A lithium carbon dioxide battery and a method for preparing its positive electrode.

Abstract

This invention discloses a lithium-carbon dioxide battery cathode, a lithium-carbon dioxide battery, and its preparation method, belonging to the field of battery technology. The invention utilizes the reaction of amino acids with inorganic acids to prepare amino acid salt ionic liquids. These amino acid salt ionic liquids are then used to pretreat sawdust, followed by carbonization to prepare activated carbon fibers. Finally, the prepared activated carbon fibers are used as the cathode catalyst to prepare the lithium-carbon dioxide battery cathode. The activated carbon fibers prepared by this method exhibit high peak current, large discharge capacity, and good cycle stability. The ionic liquid C8mimBF4 is used as both the CO2 capture and storage medium and the electrolyte, improving battery life and effectively ensuring battery safety and environmental friendliness. This invention employs multi-cell packs and semi-dry electrode processes to construct a manufacturing process for lithium-carbon dioxide batteries. The resulting batteries exhibit high energy density and good operational stability, demonstrating excellent economic prospects and practical value.

Description

Technical Field

[0001] This invention relates to a high-capacity, fully enclosed lithium carbon dioxide battery cathode, a lithium carbon dioxide battery, and a method for preparing the same, belonging to the field of battery technology. Background Technology

[0002] Research on lithium-carbon dioxide batteries is still in its early stages, with most reported assembled lithium-carbon dioxide batteries being button cells with capacities ranging from 40mAh to 150mAh. Existing lithium-carbon dioxide battery technology suffers from drawbacks such as high manufacturing costs, poor safety performance, and low discharge capacity. Furthermore, it can only be used in a pure CO2 atmosphere and cannot be used in ordinary environments, severely hindering the promotion and development of lithium-carbon dioxide batteries. Summary of the Invention

[0003] To address the problems of low discharge capacity and the fact that existing lithium carbon dioxide batteries can only be used in a pure CO2 atmosphere, this invention provides a high-capacity, fully enclosed lithium carbon dioxide battery.

[0004] To achieve the above objectives, the present invention first provides a method for preparing a lithium carbon dioxide battery cathode, comprising the following steps:

[0005] (1) Preparation of ionic liquid: Mix amino acids, inorganic acids and deionized water to prepare an aqueous solution of amino acid salt ionic liquid;

[0006] (2) Wood pretreatment: The wood is crushed to obtain wood chips. The wood chips are mixed with the amino acid salt ionic liquid aqueous solution obtained in step (1) and placed in a reaction at 100-120℃ and 0.01-0.05Mpa for 2 hours. After the temperature drops to room temperature, the wood chips are taken out and the pretreated wood chips are separated. The pretreated wood chips are washed with deionized water and placed in an oven to dry, so as to obtain pretreated dry wood chips.

[0007] (3) Carbonization treatment: The pretreated dry wood chips obtained in step (2) are placed in a muffle furnace and carbonized under an inert atmosphere to obtain activated carbon fibers.

[0008] (4) Preparation of lithium carbon dioxide battery positive electrode: The activated carbon fiber obtained in step (3) is mixed with conductive agent, binder and organic solvent, ultrasonically dispersed to obtain positive electrode slurry, and the positive electrode slurry is coated on carbon paper current collector and dried to obtain lithium carbon dioxide battery positive electrode.

[0009] In one embodiment of the present invention, the mass ratio of the amino acid to the inorganic acid is 1:1 to 1:3.

[0010] In one embodiment of the present invention, the amino acid includes at least one of cysteine, glycine, and tyrosine, and the inorganic salt includes at least one of nitric acid, hydrochloric acid, and sulfuric acid.

[0011] In one embodiment of the present invention, the mass fraction of the amino acid salt ionic liquid in the aqueous solution of the amino acid salt ionic liquid is 50-75%.

[0012] In one embodiment of the present invention, in step (2), the mass ratio of the wood chips to the amino acid salt ionic liquid is 1:20 to 1:25.

[0013] In one embodiment of the present invention, in step (3), the heating rate of the muffle furnace is 15-20°C / min, and the carbonization treatment is carried out at a temperature of 500-700°C for 30-50 minutes.

[0014] In one embodiment of the present invention, in step (4), the conductive agent includes at least one of acetylene black, graphene, and carbon nanotubes; the binder includes at least one of polytetrafluoroethylene emulsion, styrene-butadiene rubber emulsion, and carboxymethyl cellulose; and the organic solvent includes at least one of ethanol, acetone, and carbonate.

[0015] In one embodiment of the present invention, in step (4), the mass ratio of the activated carbon fiber, conductive agent, and binder is 8:1.5:0.5.

[0016] In one embodiment of the present invention, in step (4), the ultrasonic power during ultrasonic dispersion is 250-300W and the ultrasonic time is 20-30min.

[0017] In one embodiment of the present invention, in step (4), the positive electrode slurry is coated by a coating machine, and a positive electrode material with a thickness of 300 μm is formed by extrusion onto a carbon paper current collector, and then dried at 150°C for 10 to 20 minutes.

[0018] The present invention also provides a lithium carbon dioxide battery cathode prepared by the above preparation method.

[0019] The present invention also provides an application of the above-mentioned lithium carbon dioxide battery cathode in the field of batteries.

[0020] In one embodiment of the invention, the application includes the preparation of a lithium carbon dioxide battery using a lithium carbon dioxide battery cathode.

[0021] In one embodiment of the present invention, the lithium carbon dioxide battery includes a battery casing, a lithium negative electrode housed within the battery casing, a lithium carbon dioxide positive electrode, an electrolyte, a separator between the positive and negative electrodes, and a carbon dioxide atmosphere.

[0022] In one embodiment of the present invention, the battery casing includes a housing 1, a conductive sheet 2, a support sheet 3, a housing cover 4, a gasket 5, a positive electrode tab 9, and a negative electrode tab 6. The conductive sheet 2, the support sheet 3, the housing cover 4, the gasket 5, the positive electrode tab 9, and the negative electrode tab 6 are detachably fixed to the housing 1 by set screws 7. A cap 8 is provided on the top of the gasket 5. Figure 1 As shown.

[0023] In one embodiment of the present invention, the electrolyte is an ionic liquid electrolyte, which includes 1-octyl-3-methylimidazolium tetrafluoroborate (C8mimBF4).

[0024] In one embodiment of the present invention, the method for preparing the lithium carbon dioxide battery includes the following steps:

[0025] S1. The positive electrode of the lithium carbon dioxide battery is fabricated by welding tabs;

[0026] S2. The positive electrode sheet of the battery obtained in step S1 is wound with a polypropylene separator and a negative lithium sheet to obtain a core package, which is then hot-pressed and connected in parallel to prepare a battery cell.

[0027] S3. The parallel cells and insulating base obtained in step S2 are sequentially connected to the battery casing through flexible connection welding and ultrasonic welding, and then the casing is sealed by vacuum baking.

[0028] S4. Inject the ionic liquid electrolyte into the battery, and then introduce carbon dioxide through the cap on the battery casing to obtain a lithium carbon dioxide battery.

[0029] In one embodiment of the present invention, the core package (JR) is formed by winding positive and negative electrode sheets with a length of 171cm and a width of 12.3cm, and the theoretical capacity can reach 15Ah.

[0030] In one embodiment of the present invention, the battery casing is an explosion-proof aluminum casing with an openable cap for replenishing CO2. After entering the casing through the cap, CO2 is captured and stored by the ionic liquid electrolyte for battery operation. When CO2 is insufficient, it can be replenished again.

[0031] The beneficial effects of this invention are:

[0032] (1) This invention uses a mixture of amino acids and inorganic salts to prepare an amino acid salt ionic liquid. This ionic liquid is then used to pretreat sawdust and carbonize it to obtain activated carbon fibers. The prepared activated carbon fibers are then mixed with a conductive agent and a binder to prepare a lithium carbon dioxide battery cathode material. Compared with traditional carbon materials, the activated carbon fibers prepared in this invention have higher specific capacity, energy density, and excellent electrochemical stability. When used in batteries, they can impart characteristics such as high peak current, large discharge capacity, and good cycle stability.

[0033] (2) The present invention uses ionic liquid C8mimBF4 as electrolyte, which can effectively solve the shortcomings of traditional electrolytes such as easy vaporization at high temperature, high viscosity and poor heat resistance, and salt precipitation at low temperature. While improving battery life, it ensures the environmental protection and safety of the battery.

[0034] (3) The ionic liquid C8mimBF4 used in this invention has the characteristic of high solubility for CO2, and can be used as a medium for capturing and storing CO2 at the same time, realizing the full enclosure of lithium carbon dioxide battery, solving the limitation of traditional open lithium carbon dioxide battery that can only be used in pure CO2 environment, and enabling the battery to be used in ordinary environment.

[0035] (4) This invention constructs a manufacturing process for a large-capacity, standard-sized, fully enclosed lithium carbon dioxide battery, realizing the full enclosure of the lithium carbon dioxide battery and conforming to the standard lithium-ion battery size specifications. It meets the current lithium-ion battery production process requirements and provides an important reference for promoting the early industrialization of lithium carbon dioxide batteries and moving towards high-quality, high-efficiency, and low-cost manufacturing in the future. Attached Figure Description

[0036] Figure 1 This is an exploded view of the lithium carbon dioxide battery of the present invention;

[0037] Figure 2 This is a front view of the lithium carbon dioxide battery of the present invention;

[0038] Figure 3 This is a side view of the lithium carbon dioxide battery of the present invention;

[0039] Figure 4 This is a top view of the lithium carbon dioxide battery of the present invention;

[0040] Figure 5 This is a flowchart illustrating the manufacturing process of the lithium carbon dioxide battery of the present invention.

[0041] Figure 6 This is a constant current charge-discharge test diagram of the activated carbon fiber material in Example 3;

[0042] Figure 7 The image shows the cyclic voltammetry test results of the activated carbon fiber material in Example 4. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] Example 1

[0045] A method for preparing a lithium carbon dioxide battery cathode includes the following steps:

[0046] S1. Take balsa wood and cut it into slices of 1.5cm×1.5cm×0.1cm.

[0047] S2. Take 33.09 mL of 68% concentrated nitric acid, add 15.87 mL of deionized water, stir, and add 60.58 g of cysteine ​​to prepare a 75% cysteine ​​salt ionic liquid aqueous solution. Add the slices obtained in S1 and the prepared cysteine ​​salt ionic liquid aqueous solution to an Erlenmeyer flask at a mass ratio of 1:20 and soak for 48 hours.

[0048] S3. Place the conical flask containing the slices and cysteine ​​salt ionic liquid solution obtained in S2 into an autoclave and react at 105℃ and 0.01-0.05 MPa for two hours. After cooling to room temperature, remove the flask and backwash the slices with deionized water until the waste liquid after washing is free of bubbles. Then wash with anhydrous ethanol two or three times, and finally dry in an oven.

[0049] S4. Place the slices obtained in S3 into a 300ml porcelain crucible, cover it, and place it in a muffle furnace with a furnace temperature below 100℃. Nitrogen gas is continuously introduced into the muffle furnace. The heating rate of the muffle furnace is set to 15℃ / min. When the furnace temperature reaches 500℃, start timing for 30 minutes. After the dwell time is reached, quickly remove the sample and place it outside the furnace to cool to room temperature. After thoroughly mixing the sample, place it in a sealed container and store it in the dark to obtain activated carbon fiber material.

[0050] S5. Mix the activated carbon fiber material obtained in S4, the conductive agent acetylene black, and the binder polytetrafluoroethylene in a mass ratio of 8:1.5:0.5, add anhydrous ethanol, and sonicate for 20 minutes using an ultrasonic disperser to obtain the positive electrode slurry.

[0051] S2. The positive electrode slurry obtained in step S1 is coated using a coating machine and extruded onto a carbon cloth current collector to form an electrode material with a thickness of 300 micrometers. After drying, a lithium carbon dioxide battery positive electrode is prepared.

[0052] Example 2

[0053] A lithium carbon dioxide battery comprises a battery casing, a lithium negative electrode 12 housed within the battery casing, a battery positive electrode 10, an electrolyte, a separator 11 between the positive and negative electrodes, and a carbon dioxide atmosphere. The battery casing includes a housing 1, a conductive sheet 2, a support sheet 3, a housing cover 4, a gasket 5, a positive electrode tab 9, and a negative electrode tab 6. The lithium negative electrode 12 is connected to the negative electrode tab 6 via the conductive sheet 2, and the battery positive electrode 10 is connected to the positive electrode tab 9 via the conductive sheet 2. The support sheet 3 and the gasket 5 are sequentially arranged on the conductive sheet 2. The positive electrode tab 9 and the negative electrode tab 6 are pressed on the upper part of the gasket 5 and fixed to the housing cover 4 by a set screw 7. A cap 8 is installed on the housing cover 4, and carbon dioxide gas is injected into the housing 1 through the cap 8.

[0054] A method for preparing a lithium carbon dioxide battery includes the following steps:

[0055] S1. The positive electrode of the lithium carbon dioxide battery is prepared by welding tabs.

[0056] S2. The positive electrode sheet of the battery obtained in step S1 is wound with a Celgard 2500 polypropylene separator and a negative lithium sheet to obtain a core package (171cm long and 12.3cm wide). After hot pressing, the parallel battery cell is prepared.

[0057] S3. The parallel battery cell and conductive sheet obtained in step S2 are sequentially connected to a standard size (20mm*65mm*138mm) explosion-proof aluminum shell through soft connection welding and ultrasonic welding, and then the shell is sealed by vacuum baking.

[0058] S4. Inject the electrolyte C8mimBF4 into the battery, and then introduce carbon dioxide through the cap on the battery casing to obtain a lithium carbon dioxide battery.

[0059] The preparation method of the lithium carbon dioxide battery cathode is the same as that in Example 1.

[0060] Through reversible reactions To achieve the charging and discharging of the lithium-carbon dioxide battery, CO2 gas injected into the housing 1 through the cap 8 is captured and stored by C8mimBF4. During the discharge process of the lithium-carbon dioxide battery, metallic lithium first loses electrons (electrons). - Oxidized to Li + Then, along with the electrolyte, it is transported to the surface of the positive electrode aluminum and reacts with the obtained e. - Furthermore, the activated CO2 combines and reacts to form Li2CO3 and C. The charging and discharging processes of lithium carbon dioxide are exactly the opposite; it is charged under the influence of an external voltage, and the Li2CO3 and C generated during discharging can be converted into Li2CO3 and C on the aluminum surface of the positive electrode under the influence of an external voltage. + e- CO2, Li + As the electrolyte transfers to the negative electrode, it can capture the electrons that have transferred to the negative electrode along with the external circuitry of the battery. - Lithium metal is generated, and the generated CO2 participates in subsequent battery cycles. CO2 can be replenished when its consumption is insufficient, thus the battery can be used in ordinary environments.

[0061] Example 3

[0062] Figure 6 The figure shows the constant current charge-discharge (GCD) test curve of activated carbon fiber material at room temperature (25°C). The preparation method of activated carbon fiber material is the same as steps S1 to S4 in the examples. The figure shows that at a current density of 0.5 A / g, the specific capacitance of activated carbon fiber is 343.05 F / g, and the energy density is as high as 1876 Wh / kg. In contrast, the specific capacitance of the traditional cathode carbon material Super-p conductive carbon black under the same conditions is 39.28 F / g, and the energy density is 268 Wh / kg, indicating that the specific capacitance of activated carbon fiber material is much larger.

[0063] As can be seen from the above test results of specific capacity and energy density, the lithium carbon dioxide battery prepared using the activated carbon fiber prepared in this invention as the positive electrode catalyst material has a higher energy density, a larger capacity, and better performance. It can be used as an ideal energy storage device to provide sustainable power output for long-distance transportation.

[0064] Example 4

[0065] Figure 7 The figure shows the cyclic voltammetry (CV) curve of the activated carbon fiber material. The preparation method of the activated carbon fiber material is the same as steps S1 to S4 in the examples, and the voltage range during testing is -1 to 0V. This figure shows the double-layer effect of the carbon electrode material; the closer the curve is to a rectangle, the better the effect. When the scan rate is 5mV / s, the CV curve has a large area around the electrode and no other peaks. The oxidation peak and reduction peak are approximately the same, indicating that the prepared electrode has strong capacitance performance, and the material has good electrochemical stability and reversibility in this voltage range. The cathode prepared using the activated carbon fiber of this invention as the cathode catalyst can enable the efficient and reversible formation and decomposition of insulating Li2CO3 in lithium carbon dioxide batteries, effectively improving the discharge capacity and other performance characteristics of lithium carbon dioxide batteries.

[0066] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit this application. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of this application. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in this application should still be covered by the claims of this application.

Claims

1. A method for preparing a lithium carbon dioxide battery cathode, characterized by, Includes the following steps: (1) Preparation of ionic liquid: Mix amino acids, inorganic acids and deionized water to prepare an aqueous solution of amino acid salt ionic liquid; the molar ratio of amino acids to inorganic acids is 1:1 to 1:3, the amino acids include at least one of cysteine, glycine and tyrosine, the inorganic acids include at least one of nitric acid, hydrochloric acid and sulfuric acid, and the mass fraction of amino acid salt ionic liquid in the aqueous solution is 50 to 75%; (2) Wood pretreatment: Wood is crushed to obtain wood chips. The wood chips are mixed with the amino acid salt ionic liquid aqueous solution obtained in step (1) and placed in a reaction at 100~120℃ and 0.01~0.05MPa for 2 hours. After the temperature drops to room temperature, the wood chips are taken out and the pretreated wood chips are separated. The pretreated wood chips are washed with deionized water and dried in an oven to obtain pretreated dry wood chips. The mass ratio of the wood chips to the amino acid salt ionic liquid is 1:20~1:

25. (3) Carbonization treatment: The pretreated dry wood chips obtained in step (2) are placed in a muffle furnace and carbonized under an inert atmosphere to obtain activated carbon fibers. (4) Preparation of lithium carbon dioxide battery positive electrode: The activated carbon fiber obtained in step (3) is mixed with conductive agent, binder and organic solvent, ultrasonically dispersed to obtain positive electrode slurry, and the positive electrode slurry is coated on carbon paper current collector and dried to obtain lithium carbon dioxide battery positive electrode; the mass ratio of activated carbon fiber, conductive agent and binder is 8:1.5:0.5, the ultrasonic power during ultrasonic dispersion is 250~300W and the ultrasonic time is 20~30min.

2. The production method according to claim 1, characterized by, In step (3), the heating rate of the muffle furnace is 15~20℃ / min, and the carbonization treatment is carried out at a temperature of 500~700℃ for 30~50min.

3. The preparation method according to claim 1, characterized in that, In step (4), the conductive agent includes at least one of acetylene black, graphene, and carbon nanotubes; the binder includes at least one of polytetrafluoroethylene emulsion, styrene-butadiene rubber emulsion, and carboxymethyl cellulose; and the organic solvent includes at least one of ethanol, acetone, and carbonate.

4. The lithium carbon dioxide battery cathode prepared by the preparation method according to any one of claims 1 to 3.

5. The application of the lithium carbon dioxide battery cathode as described in claim 4 in the field of batteries.

6. Use according to claim 5, characterized in that, The applications include the fabrication of lithium carbon dioxide batteries using lithium carbon dioxide battery cathodes.

7. Use according to claim 6, characterized in that, The lithium carbon dioxide battery includes a battery casing, a lithium negative electrode housed within the battery casing, a lithium carbon dioxide positive electrode, an electrolyte, a separator between the positive and negative electrodes, and a carbon dioxide atmosphere.

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