A pre-lithium-supplemented current collector, a preparation method thereof, a negative electrode, and a full-solid-state battery

Abstract

The present application relates to the technical field of all-solid-state batteries, and particularly relates to a pre-lithium supplement current collector, a preparation method thereof, a negative electrode and an all-solid-state battery. The pre-lithium supplement current collector is prepared from metallic lithium and a three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure. The three-dimensional porous copper alloy current collector is composed of copper elements and alloying elements capable of alloying with lithium. The metallic lithium is filled in and sealed in the pores of the three-dimensional porous copper alloy current collector, and a lithium-alloying element intermetallic compound layer is formed in situ between the metallic lithium and the three-dimensional porous copper alloy current collector. Through the synergistic effect of filling and sealing the pores with metallic lithium and forming a lithium-alloying interface layer by the alloying of lithium and alloying elements, the present application can not only realize long-term lithium supplement, but also significantly reduce the interface side reactions, and can also enhance the stability of the negative electrode and the interface adaptability, thereby improving the electrochemical performance of the battery.

Description

Technical Field

[0001] This invention relates to the field of all-solid-state battery technology, and more specifically, to a pre-replenished lithium current collector and its preparation method, a negative electrode, and an all-solid-state battery. Background Technology

[0002] All-solid-state batteries, due to their use of inorganic solid-state electrolytes instead of traditional liquid electrolytes, possess significant advantages such as high intrinsic safety, a wide electrochemical window, and great potential for energy density improvement, and are considered an important development direction for next-generation high-energy-density battery systems. However, the cycle performance of all-solid-state batteries remains a key bottleneck restricting their commercial application, especially when high-energy-density materials (such as high-silicon anodes and lithium metal anodes) are used on the negative electrode side, where the problem is particularly prominent.

[0003] Specifically, both high-silicon anodes and lithium metal anodes exhibit significant volume effects and interface reactions during charge and discharge. Silicon-based materials can experience volume expansion exceeding 300% in the lithium-intercalated state, while lithium metal anodes face unlimited volume changes due to the lack of a host structure. Both readily lead to deterioration of the solid-solid interface contact between the anode and the solid electrolyte, resulting in a continuous increase in interface impedance. Furthermore, lithium metal anodes are prone to forming lithium dendrites during repeated deposition / stripping processes. These dendrites may penetrate the solid electrolyte layer, causing internal micro-short circuits or even battery failure, seriously threatening battery safety and cycle stability.

[0004] To mitigate capacity decay caused by irreversible consumption of active lithium, negative electrode lithium replenishment technology is considered an effective strategy. By introducing an additional lithium source on the negative electrode side beforehand, the active lithium consumed by the formation of the solid electrolyte interphase (SEI) film and side reactions can be compensated, thereby extending battery life. However, existing lithium replenishment methods used in all-solid-state batteries mostly employ physical bonding methods, such as directly laminating lithium metal foil or lithium alloy films onto the silicon-based negative electrode surface through roll forming. Practice has shown that this lithium replenishment method has the following significant drawbacks: (1) Uncontrollable lithium source release: The lithium metal directly injected participates in the reaction in large quantities in the initial cycle, and the lithium source release is too concentrated, making it difficult to slowly and continuously replenish active lithium in the long cycle process. The lithium replenishment efficiency decreases significantly with the cycle.

[0005] (2) Increased interfacial side reactions: A large amount of lithium metal is directly exposed at the negative electrode / electrolyte interface, which is prone to side reactions with solid electrolyte, generating high-impedance interfacial byproducts, which in turn leads to increased battery polarization and decreased rate performance and cycle life.

[0006] (3) Poor structural adaptability: The rigid pressing method is difficult to adapt to the volume change of the negative electrode during cycling. The interface peeling between the lithium replenishment layer and the negative electrode body is prone to occur, which further deteriorates the interface contact.

[0007] In view of this, the present invention is hereby proposed. Summary of the Invention

[0008] The primary objective of this invention is to provide a pre-replenished lithium current collector. Through the synergistic effect of filling and sealing the pores with metallic lithium and forming a lithium-alloy interface layer by utilizing the alloying effect of lithium and alloying elements, it can achieve long-term lithium replenishment, be compatible with the negative electrode, and maintain good interface contact. This solves the problems of uncontrollable lithium source release, severe interface side reactions, and poor compatibility between the replenishment layer and the negative electrode in existing all-solid-state battery negative electrode lithium replenishment technologies.

[0009] The second objective of this invention is to provide a method for preparing a pre-replenished lithium current collector.

[0010] A third objective of this invention is to provide a negative electrode.

[0011] The fourth objective of this invention is to provide an all-solid-state battery.

[0012] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The present invention first provides a pre-filled lithium current collector, which is obtained by metallic lithium and a three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure; wherein, the three-dimensional porous copper alloy current collector is mainly composed of copper element and alloying elements that can undergo alloying reaction with lithium; the metallic lithium fills and seals the pores of the three-dimensional porous copper alloy current collector, and there is an in-situ formed lithium-alloy element intermetallic compound layer between the metallic lithium and the three-dimensional porous copper alloy current collector.

[0013] Furthermore, prior to the filling, the porosity of the three-dimensional porous copper alloy current collector is 40%~85%, and the average pore size of the three-dimensional porous copper alloy current collector is 5μm~50μm.

[0014] Furthermore, after the filling and sealing, the porosity of the pre-filled lithium current collector is 5% to 20%.

[0015] Furthermore, prior to the filling, the Young's modulus of the three-dimensional porous copper alloy current collector is ≥120 GPa.

[0016] Furthermore, the alloying element includes one or more of Sn, Si, Al, Zn and Mg.

[0017] Furthermore, the mass fraction of the alloying elements in the three-dimensional porous copper alloy current collector is 1% to 15%.

[0018] The present invention also provides a method for preparing the above-mentioned pre-filled lithium current collector, comprising the following steps: using a fused deposition method or a hot rolling method to fill the pores of a three-dimensional porous copper alloy current collector with metallic lithium to obtain a lithium-filled composite material; and rolling the lithium-filled composite material to seal the metallic lithium within the pores.

[0019] Furthermore, the fused deposition method specifically includes the following steps: under an inert atmosphere, the three-dimensional porous copper alloy current collector is immersed in molten lithium metal, and the molten lithium metal is drawn into the pores of the three-dimensional porous copper alloy current collector by capillary force.

[0020] Further, the hot rolling method specifically includes the following steps: placing a lithium metal foil on one or both sides of the three-dimensional porous copper alloy current collector, and pressing the lithium metal foil into the pores of the three-dimensional porous copper alloy current collector by heating and rolling; wherein, the temperature of the heating and rolling is 100℃~200℃, and the linear pressure of the heating and rolling is 50N / cm~300N / cm.

[0021] Furthermore, prior to the filling, the three-dimensional porous copper alloy current collector undergoes pretreatment, which includes heating under inert gas protection.

[0022] Furthermore, the temperature of the roll forming is 20~150℃.

[0023] Furthermore, the linear pressure of the roll forming is 50 N / cm to 300 N / cm.

[0024] Furthermore, after the roll forming, the porosity of the three-dimensional porous copper alloy current collector is reduced to 5%~20%.

[0025] Furthermore, the three-dimensional porous copper alloy current collector is prepared by template method, dealloying method or foam metal electrodeposition method.

[0026] The present invention further provides a negative electrode, which uses the above-mentioned pre-replenished lithium current collector directly as the negative electrode, or is composed of the above-mentioned pre-replenished lithium current collector and a negative electrode active material layer loaded on the surface of the pre-replenished lithium current collector.

[0027] The present invention also provides an all-solid-state battery, which includes the above-mentioned negative electrode, as well as a solid electrolyte layer and a positive electrode.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The pre-replenished lithium current collector provided by the present invention can achieve long-term lithium replenishment, and can be compatible with the negative electrode and maintain good interface contact, thus solving the balance problem between the controllable release of active lithium and interface stability.

[0029] (2) The pre-replenished lithium current collector provided by the present invention can achieve slow and controllable release of lithium source by embedding metallic lithium in closed pores and utilizing the alloying effect of lithium and alloying elements. It can continuously and stably replenish active lithium during long cycle, effectively alleviate capacity decay, and significantly improve the cycle life of all-solid-state batteries.

[0030] (3) The pre-filled lithium current collector provided by the present invention is filled with metallic lithium and sealed inside the current collector by rolling, which avoids direct contact with the solid electrolyte, thereby suppressing the harmful side reaction between lithium and electrolyte, reducing the interface impedance, and improving the rate performance and cycle stability of the battery.

[0031] (4) The pre-replenished lithium current collector provided by the present invention has pores inside the three-dimensional porous copper alloy current collector that provide physical space for lithium deposition / stripping; the three-dimensional porous copper alloy current collector with high Young's modulus maintains structural stability throughout the cycle; at the same time, the alloy layer and the current collector form an integrated structure, which improves the bonding force between the lithium replenishment layer and the negative electrode body, prevents interface stripping, and ensures solid-solid interface contact during long-term cycling; thereby significantly enhancing the stability and interface compatibility of the negative electrode.

[0032] (5) The pre-replenished lithium current collector provided by the present invention has significantly improved air stability after the lithium metal is alloyed and the pores are sealed, which greatly improves process safety and operability.

[0033] (6) The pre-replenished lithium current collector provided by the present invention can be used directly as a negative electrode, or it can be used as a negative electrode after a negative electrode active material layer is formed on its surface. Detailed Implementation

[0034] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0035] Unless otherwise specified, in this invention, terms such as "first aspect," "second aspect," "third aspect," and "fourth aspect" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or quantity, nor should they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, terms such as "first," "second," "third," and "fourth" serve only as a non-exhaustive enumeration and should be understood not to constitute a closed limitation on quantity.

[0036] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0037] Unless otherwise specified, in this invention, "one or more" or "at least one" refers to any one, any two, or any two or more of the listed items. "Several" refers to any two or more.

[0038] In a first aspect, the present invention provides a pre-filled lithium current collector for the negative electrode of an all-solid-state battery, which is made of metallic lithium and a three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure. The pore structure of the three-dimensional porous copper alloy current collector not only accommodates the lithium source but also serves as a buffer for volume expansion and a space for homogenizing current density.

[0039] The three-dimensional porous copper alloy current collector is mainly composed of copper and alloying elements that can undergo alloying reactions with lithium. It is understood that the material of the three-dimensional porous copper alloy current collector is a copper alloy, and the copper alloy of this invention incorporates elements that can undergo alloying reactions with lithium (Sn, Al, Si, etc.), rather than using pure copper. It is understood that after metallic lithium comes into contact with the three-dimensional porous copper alloy current collector, a lithium-alloying element intermetallic compound layer (such as Li-Sn alloy, Li-Al alloy, etc.) is formed in situ at the interface, and this alloy layer plays a connecting and slow-release role.

[0040] The metallic lithium fills and seals the pores of the three-dimensional porous copper alloy current collector, and an in-situ formed lithium-alloy element intermetallic compound layer exists between the metallic lithium and the three-dimensional porous copper alloy current collector. Specifically, the in-situ lithium alloy layer formed between the alloying elements and lithium (such as Li3Sn, LiAl, Li...) xSi combines the dual functions of "chemical anchoring" and "slow-release regulation," enhancing the binding force between lithium and the framework while controlling the lithium release rate. That is, the lithium source is not released all at once, but rather continuously replenished with active lithium during long-term cycling through diffusion control via the alloy layer. Simultaneously, by encapsulating the metallic lithium within the three-dimensional porous copper alloy current collector, isolating it from the external environment (including the solid electrolyte and air), it fundamentally suppresses interfacial side reactions and activity loss during the process.

[0041] The pre-replenished lithium current collector provided by this invention enables slow and controllable release of lithium source: by embedding metallic lithium in closed pores and using a copper alloy containing lithium-philic alloying elements (Sn, Al, etc.), a lithium-alloy interface layer is formed by the alloying effect of lithium and alloying elements. The lithium release process is controlled by diffusion, which can continuously and stably replenish active lithium during long-term cycling, effectively alleviate capacity decay, and significantly improve the cycle life of all-solid-state batteries. The mechanism is as follows: after the lithium filling the pores comes into contact with the copper alloy, it first reacts at the interface to form a lithium alloy phase with high ionic conductivity (such as Li3Sn, LiAl). This alloy layer acts as a "lithium source slow-release layer," and its decomposition potential is slightly higher than that of pure lithium, making it more thermodynamically stable. During battery cycling, when the active lithium in the negative electrode is consumed due to SEI formation or side reactions, the lithium inside the pores will preferentially diffuse outward through the alloy layer to replenish it. The closed pore structure restricts the direct exposure of lithium, making the lithium release path longer, and the release rate is controlled by solid-phase diffusion in the alloy layer, thereby achieving a slow-release effect. Therefore, unlike the existing technology where the lithium source is released in a concentrated manner in the first cycle, the present invention realizes the "on-demand replenishment" of lithium, which significantly extends the duration of the lithium replenishment effect, that is, it realizes the slow and controllable release of the lithium source.

[0042] The pre-replenished lithium current collector provided by this invention can also significantly reduce interfacial side reactions: metallic lithium is filled and rolled and sealed inside the current collector, avoiding direct contact with the solid electrolyte, thereby suppressing harmful side reactions between lithium and electrolyte, reducing interfacial impedance, and improving the rate performance and cycle stability of the battery. In the traditional direct pressing lithium replenishment process, lithium metal is exposed over a large area at the electrode / electrolyte interface, which is highly susceptible to redox reactions with sulfide or oxide solid electrolytes, generating high-impedance byproducts such as Li2S and Li3P. In this invention, after pore sealing treatment, lithium metal is physically encapsulated inside the copper alloy matrix, blocking the contact path with the external solid electrolyte; what directly contacts the solid electrolyte is the more chemically inert copper alloy framework or dense alloy layer, rather than the highly active metallic lithium. Therefore, this invention significantly suppresses the occurrence of interfacial side reactions, resulting in lower and more stable interfacial impedance.

[0043] The pre-replenished lithium current collector provided by this invention also enhances the stability and interface compatibility of the negative electrode: the three-dimensional porous structure provides a buffer space for lithium deposition / stripping, effectively accommodating volume changes during cycling and maintaining the integrity of the electrode structure; simultaneously, the alloy layer and the current collector form an integrated structure, improving the bonding force between the replenished lithium layer and the negative electrode body, preventing interface stripping, and ensuring solid-solid interface contact during long-term cycling. This achieves long-term stable contact between the electrode and the solid electrolyte interface, significantly improving cycle life.

[0044] The pores within the three-dimensional porous copper alloy current collector provide physical space for lithium deposition / stripping. During cycling, the pore structure shrinks as lithium dissolves from the pores; during redeposition, lithium preferentially fills the pores, reducing overall macroscopic volume fluctuations in the electrode, thus buffering volume changes. The large specific surface area of ​​the three-dimensional framework significantly reduces local current density, suppresses lithium dendrite nucleation and growth, prevents dendrites from piercing the solid electrolyte, and homogenizes the current density.

[0045] The high Young's modulus three-dimensional porous copper alloy current collector (copper alloy skeleton) maintains structural stability throughout the cycle. Even if the internal lithium is consumed, the skeleton is not easy to collapse, ensuring the smooth electronic pathway during long-term cycling and playing a mechanical support role.

[0046] Furthermore, the pre-replenished lithium current collector provided by this invention significantly improves process safety and operability: after alloying and pore sealing, the air stability of metallic lithium is significantly improved, making it less prone to oxidation or activity loss during electrode preparation processes (such as coating and rolling), reducing the requirements for the production environment, and exhibiting good process compatibility and prospects for large-scale production. It is understood that metallic lithium readily reacts with H2O, O2, and N2 in air to generate LiOH, Li2O, Li3N, etc., leading to activity loss and the risk of heat generation. In this invention, after rolling sealing, the lithium is encased in a dense copper alloy shell, isolating it from direct contact with air; and the lithium on the surface and near the surface preferentially reacts with alloying elements, transforming into a more chemically stable lithium alloy phase, reducing its natural activity.

[0047] In some specific embodiments, the pre-replenished lithium current collector can be exposed for a short time in a drying room with low relative humidity (dew point below -30°C), and roll-to-roll coating may even be achieved. This invention significantly reduces production costs and safety risks.

[0048] In summary, this invention achieves efficient and controllable replenishment of lithium sources through the structural design of a three-dimensional porous copper alloy current collector and the synergistic effect of alloying, while improving interface stability and process safety, providing an effective solution for improving the long-cycle performance of all-solid-state batteries.

[0049] In some specific embodiments, prior to the filling, the porosity of the three-dimensional porous copper alloy current collector is 40% to 85%, for example, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, or 85%. Controlling the above porosity ensures sufficient space to accommodate metallic lithium and buffers volume expansion.

[0050] In some specific embodiments, the average pore size of the three-dimensional porous copper alloy current collector is 5μm to 50μm, for example, 5μm, 10μm, 15μm, 20μm, 25μm, 30μm, 35μm, 40μm, 45μm, or 50μm. Controlling the above average pore size facilitates the filling and sealing of metallic lithium. If the pore size of the three-dimensional porous copper alloy current collector is too small, it is not conducive to the filling of metallic lithium; if the pore size is too large, it is difficult to effectively seal and suppress dendrite growth. The average pore size of the three-dimensional porous copper alloy current collector is preferably 10μm to 30μm.

[0051] In some specific embodiments, after the filling and the sealing, the porosity of the pre-filled lithium current collector is 5% to 20%, for example 5%, 8%, 10%, 13%, 15%, 17% or 20%.

[0052] In some specific embodiments, before the filling, the Young's modulus of the three-dimensional porous copper alloy current collector is ≥120 GPa, for example, 120 GPa, 121 GPa, 122 GPa, 123 GPa, 124 GPa, 125 GPa, 126 GPa, 127 GPa, 128 GPa, 129 GPa, 130 GPa, 135 GPa, or 140 GPa. By controlling the porosity, average pore size, and Young's modulus of the three-dimensional porous copper alloy current collector before filling, the structural stability and interface compatibility of the negative electrode can be enhanced.

[0053] In some specific embodiments, the thickness of the three-dimensional porous copper alloy current collector can be designed according to the battery capacity, and the present invention does not limit this. For example, before filling, the thickness of the three-dimensional porous copper alloy current collector can be 20μm~200μm, such as 20μm, 50μm, 80μm, 100μm, 130μm, 150μm, 180μm or 200μm.

[0054] In some specific embodiments, the alloying elements include one or more of Sn, Si, Al, Zn, and Mg. These alloying elements possess the ability to alloy with lithium (i.e., lithiumophilicity).

[0055] In some specific embodiments, the mass fraction of the alloying element in the three-dimensional porous copper alloy current collector is 1% to 15%, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, or 15%. The alloying element undergoes an alloying reaction with lithium to form a stable lithium alloy phase, which acts as a lithium replenisher, slowly releasing lithium during cycling to compensate for lithium loss. The lithium release process after alloying is diffusion-controlled, enabling continuous and stable replenishment of active lithium during long cycles, effectively mitigating capacity decay and significantly improving the cycle life of the all-solid-state battery. This approach avoids the drawbacks of directly pressing lithium sheets into copper foil or porous copper foil, such as uncontrollable lithium source release: directly pressed lithium metal participates in the reaction in large quantities during the initial cycle, resulting in overly concentrated lithium source release and making it difficult to slowly and continuously replenish active lithium during long cycles, leading to a significant decrease in replenishment efficiency with each cycle; furthermore, directly pressing lithium metal exposes a large amount of lithium metal to the negative electrode / electrolyte interface, making it prone to side reactions with the solid electrolyte, generating high-resistivity interface byproducts, which in turn increases battery polarization and reduces rate performance and cycle life. In contrast, this application uses alloyed lithium, changing the lithium source from metallic lithium to alloyed lithium, reducing reactivity and significantly improving interface issues.

[0056] Secondly, the present invention provides a method for preparing the above-mentioned pre-replenished lithium current collector, comprising the following steps: Lithium-filled composite materials are obtained by filling the pores of a three-dimensional porous copper alloy current collector with metallic lithium using either fused deposition or hot rolling.

[0057] The lithium-filled composite material is then rolled to seal the metallic lithium within the pores. The purpose of rolling is to close the pores on the surface of the three-dimensional porous copper alloy current collector, forming a dense "skin layer" that physically isolates the internal metallic lithium from the external environment.

[0058] This invention uses a three-dimensional porous copper alloy current collector as a pre-lithiation carrier. Metallic lithium is filled into the pores of the three-dimensional porous copper alloy current collector through hot rolling or melt deposition. The pores are then sealed by rolling, thus encapsulating the metallic lithium within the three-dimensional porous copper alloy current collector, achieving effective lithium filling and sealing. Simultaneously, the alloying elements in the three-dimensional porous copper alloy current collector undergo an alloying reaction with lithium, forming a stable lithium alloy phase (i.e., a lithium-alloy element intermetallic compound layer).

[0059] The pre-replenished lithium current collector prepared using this method enables slow and controllable release of the lithium source, significantly reduces interfacial side reactions, enhances anode stability and interface compatibility, and greatly improves process safety and operability. The resulting all-solid-state battery exhibits superior rate performance and significantly improved cycle life. This method solves three major challenges in all-solid-state battery anode lithium replenishment technology: uncontrollable lithium source release, severe interfacial side reactions, and poor volume expansion compatibility.

[0060] In some specific embodiments, the fused deposition method specifically includes the following steps: immersing the three-dimensional porous copper alloy current collector in an inert atmosphere (such as an argon atmosphere, preferably in a glove box) for 30-120 seconds in molten lithium metal (at a temperature of 250°C-350°C), and using capillary force to draw the molten lithium metal into the pores of the three-dimensional porous copper alloy current collector.

[0061] In some specific embodiments, the hot rolling method specifically includes the following steps: placing a lithium metal foil on one or both sides of the three-dimensional porous copper alloy current collector, and pressing the lithium metal foil into the pores of the three-dimensional porous copper alloy current collector by heating and rolling. The temperature of the heating and rolling is 100℃~200℃, for example, 100℃, 120℃, 150℃, 180℃, or 200℃. The linear pressure of the heating and rolling is 50N / cm~300N / cm, for example, 60N / cm, 80N / cm, 100N / cm, 150N / cm, 200N / cm, 250N / cm, or 300N / cm.

[0062] In some specific embodiments, the three-dimensional porous copper alloy current collector undergoes pretreatment before filling. This pretreatment includes heating under inert gas protection to remove water and oxygen adsorbed on the surface of the three-dimensional porous copper alloy current collector. The heating temperature can be 150~250℃.

[0063] In some specific embodiments, the rolling temperature is 20~150℃, for example 20℃, 25℃, 30℃, 35℃, 40℃, 50℃, 80℃, 100℃, 120℃ or 150℃.

[0064] In some specific embodiments, the linear pressure of the roll forming is 50N / cm to 300N / cm, for example 60N / cm, 80N / cm, 100N / cm, 150N / cm, 200N / cm, 250N / cm or 300N / cm.

[0065] In some specific embodiments, the porosity of the three-dimensional porous copper alloy current collector is reduced to 5%~20% after the roll forming, for example, 5%, 8%, 10%, 12%, 15%, 18% or 20%.

[0066] In some specific embodiments, the three-dimensional porous copper alloy current collector is prepared by template method, dealloying method or electrodeposition method (foam metal electrodeposition method), and the present invention does not limit this method.

[0067] As a preferred method, the preparation steps of the template method include: printing insulating "ink" onto the cathode to form a template by screen printing, removing the ink after electroplating to obtain through holes, forming a composite structure by electroplating copper and alloying elements respectively, and then sintering at high temperature to form a three-dimensional porous copper alloy current collector.

[0068] The preparation steps of the dealloying method include: rolling copper alloy raw materials into foil, and then corroding away some of the alloy components through electrochemical corrosion to form a three-dimensional porous copper alloy current collector.

[0069] The preparation steps of the electrodeposition method (foam metal electrodeposition method) include: using foam copper as a substrate, depositing an alloy element layer on the skeleton by electroplating or chemical plating, and then diffusing through heat treatment to form a uniform copper alloy skeleton, thus obtaining a three-dimensional porous copper alloy current collector.

[0070] Thirdly, the present invention provides a negative electrode, which uses the above-mentioned pre-replenished lithium current collector directly as the negative electrode, or is composed of the above-mentioned pre-replenished lithium current collector and a negative electrode active material layer loaded on the surface of the pre-replenished lithium current collector.

[0071] That is, the pre-replenished lithium current collector prepared by the present invention can be used directly as the negative electrode of an all-solid-state battery; or it can be used as a current collector by coating the surface of the pre-replenished lithium current collector with a negative electrode slurry to form a negative electrode active material layer loaded on the surface of the pre-replenished lithium current collector.

[0072] Using this negative electrode can improve the electrochemical performance of all-solid-state batteries, especially rate performance and cycle performance.

[0073] Fourthly, the present invention provides an all-solid-state battery, which includes the above-mentioned negative electrode, as well as a solid electrolyte layer and a positive electrode.

[0074] The all-solid-state battery prepared by the above-mentioned pre-replenished lithium current collector or the above-mentioned negative electrode has significantly improved rate performance and cycle performance.

[0075] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0076] Example 1 The method for preparing the pre-replenished lithium current collector provided in this embodiment includes the following steps: (1) Pretreatment: A three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure, a porosity of 65%, an average pore size of 25 μm, a Young's modulus of 120 GPa, and a thickness of 50 μm, is made of Cu-Sn alloy (composed of Cu and Sn elements, with Sn as the alloying element), wherein the mass fraction of Sn is 8 wt.%. The three-dimensional porous Cu-Sn alloy current collector is heated to 200 °C in an argon glove box to remove adsorbed water and oxygen from the surface, thus obtaining the pretreated current collector.

[0077] The three-dimensional porous copper alloy current collector was prepared by electrodeposition. The preparation process is as follows: the three-dimensional porous copper current collector was placed in a Sn electroplating solution, with metallic Sn as the counter electrode and the three-dimensional porous copper current collector as the working electrode, and electroplating was performed, wherein the current density was 2.5 A / dm³. 2 The temperature was 30℃ and the electroplating time was 30min. After electroplating, the obtained Cu-Sn composite foil was washed in distilled water to remove the electrolyte. After drying, it was alloyed in a vacuum furnace at 650℃ for 1h to obtain a three-dimensional porous copper alloy current collector.

[0078] (2) Lithium filling: Under an argon atmosphere, the pretreated current collector is immersed in molten lithium metal at a temperature of 300°C using the melt deposition method. The molten lithium metal is held for 30 seconds and the capillary action is used to draw the molten lithium metal into the pores of the current collector. After being taken out, it is cooled to room temperature (25°C) to obtain a lithium-filled composite material.

[0079] (3) Pore sealing: The lithium-filled composite material obtained above is rolled at 100°C, wherein the linear pressure of the rolling is 150 N / cm, so that the surface pores are closed. After the rolling, the porosity of the three-dimensional porous copper alloy current collector is reduced to 12%, that is, the porosity of the pre-filled lithium current collector is 12%.

[0080] The pre-filled lithium current collector prepared in this embodiment includes a three-dimensional porous copper alloy current collector and metallic lithium filled and sealed therein, and the metallic lithium and the three-dimensional porous copper alloy current collector are in-situ formed lithium-alloy element intermetallic compound layer (Li-Sn alloy).

[0081] The pre-replenished lithium current collector obtained in this embodiment was used to make a negative electrode (silicon-carbon alloy negative electrode) according to the following method: silicon-carbon alloy negative electrode material (Si content of about 15%, theoretical capacity of 800mAh / g), conductive carbon black, sulfide electrolyte (Li6PS5Cl) and binder (styrene-butadiene rubber, SBR) were mixed in a mass ratio of 85:5:5:5, and a negative electrode slurry was prepared with xylene as solvent. The negative electrode slurry was coated on the surface of the pre-replenished lithium current collector with a coating thickness of 30μm. After drying, it was rolled and compacted to obtain the negative electrode.

[0082] The aforementioned negative electrode was then used to fabricate an all-solid-state battery using the following method: Positive electrode: High-nickel ternary material (LiNi 0.8 Co 0.1 Mn 0.1 O2 (NCM811) and sulfide electrolyte (Li6PS5Cl) are combined in a mass ratio of 7:3, with a positive electrode loading of 4.0 mAh / cm³. 2 Electrolyte layer: 50 μm thick, formed by pressing sulfide electrolyte (Li6PS5Cl) powder. The positive electrode, electrolyte layer, and negative electrode were sequentially stacked using a dry process, cold-pressed at 300 MPa, and then encapsulated in a coin cell for testing. The test results are shown in Table 1.

[0083] Comparative Example 1 The preparation method of the pre-replenished lithium current collector provided in this comparative example is as follows: the lithium metal foil is directly bonded to the surface of the copper foil by rolling through a physical pressing method, that is, direct lithium pressing and replenishment.

[0084] Using the pre-replenished lithium current collector prepared in this comparative example, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 1, and their electrochemical performance was tested using the test parameters of Example 1. The test results are shown in Table 1.

[0085] Table 1. Electrochemical performance test results of the batteries in Example 1 and Comparative Example 1

[0086] As shown in Table 1, in Example 1, the Sn in the Cu-Sn alloy current collector forms a Li-Sn alloy layer with the filled lithium in situ, which plays a role in the slow release of lithium source during cycling. Compared with Comparative Example 1 (using two-dimensional copper foil + direct lithium compression), the capacity retention rate after 500 cycles is improved by about 25 percentage points (60.0% in Comparative Example 1), the increase in interface impedance is significantly slowed down, and the interface is stable.

[0087] Example 2 The method for preparing the pre-replenished lithium current collector provided in this embodiment includes the following steps: (1) Pretreatment: A three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure, a porosity of 75%, an average pore size of 15 μm, a Young's modulus of 105 GPa, and a thickness of 60 μm, is made of Cu-Al alloy (composed of Cu and Al elements, with Al as the alloying element), wherein the mass fraction of Al element is 5 wt.%. The three-dimensional porous Cu-Al alloy current collector is heated to 180 °C in an argon glove box to remove adsorbed water and oxygen on the surface, thus obtaining the pretreated current collector.

[0088] The three-dimensional porous copper alloy current collector was prepared by a dealloying method. The preparation process is as follows: copper powder and aluminum powder are mixed in a mass ratio of 9:1 and pressed into a block. Then, they are melted into a melt using an electromagnetic high-frequency heating furnace. The temperature is controlled at 1300℃ and held for 30 minutes to allow the elements to diffuse fully. Then, the melt is cooled to room temperature and the resulting alloy ingot is rolled into an alloy foil with a thickness of 60μm using a rolling mill. Then, the foil is immersed and etched with a 15% dilute hydrochloric acid solution for 3 hours to obtain the three-dimensional porous copper alloy current collector.

[0089] (2) Lithium filling: Under an argon atmosphere, a 20 μm thick lithium foil is placed on both sides of the pretreated current collector and rolled at 150°C and a linear pressure of 200 N / cm to extrude lithium metal into the pores of the current collector, thus obtaining a lithium-filled composite material.

[0090] (3) Pore sealing: The lithium-filled composite material obtained above is rolled at room temperature of 25°C. The linear pressure of the rolling is 250 N / cm, which closes the surface pores. After rolling, the porosity of the three-dimensional porous copper alloy current collector is reduced to 10%, that is, the porosity of the pre-filled lithium current collector is 10%.

[0091] The pre-filled lithium current collector prepared in this embodiment includes a three-dimensional porous copper alloy current collector and metallic lithium filled and sealed therein, and the metallic lithium and the three-dimensional porous copper alloy current collector are in-situ formed lithium-alloy element intermetallic compound layer (Li-Al alloy).

[0092] The pre-replenished lithium current collector obtained in this embodiment was used to prepare a negative electrode (pure silicon negative electrode) as follows: Nano-silicon negative electrode material (purity >99.9%, theoretical capacity 3500 mAh / g), conductive carbon black, sulfide electrolyte (Li6PS5Cl), and polyethylene oxide (PEO) binder were mixed in a mass ratio of 70:10:10:10, and a negative electrode slurry was prepared using acetonitrile as a solvent. The negative electrode slurry was then coated onto the surface of the pre-replenished lithium current collector with a coating thickness of 15 μm (controlling the silicon loading to 1.0 mg / cm²). 2 After drying, the material is rolled to obtain the negative electrode.

[0093] The aforementioned negative electrode was then used to fabricate an all-solid-state battery using the following method: Positive electrode: High-nickel ternary material (LiNi 0.85 Co 0.10 Al 0.05 O2 (NCA) is combined with a sulfide electrolyte (Li6PS5Cl) in a mass ratio of 75:25, with a positive electrode loading of 3.5 mAh / cm³. 2 Electrolyte layer: 40 μm thick, formed by pressing sulfide electrolyte (Li6PS5Cl) powder. The positive electrode, electrolyte layer, and negative electrode were sequentially stacked using a dry process, cold-pressed at 350 MPa, and then encapsulated in a coin cell for testing. The test results are shown in Table 2.

[0094] Comparative Example 2 The preparation method of the pre-replenished lithium current collector provided in this comparative example is as follows: the lithium metal foil is directly bonded to the surface of the copper foil by rolling through a physical pressing method, that is, direct lithium pressing and replenishment.

[0095] Using the pre-replenished lithium current collector of this comparative example, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 2, and their electrochemical performance was tested using the test parameters of Example 2. The test results are shown in Table 2.

[0096] Table 2 Electrochemical performance test results of the batteries in Example 2 and Comparative Example 2

[0097] Pure silicon anodes exhibit significant volume expansion, which can easily lead to interface failure. However, in Example 2 of this application, a three-dimensional porous Cu-Al alloy current collector provides ample buffer space, and the LiAl alloy layer formed by Al and lithium enhances the interfacial bonding. Compared to Comparative Example 2 (initial coulombic efficiency of 67.0%), Example 1 achieves an initial coulombic efficiency of 82.5%, a cycle life extension of more than three times, and a significant reduction in anode thickness expansion rate. It is evident that the pre-replenished lithium current collector provided by this invention can effectively buffer volume expansion, improve initial coulombic efficiency, and its closed porous structure effectively prevents excessive lithium consumption in the early stages of cycling, achieving long-term lithium replenishment.

[0098] Example 3 The method for preparing the pre-replenished lithium current collector provided in this embodiment includes the following steps: (1) Pretreatment: A three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure, having a porosity of 80%, an average pore size of 30 μm, a Young's modulus of 80 GPa, and a thickness of 100 μm, is made of Cu-Si alloy (composed of Cu and Si elements, with Si being the alloying element), wherein the mass fraction of Si element is 5 wt.%. The three-dimensional porous Cu-Si alloy current collector is heated to 250 °C in an argon glove box to remove adsorbed water and oxygen from the surface, thus obtaining the pretreated current collector.

[0099] The three-dimensional porous copper alloy current collector was prepared by a dealloying method. The preparation process is as follows: copper powder and silicon powder were mixed in a mass ratio of 7:3 and pressed into a block. Then, the block was melted into a melt using an electromagnetic high-frequency heating furnace. The temperature was controlled at 1400℃ and held for 30 minutes to allow the elements to diffuse fully. The melt was then cooled to room temperature. The resulting alloy ingot was rolled into an alloy foil with a thickness of 60μm using a rolling mill. The foil was then immersed and etched with a 25% hydrofluoric acid solution for 5 hours to obtain the three-dimensional porous copper alloy current collector.

[0100] (2) Lithium filling: Under an argon atmosphere, the pretreated current collector is immersed in molten lithium metal at a temperature of 280°C using the fused deposition method. The molten lithium metal is held for 60 seconds and the capillary action is used to draw the molten lithium metal into the pores of the current collector. After removal, it is cooled to room temperature (25°C) to obtain a lithium-filled composite material.

[0101] (3) Pore sealing: The lithium-filled composite material obtained above is rolled at 120°C, wherein the linear pressure of the rolling is 180 N / cm, so that the surface pores are closed. After the rolling, the porosity of the three-dimensional porous copper alloy current collector is reduced to 15%, that is, the porosity of the pre-filled lithium current collector is 15%.

[0102] The pre-filled lithium current collector prepared in this embodiment includes a three-dimensional porous copper alloy current collector and metallic lithium filled and sealed therein, and the metallic lithium and the three-dimensional porous copper alloy current collector are separated by an in-situ formed lithium-alloy element intermetallic compound layer (Li). x Si).

[0103] The pre-filled lithium current collector prepared in this embodiment is directly used as the negative electrode, and the negative electrode is assembled into an all-solid-state battery according to the following method: Positive electrode: high-nickel ternary material (LiNi 0.9 Mn 0.05 Co 0.05 O2 (NMC90) is combined with a sulfide electrolyte (Li6PS5Cl) in a mass ratio of 8:2, with a positive electrode loading of 5.0 mAh / cm³. 2Electrolyte layer: 30 μm thick, formed by pressing sulfide electrolyte (Li6PS5Cl) powder. The positive electrode, electrolyte layer, and negative electrode were sequentially stacked using a dry process, cold-pressed under 250 MPa pressure, and then encapsulated in a coin cell for testing. The test results are shown in Table 3.

[0104] Comparative Example 3 The preparation method of the pre-replenished lithium current collector provided in this comparative example is as follows: the lithium metal foil is directly bonded to the surface of the copper foil by rolling through a physical pressing method, that is, direct lithium pressing and replenishment.

[0105] Using the pre-replenished lithium current collector of this comparative example, an all-solid-state battery was assembled according to the method of Example 3, and its electrochemical performance was tested using the test parameters of Example 3. The test results are shown in Table 3.

[0106] Table 3 Electrochemical performance test results of the batteries in Example 3 and Comparative Example 3

[0107] The lithium metal anode and sulfide electrolyte interface exhibit severe side reactions and are prone to dendrite growth. However, the three-dimensional porous Cu-Si alloy current collector used in Example 3 serves as the anode and plays the following roles through the following mechanisms: (1) Interface isolation: After the pores are sealed, the Cu-Si alloy framework and dense surface layer are in contact with the electrolyte, rather than highly active lithium, which significantly suppresses side reactions; (2) Dendrite suppression: The three-dimensional structure homogenizes the current density, and the lithium-affinity alloy layer formed by Si and lithium induces uniform lithium deposition; (3) Slow-release effect: Lithium in the sealed pores is slowly released through the alloy layer during cycling, avoiding excessive local consumption of lithium. Therefore, compared with Comparative Example 3, the cycle life of the battery in Example 3 is extended from about 150 cycles (capacity retention rate of 80%) to more than 800 cycles, the cycle performance is significantly improved, the critical current density is increased by 3 times, and the interface impedance increases slowly.

[0108] Example 4 The preparation method of the pre-replenished lithium current collector provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), a three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure and a Young's modulus of 115 GPa is used (its porosity, average pore size and thickness are the same as in Example 1). Its material is Cu-Zn alloy (i.e., the alloy element is Zn), and the mass fraction of Zn element is 10 wt.%.

[0109] Using the pre-replenished lithium current collector prepared in this embodiment, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 1, and their electrochemical performance was tested using the test parameters of Example 1. The test results are shown in Table 4.

[0110] Example 5 The preparation method of the pre-replenished lithium current collector provided in this embodiment is basically the same as that in Example 1. The difference is that in step (1), a three-dimensional porous copper alloy current collector with a three-dimensional interconnected pore structure and a Young's modulus of 105 GPa is used (its porosity, average pore size and thickness are the same as in Example 1). Its material is Cu-Mg alloy (i.e., the alloy element is Mg), and the mass fraction of Mg element is 15 wt.%.

[0111] Using the pre-replenished lithium current collector prepared in this embodiment, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 1, and their electrochemical performance was tested using the test parameters of Example 1. The test results are shown in Table 4.

[0112] Comparative Example 4 The preparation method of the pre-replenished lithium current collector provided in this comparative example is basically the same as that in Example 1. The difference is that in step (1), a three-dimensional porous copper current collector with a three-dimensional interconnected pore structure and a Young's modulus of 120 GPa is used (its porosity, average pore size and thickness are the same as those in Example 1), and its material is metal Cu (i.e. copper element).

[0113] Using the pre-replenished lithium current collector prepared in this comparative example, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 1, and their electrochemical performance was tested using the test parameters of Example 1. The test results are shown in Table 4.

[0114] Comparative Example 5 The preparation method of the pre-replenished lithium current collector provided in this comparative example is basically the same as that in Example 1, except that step (3) is omitted, i.e., pore sealing is not performed.

[0115] Using the pre-replenished lithium current collector prepared in this comparative example, a negative electrode and an all-solid-state battery were fabricated according to the method of Example 1, and their electrochemical performance was tested using the test parameters of Example 1. The test results are shown in Table 4.

[0116] Table 4 Electrochemical performance test results

[0117] Comparing Example 1 and Comparative Example 4 reveals that Comparative Example 4, due to the use of elemental copper as the three-dimensional porous copper current collector without the addition of alloying elements capable of alloying with lithium, exhibits a more intense interfacial reaction between the negative electrode and the current collector. This results in a lower initial coulombic efficiency, increased interfacial impedance, and a simultaneous decrease in cycle retention and rate performance. Without alloying elements, lithium reacts rapidly with silicon in the negative electrode, causing a large amount of lithium to be embedded in the negative electrode layer within a short time. This enhances reactivity and intensifies side reactions at the interface, leading to increased interfacial impedance. Furthermore, during long cycles, lithium is consumed, making slow lithium replenishment impossible, resulting in rapid cycle decay.

[0118] Comparing Example 1 and Comparative Example 5 reveals that Comparative Example 5, lacking pore sealing, suffers from reduced cycle retention and rate performance. Without pore sealing, lithium source release is uncontrollable: the directly pressed-in lithium metal participates in the reaction in large quantities during the initial cycle, resulting in overly concentrated lithium source release. This makes it difficult to slowly and continuously replenish active lithium during long cycles, leading to a significant decrease in replenishment efficiency with each cycle. Furthermore, interfacial side reactions are exacerbated: a large amount of lithium metal is directly exposed at the negative electrode / electrolyte interface, easily reacting with the solid electrolyte to generate high-resistivity interfacial byproducts, which in turn increases battery polarization, reducing rate performance and cycle life. Additionally, structural adaptability is poor: the rigid pressing method cannot adapt to the volume changes of the negative electrode during cycling, and interfacial delamination easily occurs between the replenishment layer and the negative electrode body, further deteriorating the interfacial contact.

[0119] As can be seen, the present invention achieves long-term lithium replenishment, significantly reduces interfacial side reactions, enhances the stability of the negative electrode and the interfacial compatibility, and improves the electrochemical performance of the battery by filling the pores with metallic lithium and sealing them, and by utilizing the alloying effect of lithium with alloying elements to form a lithium-alloy interface layer.

[0120] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A pre-replenished lithium current collector, characterized in that, It is obtained from lithium metal and a three-dimensional porous copper alloy current collector with a three-dimensional interconnected hole structure; The three-dimensional porous copper alloy current collector is mainly composed of copper and alloying elements that can undergo alloying reactions with lithium. The lithium metal fills and seals the pores of the three-dimensional porous copper alloy current collector, and the lithium metal and the three-dimensional porous copper alloy current collector are in-situ formed lithium-alloy element intermetallic compound layers.

2. The pre-replenished lithium current collector according to claim 1, characterized in that, At least one of the following conditions must be met: (1) Before the filling, the porosity of the three-dimensional porous copper alloy current collector is 40%~85% and the average pore size of the three-dimensional porous copper alloy current collector is 5μm~50μm; (2) After the filling and sealing, the porosity of the pre-filled lithium current collector is 5%~20%; (3) Before the filling, the Young's modulus of the three-dimensional porous copper alloy current collector is ≥120GPa.

3. The pre-replenished lithium current collector according to claim 1, characterized in that, The alloying elements include one or more of Sn, Si, Al, Zn and Mg; And / or, the mass fraction of the alloying element in the three-dimensional porous copper alloy current collector is 1% to 15%.

4. The method for preparing the pre-replenished lithium current collector according to any one of claims 1 to 3, characterized in that, Includes the following steps: Lithium-filled composite materials are obtained by filling the pores of a three-dimensional porous copper alloy current collector with metallic lithium using either fused deposition or hot rolling. The lithium-filled composite material is rolled to form the lithium metal within the pores.

5. The method for preparing the pre-replenished lithium current collector according to claim 4, characterized in that, The fused deposition method specifically includes the following steps: under an inert atmosphere, the three-dimensional porous copper alloy current collector is immersed in molten lithium metal, and the molten lithium metal is drawn into the pores of the three-dimensional porous copper alloy current collector by capillary force. And / or, the hot rolling method specifically includes the following steps: placing a lithium metal foil on one or both sides of the three-dimensional porous copper alloy current collector, and pressing the lithium metal foil into the pores of the three-dimensional porous copper alloy current collector by heating and rolling; wherein, the temperature of the heating and rolling is 100℃~200℃, and the linear pressure of the heating and rolling is 50N / cm~300N / cm.

6. The method for preparing the pre-replenished lithium current collector according to claim 4, characterized in that, Prior to the filling, the three-dimensional porous copper alloy current collector undergoes pretreatment, which includes heating under inert gas protection.

7. The method for preparing the pre-replenished lithium current collector according to claim 4, characterized in that, The temperature of the roll forming is 20~150℃, and the linear pressure of the roll forming is 50N / cm~300N / cm; And / or, after the roll forming, the porosity of the three-dimensional porous copper alloy current collector is reduced to 5%~20%.

8. The method for preparing the pre-replenished lithium current collector according to claim 4, characterized in that, The three-dimensional porous copper alloy current collector is prepared by template method, dealloying method or foam metal electrodeposition method.

9. A negative electrode, characterized in that, The pre-replenished lithium current collector as described in any one of claims 1 to 3 is used directly as the negative electrode, or it is composed of the pre-replenished lithium current collector as described in any one of claims 1 to 3 and a negative electrode active material layer loaded on the surface of the pre-replenished lithium current collector.

10. An all-solid-state battery, characterized in that, It includes the negative electrode as described in claim 9, as well as a solid electrolyte layer and a positive electrode.

Images