High-voltage low-temperature lithium / carbon fluoride battery and electrolyte thereof

Abstract

The invention belongs to the field of primary batteries, and particularly relates to a high-voltage low-temperature lithium / carbon fluoride battery and an electrolyte thereof, and the electrolyte is composed of an additive 4-aminophenylboronic acid pinacol ester, a lithium salt and a solvent. The lithium salt is lithium tetrafluoroborate or lithium hexafluorophosphate. The additive accounts for 0.1-2 wt% of the total mass of the electrolyte, and the concentration of the lithium salt is 0.5-4 mol / L. By adding 4-aminophenylboronic acid pinacol ester into the electrolyte, a battery voltage platform is improved, an ion transmission channel is opened, so that further discharging of the battery is promoted, transmission of Li < + > on an interface is accelerated, lithium fluoride accumulation is avoided, and the components of the electrolyte have the advantages of being low in cost, easy to prepare, safe and free of pollution. The prepared battery has relatively high voltage platform, energy density and power density in a wide temperature range (-60 to 25 DEG C).

Description

Technical Field

[0001] This invention belongs to the field of primary batteries, specifically relating to a high-voltage, low-temperature lithium / carbon fluoride battery and its electrolyte. Background Technology

[0002] Lithium / carbon fluoride batteries, as a primary battery system, hold an irreplaceable position in fields such as implantable medical devices, aerospace, and military electronic equipment due to their ultra-high theoretical energy density (2180 Wh / kg, x=1), stable discharge voltage platform, extremely low self-discharge rate, and excellent safety.

[0003] Despite the significant theoretical advantages of lithium / carbon fluoride batteries, their practical application is constrained by two key issues: First, poor rate performance. Carbon fluoride itself is an electronic insulator, and the LiF generated during discharge is a typical ionic crystal with extremely high electrical insulation. Its irreversible deposition on the surface of the positive electrode particles forms a dense passivation layer, severely hindering electron and ion transport, leading to a sharp drop in capacity at high discharge rates. Second, voltage hysteresis and low energy efficiency. The actual operating voltage of the battery is significantly lower than the thermodynamic equilibrium voltage. This is because the chemical energy of the first electrochemical reaction in the formation of the intermediate phase is mainly converted into electrical energy, while the chemical energy of the second step, the decomposition reaction of the intermediate phase, is mainly converted into heat energy. However, the battery voltage is determined by the first electrochemical reaction.

[0004] To address these performance limitations, various technical solutions have been explored. Traditional methods primarily focus on optimizing the electrolyte system, including using low-viscosity, low-freezing-point organic solvents (such as chain ethers like DME and cyclic ethers like THF) and novel lithium salts (such as LiTFSI and LiFSI) to improve ionic conductivity. Furthermore, various functional additives, including fluorinated solvents (such as FEC) and nitrile compounds (such as SN and ADN), have been explored to form a more stable interfacial film on the electrode surface.

[0005] However, these traditional methods have significant limitations. While they can improve the ionic conductivity or interfacial stability of the electrolyte to some extent, they fail to fundamentally solve the core problem of interfacial passivation of the discharge product LiF. LiF has extremely low solubility in conventional organic electrolytes, and once formed, it continuously accumulates at the reaction interface, becoming a barrier to ion migration. Especially at low temperatures (<-40 °C), the electrolyte viscosity increases, the ion migration rate slows down, and the dissolution of LiF further slows down, leading to a sharp decline in battery performance. Existing technologies cannot effectively overcome this limitation, causing the performance of lithium / carbon fluoride batteries in low-temperature applications to fall far short of theoretical expectations.

[0006] Therefore, developing a novel electrolyte technology capable of dissolving LiF and fundamentally eliminating its interfacial passivation effect has become a key challenge in overcoming the performance bottleneck of lithium / carbon fluoride batteries. An innovative solution is urgently needed that provides an effective dissolution pathway to address the fundamental problem of LiF's low solubility leading to interfacial passivation, thereby significantly improving the battery's low-temperature performance. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-voltage, low-temperature lithium / carbon fluoride battery and its electrolyte. By adding 4-aminophenylboronic acid pinacol ester to the electrolyte, the problems of low LiF solubility leading to interface passivation effect and low voltage plateau of carbon fluoride battery are effectively solved, thereby improving the overall performance of the battery. The prepared battery has a high voltage plateau, energy density and power density at low temperature and room temperature (-60 - 25 ℃).

[0008] The technical solution of this invention to solve the technical problem is as follows: A first aspect of the present invention is to provide a high-pressure, low-temperature lithium / carbon fluoride battery electrolyte, which is composed of additives, lithium salts and solvents.

[0009] Furthermore, the additive used is 4-aminophenylboronic acid pinacol ester. This is because the synergistic effect of the hydrogen bonding effect of the amino group and the electron-deficient effect of boron allows the F in LiF to... - More easily attracted, achieving the effect of dissolving LiF, the para-amino group has a better conjugation effect and steric hindrance than the ortho-amino and meta-amino groups, and is the most effective in the dissolution process of LiF.

[0010] Further, the additive accounts for 0.1-2 wt% of the total mass of the electrolyte (calculated as a mass fraction of (solute mass / total solution mass) × 100%). More preferably, the additive accounts for 0.5 wt% of the total mass of the electrolyte.

[0011] Furthermore, the lithium salt is lithium tetrafluoroborate or lithium hexafluorophosphate.

[0012] Furthermore, the concentration of the lithium salt is 0.5-4 mol / L, and more preferably, the concentration of the lithium salt is 1 mol / L.

[0013] Furthermore, when the lithium salt is lithium tetrafluoroborate, the solvent is propylene carbonate and ethylene glycol dimethyl ether in a volume ratio of 1:1; when the lithium salt is lithium hexafluorophosphate, the solvent is ethylene carbonate and diethyl carbonate in a volume ratio of 1:1.

[0014] Furthermore, the electrolyte preparation method is as follows: first, the solvents are mixed evenly to form a co-solvent; then, lithium salt is added and dissolved to obtain the electrolyte; then, additives are added and dissolved evenly to obtain the electrolyte.

[0015] A second aspect of the present invention provides a high-pressure, low-temperature lithium / fluorinated carbon battery, comprising a positive electrode, a negative electrode, a separator, and the aforementioned high-pressure, low-temperature lithium / fluorinated carbon battery electrolyte.

[0016] Furthermore, the high-pressure low-temperature lithium / carbon fluoride battery electrolyte is composed of 4-aminophenylborate pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether, wherein the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1, the concentration of lithium tetrafluoroborate is 1 mol / L, and the mass percentage of additives is 0.5 wt%.

[0017] Furthermore, the positive electrode is obtained by dispersing fluorinated carbon positive electrode material, conductive carbon black and binder PVDF in N-methylpyrrolidone at a mass ratio of 8-9:0.5-1:0.5-1 (preferably 8:1:1), mixing thoroughly, coating on carbon-coated aluminum foil, and drying.

[0018] Furthermore, the negative electrode is made of lithium sheet or lithium strip with a thickness of 50-500 μm.

[0019] Furthermore, the diaphragm is a PE diaphragm (25 μm thick).

[0020] Furthermore, the fluorinated carbon cathode material is fluorinated carbon or fluorinated graphite.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) Based on commercial electrolytes, this invention screened additives, 4-aminophenylboronic acid pinacol ester, which can dissolve lithium fluoride through hydrogen bonding by anchoring specific groups -NH2, thereby improving the battery voltage plateau, opening ion transport channels, and thus promoting further battery discharge and accelerating Li + During interface transfer, avoid lithium fluoride buildup.

[0022] (2) Based on the battery electrolyte of the present invention, the lithium / carbon fluoride full cell composed of matching lithium metal anode has a high voltage platform, energy density and power density in a wide temperature range (-60 - 25 ℃), which is of great significance for promoting the application of lithium / carbon fluoride batteries in special defense and military fields.

[0023] (3) The electrolyte components provided by the present invention have the advantages of low cost, easy preparation, safety and no pollution, and can be applied on a large scale. Attached Figure Description

[0024] Figure 1 This is a comparison diagram of the lithium-ion desolvation energy barrier for Examples 1, 2, 5 and Comparative Example 1.

[0025] Figure 2This is a SEM image of the electrode surface after discharge in Example 8.

[0026] Figure 3 This is a SEM image of the electrode surface after discharge in Comparative Example 9.

[0027] Figure 4 Impedance diagrams for Examples 9, 12, and 9 at different temperatures are shown.

[0028] Figure 5 The discharge curves of the batteries in Example 8 and Comparative Example 9 at 25 °C are shown.

[0029] Figure 6 The graph shows a comparison of the discharge curves of the batteries in Examples 8-12 and Comparative Example 9 at -50 °C.

[0030] Figure 7 The discharge curves of the batteries in Example 8, Comparative Examples 9-10, and Comparative Examples 13-15 at -50 °C are shown.

[0031] Figure 8 The discharge curves of the batteries in Examples 8-10, Examples 12-13, and Comparative Examples 9 and 15 at -60 °C are shown.

[0032] Figure 9 The discharge curves of the batteries in Example 14 and Comparative Example 16 at 25 °C are shown. Detailed Implementation

[0033] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0034] A first aspect of the present invention is to provide a high-pressure, low-temperature lithium / carbon fluoride battery electrolyte, which comprises additives, lithium salts, and solvents. Preferably, the electrolyte additive is one of the following: 4-aminophenylboronic acid pinacol ester, 3-aminophenylboronic acid pinacol ester, 2-aminophenylboronic acid pinacol ester, phenylboronic acid pinacol ester, 4,4,5,5-tetramethyl-1,3,2-dihexaoxopentane, aniline, and 3-amino-4-fluorophenylboronic acid pinacol ester. More preferably, the additive is 4-aminophenylboronic acid pinacol ester.

[0035] Preferably, the additive accounts for 0.1-2 wt% of the total mass of the electrolyte (calculated as a mass fraction of (solute mass / total solution mass) × 100%). More preferably, the additive accounts for 0.5 wt% of the total mass of the electrolyte.

[0036] Preferably, the lithium salt is lithium tetrafluoroborate or lithium hexafluorophosphate. The lithium salt concentration is 0.5-4 mol / L. More preferably, the lithium salt concentration is 1 mol / L.

[0037] Preferably, when the lithium salt is lithium tetrafluoroborate, the solvent is propylene carbonate and ethylene glycol dimethyl ether in a volume ratio of 1:1; when the lithium salt is lithium hexafluorophosphate, the solvent is ethylene carbonate and diethyl carbonate in a volume ratio of 1:1.

[0038] Preferably, the electrolyte is prepared by: first, uniformly mixing the solvents to form a co-solvent, then adding lithium salt, dissolving it to obtain the electrolyte, and then adding additives, dissolving them uniformly to obtain the electrolyte.

[0039] A second aspect of the present invention provides a high-pressure, low-temperature lithium / carbon fluoride battery, comprising a positive electrode, a negative electrode, a separator, and the electrolyte described above.

[0040] Preferably, the electrolyte is composed of 4-aminophenylborate pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether, wherein the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1, the concentration of lithium tetrafluoroborate is 1 mol / L, and the mass percentage of additives is 0.5 wt%.

[0041] Preferably, the positive electrode is made by dispersing fluorinated carbon positive electrode material, conductive carbon black and binder PVDF in N-methylpyrrolidone at a mass ratio of 8-9:0.5-1:0.5-1 (preferably 8:1:1), mixing thoroughly, coating onto carbon-coated aluminum foil, and drying.

[0042] Preferably, the negative electrode is a lithium sheet or lithium strip with a thickness of 50-500 μm.

[0043] Preferably, the diaphragm is a PE diaphragm (25 μm thick).

[0044] Preferably, the fluorinated carbon cathode material is fluorinated carbon or fluorinated graphite.

[0045] Example 1 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 0.5 wt%.

[0046] The structural formula of pinacol 4-aminophenylboronic acid (CAS Number: 214360-73-3) is as follows: .

[0047] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0048] Comparative Example 1 The electrolyte consists of lithium tetrafluoroborate, propylene carbonate, and ethylene glycol dimethyl ether; the concentration of lithium tetrafluoroborate is 1 mol / L. The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added, and after dissolution, a uniform electrolyte with a lithium tetrafluoroborate concentration of 1 mol / L is obtained.

[0049] Example 2 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 0.1 wt%.

[0050] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.1 wt%.

[0051] Example 3 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 0.2 wt%.

[0052] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.2 wt%.

[0053] Example 4 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 0.8 wt%.

[0054] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.8 wt%.

[0055] Example 5 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 1 wt%.

[0056] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 1 wt%.

[0057] Example 6 The electrolyte is composed of 4-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4-aminophenylboronic acid pinacol ester is 2 wt%.

[0058] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 2 wt%.

[0059] EIS tests were performed on Examples 1, 2, 5 and Comparative Example 1, and their desolvation energy barriers were obtained by fitting.

[0060] Depend on Figure 1 It can be seen that the desolvation energy barrier of the embodiment is lower, desolvation is easier, and the solvation structure is looser than that of Comparative Example 1.

[0061] Comparative Example 2 The electrolyte is composed of 3-aminophenylboronic acid pinacol ester, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of 3-aminophenylboronic acid pinacol ester is 0.5 wt%.

[0062] The structural formula of pinacol ester 3-aminophenylboronic acid (CAS Number: 210907-84-9) .

[0063] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 3-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0064] Comparative Example 3 The electrolyte is composed of pinacol 2-aminophenylborate, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate to ethylene glycol dimethyl ether is 1:1; and the mass percentage of pinacol 2-aminophenylborate is 0.5 wt%.

[0065] The structural formula of pinacol ester 2-aminophenylboronic acid (CAS Number: 99-34-3) is as follows: .

[0066] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 2-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0067] Comparative Example 4 The electrolyte is composed of pinacol phenylborate, lithium tetrafluoroborate, propylene carbonate and dimethyl ethylene glycol ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate to dimethyl ethylene glycol ether is 1:1; and the mass percentage of pinacol phenylborate is 0.5 wt%.

[0068] The structural formula of pinacol phenylboronic acid ester (CAS Number: 24388-23-6) is as follows: .

[0069] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then pinacol phenylboronic acid is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0070] Comparative Example 5 The electrolyte consists of 4,4,5,5-tetramethyl-1,3,2-dihexylborane, lithium tetrafluoroborate, propylene carbonate, and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate to ethylene glycol dimethyl ether is 1:1; and the mass percentage of 4,4,5,5-tetramethyl-1,3,2-dihexylborane is 0.5 wt%.

[0071] The structural formula of 4,4,5,5-tetramethyl-1,3,2-dihexaoxopentane (CAS Number: 25015-63-8) is as follows: .

[0072] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 4,4,5,5-tetramethyl-1,3,2-diaxopentane is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0073] Comparative Example 6 The electrolyte is composed of aniline, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate to ethylene glycol dimethyl ether is 1:1; and the mass percentage of aniline is 0.5 wt%.

[0074] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then aniline is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0075] The structural formula of aniline (CAS Number: 62-53-3) .

[0076] Comparative Example 7 The electrolyte is composed of pinacol 3-amino-4-fluorophenylboronic acid, lithium tetrafluoroborate, propylene carbonate and ethylene glycol dimethyl ether. The concentration of lithium tetrafluoroborate is 1 mol / L; the volume ratio of propylene carbonate and ethylene glycol dimethyl ether is 1:1; and the mass percentage of pinacol 3-amino-4-fluorophenylboronic acid is 0.5 wt%.

[0077] The structural formula of pinacol ester 3-amino-4-fluorophenylboronic acid (CAS Number: 819058-34-9) is as follows: .

[0078] The specific preparation method is as follows: First, propylene carbonate and ethylene glycol dimethyl ether are mixed uniformly at a volume ratio of 1:1 to form a co-solvent; then lithium tetrafluoroborate is added to obtain a uniform solution with a lithium tetrafluoroborate concentration of 1 mol / L; then 3-amino-4-fluorophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0079] Example 7 The electrolyte consists of pinacol 4-aminophenylborate, lithium hexafluorophosphate, ethylene carbonate, and diethyl carbonate; the concentration of lithium hexafluorophosphate is 1 mol / L; and the volume ratio of ethylene carbonate to diethyl carbonate is 1:1.

[0080] The specific preparation method is as follows: First, ethylene carbonate and diethyl carbonate are mixed uniformly in a volume ratio of 1:1 to form a co-solvent; then lithium hexafluorophosphate is added and dissolved to obtain a uniform solution with a lithium hexafluorophosphate concentration of 1 mol / L; then 4-aminophenylboronic acid pinacol ester is added and stirred evenly to obtain an electrolyte with an additive mass fraction of 0.5 wt%.

[0081] Comparative Example 8 The electrolyte consists of lithium hexafluorophosphate, ethylene carbonate, and diethyl carbonate; the concentration of lithium hexafluorophosphate is 1 mol / L; and the volume ratio of ethylene carbonate to diethyl carbonate is 1:1.

[0082] The specific preparation method is as follows: First, ethylene carbonate and diethyl carbonate are mixed uniformly in a volume ratio of 1:1 to form a co-solvent; then lithium hexafluorophosphate is added, and after dissolution, a uniform electrolyte with a lithium hexafluorophosphate concentration of 1 mol / L is obtained.

[0083] Example 8 A high-voltage, low-temperature lithium / carbon fluoride battery includes a positive electrode, a negative electrode, a separator, and an electrolyte. Positive electrode: Fluorocarbon, conductive carbon black (Super P) and PVDF are mixed evenly in a mass ratio of 8:1:1 and dispersed in N-methylpyrrolidone. The mixture is stirred thoroughly for 8 hours until a uniform positive electrode slurry is obtained. The positive electrode slurry is then uniformly coated onto carbon-coated aluminum foil, dried in an 80 °C drying oven for 12 hours, and then cut into positive electrodes with a diameter of 10 mm. Negative electrode: Lithium sheet, 14 mm in diameter and 100 μm thick; Diaphragm: PE diaphragm, SK Innovation Co., Ltd. Electrolyte: The electrolyte of Example 1 was used; Battery assembly: Assemble the button cell in the following order: negative electrode shell - spring contact - gasket - negative electrode - electrolyte - separator - electrolyte - positive electrode - positive electrode shell. The battery specification is 2032.

[0084] After the assembled battery was left to stand for 12 hours, it was discharged at room temperature with a cutoff voltage of 1.5 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0085] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material. After the discharge was completed, the battery was disassembled to obtain the discharged electrode plates.

[0086] Depend on Figure 2 It can be seen that the LiF on the electrode surface after discharge in Example 8 is significantly reduced, and some fluorinated carbon is still exposed on the surface after discharge.

[0087] Comparative Example 9 A high-pressure, low-temperature lithium / carbon fluoride battery, differing from Example 8 only in that the electrolyte used is the same as that of Comparative Example 1.

[0088] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material. After the discharge was completed, the battery was disassembled to obtain the discharged electrode plates.

[0089] Depend on Figure 3 It can be seen that there is more LiF on the surface of the electrode after discharge in Comparative Example 9, which adheres to the surface of fluorinated carbon and blocks the ion transport channels.

[0090] Depend on Figure 5 It can be seen that, at room temperature, the introduction of the additive 4-aminophenylboronic acid pinacol ester successfully improved the battery voltage plateau and discharge capacity.

[0091] Example 9 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Example 2.

[0092] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0093] Example 10 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the electrolyte of Example 3.

[0094] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0095] Example 11 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the electrolyte of Example 4.

[0096] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0097] EIS testing was performed on the batteries assembled in Examples 9, 12, and Comparative Example 9, such as... Figure 4 As shown, it can be seen that the battery impedance of Example 9 is the lowest, followed by Example 12, and the impedance of Comparative Example 9 is the highest. This indicates that the introduction of additives effectively reduces the battery impedance and improves the ion transport rate.

[0098] Example 12 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the electrolyte of Example 5.

[0099] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0100] like Figure 6 As shown, the battery performance was tested at -50℃. The voltage plateau of Example 8 was about 2V, which is a significant improvement over the voltage plateau and capacity of Comparative Example 9. The voltage plateau and capacity of Examples 9-12 were also improved to varying degrees.

[0101] Example 13 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the electrolyte of Example 6.

[0102] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0103] Comparative Example 10 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 2.

[0104] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0105] Comparative Example 11 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 3.

[0106] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0107] Comparative Example 12 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 4.

[0108] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0109] Comparative Example 13 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 5.

[0110] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0111] Comparative Example 14 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 6.

[0112] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0113] Comparative Example 15 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 7.

[0114] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0115] The batteries of Example 8, Comparative Examples 9-10, and Comparative Examples 13-15 were tested at -50 °C with a concentration of 0.01 A g. -1 The following discharge test is performed, such as Figure 7 As shown, Example 8 exhibits the highest voltage plateau. The batteries with added 3-aminophenylboronic acid pinacol ester in the electrolyte of Comparative Example 10, added 4,4,5,5-tetramethyl-1,3,2-dihexopentylborane in the electrolyte of Comparative Example 13, and added 3-amino-4-fluorophenylboronic acid pinacol ester in the electrolyte of Comparative Example 15 all showed significantly improved voltage plateaus and capacities compared to the electrolyte of Comparative Example 9 without any additives. However, none of them demonstrated the superior performance improvement of the electrolyte prepared with the additive 4-aminophenylboronic acid pinacol ester.

[0116] Discharge tests were performed on Examples 8-10, Examples 12-13, Comparative Example 9, and Comparative Example 15, as follows: Figure 8 As shown, -60℃, 0.01 Ag -1 The battery performance was tested, and Example 8 showed the highest voltage plateau, while Comparative Example 9 showed the lowest. Examples 9-10 and 12-13 had better voltage plateaus and capacities than Comparative Example 9 and Comparative Example 15, indicating that the electrolyte prepared with the additive 4-aminophenylboronic acid pinacol ester provided by the present invention has excellent performance enhancement.

[0117] Example 14 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the electrolyte of Example 7.

[0118] After the assembled battery was left to stand for 12 hours, it was discharged at room temperature with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0119] Comparative Example 16 A high-pressure, low-temperature lithium / carbon fluoride battery differs from Example 8 only in that the electrolyte used is the same as that in Comparative Example 8.

[0120] After the assembled battery was left to stand for 12 hours, it was discharged at different temperatures with a cutoff voltage of 1.5 V or 1 V. The discharge specific capacity of the battery was calculated using fluorinated carbon in the positive electrode material as the active material.

[0121] like Figure 9 As shown, the battery performance of Example 14 and Comparative Example 16 at 25°C was tested. The voltage plateau of Example 14 was significantly better than that of Comparative Example 16, indicating that the additive 4-aminophenylboronic acid pinacol ester provided by the present invention can be used in a variety of commercial electrolytes and has universality.

[0122] The discharge performance of the batteries of Examples 8, 14, 9, and 16 at 25°C and the discharge performance of the batteries of Examples 8, 9-12, and 14 at -50°C are compared, as shown in Table 1.

[0123] Table 1

[0124] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several modifications and improvements without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A high-pressure, low-temperature lithium / carbon fluoride battery electrolyte, characterized in that, The electrolyte is composed of additives, lithium salts and solvents, wherein the additive is 4-aminophenylboronic acid pinacol ester and the additive accounts for 0.1-2 wt% of the total mass of the electrolyte.

2. The high-pressure, low-temperature lithium / carbon fluoride battery electrolyte according to claim 1, characterized in that, The lithium salt is lithium tetrafluoroborate or lithium hexafluorophosphate.

3. The high-pressure, low-temperature lithium / carbon fluoride battery electrolyte according to claim 1, characterized in that, The concentration of the lithium salt is 0.5-4 mol / L.

4. The high-pressure, low-temperature lithium / fluorinated carbon battery electrolyte according to claim 1, characterized in that, When the lithium salt is lithium tetrafluoroborate, the solvent is propylene carbonate and ethylene glycol dimethyl ether in a volume ratio of 1:1; when the lithium salt is lithium hexafluorophosphate, the solvent is ethylene carbonate and diethyl carbonate in a volume ratio of 1:

1.

5. The high-pressure, low-temperature lithium / carbon fluoride battery electrolyte according to claim 4, characterized in that, The electrolyte is prepared by first mixing the solvents evenly to form a co-solvent, then adding lithium salt and stirring evenly, then adding additives and dissolving them evenly to obtain the electrolyte.

6. A high-pressure, low-temperature lithium / carbon fluoride battery, comprising a positive electrode, a negative electrode, a separator, and an electrolyte, characterized in that, The electrolyte is the high-pressure low-temperature lithium / fluorinated carbon battery electrolyte according to any one of claims 1-6.

7. The high-voltage, low-temperature lithium / carbon fluoride battery according to claim 6, characterized in that, The positive electrode is obtained by dispersing fluorinated carbon positive electrode material, conductive carbon black and binder PVDF in N-methylpyrrolidone at a mass ratio of 8-9:0.5-1:0.5-1, mixing thoroughly, coating on carbon-coated aluminum foil, and drying.

8. The high-voltage, low-temperature lithium / carbon fluoride battery according to claim 6, characterized in that, The negative electrode is made of lithium sheet or lithium strip with a thickness of 50-500 μm.

9. The high-voltage, low-temperature lithium / carbon fluoride battery according to claim 6, characterized in that, The diaphragm is made of PE and has a thickness of 25 μm.

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