CN110828749B - Modified diaphragm of metal negative electrode battery, preparation method and application - Google Patents

Modified diaphragm of metal negative electrode battery, preparation method and application Download PDF

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Publication number
CN110828749B
CN110828749B CN201910959452.5A CN201910959452A CN110828749B CN 110828749 B CN110828749 B CN 110828749B CN 201910959452 A CN201910959452 A CN 201910959452A CN 110828749 B CN110828749 B CN 110828749B
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diaphragm
negative electrode
battery
film
modified
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CN110828749A (en
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唐永炳
黎重重
周小龙
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Shenzhen Institute of Advanced Technology of CAS
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Shenzhen Institute of Advanced Technology of CAS
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Priority to PCT/CN2020/100430 priority patent/WO2021068575A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/054—Accumulators with insertion or intercalation of metals other than lithium, e.g. with magnesium or aluminium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/431—Inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

The invention provides a modified diaphragm of a metal negative electrode battery, which comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to a negative electrode material, wherein the film comprises a diamond-like carbon film. The diamond-like carbon film has higher intensity, has strengthened the intensity of diaphragm, can hinder the growth of metal dendrite, changes the growth direction of dendrite, makes its horizontal growth, avoids metal dendrite to impale the diaphragm, effectively avoids the battery to lose efficacy because of the impaired short circuit of diaphragm, has improved the security that the battery used, can guide the even deposit of negative pole metal simultaneously, improves the stability of metal negative pole, and then strengthens the circulation stability of battery by a wide margin.

Description

Modified diaphragm of metal negative electrode battery, preparation method and application
Technical Field
The invention relates to the technical field of energy storage devices, in particular to a modified diaphragm of a metal cathode battery, a preparation method and application.
Background
Currently, conventional lithium metal batteries (LIBs) have limited energy density and power density and have failed to meet the increasing urgent need for higher energy density batteries. The development of energy storage batteries with higher energy density and more safety and environmental protection is a current research hotspot.
Taking a lithium metal battery as an example, the lithium metal battery has the advantages of high energy density, low oxidation-reduction potential and the like, and has huge application prospects in the fields of consumer electronics products, electric vehicles, power grid peak shaving, energy storage power supplies, aerospace and the like. The lithium metal battery comprises a positive current collector, a positive electrode, a diaphragm, electrolyte and a negative electrode; the lithium metal battery can greatly improve the performance of the battery, enhance the electric quantity endurance of the battery, greatly improve the economic benefit of electric power storage, promote the upgrading and transformation of consumer electronic products and has great significance to human life, wherein the used diaphragm is selected from a woven film, a non-woven film (non-woven fabric), a microporous film, a composite film, diaphragm paper, a rolled film, a polyolefin diaphragm and the like, but the lithium metal battery has the following problems in the use process that (1) a lithium metal cathode is easy to generate dendrites in the continuous deposition-stripping process, and the dendrites can pierce through the diaphragm to cause the short circuit of the battery to fail; (2) a solid electrolyte layer (SEI film) formed by the reaction of the metal lithium and the electrolyte at the interface is continuously thickened along with time, the interface impedance is continuously increased, the coulombic efficiency is reduced, and the battery capacity is attenuated; (3) since the volume of the lithium metal negative electrode is constantly changed in the charging and discharging processes, the SEI film is unstable, and is continuously generated, cracked and regenerated in the deposition-stripping processes, so that the lithium metal and the electrolyte are consumed. The above problems affect not only the safety performance and the service life of the battery, but also the performance of the battery at a high rate, and limit the use of the lithium metal battery, and therefore, a method for preventing the penetration of the separator or reducing the influence of the growth of lithium dendrites on the lithium metal battery, and improving the safety and stability of the lithium metal battery is urgently required.
Disclosure of Invention
The invention aims to provide a modified diaphragm of a metal cathode battery, a preparation method and application, and aims to solve the problem that the safety and stability of the battery are influenced because the diaphragm of the battery is easily pierced by metal dendrites in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a modified separator for a metal negative electrode battery, the modified separator comprising a porous polyolefin separator and at least a thin film deposited on a surface of the porous polyolefin separator adjacent to a negative electrode material, wherein the thin film comprises a diamond-like carbon thin film.
And the preparation method of the modified diaphragm of the metal negative electrode battery comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to the negative electrode material, wherein the preparation method of the film is any one of a magnetron sputtering method, a plasma chemical vapor deposition method, an ion beam assisted deposition method, a pulse laser deposition method or a filtered cathode vacuum arc deposition method.
And, a secondary battery comprising a positive electrode current collector, a positive electrode active material, a separator, an electrolyte, and a metal negative electrode; the diaphragm is the modified diaphragm of the metal negative electrode battery or the modified diaphragm prepared by the preparation method of the modified diaphragm of the metal negative electrode battery.
The modified diaphragm of the metal negative electrode battery comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to a negative electrode material, wherein the film comprises a diamond-like carbon film. The porous polyolefin diaphragm is modified by adopting a film, and the film comprises a diamond-like carbon film, so that the porous polyolefin diaphragm has the following advantages:
the diamond-like carbon film has stronger chemical inertia, and improves the oxidation resistance and corrosion resistance of the diaphragm; the diamond-like carbon film has strong adhesive force, can be uniformly deposited on the surface of the diaphragm, and keeps the modification effect uniform and smooth; the diamond-like carbon film has higher intensity, has strengthened the intensity of diaphragm, can hinder the growth of metal dendrite, changes the growth direction of dendrite, makes its horizontal growth, avoids metal dendrite to impale the diaphragm, effectively avoids the battery to lose efficacy because of the impaired short circuit of diaphragm, has improved the security that the battery used, can guide the even deposit of negative pole metal simultaneously, improves the stability of metal negative pole, and then strengthens the circulation stability of battery by a wide margin.
The invention also provides a preparation method of the modified diaphragm of the metal negative electrode battery, wherein the modified diaphragm comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to the negative electrode material, and the preparation method of the film is any one of a magnetron sputtering method, a plasma chemical vapor deposition method, an ion beam assisted deposition method, a pulse laser deposition method or a filtered cathode vacuum arc deposition method. The preparation method of the modified diaphragm of the battery is simple, convenient to operate, high in safety and low in cost, cannot damage the diaphragm material, and can ensure that the prepared modified diaphragm of the battery is flat and uniform, thereby being beneficial to subsequent reaction.
The invention also provides a secondary battery, which comprises a positive current collector, a positive electrode, a diaphragm, electrolyte and a metal negative electrode; the diaphragm is the modified diaphragm of the metal negative electrode battery or the modified diaphragm prepared by the preparation method of the modified diaphragm of the metal negative electrode battery. The modified diaphragm is used as the diaphragm of the metal cathode battery, so that the growth of metal dendrites can be effectively hindered, the metal dendrites are prevented from piercing the diaphragm, the safety of the metal cathode battery is improved, and the cycling stability and the high rate of an energy storage device are improved.
Drawings
Fig. 1 is a modified separator structure of a metal negative electrode battery according to an embodiment of the present invention.
Fig. 2 is a schematic structural view of a secondary battery provided in an embodiment of the present invention.
Fig. 3 is a battery performance analysis chart of the secondary battery manufactured by the method of example 1 and the secondary battery manufactured by the method of example 6 according to the present invention.
Detailed Description
In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.
The embodiment of the invention provides a modified diaphragm of a metal negative electrode battery, the structure of the modified diaphragm of the metal negative electrode battery is shown in figure 1, and the modified diaphragm comprises a porous polyolefin diaphragm 1 and at least a thin film 2 deposited on the surface of the porous polyolefin diaphragm 1, which is adjacent to a negative electrode material.
In another embodiment of the present invention, the modified separator includes a porous polyolefin separator and thin films deposited at least on both surfaces of the porous polyolefin separator.
Specifically, the film includes a diamond-like carbon film. Modifying the porous polyolefin diaphragm by adopting a film, wherein the film comprises a diamond-like carbon film which has stronger chemical inertia and improves the oxidation resistance and corrosion resistance of the diaphragm; the adhesive force is strong, the coating can be uniformly deposited on the surface of the diaphragm, and the modification effect is kept uniform and smooth; the diamond-like carbon film has higher intensity, has strengthened the intensity of diaphragm, can hinder the growth of metal dendrite, changes the growth direction of dendrite, makes its horizontal growth, avoids metal dendrite to impale the diaphragm, effectively avoids the battery to lose efficacy because of the impaired short circuit of diaphragm, has improved the security that the battery used, can guide the even deposit of negative pole metal simultaneously, stabilizes the stability of metal negative pole, further strengthens the circulation stability of battery.
Specifically, diamond-like carbon has high hardness, high resistivity, good optical properties, and also has a relatively strong chemical inertness. Diamond-like carbon mainly comprising sp2And sp3Two types of hybrid bonds, and a certain number of C-H bonds are also present in the hydrogen-containing diamond-like film. Preferably, the diamond-like thin film is at least one selected from the group consisting of an amorphous carbon film, a tetrahedral amorphous carbon film, a polymer-like amorphous carbon film, a diamond-like carbon film, and a graphite-like carbon film. In a preferred embodiment of the invention, the diamond-like film in the element doped diamond-like film is selected from an amorphous carbon film or a tetrahedral amorphous carbon film, wherein the amorphous carbon film is mainly formed by sp3And sp2The bond carbon atoms are mixed with each other, and the tetrahedral amorphous carbon film is mainly composed of more than 80% of sp3The bond carbon atom is a skeleton. In a preferred embodiment of the invention, the diamond-like film is a non-hydrogen tetrahedral (ta-C) film.
Preferably, the film is at least one selected from a film formed by diamond-like materials and a diamond-like film doped with elements. In a preferred embodiment of the invention, the film is a doped diamond-like carbon film, and the doped diamond-like carbon film is used as a film material, so that the conductivity, ion conductivity and toughness of the battery can be further improved, the bonding performance of the film and the diaphragm can be improved, the stability can be further improved, the resistivity can be further reduced, and the cycle performance and rate capability of the battery can be improved. Wherein the doping element is a metal element or a nonmetal element.
Preferably, the diamond-like carbon film doped with elements is used as the film deposited on the porous polyolefin diaphragm, and when the doped elements are metal elements, the ion conductivity and toughness of the battery can be further improved, the combination property of the film and the diaphragm can be improved, and the cycle performance and the rate capability of the battery can be improved. More preferably, the doping element is selected from any one of aluminum, titanium, tin, zinc, copper, and the like. In one embodiment of the invention, when the metal element is an aluminum element, the aluminum element-doped diamond-like film is prepared, and the aluminum element-doped diamond-like film is deposited on the surface of the porous polyolefin diaphragm, which is adjacent to the negative electrode material, to obtain the modified diaphragm, so that the ion conduction rate and the heat conductivity of the battery are improved, and the lithium deposition process can also form an aluminum-lithium alloy with aluminum, so that the generation of lithium dendrites is reduced, and the cycle performance and the rate capability of the battery are improved. In another embodiment of the invention, when the metal element is titanium element, the titanium element-doped diamond-like film is prepared, and the titanium element-doped diamond-like film is deposited on the surface of the porous polyolefin diaphragm, which is close to the negative electrode material, to obtain the modified diaphragm, so that the toughness of the modified diaphragm is improved, the bonding performance of the diaphragm and the film is improved, and the adhesive force of the diaphragm is remarkably enhanced.
Preferably, the diamond-like carbon film doped with elements is used as the film deposited on the porous polyolefin diaphragm, and when the doped elements are non-metallic elements, the stability can be further improved, the resistivity can be further reduced, and the cycle performance and the rate capability of the battery can be improved. Preferably, the nonmetal element is selected from any one of fluorine element, nitrogen element, hydrogen element, boron element, silicon element, and the like. In one embodiment of the invention, when the nonmetal element is fluorine element, the fluorine element-doped diamond-like film is prepared, and the fluorine element-doped diamond-like film is deposited on the surface of the porous polyolefin diaphragm, which is close to the negative electrode material, to obtain the modified diaphragm, so that the diaphragm can improve the thermal stability, the corrosion resistance, the wettability of the diaphragm and electrolyte, reduce the dielectric constant and be more beneficial to improving the battery performance. In another embodiment of the invention, when the non-metal element is a nitrogen element, the nitrogen-doped diamond-like thin film is prepared, and the nitrogen-doped diamond-like thin film is deposited on the surface of the porous polyolefin diaphragm, which is close to the negative electrode material, to obtain the modified diaphragm, so that the diaphragm can improve the thermal stability and reduce the resistivity, and is more favorable for improving the battery performance.
Preferably, the film is a single layer structure or a multilayer structure. Preferably, the film is a single-layer structure, and the single-layer structure is a diamond-like carbon film; further preferably, the diamond-like thin film is at least one selected from the group consisting of a non-hydrogen tetrahedral carbon film, a hydrogen-containing tetrahedral carbon film, a non-hydrogen carbon film, a hydrogen-containing carbon film, a high polymer carbon film and a graphite-like carbon film.
Preferably, the film is a single-layer structure, and the single-layer structure is a single-element doped diamond-like film. More preferably, the element is selected from any one of metal elements such as lithium, titanium, aluminum, tin, zinc, and copper, and non-metal elements such as fluorine, nitrogen, hydrogen, boron, and silicon. The diamond-like carbon film doped with elements is adopted as a film to be deposited on the surface of the porous polyolefin diaphragm, which is close to the cathode material, so that the ion conductivity, the heat conductivity, the toughness, the wettability with electrolyte and the like of the battery can be further improved, the combination property of the film and the diaphragm can be improved, the stability can be further improved, the resistivity can be further reduced, and the cycle performance and the rate capability of the battery can be improved.
Preferably, the film is a multilayer structure. The film with the multilayer structure is added, so that the bonding performance of the layer structure in contact with the diaphragm can be improved, and the change of the physical properties of the interface is reduced, so that the contact between the diaphragm and the film material is improved, the bonding capability is improved, the film material is high in bonding capability, is not easy to fall off and is not easy to crack.
Preferably, the film has a multilayer structure of two or more layers, and at least one layer of the multilayer structure is a diamond-like carbon film. In an embodiment of the invention, the film has a multilayer structure with two or more layers, and the multilayer structure is a diamond-like carbon film of the same material. In another embodiment of the present invention, the film is a multilayer structure with two or more layers, and the multilayer structure is a diamond-like film of different materials.
Preferably, the film has a multilayer structure of two or more layers, and at least one layer of the multilayer structure is a single-element diamond-like film. Preferably, the film is a multilayer structure with two or more layers, at least two layers of the multilayer structure are diamond-like carbon films doped with elements, and the types of the doped elements in different layer structures are different.
Preferably, the thickness of the film is 1 to 3 μm. If the thickness is too thin, the effect of enhancing the strength of the diaphragm cannot be achieved, the growth of metal dendrites cannot be well hindered, the growth direction of the dendrites is changed to enable the dendrites to grow transversely, and the situation that the metal dendrites pierce the diaphragm and cannot improve the stability of the battery is avoided. If the thickness is too thick, the prepared film has large internal stress, is easy to damage and crack and fall off in use, and influences long-term use.
Preferably, the material of the porous polyolefin separator is selected from at least one of polypropylene, polyethylene, polypropylene trilayer, polyethylene and polypropylene. Specifically, the polyolefin diaphragm is a polyolefin material with sufficient porosity and an insulating effect, and the structure of the polyolefin diaphragm is a membrane material with a macroscopically smooth and microscopically porous structure. Preferably, the thickness of the porous polyolefin separator is 16 to 25 μm. In a preferred embodiment of the invention, the porous polyolefin separator is selected from polypropylene.
Preferably, the porous polyolefin separator is a single-layer structure or a multi-layer structure; further preferably, the porous polyolefin separator has a multilayer structure, wherein porous polyolefins of different materials are selected for different layer structures of the multilayer structure. In an embodiment of the present invention, the porous polyolefin separator has a multilayer structure, wherein different layers of the multilayer structure are made of porous polyolefins of different materials. The multilayer structure is a first porous polypropylene layer, a polypropylene layer and a polyethylene layer are arranged on any surface of the first porous polypropylene layer, a second porous polypropylene layer is arranged on the surface, deviating from the first porous polypropylene layer, of the polypropylene layer and the polyethylene layer, and a sandwich structure is formed. In another embodiment of the present invention, the porous polyolefin separator has a multi-layer structure, wherein the multi-layer structure is a first porous polypropylene layer, and a polypropylene or polyethylene layer is disposed on either side of the first porous polypropylene layer. In a preferred embodiment of the present invention, the porous polyolefin separator is a monolayer polypropylene with a thickness of 25 μm.
The modified diaphragm of the metal negative electrode battery comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to a negative electrode material, wherein the film comprises a diamond-like carbon film. Modifying the porous polyolefin diaphragm by adopting a film, wherein the film comprises a diamond-like carbon film which has stronger chemical inertia and improves the oxidation resistance and corrosion resistance of the diaphragm; the adhesive has strong adhesive force, can be uniformly deposited on the surface of the metal foil material, and keeps the modification effect uniform and smooth; the diamond-like carbon film has higher intensity, has strengthened the intensity of diaphragm, can hinder the growth of metal dendrite, changes the growth direction of dendrite, makes its horizontal growth, avoids metal dendrite to impale the diaphragm, effectively avoids the battery to lose efficacy because of the impaired short circuit of diaphragm, has improved the security that the battery used, can guide the even deposit of negative pole metal simultaneously, stabilizes the stability of metal negative pole, further strengthens the circulation stability of battery.
The modified diaphragm of the metal negative electrode battery is prepared by the following preparation method of the modified diaphragm of the metal negative electrode battery.
Correspondingly, the embodiment of the invention also provides a preparation method of the modified diaphragm of the metal negative electrode battery, wherein the modified diaphragm comprises a porous polyolefin diaphragm and a film at least deposited on the surface of the porous polyolefin diaphragm adjacent to the negative electrode material, and the preparation method of the film is selected from any one of a magnetron sputtering method, a plasma chemical vapor deposition method, an ion beam assisted deposition method, a pulse laser deposition method or a filtered cathode vacuum arc deposition method. In a preferred embodiment of the present invention, a thin film is disposed on the porous polyolefin separator using a magnetron sputtering method.
Preferably, the preparation method of the modified separator of the metal negative electrode battery comprises the following steps:
s01, providing a porous polyolefin diaphragm, and pretreating the porous polyolefin diaphragm;
s02, placing the porous polyolefin diaphragm obtained through pretreatment in vacuum coating equipment, installing a carbon target, vacuumizing the equipment, introducing argon, setting the diaphragm to rotate, and cleaning a furnace chamber under the conditions that a base is biased at 50-55V and the power of a plasma is 20-25W;
and S03, after the furnace chamber is cleaned, carrying out deposition treatment under the condition of power of 20-25W, and obtaining the modified diaphragm of the battery.
Specifically, in step S01, a porous polyolefin separator is provided and is subjected to a pretreatment; preferably, the pretreatment comprises the following steps: and cutting the porous polyolefin diaphragm into a porous polyolefin diaphragm material with a proper size and a proper shape according to the size of equipment. In a preferred embodiment of the present invention, the porous polyolefin separator is cut into a rectangular shape having a size of 15cm × 3 cm.
Specifically, in the step S02, the porous polyolefin diaphragm obtained by the pretreatment is placed in a vacuum coating device, a carbon target is installed, the inside of the device is vacuumized and argon is introduced, the diaphragm is set to rotate, and the furnace chamber is cleaned under the conditions that the base is biased at 50-55V and the power of the plasma is 20-25W. Preferably, in the step of placing the porous polyolefin membrane obtained by the pretreatment in the vacuum coating equipment, the porous polyolefin membrane obtained by the pretreatment is placed on a circular base with the diameter of 20 cm. Further preferably, the diaphragm is set to rotate, the rotating speed of the diaphragm is 1r/min, the rotating speed is to realize one-time large-area uniform deposition, if the diaphragm does not rotate, the deposition range is limited just under the target, and the substrate is separated from the danger when the diaphragm rotates too fast, and the equipment is damaged by short circuit when the diaphragm contacts with the inner wall of the wall.
Preferably, in the step of vacuumizing the equipment and introducing argon, the vacuum in the equipment is 6-8 multiplied by 10-3Pa; the flow rate of argon gas introduced was 30 sccm. Pressure is proportional to ventilation, with higher ventilation and higher pressure, and pressure is generally controlled by controlling the contemporaneous flow. Among them, argon is an important protective gas for plasma generation by equipment glow starting, and when the gas flow is too small, the plasma is difficult to glow, and when the gas flow is too large, the plasma is unstable.
Preferably, the furnace chamber is cleaned under the conditions that the base is biased to 50-55V and the power of the plasma is 20-25W, the bias is applied to change the moving speed of the plasma after starting, the moving speed is faster when the bias is larger, and therefore a film with higher hardness and density can be obtained; the power of a power supply is also a main influence factor of the structure and the performance of the thin film, more plasmas are generated in a short time when the power is high, the temperature is increased, the annealing effect is also generated, the stress of the thin film is larger, the damage of a deposition target material can be caused when the power is too high, and the low power cannot be started. Preferably, the cleaning time of the furnace chamber is 600s, and if the cleaning time is too long, the cleaning time has no great significance on preparation, but increases the cost; if the cleaning time is too short, impurities may be introduced into the prepared thin film due to unclean cleaning.
In step S03, after the oven chamber is cleaned, carrying out deposition treatment under the condition of power of 20-25W, and obtaining the modified diaphragm of the battery. Preferably, the deposition treatment time is 5h, wherein, too high deposition power and too long deposition time can cause the thickness of the prepared film to be too thick, and the result can bring adverse effects to the battery; conversely, too small a deposition power and too short a deposition time do not exhibit the best effect of modification.
Preferably, after the deposition treatment is finished, the modified diaphragm with the battery is cut into required sizes and placed in a vacuum oven for 12 hours at 60 ℃ for standby.
In some embodiments, the diamond-like film is prepared by a preparation method comprising the following steps:
G01. providing a base material, and pretreating the base material, wherein at least one surface of the base material is a smooth surface;
G02. fixing the base material obtained by pretreatment in a plasma chemical vapor deposition chamber, and vacuumizing until the pressure is 6-8 multiplied by 10-3Pa, introducing argon gas with the flow rate of 30sccm, applying 50V of base bias voltage, and cleaning the base material under the condition that the power is 20W;
G03. introducing argon, setting the bias voltage of the base to be 50V, setting the deposition power of the carbon target to be 20W, controlling the deposition time and doping different types of gases, and preparing DLC films with different hardness and different types.
Specifically, in the step G01, the base material is preferably selected from any one of quartz glass, stainless steel, PMMA, ceramic materials, polymers, and alloy foils. In a preferred embodiment of the invention, a silicon wafer is selected as the base material.
Preferably, in the step of pretreating the base material, the pretreatment method includes: and putting the matrix material into an organic solvent for ultrasonic treatment, and drying the ultrasonically treated matrix material. Further preferably, the drying step is: drying the matrix material subjected to ultrasonic treatment by using an electric heating blower, and finally drying the sample in a blast drying oven at 80 ℃; the purpose of drying by using an electric heating blower is to avoid the marks of liquid drops on the surface of the base material. In the preferred embodiment of the invention, the matrix material is sequentially put into acetone and absolute ethyl alcohol solution for ultrasonic cleaning for 15min, and the ultrasonic cleaning is repeated for three times; the purpose is to remove oil stains and impurities. Preferably, the two solvents are added in amounts of approximately at least 30mL, but the wafer must be submerged
Specifically, in step G02, the base material obtained by the pretreatment is fixed in a plasma chemical vapor deposition chamber, the chamber is vacuumized until the pressure is 6-8 x10 < -3 > Pa, argon gas with the flow rate of 30sccm is introduced, a base bias voltage of 50V is applied, and the base material is cleaned under the condition of the power of 20W. Among them, argon is an important protective gas for plasma generation by equipment glow starting, and when the gas flow is too small, the plasma is difficult to glow, and when the gas flow is too large, the plasma is unstable. The bias voltage is applied to change the moving speed of the plasma after starting, and the larger the bias voltage is, the faster the moving speed is, so that a film with higher hardness and density can be obtained; the power of a power supply is also a main influence factor of the structure and the performance of the thin film, more plasmas are generated in a short time when the power is high, the temperature is increased, the annealing effect is also generated, the stress of the thin film is larger, the damage of a deposition target material can be caused when the power is too high, and the low power cannot be started.
Preferably, the cleaning time for cleaning the base material is 10-15 min.
Specifically, argon gas is introduced in the step G03, the bias voltage of the base is set to be 50V, the deposition power of the carbon target is set to be 20W, and the deposition time is controlled and different types of gases are doped to prepare DLC films with different hardness and different types. Preferably, the deposition time is 15min to 10 h. The deposition time is controlled to prepare DLC films with different hardness and different types. Specifically, the bias voltage of the base is set to be 50V, and if the applied bias voltage is too small, the DLC film is a common amorphous DLC film or an amorphous carbon film with low hydrogen content; if the bias voltage is too large, the film becomes a hydrogen-containing DLC film.
The preparation method of the modified diaphragm of the metal cathode battery is simple, convenient to operate, high in safety and low in cost, cannot damage the diaphragm material, can ensure that the prepared modified diaphragm of the battery is flat and uniform, and is beneficial to subsequent reaction.
Correspondingly, the invention also provides a secondary battery, the structure of which is shown in fig. 2, the secondary battery comprises a positive electrode current collector 1, a positive electrode active material 2, an electrolyte 3, a diaphragm 4 and a metal negative electrode 5, wherein the diaphragm 4 comprises a porous polyolefin diaphragm 6 and a thin film 7 deposited on any surface of the porous polyolefin diaphragm 6.
The diaphragm is the modified diaphragm of the metal negative electrode battery or the modified diaphragm prepared by the preparation method of the modified diaphragm of the metal negative electrode battery.
Preferably, the positive current collector is an alloy material or a composite material; further preferably, the material of the positive electrode current collector is selected from any one of aluminum, magnesium, vanadium, copper, iron, tin, zinc, nickel, titanium, manganese, and aluminum. In some embodiments, the positive electrode current collector is an alloy material containing at least one of the above-described metal elements; in other embodiments, the positive electrode current collector is a composite material containing at least one of the above metal elements. In a preferred embodiment of the present invention, the material of the positive electrode current collector is a carbon-coated aluminum foil.
Preferably, the positive active material includes an active material, a conductive agent, and a binder. Further preferably, the active material is selected from any one of lithium cobaltate, lithium iron phosphate and nickel cobalt manganese ternary material. In a preferred embodiment of the present invention, the positive electrode active material is lithium iron phosphate.
Preferably, the conductive agent is at least one selected from conductive carbon black, conductive carbon spheres, conductive graphite, carbon nanotubes, conductive carbon fibers, graphene and reduced graphene oxide. In a preferred embodiment of the present invention, the conductive agent is conductive carbon black.
Preferably, the binder is at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polyvinyl alcohol, carboxymethyl cellulose, SBR rubber, and polyolefin. In a preferred embodiment of the invention, the binder is polyvinylidene fluoride.
Preferably, the mass percentage of the positive electrode material is 100%, the mass percentage of the positive electrode active material is 60-95%, the mass percentage of the conductive agent is 5-30%, and the mass percentage of the binder is 5-10%.
In a preferred embodiment of the present invention, the method for preparing the positive electrode comprises the steps of:
providing a positive current collector material, and treating the surface of the positive current collector material;
q02, weighing the positive active material, the conductive agent and the binder according to the addition amount, and adding a solvent to fully mix to form uniform slurry; and uniformly coating the slurry on any surface of a positive current collector to form a positive active material layer, drying, pressing after complete drying and cutting to obtain the battery positive electrode with the required size.
Specifically, in the step Q01, the surface of the positive electrode current collector material is treated by cleaning, and the cleaning is performed alternately with an organic solvent and deionized water to remove excess impurities.
Specifically, in the above step Q02, the solvent is selected from N-methylpyrrolidone. Preferably, in the step of drying, the temperature of drying is 80-85 ℃, and the time of drying is 11-12 hours.
Specifically, the diaphragm is the modified diaphragm of the metal negative electrode battery or the modified diaphragm prepared by the preparation method of the modified diaphragm of the metal negative electrode battery. The modified diaphragm comprises a porous polyolefin diaphragm and a film deposited on any surface of the porous polyolefin diaphragm, wherein the film comprises a diamond-like carbon film material. In a preferred embodiment of the invention, the porous polyolefin separator is selected from a monolayer of polypropylene, having a thickness of 25 μm; the diamond-like carbon film material is a single-layer non-hydrogen tetrahedral (ta-C) film, and the thickness of the film is 1 mu m. The modified diaphragm is in a disc shape, and the diameter of the modified diaphragm is 16 mm.
Preferably, the electrolyte is a certain amount of lithium salt electrolyte added into the non-aqueous solvent, and the obtained product is dissolved after fully stirring, and the concentration of the electrolyte is preferably 0.1-10 mol/L.
Further preferably, in the electrolytic solution, the lithium salt electrolyte is selected from any one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium trifluoromethanesulfonate, lithium difluorosulfonimide, lithium bistrifluorosulfonimide lithium chloride, lithium fluoride, lithium sulfate, lithium carbonate, lithium phosphate, lithium nitrate, lithium difluorooxalato borate, lithium hexafluoroarsenate, and lithium bisoxalato borate. In a preferred embodiment of the invention, the lithium salt electrolyte is selected from lithium hexafluorophosphate.
Further preferably, in the electrolyte, the nonaqueous solvent includes one or more of esters, ethers, and sulfones, for example, any one of diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, dimethyl sulfone or dimethyl ether, 1, 3-dioxolane, and ethylene carbonate. In a preferred embodiment of the present invention, the nonaqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1: 1.
In a preferred embodiment of the present invention, the electrolyte is prepared by the following method: weighing a certain amount of two or more lithium salt electrolytes, adding the two or more lithium salt electrolytes into a non-aqueous solvent, and fully stirring and dissolving to obtain the required electrolyte.
Preferably, the metal negative electrode is selected from any one of lithium, sodium, potassium, and zinc.
The invention also provides a secondary battery, which comprises a positive current collector, a positive electrode, a diaphragm, electrolyte and a metal negative electrode; the diaphragm is the modified diaphragm of the metal negative electrode battery or the modified diaphragm prepared by the preparation method of the modified diaphragm of the metal negative electrode battery. The modified diaphragm is used as the diaphragm of the metal cathode battery, so that the growth of metal dendrites can be effectively hindered, the metal dendrites are prevented from piercing the diaphragm, the safety of the metal cathode battery is improved, and the cycling stability and high rate performance of an energy storage device are improved.
Correspondingly, the invention also provides a preparation method of the secondary battery, which comprises the following steps:
D01. preparing a negative electrode: cutting the lithium metal foil to directly serve as a battery cathode;
D02. preparing an electrolyte: weighing a certain amount of lithium salt electrolyte, adding the lithium salt electrolyte into a non-aqueous solvent, and fully stirring to obtain electrolyte with the concentration of 0.1-10 mol/L;
D03. preparing a diaphragm: selecting the preparation method of the modified diaphragm of the metal cathode battery to prepare the modified diaphragm;
D04. preparing a positive electrode: weighing the positive active material, the conductive agent and the binder according to a certain proportion, adding a proper solvent, and fully mixing to obtain uniform slurry to prepare a positive active material layer; providing a positive current collector, cleaning, then uniformly coating a positive active material layer on the surface of the positive current collector in a certain thickness, and cutting the positive active material layer into a certain size after the positive active material layer is completely dried to prepare the positive electrode.
D05. And assembling the battery. And providing inert gas or an anhydrous oxygen-free environment, stacking or winding the anode, the diaphragm and the cathode into a battery core in sequence, dropwise adding a proper amount of electrolyte to completely soak the diaphragm, and packaging the diaphragm in the shell to obtain the secondary battery.
The preparation method of the secondary battery is simple and rapid. The modified diaphragm prepared by the preparation method of the modified diaphragm of the metal cathode battery is used as the battery diaphragm, so that the secondary battery has excellent electrochemical performance, good cycle stability and long service life.
Now, the description will be further described with reference to specific examples.
Example 1
And respectively preparing and assembling a battery anode, a battery cathode, electrolyte and a diaphragm, wherein the diaphragm is a modified diaphragm of the fluorine metal cathode battery.
Preparing a modified diaphragm of the metal negative electrode battery: the modified diaphragm of the metal cathode battery is prepared by adopting a magnetron sputtering method, and the preparation method comprises the following steps:
providing a porous polyolefin diaphragm, and pretreating the porous polyolefin diaphragm; the porous polyolefin diaphragm is a porous polypropylene diaphragm;
placing the porous polyolefin diaphragm obtained by pretreatment in vacuum coating equipment, installing a carbon target, vacuumizing the equipment and introducing argon, and controlling the vacuum in the equipment to be 6 multiplied by 10-3Pa; the flow rate of argon gas introduced was 30 sccm. Setting the diaphragm to rotate at the rotating speed of 1r/min, and cleaning the furnace chamber for 10min under the conditions that the base is biased at 50V and the power of the plasma is 20W;
and after the furnace chamber is cleaned, carrying out deposition treatment under the condition of 20W of power, wherein the deposition treatment time is 5h, cutting the modified diaphragm with the battery into 16mm after the deposition treatment is finished, placing the cut modified diaphragm in a vacuum oven, and obtaining the modified diaphragm of the battery after the modified diaphragm is placed in the vacuum oven for 12h at the temperature of 60 ℃.
Taking the modified diaphragm as a diaphragm; lithium foil as a negative electrode; in the electrolyte, the lithium salt electrolyte is selected from lithium hexafluorophosphate, the nonaqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and LiPF with the concentration of 1mol/L is prepared6(ii) a And preparing a positive electrode by taking lithium iron phosphate as a positive electrode active material, and assembling the battery. In the prepared battery, the diaphragm is a modified diaphragm of the fluorine metal negative electrode battery.
Example 2
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal cathode battery by adopting the magnetron sputtering method, the deposition treatment time is 5h and is replaced by 10 h; other steps were the same as in example 1, and a battery was manufactured.
Example 3
Compared with the mode of the embodiment 1, in the step of preparing the modified diaphragm of the metal cathode battery by adopting a magnetron sputtering method, the deposition treatment time is changed from 5h to 2 h; other steps were the same as in example 1, and a battery was manufactured.
Example 4
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal cathode battery by adopting the magnetron sputtering method, the deposition treatment time is changed from 5h to 1 h; other steps were the same as in example 1, and a battery was manufactured.
Example 5
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the deposition treatment time is changed from 5h to 0.5 h; other steps were the same as in example 1, and a battery was manufactured.
Example 6
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the porous polyolefin diaphragm is a porous polypropylene diaphragm instead of the porous polyolefin diaphragm; other steps were the same as in example 1, and a battery was manufactured.
Example 7
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the porous polyolefin diaphragm is a porous polypropylene diaphragm instead of the porous polyolefin diaphragm; the deposition treatment time is 5h, and is replaced by 10 h; other steps were the same as in example 1, and a battery was manufactured.
Example 8
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the porous polyolefin diaphragm is a porous polypropylene diaphragm instead of the porous polyolefin diaphragm; the deposition treatment time is 5h, and is replaced by 2 h; other steps were the same as in example 1, and a battery was manufactured.
Example 9
And respectively preparing and assembling a battery anode, a battery cathode, electrolyte and a diaphragm, wherein the diaphragm is a modified diaphragm of the fluorine metal cathode battery.
Preparing a modified diaphragm of the metal negative electrode battery: the modified diaphragm of the metal negative electrode battery is prepared by adopting a method of a filtering cathode vacuum arc deposition method, and the preparation method comprises the following steps:
selecting a high-purity cylindrical carbon target material as a target material; providing a porous polypropylene film as a base material and fixing the porous polypropylene film on equipment;
the vacuum chamber of the equipment is closed, and the vacuum value is 5x10-5Pa (about 3 h); after vacuumizing, opening an argon valve and introducing argon (Ar) gas with the flow of 20 SCCM; after the airflow is stable, the pulse bias power supply is turned on, set to be 100-500V and applied to the sample platform; starting a jet bias power supply to start Ar, bombarding the base material, and cleaning for 10-30 min; and starting a high-voltage arc power supply with the power of 100-1500W, and controlling the deposition time to be 5h to obtain the modified diaphragm of the battery.
Taking the modified diaphragm as a diaphragm; lithium foil as a negative electrode; in the electrolyte, the lithium salt electrolyte is selected from lithium hexafluorophosphate, the nonaqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and LiPF with the concentration of 1mol/L is prepared6(ii) a And preparing a positive electrode by taking lithium iron phosphate as a positive electrode active material, and assembling the battery. In the prepared battery, the diaphragm is a modified diaphragm of the fluorine metal negative electrode battery.
Example 10
Compared with the mode of example 9, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the filtered cathode vacuum arc deposition method, the deposition time is changed from 5h to 10 h; other steps were the same as in example 9, and a battery was manufactured.
Example 11
Compared with the mode of example 9, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the filtered cathode vacuum arc deposition method, the deposition time is changed from 5h to 12 h; other steps were the same as in example 9, and a battery was manufactured.
Example 12
Compared with the mode of example 9, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the filtered cathode vacuum arc deposition method, the deposition time is changed from 5h to 1 h; other steps were the same as in example 9, and a battery was manufactured.
Example 13
Compared with the mode of example 9, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the filtered cathode vacuum arc deposition method, the deposition time is changed from 5h to 0.5 h; other steps were the same as in example 9, and a battery was manufactured.
Example 14
And respectively preparing and assembling a battery anode, a battery cathode, electrolyte and a diaphragm, wherein the diaphragm is a modified diaphragm of the fluorine metal cathode battery.
Preparing a modified diaphragm of the metal negative electrode battery: the modified diaphragm of the metal cathode battery is prepared by adopting a plasma enhanced chemical vapor deposition method, and the preparation method comprises the following steps:
selecting a polypropylene film as a base material, and fixing the polypropylene film in the equipment; the vacuum chamber of the equipment is closed, and the vacuum value is 5x10- 5Pa (about 3 h); opening an argon valve and introducing argon (Ar) gas with the flow of 20 SCCM; after the airflow is stable, the pulse bias power supply is turned on, set to be 100-500V and applied to the sample platform; starting a jet bias power supply to start Ar, bombarding the base material, and cleaning for 10-30 min; opening a gas valve of a carbon source (methane, acetylene, tetrafluoromethane, trimethylborane and the like), controlling the flow to be 5-30SCCM, and simultaneously opening Ar gas with the flow of 20SCCM and stable entrained gas flow; and starting a radio frequency power supply, controlling the power to be 10-100W, generating carbon source argon gas mixed plasma, and setting the deposition time to be 5h to obtain the modified diaphragm of the battery.
Taking the modified diaphragm as a diaphragm; lithium foil as a negative electrode; in the electrolyte, the lithium salt electrolyte is selected from lithium hexafluorophosphate, the nonaqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and LiPF with the concentration of 1mol/L is prepared6(ii) a And preparing a positive electrode by taking lithium iron phosphate as a positive electrode active material, and assembling the battery. In the prepared battery, the diaphragm is a modified diaphragm of the fluorine metal negative electrode battery.
Example 15
Compared with the mode of example 14, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the method of the vapor deposition of the plasma enhanced chemistry, the deposition time is changed from 5h to 10 h; other steps were the same as in example 9, and a battery was manufactured.
Example 16
Compared with the mode of example 14, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the method of the plasma enhanced chemical vapor deposition, the deposition time is changed from 5h to 2 h; other steps were the same as in example 9, and a battery was manufactured.
Example 17
Compared with the mode of example 14, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the method of the vapor deposition of the plasma enhanced chemistry, the deposition time is changed from '5 h' to '1 h'; other steps were the same as in example 9, and a battery was manufactured.
Example 18
Compared with the mode of example 14, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the method of the vapor deposition of the plasma enhanced chemistry, the deposition time is changed from '5 h' to '0.5 h'; other steps were the same as in example 9, and a battery was manufactured.
Comparative example 1
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal cathode battery by adopting the magnetron sputtering method, the deposition treatment time is changed from 5h to 0 h; other steps were the same as in example 1, and a battery was manufactured.
Comparative example 2
Compared with the mode of example 9, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the filtered cathode vacuum arc deposition method, the deposition time is changed from 5h to 0 h; other steps were the same as in example 9, and a battery was manufactured.
Example 19
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the vacuum in the control equipment is 6 multiplied by 10-3Pa "alternative" the vacuum in the control device was 7X 10-3Pa'; other steps were the same as in example 1, and a battery was manufactured.
Example 20
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the vacuum in the control equipment is 6 multiplied by 10-3Pa "alternative" the vacuum in the control device was 8X 10-3Pa'; other steps and implementationsA battery was fabricated in the same manner as in example 1.
Example 21
Compared with the mode of the embodiment 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the base bias voltage of 50V is replaced by the base bias voltage of 52V; other steps were the same as in example 1, and a battery was manufactured.
Example 22
Compared with the mode of the embodiment 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the base bias voltage of 50V is replaced by the base bias voltage of 54V; other steps were the same as in example 1, and a battery was manufactured.
Example 23
Compared with the mode of the embodiment 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting a magnetron sputtering method, the base bias voltage of 50V is replaced by the base bias voltage of 55V; other steps were the same as in example 1, and a battery was manufactured.
Example 24
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the power of the plasma is replaced by 20W; other steps were the same as in example 1, and a battery was manufactured.
Example 25
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the power of the plasma is replaced by 'the power of the plasma is 25W'; other steps were the same as in example 1, and a battery was manufactured.
Example 26
Compared with the mode of example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the power of the plasma is replaced by 'the power of the plasma is 25W'; other steps were the same as in example 1, and a battery was manufactured.
Example 27
Compared with the mode of the example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the deposition treatment under the condition of the power of 20W is replaced by the deposition treatment under the condition of the power of 22W; other steps were the same as in example 1, and a battery was manufactured.
Example 28
Compared with the mode of the example 1, in the step of preparing the modified diaphragm of the metal negative electrode battery by adopting the magnetron sputtering method, the deposition treatment under the condition of the power of 20W is replaced by the deposition treatment under the condition of the power of 25W; other steps were the same as in example 1, and a battery was manufactured.
Example 29
In contrast to the manner of example 1, "sodium foil as a negative electrode" was replaced with "sodium foil as a negative electrode"; other steps were the same as in example 1, and a battery was manufactured.
Example 30
In contrast to the mode of example 1, "potassium foil as the negative electrode" was replaced with "potassium foil as the negative electrode"; other steps were the same as in example 1, and a battery was manufactured.
Example 31
In contrast to the manner of example 1, "zinc foil as a negative electrode" was replaced with "zinc foil as a negative electrode"; other steps were the same as in example 1, and a battery was manufactured.
Example 32
In contrast to the manner of example 1, "the lithium salt electrolyte is selected from lithium hexafluorophosphate" instead of "the lithium salt electrolyte is selected from lithium tetrafluoroborate"; other steps were the same as in example 1, and a battery was manufactured.
Example 33
In contrast to the manner of example 1, "the lithium salt electrolyte is selected from lithium hexafluorophosphate" instead of "the lithium salt electrolyte is selected from lithium perchlorate"; other steps were the same as in example 1, and a battery was manufactured.
Example 34
Compared with the mode of the example 1, the non-aqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and the non-aqueous solvent is dimethyl carbonate; other steps were the same as in example 1, and a battery was manufactured.
Example 35
Compared with the mode of the example 1, the nonaqueous solvent is a mixture of ethylene carbonate and diethyl carbonate in a volume ratio of 1:1, and the nonaqueous solvent is methyl ethyl carbonate; other steps were the same as in example 1, and a battery was manufactured.
Example 36
In contrast to the mode of example 1, "LiPF was prepared at a concentration of 1mol/L6"alternative" preparation to give a concentration of 0.1mol/L LiPF6"; other steps were the same as in example 1, and a battery was manufactured.
Example 37
Compared with the mode of the embodiment 1, the method that the lithium iron phosphate is used as the positive electrode active material to prepare the positive electrode is replaced by the method that lithium cobaltate is used as the positive electrode active material to prepare the positive electrode; other steps were the same as in example 1, and a battery was manufactured.
Example 38
Compared with the mode of the embodiment 1, the method that the lithium iron phosphate is used as the positive active material to prepare the positive electrode is replaced by the method that the nickel-cobalt-manganese ternary material is used as the positive active material to prepare the positive electrode; other steps were the same as in example 1, and a battery was manufactured.
The batteries prepared by the preparation methods of the examples 1 to 18 and the comparative examples 1 to 2 are cycled at a rate of 10 ℃ and analyzed for specific performances of the batteries, the analysis results are shown in table 1, and the secondary batteries with the separators prepared by the examples 1 to 18 being modified separators of the prepared metal cathode batteries have cycle times of not less than 90, maximum cycle times of 195 and maximum cycle times, and the modified separators are prepared by depositing the modified separators on a PP film for 5 hours by adopting the magnetron sputtering method of the example 1. In the secondary battery with the capacity retention rate of not less than 75 percent and the maximum capacity retention rate of 83 percent, the modified diaphragm is prepared by depositing and processing the PE film for 10 hours by adopting the magnetron sputtering method in the embodiment 7. The secondary battery adopting the modified diaphragm of the metal cathode battery can effectively improve the cycle times and the capacity retention rate, so that the secondary battery has excellent electrochemical performance and the cycle stability of the secondary battery is improved.
TABLE 1
Figure BDA0002228435680000221
Figure BDA0002228435680000231
The modified diaphragm prepared in the example 1 is selected as a diaphragm, lithium iron phosphate is selected as a positive electrode active material, and 1mol/L LiPF is selected6The modified diaphragm is prepared by depositing and treating a PP film for 5 hours by adopting the magnetron sputtering method in the embodiment 1; selecting the secondary battery prepared in the embodiment 6, wherein in the preparation method of the secondary battery, the deposition treatment time is 0h, and other conditions are the same as those of the preparation method in the embodiment 1; the performance of the secondary batteries of the above examples 1 and 6 was analyzed and compared, and the cycle number of each battery was analyzed as shown in fig. 3, so that the cycle life of the secondary battery prepared in example 1 reached 200 cycles; the cycle life of the secondary battery prepared in example 6 was about 100 cycles; the specific capacity of each battery is analyzed, and when the number of circulating turns of the secondary battery prepared in the embodiment 1 reaches 200 turns, the discharge specific capacity still maintains 60 mAh/g; coulombic efficiency approaches 100%; when the cycle of the secondary battery prepared in example 6 reaches 100 cycles, the specific discharge capacity is reduced to 60 mAh/g. Thus, the modified diaphragm is used as the diaphragm, the lithium iron phosphate is used as the positive electrode active material, and 1mol/L LiPF is used in the preparation of example 16The modified diaphragm is prepared by depositing and treating a PP film for 5 hours by adopting the magnetron sputtering method in the embodiment 1; the secondary battery can maintain better cycle number and higher specific capacity.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

1. A modified membrane of a metal negative electrode battery, which is characterized by comprising a porous polyolefin membrane and a thin film at least deposited on the surface of the porous polyolefin membrane adjacent to a metal negative electrode material, wherein the thin film comprises a diamond-like carbon thin film; the thickness of the film is 1-3 mu m; the thickness of the porous polyolefin diaphragm is 16-25 mu m, and the porous polyolefin diaphragm is of a multilayer structure; the metal negative electrode is any one of lithium, sodium, potassium and zinc, and the modified diaphragm can prevent dendritic crystals of the lithium, sodium, potassium and zinc from piercing the diaphragm, so that the safety and stability of the metal negative electrode battery are ensured.
2. The modified separator for a metal negative electrode battery according to claim 1, wherein said thin film is at least one selected from the group consisting of a thin film formed of a diamond-like material and a diamond-like thin film doped with an element.
3. The modified separator for a metal negative electrode battery according to claim 2, wherein the diamond-like thin film is at least one selected from the group consisting of a non-hydrogen carbon film, a high polymer-like carbon film and a graphite-like carbon film.
4. The modified separator for a metal negative electrode battery according to any one of claims 1 to 3, wherein the thin film has a single-layer structure or a multi-layer structure.
5. The modified separator for a metal negative electrode battery according to claim 4, wherein the thin film is a single-layer structure, and the single-layer structure is a single-element-doped diamond-like thin film.
6. The modified separator for a metal negative electrode battery according to claim 4, wherein the thin film has a multilayer structure of two or more layers, and at least one layer of the multilayer structure is a diamond-like thin film, or;
the film is a multilayer structure with two or more layers, and at least one layer in the multilayer structure is a diamond-like film with a single element, or;
the film is of a multilayer structure with two or more layers, at least two layers of the multilayer structure are diamond-like carbon films doped with elements, and the types of the doped elements in different layer structures are different.
7. The modified separator of a metal negative electrode battery according to any one of claims 1 to 3, wherein the material of the porous polyolefin separator is at least one selected from polypropylene and polyethylene.
8. The method for preparing a modified separator of a metal negative electrode battery according to claim 1, wherein the modified separator comprises a porous polyolefin separator and at least one thin film deposited on the surface of the porous polyolefin separator adjacent to the negative electrode material, wherein the thin film is prepared by any one method selected from magnetron sputtering, plasma chemical vapor deposition, ion beam assisted deposition, pulsed laser deposition, or filtered cathode vacuum arc deposition.
9. A secondary battery, characterized in that the secondary battery comprises a positive current collector, a positive active material, a separator, an electrolyte and a metal negative electrode; the separator is the modified separator of the metal negative electrode battery of any one of claims 1 to 7 or the modified separator prepared by the preparation method of the modified separator of the metal negative electrode battery of claim 8.
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