A method for inhibiting high-temperature gas production in lithium-carbon fluoride batteries

Abstract

The present invention discloses a method for suppressing high-temperature gas production of a lithium fluorinated carbon battery. The method comprises preparing a porous electrode slurry, specifically mixing an electrode material, a conductive agent, a binder, an emulsifier, a first pore-forming agent, a dispersant, and a solvent; performing ultrasonic treatment and high-speed centrifugal dispersion; and then simultaneously performing high-speed stirring and high-speed dispersion. The stirring paddle is then reversed under vacuum conditions to obtain a positive electrode slurry, which is uniformly coated on a current collector, and sequentially subjected to programmed drying and hot rolling to obtain a porous fluorinated carbon electrode. The method also comprises preparing a high-porosity diaphragm. The present invention adopts a porous fluorinated carbon electrode and a high-porosity diaphragm to effectively lock the electrolyte inside the battery, reduce the saturated vapor pressure of the electrolyte solvent inside the battery, increase the boiling point of the solvent, and effectively suppress the problem of high-temperature gas production of the lithium fluorinated carbon battery. On the basis of ensuring the room-temperature performance of the lithium fluorinated carbon battery, the high-temperature discharge capacity of the lithium fluorinated carbon battery is improved and the problem of high-temperature swelling is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of production and processing of lithium primary batteries, and in particular relates to a method for inhibiting high-temperature gas production in lithium carbon fluoride batteries. Background Art

[0002] A primary lithium battery (also known as a lithium battery) is a high-energy chemical battery. It uses metallic lithium as the negative electrode, a solid salt or a salt dissolved in an organic solvent as the electrolyte, and a metal oxide or other solid or liquid oxidant as the positive electrode active material. Commonly used round lithium manganese dioxide (Li / MnO2) batteries and lithium fluoride carbon (Li / (CFx)n) batteries are designated by the letters CR and BR, respectively, followed by a number indicating the battery model. Lithium primary batteries are the general term for this family of chemical power sources that use metallic lithium as the negative electrode material.

[0003] Lithium carbon fluoride batteries are high-energy-density primary batteries with a practical specific energy of 250-700 Wh / kg, several times that of dry cell batteries. They are also easily miniaturized and lightweight. Because carbon fluoride materials are highly stable, lithium carbon fluoride batteries maintain high capacity at high temperatures, experiencing virtually no degradation. Carbon fluoride is a compound formed by the reaction of various forms of carbon with fluorine gas. While electrochemically active, it exhibits high chemical stability in organic electrolytes and resists thermal decomposition at temperatures up to 500°C. This results in a long storage life and excellent high-temperature performance. However, because lithium carbon fluoride batteries use organic electrolytes and generate heat during discharge, they can experience electrolyte vaporization and gassing at high temperatures. Without electrolyte optimization, the safe operating temperature of lithium carbon fluoride batteries is below 60°C, and their thermal stability is below 90°C. While electrolyte optimization can improve the temperature resistance of lithium carbon fluoride batteries, this inevitably results in a decrease in battery performance.

[0004] With the rapid development of technologies in portable electronic devices, precision medicine, aerospace, and other fields, there is an urgent need for high-power, high-energy-density, and highly safe lithium primary chemical power sources. Currently, lithium-carbon fluoride batteries (LCF) face technical challenges such as severe heat generation and poor heat resistance. Researchers at home and abroad have improved the heat resistance of LCF batteries through electrolyte optimization and other methods. While this has effectively improved the heat resistance of LCF batteries, the battery's discharge rate is very low, at only 0.02°C, and its room-temperature performance is significantly worse than its high-temperature performance.

[0005] Although the patent with publication number CN112670528A discloses a method for preparing a high-rate primary alkali metal battery, the worm graphite is shear-emulsified and homogenized to obtain graphite micro-sheets, and then high-temperature fluorination is performed with the assistance of alloy balls to obtain fluorinated graphite micro-sheets. The fluorinated graphite micro-sheets are used as active materials, dissolved in proportion with a conductive agent and a binder, slurried and coated on a current collector, and cut after drying to obtain a battery positive electrode; wherein the surface C=C bond ratio of the fluorinated graphite micro-sheets is 5-15%; the metal sodium block is Or remove the surface passivation layer of the metal potassium block, then add some electrolyte, and through mechanical action, roll and cut it into a metal sodium sheet or metal potassium sheet of the first size as the battery negative electrode; assemble the battery positive electrode, battery negative electrode, separator, and electrolyte to obtain a sodium / graphite fluoride micron sheet primary battery or a potassium / graphite fluoride micron sheet primary battery; it has a high discharge rate and the battery can be discharged in a wide temperature range of -30°C to 100°C. However, this technical solution cannot solve the problem of high heat generation and gas production of lithium carbon fluoride batteries when working at high temperatures.

[0006] Therefore, it is crucial to study a lithium carbon fluoride battery that has high discharge rate, low heat generation and small gas production. Summary of the Invention

[0007] In response to the deficiencies in the prior art, the present invention proposes a method for inhibiting high-temperature gas production in lithium carbon fluoride batteries. The present invention aims to use porous carbon fluoride electrodes and ceramic diaphragms coated with a high-porosity carbon layer to effectively lock the electrolyte inside the battery, reduce the saturated vapor pressure of the electrolyte solvent inside the battery, increase the boiling point of the solvent, and effectively inhibit the problem of high-temperature gas production in lithium carbon fluoride batteries. On the basis of ensuring the room-temperature performance of lithium carbon fluoride batteries, the high-temperature discharge capacity of lithium carbon fluoride batteries is improved, and the problem of high-temperature swelling of the batteries is solved.

[0008] This is achieved specifically through the following technical solutions:

[0009] A method for inhibiting high-temperature gas production in lithium-carbon fluoride batteries comprises the following steps:

[0010] Step 1: Prepare a porous electrode slurry: prepare a binder into a 6%-10% glue solution to obtain glue solution 1; mix the electrode material and the conductive agent according to the mass ratio, first ultrasonically treat for 1 hour, and then disperse at high speed centrifugation for 30 minutes to obtain mixture 2; prepare the dispersant into an 8%-10% dilution to obtain dispersion 3; then transfer the glue solution 1 and mixture 2 into a blender for high-speed stirring and dispersion for 1-2 hours; then add the dispersion 3 into a stirring tank for high-speed stirring and dispersion for 0.5-1 hour to obtain a slurry with a viscosity of 50,000±500mPa·s; then add an emulsifier, a first pore-forming agent, and a solvent, continue high-speed stirring and dispersion for 6 to 8 hours to obtain a slurry with a viscosity of 20,000±500mPa·s; finally, reverse the stirring paddle under vacuum conditions, stir at a speed of 30r / min, and for 30 minutes to obtain a positive electrode slurry with a viscosity of 11,000±500mPa·s; the dispersant is a modified amino alcohol;

[0011] Step 2: preparing a porous electrode precursor: uniformly coating the positive electrode slurry prepared in step 1 on a microporous aluminum foil current collector at a coating speed of 1-2 m / min, and subjecting the product to programmed drying to obtain a porous electrode precursor having a solvent residue of 6-10%; the programmed drying comprises drying by increasing the temperature in stages and then drying by decreasing the temperature in stages;

[0012] Step 3: preparing a porous electrode: hot rolling the porous electrode precursor obtained in step 2, performing a first gradient rolling operation at a pressure of 0.5 MPa-1.0 MPa, a rolling temperature of 80-90° C., and a speed of 0.5 m / s-1 m / s; then heating the temperature to 120-130° C. and performing a second gradient rolling operation, performing a rolling operation once at a speed of 0.5 m / s-1 m / s, to obtain a porous fluorinated carbon electrode with a gradient pore distribution;

[0013] Step 4: Prepare a high-porosity diaphragm: Use an extrusion coating method to apply a single-walled carbon nanotube slurry with a viscosity of 2000-3000 mPa·s to the non-ceramic surface of the ceramic diaphragm to a coating thickness of 0.5-1.0 μm. The diaphragm is baked at 150°C under vacuum conditions for 4-6 hours to obtain a high-porosity carbon-coated ceramic diaphragm;

[0014] Step 5: preparing a high-efficiency current-collecting negative electrode: cutting the metal lithium strip into a specified size, and welding the nickel strip and the metal lithium by ultrasonic welding to obtain a negative electrode sheet;

[0015] Step 6: Battery assembly: Assemble the porous fluorinated carbon electrode, negative electrode sheet, and high-porosity carbon-coated ceramic diaphragm obtained in steps 3, 4, and 5, encapsulate them in a battery housing, and seal the battery cover and housing by laser welding;

[0016] Step 7: Injection: Inject the electrolyte into the battery using vacuum injection;

[0017] Step 8: Seal: Seal the liquid filling port with a steel nail.

[0018] Furthermore, in the slurry with a viscosity of 20000±500 mPa·s in step 1, the mass ratio of the electrode material, the conductive agent, the binder, the emulsifier, the first pore-forming agent, the dispersant, and the solvent is 0.9:0.03:0.01:0.02:0.02:0.02:1.0.

[0019] Furthermore, in step 1, the electrode material is one or more of graphite fluoride, carbon fluoride, carbon fluoride nanotubes, graphene fluoride, carbon fluoride nanofibers, and nano-carbon fluoride.

[0020] Furthermore, in step 1, the conductive agent is composed of silver nanowires and any one of SP, CNT, and graphene in a mass ratio of (1-1.5):1.

[0021] Furthermore, in step 1, the binder is composed of PVDF900 and PVDF5130 in a mass ratio of 1:(1-1.2).

[0022] Furthermore, in step 1, the emulsifier is PTFE emulsion.

[0023] Furthermore, in step 1, the pore-forming agent is NH4HCO3.

[0024] Furthermore, in step 1, the modified amino alcohol is any one of 2-aminoisobutanol, 2-dimethylamino-2-methyl-1-propanol, and 2-amino-1-butanol, or a combination thereof.

[0025] Furthermore, in step 1, the rotation speed of the high-speed stirring in the stirrer is 300-500 r / min, and the rotation speed of the high-speed dispersion is 5000-6000 r / min.

[0026] Furthermore, in step 1, the stirring paddle is reversed at a stirring speed of 30 r / min for 30 min.

[0027] Furthermore, in step 2, the programmed drying is carried out in sequence at 50°C, 52°C, 55°C, 52°C, and 48°C; the present invention takes into account the hydrophobic and solvent-repellent properties of the fluorinated carbon material, and therefore adopts staged temperature increase drying in the early stage of drying and temperature reduction drying in the later stage, which has the advantages of uniform distribution of pores inside the electrode and inhibition of adhesive floating.

[0028] Furthermore, in step 3, the microporous aluminum foil has a pore size of 20 μm-35 μm and a porosity of 15%-17%.

[0029] Furthermore, in step 3, the porous fluorinated carbon electrode has a pore size of 0.2-0.5 μm and a porosity of 75%-80%.

[0030] Furthermore, in step 4, the ceramic diaphragm with high porosity and carbon coating has a porosity range of 65%-75% and a thickness of 16-25 μm.

[0031] Furthermore, in step 7, the vacuum degree of the vacuum injection is -0.07 kPa to -0.08 kPa, and the holding time is 20-30 minutes.

[0032] In step 4, the high-porosity carbon-coated ceramic diaphragm has a carbon-coated layer on one side and a ceramic layer on the other side.

[0033] In step 6, the carbon-coated layer of the high-porosity carbon-coated ceramic separator completely covers the negative electrode, and the ceramic layer completely covers the positive electrode.

[0034] Beneficial effects:

[0035] (1) The present invention adopts a porous fluorinated carbon electrode, which improves the liquid absorption rate of the electrode, effectively locks the electrolyte inside the electrode, reduces the saturated vapor pressure of the electrolyte solvent, effectively increases the boiling point of the electrolyte solvent inside the battery, and reduces the gas production of the battery at high temperature.

[0036] (2) The present invention adopts a ceramic diaphragm coated with a high porosity carbon layer, which improves the liquid absorption rate of the diaphragm, effectively locks the electrolyte inside the diaphragm, reduces the saturated vapor pressure of the electrolyte solvent, effectively increases the boiling point of the electrolyte solvent inside the battery, and reduces the gas production of the battery at high temperature.

[0037] (3) The present invention improves the high-temperature capacity of the lithium fluorinated carbon battery by using a porous carbon fluoride electrode and a ceramic diaphragm with a high-porosity carbon coating, which not only ensures the room-temperature performance and rate performance of the lithium fluorinated carbon battery, but also effectively reduces the gas production of the battery at high temperatures.

[0038] (4) The porous carbon fluoride electrode and the high-porosity carbon-coated ceramic diaphragm of the present invention are applied to lithium carbon fluoride batteries, which not only improves the battery's room temperature discharge capacity, but also effectively improves the high-temperature capacity of the lithium carbon fluoride battery, with significant results. The discharge capacity of the lithium carbon fluoride battery at 90°C is increased to 2.57Ah, and the discharge rate is as high as 0.5C. When stored at 149°C, the battery does not swell or discharge. The lithium carbon fluoride battery prepared by the present invention has excellent high-temperature performance and heat stability up to 149°C. Compared with the method of suppressing high-temperature gas production of lithium carbon fluoride batteries by optimizing the electrolyte, the method of the present invention effectively improves the high-temperature discharge capacity of lithium carbon fluoride batteries and solves the problems of high-temperature gas production and swelling of batteries on the basis of ensuring room temperature performance.

[0039] (5) In the present invention, the modified amino alcohol has both dispersing and pore-forming functions. On the one hand, the modified amino alcohol makes the active material carry an electric charge, and active materials with the same charge repel each other, reducing the agglomeration of the active material and improving the uniformity of dispersion. Therefore, it can be used as a dispersant. On the other hand, the modified amino alcohol will volatilize during the hot rolling process, forming a pore structure with a second gradient distribution inside the electrode. Therefore, it can be used as a pore-forming agent, so that the rolling and pore-forming are carried out simultaneously when the porous electrode precursor is hot rolled. In addition, the modified amino alcohol is a high-concentration liquid. Direct contact with PVDF binder powder or high-concentration PVDF glue will destroy the adhesion of PVDF. The present invention solves the problem of modified amino alcohol reducing the adhesion of PVDF by preferentially configuring low-concentration PVDF glue and modified amino alcohol dispersion. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 The discharge curves of the lithium carbon fluoride battery obtained in Example 1 and the lithium carbon fluoride battery obtained in Comparative Example 1 at an operating temperature of 90° C.

[0041] Figure 2 The figures are discharge curves of the lithium carbon fluoride battery obtained in Example 1 and the lithium carbon fluoride battery obtained in Comparative Example 1 under normal temperature conditions. DETAILED DESCRIPTION

[0042] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments. Any improvement or replacement based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0043] The technical solutions of the embodiments of the present invention are as follows:

[0044] A method for inhibiting high-temperature gas production in lithium-carbon fluoride batteries comprises the following steps:

[0045] Step 1: Prepare porous electrode slurry: prepare the binder into a 6%-10% glue solution to obtain glue solution 1; mix the electrode material and the conductive agent according to the mass ratio, first ultrasonically treat for 1 hour, and then disperse at high speed centrifugation for 30 minutes to obtain mixture 2; prepare the dispersant into an 8%-10% dilution to obtain dispersion 3; then transfer the glue solution 1 and mixture 2 into a blender for high-speed stirring and dispersion for 1-2 hours; then add the dispersion 3 into the stirring tank and stir and disperse at high speed for 0.5-1 hour to obtain a viscosity of 50000±50 0mPa·s slurry; then add an emulsifier, a first pore-forming agent, and a solvent, continue high-speed stirring and dispersion, time 6 to 8h, to obtain a slurry with a viscosity of 20000±500mPa·s; finally, reverse the stirring paddle under vacuum conditions, stirring speed 30r / min, time 30min, to obtain a positive electrode slurry with a viscosity of 11000±500mPa·s; the dispersant is a modified amino alcohol, specifically any one or a combination of 2-aminoisobutanol, 2-dimethylamino-2-methyl-1-propanol, and 2-amino-1-butanol;

[0046] Step 2: preparing a porous electrode precursor: uniformly coating the positive electrode slurry prepared in step 1 on a microporous aluminum foil current collector at a coating speed of 1-2 m / min, and subjecting the product to programmed drying to obtain a porous electrode precursor having a solvent residue of 6-10%; the programmed drying comprises drying by increasing the temperature in stages and then drying by decreasing the temperature in stages;

[0047] Step 3: preparing a porous electrode: hot rolling the porous electrode precursor obtained in step 2, performing a first gradient rolling operation at a pressure of 0.5 MPa-1.0 MPa, a rolling temperature of 80-90° C., and a speed of 0.5 m / s-1 m / s; then heating the temperature to 120-130° C. and performing a second gradient rolling operation, performing a rolling operation once at a speed of 0.5 m / s-1 m / s, to obtain a porous fluorinated carbon electrode with a gradient pore distribution;

[0048] Step 4: Prepare a high-porosity diaphragm: Use an extrusion coating method to apply a single-walled carbon nanotube slurry with a viscosity of 2000-3000 mPa·s to the non-ceramic surface of the ceramic diaphragm to a coating thickness of 0.5-1.0 μm. The diaphragm is baked at 150°C under vacuum conditions for 4-6 hours to obtain a high-porosity carbon-coated ceramic diaphragm;

[0049] Step 5: preparing a high-efficiency current-collecting negative electrode: cutting the metal lithium strip into a specified size, and welding the nickel strip and the metal lithium by ultrasonic welding to obtain a negative electrode sheet;

[0050] Step 6: Battery assembly: Assemble the porous fluorinated carbon electrode, negative electrode sheet, and high-porosity carbon-coated ceramic diaphragm obtained in steps 3, 4, and 5, encapsulate them in a battery housing, and seal the battery cover and housing by laser welding;

[0051] Step 7: Injection: Inject the electrolyte into the battery using vacuum injection;

[0052] Step 8: Seal: Use a steel nail to seal the liquid injection port;

[0053] In the slurry with a viscosity of 20000±500 mPa·s in step 1, the mass ratio of the electrode material, the conductive agent, the binder, the emulsifier, the first pore-forming agent, the dispersant, and the solvent is 0.9:0.03:0.01:0.02:0.02:0.02:1.0.

[0054] Furthermore, in step 1, the electrode material is one or more of graphite fluoride, carbon fluoride, carbon fluoride nanotubes, graphene fluoride, carbon fluoride nanofibers, and nanocarbon fluoride;

[0055] Furthermore, in step 1, the conductive agent is composed of silver nanowires and any one of SP, CNT, and graphene in a mass ratio of (1-1.5):1; the conductive agent selected by the present invention includes at least silver nanowires, which can improve the conductivity of the carbon fluoride electrode and reduce the heat generation of the lithium carbon fluoride battery;

[0056] Furthermore, in step 1, the binder is composed of PVDF900 and PVDF5130 in a mass ratio of 1: (1-1.2);

[0057] Furthermore, in step 1, the emulsifier is a PTFE emulsion. PTFE is used as an emulsifier mainly because PTFE has high temperature resistance and adhesive properties, and works synergistically with PVDF900 and PVDF5130 to ensure that positive electrode components such as carbon fluoride maintain good adhesion with the current collector under high temperature conditions such as 149°C, thereby preventing them from falling off.

[0058] Furthermore, in step 1, the first pore-forming agent is NH4HCO3, and the dispersant-modified amino alcohol serves as the second pore-forming agent. During the electrode preparation and roller pressing process, the NH4HCO3 and the modified amino alcohol sequentially decompose and volatilize, forming a gradient pore distribution within the electrode, which has the excellent effect of a gradient pore distribution. Compared to methanol, it is non-toxic and harmless.

[0059] Furthermore, in step 1, the rotation speed of the high-speed stirring is 300-500 r / min, and the rotation speed of the high-speed dispersion is 5000-6000 r / min. The present invention performs high-speed stirring and high-speed dispersion on the mixture, which can make the substances in the slurry evenly dispersed, improve the interface contact, and thus have the advantage of uniform dispersion. However, if only high-speed stirring is used, uniform dispersion cannot be achieved; if only high-speed dispersion is used, the material will be too fine and agglomerated. Through the combination of this stirring method, the time required for uniform dispersion is also saved.

[0060] Furthermore, in step 3, the microporous aluminum foil has a pore size of 0.2 mm to 0.35 mm and a porosity of 15% to 17%.

[0061] Furthermore, in step 3, the porous fluorinated carbon electrode has a pore size of 0.2-0.3 μm and a porosity of 75%-80%;

[0062] Furthermore, the high-porosity carbon-coated ceramic diaphragm in step 4 has a porosity range of 65%-75% and a thickness of 16-25 μm;

[0063] The present invention controls the porosity of the porous fluorinated carbon electrode and the diaphragm to reduce the saturated vapor pressure of the electrolyte solvent;

[0064] Furthermore, in step 4, the high-porosity carbon-coated ceramic diaphragm has a carbon-coated layer on one side and a ceramic layer on the other side;

[0065] Furthermore, in step 6, the carbon-coated layer of the high-porosity carbon-coated ceramic separator completely covers the negative electrode, and the ceramic layer completely covers the positive electrode;

[0066] Furthermore, in step 7, the vacuum degree of the vacuum injection is -0.07 kPa to -0.08 kPa, and the holding time is 20-30 minutes.

[0067] Example 1

[0068] A method for inhibiting high-temperature gas production in lithium-carbon fluoride batteries comprises the following steps:

[0069] Step 1: Prepare porous electrode slurry: prepare the binder into 8% glue to obtain glue 1; mix the electrode material and the conductive agent according to the mass ratio, first ultrasonically treat for 1 hour, and then disperse at high speed centrifugation for 30 minutes to obtain mixture 2; prepare the dispersant into a 10% dilution to obtain dispersion 3; then transfer the glue 1 and mixture 2 into a blender for high-speed stirring and dispersion for 1.5 hours; then add the dispersion 3 into the stirring tank for high-speed stirring and dispersion for 0.5 hours to obtain a slurry with a viscosity of 50,000 ± 500 mPa·s; then add the emulsifier, pore-forming agent, and solvent, continue to stir and disperse at high speed for 6 hours to obtain a slurry with a viscosity of 20,000 ± 500 mPa·s; finally, reverse the stirring paddle under vacuum conditions, stir at a speed of 30 r / min, and for 30 minutes n, to obtain a positive electrode slurry with a viscosity of 11000±500mPa·s; wherein the electrode material is carbon fluoride; the conductive agent is composed of nanosilver wire and SP in a mass ratio of 1:1; the binder is composed of PVDF900 and PVDF5130 in a mass ratio of 1:1; the speed of the high-speed stirring is 300r / min, and the speed of the high-speed dispersion is 6000r / min; the dispersant is 2-aminoisobutanol; the first pore-forming agent is NH4HCO3; the emulsifier is PTFE emulsion; the mass ratio of the electrode material, conductive agent, binder, emulsifier, pore-forming agent, dispersant, and solvent in the slurry with a viscosity of 20000±500mPa·s is 0.9:0.03:0.01:0.02:0.02:0.02:1.0;

[0070] Step 2: Preparation of porous electrode precursor: Select a microporous aluminum foil group with a pore size of 20 μm and a porosity of 15%-17% as the current collector, and evenly coat the slurry prepared in step 1 on the microporous aluminum foil current collector. Then, dry it in an oven at 50°C, 52°C, 55°C, 52°C, and 48°C in sequence, with a coating speed of 1 m / min, to obtain a porous electrode precursor with a solvent residue of 6%;

[0071] Step 3: preparing a porous electrode: hot rolling the porous electrode precursor obtained in step 2, with the first gradient rolling being performed at a pressure of 0.5 MPa, a rolling temperature of 80° C., and a speed of 0.5 m / s; then heating to 120° C. and performing a second gradient rolling, with the rolling number being 1 time and a speed of 0.5 m / s, to obtain a porous fluorinated carbon electrode with a pore size of 0.2 μm and a porosity of 75%;

[0072] Step 4: Prepare a high-porosity diaphragm: Use an extrusion coating method to apply a single-walled carbon nanotube slurry with a viscosity of 2000 mPa·s to the non-ceramic surface of the ceramic diaphragm, with a carbon coating thickness of 0.5 μm. The diaphragm is baked at 150°C under vacuum conditions for 4 hours to obtain a high-porosity carbon-coated ceramic diaphragm with a porosity range of 65% and a thickness of 16 μm. The high-porosity carbon-coated ceramic diaphragm has a carbon coating layer on one side and a ceramic layer on the other side.

[0073] Step 5: preparing a high-efficiency current-collecting negative electrode: cutting the metal lithium strip into a specified size, and welding the nickel strip and the metal lithium by ultrasonic welding to obtain a negative electrode sheet;

[0074] Step 6: Battery assembly: Assemble the porous fluorinated carbon electrode, negative electrode sheet, and separator obtained in steps 3, 4, and 5, encapsulate them in a battery housing, and seal the battery cover and housing by laser welding. During assembly, the carbon coating layer of the separator must completely cover the negative electrode, and the ceramic layer must completely cover the positive electrode.

[0075] Step 7: Inject the electrolyte into the battery using vacuum injection at a vacuum degree of -0.07 kPa for 20 minutes.

[0076] Step 8: Seal: Seal the liquid filling port with a steel nail.

[0077] Comparative Example 1

[0078] A method for inhibiting high-temperature gas production in lithium-carbon fluoride batteries comprises the following steps:

[0079] Step 1: Prepare an electrode slurry: Mix carbon fluoride, a conductive agent, a binder, and a solvent in a mass ratio of 0.9:0.03:0.04:1.0, first ultrasonically treat for 30 minutes, and then high-speed centrifugal disperse for 30 minutes to obtain a slurry with a viscosity of 50,000 ± 500 MPa s, then transfer it to a blender, and simultaneously add a solvent of 10% of the total mass of the electrode material, conductive agent, and binder for high-speed stirring and high-speed dispersion. The total time for high-speed stirring and high-speed dispersion is 4 hours to obtain a slurry with a viscosity of 20,000 ± 500 MPa s. Finally, the stirring paddle is reversed under vacuum conditions, the stirring speed is 30 r / min, and the time is 30 minutes to obtain a positive electrode slurry; wherein, the electrode material, conductive agent, binder, first pore-forming agent, and emulsifier are the same as those in Example 1; the speed of the high-speed stirring is 500 r / min, and the speed of the high-speed dispersion is 6000 r / min;

[0080] Step 2: Preparation of porous electrode precursor: Select a microporous aluminum foil group with a pore size of 20 μm and a porosity of 15%-17% as the current collector, and evenly coat the slurry prepared in step 1 on the microporous aluminum foil current collector. Then, dry it in an oven at 50°C, 52°C, 55°C, 52°C, and 48°C in sequence, with a coating speed of 1 m / min, to obtain a porous electrode precursor with a solvent residue of 6%;

[0081] Step 3: preparing an electrode: hot rolling the electrode precursor obtained in step 2 at a pressure of 0.5 MPa, a rolling temperature of 80° C., and one rolling cycle to obtain a fluorinated electrode;

[0082] Step 4: Battery assembly: Assemble the carbon fluoride electrode, negative electrode sheet, and ceramic diaphragm together, encapsulate them in a battery housing, and seal the battery cover and housing by laser welding; the ceramic diaphragm has a ceramic layer on one side and a non-ceramic layer on the other side. During assembly, the non-ceramic layer of the diaphragm is required to completely cover the negative electrode, and the ceramic layer is required to completely cover the positive electrode;

[0083] Step 5: Inject the electrolyte into the battery using vacuum injection at a vacuum degree of -0.07 kPa for 20 minutes.

[0084] Step 6: Seal: Seal the liquid filling port with a steel nail.

[0085] Comparative Example 2

[0086] On the basis of Example 1, a porous fluorinated carbon electrode with a porosity of 70% was produced by reducing the amount of pore-forming agent, that is, adjusting the ratio of electrode material, conductive agent, binder, emulsifier, first pore-forming agent, dispersant, and solvent to 0.9:0.03:0.02:0.02:0.01:0.02:1.0.

[0087] Comparative Example 3

[0088] On the basis of Example 1, by improving the drying settings, the slurry prepared in step 1 is evenly coated on the microporous aluminum foil current collector, and the oven temperatures are set to 50°C, 52°C, 55°C, 57°C, 55°C, 52°C, and 48°C in sequence to obtain a porous electrode precursor with a solvent residue of 5%, and produce a porous fluorinated carbon electrode with a porosity of 85%.

[0089] Comparative Example 4

[0090] Based on Example 1, the porosity of the separator was controlled to be 60%.

[0091] Comparative Example 5

[0092] Based on Example 1, the porosity of the separator was controlled to be 80%.

[0093] Example 2

[0094] A method for inhibiting high-temperature gas production in lithium carbon fluoride batteries. Based on Example 1, carbon fluoride is replaced with graphite fluoride, and the dispersant is 2-dimethylamino-2-methyl-1-propanol; the conductive agent is composed of silver nanowires and carbon nanotubes in a ratio of 1:1; and the binder is composed of PVDF900 and PVDF5130 in a ratio of 1:1.2.

[0095] Example 3

[0096] A method for inhibiting high-temperature gas production in lithium carbon fluoride batteries. Based on Example 1, carbon fluoride is replaced with carbon fluoride nanotubes, and the dispersant is 2-amino-1-butanol; the conductive agent is composed of nanosilver wires and graphene in a ratio of 1.5:1; and the binder is composed of PVDF900 and PVDF5130 in a ratio of 1:1.1.

[0097] Example 4

[0098] A method for inhibiting high-temperature gas production in a lithium carbon fluoride battery. Based on Example 1, the carbon fluoride is replaced with fluorinated graphene; the dispersant is a mixture of 2-aminoisobutanol, 2-dimethylamino-2-methyl-1-propanol, and 2-amino-1-butanol in equal weight ratios; and the conductive agent is composed of nanosilver wires and SP in a ratio of 1.4:1.

[0099] Example 5

[0100] A method for inhibiting high-temperature gas production in lithium carbon fluoride batteries. Based on Example 1, carbon fluoride is replaced with carbon fluoride nanofibers; the dispersant is a mixture of 2-aminoisobutanol and 2-dimethylamino-2-methyl-1-propanol in an equal mass ratio; and the conductive agent is composed of nanosilver wires and carbon nanotubes in a mass ratio of 1.2:1.

[0101] Example 6

[0102] A method for inhibiting high-temperature gas production in a lithium carbon fluoride battery is disclosed. The method comprises replacing carbon fluoride with nano carbon fluoride based on Example 1; and the conductive agent comprises nano silver wire and graphene in a mass ratio of 1.3:1.

[0103] The discharge performance of each group at 90°C is shown in the following table:

[0104]

[0105]

Claims

1. A method for inhibiting high-temperature gas production in lithium fluoride carbon batteries, characterized in that: The steps include: Step 1: Prepare a porous electrode slurry: prepare a binder into a 6%-10% glue solution to obtain glue solution 1; mix the electrode material and the conductive agent according to the mass ratio, first ultrasonically treat for 1 hour, and then disperse at high speed centrifugation for 30 minutes to obtain mixture 2; prepare the dispersant into an 8%-10% dilution to obtain dispersion 3; then transfer the glue solution 1 and mixture 2 into a blender for high-speed stirring and dispersion for 1-2 hours; then add the dispersion 3 into a stirring tank for high-speed stirring and dispersion for 0.5-1 hour to obtain a slurry with a viscosity of 50,000±500mPa·s; then add an emulsifier, a first pore-forming agent, and a solvent, continue high-speed stirring and dispersion for 6 to 8 hours to obtain a slurry with a viscosity of 20,000±500mPa·s; finally, reverse the stirring paddle under vacuum conditions, stir at a speed of 30r / min, and for 30 minutes to obtain a positive electrode slurry with a viscosity of 11,000±500mPa·s; the dispersant is a modified amino alcohol; The mass ratio of the electrode material, the conductive agent, the binder, the emulsifier, the first pore-forming agent, the dispersant, and the solvent in the slurry having a viscosity of 20,000 ± 500 mPa·s is 0.9:0.03:0.01:0.02:0.02:0.02:1.0; Step 2: preparing a porous electrode precursor: uniformly coating the positive electrode slurry prepared in step 1 on a microporous aluminum foil current collector at a coating speed of 1 to 2 m / min, and subjecting the slurry to programmed drying to obtain a porous electrode precursor; the programmed drying comprises drying by increasing the temperature in stages and then drying by decreasing the temperature in stages to obtain a porous electrode precursor; Step 3: preparing a porous electrode: hot rolling the porous electrode precursor obtained in step 2, with the first gradient rolling being performed once at a pressure of 0.5 MPa-1.0 MPa, a rolling temperature of 80-90° C., and a speed of 0.5 m / s-1 m / s; After heating to 120-130° C., a second gradient rolling process is performed, with the rolling frequency of 1 time and a speed of 0.5 m / s-1 m / s, to obtain a porous fluorinated carbon electrode with a gradient pore distribution; the porous fluorinated carbon electrode has a porosity of 75%-80%; Step 4: preparing a high-porosity diaphragm: applying a single-walled carbon nanotube slurry with a viscosity of 2000-3000 mPa·s to the non-ceramic surface of the ceramic diaphragm by an extrusion coating method to a coating thickness of 0.5 to 1.0 μm, and baking the diaphragm at 150° C. under vacuum conditions for 4 to 6 hours to obtain a high-porosity carbon-coated ceramic diaphragm; the porosity of the high-porosity carbon-coated ceramic diaphragm is in the range of 65% to 75%; Step 5: preparing a high-efficiency current-collecting negative electrode: cutting the metal lithium strip into a specified size, and welding the nickel strip and the metal lithium by ultrasonic welding to obtain a negative electrode sheet; Step 6: Battery assembly: Assemble the porous fluorinated carbon electrode, negative electrode sheet, and high-porosity carbon-coated ceramic diaphragm obtained in steps 3, 4, and 5, encapsulate them in a battery housing, and seal the battery cover and housing by laser welding; Step 7: Injection: Inject the electrolyte into the battery using vacuum injection; Step 8: Seal: Seal the liquid injection port with a steel nail.

2. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery according to claim 1, characterized in that: In step 1, the electrode material is one or more of fluorinated graphite, fluorinated carbon, fluorinated carbon nanotubes, fluorinated graphene, fluorinated carbon nanofibers, and nano-fluorinated carbon; the emulsifier is PTFE emulsion; and the modified amino alcohol is any one of 2-aminoisobutanol, 2-dimethylamino-2-methyl-1-propanol, and 2-amino-1-butanol, or a combination thereof.

3. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery according to claim 1, characterized in that: In step 1, the conductive agent is composed of silver nanowires and any one of SP, CNT, and graphene in a mass ratio of (1-1.5):

1.

4. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery according to claim 1, characterized in that: In step 1, the binder is composed of PVDF900 and PVDF5130 in a mass ratio of 1: (1-1.2).

5. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery as claimed in claim 1, characterized in that: The first pore-forming agent is NH4HCO3.

6. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery as claimed in claim 1, characterized in that: In step 1, the rotation speed of the high-speed stirring is 300-500 r / min; the rotation speed of the high-speed dispersion is 5000-6000 r / min; the stirring speed of the reverse rotation of the stirring paddle is 30 r / min, and the time is 30 min.

7. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery as claimed in claim 1, characterized in that: The porous fluorinated carbon electrode in step 3 has a pore size of 0.2-0.5 μm.

8. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery as claimed in claim 1, characterized in that: In step 4, the ceramic diaphragm with high porosity and carbon coating has a thickness of 16-25 μm.

9. A method for suppressing high-temperature gas production in a lithium fluoride carbon battery as claimed in claim 1, characterized in that: In step 6, the carbon-coated layer of the high-porosity carbon-coated ceramic separator completely covers the negative electrode, and the ceramic layer completely covers the positive electrode.

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