CN113957309B - Alloy, electrode and battery thereof - Google Patents

Alloy, electrode and battery thereof Download PDF

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Publication number
CN113957309B
CN113957309B CN202111585437.2A CN202111585437A CN113957309B CN 113957309 B CN113957309 B CN 113957309B CN 202111585437 A CN202111585437 A CN 202111585437A CN 113957309 B CN113957309 B CN 113957309B
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lithium
alloy
nitride
tin
metal
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CN113957309A (en
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陈海伟
王文伟
焦筱娟
朱盟
赵文翔
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Shenzhen Automotive Research Institute of Beijing University of Technology
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Shenzhen Automotive Research Institute of Beijing University of Technology
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C24/00—Alloys based on an alkali or an alkaline earth metal
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/02—Making non-ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C32/00—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • C22C32/0047—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents
    • C22C32/0068—Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ with carbides, nitrides, borides or silicides as the main non-metallic constituents only nitrides
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C26/00—Coating not provided for in groups C23C2/00 - C23C24/00
    • C23C26/02—Coating not provided for in groups C23C2/00 - C23C24/00 applying molten material to the substrate
    • 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
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/134—Electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
    • H01M4/139—Processes of manufacture
    • H01M4/1395—Processes of manufacture of electrodes based on metals, Si or alloys
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/386—Silicon or alloys based on silicon
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/387—Tin or alloys based on tin
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/40—Alloys based on alkali metals
    • H01M4/405—Alloys based on lithium
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/46—Alloys based on magnesium or aluminium
    • H01M4/463—Aluminium based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M4/36—Selection of substances as active materials, active masses, active liquids
    • H01M4/38—Selection of substances as active materials, active masses, active liquids of elements or alloys
    • H01M4/46—Alloys based on magnesium or aluminium
    • H01M4/466—Magnesium based
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/02—Electrodes composed of, or comprising, active material
    • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
    • H01M2004/027—Negative electrodes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Abstract

An alloy, an electrode and a battery thereof are disclosed, the alloy contains lithium, tin, X and nitrogen, wherein X is at least one selected from aluminum, boron, silicon and magnesium. The alloy can be used for preparing a negative electrode of a battery, is attached to a metal substrate, and obviously improves the cycle performance and interface stability of the battery.

Description

Alloy, electrode and battery thereof
Technical Field
The invention relates to the technical field of batteries, in particular to an alloy, an electrode thereof and a battery.
Background
Lithium ion batteries have been applied in large scale in the fields of portable electronic devices, electric vehicles, and the like. The current commercial negative electrode materials are graphite and lithium titanate, have the characteristics of low specific capacity and stable cycle performance, but the energy density of the negative electrode materials is gradually close to the limit due to an embedded energy storage mechanism. Therefore, in order to meet the increasing energy demand and obtain an energy storage device with high capacity and high stability, the further development of the cathode material is very important.
Lithium metal has an ultra-high theoretical capacity (3860 mAh g) as a "holy cup" material in a negative electrode material for a lithium battery-1) And a very low electrochemical potential (3.04V vs. SHE), enabling high discharge voltages and high energy densities. Scientists have studied lithium metal as a negative electrode material as early as 1913, but research on lithium metal negative electrodes is a passage because dendritic growth of lithium metal during repeated charge and discharge causes a serious safety problem. With the progress of scientific research and the urgent need for improving the energy density, the lithium metal negative electrode becomes a research hotspot again. Current research on lithium metal anodes aims at solving several key issues: (1) dendritic growth due to the non-uniform deposition behavior of lithium; (2) SEI films (solid electrolyte interface films) have poor stability; (3) side reactions between lithium metal and the electrolyte.
The lithium alloy is constructed, so that the uniform deposition of lithium can be effectively realized, the growth of lithium dendrites is inhibited, the electrochemical performance is further improved, and the safety is improved. Meanwhile, the lithium alloy has lower reactivity than lithium metal, and can reduce side reactions between the electrode and the electrolyte to some extent. In addition, the lithium alloy has a high ion diffusion coefficient of lithium, which is conducive to forming a good electrode/electrolyte interface and to achieving long cycle stability. When the alloy is formed, a skeleton structure can be generated in situ, and the mechanical stability of the cathode material can be effectively improved. For future industrialization, the preparation method of the lithium alloy is simple, and the cost burden can be reduced by forming the lithium alloy with a metal with a friendly price.
However, the conventional lithium metal battery has problems of poor cycle performance, poor interface stability, and the like.
Disclosure of Invention
According to a first aspect, in an embodiment, an alloy is provided, the alloy containing elements of lithium, tin, X, nitrogen, the X including, but not limited to, at least one of aluminum, boron, silicon, magnesium.
According to a second aspect, in an embodiment, there is provided an electrode comprising the alloy of the first aspect.
According to a third aspect, in an embodiment, there is provided a method of manufacturing the electrode of the second aspect, comprising:
a melting step, which comprises melting a mixture consisting of lithium, tin and nitride to obtain a molten alloy which is uniformly mixed;
and a pressing step, including pressing the molten alloy on at least part of the surface of the substrate to form an alloy layer, so as to obtain the electrode containing the alloy layer.
According to a fourth aspect, in an embodiment, there is provided a battery comprising the alloy of the first aspect, or the electrode of the second aspect.
According to the alloy, the electrode and the battery of the embodiment, the alloy can be used for preparing the negative electrode of the battery, is attached to a metal substrate, and obviously improves the cycle performance and the interface stability of the battery.
Drawings
Fig. 1 is a flow chart of the preparation of nitrogen-containing ultra-thin lithium-tin-X alloys (X = aluminum, boron, silicon or magnesium).
FIG. 2 is a graph showing cycle characteristics of the nitrogen-containing ultra-thin lithium-tin-aluminum alloy of example 1.
FIG. 3 is a graph of the cycle performance of the nitrogen-containing ultra-thin lithium-tin-boron alloy of example 2.
FIG. 4 is a graph of the cycle performance of the nitrogen-containing ultra-thin lithium-tin-silicon alloy of example 3.
FIG. 5 is a graph showing cycle characteristics of the nitrogen-containing ultrathin lithium-tin-magnesium alloy of example 4.
Fig. 6 is a graph of cycle performance of the ultra-thin lithium-tin-aluminum alloy of comparative example 1.
Fig. 7 is a graph of cycle performance of the ultra-thin lithium-tin-magnesium alloy of comparative example 2.
Fig. 8 is a time-voltage diagram of a symmetrical battery made of the nitrogen-containing ultra-thin lithium-tin-aluminum alloy of example 1.
Fig. 9 is a time-voltage plot of a symmetric cell made from the nitrogen-containing ultra-thin lithium-tin-boron alloy of example 2.
Fig. 10 is a time-voltage plot of a symmetric cell made from the nitrogen-containing ultra-thin lithium-tin-silicon alloy of example 3.
Fig. 11 is a time-voltage diagram of a symmetrical battery made of the ultra-thin lithium-tin-magnesium alloy containing nitrogen in example 4.
Fig. 12 is a time-voltage plot of a symmetric cell made from the ultra-thin lithium-tin-aluminum alloy of comparative example 1.
Fig. 13 is a time-voltage plot of a symmetrical cell made from the ultra-thin lithium-tin-magnesium alloy of comparative example 2.
Detailed Description
The present invention will be described in further detail with reference to the following detailed description and accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances. In some instances, certain operations related to the present application have not been shown or described in detail in order to avoid obscuring the core of the present application from excessive description, and it is not necessary for those skilled in the art to describe these operations in detail, so that they may be fully understood from the description in the specification and the general knowledge in the art.
Furthermore, the features, operations, or characteristics described in the specification may be combined in any suitable manner to form various embodiments. Also, the various steps or actions in the method descriptions may be transposed or transposed in order, as will be apparent to one of ordinary skill in the art. Thus, the various sequences in the specification and drawings are for the purpose of describing certain embodiments only and are not intended to imply a required sequence unless otherwise indicated where such sequence must be followed.
The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning.
As used herein, "room temperature" means 23 ± 2 ℃.
The lithium metal negative electrode loosens the inside of the lithium metal during a long-term plating/stripping process, and a large amount of dead lithium is accumulated, thereby causing a reduction in cycle performance. Lithium metal is very active and is in a thermodynamically unstable state with electrolyte, and reacts to generate an SEI film to prevent the reaction from continuing. However, the SEI film has poor compactness and is easy to break, so that the electrolyte and the exposed lithium continue to react, the electrolyte and the metallic lithium are excessively consumed, the coulombic efficiency is reduced, and the cycle life is shortened.
In one embodiment, the invention prepares a nitrogen-containing ultrathin lithium-tin-X alloy (X = aluminum, boron, silicon or magnesium) and applies the alloy to a solid lithium metal battery, thereby exhibiting excellent cycling stability and facilitating the commercial development of the lithium metal battery.
According to a first aspect, in an embodiment, an alloy is provided, the alloy containing elements of lithium, tin, X, nitrogen, the X including, but not limited to, at least one of aluminum, boron, silicon, magnesium. The alloy can be used for preparing a negative electrode of a battery and is attached to a metal substrate, so that the cycle performance and the interface stability of the battery are obviously improved.
In one embodiment, the alloy is composed of lithium, tin, X, nitrogen elements, the X including but not limited to at least one of aluminum, boron, silicon, magnesium.
In one embodiment, the X includes, but is not limited to, any one of aluminum, boron, silicon, magnesium.
In one embodiment, the alloy is prepared from a mixture of lithium, tin, and nitrides including, but not limited to, at least one of aluminum nitride, boron nitride, silicon nitride, and magnesium nitride.
In one embodiment, the mixture comprises the following components in percentage by mass: 90 to 99% of lithium, 0.5 to 9.5% of tin, and 0.5 to 9.5% of nitride.
In one embodiment, the mixture comprises the following components in percentage by mass: 95-96% of lithium, 2.5-3% of tin and 1-2.5% of nitride.
In one embodiment, the nitride includes, but is not limited to, any one of aluminum nitride, boron nitride, silicon nitride, and magnesium nitride.
In one embodiment, the alloy is prepared by melting a mixture of lithium, tin and nitride.
In one embodiment, the melting temperature is 200-300 ℃.
In one embodiment, the mixture of lithium, tin and nitride is heated to a melting temperature, and then kept at the melting temperature for 30-60 min to obtain a molten alloy which is uniformly mixed.
In one embodiment, the heating rate of the lithium, tin, and nitride is 5-30 ℃/min, preferably 10 ℃/min.
In one embodiment, the alloy is obtained by cooling to room temperature after obtaining a molten alloy that is uniformly mixed.
According to a second aspect, in an embodiment, there is provided an electrode comprising the alloy of the first aspect.
In one embodiment, the electrode is a negative electrode.
In one embodiment, the electrode further comprises a substrate.
In one embodiment, the substrate includes, but is not limited to, at least one of copper foil, tin-plated copper foil, copper-plated polyethylene terephthalate (PET) film, and the like.
In one embodiment, the alloy is attached to at least a portion of the surface of the substrate to form an alloy layer.
In an embodiment, the thickness of the alloy layer is 10-100 μm, preferably 20-50 μm.
According to a third aspect, in an embodiment, there is provided a method of manufacturing the electrode of the second aspect, comprising:
a melting step, which comprises melting a mixture consisting of lithium, tin and nitride to obtain a molten alloy which is uniformly mixed;
and a pressing step, including pressing the molten alloy on at least part of the surface of the substrate to form an alloy layer, so as to obtain the electrode containing the alloy layer.
In one embodiment, the melting temperature is 200-300 ℃.
In one embodiment, the mixture is maintained at the melting temperature for 30-60 min. The holding time includes, but is not limited to, 30min, 40min, 50min, 60 min.
In one embodiment, the lithium, tin and nitride are heated to a melting temperature, and then kept at the melting temperature for 30-60 min to obtain a molten alloy which is uniformly mixed.
In one embodiment, after pressing the molten alloy on at least a portion of the surface of the substrate, cooling to room temperature results in an electrode comprising the alloy layer.
In an embodiment, the thickness of the alloy layer is 10-100 μm.
In one embodiment, the substrate includes, but is not limited to, at least one of copper foil, tin-plated copper foil, copper-plated polyethylene terephthalate (PET) film, and the like.
According to a fourth aspect, in an embodiment, there is provided a battery comprising the alloy of the first aspect, or the electrode of the second aspect.
In one embodiment, the battery comprises a lithium battery.
In one embodiment, the lithium battery includes, but is not limited to, at least one of a button cell, a cylindrical battery, a pouch cell, and a prismatic aluminum can battery.
In one embodiment, the present invention provides a nitrogen-containing ultra-thin lithium-tin-X alloy, wherein X = aluminum, boron, silicon or magnesium, to develop a lithium metal battery with high cycling stability and rate capability. The melting method is used for obtaining the ternary alloy material with uniformly distributed lithium, tin, X and nitrogen, wherein the lithium nitride has higher ionic conductivity, can provide rapid ion transmission and is stable to lithium metal, and the improvement of interface stability is facilitated. Meanwhile, the three-dimensional lithium-tin-X alloy generated by the in-situ reaction can provide abundant lithium deposition sites, so that the cycling stability is improved.
In one embodiment, a nitrogen-containing ultra-thin lithium-tin-X alloy (X = aluminum, boron, silicon, or magnesium) is prepared by first melting lithium metal, tin metal, and nitrides (including aluminum nitride, boron nitride, silicon nitride, and magnesium nitride) and then pressing the uniform molten metal onto a copper foil as shown in fig. 1. The preparation method comprises the following specific steps:
(1) under the high-purity argon environment, according to the following formula (90-99): (0.5-9.5): (0.5-9.5) accurately weighing metal lithium, metal tin and nitride (including aluminum nitride, boron nitride, silicon nitride and magnesium nitride) according to the mass ratio, and placing the metal lithium, the metal tin and the nitride in a stainless steel container;
(2) placing the stainless steel container on a heating plate, heating to 200-300 ℃ at a heating rate of 10 ℃/min, and keeping for 30-60 minutes to obtain uniformly mixed molten metal;
(3) dipping the copper block with the molten metal, pressing the molten metal on a copper foil, and naturally cooling to room temperature to obtain the nitrogen-containing ultrathin lithium-tin-X alloy (X = aluminum, boron, silicon or magnesium) with the thickness of 10-100 mu m.
In one embodiment, three groups of materials of lithium, tin and nitride (including aluminum nitride, boron nitride, silicon nitride or magnesium nitride) are selected, and the uniformly mixed nitrogen-containing ternary lithium-tin-X alloy material can be obtained through simple melting, wherein X = aluminum, boron, silicon or magnesium. Meanwhile, the lithium nitride generated by the reaction of the nitride and the lithium has ultrahigh ionic conductivity. The molten alloy material has good fluidity, and can be dipped and pressed by a copper block to obtain an ultrathin alloy material and can also be prepared on a large scale by a blade coating process.
In one embodiment, the ratio of the three components directly affects the electrochemical performance of the lithium metal battery. The ternary lithium-tin-X alloy reduces the reactivity of lithium and suppresses side reactions with the electrolyte, resulting in a stable lithium/electrolyte interface. The lithium nitride uniformly distributed in the alloy can improve the ionic conductivity of the electrode. The excessive doping reduces the capacity and energy density of the lithium metal battery, so that an appropriate compounding ratio is important.
In one embodiment, the temperature rise rate, the holding temperature and the heat preservation time during melting metal can affect the uniformity of metal distribution in the alloy, and the uniform metal distribution is beneficial to ensuring uniform potential distribution, so that the uniform deposition of lithium in the electroplating process is realized.
In one embodiment, the invention melts three materials of metal lithium, metal tin and nitride (including aluminum nitride, boron nitride, silicon nitride or magnesium nitride) according to a certain proportion by a simple melting method, and performs in-situ alloying reaction to obtain a three-dimensional alloy structure with lithium, tin and X uniformly distributed, wherein X = aluminum, boron, silicon or magnesium, and lithium nitride generated in situ by silicon nitride and metal lithium has ultrahigh ionic conductivity, so that rapid ion transmission can be provided and the lithium metal nitride can be used as a protective material of metal lithium. This unique three-dimensional structure can provide uniform sites for lithium deposition, increase ion transport speed, and maintain excellent mechanical stability during repeated plating/stripping. Meanwhile, the synergistic effect between the lithium-tin alloy and the lithium-X alloy can promote ion transmission, so that the electrochemical performance is improved. In addition, the ultrathin lithium-tin-X alloy reduces the using amount of lithium, reduces the cost and improves the utilization rate of the lithium. The prepared ultrathin lithium-tin-silicon alloy is applied to lithium metal batteries and soft package batteries, so that the electrochemical performance and safety performance are greatly improved, and the large-scale production is hopeful to realize by uniformly coating the molten lithium alloy on the copper foil by a blade coating method.
Example 1
In a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 95: 2.5: 2.5, accurately weighing the metal lithium, the metal tin and the aluminum nitride, placing the metal lithium, the metal tin and the aluminum nitride in a stainless steel container, heating to 250 ℃, and keeping the temperature for 30-60 min (30 min in the embodiment) to obtain the molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain the nitrogen-containing ultrathin lithium-tin-aluminum alloy, and cutting to obtain a circular pole piece with the diameter of 12 mm and the thickness of about 20-50 mu m, namely the nitrogen-containing ultrathin lithium-tin-aluminum alloy.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: mixed solvent of diethyl carbonate =1:1 (volume ratio)Stirring and dissolving to obtain a solution with the concentration of 1.3mol/L (namely the concentration of lithium hexafluorophosphate in the solution is 1.3 mol/L), then adding 1, 3-dioxolane monomer into the solution, wherein the volume fraction of the 1, 3-dioxolane monomer is 30% (namely the volume of the 1, 3-dioxolane monomer accounts for 30% of the volume of the final mixed solution), and then uniformly mixing. The above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell in a dry box using a nitrogen-containing ultra-thin lithium-tin-aluminum alloy for the negative electrode and commercial lithium iron phosphate for the positive electrode. And sealing the battery and standing for 2 days to obtain the solid battery. FIG. 2 shows that the solid-state battery is at 0.1A · g-1、0.5 A·g-1Current density of (c). At 0.1 A.g-1And 0.5 A.g-1The capacity retention rates after 100 cycles are 84.25% and 80.47%, respectively, and the high capacity retention rate after 100 cycles can be seen.
Example 2
In a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 95: 2.5: 2.5, accurately weighing the metal lithium, the metal tin and the boron nitride, placing the metal lithium, the metal tin and the boron nitride in a stainless steel container, and heating the mixture to 250 ℃ to obtain the molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain a nitrogenous ultrathin lithium-tin-boron alloy, and cutting to obtain a circular pole piece with the diameter of 12 mm, namely the nitrogenous ultrathin lithium-tin-aluminum alloy.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: diethyl carbonate =1:1, and the mixed solvent is stirred and dissolved to obtain a solution with a concentration of 1.3mol/L (i.e., the concentration of lithium hexafluorophosphate in the solution is 1.3 mol/L), and then 1, 3-dioxolane monomer is added to the solution with a volume fraction of 30% (i.e., the volume of 1, 3-dioxolane monomer accounts for 30% of the volume of the final mixed solution), and then the mixture is mixed uniformly. The above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell in a dry box using a nitrogen-containing ultra-thin lithium-tin-boron alloy for the negative electrode and commercial lithium iron phosphate for the positive electrode. Then sealing the batteryAnd standing for 2 days to obtain the solid-state battery. FIG. 3 shows that the solid-state battery is at 0.1A · g-1、0.5 A·g-1Current density of (c). At 0.1 A.g-1And 0.5 A.g-1The capacity retention after 100 cycles was 84.13% and 77.85%, respectively, at the current density of (1). It can be seen that it has a higher capacity retention after 100 cycles.
Example 3
In a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 96: 3: 1, accurately weighing the metal lithium, the metal tin and the silicon nitride, placing the metal lithium, the metal tin and the silicon nitride in a stainless steel container, and heating the container to 250 ℃ to obtain the molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain the nitrogen-containing ultrathin lithium-tin-silicon alloy, and cutting to obtain a circular pole piece with the diameter of 12 mm, namely the nitrogen-containing ultrathin lithium-tin-aluminum alloy.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: diethyl carbonate =1:1 (volume ratio) was dissolved in the mixed solvent with stirring to obtain a solution concentration of 1.3mol/L (i.e., the concentration of lithium hexafluorophosphate in the solution was 1.3 mol/L), and then 1, 3-dioxolane monomer was added to the solution in a volume fraction of 30% (i.e., the volume of 1, 3-dioxolane monomer accounted for 30% of the volume of the final mixed solution), followed by mixing uniformly. The above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell in a dry box using a nitrogen-containing ultra-thin lithium-tin-silicon alloy for the negative electrode and commercial lithium iron phosphate for the positive electrode. And sealing the battery and standing for 2 days to obtain the solid battery. FIG. 4 shows that the solid-state battery is at 0.1A · g-1、0.5 A·g-1Current density of (c). At 0.1 A.g-1And 0.5 A.g-1The capacity retention after 100 cycles was 83.10% and 72.86%, respectively, at the current density of (1). It can be seen that it has a higher capacity retention after 100 cycles.
Example 4
In a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 96: 3: 1, accurately weighing metal lithium, metal tin and magnesium nitride, placing the metal lithium, the metal tin and the magnesium nitride in a stainless steel container, and heating the metal lithium, the metal tin and the magnesium nitride to 250 ℃ to obtain a molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain a nitrogenous ultrathin lithium-tin-magnesium alloy, and cutting to obtain a circular pole piece with the diameter of 12 mm, namely the nitrogenous ultrathin lithium-tin-aluminum alloy.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: diethyl carbonate =1:1 (volume ratio) was dissolved in the mixed solvent with stirring to obtain a solution concentration of 1.3mol/L (i.e., the concentration of lithium hexafluorophosphate in the solution was 1.3 mol/L), and then 1, 3-dioxolane monomer was added to the solution in a volume fraction of 30% (i.e., the volume of 1, 3-dioxolane monomer accounted for 30% of the volume of the final mixed solution), followed by mixing uniformly. In a dry box, the anode used a nitrogen-containing ultra-thin lithium-tin-magnesium alloy and the cathode used commercial lithium iron phosphate, and the above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell. And sealing the battery and standing for 2 days to obtain the solid battery. FIG. 5 shows that the solid-state battery is at 0.1A · g-1、0.5 A·g-1Current density of (c). At 0.1 A.g-1And 0.5 A.g-1The capacity retention after 100 cycles was 85.96% and 79.90%, respectively, at the current density of (1). It can be seen that it has a higher capacity retention after 100 cycles.
Comparative example 1
To demonstrate the effect of nitrogen doping on the performance of ultra-thin alloy materials, this comparative example prepared an ultra-thin lithium-tin-aluminum alloy as control sample 1. The specific preparation method is the same as that of example 1, except that aluminum nitride is replaced by metallic aluminum. The method comprises the following specific steps:
in a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 95: 2.5: 2.5, accurately weighing the metal lithium, the metal tin and the metal aluminum, placing the metal lithium, the metal tin and the metal aluminum in a stainless steel container, and heating the metal lithium, the metal tin and the metal aluminum to 250 ℃ to obtain the molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain ultrathin lithium-tin-aluminum alloy, and cutting to obtain a pole piece with the thickness of 12 mm.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: diethyl carbonate =1:1 (volume ratio) was dissolved in the mixed solvent with stirring to obtain a solution concentration of 1.3mol/L (i.e., the concentration of lithium hexafluorophosphate in the solution was 1.3 mol/L), and then 1, 3-dioxolane monomer was added to the solution in a volume fraction of 30% (i.e., the volume of 1, 3-dioxolane monomer accounted for 30% of the volume of the final mixed solution), followed by mixing uniformly. The above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell in a dry box using ultra-thin lithium-tin-aluminum alloy for the negative electrode and commercial lithium iron phosphate for the positive electrode. And sealing the battery and standing for 2 days to obtain the solid battery. FIG. 6 shows that the solid-state battery is at 0.1A · g-1Current density of (c). At 0.1 A.g-1The capacity retention after 100 cycles was 78.34%. The capacity retention rate after 100 cycles is lower than that of the examples 1-4.
Comparative example 2
To demonstrate the effect of nitrogen doping on the performance of the ultra-thin alloy material, an ultra-thin lithium-tin-magnesium alloy was prepared in this comparative example as control sample 2. The specific preparation method was the same as in example 4 except that magnesium nitride was replaced with magnesium metal. The method comprises the following specific steps:
in a glove box (argon atmosphere, water and oxygen content below 10 ppm) at 96: 3: 1, accurately weighing metal lithium, metal tin and metal magnesium, placing the metal lithium, the metal tin and the metal magnesium in a stainless steel container, and heating the metal lithium, the metal tin and the metal magnesium to 250 ℃ to obtain a molten alloy which is uniformly mixed. Uniformly dipping molten metal in a copper block, pressing the copper block on copper foil, cooling to room temperature to obtain an ultrathin lithium-tin-magnesium alloy, and cutting to obtain a pole piece with the thickness of 12 mm.
All operations for manufacturing the solid-state battery are carried out in the glove box, and the specific operation flow is as follows: adding lithium hexafluorophosphate to ethylene carbonate: dissolving diethyl carbonate =1:1 (volume ratio) in mixed solvent by stirring, and preparingThe concentration of the solution is 1.3mol/L (namely the concentration of lithium hexafluorophosphate in the solution is 1.3 mol/L), then the 1, 3-dioxolane monomer is added into the solution, the volume fraction of the 1, 3-dioxolane monomer is 30 percent (namely the volume of the 1, 3-dioxolane monomer accounts for 30 percent of the volume of the final mixed solution), and then the mixture is mixed uniformly. In a dry box, the anode used an ultra-thin lithium-tin-magnesium alloy and the cathode used commercial lithium iron phosphate, and the above solution containing 1, 3-dioxolane monomer and lithium hexafluorophosphate was added to the assembled cell. And sealing the battery and standing for 2 days to obtain the solid battery. FIG. 7 shows that the solid-state battery is at 0.1A · g-1Current density of (c). At 0.1 A.g-1The capacity retention ratio after 100 cycles was 79.57%. The capacity retention rate after 100 cycles is lower than that of the examples 1-4. The cycle performance graph shows that the interface stability of the batteries of the embodiments is better.
Interface stability may also be reflected by the polarization voltage in a symmetric cell.
The preparation method of the symmetrical battery comprises the following steps: in the glove box, the battery is assembled in sequence according to the sequence of a positive electrode shell, nitrogen-containing ultrathin lithium-tin-X alloy (X aluminum, boron, silicon and magnesium), a diaphragm, a nitrogen-containing ultrathin lithium-tin-X alloy (X aluminum, boron, silicon and magnesium), a gasket, a spring sheet and a negative electrode shell, wherein the electrolyte is commercial electrolyte, and the solute in the electrolyte is LiPF6FEC (Fluoroethylene carbonate), a solvent is a mixed solution of EC (ethylene carbonate) and DMC (dimethyl carbonate), and EC: DMC =1:1, LiPF in electrolyte6The concentration of (3) is 1.0mol/L, and the mass percentage concentration of FEC is 5%.
As can be seen from fig. 8 to 11, the voltage was kept stable and the fluctuation was small under the constant current charging and discharging for 100 hours, which indicates that the alloy materials prepared in examples 1 to 4 had good interface stability.
As can be seen from fig. 12 and 13, the voltage fluctuates greatly under the constant current charge and discharge for 100 hours, which indicates that the alloy materials prepared in comparative examples 1 and 2 have poor interface stability.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.

Claims (7)

1. The alloy is characterized by being prepared from a mixture consisting of lithium, tin and nitride, wherein the nitride is selected from at least one of aluminum nitride, boron nitride, silicon nitride and magnesium nitride, and the mixture comprises the following components in percentage by mass: 90 to 99% of lithium, 0.5 to 9.5% of tin, and 0.5 to 9.5% of nitride.
2. The alloy of claim 1, wherein the mixture comprises, in mass percent: 95-96% of lithium, 2.5-3% of tin and 1-2.5% of nitride;
the nitride is selected from any one of aluminum nitride, boron nitride, silicon nitride and magnesium nitride;
the alloy is prepared by melting a mixture consisting of lithium, tin and nitride;
the melting temperature is 200-300 ℃;
heating a mixture consisting of lithium, tin and nitride to a melting temperature, and keeping the mixture at the melting temperature for 30-60 min to obtain a uniformly mixed molten alloy;
heating the lithium, tin and nitride at a heating rate of 5-30 ℃/min;
and cooling to room temperature after obtaining the uniformly mixed molten alloy, thus obtaining the alloy.
3. An electrode comprising the alloy according to any one of claims 1 to 2.
4. The electrode of claim 3, wherein the electrode is a negative electrode;
the electrode further comprises a substrate;
the substrate comprises at least one of a copper foil, a tinned copper foil, and a copper-plated polyethylene terephthalate film;
the alloy is attached to at least part of the surface of the substrate to form an alloy layer;
the thickness of the alloy layer is 10-100 mu m.
5. A method of preparing an electrode according to claim 3 or 4, comprising:
a melting step, which comprises melting a mixture consisting of lithium, tin and nitride to obtain a molten alloy which is uniformly mixed;
and a pressing step, including pressing the molten alloy on at least part of the surface of the substrate to form an alloy layer, so as to obtain the electrode containing the alloy layer.
6. The method according to claim 5, wherein the melting temperature is 200 to 300 ℃;
heating lithium, tin and nitride to a melting temperature, and keeping the temperature at the melting temperature for 30-60 min to obtain a uniformly mixed molten alloy;
pressing the molten alloy on at least part of the surface of a substrate, and cooling to room temperature to obtain an electrode containing the alloy layer;
the thickness of the alloy layer is 10-100 mu m;
the substrate comprises at least one of a copper foil, a tin-plated copper foil, and a copper-plated polyethylene terephthalate film.
7. A battery comprising an alloy according to any one of claims 1 to 2, or an electrode according to claim 3 or 4.
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CN106086703A (en) * 2016-06-02 2016-11-09 新昌县儒岙晨辉不锈钢制品厂 A kind of cutlery stainless steel material and preparation method thereof
CN113493887A (en) * 2021-06-25 2021-10-12 天津中能锂业有限公司 Method for non-crystallizing surface of metal lithium strip, product and application thereof
CN113506872A (en) * 2021-06-25 2021-10-15 南京同宁新材料研究院有限公司 Lithium metal negative electrode material and preparation method and application thereof

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104907498A (en) * 2015-04-23 2015-09-16 苏州劲元油压机械有限公司 Casting technology of hydraulic valve
CN106086703A (en) * 2016-06-02 2016-11-09 新昌县儒岙晨辉不锈钢制品厂 A kind of cutlery stainless steel material and preparation method thereof
CN113493887A (en) * 2021-06-25 2021-10-12 天津中能锂业有限公司 Method for non-crystallizing surface of metal lithium strip, product and application thereof
CN113506872A (en) * 2021-06-25 2021-10-15 南京同宁新材料研究院有限公司 Lithium metal negative electrode material and preparation method and application thereof

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