Surface modification of current collectors prior to coating with molten metal

Abstract

The invention relates to surface modification of current collectors prior to coating with molten metal. A method of manufacturing an anode electrode for a battery cell includes: providing a current collector; and forming a layer on the current collector to produce a coated current collector. The layer includes one of a metal and a metal oxide that are immiscible in molten lithium. The method includes immersing the coated current collector in molten lithium to coat the coated current collector.

Description

Technical Field

[0001] The present disclosure relates to current collectors for electrodes of battery cells, and more particularly to methods of coating the current collectors of battery cells with metals or metal oxides prior to immersion in molten lithium metal. Background Art

[0002] The information provided in this section is for the purpose of generally introducing the background of the present disclosure. No admission is made, either explicitly or implicitly, that the work of the presently named inventors described in this section is prior art to the present disclosure, nor is it admitted that the work is prior art to the present disclosure, as described in this section, which may not otherwise be identified as prior art at the time of filing.

[0003] Electric vehicles (EVs), such as battery electric vehicles (BEVs), hybrid electric vehicles, and / or fuel cell vehicles, include one or more motors and a battery system, which includes one or more battery cells, modules, and / or packs. A battery control module is used to control the charging and / or discharging of the battery system during charging and / or driving. EV manufacturers are committed to improving power density to increase the range of EVs. Summary of the invention

[0004] A method of making an anode electrode for a battery cell includes: providing a current collector; and forming a layer on the current collector to produce a coated current collector. The layer includes one of a metal and a metal oxide, the metal and the metal oxide being immiscible in molten lithium. The method includes immersing the coated current collector in molten lithium to coat the coated current collector.

[0005] In other features, the current collector includes a mesh current collector. The current collector is made of a material selected from copper (Cu), stainless steel (SS), nickel (Ni), and alloys thereof. The current collector includes a plurality of first wires and a plurality of second wires, and the plurality of second wires are superimposed relative to the plurality of first wires and arranged at a certain angle. The plurality of first wires and the plurality of second wires have a thickness of 4 μm to 100 μm. The current collector includes 100 to 300 openings / square inch between the plurality of first wires and the plurality of second wires. One of the metals and metal oxides is selected from zinc (Zn), nickel (Ni), bismuth (Bi), tin (Sn) and germanium (Ge). One of the metals and metal oxides is selected from zinc (Zn) oxide, nickel (Ni) oxide, bismuth (Bi) oxide, tin (Sn) oxide and germanium (Ge) oxide.

[0006] In other features, the layer is electrochemically deposited on the current collector. The layer is vacuum deposited on the current collector. The layer is sputtered onto the current collector. The layer is laser deposited onto the current collector. The layer has a thickness of 5 nm to 200 nm.

[0007] A method for manufacturing an anode electrode includes: providing a mesh current collector, the mesh current collector is made of a material selected from copper, stainless steel and nickel; and forming a layer on the mesh current collector to produce a coated mesh current collector. The layer comprises one of a metal and a metal oxide, the metal and the metal oxide are selected from nickel (Ni), zinc (Zn), bismuth (Bi), tin (Sn), germanium (Ge), and oxides thereof, and the layer has a thickness of 5nm to 200nm. The method includes immersing the coated mesh current collector in molten lithium to coat the coated mesh current collector.

[0008] In other features, the mesh current collector includes a plurality of first wires and a plurality of second wires arranged at a certain angle relative to the plurality of first wires. The plurality of first wires and the plurality of second wires have a thickness of 4 μm to 100 μm. The mesh current collector includes 100 to 300 openings per square inch between the plurality of first wires and the plurality of second wires.

[0009] In other features, one of the layers is electrochemically deposited on the mesh current collector, the layer is vacuum deposited on the mesh current collector, the layer is sputtered onto the mesh current collector, and the layer is laser deposited on the mesh current collector.

[0010] The anode electrode for a battery cell includes a mesh current collector made of a material selected from copper, stainless steel and nickel. A layer is arranged on the mesh current collector. The layer includes one of a metal and a metal oxide selected from nickel (Ni), zinc (Zn), bismuth (Bi), tin (Sn), germanium (Ge), and oxides thereof, and the layer has a thickness of 5 nm to 200 nm. A lithium layer formed from molten lithium coats the layer.

[0011] The present invention discloses the following scheme:

[0012] Solution 1. A method for manufacturing an anode electrode for a battery cell, the method comprising:

[0013] providing a current collector;

[0014] forming a layer on a current collector to produce a coated current collector,

[0015] wherein the layer comprises one of a metal and a metal oxide, the metal and the metal oxide being immiscible in molten lithium; and

[0016] The coated current collector is immersed in molten lithium to coat the coated current collector.

[0017] Option 2. A method according to Option 1, wherein the current collector comprises a mesh current collector.

[0018] Option 3. The method according to Option 1, wherein the current collector is made of a material selected from the group consisting of copper (Cu), stainless steel (SS), nickel (Ni), and alloys thereof.

[0019] Option 4. The method according to Option 2, wherein the current collector comprises a plurality of first wires and a plurality of second wires, and the plurality of second wires are stacked relative to the plurality of first wires and arranged at a certain angle.

[0020] Aspect 5. The method according to aspect 4, wherein the plurality of first wires and the plurality of second wires have a thickness of 4 μm to 100 μm.

[0021] Option 6. The method according to Option 2, wherein the current collector comprises 100 to 300 openings per square inch between the plurality of first wires and the plurality of second wires.

[0022] Option 7. The method according to Option 1, wherein one of the metal and the metal oxide is selected from zinc (Zn), nickel (Ni), bismuth (Bi), tin (Sn) and germanium (Ge).

[0023] Option 8. A method according to Option 1, wherein one of the metal and the metal oxide is selected from zinc (Zn) oxide, nickel (Ni) oxide, bismuth (Bi) oxide, tin (Sn) oxide and germanium (Ge) oxide.

[0024] Option 9. A method according to Option 1, wherein the layer is electrochemically deposited on the current collector.

[0025] Option 10. The method according to Option 1, wherein the layer is vacuum deposited on the current collector.

[0026] Option 11. A method according to Option 1, wherein the layer is sputtered onto the current collector.

[0027] Option 12. A method according to Option 1, wherein the layer is laser deposited onto the current collector.

[0028] Embodiment 13. The method according to embodiment 1, wherein the layer has a thickness of 5 nm to 200 nm.

[0029] Solution 14. A method for manufacturing an anode electrode, the method comprising:

[0030] providing a mesh current collector made of a material selected from the group consisting of copper, stainless steel and nickel;

[0031] forming a layer on the mesh current collector to produce a coated mesh current collector,

[0032] wherein the layer comprises one of a metal and a metal oxide selected from nickel (Ni), zinc (Zn), bismuth (Bi), tin (Sn), germanium (Ge), and oxides thereof, and the layer has a thickness of 5 nm to 200 nm; and

[0033] The coated mesh current collector is immersed in molten lithium to coat the coated mesh current collector.

[0034] Option 15. The method according to Option 14, wherein the mesh current collector comprises a plurality of first wires and a plurality of second wires arranged at a certain angle relative to the plurality of first wires.

[0035] Aspect 16. The method according to aspect 15, wherein the plurality of first wires and the plurality of second wires have a thickness of 4 μm to 100 μm.

[0036] Embodiment 17. The method according to embodiment 15, wherein the mesh current collector comprises 100 to 300 openings per square inch between the plurality of first wires and the plurality of second wires.

[0037] Embodiment 18. The method according to embodiment 14, wherein one of the following:

[0038] The layer is electrochemically deposited on the mesh current collector,

[0039] The layer is vacuum deposited on the mesh current collector,

[0040] The layer is sputtered onto the mesh current collector, and

[0041] The layer is laser deposited on the mesh current collector.

[0042] Embodiment 19. An anode electrode for a battery cell, comprising:

[0043] a mesh current collector made of a material selected from copper, stainless steel and nickel;

[0044] a layer disposed on the mesh current collector,

[0045] wherein the layer comprises one of a metal and a metal oxide selected from nickel (Ni), zinc (Zn), bismuth (Bi), tin (Sn), germanium (Ge), and oxides thereof, and the layer has a thickness of 5 nm to 200 nm; and

[0046] A lithium layer formed from molten lithium coats the layer.

[0047] Further areas of applicability of the present disclosure will become apparent from the detailed description, claims and drawings.The detailed description and specific examples are intended for illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present disclosure will be more fully understood from the detailed description and the accompanying drawings, in which:

[0049] Figure 1 is a cross-sectional view of an example of a battery cell including an anode electrode, a cathode electrode, and a separator according to the present disclosure;

[0050] Figure 2A and 2B is a plan view showing an example of a copper current collector after being immersed in molten lithium;

[0051] Figure 2C is a plan view showing an example of a coated copper current collector after immersion in molten lithium according to the present disclosure;

[0052] Figure 3 is an example of a binary phase diagram for lithium and copper;

[0053] Figure 4A and 4B shows an example of intergranular etching during immersion of a copper current collector in molten lithium;

[0054] Figure 5 and 6 is an enlarged view showing an example of a grain boundary of copper dissolved in molten lithium when an uncoated current collector is used;

[0055] Fig. 7A An example of electrochemical coating of a current collector having a metal or metal oxide layer that is immiscible in molten lithium according to the present disclosure is shown;

[0056] Figure 7B An example of a coated mesh current collector according to the present disclosure being immersed in molten lithium to form a lithium anode electrode is shown;

[0057] Figure 8 is an example of a method according to the present disclosure for making a coated mesh current collector that is immersed in molten lithium to form a lithium anode electrode for a battery cell; and

[0058] Fig. 9 An example of a coated mesh current collector after immersion in molten lithium according to the present disclosure is shown;

[0059] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0060] Although battery cells and / or electrodes according to the present disclosure are described herein in the context of electric vehicles, the battery cells and / or electrodes may be used in stationary applications and / or other types of applications.

[0061] The battery cell includes an anode electrode, a cathode electrode and a separator arranged in a predetermined order in a housing. The anode electrode includes an anode active layer arranged on one or both sides of an anode current collector. The cathode electrode includes a cathode active layer arranged on one or both sides of a cathode current collector.

[0062] In some embodiments, the anode current collector and the cathode current collector include a wire mesh, a foil, or a porous metal sheet (expanded metal). For example, the mesh current collector includes superimposed wires arranged at a certain angle and made of copper, stainless steel, nickel, and alloys thereof. The wire mesh current collector can be made of wires with a thickness of 4 μm to 100 μm (e.g., 30 μm). In some embodiments, the wire mesh current collector has about 100 to 300 openings per square inch (e.g., 100).

[0063] The present disclosure relates to a method for coating a current collector (e.g., a copper mesh current collector) with lithium molten metal (e.g., lithium or a lithium alloy). For example, when a copper-based mesh current collector is immersed in molten lithium, some of the copper in the copper mesh current collector dissolves in the molten lithium due to a dissolution-assisted (intergranular) corrosion reaction between the molten lithium and the copper. This dissolution causes decomposition of part of the wire of the mesh current collector. In addition, the molten lithium bath is contaminated by the dissolved copper, which adversely affects the density of the lithium anode electrode prepared using the contaminated molten lithium bath.

[0064] Before the current collector is immersed in a molten lithium bath, the current collector is coated with a metal or metal oxide that is not miscible with the molten lithium. For example, the metal or metal oxide layer may include a material selected from tin (Sn), zinc (Zn), nickel (Ni), bismuth (Bi), germanium (Ge), and oxides thereof. The metal or metal oxide layer prevents intergranular corrosion of the base metal (e.g., copper) of the current collector.

[0065] Reference now Figure 1, the battery cell 10 includes cathode electrodes 20-1, 20-2, ... and 20-C, where C is an integer greater than 1. The cathode electrode 20 includes a cathode active material layer 24 arranged on one side or both sides of a cathode current collector 26. The battery cell 10 includes anode electrodes 40-1, 40-2, ... and 40-A, where A is an integer greater than 1. The anode electrode 40 includes an anode active material layer 42 arranged on one side or both sides of an anode current collector 46. The cathode electrode 20, the anode electrode 40 and the separator 32 are arranged in a predetermined order in the housing 50. For example, the separator 32 is arranged between the cathode electrode 20 and the anode electrode 40.

[0066] Reference now Figures 2A to 2C , shows an example of dissolution of a base metal of a current collector when immersed in lithium metal. In this example, the current collector comprises a copper current collector 80 comprising a wire mesh. Figure 2A and 2B In the embodiment, the copper current collector 80 is uncoated before being immersed in molten lithium. Figure 2B As can be seen in FIG. 8 , limited lithium wetting of the copper current collector 80 occurs at 84 , and the copper of the copper mesh dissolves in the molten lithium due to a dissolution-assisted (intergranular) corrosion reaction between the molten lithium and the copper.

[0067] exist Figure 2C In the embodiment, the current collector 90 comprises a copper wire mesh including an outer layer 91 disposed on the current collector. The outer layer 91 comprises a metal or metal oxide species that does not have miscibility in molten lithium. Miscibility is the property of two substances to mix and form a homogeneous mixture.

[0068] For example, the outer layer 91 may include a material selected from tin (Sn), zinc (Zn), nickel (Ni), bismuth (Bi), germanium (Ge), and oxides thereof. The outer layer 91 may be applied using any suitable process, such as electrochemical deposition, vacuum deposition, sputtering, laser deposition, or other methods. When the current collector 90 having the outer layer 91 is immersed in molten lithium 92, the molten lithium 92 does not dissolve the base metal of the current collector. The molten lithium 92 can penetrate into the gaps between the wires of the current collector 90 and improve the wetting of the current collector 90.

[0069] Reference now Figure 3, the figure shows a binary phase of lithium and copper. The liquid phase of lithium is shown at 210, the liquid and solid copper phases are shown at 220, the solid lithium and copper phases are shown at 230, and the solid copper phase is shown at 240. The Li-Cu binary phase diagram shows the limited (near zero) mutual solubility between Li and Cu. Note that there is no intermetallic phase in the Li-Cu system. When liquid lithium comes into contact with copper, a two-phase equilibrium is established, and a portion of the copper is replaced by a lithium-rich liquid. Since liquid Li does not have an intermetallic reaction with Cu, the Li-rich liquid directly enters the grain boundaries in the Cu substrate, which provides a path for intergranular etching. On the other hand, liquid tin (Sn) behaves differently because it will dissolve Cu and form an intermetallic phase between the two elements.

[0070] Reference now Figure 4A and 4B , showing a dissolution-assisted (intergranular) corrosion reaction. Figure 4A In FIG. 3 , copper 310 (eg, the base metal of the current collector in some embodiments) includes grain boundaries 314 and 322. Figure 4B In the embodiment of the present invention, intergranular corrosion occurs when copper 310 is immersed in molten lithium 320. Molten lithium 320 penetrates grain boundaries 322 and eventually causes partial dissolution of copper 310.

[0071] Reference now Figure 5 and 6 , molten lithium enters the grain boundaries and dissolves some copper. The molten lithium-copper alloy solidifies at the grain boundaries, which weakens the grain boundaries. Some Cu grains have weakened intergranular connections and separate from the rest of the Cu substrate (e.g., copper mesh), resulting in decrepitation of Cu. The copper dissolved in the molten Li will precipitate out during solidification, resulting in lithium contamination. Figure 5 and 6 The precipitation of copper into molten lithium is shown.

[0072] In order to eliminate the dissolution of the base metal (e.g., Cu) of the current collector when immersed in molten lithium, an outer layer of a metal or metal oxide is coated on the current collector. The metal or metal oxide species does not have miscibility in molten lithium. For example, the layer may include tin (Sn), zinc (Zn), nickel (Ni), bismuth (Bi), germanium (Ge), and oxides thereof.

[0073] The outer layer may be applied to the current collector using any suitable process (e.g., electrochemical deposition, vacuum deposition, sputtering, laser deposition, or other deposition methods) (before immersion in molten lithium). In some embodiments, the metal or metal oxide layer is deposited on the current collector using electron beam evaporation and / or vacuum thermal evaporation. In some embodiments, the metal or metal oxide layer is deposited on the current collector using chemical vapor deposition (CVD) and / or physical vapor deposition (PVD). In some embodiments, the metal or metal oxide layer is deposited on the current collector using atomic layer deposition (ALD), molecular beam epitaxy (MBE), and / or arc evaporation. In some embodiments, the metal or metal oxide layer is deposited on the current collector using a sputtering method (e.g., DC and RF sputtering, DC magnetron sputtering, and / or reactive sputtering). In some embodiments, the metal and / or metal oxide layer is deposited on the current collector using laser deposition techniques such as pulsed laser deposition.

[0074] Reference now Fig. 7A and 7B , shows an example of making a current collector using electrochemical deposition. First, an electrodeposition of a metal or metal oxide layer is performed on the current collector in a bath. Subsequently, the current collector with the metal or metal oxide layer is immersed in molten lithium in another bath.

[0075] exist Fig. 7A In the embodiment of the present invention, the negative terminal of the power supply 522 is connected to the current collector 520 (e.g., a copper mesh current collector) and immersed in a bath 510 containing a molten metal salt or a molten metal oxide salt 514. The positive terminal of the power supply 522 is connected to the bath 510 (or the molten metal salt or the molten metal oxide salt 514). The power supply 522 generates a voltage difference, which causes the metal or metal oxide to be electrodeposited on the outer surface of the current collector 520 and produces a layer. When the layer has a sufficient thickness (usually proportional to the plating time), the current collector 520 (and including the metal layer or metal oxide layer) is removed from the bath 510. In some embodiments, the metal layer or metal oxide layer has a thickness of 5nm to 200nm, although other thicknesses can be used. In some embodiments, the current collector is coated for a time of 15 seconds to 2 minutes, although other coating times can be used.

[0076] exist Figure 7B In the embodiment of the present invention, after the deposition of the layers, the current collector 520 having the metal layer or the metal oxide layer is immersed in a bath 530 containing molten lithium 534. The molten lithium 534 coats the current collector 520 without dissolving the base metal (eg, Cu) of the current collector 520.

[0077] exist Figure 8, a method 600 for making a coated mesh current collector, a lithium anode electrode, and / or a battery cell is shown. At 610, a current collector is provided. At 614, a layer of a metal or metal oxide is deposited on the current collector 614 using any suitable method (e.g., electrochemical deposition or other methods). Once the layer is applied to the current collector, the current collector is immersed in molten lithium at 620 to produce a lithium anode electrode. At 624, the lithium coated anode is arranged in a battery cell stack.

[0078] exist Fig. 9 In the figure, a metal layer or metal oxide layer 650 is shown on the outer surface of the base metal of the current collector 640 (e.g., a copper mesh current collector). The metal layer or metal oxide layer 650 acts as a barrier to the molten lithium layer 660 and prevents intergranular corrosion in the grain boundaries 642 and 644. By introducing a metal / metal oxide coating between the lithium and the copper, dissolution in the grain boundaries of the copper current collector is avoided. This allows the energy density of the lithium anode to be unaffected by the copper.

[0079] The foregoing description is exemplary only and is absolutely not intended to limit the present disclosure, its application or use. The broad teachings of the present disclosure can be implemented in various forms. Therefore, although the present disclosure includes specific examples, the true scope of the present disclosure should not be limited thereto, because after studying the drawings, the specification and the following claims, other modifications will become apparent. It should be understood that one or more steps in the method may be implemented in different orders (or simultaneously) without changing the principles of the present disclosure. In addition, although each embodiment is described above as having certain features, any one or more features described with respect to any embodiment of the present disclosure may be implemented in any other embodiment and / or combined with the features of any other embodiment, even if the combination is not explicitly described. In other words, the embodiments are not mutually exclusive, and the mutual replacement of one or more embodiments is still within the scope of the present disclosure.

[0080] Various terms are used to describe the spatial and functional relationships between elements (e.g., between modules, circuit elements, semiconductor layers, etc.), including "connected," "engaged," "coupled," "adjacent," "next to," "on top of," "on," "under," and "disposed." Unless explicitly described as "directly," when describing the relationship between a first element and a second element in the above disclosure, the relationship can be a direct relationship in which there are no other intervening elements between the first element and the second element, or an indirect relationship in which there are one or more intervening elements (spatially or functionally) between the first element and the second element. The phrase "at least one of A, B, and C" as used herein should be interpreted to mean a logical (A or B or C) using a non-exclusive logical OR, and should not be interpreted to mean "at least one of A, at least one of B, and at least one of C."

[0081] In the drawings, the direction of the arrows, as shown by the arrows, generally shows the flow of information (such as data or instructions) that the illustration is concerned with. For example, when component A and component B exchange various information but the information sent from component A to component B is relevant to the illustration, the arrow may point from component A to component B. Such a one-way arrow does not mean that no other information is sent from component B to component A. In addition, for information transmitted from component A to component B, component B may send a request for the information or a receipt to component A.

Claims

1. A method for manufacturing an anode electrode for a battery cell, the method comprising: providing a current collector; forming a layer on a current collector to produce a coated current collector, wherein the layer comprises one of a metal and a metal oxide, the metal and the metal oxide being immiscible in molten lithium; and The coated current collector is immersed in molten lithium to coat the coated current collector. The method according to claim 1 , wherein the current collector comprises a mesh current collector. 3 . The method according to claim 1 , wherein the current collector is made of a material selected from the group consisting of copper (Cu), stainless steel (SS), nickel (Ni), and alloys thereof. 4 . The method according to claim 2 , wherein the current collector comprises a plurality of first wires and a plurality of second wires, the plurality of second wires being overlapped with respect to the plurality of first wires and arranged at a certain angle. 5 . The method according to claim 4 , wherein the plurality of first wires and the plurality of second wires have a thickness of 4 μm to 100 μm. 6 . The method of claim 2 , wherein the current collector comprises 100 to 300 openings per square inch between the plurality of first wires and the plurality of second wires. 7 . The method according to claim 1 , wherein one of the metal and the metal oxide is selected from zinc (Zn), nickel (Ni), bismuth (Bi), tin (Sn), and germanium (Ge).

8. The method according to claim 1, wherein one of the metal and the metal oxide is selected from zinc (Zn) oxide, nickel (Ni) oxide, bismuth (Bi) oxide, tin (Sn) oxide, and germanium (Ge) oxide.

9. The method of claim 1, wherein the layer is electrochemically deposited on the current collector.

10. The method of claim 1, wherein the layer is vacuum deposited onto the current collector.

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