Solid-state lithium metal battery cell with multiple interface film layers and method of making

Abstract

The application discloses a negative electrode-free solid-state lithium metal battery cell with multiple interface film layers and a preparation method. The battery cell includes a first state and a second state; in the first state, the negative electrode tab includes a negative electrode current collector and an artificial interface modification layer, the artificial interface modification layer includes a lithiumophilic metal layer, a lithiumophilic metal compound layer located on the side of the lithiumophilic metal layer away from the negative electrode current collector, and an inorganic lithium ion conductor layer located on the side of the lithiumophilic metal compound layer away from the negative electrode current collector; in the second state, the negative electrode tab includes a negative electrode current collector and an interface layer, the interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative electrode current collector, and an inorganic lithium ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative electrode current collector; wherein M is a lithiumophilic metal. The battery cell can inhibit lithium dendrite growth and interface side reactions and reduce interface impedance, and has good cycle performance and safety performance.

Description

Technical Field

[0001] This application belongs to the field of battery technology, and in particular relates to a negative electrode-free solid lithium metal battery cell with multiple interface films and its preparation method. Background Technology

[0002] Lithium metal possesses an extremely low electrode potential (-3.04 V vs. standard hydrogen electrode) and an extremely high theoretical specific capacity (3860 mAh g⁻¹). -1 It is an ideal anode material for next-generation high-energy-density lithium metal batteries.

[0003] Solid-state lithium metal batteries have become the core development direction of next-generation power batteries due to their high energy density and intrinsic safety. Among them, the negative electrode-free solid-state lithium metal battery does not require the pre-storage of metallic lithium during the manufacturing process. It achieves the negative electrode function through "current collector + in-situ lithium deposition". Compared with traditional batteries containing excess lithium, the energy density can be increased by more than 30%, while reducing costs and safety risks, and has significant industrialization potential.

[0004] However, during the operation of a cathodeless solid-state lithium metal batteries, the in-situ deposited lithium metal, due to its high reactivity, is prone to irreversible side reactions with the electrolyte, generating products with low ionic conductivity, which leads to an increase in interfacial impedance. In addition, due to its lack of a "host", lithium metal is prone to uneven deposition during charging and discharging, which can easily form lithium dendrites that pierce the electrolyte layer, causing short circuits or even thermal runaway in battery cells. Furthermore, the lithium loss caused by lithium dendrite growth and interfacial side reactions can also rapidly lead to battery capacity decay, thereby reducing the cycle performance of battery cells. Summary of the Invention

[0005] This application provides a negative electrode-free solid lithium metal battery cell with multiple interface films and its preparation method. The negative electrode-free solid lithium metal battery cell can suppress lithium dendrite growth and interfacial side reactions and reduce interfacial impedance, and has good cycle performance and safety performance.

[0006] The first aspect of this application provides a non-negative electrode solid lithium metal battery cell with multiple interface films, including a positive electrode, a negative electrode and a solid electrolyte layer, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode. A cathode-free solid-state lithium metal battery cell includes a first state and a second state; In the first state, the negative electrode includes a negative current collector and an artificial interface modification layer located on at least one side of the negative current collector. The artificial interface modification layer includes a lithium-loving metal layer, a lithium-loving metal compound layer located on the side of the lithium-loving metal layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-loving metal compound layer away from the negative current collector. The lithium-loving metal compound includes at least one of lithium-loving metal nitride and lithium-loving metal halide. In the second state, the negative electrode includes a negative current collector and an interface layer located on at least one side of the negative current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative current collector. Wherein, M is a lithium-philic metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

[0007] During the first charge and discharge process, lithium ions in a negative electrode-free solid-state lithium metal battery will deposit lithium metal on the negative electrode side, which can then react in situ with the lithiophilic metal layer and lithiophilic metal compound layer in the artificial interface modification layer to generate an interface layer including a Li-M alloy layer and a Li-M alloy-lithium-containing compound layer, thus changing the negative electrode-free solid-state lithium metal battery cell from the first state to the second state.

[0008] Based on this, since lithium halides and / or lithium nitrides in the Li-M alloy-lithium compound layer have high lithium-ion conductivity and almost no electronic conductivity, they can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This effectively reduces the ion transport impedance at the interface, and thus effectively avoids the current density concentration phenomenon caused by ion transport obstruction during the deposition of metallic lithium. This helps to reduce lithium dendrite formation and capacity decay of battery cells, and improves the cycle performance and safety performance of battery cells.

[0009] Furthermore, since the Li-M alloy phase contains a lithium-loving metal, it helps to provide lithium nucleation and growth sites while providing electrons, thereby controlling lithium deposition to occur on the side of the interface layer near the negative electrode current collector. This effectively avoids direct contact between metallic lithium and the electrolyte, thus avoiding the increase in interface impedance and capacity decay caused by side reactions, and improving the cycle performance of the battery cell.

[0010] Furthermore, the inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium compound layer away from the negative electrode current collector can supplement the inorganic components in the SEI during the process of the negative electrode-free solid lithium metal battery cell changing from the first state to the second state. This can effectively improve the mechanical stability of the SEI, reduce the risk of severe lithium dendrite growth during long-term cycling, and further improve the cycle performance of the battery cell.

[0011] Furthermore, the Li-M alloy-lithium compound layer is a composite structure composed of Li-M alloy and lithium compounds including lithium nitride and / or lithium halide. This means that the composite structure can form a continuous transition interface between the Li-M alloy layer and the inorganic lithium-ion conductor layer. This helps to mitigate interface layer stress under volume fluctuations caused by repeated lithium deposition / stripping, reduces the probability of void formation in the interface layer, and enables each layer in the interface layer to maintain a more stable solid-solid bond. This further reduces local current density fluctuations and interface polarization, improving the cycle performance and safety performance of the battery cell.

[0012] In some embodiments, the thickness of the lithium-loving metal layer is 200 nm to 300 nm.

[0013] In some embodiments, the thickness of the lithium-loving metal compound layer is 100 nm to 200 nm.

[0014] In some implementations, the thickness of the inorganic lithium-ion conductor layer is 50 nm to 150 nm.

[0015] By controlling the thicknesses of the lithiophilic metal layer, the lithiophilic metal compound layer, and the inorganic lithium-ion conductor layer respectively, it is beneficial to control the thickness of the interface layer generated after conversion. This helps to ensure continuous coverage and functional integrity while avoiding the increase in the length of the interface ion transport path and the increase in polarization caused by the thickness of the interface layer. It can also take into account the stability of the interface structure and the volume strain buffering capacity during activation and cycling.

[0016] In some embodiments, the lithium-loving metal includes one or more of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth.

[0017] By employing one or more lithium-loving metals from magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth, it is helpful to reduce the nucleation overpotential of lithium on the current collector surface and provide a uniform and continuous lithium-loving substrate, so that lithium preferentially nucleates on the side closer to the current collector, effectively avoiding direct contact between metallic lithium and electrolyte, thereby avoiding the increase in interfacial impedance and capacity decay caused by side reactions, and improving the cycle performance of battery cells.

[0018] In some embodiments, the lithium-loving metal nitride includes one or more of magnesium nitride, zinc nitride, tin nitride, aluminum nitride, gallium nitride, germanium nitride, indium nitride, and bismuth nitride.

[0019] One or more nitrides, such as magnesium nitride, zinc nitride, tin nitride, aluminum nitride, gallium nitride, germanium nitride, indium nitride, and bismuth nitride, have high lithium-ion conductivity and almost no electronic conductivity. They can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This helps to reduce lithium dendrite formation and capacity decay of individual cells, and improves the cycle performance and safety performance of individual cells.

[0020] In some embodiments, the lithium-loving metal halide includes one or more halides of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth.

[0021] One or more halides of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth have high lithium-ion conductivity and almost no electronic conductivity, which can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This helps to reduce lithium dendrite formation and capacity decay of individual cells, and improves the cycle performance and safety performance of individual cells.

[0022] In some embodiments, the inorganic lithium-ion conductor includes LiF, Li3N, and Li x PO y N z One or more of the following, wherein 2.0≤x≤3.0, 3.0≤y≤4.0, and 0.1≤z≤1.5.

[0023] Inorganic lithium-ion conductors include LiF, Li3N, and Li x PO y N z One or more of these can help replenish the inorganic components in the SEI during the transition from the first state to the second state of the electrodeless solid lithium metal battery cell, effectively improving the mechanical stability of the SEI, reducing the risk of severe lithium dendrite growth during long-term cycling, and further improving the cycle performance of the battery cell.

[0024] In some implementations, the thickness of the interface layer is 200 nm to 500 nm.

[0025] Controlling the thickness of the interface layer to 200nm–500nm helps to avoid the adverse effects of an interface layer that is too thin or too thick on the cycle performance of the battery cells.

[0026] In some implementations, the Young's modulus of the interface layer is 30 GPa to 40 GPa.

[0027] By controlling the Young's modulus of the interface layer to be 30 GPa to 40 GPa, the interface layer can have good mechanical properties and structural stability, effectively resist the volume fluctuations caused by repeated lithium deposition / stripping, reduce the risk of lithium dendrites piercing the solid electrolyte layer, and further improve the safety performance and interface stability of the battery cell.

[0028] In some embodiments, the activation energy for lithium ion migration in the interface layer is 10 kJ / mol. -1 ~30kJmol -1 .

[0029] Generally, the lower the activation energy for lithium ion migration in the interface layer, the higher the lithium ion migration rate. The activation energy for lithium ion migration in the interface layer is controlled at 10 kJ / mol. -1 ~30kJmol -1 This helps maintain high lithium-ion transport performance at the interface layer, thereby avoiding current density concentration caused by ion transport obstruction during lithium metal deposition. It also helps reduce lithium dendrite formation and capacity decay of individual cells, improving the cycle performance and safety of individual cells.

[0030] In some embodiments, the mass fraction of lithium compound in the interface layer is 21% to 34%.

[0031] In some embodiments, the mass fraction of the inorganic lithium-ion conductor in the interface layer is 12% to 20%.

[0032] In some embodiments, the mass fraction of the Li-M alloy in the interface layer is 46% to 67%.

[0033] By controlling the mass fraction of lithium compounds in the interface layer to be 21%–34%, the mass fraction of inorganic lithium-ion conductors to be 12%–20%, and the mass fraction of Li-M alloys to be 46%–67%, a stable lithium-ion transport network can be formed, effectively reducing the ion transport impedance at the interface and improving the cycle performance and safety performance of the battery cell.

[0034] In some embodiments, the solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer-based solid electrolytes, preferably, the solid electrolyte includes a polymer-based solid electrolyte.

[0035] By controlling the matching settings between the interface layer and the polymer-based solid electrolyte, it is possible to introduce inorganic fast ion conductor components into the interface layer while maintaining solid-solid contact flexibility, thus balancing interface stability and transport kinetic advantages.

[0036] In some embodiments, the sulfide solid electrolyte includes Li 10 GeP2S 12The electrolyte is one or more of the following: a solid electrolyte and a sulfide argyrodite electrolyte, Li6PS5X, wherein X is any one of Cl, Br and I, and preferably, the sulfide solid electrolyte is Li6PS5Cl.

[0037] In some embodiments, the halide solid electrolyte includes one or more of ternary halide Li-MX type electrolyte and halide lithium ore type electrolyte Li3EX6, wherein E is any one of Y, Sc, In, Er, Zr, and X is any one of Cl, Br, and I.

[0038] In some embodiments, the oxide solid electrolyte includes a NASICON-type electrolyte Li. 1+t A t Ge 2-t (PO4)3 and Garnet-type electrolyte Li7La3Zr2O 12 One or more of the following, where 0≤t≤0.8, and A is any one of Al and Ga.

[0039] In some embodiments, the polymer-based solid electrolyte includes one or more of the following: polyethylene oxide-based polymer electrolyte systems, polycarbonate-based polymer electrolyte systems, polyvinylidene fluoride-hexafluoropropylene copolymer-based polymer electrolyte systems, and polyacrylonitrile-based polymer electrolyte systems.

[0040] A second aspect of this application provides a method for preparing a negative electrode-free solid-state lithium metal battery cell with multiple interface films, comprising: Provide negative electrode current collector; A lithium-loving metal is deposited on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer; At least one of a lithium-loving metal nitride and a lithium-loving metal halide is deposited on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. An inorganic lithium-ion conductor is deposited on the side of the lithium-ion metal compound layer away from the negative electrode current collector to obtain a negative electrode sheet containing an artificial interface modification layer. The artificial interface modification layer includes a lithium-ion metal layer, a lithium-ion metal compound layer located on the side of the lithium-ion metal layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-ion metal compound layer away from the negative electrode current collector. The first electrodeless solid lithium metal battery cell was obtained by assembling a positive electrode, a solid electrolyte layer, and a negative electrode containing an artificial interface modification layer.

[0041] In some implementations, it also includes: The first electrodeless solid-state lithium metal battery cell is subjected to a formation process so that the artificial interface modification layer reacts in situ with the electrochemically deposited lithium metal to obtain the second electrodeless solid-state lithium metal battery cell. In the second negative electrode-free solid lithium metal battery cell, the negative electrode sheet includes a negative electrode current collector and an interface layer located on at least one side of the negative electrode current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative electrode current collector. Wherein, M is a lithium-loving metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

[0042] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into a cathode magnetic filter vacuum arc deposition apparatus containing a negative electrode current collector with a lithium-loving metal layer to deposit a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the cathode magnetic filtering vacuum arc deposition equipment is a lithium-philic metal target; optionally, the background vacuum level of the cathode magnetic filtering vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 -3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 °C to 30 °C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 °C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 3 min to 10 min; Optionally, the nitrogen flux of the cathode magnetic filter vacuum arc deposition equipment is 30 sccm to 80 sccm.

[0043] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-loving metal layer, or nitrogen gas and inert gas are introduced into a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-loving metal layer, to deposit a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the magnetron sputtering equipment is a lithium-philic metal target; optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the inert gas is argon, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 15min~25min; optionally, the nitrogen flux of the magnetron sputtering equipment is 40sccm-80sccm; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W.

[0044] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes: In the case of depositing only lithium-loving metal nitrides, a lithium-loving metal nitride target material is deposited under inert atmosphere conditions by controlling a magnetron sputtering device containing a lithium-loving metal current collector to deposit lithium-loving metal nitrides, thereby obtaining a lithium-loving metal current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 15min~25min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0045] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes: In the case of depositing only lithium-loving metal halides, a lithium-loving metal halide target material is deposited under inert atmosphere conditions by controlling a magnetron sputtering device containing a lithium-loving metal current collector to deposit lithium-loving metal halide target material, thereby obtaining a lithium-loving metal current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 25min~40min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0046] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes: In the case of depositing lithium-loving metal nitrides and lithium-loving metal halides, a magnetron sputtering apparatus containing a lithium-loving metal current collector is used to co-deposit lithium-loving metal halide targets and lithium-loving metal nitride targets under inert atmosphere conditions to obtain a lithium-loving metal current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 25min~40min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0047] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-philic metal layer by depositing a lithium-philic metal on at least one side of the negative electrode current collector includes: A lithium-loving metal target is deposited by controlling a magnetron sputtering device containing a negative electrode current collector under inert atmosphere conditions to obtain a negative electrode current collector containing a lithium-loving metal layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 20min~60min; optionally, the deposition power of the magnetron sputtering equipment is 100W~150W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0048] In some embodiments, a method for obtaining a negative electrode current collector containing a lithium-philic metal layer by depositing a lithium-philic metal on at least one side of the negative electrode current collector includes: A negative electrode current collector containing a lithium-loving metal layer is obtained by controlling a cathode magnetic filter vacuum arc deposition equipment with a negative electrode current collector to deposit a lithium-loving metal target. Optionally, the background vacuum level of the cathode magnetic filter vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 - 3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 ° C to 30 ° C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 ° C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 5 min to 15 min.

[0049] In some embodiments, a method for depositing an inorganic lithium-ion conductor on the side of a lithium-philic metal compound layer away from the negative electrode current collector to obtain a negative electrode sheet containing an artificial interface modification layer includes: In an inert atmosphere, an inorganic lithium-ion conductor target is deposited using a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-philic metal layer and a lithium-philic metal compound layer, to obtain a negative electrode sheet with an artificial interface modification layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 10min~20min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0050] A third aspect of this application provides a battery device comprising a negative electrode-free solid lithium metal battery cell of the first aspect, or a negative electrode-free solid lithium metal battery cell prepared by the method of the second aspect.

[0051] The fourth aspect of this application provides an electrical device comprising a negative electrode-free solid lithium metal battery cell of the first aspect, or a negative electrode-free solid lithium metal battery cell prepared by the method of the second aspect, or a battery device of the third aspect. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 This is a schematic diagram of the process for preparing an artificial interface modification layer using a physical vapor deposition method with the BNU100 multi-functional deposition equipment in Embodiment 1 of this application; Figure 2 These are SEM images and elemental distribution diagrams of the cross-section of the negative electrode sheet obtained in Embodiment 1 of this application; Figure 3 This is a schematic diagram of XPS signals after the deposition of Mg3N2 and LiF layers in Example 1 of this application; Figure 4 In this embodiment of the application, the circulating current density is 0.2 mA*cm. -2 Single deposition / stripping capacity: 0.2 mAh*cm³ -2 Schematic diagram of the cycling performance of Li|Mg-Mg3N2-LiF@Cu half-cell and Li|Cu coin cell under the specified conditions; Figure 5 In the embodiments of this application, the cyclic current density is 0.5 mA*cm. -2 Single deposition / stripping capacity: 0.5 mAh*cm -2 Schematic diagram of the cycling performance of the Li|Mg-Mg3N2-LiF@Cu half-cell and the Li|Cu half-cell; Figure 6 This is a schematic diagram of the cycle performance of LFP|Mg-Mg3N2-LiF@Cu coin cell and LFP|Cu coin cell under the LFP cathode configuration in the embodiments of this application under the condition of 0.1C cycle rate; Figure 7 This is a schematic diagram of the cycle performance of LFP|Mg-Mg3N2-LiF@Cu pouch cell and LFP|Cu pouch cell under the LFP cathode configuration in the embodiments of this application under the condition of 0.1C cycle rate; Figure 8 This is a schematic diagram of the cycle performance of the NCM811|Mg-Mg3N2-LiF@Cu full cell and the NCM811|Cu full cell under the NCM811 cathode configuration in the embodiments of this application under the condition of 0.1C cycle rate. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] The embodiments of this application will be described in detail below. These embodiments should not be construed as limiting the scope of this application.

[0056] As used in this application, the terms “comprising,” “containing,” and “including” are used in their open, non-restrictive sense.

[0057] Additionally, quantities, ratios, and other numerical values ​​are sometimes presented in range format in this document. It should be understood that such range format is for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​explicitly specified as range limits, but also all individual numerical values ​​or subranges covered within the range, as if each numerical value and subrange were explicitly specified.

[0058] In the detailed description and claims, a list of items connected by the terms "one or more of," "one or more of," "at least one of," or other similar terms can mean any combination of the listed items. For example, if items A and B are listed, then the phrase "at least one of A or B" means only A; only B; or A and B. In another example, if items A, B, and C are listed, then the phrase "at least one of A, B, or C" means only A; or only B; only C; A and B (excluding C); A and C (excluding B); B and C (excluding A); or all of A, B, and C. Item A may contain a single element or multiple elements. Item B may contain a single element or multiple elements. Item C may contain a single element or multiple elements.

[0059] A negative electrode-free battery cell typically refers to a battery cell in which no negative electrode active material layer is actively formed on the negative electrode side during the battery cell manufacturing process. For example, the negative electrode active material layer is not formed at the negative electrode through coating or deposition processes, or it is formed from a carbonaceous active material layer. During the first charge, ions gain electrons on the negative electrode side and deposit metal on the surface of the negative electrode current collector. During discharge, the metal can be converted back into ions and return to the positive electrode, achieving cyclic charging and discharging. Compared to other battery cells, a negative electrode-free battery cell can achieve a higher energy density due to the absence of a negative electrode active material layer. In some embodiments, to improve battery cell performance, some conventional materials that can be used as negative electrode active materials, such as carbon materials, can also be placed on the negative electrode side of the negative electrode-free battery cell. Although these materials have a certain capacity, because their content is small and they are not used as the main negative electrode active material in the battery cell, the battery cell constructed in this way can still be considered a negative electrode-free battery cell.

[0060] Lithium metal possesses an extremely low electrode potential (-3.04 V vs. standard hydrogen electrode) and an extremely high theoretical specific capacity (3860 mAh g⁻¹). -1 Solid-state lithium metal (SLM) is an ideal anode material for next-generation high-energy-density lithium metal batteries. Due to its high energy density and inherent safety, SLM has become a core development direction for next-generation power batteries. Among them, anode-free SLM batteries do not require pre-storing lithium metal during the manufacturing process. They can achieve the anode function through a "current collector + in-situ lithium deposition" method. Compared to traditional batteries containing excess lithium, their energy density can be increased by more than 30%, while simultaneously reducing costs and safety risks, demonstrating significant industrialization potential.

[0061] However, the commercialization of electrodeless solid-state lithium metal batteries faces the following core challenges: 1) Interface contact and uneven current problem: Copper current collector is the core conductive substrate on the negative electrode side, but the interface contact between copper and solid electrolyte (such as LPSCl, LLZO, etc.) is poor, resulting in uneven current distribution, which can easily cause local lithium metal deposition, leading to high polarization or even lithium dendrite problems. 2) Severe interfacial side reactions: Sulfide electrolytes typically have an electrochemical window <4.0 V, which is narrow. In-situ deposited lithium metal easily reacts with the electrolyte to generate low ionic conductivity products such as Li₂S and Li₃P, leading to an increase in interfacial impedance. Halide electrolytes (such as Li₃YCl₆) also face the risk of being reduced by lithium metal, resulting in deterioration of interfacial composition and structure. Some oxide electrolytes (such as LLZO) may also be reduced under local high overpotentials, forming unstable interfacial phases. Some polymer electrolytes may undergo chemical decomposition on the lithium metal surface. These irreversible side reactions continuously consume active lithium and electrolyte, leading to a continuous increase in interfacial impedance and rapid capacity decay. 3) Lithium loss and lifespan limitations: Without a negative electrode system, there is no surplus lithium reserve. Lithium loss caused by lithium dendrite growth and interfacial side reactions will quickly lead to battery capacity decay. Batteries assembled with traditional copper current collectors often experience short circuits in the first cycle or failure within 5 cycles.

[0062] 4) Lack of effective ion / electron transport control: An ideal anode interface should be able to simultaneously achieve rapid lithium-ion transport and controllable electron transport to guide uniform lithium deposition and suppress dendrite formation. The interface layer in related technologies often fails to meet multiple requirements, including ionic conductivity, electronic insulation, mechanical strength, and chemical stability.

[0063] Currently, although some studies have attempted to address the aforementioned issues by introducing artificial interface layers, most methods have significant limitations. For example, the fabrication process is complex and difficult to scale up, and the introduced interface layer cannot simultaneously achieve key properties such as ionic conductivity, electronic conductivity, and mechanical strength, making it difficult to simultaneously achieve the multiple objectives of promoting uniform lithium deposition, suppressing dendrites, and blocking side reactions. Specifically, related technical solutions often only solve a single problem. For instance, improving interfacial contact by optimizing the electrolyte's mechanical properties or adjusting the surface roughness of the current collector cannot simultaneously meet the three core requirements of "high lithium-ion transport efficiency," "strong lithium dendrite suppression," and "effective isolation of interfacial side reactions." Furthermore, while simply thickening the sulfide electrolyte can improve the battery's resistance to lithium dendrites, it significantly increases the battery's internal resistance. While coating the electrolyte surface with inert layers such as Al2O3 or ZnO can isolate side reactions, it severely sacrifices the advantages of lithium-ion transport kinetics, affecting the battery's cycle performance.

[0064] To address the aforementioned technical problems, this application provides a cathode-free solid lithium metal battery cell with multiple interface films and its preparation method. This cathode-free solid lithium metal battery cell can suppress lithium dendrite growth and interfacial side reactions and reduce interfacial impedance, exhibiting good cycle performance and safety performance.

[0065] The embodiments of this application will be described in detail below.

[0066] The first aspect of this application provides a negative electrode-free solid lithium metal battery cell, including a positive electrode, a negative electrode and a solid electrolyte layer, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode. A cathode-free solid-state lithium metal battery cell includes a first state and a second state; In the first state, the negative electrode includes a negative current collector and an artificial interface modification layer located on at least one side of the negative current collector. The artificial interface modification layer includes a lithium-loving metal layer, a lithium-loving metal compound layer located on the side of the lithium-loving metal layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-loving metal compound layer away from the negative current collector. The lithium-loving metal compound includes at least one of lithium-loving metal nitride and lithium-loving metal halide. In the second state, the negative electrode includes a negative current collector and an interface layer located on at least one side of the negative current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative current collector. Wherein, M is a lithium-philic metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

[0067] In the first state of the electrodeless solid-state lithium metal battery cell, the artificial interface modification layer can act as a chemical barrier layer to block the contact between the negative electrode current collector and the electrolyte, reducing possible side reactions during storage, transportation, and assembly. During the first charge and discharge process of the electrodeless lithium metal battery, lithium ions will deposit on the negative electrode side to form lithium metal. This lithium metal can then react in situ with the lithiophilic metal layer and lithiophilic metal compound layer in the artificial interface modification layer to form an interface layer including a Li-M alloy layer and a Li-M alloy-lithium-containing compound layer, thus transforming the electrodeless solid-state lithium metal battery cell from the first state to the second state.

[0068] Based on this, since lithium halides and / or lithium nitrides in the Li-M alloy-lithium compound layer have high lithium-ion conductivity and almost no electronic conductivity, they can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This effectively reduces the ion transport impedance at the interface, and thus effectively avoids the current density concentration phenomenon caused by ion transport obstruction during the deposition of metallic lithium. This helps to reduce lithium dendrite formation and capacity decay of battery cells, and improves the cycle performance and safety performance of battery cells.

[0069] Furthermore, since the Li-M alloy phase contains a lithium-loving metal, it helps to provide lithium nucleation and growth sites while providing electrons, thereby controlling lithium deposition to occur on the side of the interface layer near the negative electrode current collector. This effectively avoids direct contact between metallic lithium and the electrolyte, thus avoiding the increase in interface impedance and capacity decay caused by side reactions, and improving the cycle performance of the battery cell.

[0070] Furthermore, the inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium compound layer away from the negative electrode current collector can supplement the inorganic components in the SEI during the process of the negative electrode-free solid lithium metal battery cell changing from the first state to the second state. This can effectively improve the mechanical stability of the SEI, reduce the risk of severe lithium dendrite growth during long-term cycling, and further improve the cycle performance of the battery cell.

[0071] Furthermore, the Li-M alloy-lithium compound layer is a composite structure composed of Li-M alloy and lithium compounds including lithium nitride and / or lithium halide. This means that the composite structure can form a continuous transition interface between the Li-M alloy layer and the inorganic lithium-ion conductor layer. This helps to mitigate interface layer stress under volume fluctuations caused by repeated lithium deposition / stripping, reduces the probability of void formation in the interface layer, and enables each layer in the interface layer to maintain a more stable solid-solid bond. This further reduces local current density fluctuations and interface polarization, improving the cycle performance and safety performance of the battery cell.

[0072] In some embodiments, the lithium-containing compound in the Li-M alloy-lithium-containing compound layer is a continuous phase, and the Li-M alloy is dispersed in the lithium-containing compound as a dispersed phase.

[0073] By setting the lithium-containing compound in the Li-M alloy-lithium-containing compound layer as the continuous phase and the Li-M alloy as the dispersed phase dispersed in the lithium-containing compound, the synergistic configuration of "fast ion conductor continuous phase / alloy phase local electron and nucleation sites" can simultaneously ensure rapid ion transport and controlled electron conduction, thereby suppressing dendrites and reducing the risk of side reactions.

[0074] In some embodiments, the thickness of the lithium-loving metal layer is 200nm to 300nm, for example, it can be 200nm, 210nm, 220nm, 230nm, 240nm, 250nm, 260nm, 270nm, 280nm, 290nm, 300nm or any combination of the above values.

[0075] In some embodiments, the thickness of the lithium-loving metal compound layer is 100 nm to 200 nm, for example, it can be 100 nm, 110 nm, 120 nm, 130 nm, 140 nm, 150 nm, 160 nm, 170 nm, 180 nm, 190 nm, 200 nm or any combination of the above values.

[0076] In some embodiments, the thickness of the inorganic lithium-ion conductor layer is 50nm to 150nm, for example, it can be 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm or any combination of the above values.

[0077] By controlling the thicknesses of the lithiophilic metal layer, the lithiophilic metal compound layer, and the inorganic lithium-ion conductor layer respectively, it is beneficial to control the thickness of the interface layer generated after conversion. This helps to ensure continuous coverage and functional integrity while avoiding the increase in the length of the interface ion transport path and the increase in polarization caused by the thickness of the interface layer. It can also take into account the stability of the interface structure and the volume strain buffering capacity during activation and cycling.

[0078] In some embodiments, the lithium-loving metal includes one or more of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth.

[0079] By employing one or more lithium-loving metals from magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth, it is helpful to reduce the nucleation overpotential of lithium on the current collector surface and provide a uniform and continuous lithium-loving substrate, so that lithium preferentially nucleates on the side closer to the current collector, effectively avoiding direct contact between metallic lithium and electrolyte, thereby avoiding the increase in interfacial impedance and capacity decay caused by side reactions, and improving the cycle performance of battery cells.

[0080] In some embodiments, the lithium-loving metal nitride includes one or more of magnesium nitride, zinc nitride, tin nitride, aluminum nitride, gallium nitride, germanium nitride, indium nitride, and bismuth nitride.

[0081] One or more nitrides, such as magnesium nitride, zinc nitride, tin nitride, aluminum nitride, gallium nitride, germanium nitride, indium nitride, and bismuth nitride, have high lithium-ion conductivity and almost no electronic conductivity. They can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This helps to reduce lithium dendrite formation and capacity decay of individual cells, and improves the cycle performance and safety performance of individual cells.

[0082] In some embodiments, the lithium-loving metal halide includes one or more halides of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth.

[0083] One or more halides of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth have high lithium-ion conductivity and almost no electronic conductivity, which can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This helps to reduce lithium dendrite formation and capacity decay of individual cells, and improves the cycle performance and safety performance of individual cells.

[0084] In some embodiments, inorganic lithium-ion conductors include LiF, Li3N, and Li x PO y N z One or more of the following, wherein 2.0≤x≤3.0, 3.0≤y≤4.0, and 0.1≤z≤1.5.

[0085] Inorganic lithium-ion conductors include LiF, Li3N, and Li x PO y N z One or more of these can help replenish the inorganic components in the SEI during the transition from the first state to the second state of the electrodeless solid lithium metal battery cell, effectively improving the mechanical stability of the SEI, reducing the risk of severe lithium dendrite growth during long-term cycling, and further improving the cycle performance of the battery cell.

[0086] In some embodiments, the thickness of the interface layer is 200 nm to 500 nm.

[0087] Controlling the thickness of the interface layer to 200nm–500nm helps to avoid the adverse effects of an interface layer that is too thin or too thick on the cycle performance of the battery cells.

[0088] In some embodiments, the Young's modulus of the interface layer is 30 GPa to 40 GPa, for example, it can be ... or any range of the above values.

[0089] The Young's modulus of the interface layer is 30 GPa to 40 GPa, which enables the interface layer to have good mechanical properties and structural stability. It can effectively resist volume fluctuations caused by repeated lithium deposition / stripping, reduce the risk of lithium dendrites piercing the solid electrolyte layer, and further improve the safety performance and interface stability of the battery cell.

[0090] The Young's modulus of the interface layer can be determined by separating the negative electrode from the battery body, separating the interface layer in the negative electrode, and then testing it using a nanoindenter and atomic force microscope (AFM). The test temperature is 25℃.

[0091] In some embodiments, the activation energy for lithium ion migration in the interface layer is 10 kJ / mol. -1 ~30kJmol -1 .

[0092] Generally, the lower the activation energy for lithium ion migration in the interface layer, the higher the lithium ion migration rate. The activation energy for lithium ion migration in the interface layer is controlled at 10 kJ / mol. -1 ~30kJmol -1 This helps maintain high lithium-ion transport performance at the interface layer, thereby avoiding current density concentration caused by ion transport obstruction during lithium metal deposition. It also helps reduce lithium dendrite formation and capacity decay of individual cells, improving the cycle performance and safety of individual cells.

[0093] The activation energy for lithium-ion migration in the interface layer can be determined by electrochemical impedance spectroscopy combined with Arrhenius equation fitting. Specifically: First, a symmetrical cell with an interface layer can be prepared, and then the symmetrical cell is placed in a series of isothermal environments at different temperatures (e.g., 25°C to 80°C) for electrochemical impedance spectroscopy testing, with a test frequency range of 1 MHz to 0.1 Hz. By fitting the obtained impedance spectrum using an equivalent circuit containing interface resistance units, the interface resistance value at each temperature can be accurately extracted. Subsequently, according to the Arrhenius relation, the activation energy for lithium-ion migration in the interface layer can be obtained by fitting the Arrhenius equation.

[0094] In some embodiments, the mass fraction of lithium compound in the interface layer is 21% to 34%.

[0095] In some embodiments, the mass fraction of the inorganic lithium-ion conductor in the interface layer is 12% to 20%.

[0096] In some embodiments, the mass fraction of Li-M alloy in the interface layer is 46% to 67%.

[0097] By controlling the mass fraction of lithium compounds in the interface layer to be 21%–34%, the mass fraction of inorganic lithium-ion conductors to be 12%–20%, and the mass fraction of Li-M alloys to be 46%–67%, it is helpful to form continuous ion channels in the fast ion conductor phase composed of lithium compounds. At the same time, the alloy phase provides the necessary electrons and nucleation / growth sites without excessively increasing the risk of electron leakage. This confines lithium deposition mainly to the inner side of the interface layer and reduces the direct contact between active lithium and the electrolyte, further suppressing side reactions and lithium loss.

[0098] In some embodiments, the solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer-based solid electrolytes, preferably, the solid electrolyte includes a polymer-based solid electrolyte.

[0099] Polymer solid-state electrolytes (SSEs) exhibit good flexibility and high lithium-ion conductivity, enabling efficient ion migration over a wide temperature range. Compared to sulfide SSEs, SSEs are better suited for large-area thin-film applications and offer superior interfacial compatibility. Furthermore, SSEs demonstrate good chemical interfacial compatibility with lithium halides, effectively reducing interfacial impedance. Combined with the aforementioned interface layer design, the cycle performance and interfacial stability of individual battery cells can be significantly improved while avoiding side reactions between lithium metal and the electrolyte. Through synergy with the interface layer, interfacial ion transport performance can be further optimized, reducing interfacial side reactions and enhancing the lifetime stability of electrodeless solid-state lithium metal battery cells.

[0100] In some embodiments, the sulfide solid electrolyte includes Li 10 GeP2S 12 The electrolyte is one or more of the following: a solid electrolyte and a sulfide argyrodite electrolyte, Li6PS5X, wherein X is any one of Cl, Br and I, and preferably, the sulfide solid electrolyte is Li6PS5Cl.

[0101] The interface layer construction method of this application does not depend on the specific chemical composition of the sulfide solid electrolyte, and is applicable to Li6PS5Cl, Li6PS5Br, and Li 10 GeP2S 12 Typical high-conductivity sulfides are all compatible, making them easy to promote in different systems of electrodeless solid-state lithium batteries.

[0102] In some embodiments, the halide solid electrolyte includes one or more of ternary halide Li-MX type electrolyte and halide lithium ore type electrolyte Li3EX6, wherein E is any one of Y, Sc, In, Er, Zr, and X is any one of Cl, Br, and I.

[0103] In some embodiments, the oxide solid electrolyte includes a NASICON-type electrolyte Li 1+t A t Ge 2-t (PO4)3 and Garnet-type electrolyte Li7La3Zr2O 12 One or more of the following, where 0≤t≤0.8, and A is any one of Al and Ga.

[0104] In some embodiments, the polymer-based solid electrolyte includes one or more of the following: polyethylene oxide-based polymer electrolyte systems, polycarbonate-based polymer electrolyte systems, polyvinylidene fluoride-hexafluoropropylene copolymer-based polymer electrolyte systems, and polyacrylonitrile-based polymer electrolyte systems. This type of electrolyte exhibits good flexibility and interfacial contact with lithium metal, enabling it to synergize with the interfacial layer provided by this invention, further optimizing the battery's interfacial stability and cycle performance.

[0105] Secondly, embodiments of this application provide a method for preparing a negative electrode-free solid-state lithium metal battery cell with multiple interface films, comprising: S101: Provides negative electrode current collector; S102: Deposit a lithium-loving metal on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer; S103: Deposit at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. S104: An inorganic lithium-ion conductor is deposited on the side of the lithium-loving metal compound layer away from the negative electrode current collector to obtain a negative electrode sheet containing an artificial interface modification layer. The artificial interface modification layer includes a lithium-loving metal layer, a lithium-loving metal compound layer located on the side of the lithium-loving metal layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-loving metal compound layer away from the negative electrode current collector. S105: Assemble the positive electrode, solid electrolyte layer and negative electrode containing artificial interface modification layer to obtain the first negative electrode-free solid lithium metal battery cell.

[0106] In some examples, the negative electrode current collector can be cleaned before deposition, for example, by performing ion cleaning, such as argon ion cleaning, on the negative electrode current collector in a vacuum chamber to remove surface contaminants and improve the adhesion and uniformity of subsequent deposited layers.

[0107] In some examples, vacuum deposition processes can be used to deposit the lithiophilic metal layer, the lithiophilic metal compound layer, and the inorganic lithium-ion conductor layer. For instance, cathode magnetic filtering vacuum arc deposition or magnetron sputtering deposition can be employed. This allows for continuous coverage of the lithiophilic metal layer, the lithiophilic metal compound layer, and the inorganic lithium-ion conductor layer at the nanometer thickness scale, improving thickness controllability and contributing to tighter interlayer bonding. This, in turn, enhances the structural stability and repeatability of the artificial interface modification layer.

[0108] In some embodiments, a method for depositing a lithium-philic metal on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-philic metal layer includes: A lithium-loving metal target is deposited by controlling a magnetron sputtering device containing a negative electrode current collector under inert atmosphere conditions to obtain a negative electrode current collector containing a lithium-loving metal layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 20min~60min; optionally, the deposition power of the magnetron sputtering equipment is 100W~150W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0109] In practical applications, magnetron sputtering can be used to deposit lithiophilic metals to obtain a negative electrode current collector containing a lithiophilic metal layer. Specifically, under inert atmosphere conditions, a magnetron sputtering device containing a negative electrode current collector can be used to deposit a lithiophilic metal target, resulting in a negative electrode current collector containing a lithiophilic metal layer. To achieve the desired performance of the lithiophilic metal layer, the base vacuum of the magnetron sputtering device can be set to 9.0 × 10⁻⁶ when depositing the lithiophilic metal. -4 Pa ~ 5.0 × 10 -3 The working pressure is 1Pa~5Pa, the initial temperature is 15℃~30℃, the maximum working temperature is 100℃, the deposition time is 20min~60min, the deposition power is 100W~150W, and the inert atmosphere can be set to argon atmosphere, and the argon flux of the magnetron sputtering equipment can be set to 20sccm~50sccm.

[0110] Therefore, by sputtering a lithiophilic metal target in an inert atmosphere, a pure lithiophilic metal layer is deposited on the surface of the negative electrode current collector. This significantly reduces the nucleation overpotential during subsequent lithium deposition, allowing lithium to nucleate and grow uniformly on the side near the current collector, thereby improving the stability of the negative electrode interface and reducing the risk of dendrite formation.

[0111] In some embodiments, a method for depositing a lithium-philic metal on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-philic metal layer includes: A negative electrode current collector containing a lithium-loving metal layer is obtained by controlling a cathode magnetic filter vacuum arc deposition equipment with a negative electrode current collector to deposit a lithium-loving metal target. Optionally, the background vacuum level of the cathode magnetic filter vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 - 3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 ° C to 30 ° C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 ° C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 5 min to 15 min.

[0112] In practical applications, the deposition of lithiophilic metals can also be achieved directly using a cathode magnetic filter vacuum arc deposition (CMD) system. Specifically, the CMD system, which contains a negative electrode current collector, can be controlled to deposit a lithiophilic metal target, resulting in a negative electrode current collector containing a lithiophilic metal layer. To achieve the desired performance of the lithiophilic metal layer, the background vacuum level of the CMD system can be set to 9.0 × 10⁻⁶ when performing the deposition. -4 Pa ~ 3.0 × 10 -3 The working pressure is 0.01Pa~0.1Pa, the arc current is 80A~120A, the initial temperature is 15℃~30℃, the maximum working temperature is 150℃, and the deposition time is 5min~15min, thereby achieving a good construction of the lithium-friendly metal layer.

[0113] Therefore, by using cathode magnetic filtering vacuum arc technology to deposit lithium-loving metals, a highly dense and strongly adherent lithium-loving metal layer can be rapidly formed on the current collector surface. Due to the high-energy ion beam characteristics of arc deposition, the lithium-loving metal layer has fewer pores and stronger bonding, making it a more effective and uniform nucleation substrate for lithium deposition. Furthermore, it maintains the integrity of the interface structure during cycling, thereby improving interface reliability and battery life.

[0114] In some embodiments, a method for depositing at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer includes: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into a cathode magnetic filter vacuum arc deposition apparatus containing a negative electrode current collector with a lithium-loving metal layer to deposit a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the cathode magnetic filtering vacuum arc deposition equipment is a lithium-philic metal target; optionally, the background vacuum level of the cathode magnetic filtering vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 -3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 °C to 30 °C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 °C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 3 min to 10 min; Optionally, the nitrogen flux of the cathode magnetic filter vacuum arc deposition equipment is 30 sccm to 80 sccm.

[0115] In practical implementation, the deposition of lithium-loving metal nitrides can be achieved by controlling the deposition atmosphere of the vacuum deposition process to be a reactive atmosphere when only lithium-loving metal nitrides are deposited. For example, nitrogen gas can be introduced into a cathode magnetic filter vacuum arc deposition device containing a negative electrode current collector with a lithium-loving metal layer, so that the lithium-loving metal reacts with the nitrogen gas in situ to generate lithium-loving metal nitrides, and a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer is deposited.

[0116] To ensure the generated lithiophilic metal compound layer achieves the desired effect, when depositing lithiophilic metal nitrides using a cathode magnetically filtered vacuum arc deposition (CMA) system with nitrogen purging, the target material used in the CMA system can be set to a lithiophilic metal target, and the background vacuum level of the CMA system can be set to 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 -3 The working pressure is 0.01 Pa to 0.1 Pa, the arc current is 80 A to 120 A, the initial temperature is 15 °C to 30 °C, the maximum working temperature is 150 °C, the deposition time is 3 min to 10 min, and the nitrogen flux is 30 sccm to 80 sccm. This is to achieve the deposition of a lithium-loving metal compound layer.

[0117] Therefore, due to the high-energy ion flow and good film density of arc deposition, this method can prepare a continuous and firmly bonded lithium-loving metal compound layer on the surface of the lithium-loving metal layer, thereby providing a stable and dense basic interface structure for the formation of a uniform Li-M alloy and lithium-containing nitride composite interface in the subsequent electrochemical formation process.

[0118] In some embodiments, a method for depositing at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer includes: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-loving metal layer, or nitrogen gas and inert gas are introduced into a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-loving metal layer, to deposit a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the magnetron sputtering equipment is a lithium-philic metal target; optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the inert gas is argon, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 15min~25min; optionally, the nitrogen flux of the magnetron sputtering equipment is 40sccm-80sccm; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W.

[0119] In practical applications, when only lithium-loving metal nitrides are deposited, magnetron sputtering equipment can also be used to deposit lithium-loving metal nitrides. Specifically, nitrogen gas can be introduced into a magnetron sputtering equipment containing a negative electrode current collector with a lithium-loving metal layer, or nitrogen gas and inert gas can be introduced into a magnetron sputtering equipment containing a negative electrode current collector with a lithium-loving metal layer to deposit a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. That is, nitrogen gas can be further introduced into the deposition atmosphere or a mixture of inert gas and nitrogen gas can be used to achieve reactive sputtering deposition to form a lithium-loving metal nitride layer.

[0120] To ensure the generated lithium-ion metal compound layer achieves the desired effect, the target material used in the magnetron sputtering equipment can be set to a lithium-ion metal target, and the background vacuum level of the magnetron sputtering equipment can be set to 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 The working pressure is 1Pa~5Pa, and the inert gas can be set to argon, with the argon flux of the magnetron sputtering equipment set to 20sccm~50sccm. In addition, the initial temperature of the magnetron sputtering equipment can be set to 15℃~30℃, the maximum working temperature to 100℃, the deposition time to 15min~25min, the nitrogen flux to 40sccm-80sccm, and the deposition power to 80W~100W.

[0121] This enables the stable preparation of lithium-loving metal nitride layers, resulting in a more uniform interfacial chemical composition, which is beneficial for subsequent controllable in-situ reactions with lithium metal and the construction of a uniform composite interfacial structure.

[0122] In some embodiments, a method for depositing at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer includes: In the case of depositing only lithium-loving metal nitrides, a lithium-loving metal nitride target material is deposited under inert atmosphere conditions by controlling a magnetron sputtering device containing a lithium-loving metal current collector to deposit lithium-loving metal nitrides, thereby obtaining a lithium-loving metal current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 15min~25min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0123] In practical implementation, the deposition of lithium-ion metal nitrides can also be achieved by directly depositing lithium-ion metal nitride targets. For example, under inert atmosphere conditions, a magnetron sputtering apparatus containing a lithium-ion metal layer can be used to deposit a lithium-ion metal nitride target while only depositing lithium-ion metal nitrides, resulting in a negative electrode current collector containing both a lithium-ion metal layer and a lithium-ion metal compound layer. In other words, the corresponding lithium-ion metal nitride target can be directly deposited using the radio frequency deposition mode of a magnetron sputtering apparatus.

[0124] To ensure that the deposited lithium-friendly metal compound layer meets the preset performance requirements in terms of thickness, the base vacuum of the magnetron sputtering equipment can be set to 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 The working pressure is 1Pa~5Pa, the initial temperature is 15℃~30℃, the maximum working temperature is 100℃, the deposition time is 15min~25min, and the deposition power is 80W~100W. In addition, the inert atmosphere can be set to argon atmosphere, and the argon flux of the magnetron sputtering equipment can be set to 20sccm~50sccm.

[0125] Therefore, by using a lithium-loving metal nitride target for direct magnetron sputtering in an inert atmosphere, the composition of the deposited film and the target can be kept consistent, avoiding the problem of compositional fluctuations during reactive sputtering. This results in a more uniform and stable lithium-loving metal compound layer, which helps to stably generate lithium-containing nitrides during battery formation and improves the overall uniformity and reliability of the interface.

[0126] In some embodiments, a method for depositing at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer includes: In the case of depositing only lithium-loving metal halides, a lithium-loving metal halide target material is deposited under inert atmosphere conditions by controlling a magnetron sputtering device containing a lithium-loving metal current collector to deposit lithium-loving metal halide target material, thereby obtaining a lithium-loving metal current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 25min~40min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0127] In practical applications, when the lithium-loving metal compound layer includes lithium-loving metal halides, it is no longer suitable to pass halogen gas into a vacuum reaction chamber to achieve the deposition of lithium-loving metal halides. In this case, sputtering deposition is required in the chamber of a magnetron sputtering equipment using a corresponding high-purity lithium-loving metal halide target. For example, when only lithium-loving metal halides are deposited, a lithium-loving metal halide target can be deposited under an inert atmosphere by controlling a magnetron sputtering equipment containing a negative electrode current collector with a lithium-loving metal layer to obtain a negative electrode current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer.

[0128] To ensure that the deposited lithium-friendly metal compound layer meets the preset performance requirements in terms of thickness, the base vacuum of the magnetron sputtering equipment can be set to 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa, working gas pressure is 1Pa~5Pa, initial temperature is 15℃~30℃, maximum working temperature is 100℃, deposition time is 25min~40min, deposition power is 80W~100W; in addition, the inert atmosphere can be set to argon atmosphere, and the argon flux of the magnetron sputtering equipment can be set to 20sccm~50sccm.

[0129] Therefore, by sputtering a lithium-loving metal halide target in an inert atmosphere, lithium-loving metal halides are directly deposited onto the surface of a lithium-loving metal layer, thereby obtaining a metal halide film with stable composition, uniformity, and density. This film can serve as a precursor for subsequent reactions with lithium to form lithium-containing halide interfacial phases. Its low electronic conductivity and good chemical stability contribute to improving interfacial chemical stability.

[0130] In some embodiments, a method for depositing at least one of a lithium-loving metal nitride and a lithium-loving metal halide on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer includes: In the case of depositing lithium-loving metal nitrides and lithium-loving metal halides, a magnetron sputtering apparatus containing a lithium-loving metal current collector is used to co-deposit lithium-loving metal halide targets and lithium-loving metal nitride targets under inert atmosphere conditions to obtain a lithium-loving metal current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 25min~40min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0131] In practical applications, when the lithium-ion metal compound layer includes both lithium-ion metal nitrides and lithium-ion metal halides, the lithium-ion metal compound layer can be obtained by co-sputtering deposition of the lithium-ion metal halide target and the lithium-ion metal nitride target. For example, when depositing lithium-ion metal nitrides and lithium-ion metal halides, the lithium-ion metal halide target and the lithium-ion metal nitride target can be co-deposited under an inert atmosphere using a magnetron sputtering device containing a negative electrode current collector with a lithium-ion metal layer, to obtain a negative electrode current collector containing both a lithium-ion metal layer and a lithium-ion metal compound layer.

[0132] To ensure that the deposited lithium-friendly metal compound layer meets the preset performance requirements in terms of thickness, the base vacuum of the magnetron sputtering equipment can be set to 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa, working gas pressure is 1Pa~5Pa, initial temperature is 15℃~30℃, maximum working temperature is 100℃, deposition time is 25min~40min, deposition power is 80W~100W; in addition, the inert atmosphere can be set to argon atmosphere, and the argon flux of the magnetron sputtering equipment can be set to 20sccm~50sccm.

[0133] Therefore, by simultaneously sputtering lithium-loving metal nitride and lithium-loving metal halide targets, nitride and halide components coexist in the same film layer, forming a mixed lithium-loving metal compound layer with tunable composition and uniform phase distribution. This composite layer can form a multiphase structure containing both lithium-containing nitrides and lithium-containing halides during the formation process, giving the interface high ionic conductivity, good electronic insulation, and chemical stability, which is beneficial for improving the overall interface performance and lithium deposition uniformity.

[0134] In some embodiments, a method for depositing an inorganic lithium-ion conductor on the side of a lithium-philic metal compound layer away from the negative electrode current collector to obtain a negative electrode sheet containing an artificial interface modification layer includes: In an inert atmosphere, an inorganic lithium-ion conductor target is deposited using a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-philic metal layer and a lithium-philic metal compound layer, to obtain a negative electrode sheet with an artificial interface modification layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; optionally, the working gas pressure of the magnetron sputtering equipment is 1Pa~5Pa; optionally, the initial temperature of the magnetron sputtering equipment is 15℃~30℃; optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; optionally, the deposition time of the magnetron sputtering equipment is 10min~20min; optionally, the deposition power of the magnetron sputtering equipment is 80W~100W; optionally, the inert atmosphere is argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20sccm~50sccm.

[0135] In practical applications, after the deposition of the lithium-loving metal layer and the lithium-loving metal compound layer is completed, the deposition of the inorganic lithium-ion conductor layer can be carried out to obtain the negative electrode sheet containing the artificial interface modification layer.

[0136] The deposition of inorganic lithium-ion conductors can be achieved using magnetron sputtering equipment. For example, an inorganic lithium-ion conductor target can be deposited under inert atmosphere conditions by controlling a magnetron sputtering equipment containing a negative electrode current collector with a lithium-philic metal layer and a lithium-philic metal compound layer to obtain a negative electrode sheet with an artificial interface modification layer.

[0137] To ensure that the deposited inorganic lithium-ion conductor layer meets preset requirements in terms of thickness and other performance parameters, the base vacuum level of the magnetron sputtering equipment can be set to 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa, working gas pressure is 1Pa~5Pa, initial temperature is 15℃~30℃, maximum working temperature is 100℃, deposition time is 10min~20min, deposition power is 80W~100W; in addition, the inert atmosphere can be set to argon atmosphere, and the argon flux of the magnetron sputtering equipment can be set to 20sccm~50sccm.

[0138] Therefore, by sputtering an inorganic lithium-ion conductor target, inorganic lithium salt materials are directly deposited on a lithium-philic metal compound layer, forming an electronically insulating and ionicly conductive inorganic lithium-ion conductor layer. This layer can stably provide lithium-ion migration channels for the interface, and at the same time, it acts as an outer protective film to supplement the inorganic components in the interface, improving the mechanical and chemical stability of the interface, thereby enhancing the interface's tolerance to repeated cycling.

[0139] After deposition, a uniformly colored, dense, and firmly bonded artificial interface modification layer is obtained on the surface of the current collector, resulting in a modified negative electrode current collector, i.e., a negative electrode sheet containing the artificial interface modification layer. The thickness of the artificial interface modification layer can be controlled by adjusting the deposition arc current, deposition power, and deposition time; for example, the thickness of the entire artificial interface modification layer can be controlled within the range of 200 nm to 600 nm.

[0140] The deposition process described above does not have strict requirements on experimental temperature. The deposition process can be flexibly adjusted according to the needs of different modified layers to achieve optimal layer performance. The cathode magnetic filtration vacuum arc deposition process and magnetron sputtering equipment can be integrated and are compatible with existing roll-to-roll systems, effectively achieving large-area, low-cost modification of current collectors. This process integration not only improves production efficiency but also reduces production costs, possessing excellent potential for industrial application, and is particularly suitable for the large-scale production needs in the battery industry. Furthermore, the flexibility and adjustability of the process enable it to meet the requirements of different battery technologies, providing strong support for the optimization and improvement of battery manufacturing processes.

[0141] In some embodiments, the method for preparing a single battery cell further includes: The first electrodeless solid-state lithium metal battery cell is subjected to a formation process so that the artificial interface modification layer reacts in situ with the electrochemically deposited lithium metal to obtain the second electrodeless solid-state lithium metal battery cell. In the second negative electrode-free solid lithium metal battery cell, the negative electrode sheet includes a negative electrode current collector and an interface layer located on at least one side of the negative electrode current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative electrode current collector. Wherein, M is a lithium-loving metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

[0142] During the initial charge / discharge formation stage of a first-state, electrodeless solid-state lithium metal battery cell, the following irreversible electrochemical transformation process occurs: Lithium ions are deposited on the negative electrode side to form metallic lithium, which then undergoes an in-situ reduction reaction with the artificial interface modification layer in the first state. This generates an interface layer comprising a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative electrode current collector. This irreversibly transforms the battery cell from the first state to the second state. Taking an artificial interface modification layer composed of a Mg-containing lithium-ion metal layer, a Mg3N2-containing lithium-ion metal compound layer, and a LiF-containing inorganic lithium-ion conductor layer as an example: Mg3N2 +6Li + 6e →2Li3N +3Mg yMg + xLi → Li x Mg y Li3N and Li x Mg y The reaction products are generated in situ in the region where the modified layer is located, forming a Li-M alloy layer near the current collector. Within the Li-M alloy phase of this layer, inorganic components rich in Li3N are embedded. Because Li3N has high lithium-ion conductivity but is almost non-conductive to electrons, while the generated Li-M alloy phase possesses excellent electronic conductivity and provides sufficient lithiophilic sites, it induces uniform and dense lithium metal deposition. Together, they constitute a Li-M alloy-lithium-containing compound layer with high ion transport performance, limited electronic transport performance, and stable lithium deposition. Finally, the LiF in the inorganic lithium-ion conductor layer effectively avoids interfacial side reactions during the initial cycling process and helps increase the inorganic components in the SEI, enhancing its ion transport performance and long-term stability.

[0143] In summary, because lithium halides and / or lithium nitrides in the Li-M alloy-lithium compound layer have high lithium-ion conductivity and almost no electronic conductivity, they can provide continuous lithium-ion migration channels, thereby forming a stable lithium-ion transport network. This effectively reduces the ion transport impedance at the interface, thus effectively avoiding the current density concentration phenomenon caused by ion transport obstruction during lithium metal deposition. This helps to reduce lithium dendrite formation and capacity decay of individual cells, and improves the cycle performance and safety performance of individual cells.

[0144] Furthermore, since the Li-M alloy phase contains a lithium-loving metal, it helps to provide lithium nucleation and growth sites while providing electrons, thereby controlling lithium deposition to occur on the side of the interface layer near the negative electrode current collector. This effectively avoids direct contact between metallic lithium and the electrolyte, thus avoiding the increase in interface impedance and capacity decay caused by side reactions, and improving the cycle performance of the battery cell.

[0145] Furthermore, the inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium compound layer away from the negative electrode current collector can supplement the inorganic components in the SEI during the process of the negative electrode-free solid lithium metal battery cell changing from the first state to the second state. This can effectively improve the mechanical stability of the SEI, reduce the risk of severe lithium dendrite growth during long-term cycling, and further improve the cycle performance of the battery cell.

[0146] Furthermore, the Li-M alloy-lithium compound layer is a composite structure composed of Li-M alloy and lithium compounds including lithium nitride and / or lithium halide. This means that the composite structure can form a continuous transition interface between the Li-M alloy layer and the inorganic lithium-ion conductor layer. This helps to mitigate interface layer stress under volume fluctuations caused by repeated lithium deposition / stripping, reduces the probability of void formation in the interface layer, and enables each layer in the interface layer to maintain a more stable solid-solid bond. This further reduces local current density fluctuations and interface polarization, improving the cycle performance and safety performance of the battery cell.

[0147] It should be noted that, in the embodiments of this application, the first electrodeless solid-state lithium metal battery cell is the electrodeless solid-state lithium metal battery cell in the first state, and the second electrodeless solid-state lithium metal battery cell is the electrodeless solid-state lithium metal battery cell in the second state.

[0148] In embodiments of this application, the positive electrode includes a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector and including a positive electrode active material.

[0149] It is understood that the positive electrode active material layer can be disposed on one surface of the positive electrode current collector or on both surfaces of the positive electrode current collector. This application does not impose any particular limitation on this.

[0150] The positive current collector can be a metal foil or a porous metal plate, such as foil or porous plate of metals or alloys thereof, such as aluminum, copper, nickel, titanium, iron, etc. In some embodiments of this application, the positive current collector is aluminum foil.

[0151] In some embodiments of this application, the positive electrode active material may be selected from at least one of the following: lithium manganese iron phosphate, lithium iron phosphate, lithium manganese phosphate, etc., olivine structure materials, NCM811, NCM622, NCM523, NCM333, etc., lithium cobalt oxide materials, lithium manganese oxide materials, and other metal oxides capable of lithium intercalation / deintercalation.

[0152] In some embodiments of this application, the positive electrode active material layer further includes a conductive agent selected from at least one of carbon-based materials, metal-based materials, conductive polymers, and mixtures thereof. Exemplarily, the carbon-based material is selected from carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanotubes, or any combination thereof. The metal-based material is selected from metal powder, metal fibers, copper, nickel, aluminum, or silver. The conductive polymer is a polyphenylene derivative.

[0153] In some embodiments of this application, the positive electrode sheet can be prepared by conventional dry processes suitable for solid-state batteries. For example, the positive electrode active material, solid electrolyte and conductive agent are dry-mixed to form a uniform composite positive electrode material; then the material is placed in a mold and pressed under a certain pressure to form a dense positive electrode sheet with good solid-solid contact.

[0154] Thirdly, embodiments of this application provide a battery device comprising a negative electrode-free solid lithium metal battery cell as described in the first aspect, or a negative electrode-free solid lithium metal battery cell prepared by the method described in the second aspect.

[0155] Fourthly, embodiments of this application provide an electrical device comprising a negative electrode-free solid lithium metal battery cell (as described in the first aspect), a negative electrode-free solid lithium metal battery cell (as described in the second aspect), or a battery device (as described in the third aspect).

[0156] In some embodiments, the electrical devices provided in this application are applicable to various electrical devices that use solid-state battery cells and battery devices, such as including but not limited to mobile devices (e.g., mobile phones, tablets, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc. Solid-state battery cells and battery devices are used to store or provide electrical energy.

[0157] Example The following embodiments describe the disclosure of this application in more detail. These embodiments are merely illustrative, as various modifications and variations will be apparent to those skilled in the art within the scope of the disclosure of this application. Unless otherwise stated, all parts, percentages, and ratios reported in the following embodiments are based on weight, and all reagents used in the embodiments are commercially available or synthesized by conventional methods and can be used directly without further processing, and the instruments used in the embodiments are commercially available.

[0158] In the various embodiments and comparative examples of this application, battery cells are prepared using the following methods, and the performance of the battery cells is tested.

[0159] Example 1 Preparation method of battery cell Preparation of negative electrode sheets containing artificial interface modification layers 1. Materials and Environment Metal current collector: Commercial high-purity rolled copper foil, 9μm thick; Target materials: Zhongnuo New Materials purchased high-purity magnesium metal target material with a size of 100 mm × 20 mm and a purity of 99.99%, and high-purity magnetron sputtering lithium fluoride target material with a size of 76.2 mm × 5 mm and a purity of 99.99%. Cleaning solvent: analytical grade anhydrous ethanol; Environmental protection: An argon-filled glove box with a water and oxygen content of <0.1ppm is used for storage; Reaction equipment: BNU100 multi-functional integrated deposition equipment, including FCVAD cathode magnetic filter vacuum arc deposition equipment, radio frequency magnetron sputtering equipment, and Mevva source / Koffman ion source ion etching equipment.

[0160] 2. Preprocessing A 9 μm thick copper foil substrate was placed in anhydrous ethanol and ultrasonically cleaned for 15 min at room temperature to remove surface oil, adsorbed water, and easily detachable oxides. After cleaning, the copper foil was removed and dried in a vacuum drying oven at room temperature for 30 min. It was then cut into 20 cm × 20 cm pieces and fixedly placed in the deposition chamber.

[0161] 3. Preparation of artificial interface modification layers using multi-step PVD technology like Figure 1 The diagram shown is a schematic of the process for preparing an artificial interface modification layer using a BNU100 multi-functional deposition apparatus via physical vapor deposition in Embodiment 1 of this application. The process may specifically include the following steps: 1) Adjust the background vacuum to 3.0×10 -3 Below Pa, argon gas is introduced into the device using a Kaufman ion source system to generate argon ions. The copper current collector is then etched and cleaned by a magnetic filtration system to remove oxides and other contaminants from its surface and to perform initial activation treatment.

[0162] 2) The processed current collector is transported via a transmission system to the FCVAD cathode magnetic filter vacuum arc deposition module chamber for lithium-philic magnesium metal layer deposition. The deposition process meets the following conditions: background vacuum degree ≤ 3.0 × 10⁻⁶ -3 Pa, working gas pressure is 0.05 Pa, arc current is 100 A, initial cavity temperature is 15℃~30℃ and does not exceed 150℃ during deposition; start deposition of lithium-loving metal Mg buffer layer, deposition time is 10 min.

[0163] 3) Turn off the arc power supply when the background vacuum is ≤3.0×10 -3 At Pa, nitrogen gas is introduced at a flow rate of 30 sccm to 80 sccm to achieve the formation of a lithium-loving metal compound layer, namely the Mg3N2 layer, thus obtaining a negative electrode current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer.

[0164] The current collector, with the deposited lithium-ion metal layer and lithium-ion compound layer, is then transferred to the magnetron sputtering deposition system chamber via a transmission system for the deposition of an inorganic lithium-ion conductor layer, with the background vacuum level adjusted to ≤5.0×10⁻⁶. -3 Pa, argon flow rate adjusted to 20 sccm, working pressure adjusted to 1 Pa~5 Pa, initial cavity temperature adjusted to 15℃~30℃ and set to not exceed 100℃ during deposition; among which, the deposition power of the LiF inorganic lithium-ion conductor layer is 80W, and the deposition time of the lithium-loving metal compound layer is 30min.

[0165] 4. Post-processing The deposited sample was allowed to cool statically in an Ar atmosphere. The sample was then transferred to an argon glove box and cut into 15mm diameter sheets to obtain a negative electrode sheet containing an artificial interface modification layer, denoted as Mg-Mg3N2-LiF@Cu.

[0166] 5. Morphology and thickness confirmation Figure 2 The SEM images and elemental distribution maps of the cross-section of the negative electrode sheet prepared in Example 1 are shown. Figure 2 The results show that the prepared artificial interface modification layer is continuous and dense, with a uniformly distributed layered structure and a layer thickness of approximately 450 nm. EDS signals indicate that the Mg layer thickness is approximately 250 nm, the Mg3N2 layer thickness is approximately 150 nm, and the LiF layer thickness is approximately 50 nm. Figure 3 The XPS signals of the Mg3N2 and LiF layers after deposition are shown respectively, demonstrating the accurate preparation of the Mg3N2 and LiF layers.

[0167] Assembly of coin cell Li-Cu half-cell The electrolyte system shown in Table 1 is used: Table 1

[0168] A total of 60 μL of lithium salt and electrolyte solvent, and a total of 6 μL of initiator and initiator solvent were added to the CR2032 coin cell casing. A negative electrode sheet containing an artificial interface modification layer, namely Mg-Mg3N2-LiF@Cu, was used as the working electrode, and a Li sheet was used as the counter electrode. The DOL ring-opening polymerization was completed by standing at room temperature for 24 h to obtain Li|Mg-Mg3N2-LiF@Cu half cell.

[0169] Assembly of button-type LFP positive electrode configuration full cell The electrolyte system shown in Table 2 is used: Table 2

[0170] A total of 60 μL of lithium salt and electrolyte solvent, and a total of 6 μL of initiator and initiator solvent were added to the CR2032 coin cell casing. A negative electrode containing an artificial interface modification layer, namely Mg-Mg3N2-LiF@Cu, was used as the negative electrode. (4 mg*cm) -2 Using an electrode with high LFP active material content as the positive electrode, DOL ring-opening polymerization was completed by standing at room temperature for 24 hours to obtain an LFP|Mg-Mg3N2-LiF@Cu full cell.

[0171] Performance testing Half-cell cycle performance testing: The Li|Mg-Mg3N2-LiF@Cu half-cell was tested for cycle performance under the following electrochemical conditions: Test temperature: room temperature, approximately 25℃; Cyclic current density: 0.2 mA*cm² -2 Single deposition / stripping capacity: 0.2 mAh*cm³ -2 Subsequently, the parallel sample current density was increased to 0.5 mA*cm. -2 Single deposition / stripping capacity: 0.5 mAh*cm -2 Voltage range: 0V~1.0V, with reference to the working electrode.

[0172] Full cell cycle performance test: The LFP|Mg-Mg3N2-LiF@Cu full cell was tested for cycle performance under the following electrochemical test conditions: test temperature: room temperature, about 25℃; cycle rate 0.1C, activation rate 0.05C, cell activation 3 cycles; voltage window: 2.5V~4.0V.

[0173] Test Results Half-cell test results: like Figure 4 The figure shows the effect at a circulating current density of 0.2 mA*cm. -2 Single deposition / stripping capacity: 0.2 mAh*cm³ -2 The schematic diagrams of the cycling performance of Li|Mg-Mg3N2-LiF@Cu half-cell and Li|Cu coin cell under the specified conditions show that, compared with the Li|Cu half-cell that only uses copper foil as the negative electrode current collector, the Li|Mg-Mg3N2-LiF@Cu half-cell can cycle stably for over 400 hours (more than 200 cycles) with a higher coulombic efficiency, an average coulombic efficiency of 98.12%, and less voltage polarization without abrupt changes; while... Figure 5 The figure shows the effect at a circulating current density of 0.5 mA*cm. -2 Single deposition / stripping capacity: 0.5 mAh*cm -2The following diagrams illustrate the cycling performance of the Li|Mg-Mg3N2-LiF@Cu half-cell and the Li|Cu half-cell. It can be seen that when the current density increases to 0.5 mA*cm², the cycling performance becomes significantly higher. -2 Single deposition / stripping capacity: 0.5 mAh*cm -2 At that time, the Li|Mg-Mg3N2-LiF@Cu half-cell could still cycle stably for 400 hours, which is more than 200 cycles, and the average coulombic efficiency was 94.91%.

[0174] Full battery test results: like Figure 6 The diagram shows the cycling performance of LFP|Mg-Mg3N2-LiF@Cu coin cells and LFP|Cu coin cells with LFP cathode configuration under a cycling rate of 0.1C. It can be seen that under a cycling rate of 0.1C, the LFP|Mg-Mg3N2-LiF@Cu coin cell can be stably cycled for more than 160 times, with an average coulombic efficiency of 99.54% and a capacity retention of more than 60%.

[0175] Comparative Example 1 The only difference between Comparative Example 1 and Example 1 is that the Mg-Mg3N2-LiF@Cu negative electrode sheet in Example 1 was replaced with a commercially available high-purity rolled copper foil with a thickness of 9 μm, thereby preparing the corresponding Li|Cu coin half cell and LFP|Cu coin full cell.

[0176] Performance testing Half-cell cycle performance testing: The Li|Cu half-cell was cycled under the following electrochemical test conditions: Test temperature: room temperature, approximately 25°C; Cyclic current density: 0.2 mA*cm² -2 Single deposition / stripping capacity: 0.2 mAh*cm³ -2 Subsequently, the parallel sample current density was increased to 0.5 mA*cm. -2 Single deposition / stripping capacity: 0.5 mAh*cm -2 Voltage range: 0V~1.0V, with reference to the working electrode.

[0177] Full cell cycle performance test: The LFP|Cu full cell was cycled under the following electrochemical test conditions: test temperature: room temperature, about 25 ℃; cycle rate 0.1C, activation rate 0.05C, cell activation 3 cycles; voltage window: 2.5V~4.0V.

[0178] Test Results Half-cell results: like Figure 4 As shown, at a circulating current density of 0.2 mA*cm -2Single deposition / stripping capacity: 0.2 mAh*cm³ -2 Under these conditions, the Li|Cu half-cell can cycle stably for 150 hours, or about 75 cycles, after which the coulombic efficiency fluctuates significantly, with an average coulombic efficiency of only 87.34%; while... Figure 5 As shown, when the current density increases to 0.5 mA*cm -2 Single deposition / stripping capacity: 0.5 mAh*cm -2 At that time, the Li|Cu half-cell could only cycle stably for 150 hours, or about 75 cycles. After that, the coulombic efficiency dropped significantly, with an average coulombic efficiency of only 85.18% throughout the entire cycle.

[0179] Full cell results: like Figure 6 As shown, under a cycle rate of 0.1C, the LFP|Cu coin cell can only be stably cycled about 20 times, after which its capacity rapidly decays.

[0180] Example 2 Preparation method of battery cell Preparation of negative electrode sheets containing artificial interface modification layers 1. Materials and Environment Metal current collector: Commercial high-purity rolled copper foil, 9μm thick; Target materials: Zhongnuo New Materials purchased high-purity magnesium metal target material with a size of 100 mm × 20 mm and a purity of 99.99%, and high-purity magnetron sputtering lithium fluoride target material with a size of 76.2 mm × 5 mm and a purity of 99.99%. Cleaning solvent: analytical grade anhydrous ethanol; Environmental protection: An argon-filled glove box with a water and oxygen content of <0.1ppm is used for storage; Reaction equipment: BNU100 multi-functional integrated deposition equipment, including FCVAD cathode magnetic filter vacuum arc deposition equipment, radio frequency magnetron sputtering equipment, and Mevva source / Koffman ion source ion etching equipment.

[0181] 2. Preprocessing A 9 μm thick copper foil substrate was placed in anhydrous ethanol and ultrasonically cleaned for 15 min at room temperature to remove surface oil, adsorbed water, and easily detachable oxides. After cleaning, the copper foil was removed and dried in a vacuum drying oven at room temperature for 30 min. It was then cut into 20 cm × 20 cm pieces and fixedly placed in the deposition chamber.

[0182] 3. Preparation of artificial interface modification layers using multi-step PVD technology The processing steps are the same as those in Example 1, except that an artificial interface modification layer is provided on both sides of the current collector.

[0183] 4. Post-processing The deposited sample was allowed to cool statically in an Ar atmosphere. The sample was then transferred to an argon glove box and subsequently cut into 4cm × 7cm flexible electrode sheets in a drying chamber, yielding a negative electrode sheet containing an artificial interface modification layer, denoted as Mg-Mg3N2-LiF@Cu.

[0184] Assembly of all cells with pouch-type LFP cathode configuration The electrolyte system shown in Table 3 is used: Table 3

[0185] Mg-Mg3N2-LiF@Cu was used as the negative electrode in an alternating stacking manner, 25mg*cm -2 LFP active material-rich electrodes are stacked as positive electrodes, with each pouch cell containing a total of 2 LFP positive electrodes and 3 negative electrodes. Finally, 2g*Ah is injected into the pouch cell. -1 The electrolyte and corresponding initiator were prepared, with a volume ratio of electrolyte to initiator of 10:1. The electrolyte included lithium salts and electrolyte solvents as listed in Table 3, and the initiator included in-situ polymerization initiators and initiator solvents as listed in Table 3. Finally, the DOL ring-opening polymerization was completed by standing at room temperature for 24 h to obtain LFP|Mg-Mg3N2-LiF@Cu soft-pack full cells.

[0186] Performance testing Full cell cycle performance test: The cycle performance of LFP|Mg-Mg3N2-LiF@Cu soft-pack full cells was tested under the following electrochemical test conditions: Test temperature: room temperature, about 25 ℃; cycle rate 0.1C, activation rate 0.05C, long cycle after 3 activation cycles; voltage window: 2.5V~3.7V.

[0187] Test Results like Figure 7 The diagram shows the cycling performance of LFP|Mg-Mg3N2-LiF@Cu pouch cells and LFP|Cu pouch cells with LFP cathode configuration under a cycling rate of 0.1C. It can be seen that under a cycling rate of 0.1C, the LFP|Mg-Mg3N2-LiF@Cu pouch cell can be stably cycled for more than 50 times, with an average coulombic efficiency of 99.23% and a capacity retention of more than 50%.

[0188] Comparative Example 2 The only difference between Comparative Example 2 and Example 2 is that the Mg-Mg3N2-LiF@Cu negative electrode sheet in Example 2 was replaced with a commercially available high-purity rolled copper foil with a thickness of 9 μm, thereby preparing the corresponding LFP|Cu soft-pack full cell.

[0189] Test Results like Figure 7 As shown, under a cycle rate of 0.1C, the LFP|Cu pouch cell has a low coulombic efficiency and its capacity decays rapidly throughout the cycle.

[0190] Example 3 Preparation method of battery cell Preparation of negative electrode sheets containing artificial interface modification layers The preparation method is the same as in Example 2.

[0191] Assembly of pouch-type NCM811 cathode configuration full cell The electrolyte system shown in Table 4 is used: Table 4

[0192] Mg-Mg3N2-LiF@Cu was used as the negative electrode in an alternating stacking manner, 25mg*cm -2 Electrodes with high NCM811 active material content are stacked as positive electrodes. Each pouch cell contains a total of 2 NCM811 positive electrodes and 3 negative electrodes, ultimately arranged in a 2g*Ah configuration within the pouch cell. -1 An appropriate amount of electrolyte containing initiator and crosslinking agent was injected. The mixture was then placed in a 70°C oven for 24 hours to complete the electrolyte crosslinking polymerization, yielding an NCM811|Mg-Mg3N2-LiF@Cu full cell.

[0193] Performance testing Full cell cycle performance test: The NCM811|Mg-Mg3N2-LiF@Cu full cell was tested for cycle performance under the following electrochemical test conditions: Test temperature: room temperature, about 25 ℃; cycle rate 0.1C, activation rate 0.05C, long cycle after 3 activation cycles; voltage window: 3.0V~4.3V.

[0194] Test Results like Figure 8The diagram shows the cycling performance of the NCM811|Mg-Mg3N2-LiF@Cu full cell and the NCM811|Cu full cell with NCM811 cathode configuration under a cycling rate of 0.1C. It can be seen that under a cycling rate of 0.1C, the NCM811|Mg-Mg3N2-LiF@Cu pouch cell can be stably cycled for more than 100 times, with an average coulombic efficiency of 99.23% and a capacity retention of more than 50%.

[0195] Comparative Example 3 The only difference between Comparative Example 3 and Example 3 is that the Mg-Mg3N2-LiF@Cu negative electrode sheet in Example 3 was replaced with a commercially available high-purity rolled copper foil with a thickness of 9 μm, thereby preparing the corresponding soft-pack NCM811|Cu full cell.

[0196] Test Results like Figure 8 As shown, under a cycle rate of 0.1C, the NCM811|Cu full cell is very unstable during cycling. After three activation cycles, the coulombic efficiency directly shows a significant decline, and the cell fails.

[0197] As can be seen from the above embodiments and comparative examples, if the interface layer provided in this application is not constructed on the surface of the negative electrode current collector, the deposited lithium will tend to grow disorderly on the electrolyte side and penetrate the electrolyte, resulting in premature failure of the negative electrode-free lithium metal battery. The interface layer provided in this application can significantly extend the cycle life of the negative electrode-free lithium metal battery and improve the first-cycle capacity and cycle stability of the negative electrode-free lithium metal battery.

[0198] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A single-cell, electrodeless solid-state lithium metal battery with multiple interface films, characterized in that, It includes a positive electrode, a negative electrode, and a solid electrolyte layer, wherein the solid electrolyte layer is located between the positive electrode and the negative electrode; The electrodeless solid-state lithium metal battery cell includes a first state and a second state; In the first state, the negative electrode includes a negative current collector and an artificial interface modification layer located on at least one side of the negative current collector. The artificial interface modification layer includes a lithium-philic metal layer, a lithium-philic metal compound layer located on the side of the lithium-philic metal layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-philic metal compound layer away from the negative current collector. The lithium-philic metal compound includes at least one of lithium-philic metal nitride and lithium-philic metal halide. In the second state, the negative electrode includes the negative current collector and an interface layer located on at least one side of the negative current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative current collector. Wherein, M is a lithium-philic metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

2. The electrodeless solid-state lithium metal battery cell according to claim 1, characterized in that, The artificial interface modification layer satisfies one or more of the following conditions: (1) The thickness of the lithium-loving metal layer is 200 nm to 300 nm; (2) The thickness of the lithium-loving metal compound layer is 100 nm to 200 nm; (3) The thickness of the inorganic lithium-ion conductor layer is 50 nm to 150 nm; (4) The lithium-loving metal includes one or more of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium, and bismuth; (5) The lithium-loving metal nitrides include one or more of magnesium nitride, zinc nitride, tin nitride, aluminum nitride, gallium nitride, germanium nitride, indium nitride, and bismuth nitride; (6) The lithium-loving metal halide includes one or more halides of magnesium, zinc, silver, gold, tin, aluminum, gallium, germanium, indium and bismuth; (7) The inorganic lithium-ion conductors include LiF, Li3N, and Li x PO y N z One or more of the following, wherein 2.0≤x≤3.0, 3.0≤y≤4.0, and 0.1≤z≤1.

5.

3. The electrodeless solid-state lithium metal battery cell according to claim 1, characterized in that, The interface layer satisfies one or more of the following conditions: (1) The thickness of the interface layer is 200nm to 500nm; (2) The Young's modulus of the interface layer is 30 GPa to 40 GPa; (3) The activation energy for lithium ion migration in the interface layer is 10 kJ / mol. -1 ~30kJmol -1 ; (4) The mass fraction of lithium compound in the interface layer is 21% to 34%; (5) The mass fraction of the inorganic lithium-ion conductor in the interface layer is 12% to 20%; (6) The mass fraction of Li-M alloy in the interface layer is 46% to 67%.

4. The electrodeless solid-state lithium metal battery cell according to claim 1, characterized in that, The solid electrolyte includes one or more of sulfide solid electrolytes, halide solid electrolytes, oxide solid electrolytes, and polymer-based solid electrolytes, preferably, the solid electrolyte includes polymer-based solid electrolytes.

5. The electrodeless solid-state lithium metal battery cell according to claim 4, characterized in that, The solid electrolyte satisfies one or more of the following conditions: (1) The sulfide solid electrolyte includes Li 10 GeP2S 12 The electrolyte is one or more of the following: a solid electrolyte and a sulfide argyrodite electrolyte Li6PS5X, wherein X is any one of Cl, Br and I, and preferably, the sulfide solid electrolyte is Li6PS5Cl. (2) The halide solid electrolyte includes one or more of ternary halide Li-MX type electrolyte and halide lithium ore type electrolyte Li3EX6, wherein E is any one of Y, Sc, In, Er, Zr, and X is any one of Cl, Br, and I; (3) The oxide solid electrolyte includes NASICON-type electrolyte Li 1+t A t Ge 2-t (PO4)3 and Garnet-type electrolyte Li7La3Zr2O 12 One or more of the following, wherein 0 ≤ t ≤ 0.8, and A is any one of Al and Ga; (4) The polymer-based solid electrolyte includes one or more of the following: a polymer electrolyte system based on polyethylene oxide, a polymer electrolyte system based on polycarbonate, a polymer electrolyte system based on polyvinylidene fluoride-hexafluoropropylene copolymer, and a polymer electrolyte system based on polyacrylonitrile.

6. A method for preparing a single negative electrode-free solid lithium metal battery cell with multiple interface films, characterized in that, include: Provide negative electrode current collector; A lithium-loving metal is deposited on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer; At least one of a lithium-loving metal nitride and a lithium-loving metal halide is deposited on the side of the lithium-loving metal layer away from the negative electrode current collector to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. An inorganic lithium-ion conductor is deposited on the side of the lithium-loving metal compound layer away from the negative electrode current collector to obtain a negative electrode sheet containing an artificial interface modification layer. The artificial interface modification layer includes the lithium-loving metal layer, the lithium-loving metal compound layer located on the side of the lithium-loving metal layer away from the negative electrode current collector, and an inorganic lithium-ion conductor layer located on the side of the lithium-loving metal compound layer away from the negative electrode current collector. The positive electrode, the solid electrolyte layer, and the negative electrode containing the artificial interface modification layer are assembled to obtain the first negative electrode-free solid lithium metal battery cell.

7. The preparation method according to claim 6, characterized in that, Also includes: The first electrodeless solid lithium metal battery cell is subjected to a formation process so that the artificial interface modification layer reacts in situ with the electrochemically deposited lithium metal to obtain the second electrodeless solid lithium metal battery cell. In the second electrodeless solid-state lithium metal battery cell, the negative electrode includes the negative current collector and an interface layer located on at least one side of the negative current collector. The interface layer includes a Li-M alloy layer, a Li-M alloy-lithium-containing compound layer located on the side of the Li-M alloy layer away from the negative current collector, and an inorganic lithium-ion conductor layer located on the side of the Li-M alloy-lithium-containing compound layer away from the negative current collector. Wherein, M is a lithium-loving metal, and the lithium-containing compound includes at least one of lithium nitride and lithium halide.

8. The method according to claim 6 or 7, characterized in that, A method for obtaining a negative electrode current collector containing a lithium-ion metal layer and a lithium-ion metal compound layer by depositing at least one of a lithium-ion metal nitride and a lithium-ion metal halide on the side of the lithium-ion metal layer away from the negative electrode current collector includes at least one of the following methods: Method 1: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into a cathode magnetic filter vacuum arc deposition device containing the negative electrode current collector containing the lithium-loving metal layer to deposit a negative electrode current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the cathode magnetic filtering vacuum arc deposition equipment is a lithium-philic metal target; optionally, the background vacuum degree of the cathode magnetic filtering vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 -3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 °C to 30 °C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 °C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 3 min to 10 min; Optionally, the nitrogen flux of the cathode magnetic filter vacuum arc deposition equipment is 30 sccm to 80 sccm; Method 2: In the case of depositing only lithium-loving metal nitrides, nitrogen gas is introduced into the magnetron sputtering equipment containing the lithium-loving metal layer, or nitrogen gas and inert gas are introduced into the magnetron sputtering equipment containing the lithium-loving metal layer to deposit a negative electrode current collector containing both a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the target material used in the magnetron sputtering equipment is a lithium-philic metal target; optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the operating gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the inert gas is argon, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum operating temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 15 min to 25 min; Optionally, the nitrogen flux of the magnetron sputtering equipment is 40 sccm to 80 sccm; Optionally, the deposition power of the magnetron sputtering equipment is 80 W to 100 W; Method 3: In the case of depositing only lithium-loving metal nitride, a magnetron sputtering device containing the lithium-loving metal layer is controlled to deposit a lithium-loving metal nitride target under inert atmosphere conditions to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the working gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 15 min to 25 min; Optionally, the deposition power of the magnetron sputtering equipment is 80 W to 100 W; Optionally, the inert atmosphere is an argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm; Method 4: In the case of depositing only lithium-loving metal halides, a magnetron sputtering device containing the lithium-loving metal layer is controlled to deposit a lithium-loving metal halide target under inert atmosphere conditions to obtain a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the working gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 25 min to 40 min; Optionally, the deposition power of the magnetron sputtering equipment is 80 W to 100 W; Optionally, the inert atmosphere is an argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm; Method 5: In the case of depositing lithium-loving metal nitrides and lithium-loving metal halides, a magnetron sputtering device containing a negative electrode current collector with a lithium-loving metal layer is controlled under inert atmosphere to co-deposit lithium-loving metal halide targets and lithium-loving metal nitride targets, thereby obtaining a negative electrode current collector containing a lithium-loving metal layer and a lithium-loving metal compound layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the working gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 25 min to 40 min; Optionally, the deposition power of the magnetron sputtering equipment is 80 W to 100 W; Optionally, the inert atmosphere is an argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm.

9. The method according to claim 6 or 7, characterized in that, A method for depositing a lithium-philic metal on at least one side of the negative electrode current collector to obtain a negative electrode current collector containing a lithium-philic metal layer includes at least one of the following methods: Method 1: Deposit a lithium-loving metal target using a magnetron sputtering device containing the negative electrode current collector under inert atmosphere conditions to obtain the negative electrode current collector containing the lithium-loving metal layer; Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the working gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 20 min to 60 min; Optionally, the deposition power of the magnetron sputtering equipment is 100 W to 150 W; Optionally, the inert atmosphere is an argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm; Method 2: Deposit a lithium-loving metal target using a cathode magnetic filter vacuum arc deposition device containing the negative electrode current collector to obtain the negative electrode current collector containing the lithium-loving metal layer; Optionally, the background vacuum level of the cathode magnetic filter vacuum arc deposition equipment is 9.0 × 10⁻⁶. -4 Pa ~ 3.0 × 10 -3 Pa; Optionally, the working gas pressure of the cathode magnetic filter vacuum arc deposition equipment is 0.01 Pa to 0.1 Pa; Optionally, the arc current of the cathode magnetic filter vacuum arc deposition equipment is 80 A to 120 A; Optionally, the initial temperature of the cathode magnetic filter vacuum arc deposition equipment is 15 ° C to 30 ° C; Optionally, the maximum working temperature of the cathode magnetic filter vacuum arc deposition equipment is 150 ° C; Optionally, the deposition time of the cathode magnetic filter vacuum arc deposition equipment is 5 min to 15 min.

10. The method according to claim 6 or 7, characterized in that, A method for obtaining a negative electrode sheet containing an artificial interface modification layer by depositing an inorganic lithium-ion conductor on the side of the lithium-philic metal compound layer away from the negative electrode current collector includes: An inorganic lithium-ion conductor target is deposited under inert atmosphere conditions using a magnetron sputtering apparatus containing a negative electrode current collector with a lithium-philic metal layer and a lithium-philic metal compound layer, to obtain a negative electrode sheet with an artificial interface modification layer. Optionally, the background vacuum of the magnetron sputtering equipment is 9.0 × 10⁻⁶. -4 Pa ~ 5.0 × 10 -3 Pa; Optionally, the working gas pressure of the magnetron sputtering equipment is 1 Pa to 5 Pa; Optionally, the initial temperature of the magnetron sputtering equipment is 15℃ to 30℃; Optionally, the maximum working temperature of the magnetron sputtering equipment is 100℃; Optionally, the deposition time of the magnetron sputtering equipment is 10 min to 20 min; Optionally, the deposition power of the magnetron sputtering equipment is 80 W to 100 W; Optionally, the inert atmosphere is an argon atmosphere, and the argon flux of the magnetron sputtering equipment is 20 sccm to 50 sccm.

11. A battery device, characterized in that, The battery device comprises a negative electrode-free solid lithium metal battery cell as described in any one of claims 1-5, or a negative electrode-free solid lithium metal battery cell prepared by the method described in any one of claims 6-10.

12. An electrical appliance, characterized in that, The electrical device includes a negative electrode-free solid lithium metal battery cell as described in any one of claims 1-5, or a negative electrode-free solid lithium metal battery cell prepared by the method described in any one of claims 6-10, or the battery device as described in claim 11.

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