CN116247167A - 3D printing method for highly stable lithium metal electrodes that inhibit lithium dendrite growth - Google Patents

Abstract

The invention relates to a method for a high-stability lithium metal electrode for inhibiting growth of lithium dendrite through 3D printing, belonging to the technical field of energy materials; the method comprises the specific steps of printing a copper metal structure through a digital light processing technology, and using the copper metal structure after solidification and sintering treatment; assembling a Swagelok battery with a copper metal structure in a glove box filled with argon, wherein the 3D printed copper metal structure is a working electrode, a pure lithium sheet is a counter electrode or a reference electrode, a glass fiber film is a diaphragm, and a mixed solution of lithium bis (trifluoromethane) sulfonamide and 1, 3-dioxane/1, 2-dimethoxyethane is prepared as an electrolyte; the battery was then tested. The invention provides a large specific surface area by taking the 3D printing copper with a porous structure as the negative electrode current collector of the lithium metal battery, which is beneficial to increasing interface active sites and further reducing charge transfer resistance in electrochemical reaction, thereby reducing the possibility of lithium dendrite growth. The method solves the problem of lithium dendrite growth, improves the cycle safety and coulombic efficiency of the battery, and has simple process.

Description

3D printing method for highly stable lithium metal electrodes that inhibit lithium dendrite growth

technical field

The invention belongs to the technical field of energy materials, and in particular relates to a method for 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites.

Background technique

Lithium metal is an attractive anode material due to its extremely high specific capacity, extremely small potential, and low density. Lithium dendrites are metal microstructures formed on the anode and usually grow toward the cathode during battery charging. Once the dendrite connects the two electrodes, it will allow the current to pass, thereby heating the surrounding organic material and triggering an exothermic reaction, usually leading to thermal runaway. The uncontrollable growth of lithium dendrites will lead to serious safety issues and low Coulombic efficiency. hinders its application in next-generation secondary batteries. Through interface modification, adjusting the composition and three-dimensional morphology of negative electrode components is an important way to inhibit the growth of lithium dendrites. In terms of interface modification, it has been reported that converting the surface of nano-copper current collectors from Cu(111) crystal planes to formate-protected Cu(110) crystal planes can improve the oxidation resistance and lithium affinity of nanostructured copper current collectors. The current collector can uniformly deposit lithium under the conditions of high current density (3mA/cm ² ) and high capacity (6mAh/cm ² ), which alleviates the dendrite effect. It has been reported in the prior art to use seamless graphene-carbon nanotubes grown on copper substrates as a 3D framework to uniformly store lithium metal, and lithium metal will be distributed on the carbon nanotubes, thereby suppressing dendrite growth during plating and stripping . However, this method needs to consider growing graphene and carbon nanotubes first, which increases the experimental steps and costs.

If the three-dimensional morphology of the copper current collector is directly regulated, a three-dimensional structure current collector with layered pores and large electrode/electrolyte interface can be obtained, which can be used as the substrate of the negative active material on the one hand, and can provide sufficient diffusion on the other hand. channels, accelerate electron transfer and facilitate ion diffusion, reducing local current density. However, traditional manufacturing techniques cannot provide high-resolution printed parts with fine features and overhanging structures, and cannot meet the needs of manufacturing functional metal parts. For this requirement, 3D printing technologies, such as digital light processing technology, have the ability to realize printing customization. Characterized by complex structures, and has been widely used in the field of metal printing.

Contents of the invention

Technical problem to be solved:

In order to avoid the deficiencies of the prior art, the present invention provides a method of 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites. 3D printing copper with a porous structure provides a large The specific surface area is beneficial to increase the interfacial active sites and further reduce the charge transfer resistance in the electrochemical reaction, thereby reducing the possibility of Li dendrite growth. The problem of lithium dendrite growth is solved, the cycle safety and coulombic efficiency of the battery are improved, and the process is simple.

The technical solution of the present invention is: a method of 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites, characterized in that the specific steps are as follows:

Step 1. Print the copper metal structure through digital light processing technology, and use it after curing and sintering;

Step 2. Assemble the Swagelok battery with the copper metal structure in step 1 in a glove box filled with argon gas. The 3D printed copper metal structure is used as the working electrode, the pure lithium sheet is used as the counter electrode or reference electrode, and the glass fiber film is used as the separator , configuring a mixed solution of bis(trifluoromethane)sulfonamide lithium and 1,3-dioxane/1,2-dimethoxyethane as the electrolyte;

Step 3: Test the battery assembled in Step 2.

The further technical solution of the present invention is: in the step 1, the copper metal structure printing raw material is 1-3 wt% of 1,6-hexanediol diacrylate, isobornyl acrylate, trimethylolpropane ethyl Oxyacid triacryloyl acid, diphenyl-(2,4,6-trimethylbenzoyl) oxyphosphine and 20-30vol% copper sulfate pentahydrate powder.

The further technical solution of the present invention is: in the first step, the digital light processing technology prints the copper metal structure into a double helix structure, and then solidifies and sinters after printing. After 300°C and 400°C are kept at constant temperature for 5 hours respectively, continue to heat up to 1000-1400°C for 1-10 hours of annealing; the sintering requirement is to heat up at a heating rate of 5°C/min in a 3% hydrogen/argon environment To 600-800°C, the reaction time is 8 hours.

A further technical solution of the present invention is: in the second step, the diameter of the Swagelok battery is 13 mm, and an A/E grade glass fiber membrane with a particle retention rate of 1 μm is used as a separator, and the thickness is 0.3 mm.

The further technical solution of the present invention is: in the second step, the electrolyte solution is to dissolve 1M bis(trifluoromethane)sulfonamide lithium in 1,3-dioxane/1,2-dimethyl made from oxyethane.

A further technical solution of the present invention is: in the third step, the working electrode is activated to a capacity of 20 mA·h/cm ² under the condition of a current density of 2 mA/cm ² , and then within the voltage range of -1/+1V Stripping/plating at different current densities.

A further technical solution of the present invention is: in the third step, the coulombic efficiency is calculated by dividing the peelable capacity of each cycle by the lithium capacity plated on the working electrode.

A further technical solution of the present invention is: in the third step, use an Arbin LBT 2000-LNR battery testing device for testing.

Beneficial effect

The beneficial effects of the present invention are: the present invention discloses a 3D printed high-stability lithium metal electrode that inhibits the growth of lithium dendrites, and solves the growth problem of lithium dendrites by controlling the three-dimensional morphology of the negative electrode copper current collector. Improve battery cycle safety and coulombic efficiency, its advantages are as follows:

(1) Low overpotential and smooth voltage plateau: Thanks to the large specific surface area provided by the multi-level porous structure of 3D printed copper, in a symmetrical unit with a fixed area capacity of 20mA h/ ^cm2 , when the current density is 2mA / ^cm2 and 4mA/ ^cm2 , the symmetric battery with lithium@3D printed copper as the anode material showed low overpotential and stable voltage plateau over 560 hours of cycle life. The symmetrical battery using lithium@copper foil has died when the current density is 4mA/cm ² .

(2) Good stability: When the current density is 10mA/cm ² , the lithium@3D printed copper battery still shows good stability after more than 100 hours, and the overpotential is about 5mV (plating) ~ 4mV (stripping), However, there are large fluctuations in the lithium@copper foil battery, which proves that the 3D printed copper current collector has a good inhibitory effect on the growth of lithium dendrites.

(3) High Coulombic efficiency: At current densities of 2mA/cm ² , 4mA/cm ² , and 10mA/cm ² , the Li@3D printed copper battery exhibits a stable and high coulombic efficiency of 99.9% throughout the cycle life, proving The superiority of 3D printed copper current collectors.

Description of drawings

Figure 1 is the lithium plating/stripping curves of 3D printed copper and copper foil when the current density is 2mA/ ^cm2 and 4mA/ ^cm2 . The coating capacity is 20 mA·h/cm ² , and the duration is 550 hours.

Figure 2 is the lithium plating/stripping curve of 3D printed copper and copper foil when the current density is 10mA/ ^cm2 . The plating capacity is 20 mA·h/cm ² , and the duration is 100 hours.

Figure 3 shows the Coulombic efficiency of 3D printed copper and copper foil at current densities of 2mA/ ^cm2 and 4mA/ ^cm2 .

Figure 4 shows the Coulombic efficiency of 3D printed copper and copper foil at a current density of 10mA/ ^cm2 .

Detailed ways

The embodiments described below by referring to the figures are exemplary and are intended to explain the present invention and should not be construed as limiting the present invention.

Example 1:

Prepare the metal copper template for digital light curing, and perform curing and sintering treatment. Use 3D printed copper to assemble a Swagelok-type battery with a diameter of 13 mm in an argon-filled glove box. The 3D printed copper metal electrode is used as the working electrode, and the pure lithium sheet is used as the counter electrode or reference electrode. A/ Grade E glass fiber membrane was used as a separator (thickness 0.3mm), and 1M lithium bis(trifluoromethane)sulfonamide was dissolved in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1. Prepare the electrolyte solution with alkane, and then use the Arbin LBT 2000-LNR battery test device to test: 3D printing copper is used as the working electrode. Under the condition of the current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA·h/ ^cm2 for activation and stabilization, then stripping/plating at a current density of 2mA/ ^cm2 in the voltage range of -1/+1V, and calculate by dividing the strippable capacity per cycle by the lithium capacity plated on the working electrode Coulombic efficiency. The result of this embodiment is: it remains stable in the cycle test of more than 350 hours, shows low overpotential and smooth voltage plateau, and the calculated coulombic efficiency is 99.9%.

Example 2:

Prepare the metal copper template for digital light curing, and perform curing and sintering treatment. Use 3D printed copper to assemble a Swagelok-type battery with a diameter of 13 mm in an argon-filled glove box. The 3D printed copper metal electrode is used as the working electrode, and the pure lithium sheet is used as the counter electrode or reference electrode. A/ Grade E glass fiber membrane was used as a separator (thickness 0.3mm), and 1M lithium bis(trifluoromethane)sulfonamide was dissolved in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1. Prepare the electrolyte solution with alkane, and then use the Arbin LBT 2000-LNR battery test device to test: 3D printing copper is used as the working electrode. Under the condition of the current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA·h/ ^cm2 for activation and stabilization, then stripping/plating at a current density of 4mA/ ^cm2 in the voltage range of -1/+1V, and calculate by dividing the strippable capacity per cycle by the lithium capacity plated on the working electrode Coulombic efficiency. The results of this embodiment are: the coulombic efficiency is as high as 99.9% in a cycle test of more than 560 hours.

Example 3:

Prepare the metal copper template for digital light curing, and perform curing and sintering treatment. Use 3D printed copper to assemble a Swagelok-type battery with a diameter of 13 mm in an argon-filled glove box. The 3D printed copper metal electrode is used as the working electrode, and the pure lithium sheet is used as the counter electrode or reference electrode. A/ Grade E glass fiber membrane was used as a separator (thickness 0.3mm), and 1M lithium bis(trifluoromethane)sulfonamide was dissolved in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1. Prepare the electrolyte solution with alkane, and then use the Arbin LBT 2000-LNR battery test device to test: 3D printing copper is used as the working electrode. Under the condition of the current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA·h/ ^cm2 for activation and stabilization, then stripping/plating at a current density of 10mA/ ^cm2 in the voltage range of -1/+1V, and calculate by dividing the strippable capacity per cycle by the lithium capacity plated on the working electrode Coulombic efficiency. The results of this embodiment are: a stable voltage platform in a cycle test of more than 100 hours, and the coulombic efficiency is as high as 99.9% and remains stable.

Example 4:

Use copper foil to assemble a Swagelok-type battery with a diameter of 13 mm in an argon-filled glove box. The copper foil is used as the working electrode, and the pure lithium sheet is used as the counter electrode or reference electrode. A/E grade glass fiber with a particle retention rate of 1 μm is used. The membrane is used as a separator (thickness 0.3mm), and the electrolyte is prepared by dissolving 1M bis(trifluoromethane)sulfonamide lithium in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1 , and then use the Arbin LBT 2000-LNR battery test device to test: Copper foil is used as the working electrode, under the condition of current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA h/cm ² for activation and Stable, and then peel/plate at a current density of 2mA/ ^cm2 in the voltage range of -1/+1V, and calculate the coulombic efficiency by dividing the strippable capacity of each cycle by the lithium capacity plated on the working electrode. The results of this embodiment are: in the cycle test of more than 350 hours, there is a large overpotential with huge fluctuations, and the Coulombic efficiency is 99.9% at the beginning of the cycle, and cannot be kept stable as the number of cycles increases.

Example 5:

Use copper foil to assemble a Swagelok-type battery with a diameter of 13 mm in an argon-filled glove box. The copper foil is used as the working electrode, and the pure lithium sheet is used as the counter electrode or reference electrode. A/E grade glass fiber with a particle retention rate of 1 μm is used. The membrane is used as a separator (thickness 0.3mm), and the electrolyte is prepared by dissolving 1M bis(trifluoromethane)sulfonamide lithium in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1 , and then use the Arbin LBT 2000-LNR battery test device to test: 3D printed copper is used as the working electrode. Under the condition of current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA·h/cm ² for activation. And stable, then stripping/plating was carried out at a current density of 4mA/ ^cm2 in the voltage range of -1/+1V, and the Coulombic efficiency was calculated by dividing the strippable capacity per cycle by the lithium capacity plated on the working electrode. The results of this embodiment are: the lithium@copper foil battery cannot withstand the current density of 4mA/cm ² in the cycle test, and dies rapidly, and the coulombic efficiency is as low as 36.3%.

Embodiment 6:

The copper foil was assembled into a Swagelok-type battery with a diameter of 13 mm in a glove box filled with argon, the copper foil was used as the working electrode, and the pure lithium sheet was used as the counter electrode or reference electrode, and A/E grade glass fiber with a particle retention rate of 1 μm was used The membrane is used as a separator (thickness 0.3mm), and 1M bis(trifluoromethane)sulfonamide lithium is dissolved in 1,3-dioxane/1,2-dimethoxyethane according to the volume ratio of 1:1 to prepare the electrolyte , and then use the Arbin LBT 2000-LNR battery test device to test: 3D printed copper is used as the working electrode. Under the condition of current density of 2mA/cm ² , lithium is firstly electroplated from the electrode to a capacity of 20mA·h/cm ² for activation. And stable, then stripping/plating was carried out at a current density of 10mA/ ^cm2 in the voltage range of -1/+1V, and the Coulombic efficiency was calculated by dividing the strippable capacity of each cycle by the lithium capacity plated on the working electrode. The result of this embodiment is: in the cycle test, it died in less than 50 hours, and the voltage fluctuated greatly, and the coulombic efficiency was 58.7%.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be construed as limitations to the present invention. Variations, modifications, substitutions, and modifications to the above-described embodiments are possible within the scope of the present invention.

Claims (8)

1. a method for the high stability lithium metal electrode that suppresses lithium dendrite growth of 3D printing, is characterized in that concrete steps are as follows: Step 1. Print the copper metal structure through digital light processing technology, and use it after curing and sintering; Step 2. Assemble the Swagelok battery with the copper metal structure in step 1 in a glove box filled with argon gas. The 3D printed copper metal structure is used as the working electrode, the pure lithium sheet is used as the counter electrode or reference electrode, and the glass fiber film is used as the separator , configuring a mixed solution of bis(trifluoromethane)sulfonamide lithium and 1,3-dioxane/1,2-dimethoxyethane as the electrolyte; Step 3: Test the battery assembled in Step 2. 2. A method of 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites according to claim 1, characterized in that: in the step 1, the copper metal structure printing raw material is 1-3wt by mass percentage % of 1,6-hexanediol diacrylate, isobornyl acrylate, trimethylolpropaneethoxytriacrylic acid and diphenyl-(2,4,6-trimethylbenzoyl)oxy Phosphorus and 20-30vol% copper sulfate pentahydrate powder. 3. A method of 3D printing a highly stable lithium metal electrode that inhibits lithium dendrite growth according to claim 2, characterized in that: in the step 1, the copper metal structure printed by digital light processing technology is a double helix structure After the printing is finished, curing and sintering is carried out. The curing requirement is to raise the temperature to 200°C, 300°C, and 400°C at a heating rate of 1°C/min and keep the temperature at a constant temperature for 5 hours, and then continue to heat up to 1000-1400°C for 1-10 hours. ; The sintering requirement is to raise the temperature to 600-800°C at a heating rate of 5°C/min under 3% hydrogen/argon atmosphere, and the reaction time is 8 hours. 4. A method of 3D printing a highly stable lithium metal electrode that inhibits lithium dendrite growth according to any one of claims 1-3, characterized in that: in said step 2, the diameter of the Swagelok battery is 13mm, A grade A/E glass fiber membrane with a particle retention rate of 1 μm was used as a separator with a thickness of 0.3 mm. 5. according to claim 4, a kind of method of 3D printing high stability lithium metal electrode that inhibits lithium dendrite growth, is characterized in that: in described step 2, electrolytic solution is 1M bis(trifluoromethane) sulfonic acid Lithium amide is dissolved in 1,3-dioxane/1,2-dimethoxyethane at a volume ratio of 1:1. 6. According to claim 5, a method of 3D printing a highly stable ^lithium metal electrode that inhibits the growth of lithium dendrites is characterized in that: in the step 3, the working electrode is 2mA/cm at a current density , activated to a capacity of 20mA·h/cm ² , and then stripped/plated at different current densities in the voltage range of -1/+1V. 7. A method of 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites according to claim 6, characterized in that: in the step 3, divide the peelable capacity of each cycle by the plated The lithium capacity on the working electrode was used to calculate the Coulombic efficiency. 8. A method of 3D printing a highly stable lithium metal electrode that inhibits the growth of lithium dendrites according to claim 7, characterized in that: in step 3, the Arbin LBT 2000-LNR battery testing device is used for testing.

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