Process for producing an anode for lithium batteries

Abstract

The invention provides a process for producing an anode for a lithium battery. The process comprises providing a current collector, depositing a layer of protective material on a surface of the current collector, depositing a layer of a lithiophilic material on a surface of the protected current collector, and depositing a layer of lithium material in molten form on the layer of lithiophilic material, the lithiophilic material thus reacting with the molten lithium material to form a layer of active anode material. The current collector and / or at least one other layer of the anode may comprise a continuous 3D structure. The protective material deposited on the current collector forms a barrier between the current collector and the lithium in the active anode material, the formation of cracks in the current collector thus being avoided.

Description

METHOD FOR PRODUCING AN ANODE FOR LITHIUM BATTERIES CROSS-REFERENCE TO RELATED REQUESTS This application claims the benefit of U.S. Provisional Patent Application No. 63 / 299247 filed on January 13, 2022. The content of that application is incorporated herein in its entirety for reference. FIELD OF INVENTION

[0001] The present invention relates generally to methods for producing anodes for lithium batteries. More specifically, the invention relates to a method for producing an anode in which the active anode material is formed following a reaction between a lithiophilic material and a molten lithium material, or following the deposition of the lithium material onto a lithiophilic surface. The current collector and / or at least one other layer of the anode may comprise a continuous 3D structure. CONTEXT OF THE INVENTION

[0002] Lithium metal, with a theoretical specific energy of 3860 mAh / g, is a good anode material for an energy storage system (ESS) or battery, compared, for example, to a material such as graphite, which has a theoretical specific energy of 372 mAh / g.

[0003] A thin sheet of lithium (Li) is needed to increase the battery's energy density and reduce the anode's production cost. However, Li has low mechanical strength and low electronic conductivity (less than 5 times and 3 times that of copper and aluminum, respectively). Consequently, a thin, self-supporting Li is difficult to produce and handle. It is known in the art to use a thin layer of Li deposited on a conductive substrate. Typically, a substrate, also called a current collector, is chosen that exhibits good mechanical properties and good electronic conductivity. Even a Li layer as thin as 4 to 5 microns on the substrate is a better solution than using a self-supporting Li.

[0004] Methods for depositing a thin layer of lithium onto a metallic substrate are known in the art. Such methods include, for example, physical vapor deposition (PVD). However, several drawbacks are associated with PVD, such as the relatively slow deposition rate and the overall high cost of the technique.

[0005] It has also been observed that when a layer of lithium is deposited on the current collector, an interaction occurs between the lithium and the conductive material, leading to the formation of cracks in the current collector. This is described in more detail below. Crack formation in the current collector becomes particularly prevalent when a thinner, more desirable current collector is used, and also when other deposition techniques are employed that involve the use of lithium at elevated temperatures.

[0006] The inventors are aware of the following documents: US 2020 / 099039, WO 2020 / 240553, WO 2020 / 210913, WO 2014 / 201569, US 7 964 307B2, US 2021 / 0218032A1, US 11 437 624B2, WO 2022 / 077120A1, and US 2022 / 0328803.

[0007] There remains a need for efficient and cost-effective processes to produce anodes for lithium batteries. In particular, there is a need for such processes that allow for Li deposition techniques other than PVD, and that do not lead to damage to the current collector. SUMMARY OF THE INVENTION

[0008] The inventors have devised a method for producing an anode for lithium batteries. The method comprises: supplying a current collector, forming a protective layer on it, depositing a lithiophilic material on the protective layer, and depositing molten lithium material on the lithiophilic layer. The lithiophilic material and the molten lithium material then react to form the active anode material. The current collector and / or at least one other layer of the anode may have a continuous 3D structure on a surface. The method may also include plasma treatment, which can lead to the formation of a lithiophilic surface. The protective material deposited on the current collector acts as a barrier between the current collector and the lithium in the active anode material, thus preventing the formation of cracks in the current collector.

[0009] In embodiments of the invention, the deposition of the lithiophilic material on the protective layer is followed by a plasma treatment leading to a plasma-treated lithiophilic material, before the deposition of the molten lithium material.

[0010] In embodiments of the invention, the protective layer is subjected to plasma treatment leading to the formation of a lithiophilic surface, on which the molten lithium material is deposited.

[0011] Plasma treatment can be atmospheric pressure thermal plasma or any other suitable plasma treatment.

[0012] In embodiments of the invention, the current collector comprises a continuous 3D structure formed on its surface. Furthermore, at least one other layer of the anode, including the protective layer, the lithiophilic surface, the anode active material layer, and the surface treatment agent layer, may comprise a continuous 3D structure. The continuous 3D structure may be formed by electrochemical deposition of a conductive material. Alternatively, for example, with regard to the current collector, the continuous 3D structure may be formed by imparting a certain roughness to its surface using a technique that may include mechanical and / or laser treatment, electrochemical oxidation, chemical etching, or any other suitable technique.

[0013] In embodiments of the invention, the molten lithium material comprises lithium or an alloy thereof.

[0014] In embodiments of the invention, an anode is provided comprising a current collector, a protective layer deposited on the current collector, and an active anode layer formed by a reaction between a lithiophilic material and molten lithium, or formed by the deposition of lithium onto a lithiophilic surface. In embodiments of the invention, the anode is single-sided or double-sided. In embodiments of the invention, the current collector has a thickness of approximately 4 to 5 µm.

[0015] In embodiments of the invention, an apparatus adapted to implement the process described herein to produce the anode described herein is provided.

[0016] In embodiments of the invention, the lithium battery is a lithium-ion battery or an all-solid-state battery.

[0017] The invention thus provides the following in accordance with certain aspects thereof: (1). A method for producing an anode for a lithium battery, comprising: a) providing a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c) depositing a layer of lithiophilic material on a surface of the protected current collector; and d) depositing a layer of molten lithium material on the lithiophilic material layer, the lithiophilic material reacting with the molten lithium material to form an active anode material layer. (2). A method for producing an anode for a lithium battery, comprising: a) providing a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c) depositing a layer of lithiophilic material on a surface of the protected current collector, then c1) subjecting the layer of lithiophilic material to plasma treatment to obtain a plasma-treated layer of lithiophilic material; and d) depositing a layer of molten lithium material on the plasma-treated layer of lithiophilic material, the lithiophilic material reacting with the molten lithium material to form an active anode material layer. (3). A method for producing an anode for a lithium battery, comprising: a) supplying a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c1) subjecting the protected current collector to plasma treatment to obtain a plasma-treated protected current collector having a lithiophilic surface; and d) depositing a layer of molten lithium material on the lithiophilic surface, thereby forming an active anode material layer. (4). A method according to any one of points (1) to (3) above, further comprising a step a1) the formation of a continuous 3D structure on a surface of the current collector to obtain a textured current collector before carrying out step b). (5). A method according to any one of points (1) to (4) above, further comprising a step b1) the formation of a continuous 3D structure on a surface of the protected current collector to obtain a textured protected current collector before carrying out step c) or c1). (6). A process according to any one of points (1) to (5) above, further comprising (e) the deposition of a layer of a surface treatment agent on the layer of anode active material formed. (7). A method according to any one of points (1) to (6) above, further comprising a step d1) the formation of a continuous 3D structure on a surface of the anode material layer before carrying out step e). (8). A process according to any one of points (1) to (7) above, further comprising a step e1) the formation of a continuous 3D structure on a surface of the surface treatment agent layer. (9). A method according to any one of points (1) to (8) above, wherein steps a1), b), b1), c), c1), d), d1), e), and e1) are carried out on both sides of the current collector and a double-sided anode is produced, optionally steps a1), b), b1), c), c1), d), d1), e), and e1) are all carried out on one side of the current collector and then on the other side of the current collector; optionally each of steps a1), b), b1), c), c1), d), d1), e), and e1) is carried out simultaneously on one side of the collector and then on the other side of the current collector. (10). A method according to any one of points (1) to (9) above, wherein steps a1) and b1) each independently comprise an electrochemical deposition of a conductive material on the surface of the current collector or on the surface of the protected current collector, optionally the conductive material is the same material as the current collector; optionally the conductive material is a different material from the current collector. (11). A method according to any one of points (1) to (10) above, wherein steps a1) and b1) each independently comprise the provision of a certain roughness on the surface of the current collector, optionally steps a1) and b1) each independently comprise mechanical and / or laser treatment, electrochemical oxidation, chemical etching, or any suitable technique. (12). A process according to any one of points (1) to (110) above, wherein step b) comprises electrochemical deposition, autocatalytic plating, or any suitable technique. (13). A process according to any one of points (1) to (12) above, wherein step (c) includes electrochemical oxidation or reduction, or any suitable technique. (14). A process according to any one of points (1) to (13) above, wherein the plasma treatment in step c1) is an atmospheric pressure thermal plasma. (15). A process according to any one of points (1) to (14) above, wherein step (d) includes infiltration processes, wave welding, the use of heated nozzles, the use of anilox cylinders, or any suitable technique. (16). A process according to any one of points (1) to (15) above, wherein at least one drying step is carried out after any one of steps a1), b), b1), c), d), and e). (17). A process according to any one of points (1) to (16) above, wherein the molten lithium material is at a temperature between about 180°C and about 400°C, optionally the molten lithium material is at a temperature of about 210°C. (18). A method according to any one of points (1) to (17) above, wherein the current collector comprises a material that is Cu, Al, Ni, Ti, C, stainless steel, a conductive polymer, or a combination thereof, optionally the current collector comprises Cu, Al, or carbon-coated aluminum. (19). A process according to any one of points (1) to (18) above, wherein the protective material comprises Ni, Co, Cr, Fe, Ti, or a combination thereof, optionally the protective material comprises Ni. (20). A process according to any one of points (1) to (19) above, wherein the lithiophilic material comprises CuO, Cu2O, ZnO, MnO2, SnO2, Cu, Au, Mg, Al, In, B, Zn, Sn, Si, SiO2, SiO2 x , a metallic fluoride, a metallic boride, or a combination thereof, possibly the lithiophilic material includes ZnO, Zn, or Sn. (21). A method according to any one of points (1) to (20) above, wherein the lithiophilic surface has a continuous 3D structure, optionally the lithiophilic surface comprises Ni. (22). A process according to any one of points (1) to (21) above, wherein the molten lithium material comprises lithium or an alloy thereof, optionally the molten lithium material is lithium metal; optionally the lithium alloy is a binary alloy such as Li-Mg, Li-Al, Li-Na, Li-Si, Li-Sn, Li-Zn, Li-Ag, Li-K, Li-B, or any other suitable binary lithium alloy; or the lithium alloy is a ternary alloy such as Li-Al-Na, Li-Mg-Na, Li-Al-Si, Li-Mg-Si, or a ternary alloy comprising elements such as Cu, Zn, Sn, Ca, Sr, or any other suitable ternary lithium alloy. (23). A process according to any one of points (1) to (16) above, wherein the surface treatment agent comprises Ag, Zn, SiO x , Sn, Si, l_i2CO3, LiF, carbon black, carbon nanofibre, graphene, or any other suitable surface treatment agent. (24). A method according to any one of points (1) to (23) above, wherein the lithium battery is a lithium-ion battery or an all-solid-state battery. (25). Anode produced by the process as defined in any one of points (1) to (24) above. (26). Anode for a lithium battery, comprising: a current collector; a layer of protective material deposited on the current collector; and an active anode material which is formed as a result of a reaction between a lithiophilic material and a lithium material in molten form, optionally the active anode material is formed as a result of the deposition of the lithium material on a lithiophilic surface. (27). Anode according to point (25) or (26) above, in which there is substantially no physical or chemical interaction between the current collector and the active anode material. (28). Anode according to any one of the points (25) to (27) above, which is single-sided or double-sided. (29). Anode according to any one of the points (25) to (28) above, in which the current collector has a thickness of between about 4 and about 5 pm. (30). Apparatus adapted to produce the anode as defined in any one of points (25) to (29) above. (31). Use of the anode as defined in any one of points (25) to (29) above, in the manufacture of a lithium battery. (32). Method for manufacturing a lithium battery, comprising the use of the anode as defined in any one of points (25) to (29) above. (33). Lithium battery comprising the anode as defined in any of points (25) to (29) above, optionally the lithium battery is a lithium-ion battery or an all-solid-state battery.

[0018] Other objects, advantages and features of the present invention will become more apparent from the following non-limiting description of particular embodiments thereof, given solely by way of example with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The patent or application file must contain at least one color drawing. Copies of this patent or the publication of the patent application with color drawing(s) will be provided by the Office upon request and payment of the necessary fees.

[0020] In the attached drawings:

[0021] Figure 1: EDS analysis of the cross-section of a sample consisting of a copper current collector sheet coated with a 50 nm thick Zn layer as a lithophile material and contacted with molten Li. A) an SEM image of the cross-section; and B) the linear scanning EDS analysis of the cross-section as a function of depth.

[0022] Figure 2: Anode according to the invention illustrating a single-sided anode and a double-sided anode.

[0023] Figure 3: The appearance of the copper foil at the back face of each sample as a function of time for Cu-Zn-Li and Cu-Ni-Zn-Li.

[0024] Figure 4: SEM and EDS analyses of the back face of Cu-Ni-Zn-Li and Cu-Zn-Li samples after 30 seconds of contact with molten Li.

[0025] Figure 5: Variation of the contact angle of molten Li on Cu-Ni and Cu-Ni-Zn substrates of different Zn layer thicknesses.

[0026] Figure 6: Variation of the contact angle of molten Li on Cu-Ni-Zn substrates of different Zn layer thicknesses after 10 and 30 seconds of contact.

[0027] Figure 7: Variation of the contact angle of molten Li on Cu-Ni and Cu-Ni-Sn substrates of different Sn layer thicknesses.

[0028] Figure 8: Photograph of the surface of the Cu foil sample after electrodeposition of Ni (a), electrodeposition of ZnO (b), and application of Li (c).

[0029] Figure 9: Variation of the contact angle for Cu-Ni and Cu-Ni-Sn (40 nm) with molten Li and that of Cu-Ni-Sn (40 nm) with the Li-Mg alloy.

[0030] Figure 10: SEM image of the sample (after cryofracture) showing a thin layer of Li with a thickness of 5 pm with good uniformity (variation less than ±1 pm).

[0031] Figure 11: EDS linear scanning analysis on the cross section as a function of the depth of the Cu-Ni-Sn-Li-Zn sample.

[0032] Figure 12: Lithiophile activity of the different Cu-Ni substrates expressed as the total surface area of ​​the molten Li after two minutes of spreading time. DESCRIPTION OF ILLUSTRATIVE METHODS OF IMPLEMENTATION

[0033] Before the present invention is described in more detail, it should be understood that the invention is not limited to the particular embodiments described below, as variations of these embodiments may be made and always fall within the scope of the appended claims. It should also be understood that the The terminology used is intended to describe specific embodiments and is not meant to be limiting. Instead, the scope of the present invention will be established by the attached claims.

[0034] To provide a clear and consistent understanding of the terms used in this specification, several definitions are provided below. Furthermore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as that commonly understood by a person skilled in the art to whom this disclosure relates.

[0035] The use of the word "a" or "an" when used in conjunction with the term "including" in the claims and / or specification can mean "one," but it is also consistent with the meanings of "one or more," "at least one," and "one or more than one." Similarly, the word "other" can mean at least a second or more.

[0036] As used in this specification and the claim(s), the words "including" (and any form of including, such as "include" and "include"), "having" (and any form of having, such as "have" and "has"), "comprising" (and any form of comprising, such as "comprise" and "include") or "containing" (and any form of containing, such as "contain" and "contains"), are inclusive or open and do not exclude additional unstated elements or operational steps.

[0037] As used here, the term "textured current collector" refers to a current collector that has at least one surface comprising a continuous 3D structure formed on it. The continuous 3D structure can be formed by electrochemical deposition of a conductive material, or by a technique including mechanical and / or laser processing, electrochemical oxidation (dissolution), chemical etching, or any other suitable technique. It should be noted that the term "textured" is also used here in relation to any other layer of the anode that comprises a continuous 3D structure. Such a layer includes, for example, the protective layer, the anode active material layer, and the surface treatment agent layer. It should also be noted that the term "rough" is used in the same sense as the term "textured." The terms "textured" and "rough" are therefore used interchangeably.

[0038] As used here, the term "lithiophilic surface" refers to a surface that has an affinity for lithium. Such a surface can be a current surface The collector incorporates a protective layer of material. Furthermore, the surface may include a continuous 3D structure. The lithipyl property can be imparted to the surface following plasma treatment.

[0039] The inventors have designed a process for producing an anode for lithium batteries.

[0040] Our data confirm that when molten Li metal is applied to a Cu or Al foil (even at temperatures as low as 210°C), the surface of the current-collecting metal begins to form an alloy. Once the applied layer of molten Li solidifies, fragments of the current-collecting material can be found within the Li layer or on its surface. Figure 1 shows the EDS analysis of the cross-section of a sample consisting of a copper current-collecting foil that had been coated with a 50 nm thick Zn layer as a lithophile material and contacted with molten Li. Figure 1A is a SEM image of the cross-section, and Figure 1B shows the EDS linear scanning analysis across the cross-section as a function of depth.The Si signal is due to the resin used to prepare the sample for cryo-microtomy, and it is normal to see the detection of the C signal in this type of analysis due to the inevitable presence of contamination. The oxygen signal indicates where the top of the deposited Li layer begins (at approximately 1.4 pm) and where it ends (at approximately 4.8 pm). As can be seen, a very strong copper signal is detected at the surface of the deposited Li layer, showing that Cu fragments have detached from the surface of the Cu foil and formed intermetallic particles on the upper part of the Li layer.

[0041] It should be noted that in Figure 2, the reference numbers 1 to 5 identify an element of the anode as follows: 1 - current collector substrate, 2 - textured layer, 3 - protective layer, 4 - Li material, and 5 - surface treatment layer.

[0042] In cases where the current collector thickness is very small, significant holes begin to appear in the current collector material due to the interaction between the lithium layer and the current collector surface. This can be a significant drawback, especially when the goal is to use very thin current collector sheets (e.g., 4–5 µm) to minimize anode production costs and maximize the battery's specific and volumetric energy density.

[0043] It should be noted that different categories of lithiophilic materials can be deposited onto the barrier layer by electrochemical processes under controlled conditions (in terms of thickness and morphology of the deposit) in a time-efficient and scalable electrochemical setup. Depending on the nature of the lithiophilic material, at the deposition stage, the current collector can receive a cathodic current (becoming the cathode electrode during lithiophilic deposition) or an anodic current. Therefore, the current collector can be used as a cathode (for the deposition of elements such as Zn, Sn, Si, metal borides, or oxides such as ZnO, MnO2, or SnO2), or as an anode (for the deposition or formation of compounds such as CuO, Cu2O, SnO2, or MnO2).

[0044] The advantages of electrochemical deposition compared to other approaches are as follows: • Compared to the PVD, it is more profitable and much faster • Compared to wet chemistry and heat treatments, the thickness is better controlled and more precise, and the process is much faster (several seconds or minutes instead of several hours). • It is easier to control the exact areas where the lithiophane material is deposited, which in turn allows for better control of where the Li layer will be deposited • Scaling up a roll-to-roll electrochemical lithiophilic deposit is easier and more cost-effective. Example 1

[0045] Two sets of current collectors were prepared using a 5 µm thick copper foil. In one set, a 40 nm layer of Zn was deposited onto the copper foil in an electrolytic cell to prepare Cu-Zn foil samples. For the second set, a 300 nm layer of Ni (the thickness was estimated using a quartz crystal microbalance) was electrochemically deposited prior to the 40 nm Zn layer to prepare Cu-Ni-Zn foil samples. To evaluate the effect of the interaction between molten Li and the Cu foil in the presence of a lithophile material such as Zn, both sets of prepared samples were tested by contact with the same amount of molten Li was applied under the same conditions. For each test (performed in an Ar glove box equipped with purification units to ensure H2O, O2, and N2 levels below 1 ppm), approximately 0.1 g of molten Li (prepared by heating Li to 250°C in a stainless steel syringe and applied using a mechanically operated piston) was deposited onto the surface of the sample (approximately 14 cm²). 2 The sample was placed on a sample holder that ensured the sample was flat and allowed its temperature to be controlled at approximately 230°C. Once the Li droplet was deposited, it began to spread across the sample surface due to the lithiophilic action of the Zn layer. Each sample was left in contact with the molten Li droplet for a specific time interval (four times of 10, 30, 60, and 120 seconds were tested), and then the sample was allowed to cool to room temperature.

[0046] Figure 3 shows the appearance of the copper foil on the back side of each sample. As can be seen, the Cu-Ni-Zn samples show no signs of being affected by contact with molten Li, regardless of the contact time. However, in the case of the Cu-Zn samples, even after 10 seconds of contact with molten Li, there are visible signs of a darker area appearing in the same area where the Li was applied. After 30 seconds of contact, the area corresponding to the Li application shows a light gray area on the back side in the case of Cu-Zn. Figure 4 shows a SEM image and an EDS analysis of the back side of the Cu-Zn sample after 30 seconds of contact with Li. It can be seen that most of the Cu is attacked and that the Cu is left only as small clumps rather than as an intact foil.The effect of the interaction with molten lithium becomes even more significant after 60 and 120 seconds for the Cu-Zn-Li samples, as can be seen in Figure 3. As seen in Figure 3 and Figure 4, the deposition of the Ni layer on the Cu foils effectively protects the Cu foil against its interaction with the molten Li. Example 2

[0047] To evaluate the effect of the Zn layer thickness on its lithophilic property, five 5 µm (14 cm²) square samples of Cu sheets were used. 2The substrates were electroplated with 300 nm of Ni followed by a Zn layer with a thickness of 40, 60, 80, 100, or 150 nm. The same setup described in Example 1 was used to deposit controlled droplets of molten Li (0.1 g) and measure the droplet contact angle as a function of time. Figure 5 shows the variation of the molten Li contact angle on Cu-Ni and Cu-Ni-Zn substrates with different Zn layer thicknesses.

[0048] As can be seen in Figure 5, when the Cu foil is coated only with a 300 nm protective layer of electrodeposited Ni, the surface exhibits no lithiophilia towards Li, with a measured contact angle of approximately 118° after 2 seconds. The contact angle remained practically unchanged, reaching 112° after 120 seconds. In contrast, electrodeposition of only 40 nm of Zn on the Cu-Ni surface resulted in a much lower contact angle of 61° after 30 seconds, demonstrating the lithiophilic effect of the Zn deposition. It can also be seen that increasing the thickness of the Zn deposit leads to an even lower contact angle. To better illustrate the effect of Zn thickness on the lithiophilic effect, the same data from Figure 5 are presented in Figure 6 for contact angle times of 10 and 30 seconds on different Cu-Ni-Zn samples.As can be seen, contact angle values ​​as low as 18° are obtained after 30 seconds of contact between molten Li and Cu-Ni-Zn having a Zn layer 150 nm thick. Example 3

[0049] To evaluate the lithiophilic effect of Sn, three 5 µm (14 cm²) square samples of Cu sheets were used. 2The samples were electroplated with 300 nm of Ni followed by a Sn layer of 40, 60, or 80 nm thickness. The same setup described in Example 1 was used to deposit controlled droplets of molten Li (0.1 g) and measure the droplet contact angle over time. Figure 7 shows the variation of the molten Li contact angle on Cu-Ni and Cu-Ni-Sn substrates with different Sn layer thicknesses. As with Zn, the Cu-Ni-Sn samples also exhibited a very good lithiophilic effect compared to Cu-Ni without a lithiophilic agent on the surface. In the case of Sn, the three samples of 40, 60, and 80 nm thicknesses showed similar lithiophilic activities, as can be seen in Figure 7. Example 4

[0050] To evaluate the lithiophilic effect of ZnO, a Cu-Ni-ZnO sample was prepared by electrodeposition of a thin layer of ZnO onto Cu sheets (14 cm 2) having a 300 nm electrodeposited Ni protective layer. The ZnO layer was electrodeposited using a Cu-Ni foil as the cathode in an electrolysis cell containing a 0.1 M Zn(NO3)2 solution as the electrolyte and a Zn plate as the anode. Electrolysis was carried out at a current density of 5 mA / cm² 2 and at a temperature of 62°C for 36 seconds. The thickness of the ZnO layer is estimated at approximately 30 nm. The sample was then placed in a A glove box similar to the one described in Example 1 was heated to 250°C on a hot plate. Li was then melted onto the sample surface by placing a Li rod made of extruded Li on it. Once the Li had melted, the excess was removed using a high-temperature silicon hand blade. Figure 8 shows a photograph of the surface of the Cu foil sample after Ni electrodeposition (a), ZnO electrodeposition (b), and Li application (c). As can be seen, the molten Li adheres only to the area covered by the electrodeposited ZnO, demonstrating the effectiveness of ZnO as a lithophile material for molten Li application. Example 5

[0051] To evaluate the lithiophilic effect of Sn using a Li alloy, the same type of experiment mentioned in Example 3 was performed using Cu-Ni-Sn (40 nm) and a Li-Mg alloy with a Li:Mg weight ratio of 90%-10%. The variation in the contact angle for Cu-Ni and Cu-Ni-Sn (40 nm) with molten Li and that of Cu-Ni-Sn (40 nm) with the Li-Mg alloy is shown in Figure 9. As can be seen, although the contact angle values ​​of Li-Mg (10%) on Sn (40 nm) are lower than those of Li on Sn (40 nm), Sn (40 nm) still shows clear lithiophilic activity towards Li-Mg (10%) when its contact angle values ​​are compared to those of Li on Cu-Ni without a lithiophilic Sn layer. Example 6

[0052] This example demonstrates the feasibility of using a readily scalable process to apply a thin, uniform layer of lithium to a current collector, such as a 5 µm copper foil, using molten lithium. A sample of 5 µm (130 cm²) copper foils is shown. 2The sample was electroplated with 300 nm of Ni followed by a 40 nm layer of Sn. It was then manually applied at a constant speed of 2 cm / s to the top surface of an anilox cylinder partially immersed in a tank containing molten Li at 260°C. The anilox cylinder was 700 mm long and 19 mm in diameter. It exhibited inverted pyramidal characteristics (20 pyramids by 25 mm) and a depth of approximately 400 pm in each pyramid. A SEM image of the sample (after cryofracture) is shown in Figure 10. A thin Li layer 5 pm thick with good uniformity (variation less than ±1 pm) was obtained. Example 7

[0053] To demonstrate the feasibility of depositing a surface treatment layer on the deposited Li layer of the proposed Li anode material, a Cu-Ni-Sn-Li sample similar to that produced in Example 6 was treated by DC sputtering. A target average value of 50 nm of Zn was deposited by applying a 50 mA DC current to a 99.9% pure Zn target under a 0.008 mbar vacuum and using pure Artrès (grade 6.0; 99.9999% purity). Figure 11 shows the EDS analysis of the sample cross-section.EDS linear scanning analysis through the cross-section as a function of depth shows the copper current collector foil (the total thickness of 5 pm is not shown), the Ni protective layer between 3.5 and 4.0 pm, the Li layer between 0.5 and 3.5 pm (the Li signal is absent in this EDS due to the very weak Li signal itself) and the presence of a Zn layer above the Li layer. Example 8

[0054] Two square samples of Cu foils measuring 5 µm (14 cm²) 2 The elements were electroplated with 300 nm of smooth Ni, followed by the electrodeposition of a rough Ni layer with a 3D effect. Unlike the smooth Ni layer, the 3D layer was electrodeposited at a high current density of 2000 mA / cm². 2 and a total load of 15 C / cm 2using a NiSO4,NH4Cl solution as the electrolyte. One of the samples containing Ni3D was then treated with a non-thermal atmospheric pressure plasma using a Plasma Etch portable plasma wand. The device had a power output of 18 W, and the sample was treated using the near-field module (for electrically conductive materials) at a distance of 2 mm and a speed of approximately 10 mm / s. The same setup described in Example 1 was used to deposit controlled droplets of molten Li (0.1 g) onto Cu-Ni and Cu-Ni-3DNi, both with and without plasma treatment. Due to the roughness of the Cu-Ni-3DNi samples and the rapid propagation of the molten Li droplet, it was difficult to compare the lithiophilic activity using the contact angle parameter.In this case, the molten Li droplet was allowed to spread across the surface for two minutes, and the total surface area of ​​the spread Li was measured and used as an indicator of the substrate surface's lithiophilic activity. The results are shown in Figure 12. As can be seen, electrodeposition of rough 3D Ni onto the substrate leads to an increase in surface lithiophilicity compared to a Cu foil coated only with the smooth Ni layer. Plasma treatment further increased the lithiophilicity of the 3D Ni substrate.

[0055] As a person skilled in the art will understand, the method according to the invention comprises the following steps: a) providing a current collector; b) depositing a layer of protective material on the surface of the current collector; c) depositing a layer of lithiophilic material on the protective material layer; d) and depositing a layer of molten lithium material on the lithiophilic material layer, the lithiophilic material reacting with the molten lithium material to form the anode active material. In embodiments of the invention, the method includes a subsequent step e) depositing a layer of a surface treatment agent on the formed anode active material. In embodiments of the invention, a step a1) forming a continuous 3D structure on a surface of the current collector to obtain a textured current collector is performed before proceeding to step b).

[0056] In some embodiments of the invention, step c) is followed by step c1), which is a plasma treatment of the lithiophilic material to obtain a plasma-treated lithiophilic material. Then step d) is performed. In other embodiments of the invention, step c) is replaced by step c1). In such embodiments of the invention, the plasma treatment is performed on the protective layer, leading to the formation of a lithiophilic surface; advantageously, the protective layer comprises a continuous 3D structure and / or comprises Ni. The plasma treatment may be atmospheric pressure thermal plasma or any other suitable plasma treatment.

[0057] In embodiments of the invention, a continuous 3D structure can be formed on a surface of the anode active material layer and / or a surface of the surface treatment agent layer. A step d1) the formation of a continuous 3D structure on a surface of the anode active material layer is therefore carried out after step d); and / or a step e1) the formation of a continuous 3D structure on a surface of the surface treatment agent layer is carried out after step e).

[0058] The step of forming a continuous 3D structure on a current collector surface to obtain a textured current collector, or on any other surface of any anode layer, may include providing a certain roughness to the current collector surface. This step may include mechanical and / or laser treatment, electrochemical oxidation, chemical etching, or any other suitable technique known to those skilled in the art. In embodiments of the invention, the continuous 3D structure may be imparted to the anode active material layer and / or the surface treatment agent layer.

[0059] The step of depositing a layer of protective material on the surface of the current collector, step b), may include electrochemical deposition, autocatalytic plating, or any suitable technique known to the person skilled in the art.

[0060] The step of depositing a layer of lithiophilic material onto the layer of protective material, step c), may include electrochemical oxidation or reduction, or any suitable technique known to the person skilled in the art.

[0061] The step of depositing a layer of molten lithium material onto the lithiophilic material layer or onto the lithiophilic surface, step d), may include infiltration processes, wave brazing, the use of heated nozzles, the use of anilox cylinders, or any suitable technique.

[0062] As a person skilled in the art will understand, the invention also provides an anode produced by the process according to the invention. The anode can be single-sided or double-sided. Furthermore, the anode can have a thickness of between approximately 4 and approximately 5 µm.

[0063] As a person skilled in the art will understand, the invention further provides a suitable apparatus for carrying out the process according to the invention that produces the anode. The use of the anode in the manufacture of a lithium battery, as well as the manufacturing process for producing a lithium battery including the use of the anode, are also within the scope of the invention. In addition, the invention provides a lithium battery including the anode. The lithium battery can be a lithium-ion battery or an all-solid-state battery.

[0064] As a person skilled in the art will understand, other variations and combinations can be made to the various embodiments of the invention as described above.

[0065] The scope of the claims should not be limited by the preferred embodiments presented in the examples; but should receive the broadest interpretation compatible with the description as a whole.

[0066] The description refers to a number of documents. The content of each of these documents is incorporated here in its entirety by reference.

Claims

DEMANDS 1. A method for producing an anode for a lithium battery, comprising: a) providing a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c) depositing a layer of lithiophilic material on a surface of the protected current collector; and d) depositing a layer of molten lithium material on the lithiophilic material layer, the lithiophilic material reacting with the molten lithium material to form an active anode material layer.

2. A method for producing an anode for a lithium battery, comprising: a) providing a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c) depositing a layer of lithiophilic material on a surface of the protected current collector, then c1) subjecting the layer of lithiophilic material to plasma treatment to obtain a plasma-treated lithiophilic material layer; and d) depositing a layer of molten lithium material on the plasma-treated lithiophilic material layer, the lithiophilic material reacting with the molten lithium material to form an active anode material layer.

3. A method for producing an anode for a lithium battery, comprising: a) supplying a current collector; b) depositing a layer of protective material on a surface of the current collector to obtain a protected current collector; c1) subjecting the protected current collector to plasma treatment to obtain a plasma-treated protected current collector having a lithiophilic surface; and d) depositing a layer of molten lithium material on the lithiophilic surface, thereby forming an active anode material layer.

4. A method according to any one of claims 1 to 3, further comprising a step a1) the formation of a continuous 3D structure on a surface of the current collector to obtain a textured current collector before carrying out step b).

5. A method according to any one of claims 1 to 4, further comprising a step b1) the formation of a continuous 3D structure on a surface of the protected current collector to obtain a textured protected current collector before carrying out step c) or c1).

6. A method according to any one of claims 1 to 5, further comprising (e) the deposition of a layer of a surface treatment agent on the layer of anode active material formed.

7. A method according to any one of claims 1 to 6, further comprising a step d1) the formation of a continuous 3D structure on a surface of the anode material layer before carrying out step e).

8. A method according to any one of claims 1 to 7, further comprising a step e1) the formation of a continuous 3D structure on a surface of the surface treatment agent layer.

9. A method according to any one of claims 1 to 8, wherein steps a1), b), b1), c), c1), d), d1), e), and e1) are carried out on both sides of the current collector and a double-sided anode is produced, optionally steps a1), b), b1), c), c1), d), d1), e), and e1) are all carried out on one side of the current collector and then on the other side of the current collector; optionally each of steps a1), b), b1), c), c1), d), d1), e), and e1) is carried out simultaneously on one side of the collector and then on the other side of the current collector.

10. A method according to any one of claims 1 to 9, wherein steps a1) and b1) each independently comprise an electrochemical deposition of a conductive material on the surface of the current collector or on the surface of the protected current collector, optionally the conductive material is the same material as the current collector; possibly the conductive material is a different material from the current collector.

11. A method according to any one of claims 1 to 10, wherein steps a1) and b1) each independently comprise providing a certain roughness on the surface of the current collector, optionally steps a1) and b1) each independently comprise mechanical and / or laser treatment, electrochemical oxidation, chemical etching, or any suitable technique.

12. A method according to any one of claims 1 to 11, wherein step b) comprises electrochemical deposition, autocatalytic plating, or any suitable technique.

13. A process according to any one of claims 1 to 12, wherein step c) comprises electrochemical oxidation or reduction, or any suitable technique.

14. A method according to any one of claims 1 to 13, wherein the plasma treatment in step c1) is an atmospheric pressure thermal plasma.

15. A method according to any one of claims 1 to 14, wherein step d) comprises infiltration methods, wave welding, the use of heated nozzles, the use of anilox cylinders, or any suitable technique.

16. A method according to any one of claims 1 to 15, wherein at least one drying step is carried out after any one of steps a1), b), b1), c), d), and e).

17. A method according to any one of claims 1 to 16, wherein the lithium material in molten form is at a temperature between about 180°C and about 400°C, optionally the lithium material in molten form is at a temperature of about 210°C. 22 18. A method according to any one of claims 1 to 17, wherein the current collector comprises a material that is Cu, Al, Ni, Ti, C, stainless steel, a conductive polymer, or a combination thereof, optionally the current collector comprises Cu, Al, or carbon-coated aluminum.

19. A method according to any one of claims 1 to 18, wherein the protective material comprises Ni, Co, Cr, Fe, Ti, or a combination thereof, optionally the protective material comprises Ni.

20. A method according to any one of claims 1 to 19, wherein the lithiophilic material comprises CuO, Cu2O, ZnO, MnO2, SnO2, Cu, Au, Mg, Al, In, B, Zn, Sn, Si, SiO2, SiO2 x , a metallic fluoride, a metallic boride, or a combination thereof, possibly the lithiophilic material includes ZnO, Zn, or Sn.

21. A method according to any one of claims 1 to 20, wherein the lithiophilic surface has a continuous 3D structure, optionally the lithiophilic surface comprises Ni.

22. A method according to any one of claims 1 to 21, wherein the molten lithium material comprises lithium or an alloy thereof, optionally the molten lithium material is lithium metal; optionally the lithium alloy is a binary alloy such as Li-Mg, Li-Al, Li-Na, Li-Si, Li-Sn, Li-Zn, Li-Ag, Li-K, Li-B, or any other suitable binary lithium alloy; or the lithium alloy is a ternary alloy such as Li-Al-Na, Li-Mg-Na, Li-Al-Si, Li-Mg-Si, or a ternary alloy comprising elements such as Cu, Zn, Sn, Ca, Sr, or any other suitable ternary lithium alloy.

23. A method according to any one of claims 1 to 16, wherein the surface treatment agent comprises Ag, Zn, SiO₂ x, Sn, Si, l_i2CO3, LiF, carbon black, carbon nanofibre, graphene, or any other suitable surface treatment agent.

24. A method according to any one of claims 1 to 23, wherein the lithium battery is a lithium-ion battery or an all-solid-state battery. 23 25. Anode produced by the process as defined in any one of claims 1 to 24.

26. Anode for a lithium battery, comprising: a current collector; a layer of protective material deposited on the current collector; and an active anode material which is formed as a result of a reaction between a lithiophilic material and a lithium material in molten form, optionally the active anode material is formed as a result of the deposition of the lithium material on a lithiophilic surface.

27. Anode according to claim 25 or 26, wherein there is substantially no physical or chemical interaction between the current collector and the anode active material.

28. Anode according to any one of claims 25 to 27, which is single-sided or double-sided.

29. Anode according to any one of claims 25 to 28, wherein the current collector has a thickness of between about 4 and about 5 pm.

30. Apparatus adapted to produce the anode as defined in any one of claims 25 to 29.

31. Use of the anode as defined in any one of claims 25 to 29, in the manufacture of a lithium battery.

32. Method of manufacturing a lithium battery, comprising the use of the anode as defined in any one of claims 25 to 29.

33. Lithium battery comprising the anode as defined in any one of claims 25 to 29, optionally the lithium battery is a lithium-ion battery or an all-solid-state battery.

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