A kind of lithium metal II carbon fluoride battery anti-corrosion electrolyte and its application

Abstract

The invention discloses a lithium metal||carbon fluoride battery anti-corrosion electrolyte and application thereof, which contains lithium salt, solvent and additive, the structural formula of the additive is: Compared with the electrolyte without adding additive, the lithium metal||carbon fluoride battery anti-corrosion electrolyte of the invention can construct an oxygen-containing protective layer on the surface of the positive and negative electrodes and other metal parts of the battery, thereby inhibiting the corrosion caused by the electrolyte to them and the galvanic corrosion between metals.

Description

Technical Field

[0001] The invention belongs to the technical field of batteries, and in particular relates to an anti-corrosion electrolyte for lithium metal II carbon fluoride batteries. Background Art

[0002] Lithium metal is the metal with the lowest density, with a density of only 0.534 g cm -2 , and is the metal with the lowest hydrogen standard potential (-3.04V). In the exploration of the limit of battery energy density, lithium metal electrodes are widely used due to their high capacity of 3860mAh g -1 The theoretical specific capacity of lithium metal II carbon fluoride primary battery has become the "holy grail" in the field of lithium batteries. The lithium metal II carbon fluoride primary battery uses carbon fluoride as the anode and lithium metal as the cathode. The main discharge products are lithium fluoride and carbon. Lithium metal II carbon fluoride battery is a solid positive electrode primary battery with extremely high theoretical energy density (when the fluorine-carbon ratio is 1, the theoretical specific capacity is as high as 865mAh g -1 , energy density is as high as 2100Wh kg -1 ) is widely used in precision medicine, aerospace, national defense and military industry, high-end civilian and other fields.

[0003] The storage of lithium metal II carbon fluoride batteries is one of the most important issues in practical applications. The tolerance to extreme storage temperature and humidity and the maximum storage time determine its value as a backup power source. However, since the electrolyte is the most active substance in the battery, it can easily undergo irreversible chemical reactions with lithium metal and carbon fluoride. In addition, the electrolyte and the equally highly reactive lithium metal will also act as media for each other, causing them to corrode other metal parts, such as chemical corrosion and galvanic corrosion. Summary of the invention

[0004] The present invention aims to overcome the defects of the prior art and provide a corrosion-resistant electrolyte for lithium metal II carbon fluoride batteries.

[0005] Another object of the present invention is to provide a lithium metal II carbon fluoride battery based on the above-mentioned lithium metal II carbon fluoride battery anti-corrosion electrolyte.

[0006] The technical solution of the present invention is as follows:

[0007] A lithium metal II carbon fluoride battery anti-corrosion electrolyte, comprising a lithium salt, a solvent and an additive, wherein the additive has a structural formula of

[0008] above Represents the binding site with neighboring atoms.

[0009] In a preferred embodiment of the present invention, the additive is selected from at least one of the following:

[0010]

[0011] In a preferred embodiment of the present invention, the lithium salt is at least one of lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), lithium perchlorate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorophosphate.

[0012] In a preferred embodiment of the present invention, the solvent is at least one of an ester solvent, an ether solvent, N,N-dimethylformamide, sulfolane, acetonitrile, N-methylpyrrolidone and dimethyl sulfoxide.

[0013] More preferably, the ester solvent is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, methyl butyrate and γ-butyrolactone.

[0014] More preferably, the ether solvent is at least one of ethylene glycol dimethyl ether, tetrahydrofuran, dibutyl ether and dimethyl ether.

[0015] Another technical solution of the present invention is as follows:

[0016] A lithium metal II carbon fluoride battery comprises the above-mentioned lithium metal II carbon fluoride battery anti-corrosion electrolyte, a carbon fluoride cathode, a lithium metal anode, a separator, a current collector, a spring, a gasket and a positive and negative electrode shell.

[0017] In a preferred embodiment of the present invention, the material of the fluorinated carbon cathode includes at least one of fluorinated graphite, fluorinated coke, fluorinated graphene, fluorinated carbon nanotubes, fluorinated carbon black, fluorinated diamond and fluorinated carbon fiber, and the fluorine-carbon atomic ratio is 0.1-1.5;

[0018] The material of the lithium metal anode includes at least one of alloy lithium metal, pure metallic lithium, and structurally modified metallic lithium;

[0019] The material of the isolation membrane includes at least one of polyethylene, polypropylene, cellulose and PET non-woven fabric;

[0020] The material of the current collector includes at least one of aluminum, copper, nickel, stainless steel, conductive resin, carbon-coated aluminum foil, and titanium-nickel shape memory alloy.

[0021] Further preferably, the alloy-based lithium-containing metal is selected from lithium-aluminum alloy, lithium-indium alloy, lithium-sulfur alloy, lithium-boron alloy, lithium-manganese alloy, lithium-magnesium alloy and lithium-nickel alloy.

[0022] In a preferred embodiment of the present invention, it is a button cell, a cylindrical cell or a soft pack cell.

[0023] The beneficial effects of the present invention are:

[0024] 1. Compared with the electrolyte without additives, the anti-corrosion electrolyte of the lithium metal II carbon fluoride battery of the present invention can construct an oxygen-containing protective layer on the surface of the positive and negative electrodes and other metal parts of the battery, thereby inhibiting the corrosion caused by the electrolyte and the galvanic corrosion between metals.

[0025] 2. The additive in the present invention has simple ingredients, is harmless to the environment, has low cost, is easy to use, and is suitable for large-scale application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The corrosion current curves at an applied voltage of 0V obtained by testing the lithium metal II copper foil button cells assembled in Example 14, Example 17 and Comparative Example 2 using the zero resistance ammetry (ZRA) method.

[0027] Figure 2 The lithium metal II carbon fluoride batteries assembled according to Example 14, Example 17 and Comparative Example 2 of the present invention were placed in a 60° C. environment and monitored for real-time voltage change curves. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0029] Example 1

[0030] a) Preparation of electrolyte: In an argon-filled glove box (water and oxygen contents are both less than 0.1 ppm), ethylene carbonate and diethyl carbonate are prepared into a mixed solvent in a mass ratio of 3:7, the lithium salt is lithium hexafluorophosphate with a concentration of 1.0 M, and then 5% by mass of additive I-1 is added.

[0031] b) Preparation and testing of lithium metal II copper foil battery: The prepared electrolyte was assembled with the copper foil positive electrode, lithium metal negative electrode, and isolation membrane, and then the corrosion current density was tested by it curve using an electrochemical workstation, and the applied voltage was set to 0V.

[0032] c) Preparation and testing of lithium metal II carbon fluoride battery: The prepared electrolyte was assembled with carbon fluoride positive electrode, lithium metal negative electrode and isolation membrane, and then the electrochemical test channel was set to standby operation, the temperature was set to 60°C, and the setting time was 300h.

[0033] Except for the electrolyte formula, the other implementation steps of Examples 2 to 14 are the same as those of Example 1, as shown in Table 1. Except for the electrolyte formula, the other implementation steps of Comparative Examples 1 and 2 are the same as those of Example 1, as shown in Table 1. The effects of Example 14, Example 17 and Comparative Example 2 are compared. Figure 1 and Figure 2 . Figure 1 The corrosion current curve of the lithium II copper battery obtained by the ZRA method. The stable corrosion current density of Example 14 after 20 hours is only 0.42 μA cm -2 , Example 17 is 0.50μAcm -2 , which is much lower than 0.75 μA cm in Comparative Example 2. -2 . Figure 2 The graph is a relationship between storage time and open circuit voltage of lithium metal II carbon fluoride battery. Compared with comparative example 2, the open circuit voltage of Examples 14 and 17 hardly decays after 300 hours of storage. The above results show that compared with comparative example 2, only a small amount of anti-corrosion electrolyte additive is added to Examples 14 and 17, which significantly improves the anti-corrosion ability of the battery.

[0034] Table 1

[0035]

[0036]

[0037]

[0038] The structural formula of the specific additive is as follows:

[0039]

[0040] From left to right, in order: I-10, I-2, I-3, I-4, I-5, I-6, I-7, I-8, I-9, I-10, I-11, I-12, I-13 and I-14;

[0041] The above description is only a preferred embodiment of the present invention, and therefore cannot be used to limit the scope of the present invention. That is, equivalent changes and modifications made according to the patent scope of the present invention and the contents of the specification should still fall within the scope of the present invention.

Claims

1. A lithium metal / carbon fluoride battery anti-corrosion electrolyte, characterized in that: It contains lithium salt, solvent and additives. The additive is selected from at least one of the following: The additive is added in an amount of 5 wt%; The lithium salt is at least one of lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate, lithium bis(oxalatoborate), lithium difluorooxalatoborate, lithium hexafluoroarsenate, lithium bis(trifluoromethylsulfonyl)imide, lithium bis(fluorosulfonyl)imide and lithium difluorophosphate; The solvent is at least one of an ester solvent, an ether solvent, N,N-dimethylformamide, cyclopentane sulfone, acetonitrile, N-methylpyrrolidone and dimethyl sulfoxide; the ester solvent is at least one of dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, ethylene carbonate, propylene carbonate, methyl butyrate and γ-butyrolactone; the ether solvent is at least one of ethylene glycol dimethyl ether, tetrahydrofuran, dibutyl ether and dimethyl ether.

2. A lithium metal / carbon fluoride battery, characterized in that: The invention comprises the lithium metal|carbon fluoride battery corrosion-resistant electrolyte as claimed in claim 1, a carbon fluoride cathode, a lithium metal anode, a separator, a current collector, a spring, a gasket and a positive and negative electrode shell.

3. A lithium metal / carbon fluoride battery as claimed in claim 2, characterized in that: The material of the fluorinated carbon cathode includes at least one of fluorinated graphite, fluorinated coke, fluorinated graphene, fluorinated carbon nanotubes, fluorinated carbon black, fluorinated diamond and fluorinated carbon fiber, and the fluorine-carbon atomic ratio is 0.1-1.5; The material of the lithium metal anode includes at least one of alloy lithium metal, pure metallic lithium, and structurally modified metallic lithium; The material of the isolation membrane includes at least one of polyethylene, polypropylene, cellulose and PET non-woven fabric; The material of the current collector includes at least one of aluminum, copper, nickel, stainless steel, conductive resin, carbon-coated aluminum foil, and titanium-nickel shape memory alloy.

4. A lithium metal / carbon fluoride battery as claimed in claim 3, characterized in that: The alloy containing lithium metal is selected from lithium aluminum alloy, lithium indium alloy, lithium sulfur alloy, lithium boron alloy, lithium manganese alloy, lithium magnesium alloy and lithium nickel alloy.

5. A lithium metal / carbon fluoride battery according to any one of claims 2 to 4, characterized in that: It is a button cell, cylindrical cell or soft pack cell.

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