A modified three-dimensional copper framework lithium metal composite lithium battery negative electrode material and a preparation method thereof

Abstract

The application belongs to the technical field of lithium ion battery materials, and discloses a modified three-dimensional copper framework lithium battery negative electrode material combined with lithium metal and a preparation method thereof.The preparation method specifically comprises the following steps: (1) placing a copper mesh in a solution of citric acid and a lithium salt, heating and evaporating to dryness, and calcining under a protective atmosphere to obtain a pretreated current collector; (2) mixing the pretreated current collector with sulfur, selenium and a reducing agent in an organic solvent to perform a solvothermal reaction; and (3) immersing the electrode sheet after the solvothermal reaction in molten lithium metal in an argon glove box, and cooling, to obtain the modified three-dimensional copper framework lithium battery negative electrode material combined with lithium metal.The material prepared by the application has high structural stability, and the process is simple and easy to operate.The pretreatment of the copper mesh current collector increases the flatness of the deposited lithium, and improves the structural stability and electrochemical performance of the material.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery manufacturing technology, specifically relating to a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal and its preparation method. Background Technology

[0002] Since its invention, lithium-ion batteries have been favored for commercial production due to their high energy density and long cycle stability, and are now widely used in transportation, portable energy storage devices, and other fields. However, as the energy density requirements for lithium-ion batteries increase, the theoretical specific capacity of traditional graphite anodes limits their application in high-capacity lithium-ion batteries. Therefore, developing lithium-ion battery anode materials with high specific capacity and low reaction potential is extremely important.

[0003] Lithium metal is currently the anode material for lithium-ion batteries with extremely high theoretical specific capacity. Unlike other anode materials, lithium metal itself does not require other materials as a framework, and its low molar mass results in higher gravimetric and volumetric energy density compared to other materials. Historically, lithium metal anode materials have been used in batteries for a long time, but their application in rechargeable batteries has been limited. This is because lithium metal deposition is highly prone to the formation of lithium dendrites. The breakage of excessively large lithium dendrites can lead to excessive side reactions between lithium and the electrolyte. Furthermore, lithium dendrites are also highly likely to puncture the separator, causing short circuits. Therefore, the modification of lithium metal is extremely important.

[0004] To address the above issues, we utilize a three-dimensional copper framework as the substrate for the anode material. We modify the three-dimensional copper framework using carbon coating, pre-lithiation, and in-situ selenization-sulfidation to increase the material's conductivity and lithiophilicity, facilitating subsequent adsorption of liquid lithium metal. Finally, the modified three-dimensional copper framework adsorbs molten lithium to obtain the anode material. This material exhibits high conductivity, strong lithium-ion adsorption, and high energy density. The modified copper framework significantly smooths the lithium-ion deposition reaction. The composite lithium metal-modified three-dimensional copper framework lithium-ion battery anode material of this invention greatly contributes to improving the performance of lithium-ion batteries. Summary of the Invention

[0005] This invention provides a modified three-dimensional copper framework lithium-ion battery anode material with composite lithium metal and its preparation method. The invention utilizes a solution method and high-temperature calcination to form an in-situ carbon coating and lithium element modification layer on the outside of a three-dimensional carbon framework, followed by hydrothermal sulfidation and selenization. Finally, molten lithium is adsorbed to obtain the modified three-dimensional copper framework lithium-ion battery anode material with modified lithium metal, improving the material's stability and surface smoothness, and increasing its stability during cycling.

[0006] The objective of this invention is specifically achieved through the following solution:

[0007] A method for preparing a modified three-dimensional copper framework lithium-ion battery anode material with composite lithium metal, comprising the following steps:

[0008] (1) The three-dimensional copper mesh is placed in an aqueous solution of citric acid and lithium salt in a certain proportion, heated and dried in a forced-air oven, and sintered under a reducing atmosphere to obtain a pretreated current collector.

[0009] (2) The pretreated current collector prepared in (1) and a certain proportion of sulfur source and selenium source are added to an organic solvent, and then a reducing agent is added. After thorough mixing, the dispersion is placed in a polytetrafluoroethylene reactor for solvothermal reaction.

[0010] (3) After the solvothermal reaction is completed, the copper mesh is washed and dried, and then heated to melt metallic lithium in an argon atmosphere glove box. The copper mesh is then soaked in liquid metallic lithium and taken out to cool, thus obtaining the modified three-dimensional copper skeleton lithium battery anode material of composite lithium metal.

[0011] Preferably, the copper mesh described in step (1) is a circular sheet with a diameter of 12.0 mm and a thickness of 1.0 mm, wherein the copper wire has a diameter of 10-20 micrometers;

[0012] Preferably, the lithium salt mentioned in step (1) is lithium chloride, lithium nitrate or lithium oxalate;

[0013] Preferably, the ratio of citric acid to lithium salt in step (1) is 100:(5-1) (mass ratio);

[0014] Preferably, the heating and drying conditions of the blower oven in step (1) are 100-120 degrees Celsius for 6 hours;

[0015] Preferably, the reducing atmosphere in step (1) is H2+Ar (10%), the sintering temperature is 700-900 degrees Celsius, and the sintering time is 2-6 hours;

[0016] Preferably, the sulfur source in step (2) is sodium sulfide, thioacetamide or thiourea, the selenium source is selenium dioxide, and the organic solvent is ethanol, ethylene glycol or glycerol;

[0017] Preferably, the ratio of sulfur source to selenium source in step (2) is 1:(0.9-1.1);

[0018] Preferably, the temperature of the solvothermal reaction in step (2) is 150-200 degrees Celsius, and the reaction time is 8-24 hours;

[0019] Preferably, the reducing agent in step (2) is hydrazine hydrate or sodium borohydride;

[0020] Preferably, the heating of molten lithium metal in step (3) is carried out at a heating temperature of 200-300 degrees Celsius, at a cooling temperature of room temperature, and for a cooling time of 5-10 minutes.

[0021] This invention significantly enhances the lithium affinity of copper materials through carbon coating and pre-lithiation treatment of copper mesh, followed by in-situ sulfidation and selenization of copper. This process smooths the deposition surface during lithium deposition, reduces lithium dendrite formation, and increases material stability. This approach greatly improves the cycle performance and extends the lifespan of the material. This invention presents a low-cost and easily implemented modification method that can significantly improve the electrochemical performance of lithium-ion battery lithium metal anodes, demonstrating promising application prospects. Attached Figure Description

[0022] Figure 1 This is a SEM image of the product in Example 1 of the present invention. Figure 2 The diagram shows the cyclic performance of Example 1, Example 2, and Comparative Example 1. Detailed Implementation

[0023] Example 1

[0024] (1) Take 0.5 g of citric acid, 0.01 g of lithium chloride and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix it thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0025] (2) Take 0.5 g of thioacetamide, 0.53 g of selenium powder, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 180 degrees Celsius for 12 hours.

[0026] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0027] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0028] The morphology of the material Figure 1 The battery was showcased in the exhibition. After 12 hours of aging following assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 500 cycles at a current density of 5.0C and a voltage range of 0.01-3V, exhibited a discharge specific capacity of 602.5 mA hg. -1 The capacity retention rate was 79.86%.

[0029] Comparative Example 1

[0030] (1) Take 0.5 g of citric acid, 0.01 g of lithium chloride and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix it thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0031] (2) Take 0.5 g of thioacetamide, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 180 degrees Celsius for 12 hours.

[0032] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0033] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0034] The morphology of the material Figure 1 The battery was showcased in the exhibition. After 12 hours of aging following assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 221 cycles at a voltage of 0.01-3V and a current density of 5.0C, exhibited a discharge specific capacity of 136.90 mA hg. -1 The capacity retention rate was 27.02%.

[0035] Comparative Example 2

[0036] (1) Take 0.5 g of citric acid and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0037] (2) Take 0.5 g of thioacetamide, 0.53 g of selenium powder, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 180 degrees Celsius for 12 hours.

[0038] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0039] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0040] The morphology of the material Figure 1 The battery was showcased in the exhibition. After 12 hours of aging following assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 367 cycles at a voltage of 0.01-3V and a current density of 5.0C, exhibited a discharge specific capacity of 24.91 mA hg. -1 The capacity retention rate was 5.08%.

[0041] Example 2

[0042] (1) Take 0.5 g of citric acid, 0.005 g of lithium chloride and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix it thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0043] (2) Take 0.5 g of thioacetamide, 0.53 g of selenium powder, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 180 degrees Celsius for 12 hours.

[0044] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0045] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0046] After 12 hours of aging following battery assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 500 cycles at a current density of 5.0C and a voltage range of 0.01-3V, exhibited a discharge specific capacity of 600.5 mA hg. -1 The capacity retention rate was 78.92%.

[0047] Example 3

[0048] (1) Take 0.5 g of citric acid, 0.01 g of lithium chloride and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix it thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0049] (2) Take 0.5 g of thioacetamide, 0.53 g of selenium powder, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 180 degrees Celsius for 24 hours.

[0050] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0051] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0052] After 12 hours of aging following battery assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 100 cycles at a voltage of 0.01-3V and a current density of 5.0C, exhibited a discharge specific capacity of 589.7 mA hg. -1 The capacity retention rate was 80.10%.

[0053] Example 4

[0054] (1) Take 0.5 g of citric acid, 0.01 g of lithium chloride and 50 ml of water to prepare a solution. Take a copper mesh sheet, put it into the solution, mix it thoroughly, and dry it in a forced-air oven at 120 degrees Celsius for 6 hours. After drying, calcine it at 800 degrees Celsius for 4 hours under H2+Ar (10%) atmosphere to obtain the pretreated current collector.

[0055] (2) Take 0.5 g of thioacetamide, 0.53 g of selenium powder, 2.5 g of hydrazine hydrate and 50 ml of ethylene glycol and mix them thoroughly. Add the pretreatment current collector to the mixture and mix thoroughly. Then transfer it to a polytetrafluoroethylene reactor and carry out a solvothermal reaction at 150 degrees Celsius for 12 hours.

[0056] (3) After the solvothermal reaction, the electrode is cleaned and dried. In an Ar glove box, molten lithium metal is heated at 250 degrees Celsius and the electrode is immersed in liquid lithium. The electrode is cooled at 25 degrees Celsius for 10 minutes to obtain a modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

[0057] CR2032 coin cells were assembled in a glove box filled with argon atmosphere, where both water and oxygen content were below 0.1 ppm. A 14 mm circular lithium sheet served as the electrode, and a modified three-dimensional copper framework electrode with composite lithium metal served as the other electrode. A 1 mol / L LiClO4 solution was used as the electrolyte, and a 16 mm diameter glass fiber membrane served as the separator.

[0058] After 12 hours of aging following battery assembly, charge-discharge tests were conducted at different potentials. The calcined sample, after 500 cycles at a current density of 5.0C under voltages ranging from 0.01 to 3V, exhibited a discharge specific capacity of 592.5 mA hg. -1 The capacity retention rate was 79.36%.

[0059] The above description is merely a basic explanation of the concept of this invention, and any equivalent modifications made based on the technical solution of this invention shall fall within the protection scope of this invention.

Claims

1. A method for preparing a modified three-dimensional copper framework lithium-ion battery anode material based on composite lithium metal, characterized in that, Includes the following steps: (1) The three-dimensional copper mesh frame is placed in an aqueous solution of citric acid and lithium salt in a certain proportion, heated and dried in a forced-air drying oven, and then calcined under a reducing atmosphere to obtain the pretreated current collector. (2) Disperse the pretreated current collector, sulfur source, selenium source and reducing agent obtained in (1) in an organic solvent in a certain proportion. After dispersion, place the dispersion in a polytetrafluoroethylene reactor for solvothermal reaction. (3) After the solvothermal reaction is completed, the copper mesh electrode is washed and dried, and the lithium metal is heated in an argon glove box. The copper mesh electrode is then immersed in liquid lithium and cooled to obtain the modified three-dimensional copper skeleton lithium battery anode material with composite lithium metal.

2. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The copper mesh mentioned in step (1) has a diameter of 12.0 mm and a thickness of 1.0 mm, wherein the copper wire has a diameter of 10-20 micrometers.

3. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The lithium salt mentioned in step (1) is lithium chloride, lithium nitrate or lithium oxalate, and the mass ratio of citric acid to lithium salt is 100:(5-1).

4. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The reducing atmosphere described in step (1) is H2+Ar (10%), the calcination temperature is 700-900 degrees Celsius, and the calcination time is 2-6 hours.

5. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The sulfur source mentioned in step (2) is sodium sulfide, thioacetamide or thiourea, the selenium source is selenium powder or selenium dioxide, the organic solvent is ethanol, ethylene glycol or glycerol, and the reducing agent is hydrazine hydrate or sodium borohydride.

6. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The sulfur source, selenium source and reducing agent mentioned in step (2) are in a certain ratio, namely the molar ratio of the three is 1:(0.9-1.1):(6-8).

7. The method for preparing a modified three-dimensional copper framework lithium battery anode material based on composite lithium metal according to claim 1, characterized in that, The solvothermal temperature mentioned in step (2) is 150-200 degrees Celsius for 8-24 hours.

8. The method for preparing a modified three-dimensional copper framework lithium-ion battery anode material based on composite lithium metal according to claim 1, characterized in that, The heating of molten lithium metal in step (3) is carried out at a heating temperature of 200-300 degrees Celsius, a cooling temperature of 25 degrees Celsius, and a cooling time of 5-10 minutes.

9. The modified three-dimensional copper framework lithium-ion battery anode material with composite lithium metal obtained by the preparation method according to any one of claims 1-8.

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