CN115360327A - Composite lithium metal negative electrode and preparation method and application thereof - Google Patents

Composite lithium metal negative electrode and preparation method and application thereof Download PDF

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CN115360327A
CN115360327A CN202210823461.3A CN202210823461A CN115360327A CN 115360327 A CN115360327 A CN 115360327A CN 202210823461 A CN202210823461 A CN 202210823461A CN 115360327 A CN115360327 A CN 115360327A
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lithium metal
negative electrode
composite
electrode
lithium
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徐林
张楠楠
麦立强
王学文
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Foshan Xianhu Laboratory
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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
    • 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
    • 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
    • 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
    • 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

The invention belongs to the technical field of lithium metal batteries, and particularly relates to a composite lithium metal negative electrode and a preparation method and application thereof. The preparation method of the composite lithium metal negative electrode comprises the following steps: carrying out electrochemical deposition on a matrix material, and drying in vacuum to obtain a composite metal simple substance matrix; soaking the composite metal simple substance matrix in a graphene oxide solution, and drying to obtain an electrode material; and pre-depositing lithium on the electrode material to obtain the lithium-ion battery. The composite lithium metal negative electrode of the present invention has a lithium metal restrictive deposition/dissolution cavity and lithium-philic X-O-C chemical bonds, wherein the chemical bonds formed ensure structural stability while providing lithium-philic deposition sites to guide uniform deposition of lithium metal within the cavity to inhibit dendritic growth. The lithium metal battery cathode material is used as a negative electrode of the lithium metal battery, and the cycle performance of the lithium metal battery is greatly improved.

Description

Composite lithium metal negative electrode and preparation method and application thereof
Technical Field
The invention belongs to the technical field of lithium metal batteries, and particularly relates to a composite lithium metal negative electrode and a preparation method and application thereof.
Background
Today, the demand for energy density of batteries is increasing due to the development of electric automobiles, portable electronic products, aerospace and large-scale electricity storage facilities, and the conventional commercial lithium ion batteries are limited by the lower theoretical capacity (372 mAh g) of graphite cathodes -1 ) Higher energy densities have not been achieved. Therefore, the search for new electrode materials to replace graphite electrode materials is an urgent need in recent years. The novel electrode material needs to satisfy the following points: (1) has ultra-high specific capacity; (2) excellent conductivity; (3) stable physicochemical properties and structure; and (4) the method is safe, reliable and low in cost.
Metallic lithium, as an element of the first main group of the periodic Table of the elements, not only has a high theoretical capacity (3860 mAh g) -1 Ten times that of graphite cathode) and has a low electrochemical potential (-3.04V relative to hydrogen standard electrode potential), can match most cathode materials, and is considered as a promising next-generation battery cathode material. However, when the lithium metal is used as a negative electrode, the instability of an electrode/electrolyte solution interface can cause uneven lithium deposition in the process of charging and discharging, and dendritic lithium dendrites are further formed, so that a serious safety hazard is brought.
Therefore, several key technical problems need to be solved before lithium metal negative electrodes are put to practical use. (1) interfacial side reactions. Metallic lithium has a high chemical and electrochemical reactivity, which means that lithium metal continuously reacts with almost all liquid electrolytes at the interface, resulting in corrosion and reduced utilization of the lithium metal negative electrode, and a thin Solid Electrolyte Interface (SEI) layer is formed on the surface of the electrode. However, the compactness and mechanical strength of the SEI layer are not sufficient to inhibit further reactions at the electrode/electrolyte interface, leading to further aggravation of interfacial side reactions, and the SEI layer is continuously restructured, thereby reducing the coulombic efficiency and the cycle stability of the lithium metal negative electrode. (2) lithium dendrites. In the lithium ion deposition process, the non-uniform electric field distribution on the surface of the electrode causes non-uniform lithium ion current distribution, causes non-uniform lithium deposition and finally generates lithium dendrite. Dendritic lithium dendrites have the potential to penetrate the separator, causing a number of safety issues such as: internal short circuits, thermal runaway, etc. In addition, lithium dendrites are easily broken off from the root, forming "dead lithium". And (3) volume effect. Metallic lithium acts as a "bulk-free" negative electrode, similar to silicon negative electrodes, and the electrode expands and contracts during deposition/stripping of lithium, thereby affecting the coulombic efficiency and cycling stability of the battery. This is a big contradiction and challenge between the intrinsic properties of lithium metal and the requirements for application as a negative electrode material of a secondary battery.
Therefore, in order to realize the industrial application of the lithium metal negative electrode, it is necessary to overcome the above-mentioned technical problems, and to improve the electrochemical performance and simultaneously ensure the structural stability.
Disclosure of Invention
The invention provides a composite lithium metal cathode, a preparation method and an application thereof, which aim to solve one or more technical problems in the prior art and at least provide a beneficial selection or creation condition.
In order to overcome the technical problems, the invention provides a preparation method of a composite lithium metal negative electrode in a first aspect.
Specifically, the preparation method of the composite lithium metal negative electrode comprises the following steps:
(1) Carrying out electrochemical deposition on a matrix material, and drying in vacuum to obtain a composite metal simple substance matrix; the metal simple substance is zinc or nickel;
(2) Soaking the composite metal simple substance matrix in a graphene oxide solution, and drying to obtain an electrode material;
(3) And pre-depositing lithium on the electrode material to obtain the composite lithium metal negative electrode.
Firstly, electroplating metal simple substance zinc or nickel on a substrate material in an electrochemical deposition mode to prepare a composite metal simple substance substrate; then soaking the substrate of the composite metal simple substance in a graphene oxide solution, carrying out oxidation-reduction reaction on the graphene oxide and the metal simple substance, and obtaining an electrode material of a composite interface layer with a tent-shaped cavity through self-assembly; and finally, assembling a half cell to pre-deposit the metal lithium on an electrode material to obtain the composite lithium metal cathode. The composite lithium metal negative electrode has a lithium metal restricted deposition/dissolution cavity and lithium-philic X-O-C chemical bonds (X = Zn or Ni), wherein the chemical bonds formed ensure structural stability while providing lithium-philic deposition sites to guide uniform deposition of lithium metal within the cavity to inhibit dendritic growth. The prepared composite lithium metal negative electrode is used as the negative electrode of the lithium metal battery, and the cycle performance of the lithium metal battery is greatly improved.
As a further improvement of the above, the electrolyte solution used for the electrochemical deposition includes boric acid, a transition metal salt, and a sodium salt;
the transition metal salt comprises any one of zinc sulfate, nickel sulfate, zinc chloride and nickel chloride;
the sodium salt includes sodium sulfate or sodium chloride.
Specifically, the transition metal salt provides metal ions for the electrolyte solution, and the metal ions are deposited on the base material in the form of metal simple substances in the electrochemical deposition process; boric acid and sodium salts provide charge carriers for the electrochemical deposition process.
As a further improvement of the above aspect, the mass ratio of the boric acid, the transition metal salt and the sodium salt is (0.1-0.2): 1:1.
as a further improvement of the above scheme, the concentration of the graphene oxide solution is 0.04-0.4g/L; the pH value of the graphene oxide solution is 4-6.
Preferably, the graphene oxide solution is synthesized by a hummer method.
Preferably, the pH of the graphene oxide solution is 5.
Specifically, a weakly acidic solution is selected, which is more favorable for ensuring that the graphene oxide and the metal simple substance in the electrochemical deposition product are subjected to oxidation-reduction reaction, so that the self-assembly of the graphite oxide is realized.
Preferably, the matrix material comprises any one of carbon cloth, copper foam and nickel foam.
As a further improvement of the above aspect, the base material further comprises a step of pretreatment before performing electrochemical deposition; the pretreatment process comprises the following steps: under the ultrasonic condition, hydrochloric acid, acetone, deionized water and ethanol are sequentially adopted for soaking, and then drying is carried out. The base material is pretreated, and the method is mainly used for removing impurities on the surface of the base material.
As a further improvement of the above scheme, the process of the electrochemical deposition comprises: using 0.04-0.06mA cm -2 The constant current deposition is carried out for 10-600 seconds, wherein AgCl is used as a reference electrode, and a Pt electrode is used as a counter electrode.
Preferably, the time of the electrochemical deposition is 5 to 10 minutes.
Preferably, the temperature of the vacuum drying is 50-80 ℃.
As a further improvement of the above scheme, the process of pre-depositing lithium on the electrode material comprises: the electrode material is used as a positive electrode, a lithium sheet is used as a negative electrode to assemble a half cell, and the discharge capacity is 3-5mAh cm -2 And carrying out primary discharge to obtain the electrode with pre-deposited lithium.
A second aspect of the invention provides a composite lithium metal anode.
Specifically, the composite lithium metal negative electrode is prepared by the preparation method of the composite lithium metal negative electrode.
The composite lithium metal cathode disclosed by the invention utilizes graphene oxide to carry out self-assembly on metal simple substance zinc or nickel so as to construct an artificial interface layer of a tent-shaped cavity, and a chemical bond X-O-C formed by a charge transmission effect generated in the self-assembly process has strong affinity with metal lithium.
A third aspect of the invention provides the use of a composite lithium metal anode.
Specifically, the lithium metal battery comprises a positive electrode, an electrolyte solution, a diaphragm and a negative electrode, wherein the negative electrode is the composite lithium metal negative electrode.
Compared with the prior art, the technical scheme of the invention at least has the following technical effects or advantages:
(1) According to the invention, elemental zinc or nickel is electroplated on a base material in an electrochemical deposition mode, and then the base material is soaked in a graphene oxide solution, so that the graphene oxide and the elemental metal undergo redox reaction to form a lithium-philic chemical bond X-O-C, the stability of the structure is ensured while lithium-philic deposition sites are provided, the growth of lithium dendrites can be effectively inhibited through self-assembling preset limiting deposition cavities, the construction of an SEI layer is beneficial to the transmission of interface ions, and the chemical impedance value is low and stable.
(2) The symmetrical battery assembled by the composite lithium metal cathode can realize 1600h of circulation, and the polarization voltage can be as low as 11mV; the capacity retention rate of the assembled full battery can reach 94.5% after the performance of the assembled full battery is 3000 circles under 5C.
(3) The preparation method of the composite lithium metal cathode is simple, has low cost and is beneficial to large-scale industrial production.
Drawings
FIG. 1 is a scanning electron micrograph of samples a and b prepared in example 1;
FIG. 2 is a high resolution TEM image of sample b prepared in example 1;
FIG. 3 is a representation of the X-O-C bond of sample b prepared in example 1;
FIG. 4 is a graph comparing the performance of Electrochemical Impedance Spectroscopy (EIS) of samples B and A obtained in example 1 and comparative example 1;
FIG. 5 shows pre-deposited lithium 5mAh cm for samples a and b prepared in example 1 -2 Comparing the images by a scanning electron microscope;
FIG. 6 is a graph comparing the cycling performance of symmetrical cells for samples B and A obtained in example 1 and comparative example 1;
FIG. 7 is a graph comparing full cell Li | | | LFP performance of samples B and A made in example 1 and comparative example 1;
fig. 8 is a graph comparing the rate performance of full-cell Li | | | LFP of samples B and a prepared in example 1 and comparative example 1.
Detailed Description
The present invention is specifically described below with reference to examples in order to facilitate understanding of the present invention by those skilled in the art. It is to be expressly understood that the examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention, as those skilled in the art will appreciate that various modifications and adaptations of the present invention as set forth herein are possible and can be made without departing from the spirit and scope of the present invention. Meanwhile, the raw materials mentioned below are not specified in detail and are all commercial products; the process steps or preparation methods not mentioned in detail are all process steps or preparation methods known to the person skilled in the art.
Example 1
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of zinc sulfate heptahydrate and 25g of anhydrous sodium sulfate, dissolving the mixture in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a;
(4) Putting the sample a prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 5min, and repeating for 5 times to obtain a sample b;
(5) Pre-depositing 3mAh cm of lithium on the sample b prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B.
Example 2
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of zinc chloride and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.05mA cm -2 For the constant current of (2)Performing electrochemical deposition on the carbon cloth for 10min; then washing with deionized water, and drying in a drying oven at 80 ℃ to obtain a sample a-2;
(4) Placing the sample a-2 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 5min, and repeating for 1 time to obtain a sample b-2;
(5) Pre-depositing 3mAh cm of lithium on the sample b-2 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-2.
Example 3
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of zinc sulfate heptahydrate and 25g of sodium chloride, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.06mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 60 ℃ to obtain a sample a-3;
(4) Putting the sample a-3 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 5min, and repeating for 5 times to obtain a sample b-3;
(5) Pre-depositing 3mAh cm of lithium on the sample b-3 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-3.
Example 4
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 2.5g of boric acid, 25g of nickel chloride and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode, pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 5min by using the constant current; then washing with deionized water, and drying in a drying oven at 80 ℃ to obtain a sample a-4;
(4) Placing the sample a-4 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to 5, soaking for 1min, taking out, drying for 5min, and repeating for 1 time to obtain a sample b-4;
(5) Pre-depositing 3mAh cm of lithium on the sample b-4 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-4.
Example 5
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of zinc sulfate heptahydrate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 5min by using the constant current; then washing with deionized water, and drying in a drying oven at 60 ℃ to obtain a sample a-5;
(4) Putting the sample a-5 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to 5, soaking for 1min, taking out, drying for 5min, and repeating for 1 time to obtain a sample b-5;
(5) Pre-depositing 3mAh cm of lithium on the sample b-5 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-5.
Example 6
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 5g of boric acid, 25g of zinc sulfate heptahydrate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a-6;
(4) Placing the sample a-6 prepared in the step (3) in a graphene oxide aqueous solution with the concentration of 0.4g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 3min, and repeating for 8 times to obtain a sample b-6;
(5) Pre-depositing 3mAh cm of lithium on the sample b-6 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-6.
Example 7
A method for preparing a composite lithium metal negative electrode, comprising the steps of:
(1) Weighing 4g of boric acid, 25g of zinc sulfate heptahydrate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a-7;
(4) Placing the sample a-7 prepared in the step (3) in a graphene oxide aqueous solution with the concentration of 0.4g/L, adjusting the pH value of the solution to be 5, soaking for 10min, taking out, drying for 1min, and repeating for 8 times to obtain a sample b-7;
(5) Pre-depositing 3mAh cm of lithium on the sample b-7 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-7.
Example 8
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of nickel sulfate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode, and Pt as a counter electrode, and adopting 0.4mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a-8;
(4) Putting the sample a-8 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.4g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 5min, and repeating for 5 times to obtain a sample b-8;
(5) Pre-depositing 3mAh cm of lithium on the sample b-8 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-8.
Example 9
A preparation method of a composite lithium metal negative electrode comprises the following steps:
(1) Weighing 4g of boric acid, 25g of nickel sulfate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode, and Pt as a counter electrode, and adopting 0.4mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a-9;
(4) Putting the sample a-9 prepared in the step (3) into a graphene oxide aqueous solution with the concentration of 0.04g/L, adjusting the pH value of the solution to be 5, soaking for 10min, taking out, drying for 1min, and repeating for 5 times to obtain a sample b-9;
(5) Will be provided withSample b-9 prepared in step (4) is pre-deposited with lithium of 3mAh cm -2 And obtaining a composite lithium metal negative electrode sample B-9.
Example 10
A method for preparing a composite lithium metal negative electrode, comprising the steps of:
(1) Weighing 4g of boric acid, 25g of nickel sulfate and 25g of anhydrous sodium sulfate, dissolving the boric acid, the nickel sulfate and the anhydrous sodium sulfate in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode, pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 8min by using the constant current; then washing with deionized water, and drying in a drying oven at 60 ℃ to obtain a sample a-10;
(4) Placing the sample a-10 prepared in the step (3) in a graphene oxide aqueous solution with the concentration of 0.4g/L, adjusting the pH value of the solution to be 5, soaking for 1min, taking out, drying for 5min, and repeating for 5 times to obtain a sample b-10;
(5) Pre-depositing 5mAh cm of lithium on the sample b-10 prepared in the step (4) -2 And obtaining a composite lithium metal negative electrode sample B-10.
Comparative example 1
A method for preparing a composite lithium metal negative electrode, comprising the steps of:
(1) Weighing 4g of boric acid, 25g of zinc sulfate heptahydrate and 25g of anhydrous sodium sulfate, dissolving in 200ml of deionized water, and stirring to obtain a clear solution;
(2) Under the ultrasonic condition, sequentially adopting hydrochloric acid, acetone, deionized water and ethanol to soak the carbon cloth, and drying the carbon cloth for later use;
(3) Taking the solution prepared in the step (1) as an electrolyte solution, agCl as a reference electrode and Pt as a counter electrode, and adopting 0.04mA cm -2 Performing electrochemical deposition on the carbon cloth treated in the step (2) for 10min by using the constant current; then washing with deionized water, and drying in a drying oven at 50 ℃ to obtain a sample a;
(4) Pre-treating the sample a prepared in the step (3)Deposit lithium 3mAh cm -2 And obtaining a composite lithium metal negative electrode sample A.
Comparative example 1 differs from example 1 only in that: sample a, prepared in comparative example 1, was not placed in an aqueous graphene oxide solution, but was directly subjected to lithium pre-deposition.
Performance testing
1. Microstructure analysis
FIG. 1 is a scanning electron micrograph of samples a and b prepared in example 1, wherein FIGS. 1-a and 1-b are microstructures of sample a and sample b, respectively; FIG. 2 is a high resolution TEM image of sample b prepared in example 1; FIG. 5 shows pre-deposited lithium 5mAh cm for samples a and b prepared in example 1 -2 Scanning electron microscope comparison graph.
As can be seen from fig. 1, after the graphene oxide is self-assembled, the appearance of the sample is also greatly changed due to the interfacial reaction on the surface. As can be seen from fig. 2, a tent-like hollow nano-cavity exists in sample b, and GO in the figure represents graphene oxide. As can be seen from fig. 5, sample b is more favorable for uniform deposition of lithium.
2. Characterization of chemical bonds
FIG. 3 is a representation of the X-O-C bond of sample b obtained in example 1, wherein FIGS. 3-a, 3-b, 3-C represent the spectra of C1s, O1 s, zn 2p, respectively, whereby the presence of the Zn-O-C bond can be demonstrated.
3. Electrochemical impedance performance
Fig. 4 is a graph comparing the performance of Electrochemical Impedance Spectroscopy (EIS) before and after cycling of samples B and a prepared in example 1 and comparative example 1, and it can be seen from fig. 4 that the interfacial contact of sample B is significantly better than that of sample a.
4. Battery application testing
Samples a and B prepared in comparative example 1 and example 1 were assembled into a symmetrical electronic scale and a full cell (matched LFP positive electrode), respectively, for testing the cycling stability and reversibility of the cells.
Fig. 6 to 8 are a comparative graph of the cycle performance of the symmetrical batteries, a comparative graph of the full-battery Li | | LFP performance, and a comparative graph of the rate performance of Li | | | LFP of the samples B and a obtained in example 1 and comparative example 1, respectively. As can be seen from FIGS. 6-8: sample B was more favorable to stabilize long cycles.
The samples produced in inventive examples 2-10 all had similar structure and properties to those of example 1.
It will be obvious to those skilled in the art that many simple derivations or substitutions can be made without inventive effort without departing from the inventive concept. Therefore, simple modifications to the present invention by those skilled in the art according to the present disclosure should be within the scope of the present invention. The above embodiments are preferred embodiments of the present invention, and all similar processes and equivalent variations to those of the present invention should fall within the scope of the present invention.

Claims (10)

1. The preparation method of the composite lithium metal negative electrode is characterized by comprising the following steps of:
(1) Carrying out electrochemical deposition on the matrix material, and drying in vacuum to obtain a composite metal simple substance matrix; the metal simple substance is zinc or nickel;
(2) Soaking the composite metal simple substance matrix in a graphene oxide solution, and drying to obtain an electrode material;
(3) And pre-depositing lithium on the electrode material to obtain the composite lithium metal negative electrode.
2. The method of preparing a composite lithium metal anode according to claim 1, wherein the electrolyte solution used for the electrochemical deposition comprises boric acid, a transition metal salt and a sodium salt;
the transition metal salt comprises any one of zinc sulfate, nickel sulfate, zinc chloride and nickel chloride;
the sodium salt includes sodium sulfate or sodium chloride.
3. The method of producing a composite lithium metal anode according to claim 2, characterized in that the mass ratio of the boric acid, the transition metal salt and the sodium salt is (0.1-0.2): 1:1.
4. the method of preparing the composite lithium metal anode according to claim 1, wherein the concentration of the graphene oxide solution is 0.04 to 0.4g/L; the pH value of the graphene oxide solution is 4-6.
5. The method of preparing a composite lithium metal anode according to claim 1, wherein the matrix material comprises any one of carbon cloth, copper foam, and nickel foam.
6. The method of preparing a composite lithium metal anode of claim 1, wherein the matrix material further comprises a step of pretreatment before electrochemical deposition;
the pretreatment process comprises the following steps: under the ultrasonic condition, hydrochloric acid, acetone, deionized water and ethanol are sequentially adopted for soaking, and then drying is carried out.
7. The method for preparing the composite lithium metal negative electrode according to claim 1, wherein the electrochemical deposition comprises the following steps: using 0.04-0.06mA cm -2 The constant current deposition is carried out for 10-600 seconds, wherein AgCl is used as a reference electrode, and a Pt electrode is used as a counter electrode; the time of the electrochemical deposition is 5-10 minutes.
8. The method for preparing the composite lithium metal negative electrode according to claim 1, wherein the process for pre-depositing lithium on the electrode material comprises the following steps: the electrode material is used as a positive electrode, a lithium sheet is used as a negative electrode to assemble a half cell, and the discharge capacity is 3-5mAh cm -2 And carrying out primary discharge to obtain the electrode with pre-deposited lithium.
9. A composite lithium metal negative electrode, characterized by being produced by the method for producing a composite lithium metal negative electrode according to any one of claims 1 to 8.
10. A lithium metal battery comprising a positive electrode, an electrolyte solution, a separator, and a negative electrode, wherein the negative electrode is the composite lithium metal negative electrode according to claim 9.
CN202210823461.3A 2022-07-13 2022-07-13 Composite lithium metal negative electrode and preparation method and application thereof Pending CN115360327A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115986059A (en) * 2023-01-17 2023-04-18 武汉理工大学 Graphene oxide assisted seed crystal stabilized composite cathode and preparation method and application thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN115986059A (en) * 2023-01-17 2023-04-18 武汉理工大学 Graphene oxide assisted seed crystal stabilized composite cathode and preparation method and application thereof

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