Lithium battery negative electrode, manufacturing method therefor and use thereof

Abstract

A lithium battery negative electrode, a manufacturing method therefor and the use thereof. The lithium battery negative electrode consists of a strip-shaped lithium strip or lithium alloy strip and a current collection part combined with at least one side edge of the strip-shaped lithium strip or lithium alloy strip, wherein the at least one side edge of the lithium strip or lithium alloy strip is provided with a pretreatment area, and the current collection part comprises an area having a stress buffer layer, the pretreatment area and the area having a stress buffer layer being mutually clad with each other.

Description

A lithium battery negative electrode and its preparation method and application Technical Field

[0001] The present invention relates to the technical field of electrochemical energy storage, and in particular to a lithium negative electrode for a metal lithium battery, and a preparation method and application thereof. Background Art

[0002] As society's requirements for the energy density of lithium-ion batteries are getting higher and higher. First of all, we need to use negative electrode materials with higher specific capacity. Metal lithium is considered to be the best negative electrode material due to its capacity of 3860mAh / g and low potential of -3.04V. At present, many battery manufacturers use pure metal lithium strips as negative electrodes for direct use. The thickness of metal lithium is 50-80um. Metal lithium itself is very soft. When the thickness is less than 100um, it is very difficult to produce it in a roll. It is even more difficult to roll out the pole ears of metal lithium strips. Patent CN209641727 discloses that metal lithium is first die-cut into pieces of negative electrode sheets, and then a pressure of 0.3 to 0.5MPa is used to attach the copper pole ears to the single-piece pole sheet to lead out the pole ears. This process is time-consuming and labor-intensive to lead out the pole ears, and cannot be used in large-scale production. In addition, many research institutes use lithium-copper laminated strips as negative electrodes. Since the density of copper is 8.96g / cm 3 , which is 16 times the density of metallic lithium. 6um copper foil is equivalent to 100um thick lithium. The product of using the entire copper foil to cover metallic lithium has limited specific energy, so the existing negative electrode still cannot meet the requirements of high specific energy batteries.

[0003] Summary of the Invention

[0004] The present invention proposes a new type of metallic lithium negative electrode. The bonding area between the tab and the lithium ribbon in this lithium negative electrode is very narrow and accounts for a very small proportion, which greatly improves the specific energy of the battery. In addition, the method of leading out the tab is relatively convenient, and it can be rolled into a large-scale batch production for use.

[0005] Currently, most lithium-copper cladding processes use a pressure cladding process. The inventors of this application have discovered that when copper foil is clad only on the edge of a lithium strip as a tab, because the copper and lithium cladding area is very narrow (3-10mm), the force is only applied to the very narrow cladding area. The pressure during cladding is small, the lithium and copper are not well adhered, and the lithium is easily peeled off from the copper, resulting in poor current collection effect. However, the pressure during cladding is high, and the lithium material in the cladding area will expand accordingly, but the lithium material in other unclad areas will not expand due to the lack of force. During the roll production of lithium metal negative electrode products, the lithium in the cladding area and the lithium in the unclad area are inconsistent in length (this inconsistency becomes more obvious as the length increases), causing the lithium in the unclad area to undergo tensile deformation.

[0006] To address the above problems, the inventors designed a stress buffer layer, which is provided in the area where the tab is to be combined with the lithium ribbon and is composed of raised discontinuous metal particles. These raised particles can be extended and deformed under external force when the tab and the lithium ribbon are laminated (the height of the raised particles becomes smaller), so that the stress generated during the lamination can be buffered and released, reducing or avoiding the extension of the lithium material in the lamination area under stress. In addition, the area where the lithium ribbon is to be combined with the tab can be pretreated to form a pretreated area with a reduced thickness. The pretreated area has a new metal lithium surface (the original lithium surface has a passivation layer, which is not conducive to the lamination of lithium and copper together), which is conducive to better lamination of the stress buffer layer and the lithium ribbon. At the same time, the raised particles in the stress buffer layer can also fill the thinned area after deformation, resulting in a metal lithium negative electrode with a smooth surface and a self-contained tab.

[0007] The technical solutions of the present invention are as follows.

[0008] One aspect of the present invention provides a lithium battery negative electrode, which is composed of a long strip of lithium or lithium alloy strip and a current collecting and gathering portion coupled to at least one side edge of the long strip of lithium or lithium alloy strip, wherein at least one side edge of the lithium or lithium alloy strip has a pretreated area, the current collecting and gathering portion includes an area having a stress buffer layer, and the pretreated area and the area having the stress buffer layer overlap each other.

[0009] According to one embodiment, the current collecting and converging portion further includes a portion that does not overlap with the pre-treated area and extends beyond the width of the lithium ribbon or lithium alloy ribbon, and the portion is die-cut into a tab.

[0010] According to one embodiment, the lithium metal ribbon or lithium alloy ribbon has a thickness of 0.01-0.15 mm and a width of 10-1500 mm. Preferably, the lithium metal ribbon or lithium alloy ribbon has a thickness of 0.01-0.10 mm, more preferably 0.010-0.05 mm; and a width of 20-1500 mm, more preferably 50-1500 mm, such as 150-1500 mm, 200-1500 mm, 250-1500 mm, 300-1500 mm, 350-1500 mm, 400-1500 mm, 450-1500 mm, or 500-1500 mm.

[0011] According to one embodiment, the width of the pre-treated area is 2-10 mm, and the thickness of the pre-treated area is 0.1-5 μm thinner than that of other areas, preferably 1-5 μm; the pre-treatment methods include erasing, rolling, and gluing.

[0012] According to one embodiment, the lithium alloy comprises a binary alloy and / or a multinary alloy, preferably a binary alloy and / or a ternary alloy.

[0013] According to one embodiment, the lithium alloy is formed by a combination of metallic lithium and any one or at least two elements of Ag, Au, Sn, Si, Zn, Al, Mg, In, Ga, B, Mn, Sb, Cr, V, Cu, Fe or Ti, and the mass proportion of metallic lithium in the lithium alloy can be more than 50%, preferably more than 70%, more preferably more than 80%, or even more than 90%.

[0014] According to one embodiment, the current collecting and converging portion is made of a metal foil selected from copper foil, nickel foil, stainless steel foil or a composite metal current collector; the foil thickness is 3-10 um, preferably 3-8 um.

[0015] According to one embodiment, the width of the current collecting and converging portion is 12-30 mm; and the width of the stress buffer layer is 2-10 mm.

[0016] According to one embodiment, the stress buffer layer comprises discontinuous raised metal particles formed by vapor deposition, with a particle size of 1-7 μm, preferably 1-5 μm. The raised height of the metal particles is 1-5 μm, and the area ratio of the metal particles to the stress buffer layer is 1:3 to 9:10.

[0017] According to one embodiment, the metal particles include at least one of tin particles, zinc particles, magnesium particles, aluminum particles, silver particles, and lithium particles.

[0018] According to one embodiment, the type of the metal particles is the same as the alloying element contained in the lithium alloy ribbon.

[0019] According to one embodiment, the type of the metal particles is different from the alloying elements contained in the lithium alloy ribbon.

[0020] According to one embodiment, the pre-treated area and the area of ​​the current collecting and converging portion having the stress buffer layer are laminated together by at least one of diffusion welding, ultrasonic welding, resistance welding, and pressure welding processes; and the width of the laminated area ranges from 2 to 10 mm.

[0021] According to one embodiment, the area where the stress buffer layer and the lithium or lithium alloy ribbon overlap in the current collecting and converging portion can be continuous or discontinuous. Because atoms continuously diffuse, the discontinuous area will eventually diffuse to a uniform state. For example, the stress buffer layer in the current collecting and converging portion can be divided into several discrete sections, each separated by a predetermined distance, for example, 0.1-1 mm. The stress buffer layer can also have a grid pattern.

[0022] According to one embodiment, the thickness of the stress buffer layer and the overlapping region of the lithium ribbon or lithium alloy ribbon in the current collecting and converging portion is equal to or slightly greater than the thickness of the pure lithium ribbon or lithium alloy ribbon. For example, if the lithium ribbon is 50 μm thick, the thickness of the stress buffer layer and the overlapping region of the current collecting and converging portion is 55 μm; if the lithium ribbon is 60 μm thick, the thickness of the stress buffer layer and the overlapping region of the current collecting and converging portion is 60 μm; if the lithium-magnesium alloy ribbon (10% magnesium content) is 60 μm thick, the thickness of the stress buffer layer and the overlapping region of the current collecting and converging portion is 63 μm; if the lithium-silver alloy ribbon (1% silver content) is 40 μm thick, the thickness of the stress buffer layer and the overlapping region of the current collecting and converging portion is 40 μm.

[0023] Another aspect of the present invention provides a method for preparing the above-mentioned lithium battery negative electrode, comprising:

[0024] Step 1: Depositing discontinuous raised metal particles on the metal foil through a vapor deposition process to obtain a current collecting and gathering portion with a stress buffer layer covered in some areas;

[0025] Step 2: Pre-treating at least one edge region of the lithium ribbon or lithium alloy ribbon by at least one of wiping, rolling, and gluing to form a pre-treated region with a width of 2-10 mm;

[0026] Step 3: welding the region of the current collecting and converging portion having the stress buffer layer obtained in Step 1 and the pretreated region of the lithium ribbon or lithium alloy ribbon obtained in Step 2 together by at least one of diffusion welding, ultrasonic welding, resistance welding, and pressure welding, so that the metal particles of the stress buffer layer and the lithium in the lithium ribbon or lithium alloy ribbon are fused together to form a fusion region of lithium and metal particles; and

[0027] Optional step four: die-cutting the portion of the current collecting and converging portion that does not overlap with the pre-treated area and extends beyond the width of the lithium strip or lithium alloy strip to form a tab.

[0028] According to one embodiment, in step one, the conductive foil of the current collecting and gathering part is first subjected to a low-temperature plasma degreasing treatment; the degreased conductive foil is dried, and the dried conductive foil is subjected to a vapor deposition process to deposit discontinuous raised metal lithium particles to obtain a stress buffer layer, and the width of the stress buffer layer is 2-10 mm.

[0029] Another aspect of the present invention provides the use of the high-energy-density lithium battery negative electrode in a lithium-ion battery. The high-energy-density metal lithium negative electrode can be used as the negative electrode of a metal lithium battery.

[0030] According to one embodiment, the present invention provides a lithium battery comprising the above-mentioned lithium battery negative electrode, wherein the positive electrode material is selected from ternary nickel-cobalt-manganese material, ternary nickel-cobalt-aluminum material, lithium-rich manganese-based positive electrode material, lithium cobalt oxide, lithium iron phosphate, and sulfur positive electrode material.

[0031] According to one embodiment, the electrolyte of the lithium battery can be a liquid electrolyte or a solid electrolyte; the liquid electrolyte can be an ester or an ether; the solid electrolyte can be an oxide solid electrolyte, a sulfide solid electrolyte or a polymer electrolyte, such as a PEO (mixed oxide or sulfide powder) electrolyte.

[0032] For liquid batteries, the diaphragm is made of PP, PE or a three-layer laminate of PP and PE, and the diaphragm can be provided with a ceramic coating.

[0033] Batteries can be made into square, soft-pack and cylindrical batteries.

[0034] The present invention has at least one of the following advantages:

[0035] (1) The high-energy-density lithium metal negative electrode of the present invention can be produced in batches in rolls, solving the problem of difficulty in engineering the tabs of pure lithium strip negative electrodes.

[0036] (2) The high specific energy metal lithium negative electrode of the present invention has its own tabs, which can be directly die-cut for use without the need for additional tabs.

[0037] (3) The high-energy-density lithium metal negative electrode of the present invention can be used directly as a negative electrode. Since the current collecting and gathering part has a small area and occupies a small proportion, a battery with an energy density exceeding 500wh / kg can be prepared by using this negative electrode in conjunction with a high-capacity positive electrode material.

[0038] (4) The problem of loose adhesion between lithium and the current collecting part is solved. The stress buffer layer can be in close contact with the lithium strip or lithium alloy strip, and the current collecting effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] FIG1 is a schematic diagram of the planar structure of the negative electrode of a lithium battery of the present invention.

[0040] FIG2 is a cross-sectional view of the negative electrode of a lithium battery according to the present invention, in which the thickness of the lithium and the current collecting portion is greater than the thickness of the lithium strip or lithium alloy strip.

[0041] FIG3 is another cross-sectional view of the negative electrode of the lithium battery of the present invention, in which the thickness of the lithium and the current collecting portion is equal to the thickness of the lithium strip or lithium alloy strip.

[0042] FIG4 is a physical picture of lithium metal particles in the stress buffer layer in Example 2.

[0043] FIG5 is a physical picture of magnesium metal particles in the stress buffer layer in Example 5. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only intended to illustrate the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0045] Furthermore, the various product structural parameters, various reaction participants and process conditions used in the following embodiments are all relatively typical examples. However, after a large number of experiments and verifications by the inventors of this case, other different structural parameters, other types of reaction participants and other process conditions listed above are also applicable and can also achieve the technical effects claimed in the present invention.

[0046] Figure 1 is a schematic diagram (top view) of the planar structure of a lithium battery negative electrode according to the present invention, wherein the lithium battery negative electrode comprises a lithium ribbon or lithium alloy ribbon 1 and a current collecting and converging portion 2 bonded to one edge of the lithium ribbon or lithium alloy ribbon. Figures 2 and 3 show cross-sectional views of the lithium battery negative electrode according to the present invention, wherein the pretreated region of the lithium ribbon or lithium alloy ribbon 1 and the region of the current collecting and converging portion 2 having a stress buffer layer overlap to form a joint 3 (a fusion region of lithium and metal particles). In Figure 2, the thickness of the overlapping region is greater than the thickness of the lithium ribbon or lithium alloy ribbon, while in Figure 3, the thickness of the overlapping region is equal to the thickness of the lithium ribbon or lithium alloy ribbon.

[0047] Example 1:

[0048] The thickness of the rolled copper foil (collection part) is 5um and the width is 20mm. -3 Pa, temperature is 500 ℃, depositing lithium particles with a particle size of 2 μm on the surface of one edge area of ​​the copper foil (3 mm width area), with the lithium particles accounting for half of the area, to obtain a stress buffer layer;

[0049] A 3mm-wide edge region of a rolled lithium ribbon (50µm thick, 100mm wide) was erased to a thickness of 1µm. The stress buffer region on the copper foil and the erased region of the lithium ribbon were then pressure welded together (at a pressure of 50MPa and a temperature of 40°C) to produce a lithium negative electrode with a lithium-copper composite region having a thickness of 55µm. The lithium-copper composite ribbon obtained in this example had a smooth surface.

[0050] Example 2:

[0051] The thickness of the rolled copper foil (collection part) is 3.5um and the width is 15mm. -3Pa, under the condition of temperature of 500°C, lithium particles with a particle size of 1 μm are deposited on the surface of the edge area of ​​one side of the copper foil (5 mm width area), and the area of ​​the lithium particles accounts for three-fifths to obtain a stress buffer layer; Figure 4 shows a physical picture of the lithium metal particles in the stress buffer layer in this embodiment.

[0052] The edge area (5mm wide) on one side of the rolled lithium strip (60um thick, 200mm wide) was rolled to a thickness of 4um; the stress buffer layer area on the copper foil and the rolled area of ​​the lithium strip were welded together by pressure welding (pressure 80MPa, temperature is 30℃) to obtain a lithium negative electrode with a lithium-copper coating area with a thickness of 60um.

[0053] Example 3:

[0054] The thickness of the rolled copper foil (collection part) is 4um and the width is 20mm. -3 Pa, under the condition of temperature of 500℃, lithium particles with a particle size of 1 μm are deposited on the surface of copper foil (3 mm width area), and the lithium particles account for half of the area to obtain a stress buffer layer;

[0055] The edge area (3mm wide) on one side of a rolled lithium strip (50um thick, 500mm wide) was erased to a thickness of 3um; the stress buffer layer area on the copper foil and the erased area of ​​the lithium strip were welded together by pressure welding (pressure 40MPa, temperature is 30℃) to obtain a lithium negative electrode with a lithium-copper cladding area with a thickness of 50um.

[0056] Example 4:

[0057] The thickness of the rolled stainless steel foil (collection part) is 10um and the width is 20mm. -5 Pa, temperature 1000 ℃, deposited on the surface of stainless steel foil (5mm width area) tin particles with a particle size of 1μm, the tin particles accounted for half of the area, to obtain a stress buffer layer;

[0058] The edge area (5mm wide) on one side of a rolled lithium-tin alloy strip (60um thick, 300mm wide, tin content 5%) was rolled to a thickness of 3um; the stress buffer layer area on the stainless steel foil and the rolled-out area of ​​the lithium-tin alloy strip were welded together by pressure welding (pressure 80MPa, temperature is 40℃) to obtain a high-energy-density lithium metal negative electrode product.

[0059] Example 5:

[0060] The thickness of the rolled copper foil (collection part) is 5um and the width is 20mm. -5Pa, temperature is 700 ℃, magnesium particles with a particle size of 2 μm are deposited on the surface of copper foil (3 mm width area), and the area of ​​magnesium particles accounts for one third to obtain a stress buffer layer; Figure 5 shows a physical picture of the magnesium metal particles in the stress buffer layer in this embodiment.

[0061] The edge area (5mm wide) on one side of a rolled lithium-magnesium alloy strip (50um thick, 100mm wide, 10% magnesium content) was erased with a thickness of 3um; the stress buffer layer area on the copper foil and the erased area of ​​the lithium-magnesium alloy strip were welded together by pressure welding (pressure 60MPa, temperature is 30°C) to obtain a high-energy-density lithium metal negative electrode product.

[0062] Example 6:

[0063] The thickness of the rolled copper foil (collection part) is 5um and the width is 20mm. -5 Pa, under the condition of temperature of 700℃, magnesium particles with a particle size of 2 μm are deposited on the surface of copper foil (3 mm width area), and the area of ​​magnesium particles accounts for one third to obtain a stress buffer layer;

[0064] The edge area (5mm wide) on one side of a rolled lithium ribbon (50um thick, 300mm wide) was erased with a thickness of 3um; the stress buffer layer area on the copper foil and the erased area of ​​the lithium ribbon were welded together by pressure welding (pressure 50MPa, temperature is 40℃) to obtain a high-energy-density lithium metal negative electrode product.

[0065] Example 7:

[0066] The high-energy-density lithium metal anode from Example 1 was used as the negative electrode; the NCM ternary cathode was dried at 130°C for 12 hours before battery fabrication; Celgard 2500 was used as the separator, and the electrolyte was 1M LiPF6 with an EC:EMC ratio of 3:7 (vol / vol). The high-energy-density lithium metal anode, NCM ternary cathode, and separator from Example 1 were assembled into a pouch cell using a lamination machine. The cell had a capacity of 2Ah.

[0067] The test voltage range is 3-4.25V, and the charge and discharge current is 0.5C.

[0068] Example 8:

[0069] The high-energy-density lithium metal anode from Example 5 was used as the negative electrode, and the NCM ternary cathode was used as the positive electrode. The cells were dried at 130°C for 12 hours before fabrication. Celgard 2500 was used as the separator, and the electrolyte was 1M LiPF6 with an EC:EMC ratio of 3:7 (vol / vol). The high-energy-density lithium metal anode, NCM ternary cathode, and separator from Example 5 were assembled into a soft-pack battery using a lamination machine. The cell had a capacity of 2Ah. The test voltage range was 3-4.25V, and the charge and discharge current was 0.5C.

[0070] Comparative Example 1:

[0071] The rolled copper foil has a thickness of 5um and a width of 20mm; the rolled lithium strip (60um thick) has a width of 100mm; the edge area on one side of the copper foil (3mm wide) and the edge area on one side of the lithium strip (3mm wide) are rolled together, and the pressure is set to 70MPa. During the production process, it was found that the length of the lithium strip in the rolled laminated area and the unlaminated pure lithium strip area was inconsistent. The laminated area easily pulled the lithium in the unlaminated pure lithium strip area and deformed it. When the length of the product reached about 20 meters, the lithium strip was severely stretched and deformed, and many potholes appeared on the surface of the lithium strip, making it unusable as a negative electrode, so the winding was stopped.

[0072] Comparative Example 2:

[0073] The rolled copper foil (current collecting area) has a thickness of 5um and a width of 120mm; the lithium tape has a thickness of 25um and a width of 100mm. The lithium tape is laminated on both sides to the rolled copper foil to obtain a product with metallic lithium laminated on both sides of the copper foil (using the entire copper foil as the current collecting area).

[0074] The battery was prepared using this negative electrode and an NCM positive electrode, dried at 130°C for 12 hours. A Celgard 2500 separator was used, and the electrolyte was 1M LiPF6 with an EC:EMC ratio of 3:7 (vol / vol). The negative electrode, NCM positive electrode, and separator were assembled into a soft-pack battery using a lamination machine. The cell had a capacity of 2Ah. The test voltage range was 3-4.25V, and the charge and discharge current was 0.5C.

[0075] Table 1: Comparison of specific energy of batteries assembled with different negative electrodes

[0076] As can be seen from Table 1, Examples 7 and 8 use very narrow copper foil as the current collector, and the specific energy can exceed 500wh / kg. Comparative Example 2 uses the entire copper foil as the current collector. Due to the high density of the copper foil and the large area of ​​copper foil used, the specific energy is only 413.5Wh / kg.

[0077] It should be understood that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A lithium battery negative electrode, characterized in that: The negative electrode of the lithium battery is composed of a long strip of lithium or lithium alloy and a current collecting portion combined with at least one side edge of the long strip of lithium or lithium alloy. At least one side edge of the lithium strip or lithium alloy strip has a pre-treated area, the current collecting and gathering portion includes an area with a stress buffer layer, and the pre-treated area and the area with the stress buffer layer overlap each other. The pretreatment is: pretreatment of the area where the lithium strip is to be combined with the tab to form a pretreatment area with a reduced thickness, wherein the pretreatment area has a new metal lithium surface; The stress buffer layer is: the stress buffer layer is composed of protruding discontinuous metal particles in the area where the tab is to be combined with the lithium strip. These protruding particles can be extended and deformed under the action of external force when the tab and the lithium strip are overlapped.

2. The negative electrode of a lithium battery according to claim 1, characterized in that: The current collecting and gathering portion also includes a portion that is not overlapped with the pre-treated area and extends beyond the width of the lithium strip or lithium alloy strip, and the portion is die-cut into a pole ear.

3. The negative electrode of the lithium battery according to claim 1, characterized in that: The lithium belt or lithium alloy belt has a thickness of 0.01-0.15 mm and a width of 10-1500 mm; the width of the pre-treated area is 2-10 mm, and the thickness of the pre-treated area is 0.1-5 um thinner than the thickness of other places. The pre-treatment methods include erasing, rolling and gluing.

4. The negative electrode of the lithium battery according to claim 1, characterized in that: The lithium alloy is formed by a combination of metallic lithium and any one or at least two elements of Ag, Au, Sn, Si, Zn, Al, Mg, In, Ga, B, Mn, Sb, Cr, V, Cu, Fe or Ti.

5. The negative electrode of the lithium battery according to claim 1, characterized in that: The current collecting and gathering part is made of metal foil, and the metal foil is selected from copper foil, nickel foil, stainless steel foil or composite metal current collector; The thickness of the current collecting and converging part is 3-10 um, the width is 12-30 mm, and the width of the stress buffer layer is 2-10 mm.

6. The negative electrode of the lithium battery according to claim 1, characterized in that: The discontinuous raised metal particles in the stress buffer layer are formed by vapor deposition, and the particle size of the metal particles is 1-7um; the raised height of the metal particles is 1-5um; and the area ratio of the metal particles in the stress buffer layer is 1:3 to 9:

10.

7. The negative electrode of the lithium battery according to claim 6, characterized in that: The metal particles include at least one of tin particles, zinc particles, magnesium particles, aluminum particles, silver particles, and lithium particles.

8. The negative electrode of the lithium battery according to claim 1, characterized in that: The pre-treated area and the area of ​​the current collecting and gathering part having the stress buffer layer are laminated together by means of at least one of diffusion welding, ultrasonic welding, resistance welding and pressure welding processes; the width of the laminated area ranges from 2 to 10 mm.

9. A method for preparing a negative electrode for a lithium battery as claimed in any one of claims 1 to 8, comprising: Step 1: depositing discontinuous protruding metal particles on the metal foil through a vapor deposition process to obtain a current collecting and gathering portion with a stress buffer layer covered in a partial area; Step 2: pre-treating at least one side edge region of the lithium strip or lithium alloy strip by at least one of wiping, rolling and gluing to form a pre-treated region with a width of 2-10 mm; Step 3: welding the region with the stress buffer layer of the current collecting and converging portion obtained in step 1 and the pre-treated region of the lithium strip or lithium alloy strip obtained in step 2 together by means of at least one of diffusion welding, ultrasonic welding, resistance welding, and pressure welding, so that the metal particles of the stress buffer layer and the lithium in the lithium strip or lithium alloy strip are fused together to form a fusion region of lithium and metal particles; and Optional step four: die-cutting the portion of the current collecting and gathering portion that is not overlapped with the pre-treated area and extends beyond the width of the lithium strip or lithium alloy strip to form a pole ear.

10. A lithium battery, characterized in that: The lithium battery comprises a lithium battery negative electrode as described in any one of claims 1 to 8, and a positive electrode material is selected from a ternary nickel-cobalt-manganese material, a ternary nickel-cobalt-aluminum material, a lithium-rich manganese-based positive electrode material, lithium iron phosphate, lithium cobalt oxide and a sulfur positive electrode material.

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