Lithium carbon fluoride battery electrolyte, application and lithium carbon fluoride battery

Abstract

The invention discloses a fluorocarbon bond breakage catalyst, a lithium fluoride carbon battery electrolyte and a lithium fluoride carbon battery, and belongs to the field of lithium batteries. The fluorocarbon bond cleavage catalyst only comprises a compound of dimethyl aluminum chloride (C2H6AlCl). The fluorocarbon bond breakage catalyst can catalyze C-F bond breakage, so that a large number of LiF crystal nucleuses are pre-generated in electrolyte near the CFx surface before the battery is discharged, the crystallization and growth processes of LiF crystals in the discharge process of the Li / CFx battery are changed, the LiF crystallization process with huge heat productivity is converted into the LiF crystal growth process with small heat productivity, and the LiF / CFx battery has a good heat dissipation effect. And finally, the purpose of reducing heat produced in the battery discharging process is achieved.

Description

Technical Field

[0001] This application relates to a carbon-fluorine bond breaking catalyst, a lithium fluoride carbon battery electrolyte, and a lithium fluoride carbon battery, belonging to the field of lithium batteries. Background Technology

[0002] Lithium / Fluoride (Li / CF) x Li / CF2 batteries are primary batteries with ultra-high energy density and long storage life. These batteries are particularly suitable for emerging applications such as military equipment, interventional medical devices, and aerospace. Current Li / CF2 batteries... x Battery research is at a critical juncture, transitioning from small-scale to large-scale applications. This is hindering Li / CF... x The biggest obstacle to the large-scale application of batteries is the problem of abnormal heat generation during battery discharge. Summary of the Invention

[0003] To solve Li / CF x To address the problem of abnormal heat generation in batteries, this application proposes a carbon-fluorine bond breaking catalyst, a lithium fluoride carbon battery electrolyte, and a lithium fluoride carbon battery. The carbon-fluorine bond breaking catalyst can catalyze the breaking of carbon-fluorine bonds, thereby reducing the heat generated at the positive electrode of the battery. x A large number of LiF crystal nuclei are pre-formed nearby. During battery discharge, fluoride ions and lithium ions preferentially grow on the surface of existing LiF crystal nuclei, reducing the heat release from the formation of new LiF crystal nuclei. Theoretical calculations show that the heat release during LiF crystal nucleation is much greater than that during LiF crystal growth. Therefore, the carbon-fluorine bond breaking catalyst can effectively reduce heat generation during battery discharge, thus achieving the goal of reducing heat generation during battery discharge. According to theoretical calculations, dimethylaluminum chloride is an effective carbon-fluorine bond breaking catalyst, which can effectively reduce CF2+. x It reduces the dissociation energy of F ions on the surface and significantly decreases the formation energy of LiF after the dissociation of F ions, thus playing a role in catalyzing the dissociation of F ions and the formation of LiF.

[0004] According to theoretical calculations, the carbon-fluorine bond cleaving catalyst includes only one compound: dimethylaluminum chloride (C2H6AlCl). According to another aspect of this application, a lithium fluorinated carbon battery electrolyte is provided, comprising a lithium salt, an ester solvent, an ether solvent, and a carbon-fluorine bond cleaving catalyst.

[0005] The carbon-fluorine bond breaking catalyst is selected from the above-mentioned carbon-fluorine bond breaking catalysts.

[0006] Optionally, the lithium salt is selected from at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxalate borate, lithium difluorooxalate borate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium hexafluoroarsenate.

[0007] Optionally, the ester solvent is selected from at least one of dimethyl carbonate, propylene carbonate, ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate.

[0008] Optionally, the ether solvent is selected from at least one of ethylene glycol dimethyl ether, tetrahydrofuran, 1,2-dimethoxyethylene, 1,4-dioxocyclohexane, diethylene glycol dimethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0009] Optionally, the mass of dimethylaluminum chloride accounts for 0.01 to 10% of the total mass of the lithium fluoride carbon battery electrolyte.

[0010] Optionally, the value of dimethylaluminum chloride as a percentage of the total mass of the lithium fluoride carbon battery electrolyte is independently selected from any value among 0.01%, 0.05%, 0.1%, 1%, 2.5%, 5%, 7.5%, 10%, or a range between any two of the above.

[0011] Preferably, the mass of dimethylaluminum chloride accounts for 0.05-5% of the total mass of the lithium fluoride carbon battery electrolyte. More preferably, it is 0.1-2.5%.

[0012] Optionally, the molar concentration of the lithium salt in the lithium fluoride carbon battery electrolyte is 0.01 to 10 M.

[0013] Optionally, the molar concentration of the lithium salt in the lithium fluoride carbon battery electrolyte is independently selected from any value among 0.01M, 0.05M, 0.1M, 0.5M, 1M, 3M, 5M, 8M, 10M or a range between any two of the above.

[0014] Preferably, the molar concentration of lithium salt in the lithium fluoride carbon battery electrolyte is 0.05–5 M, more preferably 0.1–3 M.

[0015] Optionally, the volume ratio of the ester solvent to the ether solvent is 0.01 to 100:1.

[0016] Optionally, the volume ratio of the ester solvent to the ether solvent is independently selected from any ratio of 0.01:1, 0.05:1, 0.1:1, 1:1, 2:1, 10:1, 20:1, 40:1, 50:1, 60:1, 80:1, 100:1 or a range between any two of the above ratios.

[0017] Preferably, the volume ratio of the ester solvent to the ether solvent is 0.05 to 50:1, more preferably 0.1 to 10:1.

[0018] According to another aspect of this application, an application of a lithium fluorinated carbon battery electrolyte in a lithium fluorinated carbon battery is provided.

[0019] Optionally, the operating temperature of the lithium fluoride carbon battery is -40 to 150°C.

[0020] Optionally, the operating temperature of the lithium fluorocarbon battery is independently selected from any value of -40℃, -30℃, -20℃, -10℃, 0℃, 10℃, 20℃, 30℃, 50℃, 70℃, 90℃, 110℃, 130℃, 150℃ or a range between any two of the above.

[0021] Optionally, the allowable discharge rate of the lithium fluoride carbon battery during operation is 0.01C to 10C.

[0022] Optionally, the allowable discharge rate during operation of the lithium fluoride carbon battery is independently selected from any value among 0.01C, 0.05C, 0.1C, 0.5C, 1C, 3C, 5C, 8C, and 10C, or a range between any two of the above.

[0023] According to another aspect of this application, a lithium fluorinated carbon battery is provided, the lithium fluorinated carbon battery comprising a positive electrode, a negative electrode, a separator and an electrolyte;

[0024] The electrolyte is selected from the lithium fluoride carbon battery electrolyte mentioned above.

[0025] Optionally, the operating temperature of the lithium fluoride carbon battery is -40 to 150°C.

[0026] Optionally, the operating temperature of the lithium fluorocarbon battery is independently selected from any value of -40℃, -30℃, -20℃, -10℃, 0℃, 10℃, 20℃, 30℃, 50℃, 70℃, 90℃, 110℃, 130℃, 150℃ or a range between any two of the above.

[0027] Optionally, the allowable discharge rate of the lithium fluoride carbon battery during operation is 0.01C to 10C.

[0028] Optionally, the allowable discharge rate during operation of the lithium fluoride carbon battery is independently selected from any value among 0.01C, 0.05C, 0.1C, 0.5C, 1C, 3C, 5C, 8C, and 10C, or a range between any two of the above.

[0029] The beneficial effects that this application can produce include:

[0030] The carbon-fluorine bond breaking catalyst provided in this application can effectively catalyze the breaking of fluoride ions on the CFx surface and generate a large number of LiF crystal nuclei with lithium salt in the solvent. This changes the crystallization and growth process of LiF crystals during discharge, reducing the large amount of heat that should be released during the original LiF crystal nuclei generation process during discharge, without affecting the normal discharge of the battery, and ultimately achieving the goal of reducing the heat generation of the battery. Detailed Implementation

[0031] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0032] Unless otherwise specified, the raw materials and reagents used in the embodiments of this application were all purchased commercially.

[0033] The analysis method in the embodiments of this application is as follows:

[0034] Electrochemical tests were performed on the assembled flow supercapacitor using a Landian constant current charge-discharge instrument. The equipment used was the CT2001A battery testing system, manufactured by Wuhan Landian Electronics Co., Ltd.

[0035] The assembly process for lithium fluoride carbon batteries is as follows: Fluorocarbon material (Xiamen Zhong Ke Xi Fu) (C / F molar ratio of 1.0), conductive carbon black, and PVDF (polyvinylidene fluoride) are dissolved in N-methylpyrrolidone at a mass ratio of 8:1:1 and mixed evenly. This mixture is then coated onto aluminum foil using a wet film preparation device to form an electrode film with a thickness of 0.15 mm. After vacuum drying, the film is cut into circular electrode sheets with a diameter of 14 mm using a slicing machine. The weight of the active material is then calculated. The fluoride carbon material is used as the positive electrode, with an areal density of 2–50 mg / cm³. 2 The optimal concentration is 5–30 mg / cm³. 2 The 10 mg / cm³ used in the embodiments and comparative examples of this invention 2 Simultaneously, using lithium foil as the negative electrode and Celgard 2500 as the separator, the above materials were assembled according to the positive electrode, separator, and negative electrode configuration. 70 μL of electrolyte was added, and the cells were assembled into CR2016 button batteries in an argon-filled glove box. After the batteries were left to stand at room temperature for 12 hours, a constant current discharge test was performed using a specific current, ranging from 0.005 A / g (weight of fluorinated carbon) to 5 A / g (weight of fluorinated carbon); preferably, it was 0.01 A / g (weight of fluorinated carbon) to 2.5 A / g (weight of fluorinated carbon). In the embodiments and comparative examples of this invention, a discharge current of 1 A / g (weight of fluorinated carbon) was used until a voltage cutoff of 1.5 V was reached. The surface temperature of the assembled button cell was monitored in an adiabatic environment using an adiabatic calorimeter (ARC) (manufacturer: THTBattery Co., Ltd.). The specific monitoring method was as follows: a temperature sensor was attached to the center of the positive electrode of the button cell to sense changes in battery temperature. During the test, the battery discharge capacity and the surface temperature of the positive electrode of the battery at the moment of discharge were recorded.

[0036] Example 1

[0037] Dimethyl carbonate, propylene carbonate, and ethylene glycol dimethyl ether were mixed evenly in a volume ratio of 1:1:1. 1 L of the mixed solvent was weighed, and 1 mol of LiClO4 was added and stirred to dissolve. Then, dimethyl aluminum chloride was added to the mixture at 2.5% of the total mass of the final lithium fluoride carbon battery electrolyte (i.e., the mass of dimethyl aluminum chloride accounts for the total mass of the lithium fluoride carbon battery electrolyte, the same below), and the mixture was stirred and dissolved to obtain the lithium fluoride carbon battery electrolyte.

[0038] Lithium fluoride carbon coin cells were prepared using the aforementioned lithium fluoride carbon battery electrolyte, and electrochemical and temperature tests were performed on the cells. The assembled coin cells had a discharge time of 11 hours and 22 minutes, a discharge capacity of 756 mAh / g based on the mass of the positive electrode active material, and a positive electrode casing temperature of 50.5℃.

[0039] Example 2

[0040] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminum chloride added is changed to 10% (the mass of dimethylaluminum chloride accounts for the total mass of the lithium fluoride carbon battery electrolyte), to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell battery discharged for 10 hours and 42 minutes, and the discharge capacity, calculated based on the mass of the positive electrode active material, was 712 mAh / g, with a positive electrode casing temperature of 52.6°C.

[0041] Example 3

[0042] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminate chloride added is changed to 1%, to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell battery discharged for 11 hours and 9 minutes, and the discharge capacity, calculated based on the mass of the positive electrode active material, was 742 mAh / g. The battery positive electrode casing temperature was 51.1°C.

[0043] Example 4

[0044] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminate chloride added is changed to 0.01%, thus preparing the lithium fluoride carbon battery electrolyte. The assembled coin cell had a discharge time of 11 hours and 6 minutes, and based on the mass of the positive electrode active material, the discharge capacity was 739 mAh / g, and the battery positive electrode casing temperature was 62.1℃.

[0045] Example 5

[0046] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminate chloride added is changed to 5%, to prepare the lithium fluoride carbon battery electrolyte. The assembled button battery discharged for 11 hours and 9 minutes, and the discharge capacity, calculated based on the mass of the positive electrode active material, was 741 mAh / g. The battery positive electrode casing temperature was 62.8°C.

[0047] Example 6

[0048] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminate chloride added is changed to 7.5%, to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell battery discharged for 11 hours and 00 minutes, and the discharge capacity, calculated based on the mass of the positive electrode active material, was 732 mAh / g. The battery positive electrode casing temperature was 62.8°C.

[0049] Comparative Example 1

[0050] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference being that dimethylaluminum chloride was not added, a lithium fluoride carbon battery electrolyte was prepared. The assembled coin cell had a discharge time of 10 hours and 12 minutes, and based on the mass of the positive electrode active material, the discharge capacity was 677 mAh / g, and the battery positive electrode casing temperature was 80.1°C.

[0051] Comparative Example 2

[0052] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that the amount of dimethylaluminate chloride added is changed to 70%, resulting in a lithium fluoride carbon battery electrolyte. The assembled coin cell battery discharged for 9 hours and 37 minutes, and based on the mass of the positive electrode active material, the discharge capacity was 642 mAh / g, with a positive electrode casing temperature of 82.1°C.

[0053] Comparative Example 3

[0054] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that dimethylaluminum chloride is replaced with dimethylaluminum fluoride to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell has a discharge time of 9 hours and 1 minute, and the discharge capacity is 599 mAh / g based on the mass of the positive electrode active material. The battery positive electrode casing temperature is 81.9°C.

[0055] Comparative Example 4

[0056] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that dimethylaluminum chloride is replaced with diethylaluminum chloride to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell battery had a discharge time of 9 hours and 7 minutes, a discharge capacity of 607 mAh / g based on the mass of the positive electrode active material, and a positive electrode casing temperature of 83.9°C.

[0057] Comparative Example 5

[0058] Following the requirements of Example 1, without changing other conditions (the process and conditions are the same as in Example 1), the difference is that dimethylaluminum chloride is replaced with lithium fluoride to prepare the lithium fluoride carbon battery electrolyte. The assembled coin cell had a discharge time of 8 hours and 18 minutes, a discharge capacity of 551 mAh / g, and a positive electrode casing temperature of 77.3°C.

[0059] As shown in Comparative Examples 1-4, dimethylaluminum chloride possesses a unique electronic configuration, making it the only substance, based on quantum chemical calculations, capable of catalyzing the breaking of the CF bond. Without this catalyst, or by adding other substances with similar molecular structures but different electronic configurations, it cannot catalyze the breaking of the CF bond, thus preventing the CF bond from breaking in the battery. x The pre-generation of a large number of LiF crystal nuclei near the surface cannot reduce the heat generated during battery discharge.

[0060] As shown in Comparative Example 5, adding an appropriate amount of lithium fluoride to the electrolyte can achieve a similar effect to adding dimethyl aluminum chloride in pre-nucleating lithium fluoride. However, the added lithium fluoride can only be free in the negative electrode electrolyte, and the particle size of this commercial lithium fluoride is much larger than that of the lithium fluoride generated in situ in Example 1, which leads to a significant increase in the battery's internal resistance, further resulting in a decrease in battery capacity, and has a very limited effect on improving the battery's heating process.

[0061] The carbon-fluorine bond breaking catalyst of the present invention can catalyze the breaking of the CF bond, so that the CF bond is broken before the battery discharges. x A large number of LiF crystal nuclei are pre-generated in the electrolyte near the surface, altering the Li / CF ratio. x The crystallization and growth process of LiF crystals during battery discharge transforms the heat-generating LiF crystallization process into a heat-generating LiF crystal growth process, ultimately reducing the heat generated during battery discharge.

[0062] Unless otherwise specified, all figures appearing in this application specification and claims, such as temperature and time values, should not be construed as absolutely precise values. Due to the standard deviation of measurement techniques, the measured values ​​inevitably contain a certain degree of experimental error.

[0063] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A lithium fluoride carbon battery electrolyte, wherein the lithium fluoride carbon battery electrolyte comprises lithium salt, ester solvent, and ether solvent, characterized in that: It also contains a carbon-fluorine bond cleaving catalyst, which is dimethylaluminum chloride (C2H6AlCl).

2. The electrolyte according to claim 1, characterized in that: The mass of dimethylaluminum chloride accounts for 0.01 to 10% of the total mass of the lithium fluoride carbon battery electrolyte, preferably 0.05 to 5%, and more preferably 0.1 to 2.5%.

3. The electrolyte according to claim 1 or 2, characterized in that: The lithium salt is selected from one or more of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium dioxaborate, lithium difluorooxaborate, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, lithium perchlorate, and lithium hexafluoroarsenate. The molar concentration of the lithium salt in the lithium fluoride carbon battery electrolyte is 0.01–10 M, preferably 0.05–5 M, and more preferably 0.1–3 M.

4. The electrolyte according to claim 1 or 2, characterized in that: The ester solvent is selected from at least one of dimethyl carbonate, propylene carbonate, ethylene carbonate, diethyl carbonate, and methyl ethyl carbonate; The ether solvent is selected from at least one of ethylene glycol dimethyl ether, tetrahydrofuran, 1,2-dimethoxyethylene, 1,4-dioxane, diethylene glycol dimethyl ether, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether. The volume ratio of the ester solvent to the ether solvent is 0.01 to 100:1, preferably 0.05 to 50:1, and more preferably 0.1 to 10:

1.

5. The application of the lithium fluorinated carbon battery electrolyte according to any one of claims 1-4 in a lithium fluorinated carbon battery.

6. The application according to claim 5, characterized in that: The operating temperature of the lithium fluoride carbon battery is -40 to 150°C. The allowable discharge rate of the lithium fluoride carbon battery during operation is 0.01C to 10C.

7. A lithium fluoride carbon battery, the lithium fluoride carbon battery comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that: The electrolyte is selected from any of the lithium fluoride carbon battery electrolytes described in claims 1-4.

8. The lithium fluoride carbon battery according to claim 7, characterized in that: The operating temperature of the lithium fluoride carbon battery is -40 to 150°C. The allowable discharge rate of the lithium fluoride carbon battery during operation is 0.01C to 10C.