Lithium battery composite aluminum foil and preparation method thereof

Abstract

The invention belongs to the technical field of lithium ion batteries, and discloses a lithium battery composite aluminum foil and a preparation method thereof.The lithium battery composite aluminum foil comprises a PET base body, the upper surface and the lower surface of the PET base body are each provided with a transition metal layer, the transition metal layers are the first transition metal layer and the second transition metal layer respectively, the surfaces of the first transition metal layer and the second transition metal layer are each provided with a metal aluminum layer, and the metal aluminum layers are the metal aluminum layers. The metal aluminum layers are respectively a metal aluminum layer I and a metal aluminum layer II. The metal aluminum layer is prepared by adopting an ionic liquid electroplating method and comprises the following steps: a plating solution is room-temperature ionic liquid and is prepared from anhydrous aluminum chloride and pyridine ionic liquid or imidazole ionic liquid, and an additive is introduced into the plating solution, so that the metal aluminum layer is more uniform and compact. According to the method, the nanoscale metal is evaporated on the PET surface through vacuum evaporation to metallize the PET surface, and then the aluminum is electroplated through the ionic liquid to thicken the coating, so that the pain point of vacuum evaporation is solved, and the composite aluminum foil material which is high in performance, low in cost and easy to produce on a large scale is prepared.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion batteries, and in particular relates to a lithium battery composite aluminum foil and a preparation method thereof. Background Art

[0002] With the rapid development of new energy technologies, lithium-ion batteries, as one of the most promising energy storage technologies, have been widely used in portable electronic products, electric vehicles, energy storage systems and other fields. Current collector materials are an important component of lithium batteries. Traditional aluminum foil current collectors are widely used as positive electrode current collectors of lithium batteries due to their excellent conductivity and low cost. With the growth of demand, the performance requirements of lithium batteries in terms of energy density, cycle life, safety and high temperature stability are also getting higher and higher. However, traditional aluminum foil is prone to react with the electrolyte during long-term charging and discharging, resulting in surface oxidation and corrosion, which in turn affects the life and safety of the battery, and can no longer meet the needs of high-performance lithium batteries.

[0003] In recent years, composite aluminum foil materials have emerged. Composite aluminum foil adopts a "sandwich" structure, with polymer materials such as PET (~6μm) as the substrate, and aluminum is evaporated in a high vacuum environment (~1μm on the upper and lower surfaces). PET has the characteristics of insulation, lower melting point, and lower density, which can effectively improve battery safety and weight energy density. However, vacuum evaporation has several major pain points such as high cost, low deposition efficiency, and general coating bonding. Its process route requires that the aluminum wire evaporate at 1400℃ and the PET substrate cool at minus 20℃. It requires repeated evaporation at least a dozen times to deposit 1 micron thick aluminum foil to reduce the internal stress of the coating, and there are high vacuum environment requirements. This process route determines that its cost reduction space is relatively limited, and it may not have the conditions for large-scale mass production at present. Summary of the invention

[0004] The purpose of the present invention is to provide a lithium battery composite aluminum foil and a preparation method thereof to solve the above-mentioned technical problems.

[0005] In order to solve the above technical problems, the specific technical solutions of a lithium battery composite aluminum foil and a preparation method thereof of the present invention are as follows: A lithium battery composite aluminum foil comprises: a PET substrate, wherein the upper and lower surfaces of the PET substrate are respectively provided with a transition metal layer, namely transition metal layer 1 and transition metal layer 2, and the surfaces of the transition metal layer 1 and transition metal layer 2 are respectively provided with a metal aluminum layer, namely metal aluminum layer 1 and metal aluminum layer 2.

[0006] Furthermore, the transition metal layer material includes metal Al, metal Cu, metal Ti or metal Cr, and the thickness of the transition metal layer ranges from 10 to 500 nm; the thickness of the metal aluminum layer is 0.5 to 2 μm, and the metal aluminum is prepared by an ionic liquid electroplating method.

[0007] An ionic liquid aluminum electroplating method comprises the following steps: The plating solution is a room temperature ionic liquid prepared from anhydrous aluminum chloride and a pyridine ionic liquid or an imidazole ionic liquid. Additives are introduced into the plating solution and the solution is fully stirred for electroplating.

[0008] Furthermore, the pyridinium ionic liquid includes N-ethylpyridinium chloride, N-ethylpyridinium bromide, N-ethylpyridinium tetrafluoroborate or N-ethylpyridinium hydrogen sulfate.

[0009] Furthermore, the imidazolium ionic liquid includes 1-methylimidazolium chloride, 1-methylimidazolium tetrafluoroborate, 1-ethylimidazolium chloride, 1-ethylimidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium tetrafluoroborate.

[0010] Furthermore, the molar ratio of the aluminum chloride to the pyrazole ionic liquid or the imidazole ionic liquid is between 1.5 and 2.

[0011] Furthermore, the additive includes nicotinamide, chloronicotinyl chloride, 4-cyanopyridine, o-phenanthroline or cetylpyridinium chloride.

[0012] Furthermore, the bath temperature is 20°C~80°C and the current density is 5 mA / cm 2 ~100 mA / cm 2 The electrodeposition time is 10 min~240 min.

[0013] Furthermore, the stirring method is gas stirring.

[0014] A lithium battery composite aluminum foil of the present invention and a preparation method thereof have the following advantages: ionic liquid has unique advantages such as low melting point, high electrical conductivity, wide electrochemical window, non-flammability and non-volatility, and is an ideal electrolyte for aluminum electroplating. Compared with vacuum evaporation of aluminum, ionic liquid aluminum electroplating is more efficient, more energy-saving and less costly. The present invention uses vacuum evaporation to evaporate nano-scale metals on the surface of PET to metalize it, and then uses ionic liquid aluminum electroplating to thicken the coating, providing an ideal technical path for preparing composite aluminum foil, solving the pain points of vacuum evaporation, and realizing the preparation of high-performance, low-cost, and easy-to-mass-produce composite aluminum foil materials. The successful implementation of this solution is expected to provide a new technical approach for the sustainable development of the lithium battery industry and promote the commercial application of more efficient, safer, and longer-life lithium batteries. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic structural diagram of a new method for preparing a composite aluminum foil for lithium batteries according to the present invention; Figure 2Surface SEM image of Cu-coated PET ionic liquid electroplated aluminum in the embodiment; Figure 3 The surface EDS spectrum of Cu-PET ionic liquid electroplated aluminum in the embodiment; Figure 4 Cross-sectional SEM image of Cu-coated PET ionic liquid electroplated aluminum in the embodiment; Figure 5 EDS spectrum at cross-section position 1 of the Cu-coated PET ionic liquid electroplated aluminum in the embodiment.

[0016] Markings in the figure are as follows: 1, PET substrate; 2, transition metal layer 1; 2', transition metal layer 2; 3, metal aluminum layer 1; 3', metal aluminum layer 2. DETAILED DESCRIPTION

[0017] In order to better understand the purpose, structure and function of the present invention, the following is a further detailed description of a lithium battery composite aluminum foil and a preparation method thereof in conjunction with the accompanying drawings.

[0018] like Figure 1 As shown, a lithium battery composite aluminum foil of the invention comprises: a PET substrate 1, the upper and lower surfaces of the PET substrate 1 respectively have a transition metal layer, namely transition metal layer 1 2 and transition metal layer 2 ', and the surfaces of transition metal layer 1 2 and transition metal layer 2 ' respectively have a metal aluminum layer, namely metal aluminum layer 1 3 and metal aluminum layer 2 3'.

[0019] The transition metal layer material includes but is not limited to metal Al, metal Cu, metal Ti, metal Cr, etc., and its thickness ranges from 10 to 500 nm; the thickness of the metal aluminum layer is 0.5 to 2 μm, and the metal aluminum is prepared by an ionic liquid electroplating method.

[0020] Among them, the process parameters of ionic liquid aluminum electroplating are as follows: The plating solution is a room temperature ionic liquid, which is prepared by anhydrous aluminum chloride and pyridine ionic liquids (including but not limited to N-ethylpyridinium chloride, N-ethylpyridinium bromide, N-ethylpyridinium tetrafluoroborate, N-ethylpyridinium hydrogen sulfate, etc.) or imidazole ionic liquids (including but not limited to 1-methylimidazolium chloride, 1-methylimidazolium tetrafluoroborate, 1-ethylimidazolium chloride, 1-ethylimidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, etc.), and the molar ratio of aluminum chloride to pyrazole ionic liquid or imidazole ionic liquid is between 1.5 and 2. Additives are introduced into the plating solution, and their types include but are not limited to nicotinamide, chloronicotinyl chloride, 4-cyanopyridine, o-phenanthroline, hexadecylpyridinium chloride, etc. The plating solution temperature is 20℃~80℃, and the current density is 5 mA / cm 2 ~100 mA / cm2 The electrodeposition time is 10 min~240 min, and gas stirring is used to stir evenly. Embodiment 1

[0021] The PET substrate is vacuum-deposited with Cu, and then electroplated with ionic liquid aluminum. The process parameters of electroplating aluminum are as follows: The plating solution is composed of anhydrous aluminum chloride (AlCl3) and 1-ethyl-3-methylimidazolium chloride (EMIC), and the molar ratio of AlCl3 to EMIC is 1.5. The additive is 4-cyanopyridine, and the concentration is 2mM. The plating temperature is 25℃ and the current density is 15mA / cm 2 , electrodeposition time was 10 min, and gas stirring was used. Embodiment 2

[0022] The PET substrate is vacuum-deposited with Cu, and then electroplated with ionic liquid aluminum. The process parameters of electroplating aluminum are as follows: The plating solution is composed of anhydrous aluminum chloride (AlCl3) and N-ethylpyridinium tetrafluoroborate, and the molar ratio of AlCl3 to N-ethylpyridinium tetrafluoroborate is 2. The additive is chloronicotinyl chloride with a concentration of 3mM. The plating temperature is 20°C and the current density is 5mA / cm 2 , electrodeposition time was 30 min, and gas stirring was used. Embodiment 3

[0023] The PET substrate is vacuum-deposited with Cu, and then electroplated with ionic liquid aluminum. The process parameters of electroplating aluminum are as follows: The plating solution is composed of anhydrous aluminum chloride (AlCl3) and N-ethylpyridine hydrogen sulfate, and the molar ratio of AlCl3 to N-ethylpyridine hydrogen sulfate is 1.8. The additive is nicotinamide, and the concentration is 3mM. The plating temperature is 80℃ and the current density is 100mA / cm 2 , electrodeposition time was 240 min, and gas stirring was used.

[0024] The surface SEM image (10,000 times) of the Cu-PET ionic liquid electroplated aluminum in Example 1 is as follows: Figure 2 As shown, it can be seen that the aluminum coating is flat, uniform and dense; the surface EDS spectrum of the Cu-PET ionic liquid electroplated aluminum in Example 1 is as follows Figure 3 As shown in the figure, it can be seen that except for the weak signal of the transition layer copper layer, only the aluminum signal is detected, that is, the electroplating of pure aluminum on the Cu-coated PET is achieved. The cross-sectional SEM image (1000 times) of the Cu-coated PET ionic liquid electroplated aluminum in Example 1 is shown in Figure 4 As shown, it can be seen that the interface bonding between the aluminum coating and the copper transition layer is good, and the aluminum layers are uniform and continuous; the EDS spectrum at the cross-section position 1 of the Cu-PET ionic liquid electroplated aluminum in Example 1 is as shown Figure 5 As shown, the EDS spectrum results show that the coating is pure aluminum.

[0025] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the scope of protection of the present invention.

Claims

1. A lithium battery composite aluminum foil, characterized in that: include: A PET substrate (1), wherein the upper and lower surfaces of the PET substrate (1) respectively have a transition metal layer, namely a transition metal layer 1 (2) and a transition metal layer 2 (2'), and the surfaces of the transition metal layer 1 (2) and the transition metal layer 2 (2') respectively have a metal aluminum layer, namely a metal aluminum layer 1 (3) and a metal aluminum layer 2 (3').

2. The lithium battery composite aluminum foil according to claim 1, characterized in that: The transition metal layer material includes metal Al, metal Cu, metal Ti or metal Cr, and the thickness of the transition metal layer ranges from 10 to 500 nm; the thickness of the metal aluminum layer is 0.5 to 2 μm, and the metal aluminum is prepared by an ionic liquid electroplating method.

3. An ionic liquid aluminum electroplating method, characterized in that: The steps include: The plating solution is a room temperature ionic liquid prepared from anhydrous aluminum chloride and a pyridine ionic liquid or an imidazole ionic liquid. Additives are introduced into the plating solution and the solution is fully stirred for electroplating.

4. The ionic liquid aluminum electroplating preparation method according to claim 3, characterized in that: The pyridinium ionic liquid includes N-ethylpyridinium chloride, N-ethylpyridinium bromide, N-ethylpyridinium tetrafluoroborate or N-ethylpyridinium hydrogen sulfate.

5. The ionic liquid aluminum electroplating preparation method according to claim 3, characterized in that: The imidazolium ionic liquid includes 1-methylimidazolium chloride, 1-methylimidazolium tetrafluoroborate, 1-ethylimidazolium chloride, 1-ethylimidazolium p-toluenesulfonate, 1-ethyl-3-methylimidazolium chloride or 1-ethyl-3-methylimidazolium tetrafluoroborate.

6. The method for preparing aluminum by ionic liquid electroplating according to claim 3, characterized in that: The molar ratio of the aluminum chloride to the pyrazole ionic liquid or the imidazole ionic liquid is between 1.5 and 2.

7. The ionic liquid aluminum electroplating preparation method according to claim 3, characterized in that: The additives include nicotinamide, chloronicotinyl chloride, 4-cyanopyridine, o-phenanthroline or cetylpyridinium chloride.

8. The method for preparing aluminum by ionic liquid electroplating according to claim 3, characterized in that: The plating solution temperature is 20℃~80℃, and the current density is 5 mA / cm 2 ~100 mA / cm 2 The electrodeposition time is 10 min~240 min.

9. The ionic liquid electroplating aluminum preparation method according to claim 3, characterized in that: The stirring method is gas stirring.

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