WO2021017801A1 - 功能化隔离膜、其制备方法、锂金属电池和包含锂金属电池的装置 - Google Patents

功能化隔离膜、其制备方法、锂金属电池和包含锂金属电池的装置 Download PDF

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WO2021017801A1
WO2021017801A1 PCT/CN2020/101668 CN2020101668W WO2021017801A1 WO 2021017801 A1 WO2021017801 A1 WO 2021017801A1 CN 2020101668 W CN2020101668 W CN 2020101668W WO 2021017801 A1 WO2021017801 A1 WO 2021017801A1
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lithium
functionalized
optionally
inorganic particles
group
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PCT/CN2020/101668
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English (en)
French (fr)
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刘成勇
郭永胜
范铨
张涛
梁成都
杨军
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宁德时代新能源科技股份有限公司
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Priority to EP20846846.2A priority Critical patent/EP3955357A4/en
Publication of WO2021017801A1 publication Critical patent/WO2021017801A1/zh
Priority to US17/556,987 priority patent/US20220115689A1/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
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/443—Particulate material
    • 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
    • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
    • 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
    • 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
    • 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
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • 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

Definitions

  • This application belongs to the technical field of energy storage devices, and specifically relates to a functionalized isolation film and a lithium metal battery.
  • the first aspect of the present application provides a functionalized isolation film, which includes a porous substrate and a functional film layer disposed on at least one side of the porous substrate; wherein, the functional film layer includes inorganic particles, which can interact with metal lithium.
  • the reversible reaction forms a lithium alloy.
  • the functionalized isolation film provided in the present application includes a functional film layer, and the functional film layer contains inorganic particles, which can reversibly react with metallic lithium to form a lithium alloy.
  • the functionalized separator is used in a lithium metal battery and the functional film layer is in contact with lithium metal, under the action of the electrolyte, the inorganic particles and the metal lithium react reversibly to form a lithium alloy in situ, thereby changing the lithium composition on the surface of the metal lithium electrode .
  • the formation of lithium alloys can regulate the behavior of lithium ion deposition/dissolution, effectively inhibit the growth of dendrites of lithium metal electrodes, and help improve the reversibility of the lithium ion deposition/dissolution process in lithium metal electrodes. Therefore, the use of the functionalized isolation membrane of the present application can improve the first-time coulombic efficiency, cycle performance and safety performance of the lithium metal battery.
  • the volume average particle diameter D v 50 of the inorganic particles may be 10 nm to 20 ⁇ m, optionally 50 nm to 10 ⁇ m, and further optionally 200 nm to 2 ⁇ m.
  • the inorganic particles have an appropriate particle size, which can improve the capacity and cycle performance of the battery.
  • the inorganic particles can be selected from one or more of silicon, silicon-oxygen compound SiO a , magnesium, aluminum, zinc, indium, antimony, silver, gold, germanium, and tin, where 0 ⁇ a ⁇ 2.
  • At least part of the surface of the inorganic particles is coated with a polymer coating layer, and the coating layer contains a group capable of reversibly bonding with lithium ions.
  • the coating layer contains groups that can reversibly bond with lithium ions.
  • the group reacts with the lithium alloy in situ to carry out the reversible bonding with the lithium ion, thereby improving the binding fastness of the coating layer and the inorganic particles. Therefore, the coating layer can better suppress the volume change of the lithium alloy during the charging and discharging of the battery.
  • the chemical bond formed in situ between the groups of the coating layer and lithium ions can also serve as a channel for lithium ion transfer, which can promote the transfer of lithium ions and improve the dynamic performance of the metal lithium electrode. Therefore, the functional isolation membrane can further improve the first-time coulombic efficiency, cycle performance and safety performance of lithium metal batteries.
  • the groups that reversibly bond with lithium ions include one or more of acid radicals, amino groups, imino groups, sulfhydryl groups, and polysulfide groups (-S b -, b ⁇ 2).
  • the acid radical group includes one or more of a carboxylic acid group, a sulfonic acid group, a sulfinic acid group, and a phosphoric acid group.
  • the coating layer includes a polyenoic acid containing the acid radical group.
  • the polyolefin acid includes one or more of polyacrylic acid and polyvinylbenzenesulfonic acid.
  • the surface of the inorganic particles is coated with a suitable coating layer, which can further improve the cycle performance, first coulombic efficiency and safety performance of the battery.
  • the thickness of the coating layer is 1 nm to 1 ⁇ m, optionally 5 nm to 200 nm, and further optionally 20 nm to 100 nm.
  • the coating layer has an appropriate thickness, which can improve the first coulombic efficiency and cycle performance of the battery.
  • the functional film layer further includes a polymer ionic liquid.
  • the functional membrane layer may also include polymer ionic liquid.
  • the structure of polymer ionic liquids contains positively charged groups and negatively charged groups.
  • the positively charged groups can interact with the groups of the polymer coating layer that reversibly bond with lithium ions, so that the polymer ionic liquid and the polymer of the coating layer can be physically cross-linked, thereby improving the strength and strength of the functional film layer.
  • Electrolyte resistance The negatively charged group is beneficial to enhance the transfer rate of the positive charge of lithium ions and reduce the impedance and overpotential. Therefore, the functional isolation membrane can further improve the first-time coulombic efficiency, cycle performance and safety performance of lithium metal batteries.
  • the polymer ionic liquid comprises structural units represented by formula I and formula II;
  • X is a negatively charged anion, is optional -COO -, -SO 3 -, -SO 2 N - SO 2 R h, -RCOO -, -RSO 3 - or -RSO 2 N - SO 2 R f ;
  • R and R 2 are each independently a C1-C10 hydrocarbylene group, or a C1-C10 hydrocarbylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P ;
  • R 1 and R 4 are each independently H, F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or containing F, Cl, Br, I, N, O, S, Si, B and P One or more C1-C10 hydrocarbon groups;
  • R 3 , R h and R f are each independently F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or containing F, Cl, Br, I, N, O, S, Si, B and P One or more of C1-C10 hydrocarbon groups;
  • Y is N or P, p is 3; or, Y is S, p is 2;
  • l and m are the same or different positive integers.
  • l:m 1:(0.5 ⁇ 1.5).
  • R 2 is a C1-C4 alkylene group, or a C1-C4 alkylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B and P
  • R 3 is -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) s CH 3 , s is 1 ⁇ 8
  • R 1 and R 4 are each independently H, -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) v CH 3 , v is 1 ⁇ 8.
  • the polymer ionic liquid may further include a structural unit represented by formula III;
  • R 5 is a C1-C10 alkylene group, or a C1-C10 alkylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P, optionally -(CH 2 ) t -or -(CH 2 ) q -O-(CH 2 ) r -, t is 1-8, q is 0-4, r is 0-4, q and r are not both 0;
  • R 6 is H, F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or contains one or more of F, Cl, Br, I, N, O, S, Si, B and P
  • the C1 ⁇ C10 hydrocarbon group optionally H, -CN, -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) u CH 3 , u is 1 ⁇ 8;
  • n is a positive integer.
  • l:m:n 1:(0.5 ⁇ 1.5):(0 ⁇ 1.5).
  • the functionalized isolation membrane contains a suitable polymer ionic liquid, which can further improve the first coulombic efficiency, cycle performance and safety performance of lithium metal batteries.
  • the number average molecular weight of the polymer ionic liquid is 40,000 to 1,000,000.
  • the mass ratio of the inorganic particles to the polymer ionic liquid is (80-99): (1-20), optionally (90-98): (2 ⁇ 10).
  • the use of this functional film can further improve the cycle performance and first-time coulombic efficiency of the battery.
  • the thickness of the functional film layer is 0.1 ⁇ m to 20 ⁇ m, and optionally 1 ⁇ m to 10 ⁇ m.
  • the thickness of the functional film layer is within an appropriate range, which is beneficial for the battery to take into account the high first-time coulombic efficiency, cycle performance and safety performance at the same time.
  • the substrate is a polymer substrate.
  • the polymer substrate can have both higher strength and toughness, so that the functionalized separator has higher strength and toughness, which is beneficial to improve the cycle performance of the battery.
  • the thickness of the substrate is 5 ⁇ m-25 ⁇ m.
  • the second aspect of the present application provides a method for preparing a functionalized isolation film, which includes the step of forming a functional film layer containing inorganic particles on at least one surface of a porous substrate, wherein the inorganic particles can reversibly react with metallic lithium to form Lithium alloy.
  • a third aspect of the present application provides a lithium metal battery, which includes: a positive electrode sheet; a negative electrode sheet including a lithium-based metal layer; and an isolation film.
  • the isolation film adopts the functionalized isolation film of the first aspect of the application, and the functional film layer Arranged in contact with the lithium-based metal layer; and electrolyte.
  • the functionalized separator of the present application can also be used in lithium ion secondary batteries other than lithium metal batteries, such as lithium ion secondary batteries with graphite negative electrodes, lithium ion secondary batteries with silicon-based negative electrodes, and the like.
  • the functional film layer of the functionalized separator is arranged close to or in contact with the negative electrode film layer.
  • the inorganic particles in the functionalized separator react reversibly with lithium ions to form a lithium alloy, which can regulate the diffusion behavior of lithium ions in the negative electrode, and is beneficial to uniform lithium insertion in the negative electrode, effectively inhibiting the surface of the negative electrode. Crystal growth.
  • a fourth aspect of the present application provides a device, which includes the lithium metal battery described in the second aspect of the present application.
  • the device of the present application includes the lithium metal battery, and thus can have the same or similar beneficial effects.
  • FIG. 1 is a schematic structural diagram of a functional isolation membrane according to an embodiment of the application.
  • Fig. 2 is a partial enlarged schematic diagram of the functional film layer in Fig. 1.
  • FIG. 3 is a schematic structural diagram of an embodiment of a lithium metal battery.
  • Fig. 4 is an exploded view of Fig. 3.
  • Fig. 5 is a schematic diagram of an embodiment of a battery module.
  • Fig. 6 is a schematic diagram of an embodiment of a battery pack.
  • Fig. 7 is an exploded view of Fig. 6.
  • FIG. 8 is a schematic diagram of an embodiment of a device in which a lithium metal battery is used as a power source.
  • any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and any upper limit may be combined with any other upper limit to form an unspecified range.
  • every point or single value between the end points of the range is included in the range. Therefore, each point or single numerical value can be used as its own lower limit or upper limit in combination with any other point or single numerical value or in combination with other lower or upper limits to form an unspecified range.
  • the embodiment of the first aspect of the present application provides a functional isolation membrane.
  • the functionalized isolation film includes a porous substrate and a functional film layer laminated on at least one side of the porous substrate; wherein the functional film layer includes inorganic particles, which can reversibly react with metallic lithium to form a lithium alloy.
  • the functionalized separator When the functionalized separator is used in a lithium metal battery and the functional film layer is in contact with lithium metal, under the action of the electrolyte, the inorganic particles and the metal lithium react reversibly to form a lithium alloy in situ (can be used as a negative electrode active material for lithium ion batteries) , Changed the lithium composition of the metal lithium electrode surface.
  • the formation of the lithium alloy effectively improves the surface properties of the metal lithium electrode, can regulate the deposition/dissolution behavior of lithium ions, and effectively inhibit the formation of lithium dendrites.
  • the formation of lithium dendrites is effectively suppressed, it can effectively solve the continuous reorganization of the SEI (solid electrolyte interphase) film on the surface of the metal lithium electrode caused by the growth of lithium dendrites in the existing lithium metal batteries and the continuous reorganization of the electrolyte and active lithium
  • the problem of consumption improves the reversibility of the lithium ion deposition/dissolution process in the lithium metal electrode, thereby improving the capacity performance of the battery and extending the cycle life of the battery.
  • the use of the functionalized isolation film of the present application also avoids the problem of short circuit in the battery caused by the lithium dendrites piercing the isolation film, and improves the safety performance of the battery.
  • the use of the functionalized isolation membrane of the present application can improve the first-time coulombic efficiency, cycle performance and safety performance of the lithium metal battery.
  • Lithium can form intermetallic compounds with many materials, and the reaction to form lithium alloys is a reversible reaction, so lithium ions can be inserted and extracted.
  • the inorganic particles can be selected from materials capable of forming a lithium alloy with lithium.
  • the inorganic particles are selected from one or more of silicon, silicon-oxygen compound SiO a , magnesium, aluminum, zinc, indium, antimony, silver, gold, germanium and tin, wherein 0 ⁇ a ⁇ 2, such as 0.9 ⁇ a ⁇ 1.2.
  • the volume average particle diameter D v 50 of the inorganic particles is 10 nm to 20 ⁇ m.
  • D v 50 is 50 nm to 10 ⁇ m.
  • D v 50 is 200 nm to 2 ⁇ m.
  • the inorganic particles have an appropriate particle size, and the inorganic particles alloyed with lithium have high structural stability, and are unlikely to crack or break during the battery cycle, thereby improving the cycle performance of the battery.
  • the inorganic particles have an appropriate particle size, and the migration path of lithium ions in the alloyed inorganic particles is short, which can increase the ionic conductivity of the functional film layer, thereby improving the battery capacity and cycle performance.
  • At least part of the surface of the inorganic particles may also be coated with a polymer coating layer.
  • the polymer coating layer protects the lithium alloy, can inhibit the volume change of the lithium alloy during the charging and discharging of the battery, and prevent the structural damage of the lithium alloy due to the larger volume expansion effect.
  • the polymer coating can also reduce the side reaction of the interface between the lithium metal and the electrolyte, reduce battery impedance and reduce battery gas.
  • the functional film layer helps to improve the cycle performance of the battery.
  • the polymer coating layer generally has good bonding properties, and can achieve a strong bond between the functional film layer and the porous substrate, so that the functional film layer can be used or not used as a binder according to requirements.
  • the polymer coating layer covering the surface of the inorganic particles can be, but not limited to, one or more selected from polyvinylidene fluoride (PVDF), polyacrylic acid (PAA), polyaniline, polyolefin, and polyamide.
  • PVDF polyvinylidene fluoride
  • PAA polyacrylic acid
  • polyaniline polyaniline
  • polyolefin polyamide
  • polyamide polyamide
  • the polymer coating layer contains groups capable of reversibly bonding with lithium ions.
  • the group reacts in situ with the lithium alloy (such as ion exchange; another example is that the chemical bond in the group (such as the SS bond in the polysulfide group) can be broken and combined with the lithium ion. After the lithium ion is removed, the chemical bond can be Re-bonding) to form a reversible bond between the group and the lithium ion.
  • the bonding fastness between the coating layer and the inorganic particles is enhanced, and the coating layer can more effectively suppress the volume change of the lithium alloy during the charge and discharge of the battery.
  • the protective effect of the coating layer can effectively exert the above-mentioned effects of the inorganic particles, thereby better suppressing the generation of lithium dendrites and suppressing the increase of the interface impedance of the lithium metal electrode.
  • the chemical bond formed in situ between the group of the coating layer and the lithium ion can also serve as a channel for lithium ion transfer, which can promote the transfer of lithium ion and improve the dynamic performance in the lithium alloy electrode.
  • the use of the functional isolation membrane can further improve the first-time coulombic efficiency, cycle performance and safety performance of lithium metal batteries.
  • groups capable of reversibly bonding with lithium ions include, for example, acid groups, amino groups (-NH 2 ), imino groups (-NH), and mercapto groups (-SH ) And polysulfide groups (-S b -, b ⁇ 2), but not limited to one or more.
  • Optional is an acid group.
  • the acid radicals can more effectively react with the lithium alloy in situ, so that the coating layer and the surface of the lithium alloyed inorganic particles have a stronger force, which can further alleviate the volume change of the lithium alloy.
  • the organic acid lithium formed in situ by the organic acid group and the lithium alloy can better promote the migration of lithium ions and improve the lithium ion conductivity of the functional film layer.
  • the acid radical group may include a carboxylic acid group (-COOH), a sulfonic acid group (-SO 3 H), a sulfinic acid group (-SO 2 H), and a phosphoric acid group (-H 2 PO 4 ).
  • the acid group includes one or more of a carboxylic acid group and a sulfonic acid group.
  • the acid group includes a carboxylic acid group.
  • the polymer of the coating layer is polyolefin.
  • the polymer is polyolefins containing acid radicals, that is, polyolefinic acid.
  • Polyenoic acid has high bonding performance, and after it reacts with lithium alloy in situ, it can coat the surface of inorganic particles more firmly, thereby better suppressing the volume of lithium alloy during battery charging and discharging. Variety.
  • the chemical bond formed by the acid functional group of the polyenoic acid and lithium can further improve the lithium ion conductivity of the functional film.
  • the polyenoic acid may include, but is not limited to, polyethylene containing acid radicals, polypropylene containing acid radicals, polyisobutylene containing acid radicals, polynorbornene containing acid radicals, Acid group-containing polymethylpentene, acid group-containing polyisoprene, acid group-containing poly(1,4-butadiene), acid group-containing poly(1,2-butadiene) (Ene)-styrene (co)polymer, acid group-containing polystyrene, acid group-containing poly(methylstyrene), acid group-containing poly( ⁇ , ⁇ , ⁇ -trifluorostyrene) ), one or more of poly(pentafluorostyrene)-perfluoroionomers containing acid radicals.
  • the polyolefin acid can be selected from one of polymethacrylic acid, polyacrylic acid, polyvinylbenzenesulfonic acid, polypropylene-polyvinylbenzenesulfonic acid, polyvinylsulfonic acid, polypropylenesulfonic acid, and polystyrene phosphoric acid.
  • the polyolefin acid can be selected from one or more of polyacrylic acid and polyvinylbenzenesulfonic acid.
  • the thickness of the cladding layer may be 1 nm to 1 ⁇ m, 5 nm to 200 nm, and 20 nm to 100 nm.
  • the thickness of the coating layer is suitable for suppressing the volume change of the lithium alloy, and at the same time, the functional film layer has a higher lithium ion conductivity, thereby improving the first-time coulombic efficiency and cycle performance of the battery.
  • the functional film layer may also include a polymer ionic liquid.
  • the groups that reversibly bond with lithium ions in the polymer coating layer are electronegative.
  • the polymer ionic liquid contains positively charged groups.
  • the electronegative groups in the coating layer are similar to those in the polymer ionic liquid.
  • the charge groups can interact with each other to physically cross-link the polymer ionic liquid and the polymer coating, which is beneficial to improve the strength and electrolyte resistance of the functional membrane layer, so that the functional membrane layer can better perform the aforementioned The effect of the description.
  • the polymer ionic liquid also contains negatively charged groups, which can enhance the transfer rate of lithium ion positive charges and reduce impedance and overpotential. Therefore, such a functional isolation membrane can further improve the first-time coulombic efficiency, cycle performance and safety performance of lithium metal batteries.
  • the polymer ionic liquid may be a compound containing the structural units shown in Formula I and Formula II.
  • X is a negatively charged anion.
  • X is -COO -, -SO 3 -, -SO 2 N - SO 2 R h, -RCOO -, -RSO 3 - or -RSO 2 N - SO 2 R f .
  • R is a C1-C10 alkylene group, or contains fluorine (F), chlorine (Cl), bromine (Br), iodine (I), nitrogen (N), oxygen (O), sulfur (S), silicon (Si) , C1-C10 alkylene group of one or more of boron (B) and phosphorus (P).
  • R h is F, Cl, Br, I, cyano (-CN), C1-C10 hydrocarbon group, or one of F, Cl, Br, I, N, O, S, Si, B and P or Several C1-C10 hydrocarbon groups.
  • R f is F, Cl, Br, I, cyano (-CN), C1-C10 hydrocarbon group, or one of F, Cl, Br, I, N, O, S, Si, B and P or Several C1-C10 hydrocarbon groups.
  • R 1 is H, F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or contains one or more of F, Cl, Br, I, N, O, S, Si, B and P The C1 ⁇ C10 hydrocarbon group.
  • R 1 is H, -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) v CH 3 , v is 1 ⁇ 8.
  • l is a positive integer.
  • Y is nitrogen (N), sulfur (S) or phosphorus (P), and p is 2 or 3.
  • the value of p is related to the valence of the Y atom.
  • Y is N or P, and p is 3.
  • Y is S and p is 2.
  • R 2 is a C1-C10 hydrocarbylene group, or a C1-C10 hydrocarbylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P.
  • R 2 is a C1-C4 alkylene group, or a C1-C4 alkylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B and P base.
  • R 3 is F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or C1 containing one or more of F, Cl, Br, I, N, O, S, Si, B and P ⁇ C10 hydrocarbon group.
  • R 3 is -CH 3 , -C 2 H 5 , linear-C 3 H 7 , linear-C 4 H 9 or -(CH 2 CH 2 O) s CH 3 , and s is 1 ⁇ 8 . It can be understood that the p R 3 connected to Y may be the same or different.
  • R 4 is H, F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or containing one or more of F, Cl, Br, I, N, O, S, Si, B and P A hydrocarbon group with 1 to 10 carbon atoms.
  • R 4 is H, -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) v CH 3 , v is 1 ⁇ 8.
  • n is a positive integer.
  • l and m are the same or different positive integers.
  • l:m 1:(0.5 ⁇ 1.5).
  • the polymer ionic liquid contains structural units represented by formula I, formula II and formula III.
  • Such polymer ionic liquid can improve the toughness of the functional membrane layer, thereby preventing the functional separator from breaking during electrode assembly processing and battery use, and more effectively exerting the above-mentioned performance of the functional separator.
  • R 5 is a C1-C10 hydrocarbylene group, or a C1-C10 hydrocarbylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P .
  • R 5 is -(CH 2 ) t -or -(CH 2 ) q -O-(CH 2 ) r -, t is 1 to 8, q is 0 to 4, r is 0 to 4, q It is not 0 at the same time as r.
  • R 6 is H, F, Cl, Br, I, -CN, C1-C10 hydrocarbon group, or contains one or more of F, Cl, Br, I, N, O, S, Si, B and P The C1 ⁇ C10 hydrocarbon group.
  • R 6 is H, -CN, -CH 3 , -C 2 H 5 , linear -C 3 H 7 , linear -C 4 H 9 or -(CH 2 CH 2 O) u CH 3 , u is 1-8.
  • n is a positive integer.
  • l:m:n 1:(0.5 ⁇ 1.5):(0 ⁇ 1.5).
  • the polymer ionic liquid may have a linear structure, a branched structure or a cross-linked three-dimensional network structure.
  • the polymer ionic liquid may be a random copolymer or a block copolymer.
  • the number average molecular weight of the polymer ionic liquid may be 40,000 to 1,000,000.
  • the mass ratio of the inorganic particles to the polymer ionic liquid is (80 ⁇ 99):(1 ⁇ 20), optionally (90 ⁇ 98):(2 ⁇ 10) .
  • the functional film layer while the volume change of the lithium alloy is effectively suppressed, it also has high lithium ion migration performance.
  • the thickness of the functional film layer may be 0.1 ⁇ m to 20 ⁇ m, for example, 1 ⁇ m to 10 ⁇ m.
  • the proper thickness of the functional film layer is conducive to inhibiting the generation of lithium dendrites in the lithium metal negative electrode, and at the same time enabling the battery to take into account the high first coulombic efficiency and cycle performance.
  • C1-C10 hydrocarbon group is a group formed by the loss of any hydrogen atom on the molecule of a hydrocarbon compound having a carbon number of 1 or more and 10 or less.
  • C1-C10 hydrocarbon group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P means that the number of carbon atoms is greater than or equal to 1 and less than or equal to 10 and contains F , Cl, Br, I, N, O, S, Si, B, and P one or more of the hydrocarbon compounds lose any hydrogen atom on the molecule.
  • the "C1-C10 hydrocarbylene group” is a group formed by the loss of any two hydrogen atoms in the molecule of a hydrocarbon compound having a carbon number of 1 or more and 10 or less.
  • a C1-C10 hydrocarbylene group containing one or more of F, Cl, Br, I, N, O, S, Si, B, and P means that the number of carbon atoms is greater than or equal to 1 and less than or equal to 10 and contains F , Cl, Br, I, N, O, S, Si, B, and P one or more of the hydrocarbon compounds lose any two hydrogen atoms on the molecule.
  • the hydrocarbon compound may be a saturated hydrocarbon or an unsaturated hydrocarbon, including but not limited to alkanes, cycloalkanes, alkenes, alkynes, and aromatic hydrocarbons.
  • the hydrocarbon compound may have a linear structure or a branched structure.
  • the substrate includes, but is not limited to, one or more selected from ceramic substrates and polymer substrates.
  • the substrate includes but is not limited to one or more of glass fiber, non-woven fabric, polyethylene, polypropylene, and polyvinylidene fluoride.
  • the substrate can be a single-layer film or a multilayer composite film.
  • the materials of each layer may be the same or different.
  • the thickness of the substrate may be 5 ⁇ m to 25 ⁇ m, for example, 8 ⁇ m to 15 ⁇ m, such as 10 ⁇ m.
  • the present application also provides a method for preparing a functionalized isolation film, which includes: providing a porous substrate; and forming a functional film layer containing inorganic particles on at least one surface of the porous substrate, wherein the inorganic particles can interact with metal Lithium undergoes a reversible reaction to form a lithium alloy.
  • a functionalized isolation film including inorganic particles and a polymer coating layer covering at least part of the surface of the inorganic particles can be prepared.
  • a coating method is used to bond inorganic particles to the surface of the substrate through a binder.
  • the binder can be, but is not limited to, selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), sodium carboxymethyl cellulose (CMC), alginic acid One or more of sodium (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the method for preparing the functionalized isolation membrane of the present application includes the following steps:
  • the polymer can be, but is not limited to, selected from any one or several described herein.
  • solvent including but not limited to water, N-Methylpyrrolidone (N-Methylpyrrolidone, abbreviated as NMP), Xylene (Dimethylbenzene, abbreviated as DMB), toluene (Methylbenzene, abbreviated as MB) And dimethylformamide (N, N-Dimethylformamide, abbreviated as DMF) one or more.
  • the mass concentration of the polymer may be 0.1%-10%, and optionally 1%-5%.
  • the inorganic particles can be, but are not limited to, selected from any one or several described herein.
  • the mass ratio of inorganic particles to polymer can be 10-300, optionally 20-200, and optionally 50-100.
  • the proper mass ratio of the inorganic particles to the polymer is beneficial to uniformly coat the surface of the inorganic particles with the polymer and the coating layer has an appropriate thickness.
  • step S20 the inorganic particles are dispersed in the polymer-containing solution and stirred to obtain a uniformly mixed mixed slurry.
  • the stirring can be mechanical stirring or ultrasonic stirring.
  • step S30 equipment and methods known in the art can be used to dry the mixed slurry, such as vacuum drying, airflow drying, spray drying, and the like. Drying can be performed under an inert protective atmosphere, which can be, but is not limited to, one or more selected from nitrogen, argon, and helium.
  • step S30 may be performed by using a spray dryer.
  • the material prepared by the spray drying method has more uniform coating, less agglomeration and higher preparation efficiency.
  • the drying temperature may be 80°C to 300°C, for example, 110°C to 250°C.
  • the heating rate may be 1°C/min-10°C/min, for example, 1°C/min-5°C/min.
  • the solvent can be, but is not limited to, selected from water, N-methylpyrrolidone (N-Methylpyrrolidone, abbreviated as NMP), xylene (Dimethylbenzene, abbreviated as DMB), toluene (Methylbenzene, abbreviated as MB), and dimethylbenzene.
  • NMP N-methylpyrrolidone
  • DMB xylene
  • DMB toluene
  • MB Methylbenzene
  • dimethylbenzene xylene
  • DMF dimethylbenzene
  • DMF N-Dimethylformamide
  • the solid content in the coating slurry can be 20% to 70%, such as 30% to 50%.
  • a polymer ionic liquid is also optionally added.
  • the polymer ionic liquid can be, but is not limited to, selected from any one or several described herein.
  • the polymer ionic liquid can be prepared by a preparation method known in the art. For example, the monomer of the polymer ionic liquid is added to the solvent, and the cross-linking polymerization of the monomer is initiated by heat and/or light to obtain the polymer ionic liquid.
  • step S50 the coating slurry can be uniformly coated on the surface of the porous substrate by using equipment and methods known in the art, such as a micro-gravure coating method, which can make the coating uniformity better.
  • the temperature for drying the coated wet film may be 60°C to 120°C, such as 70°C to 100°C. Drying can be performed under an inert protective atmosphere, which can be, but is not limited to, one or more selected from nitrogen, argon, and helium.
  • the functionalized isolation membrane includes a porous substrate 1 and a functional film layer 2 laminated on the surface of the porous substrate.
  • the functional film layer 2 includes a polymer ionic liquid 21 and composite particles 22.
  • the composite particle 22 includes an inorganic particle 221 and a polymer coating layer 222 covering the entire surface of the inorganic particle 221.
  • the embodiment of the application also provides a lithium metal battery.
  • the lithium metal battery includes a positive electrode sheet, a negative electrode sheet, a separator and an electrolyte.
  • the negative electrode sheet includes a negative electrode current collector and a lithium-based metal layer laminated on at least one surface of the negative electrode current collector.
  • the lithium-based metal layer may be selected from a lithium alloy layer or a metallic lithium layer.
  • the isolation film adopts any one of the functional isolation films of the first aspect of the present application, and the functional film layer is arranged in contact with the lithium-based metal layer.
  • the inorganic particles and the metal lithium react reversibly to form a lithium alloy in situ, thereby changing the lithium composition on the surface of the lithium-based metal layer.
  • the formation of lithium alloys can control the behavior of lithium ion deposition/dissolution, effectively inhibit the growth of lithium metal electrode dendrites, and help improve the reversibility of the lithium ion deposition/dissolution process in the lithium metal negative electrode. Therefore, the lithium metal battery of the present application can simultaneously take into account higher first-time coulombic efficiency, cycle performance and safety performance.
  • the negative electrode current collector can be made of materials with good electrical conductivity and mechanical strength, such as copper foil.
  • the negative electrode sheet can be prepared according to conventional methods in the art. For example, a lithium-based metal sheet is attached to the surface of a copper foil to obtain a negative electrode sheet.
  • the bonding can be achieved by but not limited to roller pressing.
  • the positive electrode sheet includes a positive electrode current collector and a positive electrode film layer laminated on at least one surface of the positive electrode current collector and including a positive electrode active material.
  • the positive electrode current collector can be made of materials with good conductivity and mechanical strength, such as aluminum foil.
  • the specific type of the positive electrode active material is not specifically limited.
  • Well-known materials that can be used as the positive electrode active material of the lithium metal battery can be used, and those skilled in the art can choose according to actual needs.
  • the positive electrode active material may be, but is not limited to, selected from lithium transition metal oxides and modified materials thereof.
  • the modified material includes one of a coated modified material, a doped modified material, and a coated and doped modified material Or several.
  • the transition metal can be one or more of Mn, Fe, Ni, Co, Cr, Ti, Zn, V, Al, Zr, Ce, and Mg.
  • the positive electrode active material can be, but is not limited to, selected from lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, and olivine structure One or more of the lithium-containing phosphate and its modified materials.
  • the positive electrode film layer may also include a binder and/or a conductive agent.
  • the types of the binder and the conductive agent are not specifically limited, and those skilled in the art can make selections according to actual needs.
  • the binder used for the positive electrode film layer can be, but is not limited to, selected from polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), carboxymethyl One or more of sodium cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMAA) and carboxymethyl chitosan (CMCS).
  • the conductive agent used for the positive electrode film layer can be, but is not limited to, one or more selected from graphite, superconducting carbon, acetylene black, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphene, and carbon nanofibers .
  • the positive electrode sheet can be prepared according to conventional methods in the art.
  • the positive electrode active material and optional conductive agent and binder are dispersed in a solvent (such as N-methylpyrrolidone, referred to as NMP) to form a uniform positive electrode slurry, and the positive electrode slurry is coated on the positive electrode current collector After drying, cold pressing and other processes, a positive electrode sheet is obtained.
  • a solvent such as N-methylpyrrolidone, referred to as NMP
  • the positive electrode sheet, the separator film, and the negative electrode sheet can be made into an electrode assembly by a lamination process or a winding process, wherein the separator film is located between the positive electrode sheet and the negative electrode sheet to play a role of isolation.
  • the electrolyte includes electrolyte salt and solvent.
  • the electrolyte salt can be, but is not limited to, selected from LiPF 6 (lithium hexafluorophosphate), LiBF 4 (lithium tetrafluoroborate), LiClO 4 (lithium perchlorate), LiAsF 6 (lithium hexafluoroarsenate), LiFSI (bisfluorosulfonimide) Lithium), LiTFSI (lithium bistrifluoromethanesulfonimide), LiTFS (lithium trifluoromethanesulfonate), LiDFOB (lithium difluorooxalate), LiBOB (lithium bisoxalate), LiPO 2 F 2 (difluoro One or more of lithium phosphate), LiDFOP (lithium difluorodioxalate phosphate) and LiTFOP (lithium tetrafluorooxalate phosphate).
  • LiPF 6 lithium hexafluorophosphate
  • LiBF 4 lithium tetrafluoroborate
  • the solvent used in the electrolyte can be, but is not limited to, selected from ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), dimethyl carbonate (DMC) ), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethylene propyl carbonate (EPC), butylene carbonate (BC), fluoroethylene carbonate (FEC), methyl formate (MF), Methyl acetate (MA), ethyl acetate (EA), propyl acetate (PA), methyl propionate (MP), ethyl propionate (EP), propyl propionate (PP), methyl butyrate ( MB), ethyl butyrate (EB), 1,4-butyrolactone (GBL), sulfolane (SF), dimethyl sulfone (MSM), methyl ethyl sulfone (EMS) and dieth
  • the electrolyte may also optionally include additives, where there is no specific restriction on the type of additives, and can be selected according to requirements.
  • the additives can be, but are not limited to, selected from vinylene carbonate (VC), vinyl ethylene carbonate (VEC), fluoroethylene carbonate (FEC), succinonitrile (SN), adiponitrile (ADN)
  • VC vinylene carbonate
  • VEC vinyl ethylene carbonate
  • FEC fluoroethylene carbonate
  • SN succinonitrile
  • ADN adiponitrile
  • PST 1,3-propene sultone
  • TMSP tris(trimethylsilane) phosphate
  • TMSB tris(trimethylsilane) borate
  • the lithium metal battery also includes an outer packaging for packaging the electrode assembly and electrolyte (not shown).
  • the outer packaging of the lithium metal battery may be a hard shell, such as a hard plastic shell, aluminum shell, steel shell, and the like.
  • the outer packaging of the lithium metal battery can also be a soft bag, such as a soft bag.
  • the soft package can be aluminum-plastic film packaging or plastic film packaging, which can include one or more of polypropylene PP, polybutylene terephthalate PBT, polybutylene succinate PBS, and the like.
  • the lithium metal battery can be prepared by a method known in the art. As an example, stack the positive electrode sheet, the separator film, and the negative electrode sheet in order, so that the separator film is placed between the positive electrode sheet and the negative electrode sheet to isolate the electrode assembly, or the electrode assembly can be obtained after winding; The electrode assembly is placed in a packaging shell, electrolyte is injected and sealed to obtain a lithium metal battery.
  • Fig. 3 shows a lithium metal battery 5 with a square structure as an example.
  • the outer package may include a housing 51 and a cover 53.
  • the housing 51 may include a bottom plate and a side plate connected to the bottom plate, and the bottom plate and the side plate enclose a receiving cavity.
  • the housing 51 has an opening communicating with the containing cavity, and a cover plate 53 can cover the opening to close the containing cavity.
  • the electrode assembly 52 is packaged in the receiving cavity.
  • the number of electrode assemblies 52 contained in the lithium metal battery 5 can be one or several, which can be adjusted according to requirements.
  • the lithium metal battery can be assembled into a battery module, and the number of lithium metal batteries contained in the battery module can be multiple, and the specific number can be adjusted according to the application and capacity of the battery module.
  • FIG. 5 is a battery module 20 as an example.
  • a plurality of lithium metal batteries 5 may be arranged in sequence along the length direction of the battery module 20. Of course, it can also be arranged in any other manner. Furthermore, the plurality of lithium metal batteries 5 can be fixed by fasteners.
  • the battery module 20 may further include a housing having an accommodation space, and a plurality of lithium metal batteries 5 are accommodated in the accommodation space.
  • the above-mentioned battery modules can also be assembled into a battery pack, and the number of battery modules contained in the battery pack can be adjusted according to the application and capacity of the battery pack.
  • the battery pack 30 may include a battery box and a plurality of battery modules 20 provided in the battery box.
  • the battery box includes an upper box body 31 and a lower box body 32.
  • the upper box body 31 can be covered on the lower box body 32 to form a closed space for accommodating the battery module 20.
  • a plurality of battery modules 20 may be arranged in the battery box in any manner.
  • the application also provides a device including the lithium metal battery of the application.
  • the lithium metal battery can be used as the power source of the device, and can also be used as the energy storage unit of the device.
  • the devices are, for example, new energy vehicles, electronic devices, power tools, power storage facilities, and so on.
  • the device may be, but not limited to, mobile devices (such as mobile phones, laptop computers, etc.), electric vehicles (such as pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, Electric golf carts, electric trucks, etc.), electric trains, ships and satellites, energy storage systems, etc.
  • the device can select a lithium metal battery, battery module or battery pack according to its usage requirements.
  • Fig. 8 is a device as an example.
  • the electrical equipment is a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle.
  • a battery pack or battery module can be used.
  • SiO silicon-oxygen compound SiO
  • D v 50 1 ⁇ m
  • a polyacrylic acid aqueous solution with a mass concentration of 1.5% thoroughly mixed and stirred for 5 hours, dried with a spray dryer at a drying temperature of 130°C to obtain composite particles It includes SiO particles and a polyacrylic acid coating layer covering the surface of the SiO particles, and the thickness of the coating layer is 10 nm.
  • the monomer (p-vinylbenzenesulfonyl)(fluorosulfonyl)imide lithium and (butene)(trimethyl)ammonium iodide are mixed in acetone at a molar ratio of 1:1, and 4wt% of p-phenylenediene is added And 2wt% of 2-ethoxy-1,2-diphenylethanone, after ultrasonic dissolution, UV light is used to initiate cross-linking polymerization to obtain polymer ionic liquid IV.
  • the number average molecular weight of the polymer ionic liquid IV is about 100,000, and the polymer ionic liquid IV contains a structural unit represented by formula IV, wherein l and m are about 240 respectively.
  • the composite particles and the polymer ionic liquid with a mass ratio of 95:5 are added to the solvent NMP and mixed uniformly to obtain a coating slurry.
  • the solid content of the coating slurry is 40 wt%.
  • the slurry was uniformly coated on one surface of a 10 ⁇ m thick porous polyethylene substrate by the micro-gravure coating method to obtain a wet film. After the wet film was dried in an oven at 70° C., a functionalized isolation film was obtained. Among them, the thickness of the functional film layer is 5 ⁇ m.
  • the positive electrode active material LiNi 0.8 Co 0.1 Mn 0.1 O 2 , the conductive agent acetylene black, and the binder PVDF are mixed in a mass ratio of 96:2:2, and the solvent NMP is added and stirred until the system is uniform to obtain a positive electrode slurry;
  • the slurry was uniformly coated on the aluminum foil of the positive electrode current collector with a thickness of 12 ⁇ m, and then baked at 120° C. for 1 h, and then successively compacted and slit to obtain a positive electrode sheet.
  • a 25 ⁇ m-thick metal lithium foil was laminated to the surface of an 8 ⁇ m-thick copper foil by roll pressing and sliced to obtain a negative electrode sheet.
  • EC ethylene carbonate
  • PC propylene carbonate
  • DEC diethyl carbonate
  • the positive electrode sheet, the separator film, and the negative electrode sheet are laminated in sequence to prepare the electrode assembly, the functional film layer of the separator film and the lithium-based metal layer of the negative electrode sheet are bonded together, and then packed into an aluminum foil packaging bag, and then the electrolyte is poured in order and packaged to obtain Lithium metal battery with a capacity of 1Ah.
  • the preparation of the lithium metal battery is the same as that of Example 1, except that the particle size of the inorganic particles in the composite particles is 10 nm.
  • the preparation of the lithium metal battery is the same as that of Example 1, except that the particle size of the inorganic particles in the composite particles is 200 nm.
  • the preparation of the lithium metal battery is the same as that of Example 1, except that the particle size of the inorganic particles in the composite particles is 2 ⁇ m.
  • the preparation of the lithium metal battery is the same as that of Example 1, except that the particle size of the inorganic particles in the composite particles is 20 ⁇ m.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the thickness of the polyacrylic acid coating layer in the composite particles is 1 nm.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the thickness of the polyacrylic acid coating layer in the composite particles is 20 nm.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the thickness of the polyacrylic acid coating layer in the composite particles is 100 nm.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the thickness of the polyacrylic acid coating layer in the composite particles is 1 ⁇ m.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the thickness of the functional film layer is 1 ⁇ m.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the thickness of the functional film layer is 10 ⁇ m.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the thickness of the functional film layer is 20 ⁇ m.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the inorganic particles are elemental silicon.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the inorganic particles are aluminum.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the inorganic particles are tin.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the polymer ionic liquid V is used, which contains the structural unit represented by formula V.
  • polymer ionic liquid V the monomer (p-vinylbenzenesulfonyl) (fluorosulfonyl) imide lithium, iodide (p-vinylbenzyl) (methoxyethyl) ammonium, acrylonitrile by mole 1:1:1.2 is mixed in acetone, 4wt% of p-phenylenediene and 2wt% of 2-ethoxy-1,2-diphenylethanone are added, after ultrasonic dissolution, UV light is used to initiate cross-linking polymerization, The polymer ionic liquid V is obtained.
  • the number average molecular weight of polymer ionic liquid V is about 70,000, l and n are about 110, and m is about 130.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the polymer ionic liquid VI is used, which contains the structural unit represented by formula VI.
  • polymer ionic liquid VI monomer lithium p-vinylbenzenesulfonate, iodide (butene) (trimethyl)phosphonium, and ethylene oxide were mixed in acetone at a molar ratio of 1:1:1.2, and 4wt was added % Of p-phenylenediene and 2wt% of 2-ethoxy-1,2-diphenylethanone were dissolved by ultrasound, and then UV light was used to initiate cross-linking polymerization to obtain polymer ionic liquid VI.
  • the number average molecular weight of the polymer ionic liquid VI is about 60,000, l and n are about 130, and m is about 150.
  • the preparation process of the lithium metal battery is the same as that of Example 1, except that the coating layer is a polyvinylbenzenesulfonic acid coating layer.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the inorganic particles are not coated.
  • the preparation process of the lithium metal battery is the same as in Example 1, the difference lies in: no polymer ionic liquid is added, the inorganic particles are not coated, and the inorganic particles are bonded to the surface of the substrate through the binder PVDF, and the molecular weight of PVDF is 100,000.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that no polymer ionic liquid is added.
  • the preparation process of the lithium metal battery is the same as that in Example 1, except that the isolation membrane is not processed.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that: the surface of the isolation membrane is only coated with polymer ionic liquid IV, and the coating thickness is 5 ⁇ m.
  • the preparation process of the lithium metal battery is the same as in Example 1, except that the inorganic particles are SiO 2 , and the inorganic particles have not been coated.
  • First Coulomb efficiency first week discharge specific capacity (C d1 ) / first week charge specific capacity (C c1 )
  • Capacity retention rate specific discharge capacity after n cycles (C dn ) / specific discharge capacity in the first week (C d1 )
  • the thickness increase ratio is less than 150%, which can be considered as no lithium dendrites; slight: the thickness increase ratio is within 150% to 200%; medium: the thickness increase ratio is within> 200% to 250%; severe: the thickness The growth rate is greater than 250%.
  • the laser diffraction method was used to test the particle size distribution D v 50 (Malvern Laser Particle Sizer 300).
  • PAA means polyacrylic acid
  • PSS means polyvinylbenzenesulfonic acid
  • the interface film formed on the surface of the lithium metal negative plate is thin and dense, while the surface of the lithium metal negative plate of Comparative Example 1 is covered Thick, fluffy brown deposits, and the deposits contain a large amount of lithium dendrites.
  • the large number of lithium dendrites on the surface of the metal lithium negative plate is the main reason for the short circuit of the battery.
  • the lithium dendrites have large surface area and high activity, and are easy to interact with
  • the violent reaction of the electrolyte causes the continuous reorganization of the SEI film on the metal lithium surface, consumes the electrolyte and active lithium, reduces the first coulombic efficiency and cycle efficiency, reduces the battery capacity, and shortens the battery cycle life.
  • This result shows that the use of the functionalized isolation membrane of the present application can effectively improve the cycle performance of the battery and inhibit lithium dendrites.
  • Examples 1, 13-15 and Comparative Example 3 show that when the inorganic particles are SiO, Si, Al, Sn, etc. that can be alloyed with lithium, the lithium composition on the surface of the lithium metal negative electrode can be changed, and the formation energy of the lithium alloy Regulating the behavior of lithium deposition/dissolution and inhibiting the growth of dendrites of the lithium metal electrode is beneficial to improve the reversibility of the lithium deposition/dissolution process, and the battery exhibits good cycle performance.
  • inactive inorganic particles such as SiO 2 are used, the dendrites of the lithium metal negative electrode of the battery are severe, and the battery capacity decays quickly.
  • Examples 1 to 5 show that the particle size of the inorganic particles has a greater impact on the performance of the battery.
  • the particle size is small, there are many pores in the coating, which makes the physical consumption of the electrolyte too large, resulting in accelerated battery degradation.
  • the particle size is too large, the coating uniformity will be poor, resulting in inconsistent effects of the coating on the lithium metal surface.
  • the polymer coating layer and its thickness affect the performance of the battery. Specifically, if there is no coating layer (Example 19) or the coating layer is thin (Example 6), the capacity of the battery decays faster, and the cycle life is correspondingly lower.
  • the polyacrylic acid coating layer can micro-react with the lithium alloy in situ after the lithium alloying, strengthen the force between the lithium alloy and the lithium alloy, which is beneficial to suppress the volume change of the lithium alloy during the charging and discharging process of the battery, and
  • the organic acid lithium structure formed by the in-situ chemical reaction can form a lithium ion transmission channel and promote the transfer of lithium ions.
  • the appropriate thickness of the polymer coating layer can improve the first-time coulombic efficiency and cycle performance of the battery.
  • the thickness of the functional film layer is too thin is not conducive to the formation of a stable alloyed layer, while the thickness of the functional film layer is too thick, which affects the transfer of lithium ions, resulting in a gradual increase in polarization during battery cycles. Larger, faster capacity attenuation.
  • the functional film layer with moderate thickness can effectively inhibit the contact between the electrolyte and the lithium metal, reduce side reactions, and improve the cycle performance of the battery.
  • the type of polymer in the functional film layer also has a significant influence.
  • the negatively charged group structure can enhance the rapid transfer of lithium ion positive charge, reduce impedance and overpotential. Therefore, the addition of polymer ionic liquid to the functional film layer can more effectively improve the lithium dendritic problem of lithium metal batteries, and at the same time, the first coulombic efficiency and cycle performance of the battery are also significantly improved.
  • a protective layer similar to the SEI film can be constructed on the surface of the lithium metal negative electrode, which can suppress the dendritic problem of the lithium metal electrode and reduce the interface between the lithium metal and the electrolyte. Reaction to improve the performance of lithium metal batteries.

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Abstract

本申请公开了一种功能化隔离膜、其制备方法、锂金属电池和包含锂金属电池的装置，功能化隔离膜包括多孔基材以及设置于多孔基材至少一侧的功能膜层；功能膜层包含无机粒子，无机粒子能与金属锂发生可逆反应形成锂合金。

Description

功能化隔离膜、其制备方法、锂金属电池和包含锂金属电池的装置
相关申请的交叉引用
本申请要求享有于2019年07月26日提交的名称为“功能化隔离膜及锂金属电池”的中国专利申请201910682442.1的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请属于储能装置技术领域，具体涉及一种功能化隔离膜及锂金属电池。
背景技术
金属锂的理论比容量(3860mAh/g)远高于当前广泛应用的石墨负极材料的理论比容量(372mAh/g)，且金属锂的电极电位低至-3.04V(vs.H 2/H +)。因此，以金属锂作为负极材料的锂金属电池有望成为下一代高能量密度储能装置。然而，锂金属电池在充电过程中容易产生锂枝晶，这不仅会降低电池的库伦效率及循环寿命，甚至会造成锂枝晶穿透隔离膜引发正负极发生内短路，引起电池爆炸、起火等安全事故。锂枝晶问题严重阻碍了锂金属电池的商业化应用。
发明内容
本申请第一方面提供一种功能化隔离膜，其包括多孔基材以及设置于多孔基材至少一侧的功能膜层；其中，所述功能膜层包含无机粒子，无机粒子能与金属锂发生可逆反应形成锂合金。
本申请提供的功能化隔离膜包括功能膜层，功能膜层包含无机粒子，无机粒子能与金属锂发生可逆反应形成锂合金。当功能化隔离膜用于锂金属电池且功能膜层与锂金属接触时，在电解液作用下，无机粒子与金属锂发生可逆反应原位形成锂合金，从而改变了金属锂电极表面的锂组成。锂合金的形成能够调控锂离子沉积/溶出的行为，有效抑制锂金属电极枝晶的生长，有利于提高锂金属电极中锂离子沉积/溶出过程的可逆性。由此，采用本申请的功能化隔离膜，能改善锂金属电池的首次库伦效率、循环性能及安全性能。
在任意实施方式中，所述无机粒子的体积平均粒径D v50可以为10nm～20μm，可选的为50nm～10μm，进一步可选的为200nm～2μm。无机粒子具有适当的粒径，能改善电池的容量发挥及循环性能。
在任意实施方式中，所述无机粒子可选自硅、硅氧化合物SiO a、镁、铝、锌、铟、锑、银、金、锗及锡中的一种或几种，其中0＜a＜2。
在任意实施方式中，所述无机粒子的至少部分表面包覆有聚合物包覆层，所述包覆层含有与锂离子进行可逆键合的基团。
本申请还可以在无机粒子的至少部分表面包覆有聚合物包覆层，包覆层中含有与锂离子进行可逆键合的基团。该基团与锂合金发生原位反应，进行其与锂离子的可逆键合，提高了包覆层与无机粒子的结合牢度。由此，包覆层能更好地抑制锂合金在电池充放电过程中的体积变化。并且，包覆层的基团与锂离子原位形成的化学键还可以作为锂离子传递的通道，能促进锂离子的传递，改善金属锂电极中的动力学性能。因此该功能化隔离膜能进一步提高锂金属电池的首次库伦效率、循环性能及安全性能。
可选的，所述与锂离子进行可逆键合的基团包括酸根基团、氨基、亚氨基、巯基及多硫基团(-S b-，b≥2)中的一种或几种。进一步可选的，所述酸根基团包括羧酸基团、磺酸基团、亚磺酸基团及磷酸基团中的一种或几种。
在任意实施方式中，所述包覆层包括含有所述酸根基团的聚烯酸。可选的，所述聚烯酸包括聚丙烯酸及聚乙烯苯磺酸中的一种或几种。
无机粒子表面包覆合适的包覆层，能进一步提高电池的循环性能、首次库伦效率及安全性能。
在任意实施方式中，所述包覆层的厚度为1nm～1μm，可选的为5nm～200nm，进一步可选的为20nm～100nm。包覆层具有适当的厚度，可以提升电池的首次库伦效率及循环性能。
在任意实施方式中，所述功能膜层还包括聚合物离子液体。
本申请的功能化隔离膜中，功能膜层还可以包括聚合物离子液体。聚合物离子液体的结构中含有正电荷基团和负电荷基团。正电荷基团能和聚合物包覆层的与锂离子进行可逆键合的基团相互作用，使聚合物离子液体与包覆层的聚合物进行物理交联，从而提高功能膜层的强度和耐电解液性。负电荷基团有利于加强锂离子正电荷的传递速率，降低阻抗和过电位。因此，该功能化隔离膜能进一步提高锂金属电池的首次库伦效率、循环性能及安全性能。
在任意实施方式中，所述聚合物离子液体包含式I和式II所示的结构单元；
Figure PCTCN2020101668-appb-000001
其中，
X为带负电荷的阴离子，可选的为-COO －、-SO 3 －、-SO 2N －SO 2R h、-RCOO －、-RSO 3 －或-RSO 2N －SO 2R f；
R和R 2各自独立地为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基；
R 1和R 4各自独立地为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基；
R 3、R h和R f各自独立地为F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基；
Y为N或P，p为3；或者，Y为S，p为2；
l和m为相同或不同的正整数。
可选的，1≤l≤2500、1≤m≤2500。
可选的，l:m＝1:(0.5～1.5)。
可选的，R 2为C1～C4的亚烷基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C4的亚烷基；和/或，R 3为-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) sCH 3，s为1～8；和/或，R 1和R 4各自独立地为H、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) vCH 3，v为1～8。
进一步可选的，所述聚合物离子液体还可包含式III所示结构单元；
Figure PCTCN2020101668-appb-000002
其中，
R 5为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种 的C1～C10的亚烃基，可选的为-(CH 2) t-或-(CH 2) q-O-(CH 2) r-，t为1～8，q为0～4，r为0～4，q和r不同时为0；
R 6为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基，可选的为H、-CN、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) uCH 3，u为1～8；
n为正整数。
可选的，1≤n≤2500。
可选的，l:m:n＝1:(0.5～1.5):(0～1.5)。
功能化隔离膜中包含合适的聚合物离子液体，能进一步提高锂金属电池的首次库伦效率、循环性能和安全性能。
在任意实施方式中，所述聚合物离子液体的数均分子量为40000～1000000。
在任意实施方式中，所述功能膜层中，所述无机粒子与所述聚合物离子液体的质量比为(80～99):(1～20)，可选的为(90～98):(2～10)。采用该功能膜层能进一步提高电池的循环性能及首次库伦效率。
在任意实施方式中，所述功能膜层的厚度为0.1μm～20μm，可选的为1μm～10μm。功能膜层的厚度在适当范围内，有利于使电池同时兼顾较高的首次库伦效率、循环性能和安全性能。
在任意实施方式中，所述基材为聚合物基材。聚合物基材可兼具较高的强度和韧性，由此使功能化隔离膜具有较高的强度和韧性，有利于改善电池的循环性能。
可选的，所述基材的厚度为5μm～25μm。
本申请第二方面提供一种功能化隔离膜的制备方法，其包括在多孔基材的至少一个表面形成包含无机粒子的功能膜层的步骤，其中所述无机粒子能与金属锂发生可逆反应形成锂合金。
本申请第三方面提供一种锂金属电池，其包括：正极片；负极片，包括锂基金属层；隔离膜，该隔离膜为采用本申请第一方面的功能化隔离膜，且功能膜层与锂基金属层接触设置；以及电解液。
可以理解的是，本申请的功能化隔离膜还可以用于除锂金属电池以外的锂离子二次电池，例如石墨负极的锂离子二次电池、硅基负极的锂离子二次电池等。在这些二次电池中，功能化隔离膜的功能膜层靠近或接触于负极膜层设置。在二次电池充电过程中，通过功能化隔膜中的无机粒子与锂离子发生可逆反应形成锂合金，可以调控锂离子在负极的扩散行为，并且有利于负极均匀嵌锂，有效抑制负极表面锂枝晶的生长。
本申请第四方面提供一种装置，其包括本申请第二方面所述的锂金属电池。
本申请的装置包括所述的锂金属电池，因而可具有相同或类似的有益效果。
附图说明
为了更清楚地说明本申请实施例的技术方案，下面将对本申请实施例中所需要使用的附图作简单地介绍，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1为本申请实施例一种功能化隔离膜的结构示意图。
图2为图1中功能膜层的局部放大示意图。
图3为锂金属电池的一实施方式的结构示意图。
图4是图3的分解图。
图5是电池模块的一实施方式的示意图。
图6是电池包的一实施方式的示意图。
图7是图6的分解图。
图8是锂金属电池用作电源的装置的一实施方式的示意图。
具体实施方式
为了使本申请的发明目的、技术方案和有益技术效果更加清晰，以下结合具体实施例对本申请进行详细说明。应当理解的是，本说明书中描述的实施例仅仅是为了解释本申请，并非为了限定本申请。
为了简便，本文仅明确地公开了一些数值范围。然而，任意下限可以与任何上限组合形成未明确记载的范围；以及任意下限可以与其它下限组合形成未明确记载的范围，同样任意上限可以与任意其它上限组合形成未明确记载的范围。此外，尽管未明确记载，但是范围端点间的每个点或单个数值都包含在该范围内。因而，每个点或单个数值可以作为自身的下限或上限与任意其它点或单个数值组合或与其它下限或上限组合形成未明确记载的范围。
在本文的描述中，需要说明的是，除非另有说明，“以上”、“以下”为包含本数，“一种或几种”中“几种”的含义是两种以上。
本申请的上述发明内容并不意欲描述本申请中的每个公开的实施方式或每种实现方式。如下描述更具体地举例说明示例性实施方式。在整篇申请中的多处，通过一系列实施例提供了指导，这些实施例可以以各种组合形式使用。在各个实例中，列举仅作为代 表性组，不应解释为穷举。
功能化隔离膜
本申请第一方面的实施例提供一种功能化隔离膜。功能化隔离膜包括多孔基材以及层合设置于多孔基材至少一侧的功能膜层；其中，功能膜层包含无机粒子，无机粒子能与金属锂发生可逆反应形成锂合金。
当功能化隔离膜用于锂金属电池且功能膜层与锂金属接触时，在电解液作用下，无机粒子与金属锂发生可逆反应原位形成锂合金(可作为锂离子电池的负极活性材料)，改变了金属锂电极表面的锂组成。锂合金的形成有效改善了金属锂电极表面性质，能够调控锂离子沉积/溶出的行为，有效抑制锂枝晶的生成。
由于锂枝晶的生成得到有效抑制，能有效解决现有锂金属电池中因锂枝晶生长造成的金属锂电极表面SEI(solid electrolyte interphase，固体电解质界面)膜持续重组及电解液和活性锂持续消耗的问题，提高锂金属电极中锂离子沉积/溶出过程的可逆性，从而能提高电池的容量性能，延长电池的循环寿命。采用本申请的功能化隔离膜，还避免了因锂枝晶刺穿隔离膜而导致的电池内短路问题，提高电池的安全性能。
由此，采用本申请的功能化隔离膜，能改善锂金属电池的首次库伦效率、循环性能及安全性能。
[功能膜层]
锂能与许多材料形成金属间化合物，且生成锂合金的反应为可逆反应，因此能够进行锂离子的嵌入和脱出。本申请实施例的功能化隔离膜中，无机粒子可以任选自能与锂形成锂合金的材料。例如，无机粒子选自硅、硅氧化合物SiO a、镁、铝、锌、铟、锑、银、金、锗及锡中的一种或几种，其中0＜a＜2，例如0.9≤a≤1.2。
在一些实施例中，无机粒子的体积平均粒径D v50为10nm～20μm。可选的，D v50为50nm～10μm。进一步可选的，D v50为200nm～2μm。无机粒子具有适当的粒径，与锂发生合金化后的无机粒子的结构稳定性较高，在电池循环过程中不易发生破裂或破碎，从而能提高电池的循环性能。此外，无机粒子具有适当的粒径，锂离子在合金化后的无机粒子中迁移的路径较短，能提高功能膜层的离子电导率，从而能提高电池的容量发挥及循环性能。
在一些可选的实施例中，还可以在无机粒子的至少部分表面包覆有聚合物包覆层。聚合物包覆层对锂合金起到保护作用，能抑制锂合金在电池充放电过程中的体积变化，防止锂合金因较大的体积膨胀效应而造成的结构破坏。聚合物包覆层还能减少锂金属与电解液之间的界面副反应，降低电池阻抗、减少电池胀气。该功能膜层有利于改善电池 的循环性能。
聚合物包覆层通常具有良好的粘结性能，可实现功能膜层与多孔基材的牢固结合，从而该功能膜层中可根据需求使用或不使用粘结剂。
包覆于无机粒子表面的聚合物包覆层可以但不限于选自聚偏氟乙烯(PVDF)、聚丙烯酸(PAA)、聚苯胺、聚烯烃及聚酰胺中的一种或几种。
在一些可选的实施例中，聚合物包覆层中含有能与锂离子进行可逆键合的基团。该基团与锂合金发生原位反应(例如离子交换；再例如基团中的化学键(如多硫基团中的S-S键)可发生断裂并与锂离子结合，锂离子脱出后所述化学键可重新键合)，形成该基团与锂离子的可逆键合。由此，包覆层与无机粒子的结合牢度得到增强，包覆层能更有效地抑制锂合金在电池充放电过程中的体积变化。通过包覆层的保护作用，能有效地发挥无机粒子的上述效果，从而更好地抑制锂枝晶的生成，并能抑制锂金属电极界面阻抗增大。包覆层的基团与锂离子原位形成的化学键还可以作为锂离子传递的通道，能促进锂离子的传递，改善锂合金电极中的动力学性能。采用该功能化隔离膜能进一步提高锂金属电池的首次库伦效率、循环性能及安全性能。
在功能膜层的聚合物包覆层中，能与锂离子进行可逆键合的基团例如可以列举出，酸根基团、氨基(-NH 2)、亚氨基(-NH)、巯基(-SH)及多硫基团(-S b-，b≥2)中的一种或几种，但不限于此。可选的为酸根基团。酸根基团能更有效地与锂合金发生原位反应，使包覆层与锂合金化的无机粒子表面的作用力更强，从而能进一步缓解锂合金的体积变化。有机酸基团与锂合金原位形成的有机酸锂能更好地促进锂离子的迁移，使功能膜层的锂离子传导性能得到改善。
例如，酸根基团可以包括羧酸基团(-COOH)、磺酸基团(-SO 3H)、亚磺酸基团(-SO 2H)及磷酸基团(-H 2PO 4)中的一种或几种。可选的，酸根基团包括羧酸基团及磺酸基团中的一种或几种。进一步可选的，酸根基团包括羧酸基团。
在一些实施例中，包覆层的聚合物为聚烯烃类。可选的，聚合物为含酸根基团的聚烯烃类，即聚烯酸。聚烯酸具有较高的粘结性能，且其与锂合金发生原位反应后，能更牢固地包覆在无机粒子的表面，从而能更好地抑制锂合金在电池充放电过程中的体积变化。聚烯酸的酸官能团与锂形成的化学键还能更加改善功能膜层的锂离子传导性能。
在一些实施例中，聚烯酸可包括但不限于，含酸根基团的聚乙烯、含酸根基团的聚丙烯、含酸根基团的聚异丁烯、含酸根基团的聚降冰片烯、含酸根基团的聚甲基戊烯、含酸根基团的聚异戊二烯、含酸根基团的聚(1,4-丁二烯)、含酸根基团的聚(1,2-丁二烯)-苯乙烯(共)聚合物、含酸根基团的聚苯乙烯、含酸根基团的聚(甲基苯乙烯)、含酸根基团的 聚(α,β,β-三氟苯乙烯)、含酸根基团的聚(五氟苯乙烯)-全氟离聚物中的一种或几种。
可选的，聚烯酸可选自聚甲基丙烯酸、聚丙烯酸、聚乙烯苯磺酸、聚丙烯-聚乙烯苯磺酸、聚乙烯磺酸、聚丙烯磺酸及聚苯乙烯磷酸中的一种或几种。进一步可选的，聚烯酸可选自聚丙烯酸及聚乙烯苯磺酸中的一种或几种。
在一些实施例中，包覆层的厚度可选为1nm～1μm，还可选为5nm～200nm，进一步可选为20nm～100nm。包覆层的厚度适于抑制锂合金的体积变化的同时，且使功能膜层具有较高的锂离子传导能力，从而能提升电池的首次库伦效率及循环性能。
在一些可选的实施例中，功能膜层还可以包括聚合物离子液体。聚合物包覆层中与锂离子进行可逆键合的基团具有电负性，聚合物离子液体中含有正电荷基团，包覆层中的电负性基团与聚合物离子液体中的正电荷基团之间能够相互作用，使聚合物离子液体与聚合物包覆层进行物理交联，有利于提高功能膜层的强度和耐电解液性，从而使功能膜层更好地发挥前文所述的效果。另外，聚合物离子液体中还含有负电荷基团，负电荷基团能加强锂离子正电荷的传递速率，降低阻抗和过电位。因此，这样的功能化隔离膜能进一步提高锂金属电池的首次库伦效率、循环性能及安全性能。
在一些实施例中，聚合物离子液体可为包含式I和式II所示的结构单元的化合物。
Figure PCTCN2020101668-appb-000003
在式I中，X为带负电荷的阴离子。可选的，X为-COO －、-SO 3 －、-SO 2N －SO 2R h、-RCOO －、-RSO 3 －或-RSO 2N －SO 2R f。R为C1～C10的亚烃基、或含氟(F)、氯(Cl)、溴(Br)、碘(I)、氮(N)、氧(O)、硫(S)、硅(Si)、硼(B)及磷(P)中的一种或几种的C1～C10的亚烃基。R h为F、Cl、Br、I、氰基(-CN)、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基。R f为F、Cl、Br、I、氰基(-CN)、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基。
R 1为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、 Si、B及P中的一种或几种的C1～C10的烃基。可选的，R 1为H、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) vCH 3，v为1～8。
l为正整数。可选的，1≤l≤2500。
在式II中，Y为氮(N)、硫(S)或磷(P)，p为2或3。p的值与Y原子的价态相关。可选的，Y为N或P，p为3。可选的，Y为S，p为2。
R 2为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基。可选的，R 2为C1～C4的亚烷基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C4的亚烷基。
R 3为F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基。可选的，R 3为-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) sCH 3，s为1～8。可以理解的是，与Y连接的p个R 3可以相同或不同。
R 4为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的碳原子数为1～10的烃基。可选的，R 4为H、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) vCH 3，v为1～8。
m为正整数。可选的，1≤m≤2500。
在聚合物离子液体中，l和m为相同或不同的正整数。可选的，l:m＝1:(0.5～1.5)。
在一些可选的实施例中，聚合物离子液体中含有式I、式II和式III所示的结构单元。这样的聚合物离子液体能改善功能膜层的韧性，由此使功能化隔离膜在电极组件加工和电池使用过程中不易发生断裂，更有效地发挥功能化隔离膜的上述性能。
Figure PCTCN2020101668-appb-000004
在式III中，R 5为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基。可选的，R 5为-(CH 2) t-或-(CH 2) q-O-(CH 2) r-，t为1～8，q为0～4，r为0～4，q和r不同时为0。
R 6为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基。可选的，R 6为H、-CN、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) uCH 3，u为1～8。
n为正整数。可选的，1≤n≤2500。
在一些实施例的聚合物离子液体中，可选的，l:m:n＝1:(0.5～1.5):(0～1.5)。采用这样的聚合物离子液体，能使功能膜层在具有较高的强度和韧性的同时，还具有较高的锂离子传导能力。
在本文中，对聚合物离子液体的结构及各结构单元的排列方式没有特别的限制。聚合物离子液体可以为直链结构、带支链的结构或交联的三维网状结构。聚合物离子液体可以为无规共聚物或嵌段共聚物等。
聚合物离子液体的数均分子量可以为40000～1000000。
在一些实施例中，在功能膜层中，无机粒子与聚合物离子液体的质量比为(80～99):(1～20)，可选的为(90～98):(2～10)。在该功能膜层中，锂合金的体积变化得到有效抑制的同时，还具有较高的锂离子迁移性能。
在一些实施例中，功能膜层的厚度可以为0.1μm～20μm，例如1μm～10μm。功能膜层的厚度适当，有利于在抑制锂金属负极产生锂枝晶的同时，使电池同时兼顾较高的首次库伦效率及循环性能。
在本文中，“C1～C10的烃基”是碳原子数大于等于1且小于等于10的烃类化合物分子上失去任一氢原子形成的基团。“含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基”是指碳原子数大于等于1且小于等于10且含有F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的烃类化合物分子上失去任一氢原子形成的基团。“C1～C10的亚烃基”是碳原子数大于等于1且小于等于10的烃类化合物分子上失去任两个氢原子形成的基团。“含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基”是碳原子数大于等于1且小于等于10且含有F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的烃类化合物分子上失去任两个氢原子形成的基团。
所述烃类化合物可为饱和烃或不饱和烃，包含但不限于烷烃、环烷烃、烯烃、炔烃、芳香烃。所述烃类化合物可以为直链结构或支链结构。
[基材]
本申请实施例的功能化隔离膜中，对基材的种类没有特别的限制。可以选用任意公知的具有良好的化学稳定性和机械稳定性的多孔结构薄膜。基材包括但不限于选自陶瓷基材和聚合物基材中的一种或几种。例如，基材包括但不限于玻璃纤维、无纺布、聚乙烯、聚丙烯及聚偏氟乙烯中的一种或几种。
基材可以是单层薄膜，也可以是多层复合薄膜。基材为多层复合薄膜时，各层的材料可以相同或不同。
在一些实施例中，基材的厚度可以为5μm～25μm，例如为8μm～15μm，如10μm。
[制备方法]
本申请还提供一种功能化隔离膜的制备方法，其包括：提供多孔基材；以及在多孔基材的至少一个表面形成包含无机粒子的功能膜层的步骤，其中所述无机粒子能与金属锂发生可逆反应形成锂合金。根据该方法能够制备得到包含无机粒子以及包覆于无机粒子至少部分表面的聚合物包覆层的功能化隔离膜。
可以采用多种方式在基材表面形成含无机粒子的功能膜层，例如气相沉积法、电镀法、化学镀法、涂布法等。例如，采用涂布法，通过粘结剂将无机粒子粘结于基材表面。粘结剂可以但不限于选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸(PAA)、聚乙烯醇(PVA)、羧甲基纤维素钠(CMC)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或几种。
根据具体的实施例，本申请的功能化隔离膜的制备方法包括以下步骤：
S10，提供包含聚合物的溶液。
S20，将无机粒子分散于包含聚合物的溶液中，得到混合浆料。
S30，将混合浆料进行干燥处理，得到固体粉末。
S40，将固体粉末分散于溶剂中，得到涂覆浆料。
S50，将涂覆浆料涂布于多孔基材的表面，经干燥后，得到功能化隔离膜。
在步骤S10，聚合物可以但不限于选自本文所述的任意一种或几种。对溶剂的种类没有特别的限制，包括但不限于，水、N-甲基吡咯烷酮(N-Methyl pyrrolidone，简写为NMP)、二甲苯(Dimethylbenzene，简写为DMB)、甲苯(Methylbenzene，简写为MB)及二甲基甲酰胺(N,N-Dimethylformamide，简写为DMF)中的一种或几种。
在步骤S10，包含聚合物的溶液中，聚合物的质量浓度可以为0.1％～10％，可选的为1％～5％。
在步骤S20，无机粒子可以但不限于选自本文所述的任意一种或几种。无机粒子与聚合物的质量比可以为10～300，可选的为20～200，还可选的为50～100。无机粒子与聚合物的质量比适当，有利于使聚合物均匀包覆在无机粒子的表面，且使包覆层具有适当的厚度。
在步骤S20，将无机粒子分散于包含聚合物的溶液中，并进行搅拌，得到混合均匀的混合浆料。搅拌可以采用机械搅拌或超声搅拌等。
在步骤S30，可以采用本领域已知的设备和方法对混合浆料进行干燥，如真空干燥、气流干燥、喷雾干燥等。干燥可以在惰性保护气氛下进行，惰性保护气氛可以但不限于选自氮气、氩气及氦气中的一种或几种。
作为示例，步骤S30可以采用喷雾干燥机进行。喷雾干燥法制备得到的材料包覆更均匀、团聚更少且制备效率更高。
在步骤S30，干燥的温度可以为80℃～300℃，例如为110℃～250℃。其中，升温速度可以为1℃/min～10℃/min，例如为1℃/min～5℃/min。
在步骤S40，溶剂可以但不限于选自水、N-甲基吡咯烷酮(N-Methyl pyrrolidone，简写为NMP)、二甲苯(Dimethylbenzene，简写为DMB)、甲苯(Methylbenzene，简写为MB)及二甲基甲酰胺(N,N-Dimethylformamide，简写为DMF)中的一种或几种。
涂覆浆料中固含量可以为20％～70％，如30％～50％。
在步骤S40，还可选地加入聚合物离子液体。聚合物离子液体可以但不限于选自本文所述的任意一种或几种。
聚合物离子液体可以采用本领域已知的制备方法制备得到。例如，将聚合物离子液体的单体加入溶剂中，并通过热和/或光引发单体交联聚合，得到聚合物离子液体。
在步骤S50，可以采用本领域已知的设备和方法将涂覆浆料均匀涂布于多孔基材的表面，例如微凹涂布法，可以使涂布均匀性更好。
在步骤S50，对涂布所得湿膜进行干燥的温度可以为60℃～120℃，如70℃～100℃。干燥可以在惰性保护气氛下进行，惰性保护气氛可以但不限于选自氮气、氩气及氦气中的一种或几种。
[功能化隔离膜结构]
作为示例，请参照图1，功能化隔离膜包括多孔基材1以及层合设置于多孔基材表面的功能膜层2。功能膜层2包含聚合物离子液体21和复合粒子22。复合粒子22包含无机粒子221和包覆于无机粒子221整个表面的聚合物包覆层222。
需要说明的是，上述的结构仅为对本申请的一个实施例的功能化隔离膜的说明，而不应理解为对本申请功能化隔离膜的结构的限制。
锂金属电池
本申请实施例还提供一种锂金属电池。锂金属电池包括正极片、负极片、隔离膜及电解液。
锂金属电池中，负极片包括负极集流体及层合设置在负极集流体至少一个表面上的锂基金属层。锂基金属层可以选自锂合金层或金属锂层。
隔离膜采用本申请第一方面的任意一种功能化隔离膜，且功能膜层与锂基金属层接触设置。
电池中注入电解液后，在电解液的作用下，无机粒子与金属锂发生可逆反应原位形 成锂合金，从而改变了锂基金属层表面的锂组成。锂合金的形成能够调控锂离子沉积/溶出的行为，有效抑制锂金属电极枝晶的生长，并有利于提高锂金属负极中锂离子沉积/溶出过程的可逆性。由此，本申请的锂金属电池能同时兼顾较高的首次库伦效率、循环性能及安全性能。
锂金属电池中，负极集流体可采用具有良好导电性及机械强度的材质，如铜箔。
可以按照本领域常规方法制备负极片。例如将锂基金属片贴合于铜箔的表面，得到负极片。所述贴合可以但不限于采用辊压实现。
锂金属电池中，正极片包括正极集流体以及层合设置在正极集流体至少一个表面上且包括正极活性材料的正极膜层。
正极集流体可以采用具有良好导电性及机械强度的材质，如铝箔。
正极膜层中，对正极活性材料的具体种类不做具体限制，可以使用可被用作锂金属电池正极活性材料的公知的材料，本领域技术人员可以根据实际需求进行选择。正极活性材料可以但不限于选自锂过渡金属氧化物及其改性材料，所述改性材料包括包覆改性材料、掺杂改性材料及包覆和掺杂改性材料中的一种或几种。锂过渡金属氧化物中，过渡金属可以是Mn、Fe、Ni、Co、Cr、Ti、Zn、V、Al、Zr、Ce及Mg中的一种或几种。作为示例，正极活性材料可以但不限于选自锂钴氧化物、锂镍氧化物、锂锰氧化物、锂镍锰氧化物、锂镍钴锰氧化物、锂镍钴铝氧化物、橄榄石结构的含锂磷酸盐及其改性材料中的一种或几种。
正极膜层中还可以包括粘结剂和/或导电剂，对粘结剂、导电剂的种类不做具体限制，本领域技术人员可以根据实际需求进行选择。作为示例，用于正极膜层的粘结剂可以但不限于选自聚偏氟乙烯(PVDF)、聚四氟乙烯(PTFE)、聚丙烯酸(PAA)、聚乙烯醇(PVA)、羧甲基纤维素钠(CMC)、海藻酸钠(SA)、聚甲基丙烯酸(PMAA)及羧甲基壳聚糖(CMCS)中的一种或几种。用于正极膜层的导电剂可以但不限于选自石墨、超导碳、乙炔黑、炭黑、科琴黑、碳点、碳纳米管、石墨烯及碳纳米纤维中的一种或几种。
可以按照本领域常规方法制备正极片。例如将正极活性材料及可选的导电剂和粘结剂分散于溶剂(例如N-甲基吡咯烷酮，简称为NMP)中，形成均匀的正极浆料，将正极浆料涂覆在正极集流体上，经烘干、冷压等工序后，得到正极片。
可以采用叠片工艺或卷绕工艺将正极片、隔离膜和负极片制成电极组件，其中隔离膜处于正极片与负极片之间起到隔离的作用。
锂金属电池中，对电解液的种类没有具体的限制，可根据需求进行选择。电解液包 括电解质盐和溶剂。
电解质盐可以但不限于选自LiPF 6(六氟磷酸锂)、LiBF 4(四氟硼酸锂)、LiClO 4(高氯酸锂)、LiAsF 6(六氟砷酸锂)、LiFSI(双氟磺酰亚胺锂)、LiTFSI(双三氟甲磺酰亚胺锂)、LiTFS(三氟甲磺酸锂)、LiDFOB(二氟草酸硼酸锂)、LiBOB(二草酸硼酸锂)、LiPO 2F 2(二氟磷酸锂)、LiDFOP(二氟二草酸磷酸锂)及LiTFOP(四氟草酸磷酸锂)中的一种或几种。
用于电解液的溶剂可以但不限于选自碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸甲乙酯(EMC)、碳酸二乙酯(DEC)、碳酸二甲酯(DMC)、碳酸二丙酯(DPC)、碳酸甲丙酯(MPC)、碳酸乙丙酯(EPC)、碳酸亚丁酯(BC)、氟代碳酸亚乙酯(FEC)、甲酸甲酯(MF)、乙酸甲酯(MA)、乙酸乙酯(EA)、乙酸丙酯(PA)、丙酸甲酯(MP)、丙酸乙酯(EP)、丙酸丙酯(PP)、丁酸甲酯(MB)、丁酸乙酯(EB)、1,4-丁内酯(GBL)、环丁砜(SF)、二甲砜(MSM)、甲乙砜(EMS)及二乙砜(ESE)中的一种或几种。
电解液中还可选地包括添加剂，其中对添加剂的种类没有具体的限制，可根据需求进行选择。作为示例，添加剂可以但不限于选自碳酸亚乙烯酯(VC)、碳酸乙烯亚乙酯(VEC)、氟代碳酸亚乙酯(FEC)、丁二腈(SN)、己二腈(ADN)、1,3-丙烯磺酸内酯(PST)、三(三甲基硅烷)磷酸酯(TMSP)及三(三甲基硅烷)硼酸酯(TMSB)中的一种或几种。
锂金属电池还包括外包装，用于封装电极组件和电解液(未示出)。
在一些实施例中，锂金属电池的外包装可以是硬壳，例如硬塑料壳、铝壳、钢壳等。锂金属电池的外包装也可以是软包，例如袋式软包。软包可以是铝塑膜包装或塑料膜包装，其中可包括聚丙烯PP、聚对苯二甲酸丁二醇酯PBT、聚丁二酸丁二醇酯PBS等中的一种或几种。
可以采用本领域公知的方法制备锂金属电池。作为示例，将正极片、隔离膜、负极片按顺序堆叠好，使隔离膜处于正极片与负极片之间起到隔离的作用，得到电极组件，也可以是经卷绕后得到电极组件；将电极组件置于包装外壳中，注入电解液并封口，得到锂金属电池。
本申请对锂金属电池的形状没有特别的限制，其可以是圆柱形、方形或其他任意的形状。如图3是作为示例的方形结构的锂金属电池5。
可选地，参照图4，外包装可包括壳体51和盖板53。壳体51可包括底板和连接于底板上的侧板，底板和侧板围合形成容纳腔。壳体51具有与容纳腔连通的开口，盖板53能 够盖设于所述开口，以封闭所述容纳腔。电极组件52封装于所述容纳腔。
锂金属电池5所含电极组件52的数量可以为一个或几个，可根据需求来调节。
在一些实施例中，锂金属电池可以组装成电池模块，电池模块所含锂金属电池的数量可以为多个，具体数量可根据电池模块的应用和容量来调节。
图5是作为一个示例的电池模块20。参照图5，在电池模块20中，多个锂金属电池5可以是沿电池模块20的长度方向依次排列设置。当然，也可以按照其他任意的方式进行排布。进一步可通过紧固件将该多个锂金属电池5进行固定。
可选地，电池模块20还可以包括具有容纳空间的外壳，多个锂金属电池5容纳于该容纳空间。
在一些实施例中，上述电池模块还可以组装成电池包，电池包所含电池模块的数量可以根据电池包的应用和容量进行调节。
图6和图7是作为一个示例的电池包30。参照图6和图7，在电池包30中可以包括电池箱和设置于电池箱中的多个电池模块20。电池箱包括上箱体31和下箱体32，上箱体31能够盖设于下箱体32，并形成用于容纳电池模块20的封闭空间。多个电池模块20可以按照任意的方式排布于电池箱中。
装置
本申请还提供了一种包含本申请的锂金属电池的装置。锂金属电池可用作所述装置的电源，也可作为所述装置的能量存储单元。装置例如为新能源汽车、电子装置、电动工具和电力储能设施等等。进一步地，所述装置可以但不限于是移动设备(例如手机、笔记本电脑等)、电动车辆(例如纯电动车、混合动力电动车、插电式混合动力电动车、电动自行车、电动踏板车、电动高尔夫球车、电动卡车等)、电气列车、船舶及卫星、储能系统等。
所述装置可根据其使用需求来选择锂金属电池、电池模块或电池包。
图8是作为一个示例的装置。该用电设备为纯电动车、混合动力电动车、或插电式混合动力电动车等。为了满足该装置对电池的高功率和高能量密度的需求，可以采用电池包或电池模块。
实施例
下述实施例更具体地描述了本申请公开的内容，这些实施例仅仅用于阐述性说明，因为在本申请公开内容的范围内进行各种修改和变化对本领域技术人员来说是明显的。除非另有声明，以下实施例中所报道的所有份、百分比、和比值都是基于重量计，而且实施例中使用的所有试剂都可商购获得或是按照常规方法进行合成获得，并且可直接使 用而无需进一步处理，以及实施例中使用的仪器均可商购获得。
实施例1
功能化隔离膜的制备
将300g硅氧化合物SiO(D v50为1μm)超声分散于200g质量浓度为1.5％的聚丙烯酸水溶液中，充分混合搅拌5小时后，用喷雾干燥机干燥，干燥温度为130℃，获得复合粒子，其包括SiO粒子及包覆于SiO粒子表面的聚丙烯酸包覆层，包覆层的厚度为10nm。
将单体(对乙烯苯磺酰)(氟磺酰)亚胺锂与碘化(丁烯)(三甲基)铵按摩尔比1:1混合于丙酮中，加入4wt％的对苯二烯和2wt％的2-乙氧基-1,2-二苯基乙酮，超声溶解后，使用UV光引发交联聚合，得到聚合物离子液体IV。聚合物离子液体IV的数均分子量约为100000，聚合物离子液体IV包含式IV所示的结构单元，其中l、m分别约为240。
Figure PCTCN2020101668-appb-000005
将质量比为95:5的复合粒子和聚合物离子液体加入溶剂NMP中，并混合均匀，得到涂覆浆料。涂覆浆料的固含量为40wt％。
利用微凹涂布法将浆料均匀涂布到10μm厚的多孔聚乙烯基材的一侧表面上，得到湿膜，将湿膜置于烘箱70℃干燥后，得到功能化隔离膜。其中，功能膜层的厚度为5μm。
正极片的制备
将正极活性材料LiNi 0.8Co 0.1Mn 0.1O 2、导电剂乙炔黑、粘结剂PVDF按质量比96:2:2进行混合，加入溶剂NMP搅拌至体系呈均一状，获得正极浆料；将正极浆料均匀涂覆在12μm厚的正极集流体铝箔上，然后在120℃下烘烤1h后，再依次经过压实、分切，获得正极片。
负极片的制备
将25μm厚的金属锂箔通过辊压贴合于8μm厚的铜箔表面，切片，得到负极片。
电解液的制备
在干燥房中，将碳酸亚乙酯(EC)、碳酸亚丙酯(PC)、碳酸二乙酯(DEC)按重量比EC:PC:DEC＝1:1:1混合，得到混合溶剂，然后将LiPF 6均匀溶解在混合溶剂中，得 到非水电解液。其中LiPF 6的浓度为1mol/L。
锂金属电池的制备
将正极片、隔离膜、负极片依次叠片制备电极组件，使隔离膜的功能膜层与负极片的锂基金属层贴合，再装入铝箔包装袋，然后依次注入电解液、封装，获得容量为1Ah的锂金属电池。
实施例2
锂金属电池的制备同实施例1，区别在于：复合粒子中，无机粒子的粒径为10nm。
实施例3
锂金属电池的制备同实施例1，区别在于：复合粒子中，无机粒子的粒径为200nm。
实施例4
锂金属电池的制备同实施例1，区别在于：复合粒子中，无机粒子的粒径为2μm。
实施例5
锂金属电池的制备同实施例1，区别在于：复合粒子中，无机粒子的粒径为20μm。
实施例6
锂金属电池的制备过程同实施例1，区别在于：复合粒子中，聚丙烯酸包覆层的厚度为1nm。
实施例7
锂金属电池的制备过程同实施例1，区别在于：复合粒子中，聚丙烯酸包覆层的厚度为20nm。
实施例8
锂金属电池的制备过程同实施例1，区别在于：复合粒子中，聚丙烯酸包覆层的厚度为100nm。
实施例9
锂金属电池的制备过程同实施例1，区别在于：复合粒子中，聚丙烯酸包覆层的厚度为1μm。
实施例10
锂金属电池的制备过程同实施例1，区别在于：功能膜层的厚度为1μm。
实施例11
锂金属电池的制备过程同实施例1，区别在于：功能膜层的厚度为10μm。
实施例12
锂金属电池的制备过程同实施例1，区别在于：功能膜层的厚度为20μm。
实施例13
锂金属电池的制备过程同实施例1，区别在于：无机粒子为单质硅。
实施例14
锂金属电池的制备过程同实施例1，区别在于：无机粒子为铝。
实施例15
锂金属电池的制备过程同实施例1，区别在于：无机粒子为锡。
实施例16
锂金属电池的制备过程同实施例1，区别在于：采用聚合物离子液体V，其包含式V所示的结构单元。
Figure PCTCN2020101668-appb-000006
聚合物离子液体V的制备：将单体(对乙烯苯磺酰)(氟磺酰)亚胺锂、碘化(对乙烯苯甲基)(甲氧基乙基)铵、丙烯腈按摩尔比1:1:1.2混合于丙酮中，加入4wt％的对苯二烯和2wt％的2-乙氧基-1,2-二苯基乙酮，超声溶解后，使用UV光引发交联聚合，得到聚合物离子液体V。聚合物离子液体V的数均分子量约为70000，l和n约为110，m约为130。
实施例17
锂金属电池的制备过程同实施例1，区别在于：采用聚合物离子液体VI，其包含式VI所示的结构单元。
Figure PCTCN2020101668-appb-000007
聚合物离子液体VI的制备：将单体对乙烯苯磺酸锂、碘化(丁烯)(三甲基)鏻、环氧乙烷按摩尔比1:1:1.2混合于丙酮中，加入4wt％的对苯二烯和2wt％的2-乙氧基-1,2-二苯基 乙酮，超声溶解后，使用UV光引发交联聚合，得到聚合物离子液体VI。聚合物离子液体VI的数均分子量约为60000，l和n约为130，m约为150。
实施例18
锂金属电池的制备过程同实施例1，区别在于：包覆层为聚乙烯苯磺酸包覆层。
实施例19
锂金属电池的制备过程同实施例1，区别在于：无机粒子未经过包覆处理。
实施例20
锂金属电池的制备过程同实施例1，区别在于：未添加聚合物离子液体，无机粒子未经包覆处理，无机粒子通过粘结剂PVDF粘结在基材表面，PVDF的分子量为100000。
实施例21
锂金属电池的制备过程同实施例1，区别在于：未添加聚合物离子液体。
对比例1
锂金属电池的制备过程同实施例1，区别在于：隔离膜未经过处理。
对比例2
锂金属电池的制备过程同实施例1，区别在于：隔离膜表面只涂覆聚合物离子液体IV，涂层厚度为5μm。
对比例3
锂金属电池的制备过程同实施例1，区别在于：无机粒子为SiO 2，且无机粒子未经过包覆处理。
测试部分
(1)首次库伦效率及循环性能测试
在25℃下，将锂金属电池以1.5mA/cm 2的恒定电流充电至4.25V，之后以4.25V恒压充电至电流降到0.3mA/cm 2，得首周充电比容量(C c1)；再以1.5mA/cm 2的恒定电流放电至3.0V，得首周放电比容量(C d1)。如此反复充放电至第n周，得到锂金属电池循环n周后的放电比容量记为C dn。
首次库伦效率＝首周放电比容量(C d1)/首周充电比容量(C c1)
容量保持率＝循环n周后的放电比容量(C dn)/首周放电比容量(C d1)
(2)负极极片表面锂枝晶检测
将按(1)中方法循环第100周后满充状态的锂金属电池拆解，通过光学显微镜观察金属锂负极片的表面形貌、通过电子显微镜观察金属锂负极片的截面形貌，观察锂沉积层厚度，并与理论沉积厚度相比。其中，无：厚度增长比例低于150％，可认为无锂枝晶 生成；轻微：厚度增长比例在150％～200％内；中等：厚度增长比例在＞200％～250％内；严重：厚度增长比例大于250％。
(3)无机粒子粒径测试
采用激光衍射方法测试粒径分布D v50(马尔文激光粒度仪300)。
表1：实施例1～21和对比例1～3的锂金属电池的参数及性能测试结果
Figure PCTCN2020101668-appb-000008
表1中，PAA表示聚丙烯酸；PSS表示聚乙烯苯磺酸。
由实施例1～21与对比例1～3的对比可知，采用本申请的功能化隔离膜，锂金属电池 的首次库伦效率及循环容量保持率均得到改善。
拆开电池使用光学显微镜观察金属锂负极片表面，采用本申请隔离膜的锂金属电池中，金属锂负极片的表面形成的界面膜较薄且致密，而对比例1的金属锂负极片表面覆盖较厚的、蓬松的褐色沉积物，且沉积物中含有大量的锂枝晶，金属锂负极片表面大量锂枝晶是导致电池短路的主要原因，且锂枝晶表面积大、活性高，易与电解液剧烈反应，导致金属锂表面SEI膜持续重组，消耗电解液和活性锂，导致首次库伦效率和循环效率降低，降低电池容量、缩短电池循环寿命。该结果说明，采用本申请的功能化隔离膜能有效提升电池的循环性能、抑制锂枝晶。
实施例1、13～15与对比例3的结果可知，无机粒子为能与锂发生合金化的SiO、Si、Al、Sn等时，能改变金属锂负极表面的锂组成，锂合金的形成能调控锂沉积/溶出的行为，抑制锂金属电极枝晶生长，有利于提高锂沉积/溶出过程的可逆性，电池表现出良好的循环性能。而使用无活性的无机粒子如SiO 2时，电池锂金属负极枝晶严重，电池容量衰减快。
实施例1～5的结果可知，无机粒子的粒径大小对电池的性能影响较大。粒径较小时，涂层内孔隙多，使得电解液的物理消耗量过大，导致电池衰减加速。而粒径过大时，会导致涂层一致差，导致涂层对锂金属表面的影响不一致。
由实施例1、6～10、18和实施例19的结果可知，聚合物包覆层及其厚度影响电池的性能。具体表现为，无包覆层(实施例19)或包覆层较薄(实施例6)，电池的容量衰减较快，循环寿命相应地较低。这是因为聚丙烯酸包覆层能在锂合金化之后，与锂合金原位发生微反应，加强与锂合金之间的作用力，有利于抑制锂合金在电池充放电过程中的体积变化，且原位化学反应形成的有机酸锂结构，可形成锂离子传输通道，促进锂离子的传递。聚合物包覆层的厚度适当，能改善电池的首次库伦效率及循环性能。
由实施例1和10～12的结果可知，功能膜层的厚度过薄不利于形成稳定合金化层，而功能膜层的厚度过厚则影响锂离子的传递，导致电池循环中极化逐渐增大，容量衰减加快。厚度适中的功能膜层可有效抑制电解液与锂金属的接触，降低副反应，改善电池的循环性能。
由实施例1、16～18和实施例20的结果可知，功能膜层中聚合物的类型也有明显影响。使用带正、负电荷基团结构的聚合物离子液体，其中正电荷基团结构能够与包覆层中酸根负离子结构相互作用，形成化学键缠绕结构，提高功能膜层的强度；聚合物离子液体中的负电荷基团结构，能加强锂离子正电荷的快速传递，降低阻抗和过电位。因此，在功能膜层中添加聚合物离子液体，能更有效地改善锂金属电池的锂枝晶问题，同 时对电池的首次库伦效率及循环性能的改善也更为显著。
综上，采用本申请的功能化隔离膜，可以在锂金属负极表面构建了一层类似SEI膜的保护层，能够抑制锂金属电极的枝晶问题，减少锂金属与电解液之间的界面副反应，提高锂金属电池的性能。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到各种等效的修改或替换，这些修改或替换都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以权利要求的保护范围为准。

Claims (17)

  1. 一种功能化隔离膜，包括多孔基材以及设置于所述多孔基材至少一个表面的功能膜层；
    其中，所述功能膜层包含无机粒子，所述无机粒子能与金属锂发生可逆反应形成锂合金。
  2. 根据权利要求1所述的功能化隔离膜，其中，所述无机粒子的体积平均粒径D v50为10nm～20μm，可选的为50nm～10μm，进一步可选的为200nm～2μm。
  3. 根据权利要求1或2所述的功能化隔离膜，其中，所述无机粒子选自硅、硅氧化合物SiO a、镁、铝、锌、铟、锑、银、金、锗及锡中的一种或几种，其中0＜a＜2。
  4. 根据权利要求1至3任一项所述的功能化隔离膜，其中，所述无机粒子的至少部分表面包覆有聚合物包覆层，所述包覆层含有与锂离子进行可逆键合的基团；
    可选的，所述与锂离子进行可逆键合的基团包括酸根基团、氨基、亚氨基、巯基及多硫基团(-S b-，b≥2)中的一种或几种，进一步可选的，所述酸根基团包括羧酸基团、磺酸基团、亚磺酸基团及磷酸基团中的一种或几种。
  5. 根据权利要求4所述的功能化隔离膜，其中，所述包覆层包括含有所述酸根基团的聚烯酸；可选的，所述聚烯酸包括聚丙烯酸及聚乙烯苯磺酸中的一种或几种。
  6. 根据权利要求1至5任一项所述的功能化隔离膜，其中，所述包覆层的厚度为1nm～1μm，可选的为5nm～200nm，进一步可选的为20nm～100nm。
  7. 根据权利要求1至6任一项所述的功能化隔离膜，其中，所述功能膜层还包括聚合物离子液体。
  8. 根据权利要求7所述的功能化隔离膜，其中，所述聚合物离子液体包含式I和式II所示的结构单元；
    Figure PCTCN2020101668-appb-100001
    其中，
    X为带负电荷的阴离子，可选的为-COO －、-SO 3 －、-SO 2N －SO 2R h、-RCOO －、-RSO 3 －或-RSO 2N －SO 2R f；
    R和R 2各自独立地为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基；
    R 1和R 4各自独立地为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基；
    R 3、R h和R f各自独立地为F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基；
    Y为N或P，p为3；或者，Y为S，p为2；
    l和m为相同或不同的正整数；可选的，1≤l≤2500、1≤m≤2500；可选的，l:m＝1:(0.5～1.5)。
  9. 根据权利要求8所述的功能化隔离膜，其中，
    R 2为C1～C4的亚烷基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C4的亚烷基；和/或，
    R 3为-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) sCH 3，s为1～8；和/或，
    R 1和R 4各自独立地为H、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) vCH 3，v为1～8。
  10. 根据权利要求8至9任一项所述的功能化隔离膜，其中，所述聚合物离子液体还包含式III所示结构单元；
    Figure PCTCN2020101668-appb-100002
    其中，
    R 5为C1～C10的亚烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的亚烃基，可选的为-(CH 2) t-或-(CH 2) q-O-(CH 2) r-，t为1～8，q为0～4，r为0～4，q和r不同时为0；
    R 6为H、F、Cl、Br、I、-CN、C1～C10的烃基、或含F、Cl、Br、I、N、O、S、Si、B及P中的一种或几种的C1～C10的烃基，可选的为H、-CN、-CH 3、-C 2H 5、直链-C 3H 7、直链-C 4H 9或-(CH 2CH 2O) uCH 3，u为1～8；
    n为正整数；可选的，1≤n≤2500；可选的，l:m:n＝1:(0.5～1.5):(0～1.5)。
  11. 根据权利要求8至10任一项所述的功能化隔离膜，其中，所述聚合物离子液体的数均分子量为40000～1000000。
  12. 根据权利要求8至11任一项所述的功能化隔离膜，其中，所述功能膜层中，所述无机粒子与所述聚合物离子液体的质量比为(80～99):(1～20)，可选的为(90～98):(2～10)。
  13. 根据权利要求1所述的功能化隔离膜，其中，所述功能膜层的厚度为0.1μm～20μm，可选的为1μm～10μm。
  14. 根据权利要求1所述的功能化隔离膜，其中，所述基材为聚合物基材；
    可选的，所述基材的厚度为5μm～25μm。
  15. 一种功能化隔离膜的制备方法，包括在多孔基材的至少一个表面形成包含无机粒子的功能膜层的步骤，其中所述无机粒子能与金属锂发生可逆反应形成锂合金。
  16. 一种锂金属电池，包括：正极片；
    负极片，包括锂基金属层；
    隔离膜，所述隔离膜为根据权利要求1至14任一项所述的功能化隔离膜或根据权利要求15所述方法制备的功能化隔离膜，所述功能膜层与所述锂基金属层接触设置；以及
    电解液。
  17. 一种装置，包括根据权利要求16所述的锂金属电池。
PCT/CN2020/101668 2019-07-26 2020-07-13 功能化隔离膜、其制备方法、锂金属电池和包含锂金属电池的装置 WO2021017801A1 (zh)

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