CN113782749A - Cathode for all-solid-state battery, preparation method of cathode and all-solid-state battery - Google Patents

Cathode for all-solid-state battery, preparation method of cathode and all-solid-state battery Download PDF

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CN113782749A
CN113782749A CN202110977731.1A CN202110977731A CN113782749A CN 113782749 A CN113782749 A CN 113782749A CN 202110977731 A CN202110977731 A CN 202110977731A CN 113782749 A CN113782749 A CN 113782749A
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layer
solid
current collector
lithium storage
lithium
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CN113782749B (en
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李瑞杰
黄海强
王磊
陈少杰
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Svolt Energy Technology Wuxi Co Ltd
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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
    • H01M4/64—Carriers or collectors
    • H01M4/66—Selection of materials
    • H01M4/665—Composites
    • H01M4/667—Composites in the form of layers, e.g. coatings
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/058—Construction or manufacture
    • 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
    • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
    • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
    • 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
    • H01M4/64—Carriers or collectors
    • H01M4/70—Carriers or collectors characterised by shape or form
    • H01M4/80—Porous plates, e.g. sintered carriers
    • 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
    • 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
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Abstract

The invention provides a cathode for an all-solid-state battery, a preparation method of the cathode and the all-solid-state battery. The negative electrode for an all-solid battery includes: from the bottom up sets gradually the mass flow body, induction layer, lithium storage layer, and the porosity of the mass flow body is less than 0.1%, and lithium storage layer is porous conducting layer, and the porosity of porous conducting layer is greater than the porosity of the mass flow body. The porosity of the current collector of the negative electrode for the all-solid-state battery is small, so that the compressive capacity of the current collector is high, the requirement of the all-solid-state battery can be met, and the porosity of the lithium storage layer is controlled to be larger than the porosity of the current collector so as to meet the requirement of lithium storage. The structure of the cathode for the all-solid-state battery is simple, the cathode is convenient to apply to the all-solid-state battery, damage of lithium dendrites to a solid electrolyte layer can be effectively avoided, the service life of the all-solid-state battery is effectively prolonged, and the stability and the safety of the all-solid-state battery are guaranteed.

Description

Cathode for all-solid-state battery, preparation method of cathode and all-solid-state battery
Technical Field
The invention relates to the field of all-solid batteries, in particular to a cathode for an all-solid battery, a preparation method of the cathode and the all-solid battery.
Background
With the rapid development of consumer electronics and electric vehicles, the demands for energy density, safety, reliability and service life of batteries are increasing dramatically. Lithium metal has extremely high theoretical specific capacity (3860mAh/Kg) and lowest potential (-3.04V), so that the lithium metal secondary battery is the preferred system of the next generation of high-energy-density energy storage devices.
However, since lithium metal has high reactivity, lithium dendrite is easily formed on a lithium negative electrode, and dendrite growth is one of fundamental problems affecting safety and stability of a lithium ion battery, and thus development of the lithium battery is limited to some extent. Currently, the negative electrode of a lithium metal secondary battery directly uses a current collector as a site for lithium deposition, so that lithium ions are directly deposited on the current collector to form metallic lithium. The method does not adopt any preventive protection measures for the lithium dendrites, and therefore, the growth of the lithium dendrites is not inhibited easily, and the battery is short-circuited due to the fact that the battery diaphragm is punctured. Meanwhile, the reaction between the lithium metal deposited on the negative electrode and the solid electrolyte may increase the internal impedance of the battery, which may affect the cycle performance and rate performance of the battery. The solid electrolyte layer has many voids, which are easily penetrated by lithium dendrites during cycling, resulting in micro short circuits of the battery and reduced cycle life of the battery. In addition, lithium metal has large volume expansion and contraction phenomena in the charging and discharging processes, which can cause mechanical damage to the solid electrolyte layer in direct contact with the lithium metal, and finally the electrolyte layer generates cracks due to mechanical stress, thus irreversible damage is formed to the battery.
Based on this, researchers have attempted to suppress the growth of lithium dendrites by adding a protective layer outside the deposited lithium. The first method is to prepare an alloy protective layer on the surface of the cathode side by a liquid phase method, and coat the solution prepared by inorganic powder such as indium chloride, aluminum nitride and the like on the surface of lithium deposition to react to generate an alloy layer. In the method, the solvent reacts with lithium metal to introduce various impurities, so that the impedance of the whole battery is increased, and the reaction degree of different batches is different, so that the consistency of the alloy protective layer is poor. The second method is to use a polymer film as a protective layer on the negative electrode side, and to use a polymer film made of a polymer such as PEO, PVDF, PAN, etc. and a lithium salt, but the polymer film generally has poor mechanical strength, is difficult to block penetration of lithium dendrites, and does not contribute much to the extension of the cycle life of the battery.
For this reason, there is a need to find a simpler and more effective protection strategy against lithium dendrite growth to ensure that the battery does not have lithium dendrites to penetrate the electrolyte layer during cycling.
Disclosure of Invention
The invention mainly aims to provide a negative electrode for an all-solid-state battery, a preparation method of the negative electrode and the all-solid-state battery, and aims to solve the problem that the influence of lithium dendrite cannot be effectively solved in the prior art.
In order to achieve the above object, according to one aspect of the present invention, there is provided an anode for an all-solid battery including: from the bottom up sets gradually the mass flow body, induction layer, lithium storage layer, and the porosity of the mass flow body is less than 0.1%, and lithium storage layer is porous conducting layer, and the porosity of porous conducting layer is greater than the porosity of the mass flow body.
Further, the current collector is a metallic current collector, and preferably, the metal of the metallic current collector is selected from one of copper, nickel and stainless steel.
Further, the inducing substance used by the inducing layer is selected from one or more of Ag, In, Zn, Sn, Al, Au, Pt and Mg.
Further, the thickness of the inducing layer is 10-100 nm.
Furthermore, the porosity of the lithium storage layer is 20-70%.
Further, the conductive framework of the lithium storage layer includes carbon.
Further preferably, the thickness of the lithium storage layer is 5 to 10 μm.
In order to achieve the above object, according to one aspect of the present invention, there is provided a method of preparing an anode for an all-solid battery, the method comprising: step S1, arranging an inducing substance on the surface of the current collector to obtain an inducing layer; step S2 of disposing a lithium storage material precursor on the inducing layer, the lithium storage material precursor including an electron conductor material and a sacrificial agent; step S3, removing the sacrificial agent, and forming a porous lithium storage layer on the inducing layer, wherein the porosity of the current collector is less than 0.1%, and the porosity of the lithium storage layer is greater than the porosity of the current collector.
Further, the current collector is a metallic current collector, and preferably, the metal of the metallic current collector is selected from one of copper, nickel and stainless steel.
Further, the inducing substance is selected from one or more of Ag, In, Zn, Sn, Al, Au, Pt and Mg;
further, the thickness of the inducing layer is 10-100 nm;
further, in step S2, the inducing substance is deposited on the surface of the current collector to obtain the inducing layer, and the inducing substance is further preferably deposited on the surface of the current collector by vacuum evaporation or magnetron sputtering.
Further, step S2 deposits a lithium storage material precursor on the inducing layer, preferably by co-sputtering; the electronic conductor material comprises carbon, the sacrificial agent is elemental sulfur, and preferably, in step S3, the sacrificial agent is removed by heating, preferably, the heating temperature is 95-110 ℃.
Further, the volume ratio of the electronic conductor material to the sacrificial agent is 8: 2-3: 7.
Further, the thickness of the lithium storage layer is 5-10 μm.
According to another aspect of the present invention, there is provided an all-solid battery including a positive electrode, a negative electrode, and an electrolyte, the negative electrode including the negative electrode for an all-solid battery according to any one of the above-described embodiments of the present invention or the negative electrode for an all-solid battery prepared by any one of the preparation methods of the present application.
By applying the technical scheme of the invention, the porosity of the current collector of the cathode for the all-solid-state battery is smaller, so that the pressure resistance of the current collector is stronger, the requirement of the all-solid-state battery can be met, and the porosity of the lithium storage layer is controlled to be larger than the porosity of the current collector so as to meet the requirement of lithium storage of the current collector. The lithium storage layer for storing and depositing lithium is constructed in the cathode of the all-solid-state battery, and the lithium ions are induced to deposit and store in the lithium storage layer through the inducing layer, so that the battery short circuit caused by disordered growth of lithium dendrites is prevented. In addition, the negative electrode structure can isolate deposited lithium from the solid electrolyte layer, so that mechanical damage to the solid electrolyte layer due to volume change caused by deposition and stripping of lithium is avoided. And the structure of the cathode for the all-solid-state battery is simpler, and the cathode is convenient to apply to the all-solid-state battery.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 shows a schematic structural view of a negative electrode for an all-solid battery of the present invention;
FIG. 2 is a schematic view showing the structure of a lithium storage layer in example 1 of the present invention;
FIG. 3 shows a time-voltage diagram of a charge-discharge cycle test in example 1 of the present invention;
FIG. 4 shows a time-voltage diagram of the charge-discharge cycle test in comparative example 1 of the present invention;
fig. 5 shows a time-voltage diagram of the charge-discharge cycle test in comparative example 2 of the present invention.
Wherein the figures include the following reference numerals:
1. a current collector; 2. an inducing layer; 3. and a lithium storage layer.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.
As analyzed by the background of the present application, prior art solutions do not effectively address the lithium dendrite effect. The research shows that when the lithium of the negative electrode is stored in the three-dimensional cavity, the damage of the lithium dendrite to the solid electrolyte can be effectively prevented. However, since the all-solid-state battery has a high requirement on the compression resistance of the positive electrode, the negative electrode and the solid electrolyte, the current collector of the negative electrode is usually a dense conductive material, such as metal, which has no pores capable of storing lithium. The inventors of the present invention tried to form a lithium storage layer having three-dimensional pores on a current collector for the purpose of storing lithium using the three-dimensional pores, but found in practice that the lithium storage effect is not ideal, lithium ions are difficult to enter the three-dimensional pores as intended, and tried to provide an inducing layer between the current collector and the lithium storage layer in order to further induce the lithium ions to enter the three-dimensional pores. Through the continuous exploration of the tests, the application provides a cathode for an all-solid-state battery, a preparation method of the cathode and the all-solid-state battery.
In an exemplary embodiment of the present application, there is provided an anode for an all-solid battery, as shown in fig. 1, including: from the bottom up sets gradually and collects body 1, induction layer 2 and store up lithium layer 3, and the porosity of the body 1 that collects is less than 0.1%, stores up lithium layer 3 and is porous conducting layer, and the porosity of porous conducting layer is greater than the porosity of the body 1 that collects.
As can be seen from the above description, the current collector 1 of the negative electrode for all-solid-state battery of the present application has a small porosity, so that the compressive capacity thereof is strong, and the requirement of all-solid-state battery can be satisfied, and the porosity of the lithium storage layer 3 is controlled to be greater than the porosity of the current collector 1, so as to satisfy the requirement of lithium storage thereof. The lithium storage layer 3 for storing and depositing lithium is constructed in the cathode of the all-solid-state battery, and the lithium ions are induced to be deposited and stored in the lithium storage layer 3 through the inducing layer 2, so that the battery short circuit caused by disordered growth of lithium dendrites is prevented, and the cycle life is effectively prolonged. In addition, the negative electrode structure can isolate deposited lithium from the solid electrolyte layer, so that mechanical damage to the solid electrolyte layer due to volume change caused by deposition and stripping of lithium is avoided. And the structure of the cathode for the all-solid-state battery is simpler, and the cathode is convenient to apply to the all-solid-state battery.
In order to improve the hardness of the current collector and meet the assembly requirement of the all-solid-state battery, the current collector 1 of the present application is made of a denser material, for example, the porosity of the current collector is controlled to be less than 0.1%. In some embodiments, to reduce cost and simplify the structure of the current collector 1, the current collector 1 is a metallic current collector, such as a metallic current collector made of metals including, but not limited to, copper, nickel, and stainless steel.
In some embodiments of the present invention, the inducing material is a metal capable of alloying with lithium ions, and the lithium intercalation potential thereof should be >0.2v (vs li), because lithium ions can preferentially alloy with the material with higher lithium intercalation potential, so that lithium ions are preferentially deposited on the inducing layer 2, and the inducing material used for the inducing layer 2 includes, but is not limited to Ag, In, Zn, Sn, Al, Au, Pt, Mg. In order to increase the energy density of the entire battery, the thickness of the inducing layer 2 should be reduced as much as possible, and the thickness of the inducing layer 2 is preferably 10 to 100nm, more preferably 30 to 70nm, such as 10nm, 20nm, 30nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 80nm, 90nm, and 100 nm. The inducing layer 2 functions to induce lithium metal to be preferentially deposited thereon and then to be deposited in the lithium storage layer 3, thereby inducing deposition of lithium starting from the interface of the inducing layer 2 and the lithium storage layer 3 and growing upward, so that lithium is deposited in the pores of the lithium storage layer 3. The inducing layer 2 plays a role of inducing lithium metal to be preferentially deposited thereon, and does not serve as a lithium storage space.
The pores of the lithium storage layer 3 provide space for the growth of lithium metal, and the compressive capacity of the lithium storage layer is limited due to the existence of the pores, and in some embodiments of the invention, the porosity of the lithium storage layer 3 is controlled to be 20-70%; or the thickness of the lithium storage layer is controlled to be 5-10 mu m, or the above aspects are cooperatively controlled, so that the lithium storage capacity is improved as much as possible, and the compressive capacity is improved as much as possible. In order to enable lithium ions to be deposited with ready access to electrons on the framework of the lithium storage layer, it is preferred that the conductive framework of the lithium storage layer comprises carbon.
In another exemplary embodiment of the present invention, there is also provided a method of manufacturing an all-solid-state battery, the method including: step S1, disposing an inducing substance on the surface of the current collector to obtain an inducing layer 2; step S2 of disposing a lithium storage material precursor on the inducing layer 2, the lithium storage material precursor including an electron conductor material and a sacrificial agent; step S3 is to remove the sacrificial agent, and form a porous lithium storage layer 3 on the inducing layer 2, where the porosity of the current collector 1 is less than 0.1%, and the porosity of the lithium storage layer 3 is greater than the porosity of the current collector 1.
According to the preparation method, the inducing layer 2 is firstly arranged on the surface of the current collector 1, then the lithium storage material precursor is arranged on the inducing layer, and then the sacrificial agent in the lithium storage material precursor is further removed, so that the porous lithium storage layer 3 is formed. The current collector 1 of the negative electrode for the all-solid-state battery has low porosity, so that the compressive capacity of the current collector is high, the requirement of the all-solid-state battery can be met, and the porosity of the lithium storage layer 3 is controlled to be larger than the porosity of the current collector 1 so as to meet the requirement of lithium storage. The formed lithium storage layer is used for storing and depositing lithium, and the inducing layer 2 is used for inducing lithium ions to deposit and store in the lithium storage layer 3, so that the short circuit of the battery caused by disordered growth of lithium dendrites is prevented. In addition, the formed negative electrode structure can isolate deposited lithium from the solid electrolyte layer, and further mechanical damage to the solid electrolyte layer due to volume change caused by deposition and stripping of lithium is avoided. And the structure of the cathode for the all-solid-state battery is simpler, and the cathode is convenient to apply to the all-solid-state battery.
In order to improve the hardness of the current collector 1 and meet the assembly requirement of the all-solid-state battery, the current collector 1 of the present application is made of a denser material, for example, the porosity of the current collector is controlled to be less than 0.1%. In some embodiments, to reduce cost and simplify the structure of the current collector 1, the current collector is a metallic current collector, such as a metallic current collector made of metals including, but not limited to, copper, nickel, and stainless steel.
In some embodiments of the present invention, the inducing material is a metal capable of alloying with lithium ions, and the lithium intercalation potential thereof should be >0.2v (vs li), because lithium ions can preferentially alloy with the material with higher lithium intercalation potential, so that lithium ions are preferentially deposited on the inducing layer 2, and the inducing material used for the inducing layer 2 includes, but is not limited to Ag, In, Zn, Sn, Al, Au, Pt, Mg. In order to increase the energy density of the entire battery, the thickness of the inducing layer 2 should be reduced as much as possible, and the thickness of the inducing layer 2 is preferably 10 to 100nm, more preferably 10 to 30nm, such as 10nm, 20nm, 30nm, 40nm, 45nm, 50nm, 55nm, 60nm, 65nm, 70nm, 80nm, 90nm, and 100 nm. The inducing layer 2 functions to induce lithium metal to be preferentially deposited thereon and then to be deposited in the lithium storage layer 3, thereby inducing deposition of lithium starting from the interface of the inducing layer 2 and the lithium storage layer 3 and growing upward, so that lithium is deposited in the pores of the lithium storage layer 3. The inducing layer 2 only plays a role of inducing lithium metal to be preferentially deposited thereon, and does not serve as a lithium storage space.
In some embodiments, the inducing substance is deposited on the surface of the current collector in step S2 to obtain the inducing layer 2, and the inducing layer 2 formed by the deposition has higher compactness. In some embodiments, for the inducing substance used, it is preferable to deposit the inducing substance on the surface of the current collector 1 by vacuum evaporation or magnetron sputtering. The induction layer 2 is prepared by the method of vacuum evaporation by using the induction substance, so that the induction layer 2 is more uniformly distributed and has a smooth surface, and the uniform distribution of current density is facilitated. The flat surface can generate even expansion in the charging process, thereby preventing the electrolyte layer from cracking caused by uneven local pressure. Vacuum evaporation can prepare thinner induction layer 2, which is beneficial to improving the energy density of the battery. The magnetron sputtering method can be suitable for a wider material range and has the advantages of simple equipment, easy control, large film coating area, high film forming rate, strong adhesive force and the like.
For the same reason as described above, in some embodiments of the present invention, the above step S2 deposits the lithium storage material precursor on the inducing layer 2 to form a denser lithium storage layer precursor. The lithium storage material precursor is preferably deposited on the inducing layer 2 by means of co-sputtering.
After deposition, the sacrificial agent may be removed by utilizing the difference in physical or chemical properties of the sacrificial agent and the electron conductor material, and in some embodiments, to simplify the manner in which the sacrificial agent is removed, the electron conductor material is selected to include carbon and the sacrificial agent is elemental sulfur. Based on the sublimation-prone characteristic of sulfur, it is preferable that the sacrificial agent is removed by heating in step S3 to sublimate and remove sulfur.
The heating temperature should be higher than the sublimation temperature of sulfur in order to completely volatilize sulfur as much as possible, and is preferably 95 to 110 ℃ in view of energy saving.
The deposition and heating method can realize the uniform distribution of the pore canals; meanwhile, the formed pore structure is not easy to collapse and shrink under the external pressure, and is further more suitable for the field of solid batteries. Compared with a method for preparing the three-dimensional pore channel by a coating method, the method does not use a solvent, so that the use and recovery cost of the solvent can be reduced, and the method is more environment-friendly.
In some embodiments of the present invention, the volume ratio of the electron conductor material to the sacrificial agent is 8:2 to 3: 7. The volume ratio of the electron conductor material to the sacrificial agent is within this range, and after removal of the sacrificial agent, the pores of the lithium storage layer are distributed in a more uniform and continuous manner in the framework, providing more ample space for the growth of lithium metal. The co-sputtering of the electron conductor material and the sacrificial agent can be performed by magnetron sputtering, plasma sputtering, vacuum evaporation and other methods commonly used in the art, and the magnetron sputtering, the magnetron sputtering and the vacuum evaporation can all refer to the prior art, for example, when the processes are performed in a vacuum state, for example, when magnetron sputtering is used, the power of an electrode connected with a target is controlled to control the sputtering rate of the substance, and more specifically, when the absolute pressure is 10- 3And on the premise of Pa-0.1 Pa, controlling the power of an electrode connected with the electronic conductor material to be 6-9 kw and the power of an electrode connected with the sacrificial agent to be 1-4 kw, so as to control the volume ratio of the electrode to the sacrificial agent within the range.
The pores of the lithium storage layer 3 provide space for the growth of lithium metal, and the compressive capacity of the lithium storage layer is limited due to the existence of the pores, and in some embodiments of the invention, the porosity of the lithium storage layer 3 is controlled to be 20-70%; or the thickness of the lithium storage layer 3 is controlled to be 5-10 mu m, or the above aspects are cooperatively controlled, so that the lithium storage capacity is improved as much as possible, and the compressive capacity as high as possible is provided. In order to enable lithium ions to be deposited with ready availability of electrons on the framework of the lithium storage layer 3, it is preferred that the conductive framework of the lithium storage layer 3 comprises carbon.
In still another exemplary embodiment of the present application, there is provided an all-solid battery including a positive electrode, a negative electrode, and an electrolyte, the negative electrode including the negative electrode for an all-solid battery of any one of the above or the negative electrode for an all-solid battery prepared by any one of the above-described preparation methods.
The porosity of the current collector of the negative electrode for the all-solid-state battery is small, so that the compressive capacity of the current collector is high, the requirement of the all-solid-state battery can be met, and the porosity of the lithium storage layer is controlled to be larger than the porosity of the current collector so as to meet the requirement of lithium storage. The lithium storage layer for storing and depositing lithium is constructed in the cathode of the all-solid-state battery, and the lithium ions are induced to deposit and store in the lithium storage layer through the inducing layer, so that the battery short circuit caused by disordered growth of lithium dendrites is prevented. In addition, the negative electrode structure can isolate deposited lithium from the solid electrolyte layer, so that mechanical damage to the solid electrolyte layer due to volume change caused by deposition and stripping of lithium is avoided. The structure of the cathode for the all-solid-state battery is simple, the cathode is convenient to apply to the all-solid-state battery, damage of lithium dendrites to a solid electrolyte layer can be effectively avoided, the service life of the all-solid-state battery is effectively prolonged, and the stability and the safety of the all-solid-state battery are guaranteed.
The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.
Example 1
1. Stainless steel foil was used as the current collector.
2. Preparation of the inducing layer:
using metal In as an inducing substance, fixing stainless steel foil on a substrate plate of an evaporation chamber, fixing the metal In on an evaporation source In an evaporation boat until the absolute pressure of the chamber reaches 10-3Below Pa, gradually increasing the evaporation arc current until the evaporation rate stabilizes at
Figure BDA0003228010380000061
And continuously evaporating In on the surface of the current collector at the speed, stopping evaporation when the thickness of the evaporation layer reaches 10nm, cooling to room temperature, and taking out to obtain the current collector with a uniform metal In coating, wherein the metal In coating is an induction layer.
3. Preparing a lithium storage layer:
and sputtering the inducing layer by using vacuum magnetron sputtering equipment to prepare a composite layer of carbon and sulfur.
And (3) placing the current collector with the inducing layer prepared in the step (2) on a rotary sample table, exposing the inducing layer, arranging the assembly positions of a C target and an S target of the magnetron sputtering coating equipment, and taking the elemental carbon and the elemental sulfur as targets to enable the sputtering beam sputtered by the S target and the sputtering beam sputtered by the C target to be sputtered and doped simultaneously to realize overlapping.
Performing vacuum operation on the chamber, and introducing high-purity argon into the chamber until the absolute pressure reaches 0.1 Pa; sputtering, doping and evaporating a C film and an S film in the vacuum environment, enabling S plasma and C plasma to be doped and evaporated on the inducing layer, setting the target power of a C cathode at 6kw, setting the target power of an S cathode at 1.5kw, controlling the volume ratio of C to S in the C-S film to be 8:2, and enabling the deposition thickness of the C-S film layer to be 5 microns, namely the thickness of the lithium storage layer to be 5 microns;
after co-sputtering, the assembly is heated to the sublimation temperature (95 ℃) of sulfur in a vacuum environment to remove the elemental sulfur, so that a conductive framework consisting of carbon and pores left after sulfur removal are left in the negative electrode assembly to form a lithium storage layer, the structure of the lithium storage layer can be calculated according to the difference between the theoretical density and the actual density by referring to fig. 2, and the porosity of the lithium storage layer is 19.7%.
The calculation method is as follows:
the theoretical density is the theoretical density of the material used in the lithium storage layer and can be found;
the actual density calculation method comprises the following steps: rhoPractice of＝mLithium storage layer/VC-S film layer；
Porosity ═ p (p)Theory of the invention-ρPractice of)/ρTheory of the invention。
Example 2
This example 2 is substantially the same as example 1 except that: in step (2), Ag is used as an inducing substance.
Example 3
This example 3 is substantially the same as example 1 except that: in step (2), Zn is used as an inducing substance.
Example 4
This example 4 is substantially the same as example 1 except that: in the step (2), the evaporation time is prolonged to make the thickness of the inducing layer reach 100 nm.
Example 5
This example 5 is substantially the same as example 1 except that: in the step (2), the evaporation time is prolonged to make the thickness of the inducing layer reach 30 nm.
Example 6
This example 6 is substantially the same as example 1 except that: in the step (2), the evaporation time is prolonged to make the thickness of the inducing layer reach 70 nm.
Example 7
This example 7 is substantially the same as example 1 except that: in the step (2), the evaporation time is prolonged to make the thickness of the inducing layer reach 200 nm.
Example 8
This example 8 is substantially the same as example 1 except that: in the step (2), the evaporation time is shortened to make the thickness of the inducing layer reach 2 nm.
Example 9
This example 9 is substantially the same as example 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 5:2, and the porosity is 26.4 percent through calculation of the difference value of the theoretical density and the actual density.
Example 10
This embodiment 10 is substantially the same as embodiment 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 3:7, and the difference between the theoretical density and the actual density is calculated to obtain the porosity of 64.4%.
Example 11
This embodiment 11 is substantially the same as embodiment 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 6:3, and the difference between the theoretical density and the actual density is calculated to obtain the porosity of 31.5%.
Example 12
This example 12 is substantially the same as example 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 5:5, and the difference between the theoretical density and the actual density is calculated to obtain the porosity of 49.7%.
Example 13
This example 13 is substantially the same as example 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 1:7, and the difference between the theoretical density and the actual density is calculated to obtain the porosity of 84.2%.
Example 14
This example 14 is substantially the same as comparative example 1 except that: in the step (3), the component ratio of C to S in the C and S coating films is controlled to be 9:2, and the difference between the theoretical density and the actual density is calculated to obtain the porosity of 16.2%.
Example 15
This example 15 is substantially the same as example 1 except that: in step (3), the magnetron sputtering time was extended to obtain a lithium storage layer with a thickness of 10 μm and the sublimation time was extended until no further sulfur evolution sites were detected, and the calculated porosity was comparable to that of example 1.
Example 16
This example 16 is substantially the same as example 1 except that: in step (3), the magnetron sputtering time was extended to obtain a lithium storage layer with a thickness of 8 μm and the sublimation time was extended until no further sulfur evolution sites were detected, and the calculated porosity was comparable to that of example 1.
Example 17
This example 17 is substantially the same as example 1 except that: in step (3), the magnetron sputtering time was extended to obtain a lithium storage layer having a thickness of 20 μm, and the sublimation time was extended until no further sulfur evolution sites were detected, and the porosity was calculated to be slightly smaller than that of example 1.
Example 18
This example 18 is substantially the same as example 1 except that: in step (3), the magnetron sputtering time was shortened to obtain a lithium storage layer with a thickness of 2 μm and the sublimation time was shortened until no further sulfur evolution sites were detected, the calculated porosity being comparable to example 1.
Comparative example 1
1. Stainless steel foil was used as the current collector.
2. Preparing a lithium storage layer:
and sputtering on one surface of a current collector of a vacuum magnetron sputtering device to prepare a carbon and sulfur composite layer.
And placing the current collector on a rotary sample table, and arranging the mounting positions of a C target and an S target of magnetron sputtering coating equipment to realize the overlapping of sputtering beams sputtered by the S target and sputtering doping sputtered by the C target.
Performing vacuum operation on the chamber, and introducing high-purity argon into the chamber until the absolute pressure reaches 0.1 Pa; sputtering, doping and evaporating a C film and an S film in the vacuum environment, enabling S plasma and C plasma to be doped and evaporated on the inducing layer, setting the target power of a C cathode at 6kw and the target power of an S cathode at 1.5kw, repeating experimental adjustment, controlling the component ratio of C to S in the C film and the S film to be 8:2, and enabling the C-S film layer to be 5 microns in deposition thickness;
after co-sputtering, the assembly was heated in a vacuum environment to the sublimation temperature (95 ℃) of sulfur to remove elemental sulfur, leaving an electron conductor skeleton consisting of carbon and pores in the negative electrode assembly left after sulfur removal, wherein the porosity was 16.8%.
The cell was subjected to a charge-discharge cycle test at a rate of 0.1C. The time-voltage diagram is shown in fig. 5.
Comparative example 2
A stainless steel current collector was used as the negative electrode, i.e. no treatment was done on the negative electrode side.
Assembling the battery:
a solid electrolyte layer was prepared using sulfide lipsccl as a solid electrolyte. The ratio of lipsccl to binder PVDF in the electrolyte layer was 95: 5.
The positive electrode plate used in the solid-state battery is as follows: the positive electrode active material is NCM811, the solid electrolyte is LPSCl, the binder is PVDF, and the conductive carbon is SP. The ratio of NCM811 to LPSCl to PVDF to SP was 60:30:5:5, and aluminum foil was used as the positive electrode current collector.
Each example or comparative example was assembled into an all-solid battery in the order of a positive electrode, a solid electrolyte, and a negative electrode.
The all-solid-state batteries according to the examples were subjected to charge-discharge cycle tests at a rate of 0.1C. Wherein, the time-voltage diagram of the all-solid battery of example 1 is shown in fig. 3; the time-voltage diagram of the all-solid battery of comparative example 1 is shown in fig. 4; the time-voltage diagram of the all-solid battery of comparative example 2 is shown in fig. 5;
as can be seen from fig. 4, the first cycle efficiency of the battery prepared using the negative electrode in comparative example 1 was 81%; this first effect is significantly reduced from that of the battery of example 1, because lithium dendrite growth causes contact between lithium metal and the sulfide electrolyte, which causes decomposition of the sulfide electrolyte. And short circuits due to lithium dendrite growth occurred after 150h of the cycle. As can be seen from fig. 5, the battery prepared from the negative electrode in comparative example 2 suffered from a short circuit phenomenon during the first-cycle charging, which was caused by penetration of the electrolyte layer by the growth of lithium dendrites.
TABLE 1
Figure BDA0003228010380000101
Figure BDA0003228010380000111
According to the data, the cycle life of the cathode for the all-solid-state battery is effectively prolonged, and the first effect is basically maintained to be more than 80%.
From the above description, it can be seen that the above-described embodiments of the present invention achieve the following technical effects:
the porosity of the current collector of the negative electrode for the all-solid-state battery is small, so that the compressive capacity of the current collector is high, the requirement of the all-solid-state battery can be met, and the porosity of the lithium storage layer is controlled to be larger than the porosity of the current collector so as to meet the requirement of lithium storage. The lithium storage layer for storing and depositing lithium is constructed in the cathode of the all-solid-state battery, and the lithium ions are induced to deposit and store in the lithium storage layer through the inducing layer, so that the battery short circuit caused by disordered growth of lithium dendrites is prevented. In addition, the negative electrode structure can isolate deposited lithium from the solid electrolyte layer, so that mechanical damage to the solid electrolyte layer due to volume change caused by deposition and stripping of lithium is avoided. The structure of the cathode for the all-solid-state battery is simple, the cathode is convenient to apply to the all-solid-state battery, damage of lithium dendrites to a solid electrolyte layer can be effectively avoided, the service life of the all-solid-state battery is effectively prolonged, and the stability and the safety of the all-solid-state battery are guaranteed.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. An anode for an all-solid battery, characterized by comprising: from the bottom up sets gradually the mass flow body, induced layer, lithium storage layer, the porosity of the mass flow body is less than 0.1%, lithium storage layer is porous conducting layer, the porosity of porous conducting layer is greater than the porosity of the mass flow body.
2. The negative electrode for all-solid batteries according to claim 1, wherein the current collector is a metallic current collector, preferably the metal of the metallic current collector is selected from one of copper, nickel, and stainless steel.
3. The negative electrode for all-solid batteries according to claim 1, wherein the inducing substance used In the inducing layer is one or more selected from Ag, In, Zn, Sn, Al, Au, Pt, and Mg;
preferably, the thickness of the inducing layer is 10-100 nm.
4. The negative electrode for all-solid batteries according to claim 1, wherein the porosity of the lithium storage layer is 20 to 70%,
preferably, the conductive framework of the lithium storage layer comprises carbon;
further preferably, the thickness of the lithium storage layer is 5 to 10 μm.
5. A preparation method of a negative electrode for an all-solid battery is characterized by comprising the following steps:
step S1, arranging an inducing substance on the surface of the current collector to obtain an inducing layer;
step S2 of disposing a lithium storage material precursor on the inducing layer, the lithium storage material precursor including an electron conductor material and a sacrificial agent;
step S3, removing the sacrificial agent, and forming a porous lithium storage layer on the inducing layer, wherein the porosity of the current collector is less than 0.1%, and the porosity of the lithium storage layer is greater than the porosity of the current collector.
6. The method according to claim 5, wherein the current collector is a metallic current collector, and preferably the metal of the metallic current collector is selected from one of copper, nickel and stainless steel.
7. The method according to claim 5, wherein the inducing substance is selected from one or more of Ag, In, Zn, Sn, Al, Au, Pt, and Mg;
preferably, the thickness of the inducing layer is 10-100 nm;
preferably, in step S2, an inducing substance is deposited on the surface of the current collector to obtain the inducing layer, and further preferably, the inducing substance is deposited on the surface of the current collector by using a vacuum evaporation or magnetron sputtering method.
8. The production method according to claim 5, wherein the step S2 deposits the lithium storage material precursor on the inducing layer, preferably by co-sputtering; the electronic conductor material comprises carbon, the sacrificial agent is elemental sulfur, the sacrificial agent is preferably removed in a heating mode in the step S3, the heating temperature is preferably 95-110 ℃, and the volume ratio of the electronic conductor material to the sacrificial agent is preferably 8: 2-3: 7.
9. The method according to claim 5, wherein the lithium storage layer has a thickness of 5 to 10 μm.
10. An all-solid battery comprising a positive electrode, a negative electrode and an electrolyte, wherein the negative electrode comprises the negative electrode for the all-solid battery according to any one of claims 1 to 4 or the negative electrode for the all-solid battery prepared by the preparation method according to any one of claims 5 to 9.
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