minutes, 25 minutes, 27 minutes, 29 minutes, or 30 minutes, or any two of the above values ​​as endpoints.

[0091] In some of these examples, the thickness of the lithium metal layer is 5µm to 20µm. The thickness of the lithium metal layer includes, but is not limited to, 5µm, 6µm, 8µm, 9µm, 10µm, 12µm, 13µm, 14µm, 15µm, 18µm or 20µm, or any two of the above values ​​as endpoints.

[0092] In some of these examples, in step S11, the inorganic metal oxide layer is prepared by magnetron sputtering.

[0093] In some examples, in step S11, the material of the inorganic metal oxide layer includes aluminum oxide. The preparation step of the inorganic metal oxide layer includes: using aluminum as a target, depositing an inorganic metal oxide layer on the surface of a lithium metal layer under the conditions of magnetron sputtering power of 50W~90W, argon flow rate of 15sccm~25sccm, substrate temperature of 50℃~70℃, and oxygen flow rate of 5sccm~10sccm. In this example, the magnetron sputtering power includes, but is not limited to, 50W, 55W, 60W, 65W, 70W, 75W, 80W, 85W, or 90W, or any two of the above values ​​as endpoints. The argon flow rate includes, but is not limited to, 15sccm, 18sccm, 20sccm, 22sccm, or 25sccm, or any two of the above values ​​as endpoints. The substrate temperature includes, but is not limited to, 50℃, 55℃, 60℃, 65℃, or 70℃, or any two of the above values ​​as endpoints. Oxygen flow rates include, but are not limited to, 5 sccm, 6 sccm, 7 sccm, 8 sccm, 9 sccm, or 10 sccm, or a range formed by two of the above point values ​​as endpoints. In this example, the base temperature is the current collector temperature.

[0094] This preparation method can produce a dense alumina layer. The chemical bonds in the alumina layer can be firmly attached to the surface of the lithium metal layer, which not only avoids interlayer delamination during subsequent pore opening and battery cycling, but also provides a stable mechanical substrate for lithium deposition.

[0095] In some examples, alumina is prepared by magnetron sputtering using a roll-to-roll production line. In this case, the transport rate of the alumina intermediate to be prepared is 1.5 m / min to 3 m / min. For example, the transport rate of the alumina intermediate to be prepared includes, but is not limited to, 1.5 m / min, 1.8 m / min, 2 m / min, 2.2 m / min, 2.5 m / min, 2.8 m / min, or 3 m / min.

[0096] In some examples, the inorganic metal oxide layer is made of titanium oxide. The preparation steps of the inorganic metal oxide layer include: using titanium oxide as a target, depositing the inorganic metal oxide layer on the surface of the lithium metal layer under conditions of magnetron sputtering power of 60W~100W, argon flow rate of 12sccm~20sccm, and substrate temperature of 50℃~80℃. In this example, the magnetron sputtering power includes, but is not limited to, 60W, 65W, 70W, 75W, 80W, 85W, 90W, 95W, or 100W, or any two of the above values ​​as endpoints. The argon flow rate includes, but is not limited to, 12sccm, 15sccm, 18sccm, or 20sccm, or any two of the above values ​​as endpoints. The substrate temperature includes, but is not limited to, 50℃, 55℃, 60℃, 65℃, 70℃, 72℃, 75℃, 78℃, or 80℃, or any two of the above values ​​as endpoints. In this example, the substrate temperature is the current collector temperature. In this example, the deposition rate of titanium oxide is 0.8 nm / min to 2 nm / min. The deposition rate of titanium oxide includes, but is not limited to, 0.8 nm / min, 1 nm / min, 1.2 nm / min, 1.5 nm / min, 1.8 nm / min or 2 nm / min.

[0097] The preparation parameters of titanium oxide within the above range can ensure that the titanium oxide layer is continuous and dense, and has good bonding with the current collector substrate.

[0098] In some examples, titanium oxide is prepared by magnetron sputtering using a roll-to-roll production line. In this case, the transport rate of the titanium oxide intermediate to be prepared is 2 m / min to 4 m / min. For example, the transport rate of the titanium oxide intermediate to be prepared includes, but is not limited to, 2 m / min, 2.5 m / min, 3 m / min, 3.5 m / min, or 4 m / min.

[0099] In some of these examples, the steps for preparing the perovskite layer include:

[0100] a. Prepare CH3NH2X and SnX2 according to the stoichiometric ratio of CH3NH2SnX3, and then add SnCl2 to obtain a mixture.

[0101] b. After ball milling, annealing, and pressing the mixture into shape, target material is prepared.

[0102] c. Using target material as the target, a perovskite layer is prepared by radio frequency magnetron sputtering.

[0103] CH3NH2SnX3 was selected as the material for the perovskite layer. This application discovered that the organic component CH3NH2... + It can enhance wettability with electrolytes, and the inorganic component SnX3 -It can bond tightly to the interface of inorganic metal oxide layers. Furthermore, the high lithium-ion conductivity of this perovskite material, combined with magnetron sputtering technology, ensures the uniformity and stability of the perovskite layer preparation.

[0104] In some examples, in step a, the mass fraction of SnCl2 in the mixture is 4% to 7%. Adding SnCl2 to the mixture, and limiting its mass fraction to the above range, prevents the oxidation of tin ions. For example, the mass fraction of SnCl2 in the mixture includes, but is not limited to, 4.5%, 5%, 5.5%, 6%, 6.5%, or 7%, or any two of the above values ​​as endpoints.

[0105] Understandably, in step a, the molar ratio of CH3NH2X to SnX2 is 1:1.

[0106] In some examples, step b includes the following process parameters for ball milling: rotation speed of 300 rpm to 600 rpm, temperature of 20°C to 35°C, and humidity of 20% to 30%. Ball milling under these conditions provides reaction energy through impact and friction, achieving uniform particle size reduction and thorough mixing of materials, while avoiding structural damage or performance degradation caused by high temperature and humidity. For example, the rotation speed of the ball mill includes, but is not limited to, 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm, or 600 rpm, or any two of these values ​​as endpoints. The temperature includes, but is not limited to, 20°C, 22°C, 25°C, 28°C, 30°C, or 35°C, or any two of these values ​​as endpoints. The humidity includes, but is not limited to, 20%, 22%, 25%, 28%, or 30%, or any two of these values ​​as endpoints.

[0107] In some examples, step b, the annealing process includes: a first annealing treatment at 75°C to 85°C for 1 hour to 3 hours, a second annealing treatment at 180°C to 220°C for 1 hour to 3 hours, and a third annealing treatment at 290°C to 310°C for 10 hours to 14 hours. Step annealing at the above temperatures improves the crystallinity of the material. The temperature of the first annealing treatment includes, but is not limited to, 75°C, 78°C, 80°C, 82°C, or 85°C. The duration of the first annealing treatment includes, but is not limited to, 1 hour, 2 hours, or 3 hours. The temperature of the second annealing treatment includes, but is not limited to, 180°C, 182°C, 185°C, 190°C, 200°C, 210°C, or 220°C. The duration of the second annealing treatment includes, but is not limited to, 1 hour, 2 hours, or 3 hours. The temperature of the third annealing treatment includes, but is not limited to, 290°C, 295°C, 298°C, 300°C, 305°C, or 310°C. The time for the third annealing process includes, but is not limited to, 10 hours, 12 hours, or 14 hours.

[0108] In some examples, step b includes the following process parameters for pressing: pressing pressure of 100 to 200 tons and pressing time of 3 to 10 minutes. Pressing under these parameters further increases the density of the target material, making it >95%. Furthermore, the pressed target material has a smooth surface and a metallic luster, indicating high density and tight particle bonding, which reduces particle contamination during sputtering and ensures uniform film deposition and performance stability. For example, pressing pressures include, but are not limited to, 100 tons, 120 tons, 140 tons, 160 tons, 180 tons, or 200 tons. Pressing times include, but are not limited to, 3 minutes, 5 minutes, 8 minutes, or 10 minutes.

[0109] In some examples, in step c, the process parameters for preparing the perovskite layer using radio frequency magnetron sputtering include: power of 80W~120W, argon flow rate of 15sccm~25sccm, pressure of 0.8Pa~1.2Pa, and substrate temperature of 40℃~70℃. It can be understood that the above substrate temperature is the temperature of the intermediate perovskite layer to be prepared. In step c, the power includes, but is not limited to, 80W, 85W, 90W, 95W, 100W, 105W, 110W, 115W, or 120W. The argon flow rate includes, but is not limited to, 15sccm, 18sccm, 20sccm, 22sccm, or 25sccm. The pressure includes, but is not limited to, 0.8Pa, 0.9Pa, 1Pa, or 1.2Pa. The substrate temperature includes, but is not limited to, 40℃, 42℃, 43℃, 45℃, 47℃, 50℃, 55℃, 58℃, 60℃, 65℃, or 70℃. The perovskite layer prepared by the radio frequency magnetron sputtering process using the above parameters is dense.

[0110] In some examples, perovskite layers are prepared by radio frequency magnetron sputtering using a roll-to-roll production line. In this case, the transport rate of the intermediate perovskite layer to be prepared is 0.6 m / min to 1.2 m / min. For example, the transport rate of the intermediate titanium oxide to be prepared includes, but is not limited to, 0.6 m / min, 0.8 m / min, 1 m / min, or 1.2 m / min.

[0111] In some examples, the opening process includes: using the surface of the perovskite layer facing away from the inorganic metal oxide layer as the opening surface, so that both the perovskite layer and the inorganic metal oxide layer have a through-hole array structure.

[0112] In some of these examples, the following steps after the opening process include:

[0113] S13: The composite negative electrode is prepared by filling the microporous array structure in the perovskite layer with CH3NH2X and / or methylamine.

[0114] Understandably, the equipment used for opening holes includes, but is not limited to, laser drilling equipment or ultrasonic drilling equipment. Any equipment that can ensure the micropore depth, micropore diameter, and opening ratio in the micropore array structure meet the requirements of the first aspect of this application is acceptable. This application performs opening hole processing on the surface of a metal oxide layer, which enables the metal oxide layer to possess both high mechanical strength and excellent lithium-ion transport performance.

[0115] In some examples, step S13, which involves filling the microporous array structure in the perovskite layer, includes:

[0116] Under conditions of pressure of 10 Pa to 50 Pa and temperature of 80 °C to 120 °C, CH3NH2X gas is introduced at a flow rate of 5 sccm to 10 sccm for the first filling treatment, followed by a second filling treatment of methylamine gas and CH3NH2X gas in a volume ratio of 1:(3 to 5). Pressures include, but are not limited to, 10 Pa, 20 Pa, 30 Pa, 40 Pa, or 50 Pa. Temperatures include, but are not limited to, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, or 120 °C. The flow rate of CH3NH2X gas includes, but is not limited to, 5 sccm, 8 sccm, or 10 sccm. The volume ratio of methylamine gas to CH3NH2X gas includes, but is not limited to, 1:3, 1:3.5, 1:4, 1:4.5, or 1:5.

[0117] Understandably, the difference between the first filling process and the second filling process lies in the different gases used. The pressure and temperature of the second filling process are the same as those of the first filling process. Reaction apparatuses providing pressures of 10 Pa to 50 Pa and temperatures of 80°C to 120°C include, but are not limited to, vacuum reaction chambers.

[0118] Furthermore, the first filling process takes 10 to 15 minutes. The second filling process takes 8 to 12 minutes.

[0119] In this step, CH3NH2X gas is first used for initial filling. CH3NH2X gas has good diffusivity; under the aforementioned pressure and temperature, it can penetrate the inner walls and depths of the micropores through molecular polarity adsorption, forming an initial adsorption layer on the inner walls and deep within the micropores via van der Waals forces. With continuous gas introduction, gas molecules gradually accumulate on the surface of the initial adsorption layer and bind together through intermolecular forces. Subsequently, methylamine and CH3NH2X gas are introduced in a volume ratio of 1:(3~5). Methylamine molecules can regulate the orientation of CH3NH2X, promoting its orderly radial growth along the micropores, extending gradually from the inner wall towards the center, ultimately forming a continuous and dense filling structure. During this process, methylamine gas also suppresses the formation of secondary pores within the filling layer, achieving dense filling of the micropores. Furthermore, methylamine and CH3NH2X gas synergistically interact with excess SnCl2 in magnetron sputtering to generate CH3NH2SnX3 within the pores. Observations show that it is tightly bonded to the perovskite layer with no interfacial cracks, thus achieving efficient pore closure.

[0120] The preparation method provided in this application uses a current collector as a substrate and prepares a lithium metal layer by vapor deposition. The lithium metal layer serves as the lithium source for the battery active material. An inorganic metal oxide layer is prepared on the surface of the lithium metal layer using magnetron sputtering. After pore opening treatment, a microporous array structure is formed. The rigid structure of the inorganic metal oxide layer, combined with the microporous array structure, can both prevent lithium dendrite penetration and achieve efficient lithium ion transport. Finally, CH3NH2SnX3 is prepared by magnetron sputtering as the perovskite layer, in which the organic component CH3NH2... + It can enhance wettability with electrolytes, and the inorganic component SnX3 - It can bond tightly to the interface of inorganic metal oxide layers. Simultaneously, the high lithium-ion conductivity of this perovskite material, combined with magnetron sputtering, ensures the uniformity and stability of the perovskite layer preparation. Therefore, the preparation method of this application can produce a negative electrode sheet that effectively mitigates battery structural damage and delays battery capacity decay. Furthermore, the above preparation method does not require high-temperature treatment or dehydration treatment; it can perform evaporation, magnetron sputtering, etc. sequentially through a roll-to-roll production line. Its preparation process is simple, easily achievable through continuous production, and conducive to the large-scale commercial use of lithium metal batteries.

[0121] Understandably, the second aspect of this application provides two preparation methods. In some of these examples, the preparation steps of the composite negative electrode include:

[0122] S11: A lithium metal layer and an inorganic metal oxide layer are sequentially prepared on the surface of the current collector.

[0123] S12: The inorganic metal oxide layer is opened by using the side of the inorganic metal oxide layer facing away from the lithium metal layer as the opening surface, so that the inorganic metal oxide layer has a through micropore array structure.

[0124] In other examples, the preparation steps of the composite negative electrode include:

[0125] S11: A lithium metal layer, an inorganic metal oxide layer, and a perovskite layer are sequentially prepared on the surface of the current collector.

[0126] S12: The perovskite layer is opened on the side facing away from the inorganic metal oxide layer, so that both the perovskite layer and the inorganic metal oxide layer have a through-hole array structure.

[0127] S13: The microporous array structure in the perovskite layer is filled with CH3NH2X and / or methylamine to prepare a composite negative electrode. A third aspect of this application provides a battery comprising the composite negative electrode of the first aspect of this application, or a composite negative electrode prepared by the method of the second aspect.

[0128] In some of these examples, the battery is a lithium metal battery.

[0129] The following detailed embodiments illustrate this application in more detail. It should also be understood that the following embodiments are for further explanation only and should not be construed as limiting the scope of protection of this application. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of this application fall within the scope of protection of this application. The specific process parameters, etc., in the following embodiments are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not necessarily limited to the specific values ​​in the embodiments below.

[0130] Example 1

[0131] Composite negative electrode sheet: includes a current collector and a lithium metal layer, an inorganic metal oxide layer and a perovskite layer sequentially disposed on the surface of the current collector; and the inorganic metal oxide layer has a microporous array structure on the side of its surface facing away from the current collector.

[0132] Preparation method of composite negative electrode:

[0133] (1) Argon ion beam bombardment treatment: Take a copper foil current collector with a thickness of 12µm, and place the copper foil current collector under a vacuum degree ≤5×10 -3 Pa, ion bombardment energy 800 eV, ion beam current density 0.2 mA / cm² 2Under certain conditions, the copper foil current collector was bombarded with argon ion beam for 120 seconds to activate its surface. After activation, the surface roughness of the copper foil current collector was approximately 200 nm.

[0134] (2) Preparation of lithium metal layer: under a vacuum of 1×10 -3 A 10 μm lithium metal layer was prepared by vacuum evaporation at a deposition rate of 0.5 nm / s under conditions of Pa and substrate temperature of 25 °C; the areal capacity of the lithium metal layer was 2 mAh / cm². 2 Simultaneously, after the lithium metal layer preparation step, the pressure is maintained at this vacuum level for 25 minutes to eliminate stress.

[0135] (3) Preparation of Al2O3 inorganic metal oxide layer: Alumina was prepared by magnetron sputtering using a roll-to-roll production line under the conditions of 80W magnetron sputtering power, 20sccm argon flow rate, 60℃ substrate temperature and 8sccm oxygen flow rate. The transport rate of the alumina intermediate to be prepared was 2.5m / min. A 12nm Al2O3 inorganic metal oxide layer was deposited on the surface of the lithium metal layer.

[0136] (4) Preparation of the CH3NH2SnBr3 perovskite layer:

[0137] (4-1) Prepare CH3NH2Br and SnBr2 in a molar ratio of 1:1 according to the stoichiometric ratio of CH3NH2SnBr3. After adding SnCl2, a mixture is obtained. The mass fraction of SnCl2 in the mixture is 5%.

[0138] (4-2) The mixture was ball-milled at 400 rpm, room temperature and 25% humidity; it was then subjected to a first annealing treatment at 80℃ for 2 h, a second annealing treatment at 200℃ for 2 h, and a third annealing treatment at 300℃ for 12 h; after annealing, it was pressed into shape. The process parameters for pressing into shape included: pressing pressure of 150 tons and pressing time of 6 min, to prepare the target material.

[0139] (4-3) Using the target material as the target, a 120 nm CH3NH2SnBr3 perovskite layer was prepared by radio frequency magnetron sputtering under the conditions of 100 W power, 18 sccm argon flow rate, 1 Pa pressure, and 60 °C substrate temperature using a roll-to-roll production line. In the production line, the transport rate of the intermediate perovskite layer to be prepared was 1 m / min.

[0140] (5) Hole opening treatment: Using the side of the CH3NH2SnBr3 perovskite layer facing away from the Al2O3 inorganic metal oxide layer as the opening surface, a precision laser drilling device is used to perform hole opening treatment, so that the CH3NH2SnBr3 perovskite layer and the Al2O3 inorganic metal oxide layer have a micropore array structure, and the micropores penetrate through the CH3NH2SnBr3 perovskite layer and the Al2O3 inorganic metal oxide layer. The pore diameter of the micropores in the micropore array structure is 30µm; the total area of ​​the micropores in the micropore array structure accounts for 45% of the surface area of ​​the Al2O3 inorganic oxide layer (the surface area of ​​the CH3NH2SnBr3 perovskite layer).

[0141] (6) Filling the microporous array structure on the surface of CH3NH2SnBr3 perovskite layer: Under the conditions of pressure of 30Pa and temperature of 100℃, CH3NH2Br gas was introduced at a flow rate of 8sccm for 12min for the first filling treatment, and then methylamine gas and CH3NH2Br gas with a volume ratio of 1:4 were introduced for 10min for the second filling treatment to prepare composite negative electrode sheet.

[0142] Example 2

[0143] Composite negative electrode: Same as in Example 1.

[0144] Preparation method of composite negative electrode: same as in Example 1. The main difference is that the perovskite layer material CH3NH2SnI3 and the preparation method of step (4) are different in the preparation method of Example 2.

[0145] (4) Preparation of the CH3NH2SnI3 perovskite layer:

[0146] (4-1) Prepare CH3NH2I and SnI2 in a molar ratio of 1:1 according to the stoichiometric ratio of CH3NH2SnI3, and then add SnCl2 to obtain a mixture. The mass fraction of SnCl2 in the mixture is 5%.

[0147] (4-2) The mixture was ball-milled at 400 rpm, room temperature and 25% humidity; it was then subjected to a first annealing treatment at 80℃ for 2 h, a second annealing treatment at 200℃ for 2 h, and a third annealing treatment at 300℃ for 12 h; after annealing, it was pressed into shape. The process parameters for pressing into shape included: pressing pressure of 150 tons and pressing time of 6 min, to prepare the target material.

[0148] (4-3) Using the target material as the target, a 130 nm CH3NH2SnI3 perovskite layer was prepared by radio frequency magnetron sputtering under the conditions of 100 W power, 18 sccm argon flow rate, 1 Pa pressure, and 60 °C substrate temperature using a roll-to-roll production line. In the production line, the transport rate of the intermediate perovskite layer to be prepared was 1 m / min.

[0149] (5) Hole-opening treatment: Using the side of the CH3NH2SnI3 perovskite layer facing away from the Al2O3 inorganic metal oxide layer as the hole-opening surface, a precision laser drilling device is used to perform hole-opening treatment, so that the CH3NH2SnI3 perovskite layer and the Al2O3 inorganic metal oxide layer have a micropore array structure. The micropores penetrate through the CH3NH2SnI3 perovskite layer and the Al2O3 inorganic metal oxide layer. The pore diameter of the micropores in the micropore array structure is 30µm; the total area of ​​the micropores in the micropore array structure accounts for 45% of the surface area of ​​the Al2O3 inorganic oxide layer (the surface area of ​​the CH3NH2SnI3 perovskite layer).

[0150] (6) Filling the microporous array structure on the surface of CH3NH2SnI3 perovskite layer: Under the conditions of pressure of 40Pa and temperature of 110℃, CH3NH2I gas was introduced at a flow rate of 10sccm for 15min for the first filling treatment, and then methylamine gas and CH3NH2I gas with a volume ratio of 1:3 were introduced for 12min for the second filling treatment to prepare composite negative electrode sheet.

[0151] Example 3

[0152] Composite negative electrode: Same as in Example 1.

[0153] Preparation method of composite negative electrode: same as in Example 1. The main difference is that the inorganic metal oxide layer in the preparation method of Example 3 is TiO2.

[0154] (3) Preparation of TiO2 inorganic metal oxide layer: Titanium oxide was prepared by magnetron sputtering using a roll-to-roll production line under the conditions of magnetron sputtering power of 80W, argon flow rate of 20sccm and substrate temperature of 60℃. The transport rate of the intermediate titanium oxide to be prepared was 2.5m / min. A 12nm TiO2 inorganic metal oxide layer was deposited on the surface of the lithium metal layer.

[0155] Example 4

[0156] Composite negative electrode: Same as in Example 1. The main difference is that no perovskite layer is provided.

[0157] Composite negative electrode: Same as Example 1, the main difference is that step (4) of preparing the perovskite layer is omitted and step (6) of filling the microporous array structure of the perovskite layer is omitted.

[0158] Example 5

[0159] Composite negative electrode: Same as in Example 1.

[0160] The preparation method of the composite negative electrode is the same as in Example 1. The main difference is that the thickness of the perovskite layer in the preparation method of Example 5 is 90 nm.

[0161] Example 6

[0162] Composite negative electrode: Same as in Example 1.

[0163] The preparation method of the composite negative electrode is the same as in Example 1. The main difference is that the thickness of the perovskite layer in the preparation method of Example 5 is 160 nm.

[0164] Example 7

[0165] Composite negative electrode: Same as in Example 1.

[0166] Preparation method of composite negative electrode: same as in Example 1. The main difference is that step (5) in the preparation method of Example 7 is different from that in Example 1. In step (5) of Example 7, the pore size of the micropores in the micropore array structure is 10µm.

[0167] Example 8

[0168] Composite negative electrode: Same as in Example 1.

[0169] Preparation method of composite negative electrode: same as in Example 1. The main difference is that step (5) in the preparation method of Example 8 is different from that in Example 1. In step (5) of Example 8, the pore size of the micropores in the micropore array structure is 50µm.

[0170] Example 9

[0171] Composite negative electrode: Same as in Example 1.

[0172] Preparation method of composite negative electrode: Same as in Example 1. The main difference is that step (6) in the preparation method of Example 9 is different from that in Example 1. In step (6) of Example 9: a second filling treatment of methylamine gas and CH3NH2Br gas with a volume ratio of 1:2 is introduced for 10 min to prepare composite negative electrode.

[0173] Example 10

[0174] Composite negative electrode: Same as in Example 1.

[0175] Preparation method of composite negative electrode: Same as in Example 1. The main difference is that step (6) in the preparation method of Example 10 is different from that in Example 1. In step (6) of Example 10: a second filling treatment of methylamine gas and CH3NH2Br gas with a volume ratio of 1:6 is introduced for 10 min to prepare composite negative electrode.

[0176] Comparative Example 1

[0177] Composite negative electrode: includes a current collector and a lithium metal layer disposed on the surface of the current collector.

[0178] Preparation method of composite negative electrode:

[0179] (1) Argon ion beam bombardment treatment: Take a copper foil current collector with a thickness of 12µm, and place the copper foil current collector under a vacuum degree ≤5×10 -3 Pa, ion bombardment energy 800 eV, ion beam current density 0.2 mA / cm² 2 Under certain conditions, the copper foil current collector was bombarded with argon ion beam for 120 seconds to activate its surface. After activation, the surface roughness of the copper foil current collector was approximately 200 nm.

[0180] (2) Preparation of lithium metal layer: under a vacuum of 1×10 -3 A 10 μm lithium metal layer was prepared by vacuum evaporation at a deposition rate of 0.5 nm / s under conditions of Pa and substrate temperature of 25 °C; the areal capacity of the lithium metal layer was 2 mAh / cm². 2 Simultaneously, after the lithium metal layer preparation step, the pressure is maintained at this vacuum level for 25 minutes to eliminate stress.

[0181] Comparative Example 2

[0182] Composite negative electrode: includes a current collector and a lithium metal layer and a perovskite layer sequentially disposed on the surface of the current collector.

[0183] Preparation method of composite negative electrode:

[0184] (1) Argon ion beam bombardment treatment: Take a copper foil current collector with a thickness of 12µm, and place the copper foil current collector under a vacuum degree ≤5×10 -3 Pa, ion bombardment energy 800 eV, ion beam current density 0.2 mA / cm² 2 Under certain conditions, the copper foil current collector was bombarded with argon ion beam for 120 seconds to activate its surface. After activation, the surface roughness of the copper foil current collector was approximately 200 nm.

[0185] (2) Preparation of lithium metal layer: under a vacuum of 1×10 -3 A 10 μm lithium metal layer was prepared by vacuum evaporation at a deposition rate of 0.5 nm / s under conditions of Pa and substrate temperature of 25 °C; the areal capacity of the lithium metal layer was 2 mAh / cm².2 Simultaneously, after the lithium metal layer preparation step, the pressure is maintained at this vacuum level for 25 minutes to eliminate stress.

[0186] (3) Preparation of the CH3NH2SnBr3 perovskite layer:

[0187] (3-1) Prepare CH3NH2Br and SnBr2 in a molar ratio of 1:1 according to the stoichiometric ratio of CH3NH2SnBr3. After adding SnCl2, a mixture is obtained. The mass fraction of SnCl2 in the mixture is 5%.

[0188] (3-2) The mixture was ball-milled at a speed of 400 rpm, a temperature of room temperature, and a humidity of 25%; a first annealing treatment was performed at 80℃ for 2 hours, a second annealing treatment was performed at 200℃ for 2 hours, and a third annealing treatment was performed at 300℃ for 12 hours; after annealing, it was pressed into shape. The process parameters for pressing into shape included: pressing pressure of 150 tons and pressing time of 6 minutes, to prepare the target material.

[0189] (3-3) Using the target material as the target, a 120 nm CH3NH2SnBr3 perovskite layer was prepared by radio frequency magnetron sputtering under the conditions of 100 W power, 18 sccm argon flow rate, 1 Pa pressure, and 60 °C substrate temperature using a roll-to-roll production line. In the production line, the transport rate of the intermediate perovskite layer to be prepared was 1 m / min.

[0190] Comparative Example 3

[0191] The difference from Example 1 is that Comparative Example 3 did not perform the opening process of step (5) and the step of filling the microporous array structure on the surface of the CH3NH2SnBr3 perovskite layer in step (6).

[0192] The composite negative electrode sheets from the above embodiments and comparative examples were assembled into coin cells. The electrolyte in the coin cells was a 1 mol / L LiPF6 electrolyte, and the solvent was EC and DEC in a 1:1 volume ratio. The coin cells were tested at a 1C rate. The corresponding test results are shown in Table 1.

[0193] Table 1

[0194]

[0195] Furthermore, after cycling, the composite negative electrode sheets prepared in the above embodiments all showed better capacity retention compared to Comparative Examples 1 to 3.

[0196] A comparison of the data in Table 1 reveals that the performance differences among the various embodiments mainly stem from the synergistic effect of the inorganic / perovskite layer, the perovskite thickness window, pore structure parameters, and secondary filling conditions. Example 1, with its Al2O3 and CH3NH2SnBr3 bilayer structure, achieved the best cycling stability and lowest interfacial impedance, demonstrating the optimal synergistic effect of this combination in achieving both mechanical barrier and ion channel functions. Examples 3 and 2, despite changing the inorganic layer or perovskite composition, maintained high performance, validating the universality of the "inorganic-organic composite bilayer structure" design concept. The comparison between Examples 5 and 6 shows an optimal window for perovskite layer thickness (approximately 100-150 nm); too thin a layer results in insufficient coverage, while too thick a layer restricts ion migration. The results of Examples 7 and 8 show that the micropore array pore size significantly affects the uniformity of current distribution; too small a pore size leads to local current concentration, while too large a pore size weakens the dendrite barrier effect. Examples 9 and 10 demonstrate that the secondary filling ratio is sensitive to pore repair and lattice orientation control, with the optimal conditions being 1:3 to 1:4. If the perovskite layer is removed (Example 4) or only the Cu matrix is ​​used (Comparative Example 1), the electrochemical performance is slightly worse, further confirming the necessity of the composite bilayer structure.

[0197] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0198] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A composite negative electrode, characterized in that, include: A current collector and a lithium metal layer and an inorganic metal oxide layer sequentially disposed on the surface of the current collector; The inorganic metal oxide layer is made of one or more of aluminum oxide and titanium oxide; the inorganic metal oxide layer has a through-hole array structure.

2. The composite negative electrode sheet according to claim 1, characterized in that, The current collector has one or more of the following characteristics: (1) The thickness of the inorganic metal oxide layer is 10 nm to 15 nm; (2) The pore size of the micropores in the micropore array structure is 20µm~40µm; (3) On the side of the inorganic metal oxide layer facing away from the current collector, the total area of ​​the micropores in the micropore array structure accounts for 40% to 60%.

3. The composite negative electrode sheet according to claim 1, characterized in that, The thickness of the current collector is 6µm to 20µm; And / or, the current collector is copper; And / or, the thickness of the lithium metal layer is 6µm to 20µm.

4. The composite negative electrode sheet according to claim 1, characterized in that, The composite negative electrode also includes a perovskite layer disposed on the surface of the inorganic metal oxide layer facing away from the lithium metal layer; The material of the perovskite layer includes CH3NH2SnX3, where X is one or more of Br and I; The thickness of the perovskite layer is 100nm~150nm.

5. A method for preparing a composite negative electrode, characterized in that, Includes the following steps: A lithium metal layer and an inorganic metal oxide layer are sequentially prepared on the surface of the current collector; The inorganic metal oxide layer is opened by using the side of the inorganic metal oxide layer facing away from the lithium metal layer as the opening surface, so that the inorganic metal oxide layer has a through-hole micropore array structure; wherein, the material of the inorganic metal oxide layer includes one or more of aluminum oxide and titanium oxide.

6. The method for preparing the composite negative electrode sheet according to claim 5, characterized in that, After the step of preparing the inorganic metal oxide layer and before the step of performing the pore opening process, the method further includes: Preparation of a perovskite layer on the surface of the inorganic metal oxide layer opposite to the lithium metal layer; The material of the perovskite layer includes CH3NH2SnX3, where X is one or more of Br and I; The perovskite layer preparation steps include: CH3NH2X and SnX2 are prepared according to the stoichiometric ratio of CH3NH2SnX3, and SnCl2 is added to obtain a mixture; wherein, the mass fraction of SnCl2 in the mixture is 4%~7%; The mixture is ball-milled, annealed, and pressed into shape to prepare the target material. The perovskite layer is prepared using the target material as the target material and a radio frequency magnetron sputtering process.

7. The method for preparing the composite negative electrode sheet according to claim 6, characterized in that, The process parameters for ball milling include: rotation speed of 300 rpm to 600 rpm, temperature of 20℃ to 35℃, and humidity of 20% to 30%. And / or, the annealing step includes: a first annealing treatment at 75℃~85℃ for 1h~3h, a second annealing treatment at 180℃~220℃ for 1h~3h, and a third annealing treatment at 290℃~310℃ for 10h~14h; And / or, the process parameters for compression molding include: compression pressure of 100 tons to 200 tons, and compression time of 3 min to 10 min; And / or, the process parameters for preparing the perovskite layer using radio frequency magnetron sputtering include: power of 80W~120W, argon flow rate of 15sccm~25sccm, pressure of 0.8Pa~1.2Pa, and substrate temperature of 40℃~70℃.

8. The method for preparing the composite negative electrode sheet according to claim 6, characterized in that, The opening process includes: using the surface of the perovskite layer facing away from the inorganic metal oxide layer as the opening surface for opening process, so that both the perovskite layer and the inorganic metal oxide layer have a through-hole array structure. Following the pore-opening process, the method further includes filling the microporous array structure in the perovskite layer with CH3NH2X and / or methylamine to prepare the composite negative electrode sheet.

9. The method for preparing the composite negative electrode sheet according to claim 8, characterized in that, The steps for filling the microporous array structure in the perovskite layer include: Under conditions of pressure of 10Pa~50Pa and temperature of 80℃~120℃, CH3NH2X gas is introduced at a flow rate of 5sccm~10sccm for the first filling treatment, and then methylamine gas and CH3NH2X gas with a volume ratio of 1:(3~5) are introduced for the second filling treatment.

10. The method for preparing the composite negative electrode sheet according to any one of claims 5 to 9, characterized in that, The lithium metal layer preparation steps include: [under a vacuum degree ≤ 1×10] -3 The lithium metal layer was prepared by vacuum evaporation at a deposition rate of 0.1 nm / s to 1 nm / s under the condition of Pa.

11. The method for preparing the composite negative electrode sheet according to any one of claims 5 to 9, characterized in that, Before the step of preparing the lithium metal layer on the surface of the current collector, the method further includes: The current collector is placed under a vacuum degree ≤5×10 -3 Pa, ion bombardment energy 500 eV~1000 eV, ion beam current density 0.1 mA / cm² 2 ~0.3mA / cm 2 Argon ion beam bombardment was performed under these conditions.

12. The method for preparing the composite negative electrode sheet according to any one of claims 5 to 9, characterized in that, The inorganic metal oxide layer is prepared by magnetron sputtering. The inorganic metal oxide layer is made of aluminum oxide, and the preparation steps of the inorganic metal oxide layer include: using aluminum as a target material, depositing the inorganic metal oxide layer on the surface of the lithium metal layer under the conditions of magnetron sputtering power of 50W~90W, argon flow rate of 15sccm~25sccm, substrate temperature of 50℃~70℃, and oxygen flow rate of 5sccm~10sccm; And / or, the material of the inorganic metal oxide layer includes titanium oxide, and the preparation steps of the inorganic metal oxide layer include: using titanium oxide as a target, depositing the inorganic metal oxide layer on the surface of the lithium metal layer under the conditions of magnetron sputtering power of 60W~100W, argon flow rate of 12sccm~20sccm, and substrate temperature of 50℃~80℃.

13. A battery, characterized in that, It includes the composite negative electrode sheet according to any one of claims 1 to 4, or the composite negative electrode sheet prepared by any one of claims 5 to 12.

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