Carbon fluoride active material and lithium-carbon fluoride primary battery

Abstract

This invention provides a fluorinated carbon active material and a lithium fluorinated carbon primary battery. The fluorinated carbon active material, after precise fluorination with a composite gas and surface modification treatment, produces a fluorine-carbon atomic molar ratio of 1.3-1.6 and a tap density of 0.6-1.2 g / cm³. 3 The high-fluorine-content, high-taper-density fluorinated carbon material is used; the primary battery consists of a fluorinated carbon positive electrode, a lithium negative electrode, a separator, a non-aqueous electrolyte, rubber-containing tabs, and a shell. When a high-strength, lightweight separator, an aluminum-plastic film shell, and a preferred electrolyte formulation and dosage are comprehensively applied, the resulting lithium primary battery can achieve a specific energy of up to 1200Wh / kg, providing ultra-long working time for electrical equipment and possessing significant application value.

Description

Technical Field

[0001] This invention relates to the field of lithium fluoride carbon battery technology, and in particular to a high specific energy fluoride carbon active material and a lithium fluoride carbon primary battery. Background Technology

[0002] Lithium fluoride carbon (Li / CFx) batteries are the battery system with the highest specific energy among solid electrode chemical power sources, attracting much attention due to their numerous advantages such as high energy density, stable operating voltage, long service life, safety and reliability, and wide operating temperature range. Conventional fluoride carbon materials have an F / C limit of 1, a theoretical specific capacity of 865 mAh / g, and this capacity is difficult to fully realize; the specific energy of lithium fluoride carbon batteries prepared from them is typically below 700 Wh / kg.

[0003] To address the aforementioned technical problems, Chinese patent CN 109148850 A, "A Preparation Method of Fluorinated Graphene Capsules and Their Application in Lithium Primary Batteries," provides a method for preparing fluorinated graphene capsules. Utilizing a three-dimensional network structure of high-curvature graphene capsules containing numerous defects, fluorination yields a non-integer ratio CFx material with an F:C ratio greater than 1:1, where x = 1–2. Simultaneously, the graphene capsule structure promotes deep lithium encapsulation (Li₂F₂). + Due to its properties, fluorinated carbon materials exhibit high specific capacity and specific energy (1303.4 mAh / g, 2547.05 Wh / kg) in button cell experimental batteries. However, graphene capsules are nanoscale, making it difficult to precisely control the fluorine content and CF bond type during the fluorination process. Materials with high fluorination degrees struggle to maintain a high voltage plateau during discharge, resulting in a large capacity contribution at low voltage ranges and thus low specific energy utilization. Furthermore, nanoscale materials have excessively low tap density (typically below 0.1 g / m³). 3 It is difficult to achieve higher specific energy in practical batteries.

[0004] In the paper "Fluorinated graphite nanosheets for ultrahigh-capacity lithium primary batteries," the authors introduced edge defects and -CF2 and -CF3 perfluorinated functional group active sites into graphite nanosheets (NSs), achieving an ultrathin microsheet material with a high fluorine content of 1.34 (F / C = 1.34). At a current density of 10 mA / g, the fluorinated graphite nanosheets achieved a specific capacity of 921 mAh / g. The prepared primary battery achieved capacities of 1021.5 Wh / kg at room temperature and 1116 Wh / kg at 60 °C. Although the highly fluorinated graphite nanosheets exhibited high specific capacity and stable discharge voltage, the overall voltage plateau was relatively low (approximately 2.5 V), which is related to their poor electronic and ion conductivity, resulting in unsatisfactory battery reaction kinetics. The tap density of the graphite nanosheets was also low (generally below 0.3 g / m³). 3To fully utilize the specific energy of a material, a relatively large amount of electrolyte is required.

[0005] Therefore, based on the lithium fluorinated carbon battery system, how to obtain high specific energy fluorinated carbon active materials and how to prepare batteries with even higher specific energy have become current research hotspots and challenges. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a high specific energy fluorinated carbon active material.

[0007] Another technical problem to be solved by the present invention is to provide a lithium fluorinated carbon primary battery using the above-mentioned high specific energy fluorinated carbon active material.

[0008] The technical solution adopted in this invention is:

[0009] A fluorinated carbon active material is prepared from a uniquely structured and abundant carbon source. After precise fluorination and surface modification treatment with a composite gas of fluorine and nitrogen, it produces a fluorine-carbon atomic molar ratio of 1.3-1.6 and a tap density of 0.6-1.2 g / cm³. 3 Specific surface area 300-900 m² 2 / g of high fluorine content, high tap density fluorinated carbon material, the material contains three groups: -CF, -CF2, and -CF3. Among these groups, the proportion of -CF groups is 50%-77%, the proportion of -CF2 groups is 20%-47%, and the proportion of -CF3 groups is 3%-30%. The carbon source is prepared using biomass-based carbon material as a precursor. The carbon source contains abundant unsaturated bonds -C=O, -COH, and -CN. The carbon interlayer spacing D002 in the crystal structure of the carbon source is 0.37-0.385nm.

[0010] The aforementioned fluorinated carbon active material contains a high proportion of -CF2 active groups, with a specific capacity of 950-1000 mAh / g. The molar proportion of half-ionic CF bonds (bond length range of 1.39 Å-1.43 Å) in the -CF and -CF2 groups is 30%-70%. The abundant and highly electrochemically active half-ionic CF bonds enable the material to achieve an average discharge voltage of over 2.85V and a specific energy of 2650Wh / kg-3300Wh / kg.

[0011] Preferably, the specific surface area of ​​the above-mentioned fluorinated carbon active material is 400-700 m². 2 / g.

[0012] Preferably, the above-mentioned fluorinated carbon active material further contains a uniform coating layer on its surface, the coating layer having a mass percentage of 0.5-5%, and the coating layer being composed of carbon or oxides.

[0013] Preferably, the preparation process of the above-mentioned fluorinated carbon active material, wherein the biomass-based carbon material as a precursor includes two main stages: carbonization and activation. The carbonization process includes pyrolysis carbonization or hydrothermal carbonization, and the activation process includes physical activation, chemical activation, or physical-chemical activation.

[0014] Preferably, the fluorination process used in the above-mentioned fluorinated carbon active material is gas-phase fluorination or gas-liquid combined fluorination, the fluorine source is fluorine gas or fluorine atoms, and the fluorination temperature range is room temperature to 600°C.

[0015] Preferably, the fluorination temperature of the above-mentioned fluorinated carbon active material is 200-400℃.

[0016] Preferably, in the above-mentioned fluorinated carbon active material, the biomass-based carbon material is used as a precursor, and one or more of one-dimensional fibrous carbon raw materials, two-dimensional sheet-like carbon raw materials, and three-dimensional porous carbon raw materials are adopted.

[0017] Preferably, in the above-mentioned fluorinated carbon active material, the mass percentages of the one-dimensional fibrous carbon raw material, the two-dimensional sheet-like carbon raw material, and the three-dimensional porous carbon raw material are 0-60%, 0-60%, and 40%-100%, respectively.

[0018] Preferably, in the above-mentioned fluorinated carbon active material, the one-dimensional fibrous carbon raw material is flax, ramie, stem bark, or lotus seedpod.

[0019] Preferably, in the above-mentioned fluorinated carbon active material, the two-dimensional sheet-like carbon raw material is asphalt, maple, Ganoderma lucidum or starch.

[0020] Preferably, the three-dimensional porous carbon raw material of the above-mentioned fluorinated carbon active material is a fruit shell, leaf, bark, fruit peel or seashell, such as bamboo, coconut shell, walnut shell, macadamia nut shell, peanut shell.

[0021] A lithium fluorinated carbon primary battery using the above-mentioned fluorinated carbon active material comprises a fluorinated carbon positive electrode, a lithium negative electrode, a separator, a non-aqueous electrolyte, adhesive tabs, and a casing, achieving a specific energy of 1200 Wh / kg. The fluorinated carbon positive electrode is composed of fluorinated carbon material, a conductive agent, a binder, and a current collector. The fluorinated carbon material contains three groups: -CF, -CF2, and -CF3, with a fluorine-to-carbon atomic ratio of 1.3-1.6, a specific capacity of 950-1000 mAh / g, and a specific energy of 2650-3300 Wh / kg.

[0022] Fluorocarbon materials account for 40%-55% of the mass of batteries.

[0023] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the weight ratio of the fluoride carbon material in the fluoride carbon positive electrode is 88%-95%, and the conductive agent used is one or more of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, conductive carbon black, Ketjen black, acetylene black, nano titanium dioxide, nano silver, nano silver oxide, nano gold, or nano platinum.

[0024] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the current collector is a three-dimensional aluminum mesh formed by stretching metallic aluminum, and the density of the aluminum mesh is 0.1-0.6 mg / cm³. 3 The thickness is 0.1-0.6mm.

[0025] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the aluminum mesh density is 0.4 mg / cm³. 3 Aluminum mesh with a thickness of 0.4mm.

[0026] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the thickness of the positive electrode sheet is 0.5-1.5 mm, and the compaction density is 1.3-2.0 g / cm³. 3 .

[0027] Preferably, in the above-mentioned lithium carbon fluoride primary battery, the positive electrode sheet has a compaction density of 1.5-1.7 g / cm³. 3 .

[0028] Preferably, in the above-mentioned lithium carbon fluoride primary battery, the binder is one or more selected from polyvinylidene fluoride (PVDF), modified polyvinylidene fluoride, polytetrafluoroethylene (PTFE), sodium carboxymethyl cellulose (CMC-Na), lithium carboxymethyl cellulose (CMC-Li), styrene-butadiene rubber (SBR), modified styrene-butadiene rubber, acrylate (PAA), modified acrylate, or polyacrylonitrile.

[0029] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the non-aqueous electrolyte is a solid electrolyte, a gel (or semi-solid) electrolyte, or a liquid electrolyte.

[0030] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the non-aqueous electrolyte is a liquid electrolyte.

[0031] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the solid electrolyte is a polymer-based solid electrolyte, a sulfur-containing compound-based solid electrolyte, or an oxide-based solid electrolyte.

[0032] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the solid electrolyte is a sulfur-containing compound solid electrolyte.

[0033] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the liquid electrolyte is composed of lithium salt, organic solvent, and additives, wherein,

[0034] The lithium salt is one or more of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bisfluorosulfonylimide (LiFSI), lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium difluorophosphate (LiPO2F2), lithium nitrate (LiNO3), lithium perchlorate (LiClO4), lithium difluorodioxolane borate (LiODFB), lithium dioxyborate (LiBOB), or lithium difluorodioxolane phosphate (LiBODFP);

[0035] The organic solvent is one or more of the following: ethylene carbonate (EC), propylene carbonate (PC), 1,2-dimethoxyethane (DME), dioxolane (DOL), tetrahydrofuran (THF), 2-methyltetrahydrofuran (2Me-THF), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (EMC), butyronitrile (BN), γ-butyrolactone (BL), chain carboxylic acid esters (such as ethyl acetate EA, ethyl propionate EP, propyl propionate PP, propyl acetate PA, etc.), fluoroethers or fluoroesters; and one or more of the following: ethylene sulfite (ES), diethyl sulfite (DES), dimethyl sulfite (DMS) or propylene sulfite (PS).

[0036] The additive is one or more of the following: fluoroethylene carbonate (FEC), ethylene sulfate (DTD), 1,3-propanesulfonate lactone (PST), tris(trimethylsilane)borate (TMSB), pyridine, methanedisulfonate methylene ester (MMSD), fluorobenzene (FB), cyclohexylbenzene (CHB), or phosphazene flame retardant additives.

[0037] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the gel-state (or semi-solid) electrolyte is composed of a solid electrolyte and a liquid electrolyte, and the mixing ratio of the two is 1:99-99:1.

[0038] All of the electrolytes mentioned above are existing products.

[0039] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the negative electrode is metallic lithium, and the current collection method of the single lithium negative electrode inside the battery includes leading out metallic lithium, a lightweight nickel mesh or copper foil; the electrode tab material led out from the outside of the battery is nickel, copper or copper plated with nickel.

[0040] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the current collection method of the single lithium negative electrode inside the battery is to draw out metallic lithium.

[0041] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the substrate material of the separator is organic thin film polyimide (PI), polyethylene (PE), polypropylene (PP) or polyethylene terephthalate (PET), and / or a ceramic coating or polymer coating modified separator based on the separator substrate.

[0042] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the porosity of the separator is 40%-50%; and the total thickness of the separator is 6μm-20μm.

[0043] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the outer casing is made of aluminum-plastic composite film, aluminum, aluminum alloy or stainless steel; the shape of the outer casing is cylindrical, square or irregular.

[0044] Preferably, in the above-mentioned lithium fluorocarbon primary battery, the outer casing is made of aluminum-plastic composite film.

[0045] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the thickness of the aluminum-plastic composite film is 50-200 μm.

[0046] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the thickness of the aluminum-plastic composite film is 70-115 μm.

[0047] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the electrode assembly is a stacked structure or a wound structure.

[0048] Preferably, in the above-mentioned lithium fluoride carbon primary battery, the electrode assembly has a stacked structure.

[0049] When the aforementioned lithium fluoride carbon primary battery is made by comprehensively applying a high-strength lightweight separator, an aluminum-plastic film shell, and a preferred electrolyte formulation and dosage, the resulting lithium primary battery can achieve a specific energy of up to 1200Wh / kg, providing an ultra-long working time for electrical equipment and possessing significant application value.

[0050] The beneficial effects of this invention are:

[0051] The fluorinated carbon active material is a high-specific-energy fluorinated carbon material with high tap density, high specific capacity, and good kinetic properties.

[0052] Compared with existing technologies, the fluorinated carbon material provided by this invention contains abundant half-ionic CF bonds (accounting for 30-70%), while the CF bonds in conventional fluorinated carbon materials are mainly covalent, with half-ionic -F bonds generally accounting for less than 20%. The bond length of half-ionic CF bonds is approximately 1.39 Å-1.43 Å, while the bond length of covalent bonds is approximately 1.363 Å-1.39 Å. The longer the bond length, the higher the electrochemical activity; that is, half-ionic CF bonds are more active than covalent CF bonds. The fluorinated carbon provided by this invention contains a high proportion of half-ionic CF bonds, and the discharge platform can reach 3V and above, significantly higher than the 2.5-2.8V discharge platform of conventional materials. Therefore, extremely high specific energy can be obtained.

[0053] The fluorinated carbon provided by this invention uses a mixture of biomass carbon materials as a precursor. This type of precursor produces carbon sources that are not only abundant and inexpensive, but also rich in unsaturated bonds such as -C=O, -COH, and -CN. These bonds facilitate the formation of -CF2 groups during fluorination, increasing the material's specific capacity. Furthermore, the resulting carbon source has a carbon interlayer spacing of 0.37-0.385 nm, significantly larger than the 0.335-0.35 nm spacing of conventional graphite. This facilitates the formation of highly electrochemically active semi-ionic CF bonds during fluorination. Moreover, the low-temperature fluorination process, operating at room temperature to 600°C, also promotes the generation of highly active semi-ionic CF bonds, increasing the proportion of semi-ionic CF bonds in the material.

[0054] The carbon source provided by this invention is more likely to form semi-ionic CF bonds than conventional graphite. This is because it is mainly composed of graphite microcrystals and amorphous regions, containing a large number of microporous structures and high curvature structures. The specific influencing mechanism is as follows: (1) There are many edge structures in the graphite microcrystal region. The carbon in the edge structure has unpaired electrons, which are easy to react with fluorine atoms, that is, they can carry out fluorination reaction at a lower temperature, maintain the overall conjugated structure of the carbon material, and help reduce the bond energy of the fluorine-carbon bond, thereby constructing a semi-ionic carbon-fluorine bond; (2) The large number of microporous structures in the amorphous region provides reactive sites, which is conducive to the insertion of fluorine atoms and facilitates fluorination at low temperature; (3) There are a large number of spatially distorted and high-curvature carbon structures in the amorphous carbon material, and these positions are also easy to generate semi-ionic bonds with longer bond lengths.

[0055] Using lightweight three-dimensional aluminum mesh as a current collector can achieve the following two beneficial effects: (1) Lightweighting, increasing the mass ratio of fluorinated carbon active material in the electrode; (2) Thick electrodes with a thickness of 0.5-1.5 mm can be prepared, because the three-dimensional aluminum mesh can be firmly embedded in the thick film to form a three-dimensional conductive network. While obtaining a good current collection effect, it can also improve the reaction kinetic characteristics, resist deformation, and effectively ensure the full utilization of the energy of fluorinated carbon materials.

[0056] In the high-energy-density lithium fluoride primary battery provided by the present invention, the internal current collection of the lithium negative electrode is preferably a self-contained metal lithium sheet for direct current collection. Compared with the current collection methods of copper foil, copper strip, nickel strip, or stainless steel strip used in conventional lithium primary batteries, the following beneficial effects can be obtained: (1) Lighter weight, improving the specific energy of the battery; (2) Greatly reducing the risk of current interruption caused by the consumption of negative electrode metal lithium at the end of battery discharge; (3) No need to stick tape at the current collection position, which is conducive to the full utilization of the capacity of fluoride carbon at the corresponding position; (4) Since metal lithium has the characteristic of easy adhesion, the metal lithium can be firmly bonded together with a small pressure, so the preparation process of the negative electrode sheet is simpler and easier to operate.

[0057] The high-energy-density lithium fluoride primary battery provided by this invention uses an electrolyte solvent comprising one or more of vinyl sulfite (ES), diethyl sulfite (DES), dimethyl sulfite (DMS), and propylene sulfite (PS). This sulfonate solvent also has electrochemical activity and can use the product of carbon discharge (i.e., carbon) as a carrier to undergo a lithium fusion reaction with metallic lithium. The discharge plateau of this reaction is 2-2.4V, and the discharge specific energy of the sulfonate solvent can reach 200-400Wh / kg. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of a stacked soft-pack lithium fluoride primary battery structure as described in Example 1;

[0059] Figure 2 The image shows the discharge curve of the battery at room temperature (0.01C) obtained in Example 1 of this invention. Detailed Implementation

[0060] To further illustrate the present invention, the following embodiments are provided for detailed explanation:

[0061] Example 1

[0062] like Figure 1 As shown, a high-energy-density lithium fluoride primary battery comprises a negative electrode sheet 1 with a negative electrode tab 3 welded on, and wrapped in a separator 2 to form a bag; a positive electrode sheet 4 with a positive electrode tab 6 welded on, and wrapped in a separator 5 to form a bag; the negative electrode sheet 1 and the positive electrode sheet 2 are stacked sequentially to obtain a cell electrode assembly 9; the negative electrode tab 3 and the positive electrode tab 4 are welded together with a negative electrode tab 7 containing hot melt adhesive and a positive electrode tab 8 containing hot melt adhesive, respectively; the electrode assembly 9 is placed in an outer packaging shell 10 and sealed to obtain a battery 11. The manufacturing method adopts a stacked electrode assembly structure design, the battery has a square external structure, and the outer shell uses an aluminum-plastic film. The specific preparation method is as follows:

[0063] (1) Preparation of fluorinated carbon material A:

[0064] Shells were selected as raw materials, dried, crushed into small pieces, soaked in 1M HCl solution for 2 hours, then washed with deionized water, and dried in a drying oven for 8 hours to remove inorganic minerals. The shells were then placed in a tube furnace and pretreated at 150℃ for 2 hours under argon protection, followed by calcination at 900℃ for 3 hours to complete the carbonization reaction. A 5% KOH solution was used as an activator and stirred with the carbonized product for 4 hours. The product was then dried at 100℃ under vacuum for 10 hours and then ground to obtain carbon source A.

[0065] Next, carbon source A was placed in a sealed fluorination reaction apparatus. The apparatus was evacuated to a pressure of 100-200 Pa, and the temperature was increased to 350°C at a rate of 5°C / min, and maintained for 1 hour. Then, at 350°C, a mixture of fluorine and nitrogen gas (fluorine volume fraction of 5%) was introduced at a rate of 10-15 ml / min. After reacting for 10 hours, the fluorine and nitrogen gas mixture was removed from the apparatus, and nitrogen gas was introduced back into the apparatus. After natural cooling to room temperature, crude fluorinated carbon was obtained. The crude fluorinated carbon was then surface-modified with carbon coating using sucrose as the carbon source, with the coating amount controlled at 0.8-1% wt, to obtain fluorinated carbon material A.

[0066] (2) Preparation of fluorinated carbon material B:

[0067] Maple wood was selected as the raw material, dried, crushed into small pieces, soaked in 1M HCl solution for 2 hours, then cleaned with deionized water, and dried in a drying oven for 8 hours to remove inorganic minerals. It was then placed in a tube furnace and pretreated at 150℃ for 2 hours under argon protection, followed by calcination at 800℃ for 3 hours to complete the carbonization reaction. A 5% KOH solution was used as an activator and stirred with the carbonized product for 4 hours. The product was then dried at 100℃ under vacuum for 10 hours and then ground to obtain carbon source B.

[0068] Next, carbon source B was first mixed with SbF5, and then placed in a Monel reactor and reacted at 150°C for 2 hours. This allowed SbF5, with its Lewis acid properties, to fully penetrate the carbon material, forming new fluorination sites and accelerating subsequent fluorination reactions. The material was then placed in a 300°C reaction apparatus, and a mixture of fluorine and nitrogen gas (fluorine volume fraction 5%) was introduced at a rate of 15-20 ml / min. After reacting for 3-4 hours, the fluorine and nitrogen gas mixture was removed from the reaction apparatus, and nitrogen gas was introduced back into the apparatus. The mixture was allowed to cool naturally to room temperature to obtain crude fluorinated carbon. The crude fluorinated carbon product was then surface-modified with carbon coating using sucrose as the carbon source, with the coating amount controlled at 0.5-0.8% wt, to obtain fluorinated carbon material B.

[0069] (3) Preparation of fluorinated carbon cathode sheet:

[0070] Fluorocarbon materials A and B were mixed uniformly at a mass ratio of 50:50 to obtain the positive electrode active material CFx. The positive electrode formulation was CFx:SP:carbon nanotubes (CNTs):oligolayer graphene:PTFE:PAA = 90:2.5:1.4:0.1:5:1 (mass ratio). Using ethanol and deionized water as solvents, a film-forming wet process was used to prepare a film with a thickness of 0.8-0.9 mm and a density of 0.9-1.0 mg / cm³. 3 The positive electrode film is then dried at 60°C for 8 hours.

[0071] A density of 0.4 mg / cm³ was used. 3 A 0.4mm thick aluminum mesh is used as the positive electrode current collector (a 0.1mm thick × 7mm wide × 15mm long aluminum strip is welded to one side of the aluminum mesh as an electrode tab for current guiding). A sandwich structure of two positive electrode films sandwiching one aluminum mesh is then formed by pressing them together using a roller press, resulting in a surface loading of 140mg / cm². 2 The compacted density is 1.65 ± 0.05 g / cm³. 3 A positive electrode sheet with a thickness of approximately 0.85 mm is cut into a predetermined size of 60 mm wide × 70 mm long. Finally, the positive electrode sheet is vacuum dried at 130°C for 12 hours.

[0072] (4) Preparation of negative electrode sheet

[0073] The negative electrode uses a lithium metal sheet with a purity of ≥99.9% and a thickness of 0.32mm. It is punched into a sheet shape of 61mm wide × 71mm long with a 7mm wide × 10mm long tab using a punching die, which is a lithium sheet self-collecting structure.

[0074] (5) Battery manufacturing

[0075] The electrode assembly features a stacked structure with a flexible aluminum-plastic film outer casing. The positive electrode tabs are made of 0.1×6mm aluminum strip, and the negative electrode tabs are made of 0.1×6mm nickel strip.

[0076] A 12μm thick polypropylene separator is used to stack five positive electrode sheets, four double-layer negative electrode sheets (total lithium sheet thickness 0.64mm), and two single-layer negative electrode sheets (lithium sheet thickness 0.32mm) in a Z-shaped structure to form an electrode assembly with dimensions of 7.6mm thick × 63mm wide × 74mm long. The positive and negative electrode tabs are 0.1mm thick × 7mm wide composite hot melt adhesive tabs, made of aluminum and nickel, respectively. The outer shell uses a flexible aluminum-plastic film with a thickness of 113μm, and the battery is heat-sealed on three sides, with one side reserved as a liquid injection port.

[0077] The battery was filled with electrolyte, which was formulated as follows: PC:DME:ethylene sulfite (ES):dimethyl sulfite (DMS) = 20:30:30:20 (weight ratio). LiTFSI was used as the lithium salt with a concentration of 1.0 mol / L, and the battery filling volume was 17.0 g. Finally, the battery was vacuum-sealed to obtain a battery with dimensions of approximately 7.9 mm thick × 65 mm wide × 84 mm long.

[0078] Example 2:

[0079] The difference from Example 1 lies in the electrolyte injected into the battery. The electrolyte solvent composition is PC:DME:DOL = 40:30:30 (weight ratio), and LiClO4 is used as the lithium salt with a concentration of 1.0 mol / L. The other preparation processes are the same as in Example 1.

[0080] Example 3:

[0081] The difference from Example 1 is that the fluorinated carbon used in the battery preparation is a mixture of fluorinated carbon material A and fluorinated carbon C in a mass ratio of 50:50.

[0082] The preparation method of fluorinated carbon C is as follows:

[0083] Lotus pods were selected as raw materials. After drying and crushing into small pieces, they were soaked in 1M HCl solution for 2 hours, then washed with deionized water and dried in a drying oven for 8 hours to remove inorganic minerals. They were then placed in a tube furnace and pretreated at 150℃ for 2 hours under argon protection, followed by calcination at 700℃ for 3 hours to complete the carbonization reaction. A 5% KOH solution was used as an activator and stirred with the carbonized product for 4 hours. The product was then dried at 100℃ under vacuum for 10 hours and then ground to obtain carbon source C.

[0084] Next, carbon source C was first mixed with SbF5, and then placed in a Monel reactor and reacted at 150°C for 2 hours. This allowed SbF5, with its Lewis acid properties, to fully penetrate the carbon material, forming new fluorination sites and accelerating subsequent fluorination reactions. The material was then placed in a 280°C reaction apparatus, and a mixture of fluorine and nitrogen gas (5% fluorine by volume) was introduced at a rate of 15-20 ml / min. After reacting for 2-3 hours, the fluorine and nitrogen gas mixture was removed from the reaction apparatus, and nitrogen gas was introduced back in. The mixture was allowed to cool naturally to room temperature to obtain crude fluorinated carbon. The crude fluorinated carbon product was then surface-modified with carbon coating using sucrose as the carbon source, with the coating amount controlled at 0.5-0.8% wt, to obtain fluorinated carbon material C.

[0085] The other preparation process is the same as in Example 1.

[0086] Example 4:

[0087] The difference from Example 1 is that the fluorinated carbon used in the battery preparation is 100% fluorinated carbon material A. The other preparation processes are the same as in Example 1.

[0088] Example 5:

[0089] The difference from Example 1 is that the fluorinated carbon used in the battery preparation is 100% fluorinated carbon material B. The other preparation processes are the same as in Example 1.

[0090] Example 6:

[0091] The difference from Example 1 is that the fluorinated carbon used in the battery preparation is 100% fluorinated carbon material C. The other preparation processes are the same as in Example 1.

[0092] Comparative Example 1:

[0093] Similar to Example 1, the same fluorinated carbon material A and fluorinated carbon material B were used. Other battery fabrication processes are as follows:

[0094] (1) Preparation of fluorinated carbon cathode sheet:

[0095] Fluorinated carbon materials A and B were mixed uniformly at a mass ratio of 50:50 to obtain the positive electrode active material CFx. The positive electrode formulation was CFx:SP:carbon nanotubes (CNTs):oligolayer graphene:PVDF = 91:2.5:1.4:0.1:5 (mass ratio). A slurry was prepared using N-methylpyrrolidone (NMP) as a solvent. The slurry was uniformly coated onto a 12μm thick aluminum foil using a roller coating process, and the electrode surface loading was controlled at 20±0.6mg / cm². 2 After rolling, the electrode density is controlled at 1.65±0.05 g / cm³. 3 The thickness is approximately 133 μm. The electrode sheets are punched to a predetermined size of 60 mm wide × 70 mm long, with each electrode sheet containing a 7 mm wide × 10 mm long aluminum foil tab for current guiding. Finally, the positive electrode sheets are vacuum dried at 130 °C for 12 hours.

[0096] (2) Preparation of negative electrode sheet

[0097] The negative electrode uses a lithium metal sheet with a purity of ≥99.9% and a thickness of 0.1mm. It is punched into a sheet shape of 61mm wide × 71mm long with a 7mm wide × 10mm long tab using a punching die, which is a lithium sheet self-collecting structure.

[0098] (3) Battery fabrication

[0099] The electrode assembly features a stacked structure with a flexible aluminum-plastic film outer casing. The positive electrode tabs are made of 0.1×6mm aluminum strip, and the negative electrode tabs are made of 0.1×6mm nickel strip.

[0100] A 12μm thick polypropylene separator is used, and 35 positive electrode sheets and 36 negative electrode sheets are stacked in a Z-shape to form an electrode assembly with dimensions of 9.1mm thick × 63mm wide × 74mm long. The positive and negative electrode tabs are 0.1mm thick × 7mm wide composite hot melt adhesive tabs, made of aluminum and nickel, respectively. The outer shell is made of flexible aluminum-plastic film with a thickness of 113μm, and the battery is sealed on three sides using a heat-sealing machine, with one side reserved as an electrolyte filling port.

[0101] The battery was filled with electrolyte, with a solvent composition of PC:DME:DOL = 40:30:30 (weight ratio). LiClO4 was used as the lithium salt, with a lithium salt concentration of 1.0 mol / L, and the battery filling volume was 25.0 g. Finally, the battery was vacuum sealed to obtain a battery with dimensions of approximately 9.4 mm thick × 65 mm wide × 84 mm long.

[0102] Comparative Example 2:

[0103] The difference from Example 1 is the use of commercially available fluorinated carbon material. The other preparation processes are the same as in Example 1.

[0104] Comparative Example 3:

[0105] Commercially available fluorinated carbon material (number D) was used. The electrode and battery fabrication processes were the same as those in Comparative Example 1.

[0106] Test example:

[0107] (1) Characterization and testing of fluorinated carbon materials

[0108] The tap density of the above-mentioned fluorinated carbon materials was tested using a tap density meter, and the specific surface area was tested using the BET method. The results are shown in Table 1.

[0109] Table 1 Physical properties of several fluorocarbons

[0110]

[0111] The fluorine-to-carbon ratio, carbon-fluorine bond type and atomic percentage of fluorinated carbon materials were determined by XPS analysis. The results are shown in Table 2.

[0112] Table 2 Comparison of Composition Data for Several Fluorocarbons

[0113]

[0114]

[0115] The discharge performance of fluorinated carbon materials was tested using CR2325 button batteries. Fluorinated carbon (CFx): conductive agent (SP): binder (PVDF) were mixed in a ratio of 85:10:5, ball-milled until homogeneous, and then coated onto carbon-coated aluminum foil. The mixture was then die-cut into round sheets to obtain the fluorinated carbon positive electrode. A 20 μm thick polyethylene separator was used, and a 0.1 mm thick lithium sheet was used as the negative electrode. The electrolyte was 1 M LiClO4 with a PC:DME:DOL ratio of 40:30:30 (by weight). The experimental batteries were discharged at 0.01C to 1.5V, and their discharge capacity, specific capacity, and specific energy were calculated. The results are shown in Table 3.

[0116] Table 3 Performance parameters of fluorocarbon materials

[0117]

[0118] (2) Battery performance test

[0119] After aging the batteries prepared in the above examples and comparative examples at a high temperature of 45°C for 2 days, they were discharged at a constant current of 0.26 amps (discharge rate of 0.01C) at room temperature with a cutoff voltage of 1.0V. Table 4 shows the comparison of battery discharge results.

[0120] Table 4 Battery discharge results at 0.01C

[0121]

[0122] The comparative test results above show that the fluorine-carbon atomic molar ratios of the three fluorinated carbon materials provided in this embodiment are 1.34, 1.47, and 1.51, respectively. The provided fluorinated carbon materials contain a high proportion of electrochemically active CF and C-F2 groups, with a specific capacity of over 950 mAh / g, which is much higher than the fluorine-carbon ratio of 1.03 and the specific capacity of 843.8 mAh / g of commercially available high-specific-energy fluorinated carbon materials. At the same time, since the proportion of semi-ionic CF in the CF group is over 48%, the electrochemical activity is high, and the average discharge voltage reaches 2.89-2.93V. Therefore, the specific energies of the three fluorinated carbon materials reach 2792, 2842, and 2878 Wh / kg, respectively.

[0123] Furthermore, the fluorinated carbon material provided by this invention utilizes a special densified carbon source, resulting in a tap density of 0.75-0.92 g / cm³. 3 Compared to the 0.97 g / cm³ of conventional high-energy-density fluorocarbon materials... 3The positive electrode sheet prepared using the thick electrode provided in this embodiment has a fluorinated carbon active material content of 45%-47% by mass in the battery, which is much higher than that of electrodes prepared by conventional coating processes, thus significantly improving the battery's specific energy. By modifying the surface of the above-mentioned fluorinated carbon material with 0.5%-1% (by mass) surface carbon coating, combining it with additives such as single-walled carbon nanotubes and conductive carbon black in the electrode, and using a combination of two types of fluorinated carbon, the specific energy of the high-energy fluorinated carbon material is fully utilized in practical batteries. When comprehensively applying a high-strength lightweight separator, an aluminum-plastic film shell, and a preferred electrolyte formulation and dosage, the resulting lithium primary battery achieves a specific energy of over 1100 Wh / kg. Meanwhile, the high-energy-density lithium primary battery provided by this invention innovatively adopts a multi-electrolyte electrolyte formulation with LiTFSI as the lithium salt and ethylene sulfite (ES) and dimethyl sulfite (DMS) as the main solvents. These two special solvent components can discharge in the range of 2.2-2.4V, using fluorinated carbon reaction products as a carrier, contributing a certain capacity and helping the battery discharge specific energy to reach 1205.9Wh / kg, which is far higher than the specific energy level that conventional fluorinated carbon lithium primary batteries can achieve.

[0124] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention. All technical improvements and modifications made by those skilled in the art based on the technical solution of the present invention are considered to be within the scope of protection of the present invention.

Claims

1. A fluorinated carbon active material, characterized in that: The fluorine-to-carbon atomic molar ratio is 1.3-1.6, and the tap density is 0.6-1.2 g / cm³. 3 Specific surface area 300-900 m² 2 / g of high fluorine content and high tap density fluorinated carbon material contains three groups: -CF, -CF2, and -CF3. Among these groups, the proportion of -CF groups is 50%-77%, the proportion of -CF2 groups is 20%-47%, and the proportion of -CF3 groups is 3%-30%.

2. The fluorinated carbon active material according to claim 1, characterized in that: The specific surface area is 400-700 m² 2 / g.

3. The fluorinated carbon active material according to claim 1, characterized in that: Its surface also contains a uniform coating layer, the mass percentage of which is 0.5-5%, and the coating layer is composed of carbon or oxides.

4. A lithium fluoride carbon primary battery using the fluoride carbon active material according to claim 1, characterized in that: The battery comprises a fluorinated carbon positive electrode, a lithium negative electrode, a separator, a non-aqueous electrolyte, adhesive tabs, and a casing, with a specific energy reaching 1200 Wh / kg. The fluorinated carbon positive electrode is composed of the fluorinated carbon material, a conductive agent, a binder, and a current collector. The fluorinated carbon material contains three groups: -CF, -CF2, and -CF3, with a fluorine-to-carbon atomic ratio of 1.3-1.6, a specific capacity of 950-1000 mAh / g, and a specific energy of 2650-3300 Wh / kg.

5. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The weight ratio of the fluorinated carbon material in the fluorinated carbon cathode is 88%-95%, and the conductive agent used is one or more of the following: single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, conductive carbon black, Ketjen black, acetylene black, nano titanium dioxide, nano silver, nano silver oxide, nano gold, or nano platinum.

6. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The current collector is a three-dimensional aluminum mesh formed by stretching metallic aluminum, and the density of the aluminum mesh is 0.1-0.6 mg / cm³. 3 The thickness is 0.1-0.6mm.

7. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The positive electrode sheet has a thickness of 0.5-1.5 mm and a compaction density of 1.3-2.0 g / cm³. 3 .

8. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The negative electrode is metallic lithium. The charging method of the single lithium negative electrode inside the battery includes leading out metallic lithium, lightweight nickel mesh or copper foil; the electrode tabs led out outside the battery are made of nickel, copper or copper plated with nickel.

9. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The porosity of the diaphragm is 40%-50%; the total thickness of the diaphragm is 6μm-20μm.

10. The lithium fluoride carbon primary battery according to claim 4, characterized in that: The outer shell is made of aluminum-plastic composite film, and the thickness of the aluminum-plastic composite film is 50-200um.

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