CN108598365B - Negative electrode for lithium secondary battery, preparation method thereof and lithium secondary battery - Google Patents

Negative electrode for lithium secondary battery, preparation method thereof and lithium secondary battery Download PDF

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CN108598365B
CN108598365B CN201810516819.1A CN201810516819A CN108598365B CN 108598365 B CN108598365 B CN 108598365B CN 201810516819 A CN201810516819 A CN 201810516819A CN 108598365 B CN108598365 B CN 108598365B
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lithium
secondary battery
framework
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negative electrode
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CN108598365A (en
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马玉林
李昌锦
高云智
尹鸽平
刘松松
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Harbin Institute of Technology
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • 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
    • 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
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Abstract

A negative electrode for a lithium secondary battery, a preparation method thereof and the lithium secondary battery belong to the field of chemical power sources. The invention mainly comprises a convex array electrode framework, a nano-scale alloy framework and active metal lithium, wherein the material of the convex array electrode framework with large aperture is any one of Cu, Al, Sn, Fe, Co, Ni, Zn and In, the nano-scale alloy framework comprises lithium element and non-lithium element, the non-lithium element material comprises at least one of Sn, Si, Cu, In, Al, Mg, Ge, Zn and Ni, the active metal lithium is filled In the pores of the nano-scale alloy framework and is fully contacted with the nano-scale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited In the pores of the convex array electrode framework. The invention can prevent the collapse of the electrode caused by the structural damage of the nano framework in the long-term circulation process, fully inhibit the volume change of the electrode, improve the interface stability and further improve the electrochemical performance of the lithium cathode.

Description

Negative electrode for lithium secondary battery, preparation method thereof and lithium secondary battery
Technical Field
The invention belongs to the field of chemical power sources; in particular to a negative electrode for a lithium secondary battery, a preparation method thereof and the lithium secondary battery.
Background
With the development of society, the demand for secondary battery systems with higher energy density is increasingly pressing. The metal lithium has the highest specific capacity (3860mAh/g) and the most negative electrode potential (-3.045V vs. SHE) in the known negative electrode material, but the metal lithium is easy to generate complex interface reaction with the electrolyte, so that the consumption of active lithium, the dry-up of the electrolyte and the gradual increase of interface impedance are caused, and the efficiency is continuously reduced in the process of charge-discharge circulation; the uneven deposition of lithium ions on the surface of an electrode causes a large amount of lithium dendrites to be generated on the surface of the electrode, the continuously grown lithium dendrites penetrate through a battery diaphragm to be in contact with a positive electrode, so that the internal short circuit of the battery is caused, and the potential safety hazard is caused, and if the lithium dendrites are broken from the electrode to become dead lithium which loses electrochemical activity, the specific capacity of the electrode is reduced; in addition, the volume change rate of the metal lithium electrode in the charging and discharging process is large, and the gradual pulverization of the electrode is caused by the severe volume expansion and contraction. Therefore, improvement of safety and cycle stability of the lithium metal negative electrode is urgently required.
Yang et al use three-dimensional copper with a submicron skeleton as the current collector of the lithium negative electrode, reduce current density, and stabilize the lithium metal negative electrode. Kozen et Al formed Al on the surface of a lithium negative electrode with a thickness of 14nm by Atomic Layer Deposition (ALD)2O3The film inhibits the interface side reaction and the growth of lithium dendrite, but the methods are complex to prepare and high in cost.
In the patent with application number CN 201510394325.7, lithium metal powder is used as a negative electrode, the specific surface area of a powder porous electrode is high, the current density is reduced, the growth of lithium dendrites is inhibited, but during heavy-current discharge, the structural morphology of the lithium powder electrode is changed greatly, and the cycling stability is reduced. In US 4002492, Li-Al alloy is used as a negative electrode, and Li-Sn and Li-Si alloy is also used as a negative electrode to reduce the reaction activity of the negative electrode and inhibit the growth of lithium dendrite, but the volume change of the electrode is severe in the alloying-dealloying process, so that the electrode is pulverized and the service life of the battery is short.
Therefore, it is highly desirable to develop a simple method for preparing a lithium negative electrode, which improves the safety and cycle stability of a lithium metal negative electrode.
Disclosure of Invention
The invention aims to provide a negative electrode for a lithium secondary battery, a preparation method of the negative electrode and the lithium secondary battery.
The invention is realized by the following technical scheme:
the negative electrode for the lithium secondary battery mainly comprises a convex array electrode framework, a nanoscale alloy framework and active metal lithium, wherein the material of the convex array electrode framework with large aperture is any one of Cu, Al, Sn, Fe, Co, Ni, Zn and In, the nanoscale alloy framework comprises lithium elements and non-lithium elements, the non-lithium element material comprises at least one of Sn, Si, Cu, In, Al, Mg, Ge, Zn and Ni, the active metal lithium is filled In pores of the nanoscale alloy framework and is fully contacted with the nanoscale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited In the pores of the convex array electrode framework.
The negative electrode for the lithium secondary battery is characterized in that the cross section of the bulge array in the bulge array electrode framework is any one of circular, polygonal, five-pointed star and fan-shaped, the diameter of the cross section of the bulge array is 0.1-5 mu m, and the height of the cross section of the bulge array is 1-50 mu m.
According to the negative electrode for the lithium secondary battery, the non-lithium component in the lithium-rich alloy with the nanoscale alloy skeleton structure is in gradient distribution.
According to the negative electrode for the lithium secondary battery, the content of non-lithium elements in the lithium-rich alloy accounts for 10% -30% of the total amount of the lithium-rich alloy.
In the negative electrode for a lithium secondary battery according to the present invention, the active metal lithium is an excess amount of active metal lithium.
According to the negative electrode for the lithium secondary battery, the non-lithium components are distributed in a gradient manner, the non-lithium components are enriched on the surface of the electrode, and the concentration gradient reaches the maximum.
The negative electrode for the lithium secondary battery has the following advantages: the convex array electrode framework is a three-dimensional current collector (an array electrode or a foam electrode) with a large-aperture structure and is used as a carrier of the lithium-rich alloy and a support of the electrode, so that the collapse of the electrode caused by the structural damage of the nano framework in the long-term circulation process is prevented, the circulation stability of the electrode is improved, and the volume change of the electrode is fully inhibited; the lithium-rich alloy with the nano alloy skeleton structure can fully promote the uniform distribution of current in the lithium-rich alloy, effectively slow down the violent volume change of a non-lithium material in the lithium extraction and insertion process, and improve the stability of the electrode; the lithium-rich alloy with gradient distribution can effectively reduce the reactivity of the lithium cathode at the interface, improve the interface stability and further improve the electrochemical performance of the lithium cathode.
The negative electrode for a lithium secondary battery according to the present invention can be used for a lithium secondary battery, a solid-state lithium battery, and a lithium-air battery.
The invention relates to a preparation method of a negative electrode for a lithium secondary battery, which comprises the following steps:
step a, preparing a raised array electrode framework by a template method;
and b, preparing a nano-scale alloy framework and filling active metal lithium by vacuum evaporation or magnetron sputtering.
In the step a, the preparation of the porous template in the raised array electrode framework adopts a polycarbonate film with the thickness of 20 mu m, the polycarbonate film is bombarded by nuclear fission fragments to generate damage traces, and the traces are corroded into holes by chemical corrosion to prepare the porous template.
The invention relates to a preparation method of a negative electrode for a lithium secondary battery, which takes platinum as a substrate and utilizes a prepared porous template to prepare a raised array electrode framework through electrochemical deposition or a sol-gel method.
According to the preparation method of the negative electrode for the lithium secondary battery, porous copper or foam copper can be used as a raised array electrode framework.
The invention relates to a method for preparing a cathode for a lithium secondary battery, wherein in the step b, vacuum evaporation is prepared in a multi-crucible mode, pure lithium and non-lithium element particles are respectively used as evaporation sources, a substrate is a raised array electrode framework, the vacuum degree of a vacuum chamber is more than or equal to 2 multiplied by 10-2Pa, the output power of the power supply for vacuum evaporation is 50-150W, the content of non-lithium elements added into the crucible of the evaporation source is 10% -50%, the vacuum thermal evaporation time is 15-30 min, and the distance between the substrate in the vacuum evaporation chamber and the crucible of the evaporation source is 5-15 cm.
According to the preparation method of the negative electrode for the lithium secondary battery, in the step b, the magnetron sputtering is prepared in a multi-target mode, and the vacuum degree in a vacuum sputtering chamber is not less than 5 multiplied by 10-3Pa, the power output power of the magnetron sputtering instrument is 15-30W, the argon gas flow in the sputtering process is 15-25L/min, and the vacuum sputtering time is 20-60 min.
The invention relates to a preparation method of a negative electrode for a lithium secondary battery, which is characterized in that pure lithium and non-lithium element particles are respectively used as evaporation sources in vacuum evaporation, a substrate is used as an array current collector, and the structure of an evaporated lithium alloy is regulated and controlled by adjusting parameters such as the vacuum degree of an evaporation chamber, the output power, the evaporation source proportion, the evaporation time, the distance between the substrate and the evaporation sources and the like. When the gradient lithium alloy is prepared, a multi-crucible mode is adopted, evaporation sources with different element proportions are arranged in the crucible, the temperature of the crucible is controlled by controlling different output powers, so that the gradient lithium alloy with different non-lithium element content gradients is prepared at different evaporation rates.
According to the preparation method of the negative electrode for the lithium secondary battery, the magnetron sputtering adopts a magnetron sputtering instrument (the model is JCP-350M2), and the lithium-rich alloy with proper thickness is deposited on the surface of the substrate. The microstructure of the lithium-rich alloy electrode is regulated and controlled by regulating parameters such as sputtering output power, gas flow, vacuum degree, deposition time and the like. When the gradient lithium alloy is prepared, the content change of non-lithium components at different depths is controlled by adopting a multi-target mode and controlling the element content and the sputtering power in different targets.
According to the preparation method of the negative electrode for the lithium secondary battery, the gradient grading lithium-rich alloy negative electrodes with different element contents are prepared by regulating and controlling the process parameters in the evaporation or sputtering process, so that the problems of lithium dendrite and volume change of the secondary lithium battery in the circulation process are solved, and the circulation characteristic of the battery is improved.
The lithium secondary battery comprises a shell, and a negative electrode, a positive electrode, an organic electrolyte and a separation film which are arranged in the shell and used for the lithium secondary battery, wherein the negative electrode used for the lithium secondary battery comprises a convex array electrode framework, a nano-scale alloy framework and excessive active metal lithium, the active metal lithium is filled in pores of the nano-scale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited in the pores of the array electrode framework.
According to the lithium secondary battery provided by the invention, the cathode for the lithium secondary battery is a gradient graded lithium-rich alloy electrode, so that the current density is reduced, the uniform distribution of current in the lithium-rich alloy is promoted, the growth of lithium dendrite and the severe volume change of the electrode are effectively inhibited, and the interface stability and the cycling stability of the electrode are improved. Has high capacity and excellent cycle stability.
Drawings
FIG. 1 is a schematic view of a structure of a negative electrode for a lithium secondary battery;
fig. 2 is a voltage capacity curve obtained by charging a lithium electrode, which is a negative electrode and a lithium sheet, which is a counter electrode, to 1.5V prepared by the fourth embodiment;
FIG. 3 shows Li | LiFePO prepared by the fifth embodiment4A first charge-discharge capacity voltage curve of the system battery;
FIG. 4 shows Li | LiFePO prepared by the fifth embodiment4A comparison curve of the cycle performance of the discharge capacity cycle times of the system battery;
FIG. 5 is a plot of the first charge and discharge capacity voltage of a Li | KB/S system battery prepared in accordance with method six of the present embodiments;
FIG. 6 is a graph of the cycle performance versus the number of cycles of discharge capacity for a Li | KB/S system battery prepared in accordance with method six of the preferred embodiments.
FIG. 7 is a graph of cycle performance of a lithium air battery obtained by preparing a commercial negative electrode according to method eight of the embodiments;
fig. 8 is a graph showing the cycle performance of a lithium-air battery obtained by preparing a negative electrode for a lithium secondary battery according to method eight of the embodiment.
In the figure: 1 raised array electrode skeleton, 2 active metal lithium, 3 nanometer alloy skeleton.
Detailed Description
The first embodiment is as follows:
the negative electrode for the lithium secondary battery is mainly composed of a convex array electrode framework 1, a nanoscale alloy framework 3 and active metal lithium 2, wherein the material of the convex array electrode framework with large aperture is any one of Cu, Al, Sn, Fe, Co, Ni, Zn and In, the nanoscale alloy framework comprises lithium elements and non-lithium elements, the non-lithium element material comprises at least one of Sn, Si, Cu, In, Al, Mg, Ge, Zn and Ni, the active metal lithium is filled In pores of the nanoscale alloy framework and is fully contacted with the nanoscale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited In the pores of the convex array electrode framework.
In the negative electrode for a lithium secondary battery according to the present embodiment, the cross-sectional shape of the projection array in the projection array electrode skeleton is any one of a circle, a polygon, a pentagram, and a sector, the cross-sectional diameter of the projection array is 0.1 μm to 5 μm, and the cross-sectional height of the projection array is 1 μm to 50 μm.
In the negative electrode for a lithium secondary battery according to the present embodiment, the non-lithium component in the lithium-rich alloy having a nano-scale alloy skeleton structure is distributed in a gradient manner.
In the negative electrode for a lithium secondary battery according to the present embodiment, the content of the non-lithium element in the lithium-rich alloy accounts for 10% to 30% of the total amount of the lithium-rich alloy.
In the negative electrode for a lithium secondary battery according to the embodiment, the protruding array electrode skeleton is a three-dimensional current collector (an array electrode or a foam electrode) with a large-aperture structure, and is used as a carrier of a lithium-rich alloy and a support of the electrode, so that collapse of the electrode due to structural damage of the nano skeleton in a long-term circulation process is prevented, the circulation stability of the electrode is improved, and volume change of the electrode is sufficiently inhibited; the lithium-rich alloy with the nano alloy skeleton structure can fully promote the uniform distribution of current in the lithium-rich alloy, effectively slow down the violent volume change of a non-lithium material in the lithium extraction and insertion process, and improve the stability of the electrode; the lithium-rich alloy with gradient distribution can effectively reduce the reactivity of the lithium cathode at the interface, improve the interface stability and further improve the electrochemical performance of the lithium cathode.
The second embodiment is as follows:
a method for manufacturing a negative electrode for a lithium secondary battery according to a first embodiment includes the steps of:
step a, preparing a raised array electrode framework by a template method;
and b, preparing a nano-scale alloy framework and filling active metal lithium by vacuum evaporation or magnetron sputtering.
In the method for preparing the negative electrode for the lithium secondary battery according to the embodiment, the porous template in the raised array electrode framework in the step a is prepared by adopting a polycarbonate film with the thickness of 20 mu m, causing the damage trace to appear through nuclear fission fragment bombardment, and corroding the trace into holes through chemical corrosion to prepare the porous template.
In the method for preparing the negative electrode for the lithium secondary battery according to the embodiment, the vacuum evaporation in the step b is prepared in a multi-crucible mode, pure lithium particles and non-lithium element particles are respectively used as evaporation sources, the substrate is a raised array electrode framework, and the vacuum degree of the vacuum chamber is more than or equal to 2 multiplied by 10-2Pa, the output power of the power supply for vacuum evaporation is 50-150W, the content of non-lithium elements added into the crucible of the evaporation source is 10% -50%, the vacuum thermal evaporation time is 15-30 min, and the distance between the substrate in the vacuum evaporation chamber and the crucible of the evaporation source is 5-15 cm.
In the method for preparing a negative electrode for a lithium secondary battery according to the present embodiment, in step b, the magnetron sputtering is performed using a multi-target method, and a vacuum degree in a vacuum sputtering chamber is ≧ 5 × 10-3Pa, the power output power of the magnetron sputtering instrument is 15-30W, the argon gas flow in the sputtering process is 15-25L/min, and the vacuum sputtering time is 20-60 min.
In the method for preparing a negative electrode for a lithium secondary battery according to the present embodiment, pure lithium and non-lithium particles are used as evaporation sources, respectively, in vacuum evaporation, and a substrate is used as an array current collector, and the structure of an evaporated lithium alloy is controlled by adjusting parameters such as the vacuum degree of an evaporation chamber, the output power, the evaporation source ratio, the evaporation time, the distance between the substrate and the evaporation source, and the like. When the gradient lithium alloy is prepared, a multi-crucible mode is adopted, evaporation sources with different element proportions are arranged in the crucible, the temperature of the crucible is controlled by controlling different output powers, so that the gradient lithium alloy with different non-lithium element content gradients is prepared at different evaporation rates.
In the method for manufacturing a negative electrode for a lithium secondary battery according to the embodiment, a magnetron sputtering apparatus (model JCP-350M2) is used for depositing a lithium-rich alloy with a suitable thickness on the surface of a substrate. The microstructure of the lithium-rich alloy electrode is regulated and controlled by regulating parameters such as sputtering output power, gas flow, vacuum degree, deposition time and the like. When the gradient lithium alloy is prepared, the content change of non-lithium components at different depths is controlled by adopting a multi-target mode and controlling the element content and the sputtering power in different targets.
The third concrete implementation mode:
according to a specific embodiment, the lithium secondary battery comprises a casing, and a negative electrode, a positive electrode, an organic electrolyte and a separator for the lithium secondary battery, which are arranged in the casing, wherein the negative electrode for the lithium secondary battery comprises a raised array electrode framework, a nanoscale alloy framework and an excess amount of active metal lithium, the active metal lithium is filled in pores of the nanoscale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited in the pores of the array electrode framework.
According to the lithium secondary battery of the first embodiment, the provided gradient grading lithium-rich alloy negative electrode for the lithium secondary battery reduces the current density, promotes the uniform distribution of current in the lithium-rich alloy, effectively inhibits the growth of lithium dendrites and the severe volume change of the electrode, and improves the interface stability and the cycling stability of the electrode. Has high capacity and excellent cycle stability
The fourth concrete implementation mode:
according to the lithium secondary battery prepared from the negative electrode for lithium secondary battery of the first embodiment, the negative electrode for lithium secondary battery is a research electrode, a commercial lithium metal sheet is a counter electrode, and 1mol/L lithium hexafluorophosphate (LiPF)6) Ethylene Carbonate (EC) + dimethyl carbonate (DMC) (volume ratio 1:2) as electrolyte and polypropylene membrane as separator, assembled into CR2025 button cell. The battery is charged at 0.5mA/cm2The current density of (1) was charged, and the cut-off voltage was 1.5V. FIG. 2 is a voltage-capacity curve of a battery, and as shown in FIG. 2, the active lithium content of the negative electrode for a lithium secondary battery is 3.8mAh/cm2Can meet the theoretical capacity requirement of the anode material of the current lithium secondary battery system.
The fifth concrete implementation mode:
the negative electrode for the lithium secondary battery is a research electrode; the prepared lithium iron phosphate electrode is used as a positive electrode, and the preparation method of the lithium iron phosphate electrode comprises the following steps: with phosphoric acidLithium iron (LiFePO)4) Mixing the positive electrode active material with a conductive agent (Super-P) and a binder (PVDF) according to a mass ratio of 8:1:1, adding a proper amount of N-methyl-2-pyrrolidone (NMP) solvent, uniformly stirring, coating on a current collector Al foil, drying in a vacuum drying oven at 120 ℃ for 10 hours, and punching into a wafer with the diameter of 14 mm; 1mol/L lithium hexafluorophosphate (LiPF)6) Ethylene Carbonate (EC) + dimethyl carbonate (DMC) (volume ratio 1:2) as electrolyte and polypropylene membrane as separator, assembled into CR2025 button cell. The battery was first activated by charging and discharging 3 times at a rate of 0.1C (1C 170mAh/g), and then cycled at a rate of 1C with a charging and discharging voltage range of 2.5-4.2V. The first charge-discharge curve and the cycle performance curve are shown in fig. 3 and 4, respectively, and Li | LiFePO can be seen from fig. 34The first discharge capacity of the system battery was 147.4mAh/g, and Li | LiFePO can be seen from FIG. 44The capacity retention rate of the system battery after 300 times of cycling is 86.36%, while the commercial lithium sheet obviously decays after 150 times of cycling.
The sixth specific implementation mode:
the negative electrode for the lithium secondary battery is a research electrode; the prepared KB/S electrode is a positive electrode, and the preparation method of the KB/S electrode is as follows: mixing KB/S serving as a positive electrode active substance with a conductive agent (Super-P) and a binder (PVDF) according to a mass ratio of 8:1:1, adding a proper amount of N-methyl-2-pyrrolidone (NMP) solvent, uniformly stirring, coating on a current collector Al foil, drying for 10 hours in a vacuum drying oven at 120 ℃, and punching into a wafer with the diameter of 14 mm; 1mol/L lithium bistrifluoromethanesulfonylimide (LiTFSI)/ethylene glycol Dimethyl Ether (DEM) +1, 3-dioxolane ring (DOL) (volume ratio 1:1) + 1% LiNO3And (3) assembling the CR2025 button cell by taking the polypropylene film as a diaphragm as electrolyte. The cell was cycled at a rate of 0.2C (1C 1675mA/g) with a charge and discharge voltage range of 1.7-2.6V. The first charge-discharge curve and cycle performance are shown in fig. 5 and 6, and it can be seen from fig. 5 that 2 plateaus appear in the Li | KB/S system battery during the discharge process, which respectively correspond to the 2-step reaction of the sulfur anode discharge process, i.e. Li2SnAnd Li2The first discharge capacity of the Li | KB/S system battery is 1019mAh/g in the formation process of S, and can be seen from FIG. 6It can be seen that the capacity retention rate of the Li | KB/S system battery is 55% after 100 cycles, while the capacity retention rate of the commercial lithium sheet is only 42% after 100 cycles, and the cycle performance is obviously improved.
The seventh embodiment:
the negative electrode for the lithium secondary battery is a research electrode; the prepared lithium iron phosphate electrode is used as a positive electrode, and the preparation method of the lithium iron phosphate electrode comprises the following steps: with lithium iron phosphate (LiFePO)4) Mixing the positive electrode active material with a conductive agent (Super-P) and a binder (PVDF) according to a mass ratio of 8:1:1, adding a proper amount of N-methyl-2-pyrrolidone (NMP) solvent, uniformly stirring, coating on a current collector Al foil, drying in a vacuum drying oven at 120 ℃ for 10 hours, and punching into a wafer with the diameter of 14 mm; CR2025 button cells were assembled using PEO-based solid electrolyte instead of separator and electrolyte. The battery was first activated by charging and discharging 2 times at a rate of 0.1C (1C 170mAh/g), and then cycled at a rate of 1C with a charging and discharging voltage range of 2.8-4.2V. The first discharge capacity of the battery reaches 127mAh/g, the discharge capacity is still 104mAh/g after the battery is cycled for 300 times, the discharge specific capacity of the commercial pure lithium electrode is only 96mAh/g after the battery is cycled for 300 times, and the cycle performance is obviously improved.
The specific implementation mode is eight:
the negative electrode for the lithium secondary battery is a research electrode; the prepared carbon material air electrode is a positive electrode, and the preparation method of the air electrode comprises the following steps: Super-P is taken as a positive electrode active substance, is mixed with a binder (PVDF) according to the mass ratio of 9:1, is added with a proper amount of N-methyl-2-pyrrolidone (NMP) solvent, is uniformly stirred and then is coated on a foamed nickel current collector, is dried for 10 hours in a vacuum drying oven at 120 ℃, and is punched into a wafer with the diameter of 14 mm; the CR2025 button lithium air battery is assembled by using 1mol/L lithium bistrifluoromethanesulfonimide (LiTFSI)/tetraethylene glycol dimethyl ether (TEGDME) as an electrolyte and glass fiber as a diaphragm. The battery is circulated at a current density of 200mA/g, the charging and discharging capacity is limited to 500mAh/g, the cycle performance of the battery is shown in figures 7 and 8, and the comparison between figures 7 and 8 shows that the lithium-air battery adopting the commercial lithium electrode has obvious attenuation after 45 times of cycle of a discharging platform, but the lithium-air battery adopting the lithium electrode in the invention has obvious attenuation after 54 times of cycle, and the cycle performance of the battery is obviously improved.
The invention provides several lithium secondary batteries, which comprise the lithium negative pole piece of the first aspect of the invention, but are not limited to these batteries.

Claims (8)

1. A negative electrode for a lithium secondary battery, characterized in that: the negative electrode for the lithium secondary battery is composed of a convex array electrode framework, a nanoscale alloy framework and active metal lithium, wherein the convex array electrode framework is made of any one of Cu, Al, Sn, Fe, Co, Ni, Zn and In, the nanoscale alloy framework comprises lithium elements and non-lithium elements, the non-lithium element materials comprise at least one of Sn, Si, Cu, In, Al, Mg, Ge, Zn and Ni, the active metal lithium is filled In pores of the nanoscale alloy framework and is fully contacted with the nanoscale alloy framework to form a lithium-rich alloy, and the lithium-rich alloy is deposited In the pores of the convex array electrode framework;
the non-lithium components in the lithium-rich alloy are distributed in a gradient manner, the non-lithium components are enriched on the surface of the electrode, and the concentration gradient reaches the maximum; the raised array electrode framework is prepared by a template method, a porous template in the raised array electrode framework is prepared by adopting a polycarbonate film with the thickness of 20 mu m, damage marks appear on the polycarbonate film through nuclear fission fragment bombardment, and the damage marks are corroded into holes through chemical corrosion to prepare the porous template.
2. The negative electrode for a lithium secondary battery according to claim 1, characterized in that: the cross section of the bulge array in the bulge array electrode framework is any one of a circle, a polygon, a pentagram and a sector, the diameter of the cross section of the bulge array is 0.1-5 mu m, and the height of the cross section of the bulge array is 1-50 mu m.
3. The negative electrode for a lithium secondary battery according to claim 1, characterized in that: the content of non-lithium elements in the lithium-rich alloy accounts for 10-30% of the total amount of the lithium-rich alloy.
4. A method for preparing the negative electrode for a lithium secondary battery according to any one of claims 1 to 3, characterized in that: the method comprises the following steps:
step a, preparing a raised array electrode framework by a template method;
and b, preparing a nano-scale alloy framework and filling active metal lithium by vacuum evaporation or magnetron sputtering.
5. The method for producing a negative electrode for a lithium secondary battery according to claim 4, characterized in that: and (b) preparing the porous template in the raised array electrode framework in the step a by adopting a polycarbonate film with the thickness of 20 mu m, bombarding by nuclear fission fragments to enable the damage traces to appear, and corroding the traces into holes by chemical corrosion to prepare the porous template.
6. The method for producing a negative electrode for a lithium secondary battery according to claim 4, characterized in that: in the step b, the vacuum evaporation is prepared in a multi-crucible mode, pure lithium and non-lithium element particles are respectively used as evaporation sources, the substrate is a raised array electrode framework, and the vacuum degree of a vacuum chamber is more than or equal to 2 multiplied by 10-2Pa, the output power of the power supply for vacuum evaporation is 50-150W, the content of non-lithium elements added into the crucible of the evaporation source is 10% -50%, the vacuum thermal evaporation time is 15-30 min, and the distance between the substrate in the vacuum evaporation chamber and the crucible of the evaporation source is 5-15 cm.
7. The method for producing a negative electrode for a lithium secondary battery according to claim 4, characterized in that: the magnetron sputtering in the step b is prepared by adopting a multi-target mode, and the vacuum degree in a vacuum sputtering cabin is more than or equal to 5 multiplied by 10-3Pa, the power output power of the magnetron sputtering instrument is 15-30W, the argon gas flow in the sputtering process is 15-25L/min, and the vacuum sputtering time is 20-60 min.
8. A lithium secondary battery characterized in that: the lithium secondary battery comprises a shell, and a negative electrode, a positive electrode, an organic electrolyte and a separation film which are arranged in the shell and used for the lithium secondary battery, wherein the negative electrode used for the lithium secondary battery is the negative electrode in any one of claims 1 to 3 or the negative electrode prepared by the preparation method in any one of claims 4 to 7.
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