Passivated lithium powder and preparation method thereof, negative plate, battery and electric equipment

Abstract

The invention provides passivated lithium powder and a preparation method thereof, a negative plate, a battery and electric equipment, and the passivated lithium powder comprises lithium powder and a passivation layer coating the surface of the lithium powder; the passivation layer comprises a product generated by in-situ reaction of a compound as shown in a formula 1 and the lithium powder; cnHx (OH) yFz formula 1, in the formula 1, n is greater than or equal to 2 and less than or equal to 50, y is greater than or equal to 1, z is greater than or equal to 1, and x is greater than or equal to 1; the products include LiF and CnHx (OLi) y. The passivated lithium powder has excellent air stability and deliquescence resistance, and can stabilize an SEI film on the surface of a pole piece after being applied to the pole piece.

Description

Technical Field

[0001] The invention relates to a passivated lithium powder, in particular to a passivated lithium powder and a preparation method thereof, a negative electrode sheet, a battery and an electrical device, belonging to the field of secondary batteries. Background Art

[0002] During the first charge and discharge process of lithium-ion batteries, the organic electrolyte will be reduced and decomposed on the surface of the negative electrode to form a solid electrolyte layer, which irreversibly consumes the Li from the positive electrode. +c , resulting in low first-cycle Coulomb efficiency of the battery.

[0003] Negative electrode lithium supplement agent passivated lithium powder is a multifunctional, high-energy-density lithium supplement material that can be adapted to a variety of negative electrodes such as graphite negative electrodes and silicon-based negative electrodes. Passivated lithium powder uses metallic lithium as raw material. Metallic lithium has high chemical reactivity. After being processed into powder, it has a larger specific surface area and higher reactivity. In actual application, a series of passivation measures will be taken to build a passivation layer on the surface of lithium powder particles to reduce the reactivity of metallic lithium in the air.

[0004] However, the current production methods and passivation methods of passivated lithium powder focus more on whether the preparation process of the product itself is simple and easy. Further exploration is still needed to explore passivated lithium powder with better air stability, deliquescent resistance and positive effects on the SEI film on the electrode surface. Summary of the invention

[0005] The present invention provides a passivated lithium powder, which has excellent air stability and deliquescent resistance, and can stabilize the SEI film on the surface of the pole piece after being applied to the pole piece.

[0006] The present invention also provides a method for preparing passivated lithium powder. The preparation method has a simple process and can prepare the passivated lithium powder.

[0007] The present invention also provides a negative electrode sheet, which comprises the above-mentioned passivated lithium powder.

[0008] The present invention also provides a battery, which comprises the negative electrode sheet.

[0009] The present invention also provides an electrical device, which comprises the battery.

[0010] In one aspect, the present invention provides a passivated lithium powder, the passivated lithium powder comprising lithium powder and a passivation layer coated on the surface of the lithium powder;

[0011] The passivation layer includes a product generated by an in-situ reaction of the compound represented by Formula 1 and the lithium powder;

[0012] C n H x (OH) y Fz Formula 1

[0013] In formula 1, 2≤n≤50, y≥1, z≥1, x≥1;

[0014] The products include LiF and C n H x (OLi) y .

[0015] As for the passivated lithium powder as described above, the passivation layer also includes Li2CO3.

[0016] For the passivated lithium powder as described above, 7≤n≤50.

[0017] For the passivated lithium powder as described above, the compound represented by Formula 1 has a melting point of ≤100°C and a boiling point of ≥220°C.

[0018] For the passivated lithium powder as described above, the compound shown in Formula 1 includes one or more of 4-fluoro-2-isopropoxyphenol and 4,5-difluoro-2-methylphenol.

[0019] The passivated lithium powder as described above, wherein the D50 particle size of the passivated lithium powder is 30 um to 60 um;

[0020] And / or, the thickness of the passivation layer is 150 nm to 400 nm.

[0021] Another aspect of the present invention provides a method for preparing the passivated lithium powder as described above, comprising the following steps:

[0022] In an argon atmosphere, the compound represented by formula 1 is mixed with an inert solvent to obtain a mixed system; lithium powder is added to the mixed system and reacted at 180° C. to 210° C. to obtain the passivated lithium powder.

[0023] The preparation method as described above, wherein the inert solvent comprises liquid paraffin;

[0024] And / or, the volume ratio of the inert solvent to the compound represented by Formula 1 is 70:30 to 99:1, preferably 95:5 to 98:2;

[0025] And / or, the reaction is carried out under stirring conditions, and the stirring rate is 5000-20000 rpm, preferably 8000-11000 rpm;

[0026] And / or, the reaction time is 0.5 to 24 hours, preferably 0.5 to 1.5 hours.

[0027] The preparation method as described above, after the reaction is completed, further comprises: cooling the temperature of the reaction system to below the melting point of metallic lithium, and then performing a vacuum drying treatment on the reaction system;

[0028] The temperature of the vacuum drying treatment is ≤180°C, preferably 130-140°C.

[0029] The preparation method as described above, after the vacuum drying treatment is completed, further comprises: introducing CO2 gas into the reaction system at a temperature of 120-179°C, preferably 130-140°C.

[0030] In another aspect, the present invention provides a negative electrode sheet, comprising the passivated lithium powder as described above or the passivated lithium powder prepared by the preparation method as described above.

[0031] Another aspect of the present invention provides a battery, comprising the negative electrode sheet as described above.

[0032] Another aspect of the present invention provides an electrical device including the battery as described above.

[0033] The passivation lithium powder provided by the present invention comprises lithium powder and a passivation layer coated on the surface of the lithium powder. The passivation layer of the present invention comes from a compound of a specific composition, including LiF and lithium alcohol. Not only can LiF exert its good ability to resist corrosion of H2O, O2 and other substances in the air to the passivation lithium powder, and is not easy to absorb water and deliquesce, but lithium alcohol, as a strong nucleophilic reagent, is conducive to the generation of Li2CO3 in the passivation layer after CO2 is introduced in the subsequent process step. At the same time, the presence of the nucleophilic reagent lithium alcohol contributes to the formation of a dense SEI layer of the lithium-replenishing pole piece. Under the synergistic effect of LiF and lithium alcohol, the passivation lithium powder has excellent air stability and deliquesce resistance, and after the passivation lithium powder is applied to the pole piece, the SEI film on the surface of the pole piece can be stabilized. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0035] Figure 1 It is a schematic diagram of the structure of passivated lithium powder provided in a specific embodiment of the present invention.

[0036] Description of reference numerals:

[0037] a-passivation layer, b-lithium powder.

[0038] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Figure 1 The schematic diagram of the structure of the passivated lithium powder provided in one specific embodiment of the present invention is as follows: Figure 1 As shown, the present invention provides a passivated lithium powder on one hand, the passivated lithium powder comprises lithium powder b and a passivation layer a coated on the surface of the lithium powder; the passivation layer a comprises a product generated by an in-situ reaction of a compound represented by Formula 1 and lithium powder; C n H x (OH) y F z Formula 1; in Formula 1, 2≤n≤50, x+y+z=2n, y≥1, z≥1; the products include LiF and C n H x (OLi) y .

[0041] In detail, the passivated lithium powder provided by the present invention is a core-shell structure, wherein the lithium powder is an inner core structure, and the passivation layer coated on the surface of the lithium powder is an outer layer structure.

[0042] The compound shown in Formula 1 is used as a passivating agent to react with lithium powder on the surface of lithium powder to obtain a passivation layer, wherein the passivation layer includes LiF and C n H x (OLi) y In the in-situ reaction process, the products between the compound shown in Formula 1 and lithium powder include LiF, C n H x (OLi) y In addition, it also includes lithium-carbon alloys generated by the reaction of metallic lithium with a partially coked fluorinating agent.

[0043] The specific components in the passivation layer can be detected by common detection methods in the art. For example, after the passivation lithium powder is sampled in a glove box, it is vacuum transferred to an XPS test chamber for XPS testing.

[0044] Wherein, in the compound represented by Formula 1, n includes but is not limited to 2, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50 or a range between any two thereof.

[0045] In a specific embodiment, the compound represented by Formula 1 of the present invention is a fluorinated phenol, wherein the fluorinated phenol, as a fluorinating agent for metallic lithium, has the advantages of low cost, easy availability, high temperature stability, and controllable degree of fluorination.

[0046] The passivated lithium powder provided by the present invention has excellent air stability and deliquescence resistance, and after the passivated lithium powder is applied to the pole piece, the SEI film on the surface of the pole piece can be stabilized. The inventor analyzes this and believes that the reason may be that: the lithium powder is passivated by the compound shown in Formula 1, and the activity of the CF bond and the reactivity with Li can be improved by controlling the position of -F, thereby controlling the distribution and content of LiF in the passivation layer. LiF has good resistance to the corrosion of H2O, O2 and other substances in the air to the passivated lithium powder, and is not easy to absorb water and deliquescence, which can ensure the fluidity and stability of the material when the passivated lithium powder is used in the dew point room; LiF is an important component in SEI, with stable mechanical properties and a wide electrochemical window, and has the effect of stabilizing SEI. At the same time, phenolic hydroxyl hydrogen has a certain activity and can react with metallic lithium, and Li atoms replace H to generate alcohol lithium -OLi; alcohol lithium, as a nucleophilic reagent, is more likely to react with the nucleophilic reagent CO2 to generate Li2CO3; the unsaturated bond in the benzene ring can provide enough electron cloud to ensure the reactivity of C-OH bond and CF bond. Compared with direct coating of LiF / Li2CO3 on the surface of metallic lithium powder by physical methods, the passivation layer constructed by the reaction of passivating agent combined with CO2 and metallic lithium has closer contact with metallic lithium and more uniform coating.

[0047] Furthermore, in a specific embodiment of the present invention, the passivation layer also includes Li2CO3.

[0048] Li2CO3 in the passivation layer can be obtained by vacuum drying to remove the solvent after the in-situ reaction is completed, and then introducing a certain amount of CO2 to react under high temperature conditions.

[0049] Li2CO3 exists stably in the air and is not easy to absorb H2O in the air to form agglomerates, which can improve the stability of passivated lithium powder in the air to a certain extent.

[0050] The present invention does not limit the content of Li2CO3 and LiF, C n H x (OLi) y The mass relationship between them can be selected according to actual needs to better play the synergistic effect between the various components in the passivation layer.

[0051] In a specific embodiment, the mass percentage of Li2CO3 in the passivation layer is 25.2%, the mass percentage of LiF is 48.3%, and the mass percentage of C n H x (OLi)y The mass percentage is 20.5%.

[0052] Furthermore, in a specific embodiment of the present invention, 7≤n≤50.

[0053] In detail, n includes but is not limited to 10, 15, 20, 25, 30, 35, 40, 45, 50 or a range between any two of them.

[0054] When the number of carbon atoms in the compound represented by Formula 1 is more, the boiling point of the compound represented by Formula 1 is higher, which can ensure that the compound represented by Formula 1 will not vaporize during the coating process, thereby fully participating in the reaction.

[0055] Furthermore, in a specific embodiment of the present invention, the compound represented by Formula 1 has a melting point of ≤100°C and a boiling point of ≥210°C.

[0056] In detail, the melting point includes, but is not limited to, 100°C, 95°C, 90°C, 85°C, 80°C, 75°C, 70°C or any range not higher than 100°C.

[0057] The boiling point includes, but is not limited to, 210°C, 215°C, 220°C, 225°C, 230°C, 235°C, 240°C, 245°C or any range ≥ 210°C.

[0058] When the melting point and boiling point of the compound shown in Formula 1 are within the above range, it not only has high stability and can avoid the adverse effects on the efficiency and effect of the in-situ reaction caused by phase conversion during the in-situ reaction, but also the compound with the above melting point and boiling point can better react with the lithium powder in situ, and the formed passivation layer is more tightly combined with the lithium powder as the core, and has excellent stability.

[0059] Furthermore, in a specific embodiment of the present invention, the compound represented by Formula 1 includes one or more of 4-fluoro-2-isopropoxyphenol and 4,5-difluoro-2-methylphenol.

[0060] The above-mentioned type of compounds not only have melting points and boiling points within a suitable range, but can also be obtained through commercial channels, reducing the difficulty of preparation. At the same time, they can better achieve in-situ reaction with lithium powder, improve the stability and deliquescent resistance of passivated lithium powder, and after being applied to the electrode, are conducive to the formation of a stable SEI film.

[0061] Further, in a specific embodiment of the present invention, the D50 particle size of the passivated lithium powder is 20 um to 50 um;

[0062] And / or, the thickness of the passivation layer is 100 nm~800 nm.

[0063] In detail, the D50 particle size of the passivated lithium powder can be detected by common detection methods in the art, such as a laser particle size analyzer, a sieving method, a scanning electron microscope, and the like.

[0064] Specifically, the D50 particle size of the passivated lithium powder includes but is not limited to 20 um, 25 um, 30 um, 35 um, 40 um, 45 um, 50 um or a range between any two of them.

[0065] When the D50 particle size of the passivation lithium powder is within the above range, it can be adapted to different lithium replenishment scenarios. For example, the graphite negative electrode requires a small amount of lithium replenishment, and the use of a passivation lithium powder product with a smaller D50 during lithium replenishment can improve the uniformity of lithium replenishment; the silicon-carbon negative electrode requires a large amount of lithium replenishment, and the use of a passivation lithium powder product with a larger D50 during lithium replenishment can improve the lithium replenishment efficiency.

[0066] The thickness of the passivation layer in the present invention refers to the average thickness of the passivation layer, which can also be detected by common detection methods in the art, such as scanning electron microscopy, transmission electron microscopy, atomic force microscopy, etc.

[0067] Specifically, the thickness of the passivation layer includes but is not limited to 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm or a range between any two of them.

[0068] When the passivation layer thickness of the passivation lithium powder is within the above range, it can be adapted to different lithium replenishment scenarios. For example, when the dew point environment is high, a passivation lithium powder with a thicker passivation layer is used, and when the lithium replenishment demand is high, a passivation lithium powder with a thinner passivation layer is used.

[0069] Another aspect of the present invention provides a method for preparing the passivated lithium powder as described above, comprising the following steps:

[0070] In an argon atmosphere, the compound represented by formula 1 is mixed with an inert solvent to obtain a mixed system; lithium powder is added to the mixed system and reacted at 180° C. to 210° C. to obtain passivated lithium powder.

[0071] The inert solvent in the present invention refers to a solvent that reacts with metallic lithium or lithium alloy and does not react with the compound represented by Formula 1.

[0072] In detail, the compound represented by Formula 1 is mixed with an inert solvent. After stirring, the compound represented by Formula 1 is uniformly dispersed in the mixed system, which can promote the subsequent reaction, and the inert solvent provides a stable medium for the subsequent reaction. Subsequently, lithium powder is added to the inert system, and the lithium powder reacts with the compound represented by Formula 1 in situ at 180° C.-210° C. to form a passivation layer on the surface of the lithium powder to obtain passivated lithium powder.

[0073] Specifically, the reaction temperature includes but is not limited to 180° C., 190° C., 200° C., 210° C., 220° C. or a range between any two thereof.

[0074] The preparation method provided by the present invention can prepare passivated lithium powder with excellent stability and deliquescence resistance. At the same time, the passivated lithium powder can form a stable SEI film after being used in a pole piece.

[0075] Further, in one embodiment of the present invention, the inert solvent includes liquid paraffin;

[0076] and / or, the volume ratio of the inert solvent to the compound represented by Formula 1 is 70:30 to 99:1, preferably 95:5 to 98:2;

[0077] And / or, the reaction is carried out under stirring conditions, and the stirring rate is 5000-20000 rpm, preferably 8000-11000 rpm;

[0078] And / or, the reaction time is 0.5 to 24 h, preferably 0.5 to 1.5 h.

[0079] In detail, based on the overall volume of the mixed system consisting of the inert solvent and the compound shown in Formula 1, the volume mass fraction of the compound shown in Formula 1 includes but is not limited to 1%, 5%, 10%, 15%, 20%, 25%, 30% or a range composed of any two thereof. When the volume of the inert solvent and the compound shown in Formula 1 has the above relationship, the inert solvent can effectively dilute the reactants, control the reaction rate, and improve the uniformity of various components in the passivation layer.

[0080] Preferably, the volume mass fraction of the compound represented by Formula 1 includes, but is not limited to, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or a range between any two thereof. When the volume of the inert solvent and the compound represented by Formula 1 has the above relationship, the dispersing effect of the inert solvent can be better exerted.

[0081] The reaction is carried out under stirring, and the stirring rate includes but is not limited to 5000rpm, 6000rpm, 8000rpm, 10000rpm, 12000rpm, 14000rpm, 16000rpm, 18000rpm, 20000rpm or the range composed of any two thereof. Preferably, the stirring rate includes but is not limited to 8000, 8500, 9000, 9500, 10000, 10500, 11000 or the range composed of any two thereof. When the reaction is stirred under the above stirring rate, the reaction rate can be increased, the uniformity of the passivation layer can also be increased, and then the stability of the passivated lithium powder can be improved.

[0082] The reaction time includes but is not limited to 0.5h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h or a range consisting of any two thereof; preferably, the reaction time is 0.5h, 0.6h, 0.8h, 1.0h, 1.2h, 1.4h, 1.5h or a range consisting of any two thereof.

[0083] When the reaction time is controlled within the above range, the thickness of the passivation layer in the passivated lithium powder can be effectively controlled so that the thickness is within a suitable range, which can not only play the role of the passivation layer but also play the effect of lithium supplementation.

[0084] Furthermore, in a specific embodiment of the present invention, after the reaction is completed, it also includes: cooling the temperature of the reaction system to below the melting point of metallic lithium, and then vacuum drying the reaction system; the temperature of the vacuum drying treatment is ≤180°C, preferably 130~140°C.

[0085] After the reaction is completed, inert solvents or other impurities may remain on the surface of the obtained passivated lithium powder. In order to improve the purity and stability of the final passivated lithium powder product, the temperature of the reaction system is cooled to below the melting point of metallic lithium and then the reaction system is vacuum dried at no higher than 180°C.

[0086] Among them, the temperature of vacuum drying treatment is preferably 130-140°C. For example, the temperature of vacuum drying treatment includes but is not limited to 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C or a range between any two of them.

[0087] When the temperature of the vacuum drying process is within the above range, it can not only effectively avoid the structure of the passivated lithium powder being damaged by excessive temperature, but also improve the efficiency of the vacuum drying process.

[0088] Furthermore, in a specific embodiment of the present invention, after the vacuum drying treatment is completed, it also includes: introducing CO2 gas into the reaction system at a temperature of 120-179°C, preferably 130-140°C.

[0089] After the vacuum drying treatment is completed, carbon dioxide is introduced into the reaction system, and the carbon dioxide reacts with the lithium alcohol in the passivation layer to form lithium carbonate, which can further improve the stability of the passivation lithium powder.

[0090] In detail, the temperature after the introduction of CO2 includes but is not limited to 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 179°C or a range between any two of them.

[0091] In another aspect, the present invention provides a negative electrode sheet, comprising the passivated lithium powder as described above or the passivated lithium powder prepared by the preparation method as described above.

[0092] In detail, since the negative electrode sheet includes the passivation lithium powder as described above or the passivation lithium powder prepared by the preparation method as described above, it helps to stabilize the SEI structure of the negative electrode sheet and play a role in lithium supplementation.

[0093] It can be understood that the negative electrode sheet of the present invention specifically includes a negative electrode current collector and a negative electrode active layer formed of a negative electrode active material and disposed on the surface of the negative electrode current collector.

[0094] When preparing the negative electrode, the negative electrode active material, the conductive agent, and the binder can be dispersed in an appropriate amount of deionized water, and fully stirred and mixed to form a uniform negative electrode slurry; the negative electrode slurry is evenly coated on the negative electrode current collector, and after drying, rolling and slitting, a negative electrode sheet is obtained. In a specific embodiment, the negative electrode active layer includes 70-99 wt% of the negative electrode active material, 0.5-15 wt% of the conductive agent, and 0.5-15 wt% of the binder according to the mass percentage, and further includes 80-98 wt% of the negative electrode active material, 1-10 wt% of the conductive agent, and 1-10 wt% of the binder.

[0095] Among them, the material of the negative electrode current collector layer can be at least one of copper foil, nickel foam, and copper foam; the conductive agent can be selected from at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, and graphene; the binder can be selected from at least one of carboxymethyl cellulose, styrene-butadiene rubber, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers containing ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyvinyl alcohol, and sodium polyacrylate; the negative electrode active material can be at least one of graphite, hard carbon, soft carbon, mesophase carbon microbeads, silicon-based negative electrode materials (mainly including silicon oxide, silicon-carbon negative electrode), tin-based negative electrode materials (mainly including tin and tin alloy), etc.

[0096] Another aspect of the present invention provides a battery, comprising the negative electrode sheet as described above.

[0097] It is conceivable that the battery of the present invention includes, in addition to the above-mentioned negative electrode sheet, a positive electrode sheet, an electrolyte and a separator.

[0098] The present invention does not strictly limit the positive electrode active material in the positive electrode sheet, for example, it can be at least one of lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, lithium manganese oxide, nickel cobalt manganese ternary material, nickel cobalt aluminum ternary material, lithium iron phosphate (LFP), lithium nickel manganese oxide, lithium-rich manganese-based materials, etc.

[0099] The present invention does not strictly limit the selection of the electrolyte, and may include one or more of the solvents commonly used in the current battery electrolyte, and the electrolyte lithium salts commonly used in the current electrolyte, for example: the solvent may be ethylene carbonate, propylene carbonate, butylene carbonate, fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), diethyl carbonate (DEC), difluoroethylene carbonate (DFEC), dipropyl carbonate, ethyl methyl carbonate (EMC), ethyl acetate, ethyl propionate, propyl acetate, propyl propionate, cyclopentane, γ-butyrolactone, etc.; the lithium salt may be, for example, one or more of lithium hexafluorophosphate (LiPF6), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethylsulfonyl)imide (LiTFSI).

[0100] The present invention does not strictly limit the material selection of the diaphragm, which can be a diaphragm material commonly used in current batteries, such as a polypropylene diaphragm (PP), a polyethylene diaphragm (PE), a polypropylene / polyethylene double-layer composite film (PP / PE), a polyimide electrospinning diaphragm (PI), a polypropylene / polyethylene / polypropylene three-layer composite film (PP / PE / PP), a cellulose non-woven fabric diaphragm, or a diaphragm with a ceramic coating.

[0101] When preparing lithium-ion batteries, the positive electrode sheet, separator and negative electrode sheet are wound or stacked to obtain a bare cell, and the bare cell is packaged in a pre-stamped aluminum-plastic film bag. After the packaged battery is dried at 85°C, the electrolyte is injected into the dry battery, and the battery is placed, formed and sealed for the second time to complete the preparation of the lithium-ion battery.

[0102] Another aspect of the present invention provides an electrical device including the battery as described above.

[0103] The present invention does not limit the specific types of electrical equipment, and may include electric vehicles, mobile phones, smart homes, robots, drones, electronic cigarettes, speakers, and any other equipment that requires batteries to power them.

[0104] The electrical equipment provided by the present invention comprises the above-mentioned battery and thus has good electrochemical performance and stability.

[0105] The passivated lithium powder provided by the present invention is described in detail below through specific examples.

[0106] Unless otherwise specified, the reagents, materials and instruments used in the following examples are conventional reagents, conventional materials and conventional instruments in the art and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0107] Example 1

[0108] The preparation method of the passivated lithium powder provided in this embodiment comprises the following steps:

[0109] 1. Under an argon atmosphere, liquid paraffin and 4-fluoro-2-isopropoxy-phenol (liquid at room temperature, boiling point 231.1°C) were uniformly mixed in a volume ratio of 97:3 to obtain a mixed system;

[0110] 2. Add lithium powder to the mixed system at a solid-liquid ratio of 10:1, heat to 187°C at 5°C / min, start low-speed stirring after the temperature stabilizes, and after the temperature stabilizes at 187°C again, turn on high-speed stirring to 11000 rpm and maintain for 10 min, then stir at a low speed of 300 rpm and keep at 187°C for 30 min.

[0111] 3. After the system temperature is naturally cooled to 130°C, inject it into the filter to remove excess solvent, then transfer it to a vacuum dryer to remove excess solvent by vacuuming, and maintain vacuum at 130°C for 30 minutes.

[0112] 4. Use high-purity CO2 with a purity of 99.996% to break the vacuum, and keep the system in a CO2 atmosphere for 60 min at a temperature of 130°C. After cooling, the passivation layer contains LiF, Li2CO3, C9H 10 Passivated lithium powder of FO2Li (lithium alcohol) and organic matter, where the organic matter comes from part of the inert organic solvent during the molten emulsification of metallic lithium and the charred fragments of the passivator molecules.

[0113] Example 2

[0114] The preparation method of the passivated lithium powder provided in this embodiment comprises the following steps:

[0115] 1. Under an argon atmosphere, liquid paraffin and 4-fluoro-2-isopropoxy-phenol (liquid at room temperature, boiling point 231.1°C) were uniformly mixed in a volume ratio of 97:3 to obtain a mixed system;

[0116] 2. Add lithium powder to the mixed system at a solid-liquid ratio of 10:1, heat to 195°C at 5°C / min, start low-speed stirring after the temperature stabilizes, and after the temperature stabilizes at 195°C again, turn on high-speed stirring to 11000 rpm and maintain for 10 min, then stir at a low speed of 300 rpm and keep at 195°C for 30 min.

[0117] 3. After the system temperature is naturally cooled to 135°C, inject it into the filter to remove excess solvent, then transfer it to a vacuum dryer to remove excess solvent by vacuuming, and maintain vacuum at 135°C for 30 minutes.

[0118] 4. Use high-purity CO2 with a purity of 99.996% to break the vacuum, and keep the system in a CO2 atmosphere for 60 min at a temperature of 130°C. After cooling, the passivation layer contains LiF, Li2CO3, C9H 10 Passivation lithium powder of FO2Li (lithium alcohol) and organic matter.

[0119] Example 3

[0120] The preparation method of the passivated lithium powder provided in this embodiment comprises the following steps:

[0121] 1. Under an argon atmosphere, liquid paraffin and 4,5-difluoro-2-methylphenol (liquid at room temperature, boiling point 210°C) were uniformly mixed in a volume ratio of 97:3 to obtain a mixed system;

[0122] 2. Add lithium powder to the mixed system at a solid-liquid ratio of 10:1, heat to 187°C at 5°C / min, start low-speed stirring after the temperature stabilizes, and after the temperature stabilizes at 187°C again, turn on high-speed stirring to 9000 rpm and maintain for 10 min, then stir at a low speed of 500 rpm and keep at 187°C for 30 min.

[0123] 3. After the system temperature is naturally cooled to 130°C, inject it into the filter to remove excess solvent, then transfer it to a vacuum dryer to remove excess solvent by vacuuming, and maintain vacuum at 130°C for 30 minutes.

[0124] 4. Use high-purity CO2 with a purity of 99.996% to break the vacuum, and keep the system in the CO2 atmosphere for 60 minutes, with the temperature controlled at 130°C. After cooling, a passivation lithium powder containing LiF, Li2CO3, lithium alcohol and organic matter in the passivation layer is obtained.

[0125] Example 4

[0126] The preparation method of the passivated lithium powder provided in this embodiment comprises the following steps:

[0127] 1. Under an argon atmosphere, liquid paraffin and 4,5-difluoro-2-methylphenol (liquid at room temperature, boiling point 210°C) were uniformly mixed in a volume ratio of 97:3 to obtain a mixed system;

[0128] 2. Add lithium powder to the mixed system at a solid-liquid ratio of 10:1, heat to 195°C at 5°C / min, start low-speed stirring after the temperature stabilizes, and after the temperature stabilizes at 195°C again, turn on high-speed stirring to 9000 rpm and maintain for 10 min, then stir at a low speed of 500 rpm and keep at 195°C for 30 min.

[0129] 3. After the system temperature is naturally cooled to 130°C, inject it into the filter to remove excess solvent, then transfer it to a vacuum dryer to remove excess solvent by vacuuming, and maintain vacuum at 130°C for 30 minutes.

[0130] 4. Use high-purity CO2 with a purity of 99.996% to break the vacuum, and keep the system in the CO2 atmosphere for 100 min, with the temperature controlled at 130°C. After cooling, a passivation lithium powder containing LiF, Li2CO3, lithium alcohol and organic matter in the passivation layer is obtained.

[0131] Example 5

[0132] The preparation method of the passivated lithium powder provided in this embodiment is basically the same as that in embodiment 1, except that:

[0133] Without step 4, a passivation lithium powder containing LiF, lithium alcohol and organic matter in the passivation layer is obtained.

[0134] Example 6

[0135] The preparation method of the passivated lithium powder provided in this embodiment is basically the same as that in embodiment 1, except that:

[0136] Without step 4, a passivation lithium powder containing LiF, lithium alcohol and organic matter in the passivation layer is obtained.

[0137] Example 7

[0138] The preparation method of the passivated lithium powder provided in this embodiment is basically the same as that in embodiment 1, except that:

[0139] In step 1, the volume ratio of liquid paraffin to 4-fluoro-2-isopropoxyphenol is 95:5, and a passivation lithium powder containing LiF, Li2CO3, lithium alcohol and organic matter in the passivation layer is obtained.

[0140] Example 8

[0141] The preparation method of the passivated lithium powder provided in this embodiment is basically the same as that in embodiment 1, except that:

[0142] In step 1, the volume ratio of liquid paraffin to 4,5-difluoro-2-methylphenol is 95:5, and a passivation lithium powder containing LiF, Li2CO3, lithium alcohol and organic matter in the passivation layer is obtained.

[0143] Example 9

[0144] The preparation method of the passivated lithium powder provided in this embodiment is basically the same as that in embodiment 1, except that:

[0145] In step 2, lithium powder is added to the mixed system at a solid-liquid ratio of 10:1, and the mixture is heated to 187°C at 5°C / min. After the temperature stabilizes, low-speed stirring is started. After the temperature stabilizes at 187°C again, high-speed stirring is turned on to 8000 rpm and maintained for 10 minutes, and then low-speed stirring is performed at 300 rpm and kept at 187°C for 30 minutes.

[0146] Comparative Example 1

[0147] The preparation method of the passivated lithium powder provided in this comparative example comprises the following steps:

[0148] 1. Under argon atmosphere, add liquid paraffin and lithium powder at a solid-liquid ratio of 10:1 to lithium powder, heat to 187°C at 5°C / min, and start low-speed stirring after the temperature stabilizes. After the temperature stabilizes at 187°C again, turn on high-speed stirring to 11000 rpm and keep for 10 min, then stir at a low speed of 500 rpm and keep at 187°C for 30 min.

[0149] 3. After the system temperature is naturally cooled to 130°C, the system is injected into a filter to remove excess solvent, and then transferred to a vacuum dryer to remove excess solvent by vacuuming. After maintaining the vacuum at 130°C for 30 minutes, an inert gas such as Ar is used to break the vacuum to obtain unpassivated lithium powder.

[0150] Comparative Example 2

[0151] The preparation method of the passivated lithium powder provided in this comparative example comprises the following steps:

[0152] The unpassivated lithium powder obtained in Comparative Example 1 was placed in an ALD device, and LiF was deposited on the surface of the lithium powder as a raw material to obtain an ex-situ passivated LiF-coated passivated lithium powder.

[0153] Comparative Example 3

[0154] The preparation method of the passivated lithium powder provided in this comparative example is basically the same as that of comparative example 11, except that:

[0155] In step 3, after maintaining vacuum at 130° C. for 30 min, CO 2 is used to break the vacuum to obtain ex-situ passivated Li 2 CO 3 coated passivated lithium powder.

[0156] Comparative Example 4

[0157] The preparation method of the passivated lithium powder provided in this comparative example comprises the following steps:

[0158] The unpassivated lithium powder obtained in Comparative Example 1 was placed in an ALD device, and LiF and Li2CO3 were respectively deposited on the surface of the lithium powder as raw materials to obtain non-in-situ passivated LiF and Li2CO3 coated passivated lithium powder.

[0159] Test Case

[0160] 1. The passivated lithium powder provided in all embodiments and comparative examples was tested, comprising the following steps:

[0161] 1) Particle size test: dedicated Malvern laser particle size analyzer.

[0162] 2) Passivation layer thickness test: cryo-FIB combined with SEM.

[0163] 3) Passivation layer composition test: After the above passivation lithium powder samples are prepared in a glove box, they are vacuum transferred to the XPS test chamber for XPS testing.

[0164] The specific test results are shown in Table 1.

[0165] Note: The contents of LiF, Li2CO3 and lithium alkoxide here are the proportions of the passivation layer, and the effective lithium content below is the proportion of active lithium in the entire lithium powder particles.

[0166] Table 1

[0167]

[0168] 2. Air exposure test of passivated lithium powder

[0169] The passivated lithium powder provided in all the embodiments and comparative examples was sampled in a sampling unit of 100 mg and then sealed and transferred to a constant temperature and humidity test chamber, which was set in advance to a dew point of -20°C and an air environment of 20°C. The samples were placed in the test chamber for air exposure experiments and samples were taken at different times. The test results are shown in Table 2.

[0170] 3. Effective lithium test

[0171] Weigh ~40 mg of the passivation powder provided in all embodiments and comparative examples into a special crucible, quickly place it in the cavity of a differential scanning calorimeter, and test it under an Ar protective atmosphere: the temperature rise range is 30-200°C, and the heating rate is 5°C / min. After obtaining the test curve, the melting enthalpy of the sample is obtained by integration and compared with the standard melting enthalpy of metallic lithium to obtain the effective lithium content. The test results are shown in Table 2.

[0172] 4. Passivated lithium powder lithium replenishment capacity test

[0173] The passivated lithium powders provided in all the examples and comparative examples were prepared at a concentration of 2 mg / cm 2The lithium replenishment density was evenly sprinkled on the surface of the artificial graphite negative electrode, and a force of ~10 MPa was applied to crush the lithium powder particles to release the inner layer of metallic lithium; after standing, the graphite electrode was used as the negative electrode to assemble the battery to test the lithium replenishment capacity of the passivated lithium powder. The test conditions in the capacity test were a test window of 0~0.6V and a charging current of 0.1C. The test results are shown in Table 2.

[0174] 5. Battery cycle life test after passivated lithium powder supplementation

[0175] The passivated lithium powders provided in all the examples and comparative examples were prepared at a concentration of 2 mg / cm 2 The lithium supplement density is evenly sprinkled on the surface of the artificial graphite negative electrode, and a force of ~10 MPa is applied to crush the lithium powder particles to release the inner layer of metallic lithium; after standing, the battery is assembled with the graphite electrode as the negative electrode to test the battery cycle life.

[0176] The battery prepared above was subjected to a cycle performance test at room temperature of 25°C. The test process was as follows: first, 3C constant current charging to 4.2V, then constant voltage charging with a cutoff current of 0.05C, and finally 1C constant current discharge to 2.5V. The cycle test was repeated until the capacity decayed to 80%. The test results are shown in Table 2.

[0177] Table 2

[0178]

[0179] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A passivated lithium powder, characterized in that: The passivated lithium powder comprises lithium powder and a passivation layer coated on the surface of the lithium powder; The passivation layer includes a product generated by an in-situ reaction of the compound represented by Formula 1 and the lithium powder; C n H x (OH) y F z Formula 1 In formula 1, 2≤n≤50, y≥1, z≥1, x≥1; The products include LiF and C n H x (OLi) y .

2. The passivated lithium powder according to claim 1, characterized in that: The passivation layer also includes Li2CO3.

3. The passivated lithium powder according to claim 1 or 2, characterized in that: 7≤n≤50。 4. The passivated lithium powder according to any one of claims 1 to 3, characterized in that: The compound represented by formula 1 has a melting point of ≤100°C and a boiling point of ≥220°C.

5. The passivated lithium powder according to any one of claims 1 to 4, characterized in that: The compound represented by Formula 1 includes one or more of 4-fluoro-2-isopropoxyphenol and 4,5-difluoro-2-methylphenol.

6. The passivated lithium powder according to any one of claims 1 to 5, characterized in that: The D50 particle size of the passivated lithium powder is 30 um to 60 um; And / or, the thickness of the passivation layer is 150 nm to 400 nm.

7. A method for preparing the passivated lithium powder according to any one of claims 1 to 6, characterized in that: The following steps are involved: In an argon atmosphere, the compound represented by formula 1 is mixed with an inert solvent to obtain a mixed system; lithium powder is added to the mixed system and reacted at 180° C. to 220° C. to obtain the passivated lithium powder.

8. The preparation method according to claim 7, characterized in that: The inert solvent includes liquid paraffin; And / or, the volume ratio of the inert solvent to the compound represented by Formula 1 is 70:30 to 99:1, preferably 95:5 to 98:2; And / or, the reaction is carried out under stirring conditions, and the stirring rate is 5000-20000 rpm, preferably 8000-11000 rpm; And / or, the reaction time is 0.5 to 24 hours, preferably 0.5 to 1.5 hours.

9. The preparation method according to claim 7 or 8, characterized in that: After the reaction is completed, the method further includes: cooling the temperature of the reaction system to below the melting point of metallic lithium, and then performing vacuum drying on the reaction system; The temperature of the vacuum drying treatment is ≤180°C, preferably 130-140°C.

10. The preparation method according to claim 9, characterized in that: After the vacuum drying treatment is completed, the method further comprises: introducing CO2 gas into the reaction system at a temperature of 120-179°C, preferably 130-140°C.

11. A negative electrode sheet, characterized in that: The invention comprises the passivated lithium powder according to claims 1 to 6 or the passivated lithium powder prepared by the preparation method according to any one of claims 7 to 10.

12. A battery, characterized in that: Includes the negative electrode sheet as claimed in claim 11.

13. An electrical equipment, characterized in that: Comprising the battery as claimed in claim 12.

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