All-weather double-high lithium / carbon fluoride battery as well as preparation method and application thereof

Abstract

The invention relates to the field of lithium primary batteries, in particular to an all-weather double-high lithium / carbon fluoride battery as well as a preparation method and application thereof. According to the invention, mixed acid pretreatment is carried out on the surface of CFx, an oxygen-containing functional group is introduced for surface oxygen modification, and the components of a discharge product are obviously changed through the design of a low-melting-point electrolyte, so that the lithium / carbon fluoride primary battery which can be used in all weathers is designed. The technical problems that a traditional Li / CFx primary battery electrolyte is high in melting point, high in viscosity, slow in ion transport kinetics at low temperature, high in electrode / electrolyte interface resistance and the like are solved, and the energy density and the power density of the Li / CFx primary battery in a wide temperature range are comprehensively improved. The preparation process of the electrolyte is simple, the yield is high, and the electrolyte is suitable for large-scale production and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium primary batteries, in particular to an all-weather, double-high lithium / carbon fluoride battery and its preparation method and application. BACKGROUND

[0002] At present, with the development of economy, various electronic products need to use batteries. Among them, lithium primary batteries are widely used in military and civilian devices such as water meters, watches, seismometers, radio frequency selectors, unmanned aerial vehicles, torpedoes, launch vehicles, medical devices, etc. Lithium / carbon fluoride (Li / CF x ) battery is currently the lithium primary battery with the highest theoretical specific energy, and its theoretical mass specific energy can reach 2180 Wh / kg (lithium / thionyl chloride battery: 1470 Wh / kg, lithium / manganese dioxide battery: 1005 Wh / kg). Li / CF x Battery has the advantages of safety and reliability, low self-discharge rate, stable voltage, high and low temperature resistance, etc., and has broad application prospects in military and civilian energy storage devices. With the continuous development of society, Li / CF x Battery is required to be applied in more and more extreme environments such as polar exploration, space exploration and deep sea exploration, which puts forward requirements for the high and low temperature performance of the battery. The electrolyte is the most important part of the battery, which is in direct contact with other parts of the battery and affects the temperature adaptation performance of the battery.

[0003] The traditional lithium / carbon fluoride battery usually uses a carbonate-based electrolyte system with carbonate solvents (such as ethylene carbonate EC, dimethyl carbonate DMC). This type of electrolyte has high ionic conductivity and good electrochemical stability at room temperature. However, in low temperature environment, the viscosity of carbonate solvents increases sharply, the lithium ion migration rate decreases significantly, and the ionic conductivity of the electrolyte decreases significantly. In addition, the interfacial impedance between the electrolyte and the electrode material at low temperature increases significantly, further hindering the electrochemical reaction kinetics process. Especially in lithium / carbon fluoride batteries, the electrochemical reaction of carbon fluoride positive material itself has a high activation energy, and the reaction rate is further slowed down at low temperature, resulting in a significant deterioration of the discharge performance of the battery.

[0004] In order to solve the above problems, a lot of preliminary research has been done on the electrode materials and electrolytes of lithium / carbon fluoride primary batteries, and related technical methods have been developed. For example, patent CN202410575018 discloses a Li / CF xBattery electrolyte with good anti-reduction stability and low viscosity. By adjusting the ratio of cyclic ether to chain ether solvent in the ether solvent, the electrolyte can maintain high conductivity and low viscosity at low temperature, thereby improving the low temperature performance of the electrolyte. However, the electrolyte in this patent contains fluorine, and the preparation process is low in work efficiency and may cause environmental pollution.

[0005] Patent CN202410502529 discloses a kind of small molecule complex additive electrolyte for lithium / carbon fluoride primary battery and its application, with small molecule benzylamine boron trifluoride complex as additive, based on boron-amine synergistic effect, benzylamine and boron trifluoride have boron-nitrogen complex bond (B←N), which has isoelectronic property with C-C bond, and contains a large dipole, using the boron-nitrogen complex bond, the N on amine group carries positive charge, the charge attraction between N and F - Self aggregation to amine group, promote the complexation reaction between boron trifluoride and F - More rapid, which can greatly improve the discharge capacity and discharge platform of lithium / carbon fluoride primary battery at high rate. However, the Li / CF x Battery rate performance is not significantly improved and the temperature zone is narrow, which is difficult to be widely applied.

[0006] Patent CN202410479874 discloses a high-entropy electrolyte for lithium / carbon fluoride battery and its preparation method and application. Compared with single salt electrolyte, the chelation of ether solvent and lithium ion in high-entropy electrolyte is enhanced, which slows down the desolvation process and improves the reaction potential of the second platform. In addition, the conductivity, transference number and diffusion coefficient of lithium ion are better than those of single salt electrolyte, which accelerates the diffusion of lithium ion and speeds up the discharge reaction of carbon fluoride. Finally, the discharge capacity and energy density of lithium / carbon fluoride battery are improved. However, the high-entropy electrolyte uses multiple solvents and additives, which significantly increases the preparation cost and makes it difficult to be widely applied. Moreover, the mixture of multiple chemicals makes the recycling and treatment of electrolyte more complex and costly.

[0007] Patent CN2023116511114 uses potassium ion electrolyte as low-temperature electrolyte for Li / CF x Battery to improve its low-temperature performance. Because the Stokes radius of K + is smaller than that of Li + , the potassium ion electrolyte has faster electrochemical reaction kinetics, which can reduce polarization and improve ion intercalation rate, playing a dual role in ion intercalation reaction mechanism and discharge product nucleation growth. Reducing the reaction energy barrier of early electrochemical reaction, K + containing electrolyte as Li / CF xLow-temperature battery electrolytes may have better low-temperature discharge capabilities. However, the introduction of potassium ion electrolytes into lithium batteries may form unstable phases such as lithium-potassium alloys, increasing the risk of internal short circuits and thermal runaway in batteries.

[0008] In summary, the methods reported so far all involve multi-phase complex electrolyte preparation and cathode material fluorination process, and the improvement effect of electrolyte adaptability in a wide temperature range is very limited, making it difficult to meet various application scenarios. Generally, temperature reduction will lead to the x The viscosity of the battery electrolyte increases, the conductivity decreases, and the impedance increases sharply, which in turn slows the battery's internal dynamics and reduces its capacity. Rising temperatures cause the electrolyte to volatilize, increasing the battery's polarization effect. The discharge product is lithium fluoride (LiF). LiF has extremely low ionic and electronic conductivity. Once formed on the positive electrode surface, it hinders the diffusion of lithium ions and electron transport, resulting in increased interfacial resistance, poor reaction kinetics, and generally causing expansion and disordering of the carbon fluoride structure.

[0009] Therefore, there is an urgent need to develop a lithium / carbon fluoride primary battery and electrolyte system that is suitable for a wide temperature range, which is of great significance for the research and development of all-weather lithium / carbon fluoride primary batteries. Summary of the Invention

[0010] To achieve one of the above objectives, the present invention provides an all-weather, dual-high type lithium / carbon fluoride battery and its preparation method and application. x The surface is pretreated with mixed acid, oxygen-containing functional groups are introduced for surface oxygen modification, and the composition of the discharge product is significantly changed by designing a low-melting-point electrolyte. This results in a lithium / carbon fluoride primary battery that can be used around the clock. The technical solution of the present invention is achieved as follows: In the first aspect, the present invention provides an all-weather, dual-high type lithium / carbon fluoride battery, comprising the following components: surface oxygen-modified CF x Positive electrode material and electrolyte, wherein the surface oxygen-modified CF x The positive electrode material is original CF x The positive electrode material is obtained by mixed acid pretreatment.

[0011] Preferably, the mixed acid comprises a mixed solution prepared from concentrated sulfuric acid and concentrated nitric acid.

[0012] Preferably, the surface oxygen modified CF x The preparation method of the positive electrode material comprises the following steps: A1. The original CF with lower fluorination degree xThe positive electrode material (fluorocarbon element ratio F:C = 0.6:1) is dispersed in a mixed acid solution prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a volume ratio of (2-4):1, and is condensed and refluxed at 80-120℃ for 8-12h, with stirring during the refluxing process; Preferably, the concentrated nitric acid in the mixed acid is the main body of the reaction, providing O, H and other groups, but too high a proportion of nitric acid will excessively oxidize the carbon-based skeleton, reducing the integrity of the product structure, and also produce CO2, NO2 and other gases, causing excessive reaction of the material, and due to the intense heat release, there is also a certain safety risk; and the concentrated sulfuric acid has a strong dehydrating ability, and can generate NO 2+ with HNO3, and the generated NO 2+ efficiency is reduced, and the reaction degree is limited, and too high a concentration will increase the viscosity of the acid mixture, limit diffusion, and cause uneven modification; A2, after the reaction is completed, the reaction solution is washed and filtered, the residual acid in the reaction solution is removed, the pH of the filtrate is adjusted to 7, and the oxygen-modified fluorocarbon material, i.e., the oxidized fluorocarbon (O-CF x ) is obtained after vacuum drying at 80℃.

[0013] Preferably, the components of the electrolyte include lithium salt, cyclic carbonate solvent, linear carboxylate solvent and ether solvent.

[0014] Preferably, the lithium salt includes one or more of lithium tetrafluoroborate (LiBF4), lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonylimide (LiFSI), lithium bis(oxalato)borate (LiBOB), lithium perchlorate (LiClO4), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

[0015] Preferably, the cyclic carbonate solvent includes one or more of ethylene carbonate (EC), propylene carbonate (PC) and vinylene carbonate (VC), the linear carboxylate solvent includes one or more of methyl formate (MF), methyl acetate (MA), methyl butyrate (MB) and methyl propionate (MP), and the ether solvent includes one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran (2-MeTHF), 1,3-dioxolane (DOL) and 4-methyl-1,3-dioxolane.

[0016] Further preferably, in the components of the electrolyte, the volume ratio of the cyclic carbonate solvent, the ether solvent and the linear carboxylate solvent is 1:1:(1-16).

[0017] Further preferably, the preparation method of the electrolyte includes the following steps: B1, 1 mol / L lithium perchlorate (LiClO4) is dissolved in cyclic carbonate solvents, linear carboxylate solvents and ether solvents respectively, and stirred in an argon atmosphere glove box until completely dissolved, and the stirring rate is 300-400 r / min; B2, the above three solutions are mixed and stirred in an argon atmosphere glove box, and the stirring rate is 300-400 r / min, to obtain the electrolyte.

[0018] In a second aspect, the application provides a preparation method of the all-weather and double-high lithium / carbon fluoride battery, comprising the following steps: S1, the CF x is surface oxygen modified. x The positive electrode material (O-CF x ), the conductive agent (Super P) and the binder (PVDF) are poured into a mortar in a mass ratio of 8:1:1 for grinding and mixing, 3wt.% of PVDF (solvent: NMP) is further added for grinding to obtain a viscous and uniform black slurry, then a 50µm doctor blade is used to uniformly coat the slurry on aluminum foil, and the aluminum foil is dried at 60℃ for 24h to obtain a positive electrode sheet. S2, a CR2025 button cell is assembled in an argon atmosphere glove box in the order of negative electrode shell, lithium metal sheet, first electrolyte layer, polypropylene (PP) diaphragm, second electrolyte layer, positive electrode sheet, gasket, spring, and positive electrode shell, to obtain the battery, marked as Li / O-CF x primary battery.

[0019] Preferably, the first electrolyte layer and the second electrolyte layer are the same, and both are obtained by the above preparation method.

[0020] In a third aspect, the application provides an application of the all-weather and double-high lithium / carbon fluoride battery in the field of lithium primary batteries.

[0021] Compared with the prior art, the application has the following advantages: (1) After the positive electrode material of the application is modified by mixed acid containing oxygen functional groups, CF x When reacting with lithium, part of Li reacts with surface oxygen groups to form Li2CO3 instead of all LiF. The Li2CO3 layer can provide a better ion transmission channel, effectively reducing the internal resistance and polarization. Li2CO3 can form a uniform and stable passivation layer on the cathode surface, inhibiting side reactions. At the same time, Li2CO3 accelerates the transmission rate of lithium ions and electrons, which can effectively improve the discharge current capacity of the cathode and shorten the polarization time.

[0022] (2) The 1,3-dioxolane (DOL) and methyl propionate (MP) in the electrolyte have extremely low freezing points, and have low viscosity at low temperature, which can greatly reduce the freezing point of the electrolyte, so that the electrolyte still remains liquid at extremely low temperature, avoids crystallization or phase separation, and thus ensures that the battery can work normally in cold environment.

[0023] (3) The propylene carbonate (PC) in the application forms a first layer of solvation structure around Li + , and the DOL and MP mixed solvent form a second layer of solvation structure, and the double-layer solvation system realizes dynamic balance of ion-solvent interaction by adjusting the interaction between solvents and the overall dielectric constant, and optimizes the ion transport kinetics performance of the electrolyte.

[0024] (4) The PC molecules in the application can be cooperatively embedded into the CF + layer together with Li x to form a "solvated lithium" structure of Li x (PC) y C6 complex, and this co-embedding expands the interlayer spacing of the CF x , which is beneficial to more sufficient discharge and further improves the capacity and rate performance of the battery.

[0025] (5) The preparation process of the electrolyte in the application is simple, has high yield, is suitable for large-scale production, and has broad application prospect. The electrolyte prepared by the application can effectively improve the wide temperature zone (-40℃~60℃) discharge performance of Li / CF x primary battery, and the application solves the technical problems of high melting point, high viscosity, slow ion transport kinetics at low temperature, and high electrode / electrolyte interface resistance of the electrolyte of the traditional Li / CF x primary battery, and comprehensively improves the energy density and power density of the Li / CF x primary battery in the wide temperature zone. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 is the conductivity diagram of the electrolyte in the application embodiment 1, the application embodiment 2, the comparative example 1 and the comparative example 2 at -40℃~60℃; Figure 2 is the conductivity diagram of the electrolyte in the application embodiment 1, the comparative example 1 and the comparative example 2 at -40℃~60℃;7 Li nuclear magnetic spectrum; Figure 3 Li / O-CF x Discharge curve of primary battery at-40℃ with different discharge rates; Figure 4 Li / O-CF x Discharge curve of primary battery at 60℃ with different discharge rates; Figure 5 Li / O-CF x Discharge curve of primary battery at-40℃-60℃ with 0.2C rate; Figure 6 Discharge curve of primary battery at-40℃ with different discharge rates prepared by example 1 and comparative example 3; Figure 7 Discharge curve of primary battery at-40℃ with 0.2C rate prepared by example 1, example 2, example 3 and example 4; Figure 8 TOF-SIMS 2D 3D spectrum of LiF and Li2CO3 content of the electrode sheet after discharge of the primary battery prepared by example 1 and comparative example 3; Figure 9 XPS spectrum of C 1s and O 1s of the electrode sheet after discharge of the primary battery prepared by example 1 and comparative example 3; Figure 10 XPS C1s and O1s spectrum of original CF x and O-CF x after mixed acid treatment. DETAILED DESCRIPTION

[0028] Embodiments of the present application are described in detail below, examples of which are shown in the accompanying drawings. The embodiments described below by reference to the drawings are examples and are intended to explain the present application, and are not to be understood as limiting the present application.

[0029] It should be noted that the terms "first", "second" are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. Further, in the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0030] In this document, the terms "containing", "including" or "comprising" are open expressions, i.e. including the contents indicated by the present application, but not excluding other aspects.

[0031] As used herein, the terms "optionally," "optionally," or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0032] After the positive electrode material of the present invention is modified with oxygen-containing functional groups of mixed acid, CF x When reacting with lithium, some of the Li will react with surface oxygen groups to form Li2CO3 instead of all forming LiF. Li2CO3 has higher lithium ion conductivity than LiF, indicating that the Li2CO3 layer can provide a better ion transport channel, effectively reducing internal resistance and polarization. In addition, the Li2CO3 film is relatively dense and has good compatibility with organic electrolytes. It can form a uniform and stable passivation layer on the cathode surface, inhibiting side reactions. Moreover, the introduction of the Li2CO3 product will reduce the accumulation of the LiF layer and accelerate the transfer rate of lithium ions and electrons. As a product with better conductivity, Li2CO3 can also effectively improve the discharge current capacity of the cathode and shorten the polarization time.

[0033] In addition, since 1,3-dioxolane (DOL) and methyl propionate (MP) in the electrolyte both have extremely low freezing points and low viscosity at low temperatures, they can significantly reduce the freezing point of the electrolyte, allowing the electrolyte of the present invention to remain liquid at extremely low temperatures, avoiding crystallization or phase separation, thereby ensuring that the battery can operate normally in cold environments. Secondly, since propylene carbonate (PC) has a high dielectric constant (ε=64), it helps the dissolution and dissociation of LiClO4 in the electrolyte, and Li + Usually it is surrounded by electrophilic groups in solvent molecules (such as C=O in PC, ether oxygen in DOL and ester oxygen in MP), forming a stable solvation structure, in which PC surrounds Li + The first layer of solvation structure is formed around the DOL and MP mixed solvent to form the second layer of solvation structure. This double-layer solvation system achieves a dynamic balance of ion-solvent interaction by adjusting the interaction between solvents and the overall dielectric constant, thereby optimizing the ion transport kinetics of the electrolyte. In addition, due to the large size and strong polarity of PC molecules, they can interact with Li during the charge and discharge process of the battery. + Collaborative Embedding CF x layer, forming Li x (PC) y The "solvated lithium" structure of the C6 complex. This co-intercalation expands the CF x The interlayer spacing is conducive to more complete discharge and further improves the capacity and rate performance of the battery.

[0034] With reference to the accompanying drawings on the drawings in the embodiments of the present application, the technical solutions in the embodiments of the present application are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the protection scope of the present application.

[0035] Embodiment 1 This embodiment provides a full-time, double-high Li / O-CF x The preparation method of the primary battery comprises the following steps: (1) Preparation of positive active material O-CF x : In the present application, the original CF x (purchased from Shandong Zhongshan Optoelectronic Material Co., Ltd.) is a fluorocarbon with a relatively low degree of fluorination, with a fluorocarbon element ratio of F:C = 0.6:1. The original fluorocarbon is dispersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, and is condensed and refluxed at 100℃ for 10h with continuous stirring during the refluxing process. After the reaction is completed, the reaction solution is washed and filtered, the residual acid in the reaction solution is removed, and the pH of the filtrate is adjusted to 7. After drying at 80℃ under vacuum, an oxygen-modified fluorocarbon material is obtained, i.e. O-CF x ; (2) Preparation of positive electrode sheet: 320mg of O-CF x , 80mg of conductive agent Super P (purchased from Sigma-Aldrich Co., Ltd.), and 80mg of 4wt.% PVDF binder (purchased from Aladdin Bio-Chem Technology Co., Ltd.) configured with NMP as the solvent are poured into a mortar and ground to obtain a uniform black paste. Then, a 50µm doctor blade is used to uniformly coat the paste on an aluminum foil, and the coated aluminum foil is dried at 60℃ for 24h to obtain a positive electrode sheet. (3) Li / O-CF x primary battery: In an argon glove box, a CR2025 button cell is assembled in the order of negative electrode shell, lithium metal sheet, first electrolyte layer, PP separator, second electrolyte layer, positive electrode sheet, gasket, spring, and positive electrode shell (the negative electrode shell, spring, and gasket are purchased from Keluode Co., Ltd., and the PP separator is purchased from Duodu Reagent Network), to obtain a primary battery in this example, which is marked as Li / O-CF x primary battery; The first electrolyte layer and the second electrolyte layer are the same and are obtained by the preparation method of the electrolyte, that is, 1.064 mg of LiClO4 is respectively dissolved in 10 ml of PC, 10 ml of DOL and 10 ml of MP, and stirred at 400 r / min until completely dissolved in an argon atmosphere glove box; then the above three solutions are mixed in a volume ratio of 1:1:12 and stirred at 400 r / min in an argon atmosphere glove box, to obtain the electrolyte, which is recorded as Li-PC / DOL / MP (1:1:12).

[0036] Example 2 This example provides a full-time, double-high Li / O-CF x The preparation method of the primary battery comprises the following steps: (1) Preparation of the positive active material O-CF x The original CF x (purchased from Shandong Zhongshan Optoelectronic Material Co., Ltd.) used in the present application is a fluorinated carbon with a relatively low degree of fluorination, and the fluorocarbon element ratio is F:C = 0.6:1. The original fluorinated carbon is dispersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 4:1, and is condensed and refluxed at 120°C for 8h with continuous stirring during the refluxing process. After the reaction is completed, the reaction solution is washed and filtered, the residual acid in the reaction solution is removed, and the pH of the filtrate is adjusted to 7. After vacuum drying at 80°C, the oxygen-modified fluorinated carbon material is obtained, that is, O-CF x ; (2) Preparation of the positive electrode sheet: 320 mg of O-CF x , 80 mg of conductive agent Super P (purchased from Sigma-Aldrich Co., Ltd.), and 80 mg of 4wt.% PVDF binder prepared by using NMP as the solvent (purchased from Aladdin Biochemical Technology Co., Ltd.) are poured into a mortar and ground to obtain a uniform black paste. Then, a 50 µm doctor blade is used to uniformly coat the paste on an aluminum foil, and the aluminum foil is dried at 60°C for 24 h to obtain the positive electrode sheet. (3) Li / O-CF x primary battery: in an argon glove box, a CR2025 type button cell is assembled in the order of negative electrode shell, lithium metal sheet, first electrolyte layer, PP separator, second electrolyte layer, positive electrode sheet, gasket, spring, and positive electrode shell (the positive and negative electrode shells and the spring and gasket are purchased from Keluode Co., Ltd., and the PP separator is purchased from Duodu Reagent Network), to obtain the primary battery in this example, which is marked as Li / O-CF x primary battery. The first electrolyte layer and the second electrolyte layer are the same and are obtained by the preparation method of the electrolyte, that is, 1.064 mg of LiClO4 is respectively dissolved in 10 ml of PC, 10 ml of DOL and 10 ml of MP, and stirred at 400 r / min until completely dissolved in an argon atmosphere glove box; then the above three solutions are mixed in a volume ratio of 1:1:1 and stirred at 400 r / min in an argon atmosphere glove box, to obtain the electrolyte, which is recorded as Li-PC / DOL / MP (1:1:1).

[0037] Example 3 This example provides a full-time, double-high Li / O-CF x The preparation method of the primary battery comprises the following steps: (1) Preparation of the positive active material O-CF x The original CF x (purchased from Shandong Zhongshan Optoelectronic Material Co., Ltd.) used in the present application is a fluorinated carbon with a relatively low degree of fluorination, and the fluorocarbon element ratio is F:C = 0.6:1. The original fluorinated carbon is dispersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 2:1, and is condensed and refluxed at 80°C for 12 h with continuous stirring during the refluxing process. After the reaction is completed, the reaction solution is washed and filtered, the residual acid in the reaction solution is removed, and the pH of the filtrate is adjusted to 7. After vacuum drying at 80°C, the oxygen-modified fluorinated carbon material is obtained, that is, O-CF x ; (2) Preparation of the positive electrode sheet: 320 mg of O-CF x , 80 mg of conductive agent Super P (purchased from Sigma-Aldrich Co., Ltd.), and 80 mg of 4wt.% PVDF binder prepared by using NMP as the solvent (purchased from Aladdin Biochemical Technology Co., Ltd.) are poured into a mortar and ground to obtain a uniform black paste. Then, a 50 µm doctor blade is used to uniformly coat the paste on an aluminum foil, and the aluminum foil is dried at 60°C for 24 h to obtain the positive electrode sheet. (3) Assembly of the Li / O-CF x primary battery: In an argon glove box, a CR2025 button cell is assembled in the order of negative electrode shell, lithium metal sheet, first electrolyte layer, PP separator, second electrolyte layer, positive electrode sheet, gasket, spring, and positive electrode shell (the positive and negative electrode shells and the spring and gasket are purchased from Keluode Co., Ltd., and the PP separator is purchased from Duodu Reagent Network), to obtain the primary battery in this example, which is marked as Li / O-CF x primary battery. The first electrolyte layer and the second electrolyte layer are the same and are obtained by the preparation method of the electrolyte, that is, 1.064 mg of LiClO4 is respectively dissolved in 10 ml of PC, 10 ml of DOL and 10 ml of MP, and stirred at 400 r / min until completely dissolved in an argon atmosphere glove box; then the above three solutions are mixed in a volume ratio of 1:1:4 and stirred at 400 r / min in an argon atmosphere glove box, to obtain the electrolyte, which is recorded as Li-PC / DOL / MP (1:1:4).

[0038] Example 4 This example provides a full-time, double-high Li / O-CF x The preparation method of the primary battery comprises the following steps: (1) Preparation of the positive active material O-CF x The raw CF x (purchased from Shandong Zhongshan Optoelectronic Material Co., Ltd.) used in the present application is a fluorinated carbon with a relatively low degree of fluorination, and the fluorocarbon element ratio is F:C = 0.6:1. The raw fluorinated carbon is dispersed in a mixed solution of concentrated sulfuric acid and concentrated nitric acid in a volume ratio of 3:1, and is condensed and refluxed at 100 ℃ for 12 h with continuous stirring during the refluxing process. After the reaction is completed, the reaction solution is washed and suction-filtered with pure water to remove the residual acid in the reaction solution until the pH of the filtrate is 7. After vacuum drying at 80 ℃, the oxygen-modified fluorinated carbon material is obtained, that is, O-CF x ; (2) Preparation of the positive electrode sheet: 320 mg of O-CF x , 80 mg of conductive agent Super P (purchased from Sigma-Aldrich Co., Ltd.), and 80 mg of 4wt.% PVDF binder configured with NMP as the solvent (purchased from Aladdin Biochemical Technology Co., Ltd.) are poured into a mortar and ground to obtain a uniform black paste. Then, a 50 µm doctor blade is used to uniformly coat the paste on an aluminum foil, and the aluminum foil is dried at 60 ℃ for 24 h to obtain the positive electrode sheet. (3) Li / O-CF x The primary battery is assembled in an argon glove box in the order of negative electrode shell, lithium metal sheet, first electrolyte layer, PP separator, second electrolyte layer, positive electrode sheet, gasket, spring, and positive electrode shell (the positive and negative electrode shells and the spring and gasket are purchased from Keluode Co., Ltd., and the PP separator is purchased from Duodu Reagent Network), to obtain a CR2025 type button cell, that is, the primary battery in this example, which is marked as Li / O-CF x primary battery. The first electrolyte layer and the second electrolyte layer are the same and obtained by the preparation method of the electrolyte, that is, 1.064 mg of LiClO4 is respectively dissolved in 10 ml of PC, 10 ml of DOL and 10 ml of MP, and stirred at 400 r / min in an argon atmosphere glove box until completely dissolved; then the above three solutions are mixed in a volume ratio of 1:1:16 and stirred at 400 r / min in an argon atmosphere glove box, to obtain the electrolyte, which is recorded as Li-PC / DOL / MP (1:1:16).

[0039] Comparative Example 1 The present comparative example provides a preparation method of a common Li / O-CF x battery. The present comparative example is different from Example 1 only in that the first electrolyte layer and the second electrolyte layer both use a commercial electrolyte HR-6002 (purchased from Jiangxi Haicun New Material Co., Ltd.), and the rest are the same, which is recorded as Li-COE.

[0040] Comparative Example 2 The present comparative example provides a preparation method of a common Li / O-CF x battery. The present comparative example is different from Example 1 only in that the first electrolyte layer and the second electrolyte layer both use LX-478 electrolyte (purchased from Duoduoreagent network), wherein the ratio of the electrolyte is that 1 mol / L of lithium perchlorate (LiClO4) is dissolved in ethylene glycol dimethyl ether (DME), 1,3-dioxolane (DOL) and propylene carbonate (PC) in a volume ratio of 1:1:1, and the rest are the same, which is recorded as Li-LX-478.

[0041] Comparative Example 3 The present comparative example provides a preparation method of a common Li / CF x battery. The present comparative example is different from Example 1 only in that the positive active material is not modified by oxygen, and the original carbon fluoride (fluorocarbon element ratio F:C = 0.6:1) is used, and the rest are the same, which is recorded as Li / CF x primary battery.

[0042] Comparative Example 4 The present comparative example provides a preparation method of a common Li / O-CF x battery. The present comparative example is different from Example 1 only in that the preparation process of the positive active material O-CF x in the present comparative example is that the condensation reflux temperature is 60°C and the time is 6h, and the rest are the same.

[0043] Comparative Example 5 The present comparative example provides a preparation method of a common Li / O-CF x battery. The present comparative example is different from Example 1 only in that the preparation process of the positive active material O-CFx The temperature of the condensation reflux in the preparation process of the O-CF is 60℃, and the time is 12h, and the rest is the same.

[0044] Comparative Example 6 This comparative example provides a common Li / O-CF x battery preparation method. The difference between this comparative example and Example 1 is only that the temperature of the condensation reflux in the preparation process of the positive active material O-CF x is 100℃, and the time is 6h, and the rest is the same.

[0045] In order to verify the conductivity of the electrolyte in a wide temperature range, and the discharge performance and stability of the Li / O-CF x primary battery at different temperatures and discharge rates, and to explore the influence mechanism of material composition and processing technology on the performance of the battery, a series of experimental studies of the examples and comparative examples were carried out.

[0046] Firstly, the conductivity of the three electrolytes prepared in Example 1, Example 2, Comparative Example 1 and Comparative Example 2 was tested at-40℃ to 60℃ (using a De Ding Sheng JY-82C conductivity meter), as shown in Figure 1 , the conductivity of the electrolyte of Example 1 and Example 2 at 60℃ is less than that of Comparative Example 1 and Comparative Example 2, and the conductivity at room temperature and low temperature is greater than that of Comparative Example 1 and Comparative Example 2, which shows that it has obvious advantages at low temperature.

[0047] Then, the capacity of the primary battery of Example 1 was tested at-40℃ and 60℃ under different discharge rates (using a Lan electric battery test system), as shown in Figure 3 and Figure 4 The results show that at-40℃, the voltage platform is about 2V at a discharge rate of 0.2C, and the capacity can reach 715mAh / g, the voltage platform is about 1.8V at a discharge rate of 0.5C, and the capacity can reach 466mAh / g, which is 82.66% of the capacity at room temperature, the energy density is 1385.68 Wh / kg, and the power density is 336.3 W / kg; at 60℃, the voltage platform is about 2.6V at a discharge rate of 0.2C, and the capacity is 850mAh / g, the voltage platform is about 2.4V at a discharge rate of 0.5C, and the capacity is 760mAh / g, which is 98.2% of the capacity at room temperature, the energy density is 2079.07 Wh / kg, and the power density is 424.3 W / kg. Figure 5 It also shows the performance of the primary battery at different temperatures, which shows that the Li / O-CF x primary battery of the application exhibits excellent performance at a discharge rate of 0.2C and 0.5C in a wide temperature range of-40℃ to 60℃.

[0048] Li / CF x The discharge capacity of the primary battery at -40℃ was tested at different discharge rates, and the results are shown in Table 1. Figure 6 Li / O-CF x The low-temperature discharge capacity of the primary battery was significantly improved, indicating that the oxygen modification step was crucial. In addition, by comparing Examples 1-4, it was found that methyl propionate (MP) played a key role in low-temperature discharge, and its content had a first-increasing-then-decreasing relationship with battery performance, with Li-PC / DOL / MP (1:1:12) being preferred. Figure 7

[0049] At the same time, analysis of the battery electrode further revealed the reasons for the performance improvement. From the TOF-SIMS 2D and 3D maps, Figure 8 it can be seen that the O-CF x material after acid treatment generated more Li2CO3 on the electrode after discharge, replacing LiF, thereby improving the discharge performance. XPS spectra Figure 9 analysis showed that the peak near 280eV in C 1s was some product containing Li, and the increase in Li-containing products and the decrease in C-related peaks in the electrode after discharge of Example 1 proved that the O-CF x reaction was more complete; the peak near 532eV in O 1s was Li2CO3, and the increase in content could be seen, and from Figure 10 it can be seen that the original CF x after mixed acid treatment, O 1s showed an increase in oxygen-containing functional groups, which may be an important factor in the performance improvement.

[0050] Comparative Examples 4-6 were to explore the optimal choice of acidification temperature and time. The capacity of the primary battery of Comparative Examples 4-6 was tested at different discharge rates at -40℃ (using a Bluecell battery test system), and the results are shown in Table 1. The performance of Comparative Example 4 was 432 mAh / g at 0.2C and 276 mAh / g at 0.5C; the performance of Comparative Example 5 was 576 mAh / g at 0.2C and 368 mAh / g at 0.5C; and the performance of Comparative Example 6 was 612 mAh / g at 0.2C and 391 mAh / g at 0.5C. The results showed that when the acidification temperature was too low or the time was too short, the reaction was not complete and the conversion rate was low, resulting in insufficient performance.

[0051] For the Li / O-CF x primary battery prepared in Example 1, the effect comparison with other literature in the art is shown in Table 1.

[0052] Table 1 Effect comparison of the primary battery prepared in Example 1 with other literature ​

[0053] Based on the above research, the present application solves the technical problems of high melting point and high viscosity of the conventional Li / CF x The primary battery electrolyte has high melting point, high viscosity, slow ion transmission kinetics at low temperature, high electrode / electrolyte interface resistance and other technical problems, and the Li / CF x The primary battery has high energy density and high power density.

[0054] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An all-weather, dual-high type lithium / carbon fluoride battery, characterized in that: It includes the following components: surface oxygen modified CF x Positive electrode material and electrolyte, wherein the surface oxygen-modified CF x The positive electrode material is original CF x The positive electrode material is obtained by mixed acid pretreatment.

2. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 1, characterized in that: The mixed acid includes a mixed solution prepared from concentrated sulfuric acid and concentrated nitric acid.

3. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 1, characterized in that: The components of the electrolyte include lithium salt, cyclic carbonate solvent, linear carboxylate solvent and ether solvent.

4. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 1, characterized in that: The surface oxygen modified CF x The preparation method of the positive electrode material comprises the following steps: A1. Convert the original CF x The positive electrode material is dispersed in the mixed acid solution, kept stirred and condensed under reflux; A2. The liquid after the reaction was shaken, washed and filtered, and then vacuum dried to obtain surface oxygen-modified CF x positive electrode material.

5. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 4, characterized in that: The mixed acid is prepared from concentrated sulfuric acid and concentrated nitric acid in a volume ratio of (2-4):

1. The temperature of the condensation reflux is 80-120° C., and the time is 8-12 hours.

6. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 3, characterized in that: Among the components of the electrolyte, the volume ratio of the cyclic carbonate solvent, the ether solvent and the linear carboxylate solvent is 1:1:(1-16).

7. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 3, characterized in that: The cyclic carbonate solvent includes one or more of ethylene carbonate, propylene carbonate, and vinylene carbonate; the linear carboxylate solvent includes one or more of methyl formate, methyl acetate, methyl butyrate, and methyl propionate; and the ether solvent includes one or more of tetrahydrofuran, 2-methyltetrahydrofuran, 1,3-dioxolane, and 4-methyl-1,3-dioxolane.

8. The all-weather, dual-high type lithium / carbon fluoride battery according to claim 1, characterized in that: The preparation method of the electrolyte comprises the following steps: B1. Dissolve the lithium salt in a cyclic carbonate solvent, a linear carboxylate solvent, and an ether solvent, respectively, and stir in an argon atmosphere glove box until completely dissolved; B2. The three solutions were mixed and stirred in an argon atmosphere glove box to obtain the electrolyte.

9. A method for preparing an all-weather, dual-high lithium / carbon fluoride battery according to any one of claims 1 to 8, comprising the following steps: S1, CF modified with surface oxygen x The positive electrode material, conductive agent and binder are ground and mixed, and then the binder is added and further ground to obtain a uniform black slurry, which is then applied to aluminum foil and dried to obtain a positive electrode sheet; S2. In an argon atmosphere glove box, a button cell is assembled in the order of a negative electrode shell, a lithium metal sheet, a first electrolyte layer, a polypropylene separator, a second electrolyte layer, a positive electrode sheet, a gasket, a spring, and a positive electrode shell to obtain the battery.

10. Use of the all-weather, dual-high lithium / carbon fluoride battery according to any one of claims 1 to 8 in the field of lithium primary batteries.

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