Method for preparing anode structure and battery comprising anode structure

Abstract

Some embodiments in the present disclosure provide methods of making an anode structure and batteries including the anode structure. The method for preparing the anode structure comprises the following steps of: performing normal-pressure atmospheric plasma treatment on the copper-containing conductive layer to form a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure; and connecting the transitional anode structure with the negative electrode, connecting the lithium-containing electrode with the positive electrode, and charging the half-cell system, so that the copper nitride in the copper nitride film is converted into lithium nitride, thereby obtaining the anode structure. The lithium nitride film is formed on the copper-containing conductive layer by processing the copper-containing conductive layer in cooperation with normal-pressure atmospheric plasma and carrying out charging reaction on the processed copper-containing conductive layer, so that the discharge capacitance of the battery can be improved, the generation of impurities during charging and discharging is reduced, and the service life is prolonged.

Description

Technical Field

[0001] Some embodiments of the present disclosure include methods for preparing an anode structure and batteries comprising the anode structure. Background Art

[0002] Lithium-ion batteries (LIB) are widely used due to their advantages such as high energy density, high output voltage, and low self-discharge rate.

[0003] To further increase energy density and reduce battery size, anode-free lithium metal batteries (AFLMBs) have emerged. The key principle of AFLMBs lies in lithium transfer: the anode structure does not contain the active component, lithium metal, but rather the cathode structure. During the charging reaction, lithium metal is deposited on the anode structure to serve as the anode active component. However, the deposition of a conductive layer (e.g., copper foil) in the anode structure and the efficiency of the reversible reaction for lithium desorption are limited, limiting the battery's electrochemical performance.

[0004] Therefore, how to provide an anode structure that can enhance lithium reaction efficiency and improve electrochemical performance is a problem to be solved. Summary of the Invention

[0005] Some embodiments of the present disclosure provide a method for preparing an anode structure, comprising: providing a copper-containing conductive layer; performing atmospheric plasma treatment on the copper-containing conductive layer using a reaction gas comprising a nitrogen-containing gas to form a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure; providing a lithium-containing electrode and a half-cell electrolyte; using the transitional anode structure as a working electrode and the lithium-containing electrode as an auxiliary electrode, and assembling the working electrode, the auxiliary electrode, and the half-cell electrolyte into a half-cell system; and connecting the transitional anode structure to a negative electrode and the lithium-containing electrode to a positive electrode, and charging the half-cell system to convert the copper nitride in the copper nitride film into lithium nitride, thereby obtaining an anode structure, wherein the anode structure comprises a copper-containing conductive layer and a lithium nitride film covering the copper-containing conductive layer.

[0006] In some embodiments, the copper-containing conductive layer comprises copper foil, copper mesh, copper foam, or a combination thereof.

[0007] In some embodiments, before subjecting the copper-containing conductive layer to the atmospheric plasma treatment, the method includes cleaning the copper-containing conductive layer with an acidic solution.

[0008] In some embodiments, the acidic solution comprises hydrochloric acid, acetic acid, nitric acid, or a combination thereof.

[0009] In some embodiments, the concentration of the acidic solution is 0.005 mol / L to 2 mol / L.

[0010] In some embodiments, the nitrogen-containing gas comprises nitrogen, ammonia, or a combination thereof.

[0011] In some embodiments, the reaction gas further comprises another inert gas.

[0012] In some embodiments, the volume ratio of the nitrogen-containing gas to the other inert gas is 1:5 to 5:1.

[0013] In some embodiments, the step of performing atmospheric plasma treatment on the copper-containing conductive layer comprises moving a gas showerhead in an S-shaped manner to perform atmospheric plasma treatment on the copper-containing conductive layer.

[0014] In some embodiments, the lithium-containing electrode comprises a lithium metal sheet, a lithium-containing compound, or a combination thereof.

[0015] In some embodiments, the half-cell electrolyte comprises lithium ions.

[0016] In some embodiments, the step of charging the half-cell system comprises charging the half-cell system using a current of 0.1 mA / cm2 to 0.5 mA / cm2 until the voltage reaches 0 volts.

[0017] Some embodiments of the present disclosure provide a battery comprising: an anode structure prepared by the aforementioned method, a cathode structure, and an electrolyte. The cathode structure comprises lithium metal. The electrolyte is electrically connected to the anode structure and the cathode structure.

[0018] In some embodiments, the cathode structure further comprises nickel, cobalt, manganese, iron, and aluminum.

[0019] In some embodiments, the electrolyte comprises lithium ions.

[0020] Some embodiments of the present disclosure provide a method for preparing an anode structure, comprising: providing a copper-containing conductive layer; cleaning the copper-containing conductive layer with an acidic solution; forming a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure; providing a lithium-containing electrode and a half-cell electrolyte; using the transitional anode structure as a working electrode and the lithium-containing electrode as an auxiliary electrode, and assembling the working electrode, the auxiliary electrode, and the half-cell electrolyte into a half-cell system; and connecting the transitional anode structure to a negative electrode and the lithium-containing electrode to a positive electrode, and charging the half-cell system to convert copper nitride in the copper nitride film into lithium nitride, thereby obtaining an anode structure, wherein the anode structure comprises a copper-containing conductive layer and a lithium nitride film covering the copper-containing conductive layer.

[0021] In some embodiments, the acidic solution comprises hydrochloric acid, acetic acid, nitric acid, or a combination thereof.

[0022] In some embodiments, the step of forming a copper nitride film on the copper-containing conductive layer includes performing an atmospheric plasma treatment on the copper-containing conductive layer using a reaction gas including a nitrogen-containing gas.

[0023] In some embodiments, the step of charging the half-cell system comprises charging the half-cell system using a current of 0.1 mA / cm2 to 0.5 mA / cm2 until the voltage reaches 0 volts.

[0024] Some embodiments of the present disclosure provide a battery comprising: an anode structure prepared by the aforementioned method, a cathode structure, and an electrolyte. The cathode structure comprises lithium metal. The electrolyte is electrically connected to the anode structure and the cathode structure.

[0025] It is to be understood that both the foregoing general description and the following detailed description are examples, and are intended to provide further explanation of the disclosure as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] To make the above and other objects, features, advantages and embodiments of the present invention more apparent, the detailed description of the accompanying drawings is as follows:

[0027] Figure 1 A flow chart of a method for preparing an anode structure according to some embodiments of the present application;

[0028] Figure 2 In some embodiments of the present application, the moving path of the gas nozzle when treating the copper-containing conductive layer using atmospheric plasma at normal pressure is illustrated;

[0029] Figure 3 A flow chart of a method for preparing an anode structure according to other embodiments of the present application;

[0030] Figure 4 In an embodiment of the present disclosure, after cleaning the copper-containing conductive layer with different acidic solutions, charge-discharge cycle tests were performed on each set of half-cells. The relationship between the capacitance and coulombic efficiency of each set of half-cells over multiple charge-discharge cycles was compared.

[0031] Figure 5A In an embodiment of the present disclosure, after cleaning copper-containing conductive layers of different materials with nitric acid, charge-discharge cycle tests were performed on each set of half-cells. The relationship between capacitance and coulombic efficiency and the number of cycles was compared for each set of half-cells over multiple charge-discharge cycles.

[0032] Figure 5BIn an embodiment of the present disclosure, after cleaning copper-containing conductive layers of different materials with hydrochloric acid, charge-discharge cycle tests were performed on each set of half-cells. The relationship between capacitance and coulombic efficiency and the number of cycles was compared for each set of half-cells over multiple charge-discharge cycles.

[0033] Figure 6A In an embodiment illustrating the present disclosure, a copper foil containing a copper conductive layer was treated with atmospheric pressure plasma. Anode-free full cells with the treated anode structure were subjected to charge-discharge cycling tests (the anode structure was not first charged, and therefore a lithium nitride film was not formed). The relationship between the discharge capacitance and coulombic efficiency of each anode-free full cell and the number of cycles was plotted against those with and without atmospheric pressure plasma treatment over multiple charge-discharge cycles.

[0034] Figure 6B In an embodiment illustrating the present disclosure, a copper mesh was used as the copper-containing conductive layer and treated with atmospheric pressure plasma. Charge-discharge cycling tests were conducted on anode-free full cells with the treated anode structure (the anode structure was not first charged, and thus a lithium nitride film was not formed). The relationship between the discharge capacitance and coulombic efficiency of each anode-free full cell and the number of cycles was plotted over multiple charge-discharge cycles, comparing groups treated with and without atmospheric pressure plasma treatment.

[0035] Figure 6C In an embodiment illustrating the present disclosure, a copper-containing conductive layer using copper foil was treated with atmospheric pressure plasma. A charge reaction then occurred on the anode structure to form a lithium nitride film. A charge-discharge cycle test was then conducted on anode-free full cells with the treated anode structure. The relationship between the discharge capacitance and coulombic efficiency of each anode-free full cell and the number of cycles was plotted over multiple charge-discharge cycles, comparing groups treated with and without atmospheric pressure plasma treatment.

[0036] Figure 6D Example in Figure 6C During the test, electron microscopy was used to observe the changes in the surface morphology of the copper foil in the groups with and without atmospheric plasma treatment during the charge and discharge stages.

[0037]

Explanation of symbols

[0038] 100, 200: Method

[0039] S110, S120, S130, S140, S150, S210, S220, S230, S240, S250, S260: Steps

[0040] N1: First side

[0041] N2: Second side

[0042] CL: copper-containing conductive layer

[0043] GI: Gas nozzle DETAILED DESCRIPTION

[0044] It will be appreciated that the following content provides different embodiments or examples that may implement different features of the subject matter of the present disclosure. The examples of specific components and arrangements are intended to simplify the present disclosure and are not intended to limit the present disclosure. Of course, these are merely examples and are not intended to be limiting. For example, the description below of a first feature being formed on a second feature includes the two being in direct contact, or the two being separated by other additional features rather than in direct contact. In addition, the present disclosure may repeat reference numbers and / or symbols in multiple embodiments. Such repetition is for simplicity and clarity and does not represent a relationship between the various embodiments and / or configurations discussed.

[0045] The terms used in this specification generally have their ordinary meanings in the art and in the context in which they are used. The examples used in this specification, including examples of any term discussed herein, are illustrative only and do not limit the scope and meaning of the present disclosure or any exemplary term. Similarly, the present disclosure is not limited to the embodiments provided in this specification.

[0046] It will be understood that although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used to distinguish one element from another element. For example, without departing from the scope of this embodiment, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0047] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0048] As used herein, the terms "include", "comprising", "having" and the like should be understood as open ended, that is, meaning including but not limited to.

[0049] Please refer to Figure 1 Some embodiments of the present disclosure provide a method 100 for preparing an anode structure, comprising steps S110 to S150.

[0050] It can be understood that method 100 forms a lithium nitride film on the copper-containing conductive layer by combining step S120 of treating the copper-containing conductive layer with atmospheric plasma at normal pressure (forming a copper nitride film on the surface of the copper-containing conductive layer) and step S150 of performing a charging reaction on the treated copper-containing conductive layer (converting the copper nitride film into a lithium nitride film). By providing the lithium nitride film, the reactivity of lithium during the charging and discharging process is improved, thereby improving the discharge capacitance of the battery, and serving as a protective layer to reduce impurity generation during charging and discharging, thereby extending the service life.

[0051] First, see step S110 , a copper-containing conductive layer is provided.

[0052] In some embodiments, the copper-containing conductive layer in step S110 includes copper foil, copper mesh, copper foam (a copper layer having multiple interconnected or disconnected pores uniformly distributed therein), or a combination thereof. Compared to other conductive materials, using copper as the conductive layer not only reduces costs but also offers superior conductivity.

[0053] In step S120 , a reaction gas including nitrogen is used to perform atmospheric plasma treatment on the copper-containing conductive layer to form a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure.

[0054] In some embodiments, the step of subjecting the copper-containing conductive layer to atmospheric plasma treatment at normal pressure includes cleaning the copper-containing conductive layer with an acidic solution. Since the copper in the copper-containing conductive layer is easily oxidized and forms copper oxide on the surface, which reduces electrochemical performance, cleaning the copper-containing conductive layer with an acidic solution can reduce the surface copper oxide content, thereby improving the capacitance, coulombic efficiency, and battery performance stability of the battery in which the anode structure is used.

[0055] In some embodiments, the acidic solution comprises hydrochloric acid, acetic acid, nitric acid, or a combination thereof. It is worth noting that, compared to cleaning with other acidic solutions, using nitric acid containing nitrogen atoms for cleaning can provide the battery with more stable capacitance and coulombic efficiency.

[0056] In some embodiments, during the step of cleaning the copper-containing conductive layer with an acidic solution, the concentration of the acidic solution is 0.005 mol / L (M) to 2 mol / L, for example, 0.005 M, 0.01 M, 0.05 M, 0.1 M, 0.2 M, 0.5 M, 1 M, 1.5 M, 2 M, or any value within the foregoing range. If the concentration is too low, the cleaning effect on copper oxide is limited, while if the concentration is too high, the copper-containing conductive layer may be corroded.

[0057] In some embodiments, the nitrogen-containing gas comprises nitrogen, ammonia, or a combination thereof. In some embodiments, the reaction gas further comprises another inert gas, such as argon. In some embodiments, the volume ratio of the nitrogen-containing gas to the other inert gas is 1:5 to 5:1, such as 1:5, 1:3, 1:1, 3:1, 5:1, or any value within the aforementioned range. If the volume ratio is too small, the copper nitride layer is not efficiently formed, while if the volume ratio is too large, the effect of increasing the amount of copper nitride layer formed is limited.

[0058] In some embodiments, the step of performing atmospheric plasma treatment on the copper-containing conductive layer comprises moving the gas nozzle in an S-shaped manner. For the atmospheric plasma treatment of the copper-containing conductive layer, a schematic diagram of the S-shaped movement can be seen in FIG. Figure 2 . Figure 2 The S-shaped movement pattern is shown in Figure 1. The gas showerhead GI moves from the first side N1 of the copper-containing conductive layer CL along the X-axis to the second side N2 relative to the first side N1, then moves a certain distance along the Y-axis. Then, it moves back along the X-axis from the second side N2 to the first side N1, repeating this cyclic movement. This S-shaped movement ensures that the reactant gas is evenly applied to the surface of the copper-containing conductive layer CL.

[0059] In some embodiments, the step of subjecting the copper-containing conductive layer to atmospheric plasma treatment at normal pressure comprises subjecting the copper-containing conductive layer to atmospheric plasma treatment at a plasma power of 170 W to 300 W (170 W, 200 W, 250 W, 300 W, or any value in the aforementioned range) and a gas flow rate of 17 L / min to 24 L / min (e.g., 17 L / min, 20 L / min, 24 L / min, or any value in the aforementioned range). If the plasma power is too high, the cost is high but the improvement in reaction efficiency is limited. If the plasma power is too low, the reaction efficiency is limited. If the gas flow rate is too high, the improvement in reaction efficiency is limited. If the gas flow rate is too low, the reaction time is too long.

[0060] It is understandable that if a copper nitride film is formed by plasma sputtering or evaporation, the production cost is high and the structure of the copper nitride film is too dense. Since the structure of the copper nitride film is too dense, the replacement of copper ions in the copper nitride will be more difficult, resulting in limited efficiency in the subsequent conversion to lithium nitride, and the process will take considerable time and cost. In contrast, the copper nitride film formed by atmospheric plasma treatment at normal pressure not only has a lower processing cost, but also has a lower density. It is easier to convert into lithium nitride during the subsequent charging process, and can achieve a better lithium nitride conversion rate.

[0061] Therefore, please refer to step S130 to step S150.

[0062] Step S130: Provide a lithium-containing electrode and a half-cell electrolyte. Step S140: Use the transitional anode structure as a working electrode and the lithium-containing electrode as an auxiliary electrode, and assemble the working electrode, auxiliary electrode, and half-cell electrolyte into a half-cell system. Step S150: Connect the transitional anode structure to the negative electrode (the negative electrode of an external power source), and connect the lithium-containing electrode to the positive electrode (the positive electrode of an external power source), and charge the half-cell system to convert the copper nitride in the copper nitride film into lithium nitride, thereby obtaining an anode structure comprising a copper-containing conductive layer and a lithium nitride film covering the copper-containing conductive layer.

[0063] In some embodiments, the lithium-containing electrode comprises a lithium metal sheet, a lithium-containing compound, or a combination thereof. When the lithium metal sheet is selected, the lithium metal sheet has a higher purity of lithium, which can achieve better charging efficiency in the charging reaction of step S150.

[0064] In some embodiments, the half-cell electrolyte contains lithium ions, which can enhance the efficiency of the reversible reaction of lithium ion deposition and desorption during the charging reaction in step S140. For example, the half-cell electrolyte contains lithium difluoro(oxalato)borate (LiDFOB).

[0065] In some embodiments, the step of charging the half-cell system comprises charging the half-cell system with a current of 0.1 mA / cm² to 0.5 mA / cm² until the voltage reaches 0 V. In some embodiments, the charging is performed with a current of 0.1 mA / cm², 0.2 mA / cm², 0.3 mA / cm², 0.4 mA / cm², 0.5 mA / cm², or any value within the foregoing ranges. If the current is too low, the charging time is too long. If the current is too high, the lithium nitride film formation efficiency and uniformity are poor.

[0066] It is understood that, compared to directly using a copper-containing conductive layer with a copper nitride layer as the anode structure, further performing the charging step (S150) to convert the copper nitride layer into a lithium nitride layer can enhance the reactivity of lithium deposition during the charge and discharge process, thereby increasing discharge capacitance. Furthermore, the lithium nitride layer acts as a protective layer, reducing the formation of impurities (lithium-containing branched compounds) formed by electrolyte reactions, thereby extending the battery's service life.

[0067] Some embodiments of the present disclosure also provide a battery comprising an anode structure prepared using method 100, a cathode structure, and an electrolyte. The cathode structure comprises lithium metal. The electrolyte is electrically connected to the anode structure and the cathode structure. The anode structure prepared using method 100 can achieve improved discharge capacitance and extend battery life.

[0068] In some embodiments, the cathode structure further comprises nickel, cobalt, iron, aluminum, and manganese. For example, the cathode structure comprises LiNi 0.8 Mn 0.1 Co 0.1 In some embodiments, the electrolyte contains lithium ions. By selecting a cathode structure and electrolyte containing lithium metal and lithium ions, this can be combined with an anode structure to form an anode-free lithium battery (the active ingredient in the anode structure does not contain lithium metal or lithium ions. Lithium ions are present in the cathode structure. During the charging reaction, the lithium ions are deposited on the anode structure in the form of lithium metal, serving as the anode active ingredient, AFLMB).

[0069] Please refer to Figure 3 Some embodiments of the present disclosure further provide a method 200 for preparing an anode structure, comprising steps S210 to S260. Figure 1 Method 100 and Figure 3 The difference between the steps of the method 200 is that Figure 1 The steps include step S120 of atmospheric plasma treatment at normal pressure, Figure 3 The steps include step S220 of pre-cleaning the copper-containing conductive layer using an acidic solution.

[0070] In method 200, the copper-containing conductive layer is first cleaned with an acidic solution to remove copper oxide on the surface, and then a copper nitride layer is formed on the copper-containing conductive layer. This can improve the capacitance, coulombic efficiency, and stability of the battery performance of the battery in which the anode structure is applied.

[0071] Some embodiments of the present disclosure also provide a battery comprising an anode structure prepared by method 200, a cathode structure, and an electrolyte. The cathode structure comprises lithium metal. The electrolyte is electrically connected to the anode structure and the cathode structure. The details and functions of the various components of the battery are as previously described and are not further elaborated here.

[0072] A series of examples of condition tests for the preparation method of the anode structure are provided below to specifically illustrate some embodiments of the present disclosure.

[0073] Example 1: Testing of cleaning conditions for copper-containing conductive layers

[0074] 1. For copper foil

[0075] First, a copper foil is provided as a copper-containing conductive layer, and the copper foil is cleaned using acidic solutions with different conditions. The conditions of the acidic solutions are shown in Table 1 below.

[0076] Table 1

[0077]

[0078] Next, the copper foils obtained after different cleaning conditions were used as working electrodes, lithium foils as auxiliary electrodes, and 1M lithium difluorooxalatoborate (LiDFOB) dissolved in ethylene carbonate (EC) and dimethyl carbonate (DMC) as the half-cell electrolyte (the volume ratio of EC to DMC was 1:1). After assembling the working electrode, auxiliary electrode, and half-cell electrolyte into a half-cell system, multiple charge and discharge tests were performed at a charge voltage of 0 V, a discharge voltage of 3 V, and a charge and discharge current of 0.02 mA / cm². The relationship between the capacitance and coulombic efficiency of each half-cell and the number of cycles was recorded. The results are shown in the figure. Figure 4 .

[0079] Figure 4 The results show that compared with the groups cleaned with hydrochloric acid (such as the 1M HCl group and the 1M HCl+0.1M HNO3 group), the groups cleaned with nitric acid (0.1M HNO3 group and 0.01M HNO3 group) showed smaller fluctuations in capacitance and coulombic efficiency before and after charge and discharge tests, indicating more stable performance. This performance difference may be related to the fact that nitric acid contains nitrogen atoms. Therefore, in addition to cleaning, nitric acid can also provide nitrogen atoms to assist in the formation of the subsequent copper nitride layer.

[0080] In addition, by comparing nitric acid of different concentrations, it can be found that when the concentration of nitric acid is higher, the initial capacitance and coulombic efficiency are higher.

[0081] 2. For copper mesh, foam copper and copper foil

[0082] To further test the electrochemical performance of the anode structures prepared by using different copper materials as the copper-containing conductive layer [comparison included three different copper materials: copper mesh, foam copper, and copper foil. The copper mesh group was further divided into groups based on thickness: copper mesh (thickness 200 microns), copper mesh (thickness 80 microns), and copper mesh (thickness 30 microns)] and cleaning with different acidic solutions, each group of copper-containing conductive layers was pre-cleaned with nitric acid or hydrochloric acid, and then multiple charge and discharge tests were performed in a manner similar to the above point 1. The capacitance of each half-cell and the relationship between coulombic efficiency and cycle number were recorded. The results are shown in the figure. Figure 5A (nitric acid cleaning) and Figure 5B (Hydrochloric acid cleaning).

[0083] Figure 5A It is shown that compared with the copper foil group that has not been cleaned with nitric acid, the copper mesh, foam copper and copper foil groups cleaned with nitric acid can reduce the surface copper oxide content, thereby exhibiting higher capacitance and coulombic efficiency. Figure 5B also showed a similar trend.

[0084] Furthermore, the comparison Figure 5Aas well as Figure 5B As can be seen, compared to cleaning with hydrochloric acid, the half-cell performance of the copper mesh (thickness 220 microns) and copper foam groups treated with nitric acid was more stable. Therefore, 0.1M nitric acid was used as the cleaning condition in the subsequent tests.

[0085] Example 2: Electrochemical performance of anode-free full cell

[0086] 1. Copper foil anode-free full battery / without first forming lithium nitride film

[0087] Copper foil is used as the copper conductive layer. After being cleaned with 0.1M nitric acid, atmospheric pressure plasma jet (APPJ) is used. A reaction gas containing nitrogen and argon (nitrogen to argon volume ratio of 1:1) is used. The plasma power is 170 to 300 watts and the gas flow rate is 17 liters / minute to 24 liters / minute. The gas nozzle is moved in an S-shaped manner to perform atmospheric pressure plasma treatment on the cleaned copper foil, forming an anode structure with a copper nitride film covering the copper foil.

[0088] Then, the anode structure was assembled into an anode-free full cell (cathode structure: aluminum sheet covered with NCM 811 (LiNi 0.8 Co 0.1 Mn 0.1 O2): Electrolyte: Same as the half-cell electrolyte in Example 1 above. After forming the anode structure, a charge-discharge cycle test was performed directly. Since the anode structure was not first charged, a lithium nitride film was not formed. The charge and discharge cycle tests were conducted at a charge voltage of 4.2 volts, a discharge voltage of 3 volts, and a charge and discharge current of 0.02 milliamperes per square centimeter. During the cycle test, the groups treated with and without atmospheric plasma treatment were compared. The relationship between the discharge capacitance and coulombic efficiency of each group of batteries over multiple charge and discharge cycles is shown in the graph below. Figure 6A The initial charging capacitance, initial discharging capacitance, and reversibility (initial discharging capacitance / initial charging capacitance x 100%, initial coulombic efficiency) are shown in Table 2 below.

[0089] Table 2

[0090]

[0091] Figure 6A As shown in Table 2, compared with the group without plasma treatment, the group treated with atmospheric pressure plasma maintained a higher value of the overall discharge capacitance during the charge and discharge cycle, and the stability of the coulombic efficiency was higher.

[0092] 2. Copper mesh without anode full battery / not precharged (no lithium nitride film formed first)

[0093] The copper-containing conductive layer of the anode-free full battery uses a copper mesh. After cleaning the copper mesh with 0.1M nitric acid, a jet-type atmospheric plasma (APPJ) is used with a reaction gas containing nitrogen and argon (the volume ratio of nitrogen to argon is 1:1), a plasma power of 170 to 300 watts, and a gas flow rate of 17 liters / minute to 24 liters / minute. The gas nozzle is moved in an S-shaped manner to perform atmospheric plasma treatment on the cleaned copper mesh to form an anode structure with a copper nitride film covering the copper mesh.

[0094] Next, after forming the anode structure, the anode structure was assembled into an anode-free full cell in a manner substantially similar to that of point 1 in Example 2 above. Charge and discharge cycle tests were then conducted to compare the groups treated with and without atmospheric plasma treatment. The relationship between the discharge capacitance and coulombic efficiency of each group of cells over multiple charge and discharge cycles is shown in the graph below. Figure 6B The initial charging capacitance, initial discharging capacitance, and reversibility (initial discharging capacitance / initial charging capacitance x 100%, initial coulombic efficiency) are shown in Table 3 below.

[0095] Table 3

[0096]

[0097] Figure 6B As shown in Table 3, compared with the group without plasma treatment, the group treated with atmospheric pressure plasma has a higher reversibility rate, and the overall discharge capacitance and coulombic efficiency in the charge and discharge cycle are higher, and can sustain more cycles, with a longer cycle life.

[0098] 3. Copper foil anode-free full battery / precharge (form lithium nitride film first)

[0099] The copper-containing conductive layer of the anode-free full battery is made of copper foil. After cleaning the copper foil with 0.1M nitric acid, an atmospheric pressure plasma jet (APPJ) is used. The reaction gas contains nitrogen and argon (the volume ratio of nitrogen to argon is 1:1), the plasma power is 170 to 300 watts, and the gas flow rate is 17 liters / minute to 24 liters / minute. The gas nozzle is moved in an S-shaped manner to perform atmospheric pressure plasma treatment on the cleaned copper foil to form an anode structure with a copper nitride film covering the copper foil.

[0100] Next, the anode structure served as the working electrode, lithium foil as the auxiliary electrode, and 1M lithium difluorooxalatoborate (LiDFOB) dissolved in ethylene carbonate (EC) and dimethyl ether (DME) as the half-cell electrolyte (the volume ratio of EC to DME was 1:1). The working electrode, auxiliary electrode, and half-cell electrolyte were assembled into a half-cell system and charged at a current of 0.2 milliamperes per square centimeter until the voltage reached 0 volts. During the charging process, lithium ions replaced copper ions in the copper nitride film, converting the copper nitride film into a lithium nitride film, resulting in an anode structure (with a lithium nitride film covering the copper foil).

[0101] Then, the anode structure was assembled into an anode-free full cell (cathode structure: aluminum sheet covered with NCM 811 (LiNi 0.8 Co 0.1 Mn 0.1 O2): Electrolyte: Same as the half-cell electrolyte in Example 1 above. A charge-discharge cycle test was conducted under the same conditions as in Example 2, point 1. During the cycle test, the groups treated with atmospheric plasma and those without were compared. The relationship between the discharge capacitance and coulombic efficiency of the anode-free full cell and the number of cycles was plotted over multiple charge-discharge cycles. See the results for details. Figure 6C .

[0102] Figure 6C The results show that compared with the group without plasma treatment, the discharge capacitance of the group treated with atmospheric pressure plasma is higher, and it can sustain more cycles and has a longer cycle life.

[0103] In addition, compared Figure 6A as well as Figure 6C , it can be found that Figure 6A The anode structure is not pre-charged (no lithium nitride film is formed first) without anode full battery ( Figure 6A ), the initial discharge capacitance was about 145 mA / g, and after 45 cycles, the coulombic efficiency fluctuated significantly and became unstable; Figure 6C The results show that the anode-free full cell with a pre-charged anode structure has an initial discharge capacitance of approximately 190 mA / g, and the coulombic efficiency remains stable after 80 cycles. Therefore, pre-charging the anode structure (forming a lithium oxide layer first) can give the anode-free full cell a higher capacitance and better coulombic efficiency stability.

[0104] On the other hand, after the first charge, the morphology of the copper foil surface was observed by electron microscopy in the groups with and without atmospheric plasma treatment. The results are shown in the table. Figure 6D .

[0105] Figure 6D The results show that copper foil surfaces without plasma treatment are susceptible to reaction with the electrolyte during charge and discharge, generating impurities containing lithium branched compounds. In contrast, copper foil surfaces treated with atmospheric pressure plasma, due to the protective lithium nitride layer, are less susceptible to impurities, thus extending the battery's lifespan.

[0106] Although the present disclosure has been described in detail with reference to certain embodiments, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the embodiments described herein.

Claims

1. A method for preparing an anode structure, characterized in that: Include: providing a copper-containing conductive layer; performing atmospheric plasma treatment on the copper-containing conductive layer using a reaction gas containing nitrogen to form a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure; Providing lithium-containing electrodes and half-cell electrolytes; The transitional anode structure is used as a working electrode, and the lithium-containing electrode is used as an auxiliary electrode, and the working electrode, the auxiliary electrode and the half-cell electrolyte are assembled into a half-cell system; as well as The transitional anode structure is connected to the negative electrode, and the lithium-containing electrode is connected to the positive electrode, and the half-cell system is charged, so that the copper nitride in the copper nitride film is converted into lithium nitride, thereby obtaining an anode structure, which includes the copper-containing conductive layer and the lithium nitride film covering the copper-containing conductive layer.

2. The method according to claim 1, wherein Before the step of performing the atmospheric plasma treatment on the copper-containing conductive layer, the method includes cleaning the copper-containing conductive layer with an acidic solution.

3. The method according to claim 2, wherein The acidic solution comprises hydrochloric acid, acetic acid, nitric acid or a combination thereof.

4. The method according to claim 2, wherein The concentration of the acidic solution is 0.005 mol / L to 2 mol / L.

5. The method according to claim 1, wherein The step of performing the atmospheric plasma treatment on the copper-containing conductive layer comprises moving the gas nozzle in an S-shaped manner to perform the atmospheric plasma treatment on the copper-containing conductive layer.

6. The method according to claim 1, wherein The step of charging the half-battery system includes charging with a current of 0.1 mA / cm2 to 0.5 mA / cm2 until the voltage reaches 0 volts.

7. A battery, characterized in that: Include: The anode structure prepared by the method of claim 1; a cathode structure comprising lithium metal; and The electrolyte is electrically connected to the anode structure and the cathode structure.

8. The battery according to claim 7, wherein The cathode structure further comprises nickel, cobalt, manganese, iron and aluminum.

9. The battery according to claim 7, wherein The electrolyte contains lithium ions.

10. A method for preparing an anode structure, characterized in that: Include: providing a copper-containing conductive layer; cleaning the copper-containing conductive layer using an acidic solution; forming a copper nitride film on the copper-containing conductive layer to obtain a transitional anode structure; Providing lithium-containing electrodes and half-cell electrolytes; The transitional anode structure is used as a working electrode, and the lithium-containing electrode is used as an auxiliary electrode, and the working electrode, the auxiliary electrode and the half-cell electrolyte are assembled into a half-cell system; as well as The transitional anode structure is connected to the negative electrode, and the lithium-containing electrode is connected to the positive electrode, and the half-cell system is charged, so that the copper nitride in the copper nitride film is converted into lithium nitride, thereby obtaining an anode structure, which includes the copper-containing conductive layer and the lithium nitride film covering the copper-containing conductive layer.

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