Gel electrolyte composition, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present invention relates to a gel electrolyte composition, a secondary battery, a battery module, a battery pack, and a power consumption device. The gel electrolyte composition has a viscosity of 500 mPa·s to 100,000 mPa·s at 25°C. Having the gel electrolyte composition in an appropriate viscosity range can increase the interfacial wettability of the battery, contributing to increasing the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures, while also weakening interfacial side reactions of the gel electrolyte composition and increasing the coulombic efficiency of the battery.

Description

[Technical Field]

[0001] The present application relates to the technical field of secondary batteries, and in particular to gel electrolyte compositions, secondary batteries, battery modules, battery packs, and power consuming devices. [Background technology]

[0002] In recent years, secondary batteries have been widely applied in energy storage power supply systems such as hydroelectric, thermal, wind and solar power plants, as well as in many fields such as power tools, electric bicycles, electric motorcycles, electric vehicles, military equipment, aerospace, etc. As the use of secondary batteries becomes more widespread, higher requirements are being placed on their performance and safety.

[0003] Currently, most batteries use liquid electrolytes, but liquid electrolytes are prone to side reactions with metal negative electrodes, resulting in reduced battery performance and increased safety risks. Liquid electrolytes are also prone to the formation of dendrites on the negative electrodes during cycling, leading to battery short circuits and, in severe cases, battery explosions, making them unable to meet the needs of new-generation electrochemical systems. Summary of the Invention

[0004] The present application has been made in view of the above-mentioned problems, and aims to provide a gel electrolyte composition, which combines the fluidity of a liquid electrolyte with the safety and reliability of an all-solid-state electrolyte, thereby improving the safety performance of a battery and, at the same time, taking into account the dynamic performance of the battery, improving the overall performance of the battery.

[0005] A first aspect of the present application provides a gel electrolyte composition having a viscosity at 25°C of 500 mPa·s to 100,000 mPa·s.

[0006] When a gel electrolyte composition has an appropriate viscosity range, it can provide ion transport channels and improve the ionic conductivity, as well as have high safety performance, reduce gas generation in batteries, especially at high temperatures, and enhance battery safety, thereby fully utilizing the advantages of liquid electrolytes and all-solid-state electrolytes. When a gel electrolyte composition has an appropriate viscosity range, it can increase the interfacial wettability of batteries, contributing to enhancing the interfacial dynamics process of the gel electrolyte composition at room temperature and high temperatures, while weakening interfacial side reactions of the gel electrolyte composition, helping to increase the Coulomb efficiency of batteries, especially at high temperatures.

[0007] In any embodiment, the gel electrolyte composition includes a solvent, and the ratio of the amount of free solvent material to the total amount of solvent material in the gel electrolyte composition is based on the total amount of the solvent material. JPEG2025534035000002.jpg6150.

[0008] Controlling the ratio of the amount of free solvent material to the total amount of solvent material in the gel electrolyte composition can ensure that the gel electrolyte composition has high ionic conductivity, excellent interfacial dynamics process and mass transfer process, and contribute to increasing the ionic conductivity of the gel electrolyte composition at room temperature and high temperature. At the same time, it can also avoid an excessively high ratio of the amount of free solvent material, which increases the amount of gas generated, leads to an increase in the expansion rate of the battery, and reduces the safety of the battery.

[0009] In any embodiment, the mass content of the solvent is 20% to 75% based on the total mass of the gel electrolyte composition.

[0010] By controlling the mass content of the solvent to be 20% to 75% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0011] In any embodiment, the gel electrolyte composition further comprises an electrolyte salt, and the mass content of the electrolyte salt is 5% to 70% based on the total mass of the gel electrolyte composition.

[0012] By controlling the mass content of the electrolyte salt to be 5% to 70% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0013] In any embodiment, the gel electrolyte composition further comprises a polymer, and the mass content of the polymer is 2% to 20% based on the total mass of the gel electrolyte composition.

[0014] By controlling the polymer mass content to be 2% to 20% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0015] In any embodiment, the gel electrolyte composition is a supersaturated gel electrolyte composition at 25°C.

[0016] In any embodiment, the supersaturated gel electrolyte composition has a viscosity at 25°C of 3000 mPa·s to 100000 mPa·s and a viscosity at 60°C of 500 mPa·s to 5000 mPa·s.

[0017] In any embodiment, the supersaturated gel electrolyte composition has a viscosity at 25°C of 3000 mPa·s to 11000 mPa·s and a viscosity at 60°C of 500 mPa·s to 3000 mPa·s.

[0018] The supersaturated gel electrolyte composition having an appropriate viscosity range contributes to increasing the ionic conductivity of the gel electrolyte composition at room temperature and at high temperatures, and also to increasing the coulombic efficiency of the battery at 60°C, thereby expanding the temperature range in which the battery can be used.

[0019] In any embodiment, the supersaturated gel electrolyte composition comprises a dissolved electrolyte salt and a precipitated, crystallized electrolyte salt.

[0020] The precipitated and crystallized electrolyte salt is uniformly dispersed in the supersaturated gel electrolyte composition system, further reinforcing the mechanical performance of the supersaturated gel electrolyte composition.

[0021] In any embodiment, the median particle size of the precipitated and crystallized electrolyte salt is 100 μm or less.

[0022] By controlling the median particle size of the precipitated and crystallized electrolyte salt to 100 μm or less, it is possible to avoid particles that are too large and inhibit the transmission of ions.

[0023] In any embodiment, based on the total mass of the supersaturated gel electrolyte composition, the mass content of the electrolyte salt is 30% to 70%, the mass content of the solvent is 20% to 60%, and the mass content of the polymer is 2% to 20%.

[0024] By controlling the mass content of the electrolyte salt to 30% to 70%, the mass content of the solvent to 20% to 60%, and the mass content of the polymer to 2% to 20%, based on the total mass of the supersaturated gel electrolyte composition, the ionic conductivity of the supersaturated gel electrolyte composition at room temperature and high temperatures can be increased, and the coulombic efficiency of the battery at 60°C can be improved.

[0025] In any embodiment, the electrolyte salt comprises a sodium salt, the sodium salt comprising one or more of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium yttrium fluoride, sodium hexafluoroarsenate, sodium tetraphenylborate, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium (n-nonafluorobutanesulfonyl)imide, and optionally one or more of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide.

[0026] All of the above sodium salts contribute to increasing the coulombic efficiency of the battery at 60° C. and 80° C., thereby improving battery performance. When the sodium salt includes one or more of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide, the coulombic efficiency of the battery at 60° C. can be further increased, and the cycle performance of the battery at 25° C. and 60° C. can be improved, thereby significantly improving battery performance.

[0027] In any embodiment, the solvent comprises one or more of an ether organic solvent, an ester organic solvent, or a sulfur-containing organic solvent, including one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, γ-butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide, and optionally one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane.

[0028] All of the above solvents contribute to increasing the coulombic efficiency of the battery at 60° C. When the solvent is selected from one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane, the coulombic efficiency of the battery at room temperature and high temperature can be further increased, the cycle performance of the battery at 25° C. and 60° C. can be improved, and the thickness expansion rate of the battery at 25° C. and 60° C. can be reduced, thereby significantly improving the performance and safety of the battery.

[0029] In any embodiment, the polymer comprises one or more of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, perfluoropolyether, poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, optionally comprising one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

[0030] Any of the above polymers contributes to increasing the coulombic efficiency of the battery at 25° C. and 60° C., and to increasing the number of cycles until the capacity retention rate of the battery reaches 80% at 60° C. When the polymer is selected from one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, the thickness expansion rate of the battery at 25° C. can be further reduced, the amount of gas generation can be reduced, and the safety of the battery can be significantly improved.

[0031] In any embodiment, the electrolyte salt comprises one or more of sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide; the solvent comprises one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane; and the polymer comprises one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

[0032] The gel electrolyte composition can provide both electrical performance and safety for the battery.

[0033] A second aspect of the present application provides a secondary battery including a positive electrode plate and the gel electrolyte composition described in any embodiment.

[0034] This secondary battery has excellent cycle performance.

[0035] In any embodiment, the secondary battery includes at least one of a lithium battery and a sodium battery.

[0036] In any embodiment, the secondary battery is a negative electrode-free sodium battery, which can have a high energy density.

[0037] In any embodiment, the CB value of the negative electrode-free sodium battery is 0.1 or less.

[0038] In any embodiment, the positive electrode plate includes a positive electrode active material, the positive electrode active material including at least one of a transition metal layered oxide, a polyanion compound, and a Prussian blue compound, and NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 )O2, Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 O2, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3, Na 1.9 CoFe(CN)6, Na2NiFe(CN)6, NaMnFe(CN)6.

[0039] Any of the above positive electrode active materials can provide the battery with excellent electrical performance.

[0040] In any embodiment, a coating layer is provided on a surface of the positive electrode active material, and the coating layer includes one or more of a carbon material, ZrO, TiO, polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene), aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, magnesium oxide, silicon oxide, lanthanum oxide, sodium fluoride, lithium fluoride, and aluminum fluoride, and the carbon material includes one or more of amorphous carbon, graphite, and graphene.

[0041] The coating layer on the surface of the positive electrode active material increases the coulombic efficiency of the battery at room temperature and high temperatures, improves the cycle performance of the battery at 25°C, and reduces the thickness expansion rate of the battery at 25°C and 60°C, further contributing to reducing the amount of gas generation, thereby significantly improving the performance and safety of the battery.

[0042] A third aspect of the present application provides a battery module including the secondary battery according to the second aspect of the present application.

[0043] A fourth aspect of the present application provides a battery pack including the secondary battery according to the second aspect of the present application or the battery module according to the third aspect of the present application.

[0044] A fifth aspect of the present application provides a power consumption device including at least one of the secondary battery according to the second aspect of the present application, the battery module according to the third aspect of the present application, and the battery pack according to the fourth aspect of the present application. [Brief explanation of the drawings]

[0045] [Figure 1] 1 is a schematic diagram of a secondary battery according to an embodiment of the present application; [Figure 2] FIG. 2 is an exploded view of the secondary battery according to the embodiment of the present application shown in FIG. [Figure 3] 1 is a schematic diagram of a battery module according to an embodiment of the present application; [Figure 4] 1 is a schematic diagram of a battery pack according to an embodiment of the present application. [Figure 5] FIG. 5 is an exploded view of the battery pack shown in FIG. 4 according to an embodiment of the present application. [Figure 6] 1 is a schematic diagram of a power consuming device that uses a secondary battery as a power source according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0046] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the gel electrolyte composition, secondary battery, battery module, battery pack, and electrical device of the present application will be described in detail. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and redundant descriptions of substantially the same structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate easy understanding by those skilled in the art. Furthermore, the drawings and the following description are provided to enable those skilled in the art to fully understand the present application and are not intended to limit the scope of the claims.

[0047] The "ranges" disclosed herein are defined in the form of lower and upper limits. A given range is defined by selecting one lower limit and one upper limit, and the selected lower and upper limits define the boundaries of the particular range. Such defined ranges may be inclusive or exclusive of the endpoints and may be arbitrarily combined; i.e., any lower limit may be combined with any upper limit to form a single range. For example, if ranges of 60 to 120 and 80 to 110 are recited for a given parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also contemplated. Furthermore, if 1 and 2 are recited as minimum range values ​​and 3, 4, and 5 are recited as maximum range values, then the ranges of 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all contemplated. Unless otherwise specified herein, a numerical range "a to b" represents a shorthand notation for any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0 to 5" means that all real numbers between "0 and 5" are listed herein, and "0 to 5" is simply shorthand for combinations of these numbers. Note that describing a parameter as an integer ≧2 is equivalent to disclosing that the parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0048] Unless otherwise stated, all embodiments and alternative embodiments in the present application can be combined with each other to form new technical solutions.

[0049] Unless otherwise stated, all technical features and optional technical features of the present application can be combined with each other to form new technical solutions.

[0050] Unless otherwise specified, all steps herein may be performed in sequence or randomly, preferably in sequence. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in sequence, or may include steps (b) and (a) performed in sequence. For example, when it is stated that the method may further include step (c), it means that step (c) can be added to the method in any order; for example, the method may include steps (a), (b), and (c), or may include steps (a), (c), and (b), or may include steps (c), (a), and (b).

[0051] Unless otherwise specified, the terms "comprise" and "comprises" used herein may be open-ended or closed-ended. For example, the terms "comprise" and "comprises" may indicate that the compound may further include or include other components not listed, or may include or include only the listed components.

[0052] Unless otherwise stated, the term "or" in this application is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any one of the following conditions satisfies the condition "A or B": A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or A and B are both true (or exist).

[0053] Currently, liquid electrolytes have many problems. Solid-state electrolytes have attracted the attention of researchers because they can effectively suppress side reactions at the metal anode interface and the associated safety issues caused by dendrites. However, most solid-state electrolytes have difficulty forming good interfacial contact with the electrode plate, which affects the electrolyte's ionic conductivity and interfacial dynamics, reducing the battery's power efficiency. Therefore, it is necessary to develop a new electrolyte system that can balance the electrochemical performance and safety of batteries.

[0054] [Gel electrolyte composition] Based on this, the present application proposes a gel electrolyte composition, which has a viscosity at 25°C of 500 mPa·s to 100,000 mPa·s.

[0055] In this specification, a gel electrolyte composition refers to an electrolyte composition that not only has the fluidity of a liquid electrolyte but also has the mechanical strength of an all-solid electrolyte.

[0056] In some embodiments, the gel electrolyte composition has a viscosity at 25° C. of optionally 500 mPa·s, 1000 mPa·s, 2000 mPa·s, 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 20000 mPa·s, 30000 mPa·s, 40000 mPa·s, 50000 mPa·s, 60000 mPa·s, 70000 mPa·s, 80000 mPa·s, 90000 mPa·s, or 100000 mPa·s.

[0057] In this specification, the viscosity of the gel electrolyte composition can be tested using a method known in the art, for example, a rotational viscometer is used to measure the viscosity of the slurry. An appropriate rotor is selected, the rotor of the viscometer is fixed, and the slurry is placed under the rotor of the viscometer so that the slurry is just immersed in the rotor's graduation lines. The instrument model is Shanghai Fangrui NDJ-5S, the rotor is 63# (2000-10000 mPa.s) or 64# (10000-50000 mPa.s), the rotation speed is 12 rpm, the test time is 5 minutes, and the data is read after the reading becomes stable.

[0058] When a gel electrolyte composition has an appropriate viscosity range, it can provide ion transport channels and improve the ionic conductivity, and it also has high safety and can avoid the generation of large amounts of gas in the solvent of the electrolyte composition, thereby improving the safety of the battery and fully utilizing the advantages of liquid electrolytes and all-solid-state electrolytes. When a gel electrolyte composition has an appropriate viscosity range, it can increase the interfacial wettability of the battery, contributing to improving the interfacial dynamics of the gel electrolyte composition at room temperature and high temperatures, while weakening the interfacial side reactions of the gel electrolyte composition, which is useful for improving the Coulombic efficiency of the battery, especially at high temperatures.

[0059] In this specification, the term "room temperature" refers to a temperature between 5°C and 35°C.

[0060] In this specification, the term "high temperature" refers to 40°C to 80°C.

[0061] In this specification, the coulombic efficiency refers to the average coulombic efficiency, which is mainly used to characterize the average ratio of the battery discharge capacity to the charge capacity during the cycle process, and can reflect the degree of consumption of metal ions, and can be tested by any known method.

[0062] In this specification, ionic conductivity is mainly used to characterize the ion transfer ability of a gel electrolyte composition, can reflect the ion transfer ability of a gel electrolyte composition, and can be tested by any known method.

[0063] In some embodiments, the gel electrolyte composition includes a solvent, and the ratio of the amount of material that is free solvent to the total amount of solvent material in the gel electrolyte composition is based on the total amount of solvent material. In some embodiments, the ratio n of the amount of free solvent material to the total amount of solvent material in the gel electrolyte composition is based on the total amount of solvent material. FS is optionally 1%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65% or 70%.

[0064] In this specification, the ratio of the amount of free solvent to the total amount of solvent in a gel electrolyte composition can be determined by methods known in the art. For example, a Nicolet iS5 Fourier transform infrared spectrophotometer is used to examine the infrared spectrum of the gel electrolyte composition. After normalization of the spectrogram, the intensity of the characteristic peak of the solvent is recorded as I1. The solvent of the gel electrolyte composition is used as a reference sample, and its infrared spectrum is measured. After normalization of the spectrogram, the intensity of the characteristic peak of the solvent is recorded as I2. I1 / I2 is the ratio of the amount of free solvent to the total amount of solvent in the gel electrolyte composition. The characteristic peak of the solvent is selected depending on the type of solvent. For ether solvents, the characteristic peak of CO is between 800 and 900 cm. -1 In the case of ester solvents, the characteristic peak of C=O is located between 850 and 950 cm -1 Between 1700 and 1800 cm -1 As used herein, the term "solvent" refers to any liquid capable of dissolving a solid, liquid, or gaseous solute. Solvents include free solvents and non-free solvents.

[0065] As used herein, the term "free solvent" refers to solvent molecules that are not coordinated with anions or cations, that have no hydrogen bonding or hydrogen bond-like interactions between the solvent and the solvent molecules, and that can move freely. For example, a free solvent is not involved in the solvation structure of an electrolyte salt, is not coordinated with anions or cations of the electrolyte salt, is not involved in swelling of a polymer, and does not have strong bonding effects with other functional groups.

[0066] As used herein, the term "non-free solvent" refers to solvent molecules that are coordinated with anions or cations, or that have hydrogen bonding or hydrogen-bond-like interactions between the solvent and the solvent molecules, preventing them from moving freely. Controlling the ratio of the amount of free solvent material to the total amount of solvent material in a gel electrolyte composition can ensure that the gel electrolyte composition has high ionic conductivity, excellent interfacial dynamics, and mass transfer processes, contributing to increasing the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures. At the same time, it can also avoid an excessively high ratio of free solvent material, which can increase gas generation, increase the battery swelling rate, and reduce battery safety.

[0067] In some embodiments, the solvent content is 20% to 75% by weight, optionally 20%, 22%, 25%, 30%, 35%, 38%, 40%, 45%, 47%, 50%, 53%, 55%, 60%, 62%, 65%, 70%, or 75% by weight, based on the total weight of the gel electrolyte composition.

[0068] By controlling the mass content of the solvent to be 20% to 75% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0069] In some embodiments, the gel electrolyte composition further comprises an electrolyte salt, and the mass content of the electrolyte salt is 5% to 70% based on the total mass of the gel electrolyte composition. In some embodiments, the mass content of the electrolyte salt is optionally 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70% based on the total mass of the gel electrolyte composition.

[0070] By controlling the mass content of the electrolyte salt to be 5% to 70% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0071] In some embodiments, the gel electrolyte composition further comprises a polymer, and the polymer content is 2% to 20% by weight based on the total weight of the gel electrolyte composition, or alternatively 2%, 4%, 5%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, or 20% by weight based on the total weight of the gel electrolyte composition.

[0072] By controlling the polymer mass content to be 2% to 20% based on the total mass of the gel electrolyte composition, the ionic conductivity of the gel electrolyte composition at room temperature and high temperatures is increased, which contributes to improving the coulombic efficiency of the battery at room temperature and high temperatures and the cycle performance at room temperature, thereby expanding the temperature range in which the battery can be used.

[0073] In some embodiments, the gel electrolyte composition is a supersaturated gel electrolyte composition at 25°C.

[0074] A supersaturated gel electrolyte composition refers to a gel electrolyte composition in which the electrolyte salt dissolved in the gel electrolyte composition exceeds the saturation concentration at room temperature (5°C to 30°C), causing some of the electrolyte salt to precipitate.

[0075] Compared to other gel electrolyte compositions, supersaturated gel electrolyte compositions have a higher electrolyte salt concentration. As the temperature increases, the electrolyte salt particles precipitated from the supersaturated gel electrolyte composition further dissolve, resulting in a more stable battery system. Furthermore, the supersaturated state of the supersaturated gel electrolyte composition can change the morphology of the electrolyte salt solvation structure, which also helps improve the chemical stability of the battery at high temperatures. In summary, supersaturated gel electrolyte compositions can improve the coulombic efficiency and cycle performance of batteries at high temperatures, reduce the amount of gas generation at high temperatures, and simultaneously improve the electrochemical and safety performance of batteries at high temperatures.

[0076] In some embodiments, the supersaturated gel electrolyte composition has a viscosity at 25°C of 3000 mPa·s to 100000 mPa·s and a viscosity at 60°C of 500 mPa·s to 5000 mPa·s.

[0077] In some embodiments, the supersaturated gel electrolyte composition has a viscosity at 25°C of 3000 mPa·s to 11000 mPa·s and a viscosity at 60°C of 500 mPa·s to 3000 mPa·s.

[0078] In some embodiments, the viscosity of the supersaturated gel electrolyte composition at 25° C. is optionally 3000 mPa·s, 4000 mPa·s, 5000 mPa·s, 6000 mPa·s, 7000 mPa·s, 8000 mPa·s, 9000 mPa·s, 10000 mPa·s, 20000 mPa·s, 30000 mPa·s, 40000 mPa·s, 50000 mPa·s, or 60000 mPa·s. , 70,000 mPa·s, 80,000 mPa·s, 90,000 mPa·s or 100,000 mPa·s, and the viscosity of the supersaturated gel electrolyte composition at 60°C is selectively 500 mPa·s, 600 mPa·s, 700 mPa·s, 800 mPa·s, 900 mPa·s, 1000 mPa·s, 1500 mPa·s, 2000 mPa·s, 2500 mPa·s or 3000 mPa·s.

[0079] The supersaturated gel electrolyte composition having an appropriate viscosity range contributes to increasing the ionic conductivity of the supersaturated gel electrolyte composition at room temperature and at high temperatures, and also to increasing the coulombic efficiency of the battery at 60°C, thereby expanding the temperature range in which the battery can be used.

[0080] In some embodiments, the supersaturated gel electrolyte composition comprises dissolved electrolyte salt and precipitated and crystallized electrolyte salt.

[0081] In this specification, the term "electrolyte salt that has precipitated and crystallized" refers to a state in which the concentration of the electrolyte salt exceeds the saturation concentration and a portion of the electrolyte salt is precipitated in the form of solid crystals.

[0082] The precipitated and crystallized electrolyte salt is dispersed uniformly as a dispersed phase in the continuous phase of the supersaturated gel electrolyte composition, further reinforcing the mechanical performance of the supersaturated gel electrolyte composition.

[0083] In some embodiments, the median particle size of the precipitated and crystallized electrolyte salt is 100 μm or less, optionally 1 μm, 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, or 100 μm.

[0084] Testing the median particle size of precipitated and crystallized electrolyte salts can be performed using methods known in the art. For example, centrifugal sedimentation and a laser particle size analyzer are used. The sample is first centrifuged, sedimented, and filtered to obtain the precipitated and crystallized electrolyte salt. Then, 0.1 g to 0.13 g of the precipitated and crystallized electrolyte salt sample to be tested is weighed into a 50 mL beaker, 5 g of acetone is added, a 2.5 mm stir bar is inserted, and the beaker is sealed with plastic wrap. The sample is sonicated for 5 minutes, then transferred to a magnetic stirrer and stirred at 500 rpm for at least 20 minutes. Two samples are extracted from each lot and tested. A Mastersizer 2000E laser particle size analyzer from Malvern Instruments, UK, is used for testing.

[0085] By controlling the median particle size of the precipitated and crystallized electrolyte salt to 100 μm or less, it is possible to avoid sedimentation of the precipitated and crystallized electrolyte salt and further to uniformly disperse it in the supersaturated gel electrolyte composition, while at the same time reinforcing the mechanical properties of the supersaturated gel electrolyte composition and also to avoid the particles being too large to inhibit ion transport.

[0086] In some embodiments, the weight content of the electrolyte salt is 30% to 70%, the weight content of the solvent is 20% to 60%, and the weight content of the polymer is 2% to 20%, based on the total weight of the supersaturated gel electrolyte composition. In some embodiments, the weight content of the electrolyte salt is optionally 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, or 70%, the weight content of the solvent is optionally 20%, 22%, 25%, 27%, 30%, 32%, 35%, 38%, 40%, 45%, 47%, 50%, 53%, 55%, 57%, or 60%, and the weight content of the polymer is optionally 2%, 4%, 5%, 8%, 10%, 12%, 14%, 15%, 16%, 18%, or 20%, based on the total weight of the supersaturated gel electrolyte composition.

[0087] By controlling the mass content of the electrolyte salt to 30% to 70%, the mass content of the solvent to 20% to 60%, and the mass content of the polymer to 2% to 20%, based on the total mass of the supersaturated gel electrolyte composition, the ionic conductivity of the supersaturated gel electrolyte composition at room temperature and high temperatures can be increased, and the coulombic efficiency of the battery at 60°C can be improved.

[0088] In some embodiments, the electrolyte salt comprises a sodium salt, which may include one or more of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium yttrium fluoride, sodium hexafluoroarsenate, sodium tetraphenylborate, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, sodium (n-nonafluorobutanesulfonyl)imide, and optionally one or more of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide.

[0089] In some embodiments, the sodium salt includes sodium chloride. In some embodiments, the sodium salt includes sodium bromide. In some embodiments, the sodium salt includes sodium hexafluorophosphate. In some embodiments, the sodium salt includes sodium tetrafluoroborate. In some embodiments, the sodium salt includes sodium trifluoromethanesulfonate. In some embodiments, the sodium salt includes sodium bis(fluorosulfonyl)imide. In some embodiments, the sodium salt includes sodium bis(fluorosulfonyl)imide and sodium bis(trifluoromethanesulfonyl)imide. In some embodiments, the sodium salt includes sodium tetrafluoroborate and sodium bis(fluorosulfonyl)imide.

[0090] All of the above sodium salts contribute to increasing the coulombic efficiency of the battery at 60° C. and 80° C., thereby improving battery performance. When the sodium salt includes one or more of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide, the coulombic efficiency of the battery at 60° C. can be further increased, and the cycle performance of the battery at 25° C. and 60° C. can be improved, thereby significantly improving battery performance.

[0091] In some embodiments, the solvent comprises one or more of an ether organic solvent, an ester organic solvent, or a sulfur-containing organic solvent, including one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, γ-butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide, optionally including one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane.

[0092] In some embodiments, the solvent comprises ethylene glycol dimethyl ether. In some embodiments, the solvent comprises diethylene glycol dimethyl ether. In some embodiments, the solvent comprises triethylene glycol dimethyl ether. In some embodiments, the solvent comprises tetraethylene glycol dimethyl ether. In some embodiments, the solvent comprises tetrahydrofuran. In some embodiments, the solvent comprises 1,3-dioxolane. In some embodiments, the solvent comprises ethylene carbonate. In some embodiments, the solvent comprises ethylene glycol dimethyl ether and tetrahydrofuran. In some embodiments, the solvent comprises ethylene glycol dimethyl ether and 1,3-dioxolane.

[0093] All of the above solvents contribute to increasing the coulombic efficiency of the battery at 60° C. When the solvent is selected from one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane, the coulombic efficiency of the battery at room temperature and high temperature can be further increased, the cycle performance of the battery at 25° C. and 60° C. can be improved, and the thickness expansion rate of the battery at 25° C. and 60° C. can be reduced, reducing the amount of gas generation and significantly improving the performance and safety of the battery.

[0094] In this specification, the thickness swelling rate is mainly used to characterize the storage performance of a battery, which can reflect the gas generation amount and stability of the battery, and can be tested by any known method.

[0095] In some embodiments, the polymer comprises one or more of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, perfluoropolyether, poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, optionally comprising one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

[0096] In some embodiments, the polymer comprises polyethylene oxide. In some embodiments, the polymer comprises polyethylene glycol. In some embodiments, the polymer comprises polyvinylpyrrolidone. In some embodiments, the polymer comprises polymethyl methacrylate. In some embodiments, the polymer comprises polyvinylidene fluoride. In some embodiments, the polymer comprises poly(vinylidene fluoride-co-hexafluoropropylene) copolymer. In some embodiments, the polymer comprises perfluoropolyether. In some embodiments, the polymer comprises perfluoropolyether and polyethylene oxide. In some embodiments, the polymer comprises polyethylene glycol and polyethylene oxide.

[0097] All of the above polymers contribute to improving the coulombic efficiency of the battery at 25° C. and 60° C., and the cycle performance of the battery at 60° C. When the polymer is selected from one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, the thickness expansion rate of the battery at 25° C. can be further reduced, the amount of gas generation can be reduced, and the safety of the battery can be significantly improved.

[0098] In some embodiments, the electrolyte salt comprises one or more of sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide; the solvent comprises one or more of ethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane; and the polymer comprises one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

[0099] In some embodiments, the electrolyte salt includes sodium trifluoromethanesulfonate, the solvent includes ethylene glycol dimethyl ether, and the polymer includes polyethylene oxide. In some embodiments, the electrolyte salt includes sodium bis(fluorosulfonyl)imide, the solvent includes ethylene glycol dimethyl ether, and the polymer includes polyethylene oxide. In some embodiments, the electrolyte salt includes sodium bis(fluorosulfonyl)imide, the solvent includes tetrahydrofuran, and the polymer includes polyethylene oxide. In some embodiments, the electrolyte salt includes sodium bis(fluorosulfonyl)imide, the solvent includes ethylene glycol dimethyl ether, and the polymer includes polyethylene glycol. In some embodiments, the electrolyte salt includes sodium bis(fluorosulfonyl)imide, the solvent includes ethylene glycol dimethyl ether, and the polymer includes perfluoropolyether. In some embodiments, the electrolyte salt includes sodium bis(fluorosulfonyl)imide, the solvent includes ethylene glycol dimethyl ether, and the polymer includes poly(vinylidene fluoride-co-hexafluoropropylene) copolymer. In some embodiments, the electrolyte salt comprises sodium bis(fluorosulfonyl)imide, the solvent comprises ethylene glycol dimethyl ether, and the polymer comprises perfluoropolyether and polyethylene oxide.

[0100] The gel electrolyte composition can provide both electrical performance and safety for the battery.

[0101] [Positive electrode] The positive electrode plate includes a positive electrode current collector and a positive electrode active material layer formed on at least a portion of the surface of the positive electrode current collector, the positive electrode active material layer including a positive electrode active material, and the positive electrode active material can include at least one of a layered transition metal oxide, a polyanion-type compound, and a Prussian blue compound.

[0102] The transition metal in the layered transition metal oxide may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. Optionally, the layered transition metal oxide may be, for example, Na x MO2, where M is one or more of Ti, V, Mn, Co, Ni, Fe, Cr, and Cu; <x≦1である。

[0103] Polyanionic compounds include metal ions, transition metal ions, and tetrahedral (YO4) n- The compound may have an anionic unit, wherein the metal ion is optionally one of sodium ion, lithium ion, potassium ion, and zinc ion, the transition metal is optionally at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce, Y is optionally at least one of P, S, and Si, and n is (YO4) n- represents the valence state of

[0104] The Prussian blue compound may be a compound having a sodium ion, a transition metal ion, and a cyanide ion (CN-). The transition metal may be at least one of Mn, Fe, Ni, Co, Cr, Cu, Ti, Zn, V, Zr, and Ce. The Prussian blue compound may be, for example, Na a Me b Me' c (CN)6, where Me and Me' are each independently at least one of Ni, Cu, Fe, Mn, Co, and Zn; <a≦2、0<b<1、0<c<1である。

[0105] In some embodiments, the positive electrode plate includes a positive electrode active material, the positive electrode active material including at least one of a layered transition metal oxide, a polyanionic compound, and a Prussian blue compound, and the positive electrode active material includes NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2, Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 )O2, Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 O2, Na4Fe3(PO4)2P2O7, NaFePO4, Na3V2(PO4)3, Na 1.9 CoFe(CN)6, Na2NiFe(CN)6, NaMnFe(CN)6.

[0106] Any of the above positive electrode active materials can provide the battery with excellent electrical performance.

[0107] In some embodiments, the positive electrode active material has a coating layer on its surface, the coating layer including one or more of a carbon material, ZrO, TiO, polyaniline, polypyrrole, poly(3,4-ethylenedioxythiophene), aluminum oxide, zinc oxide, titanium oxide, zirconium oxide, magnesium oxide, silicon oxide, lanthanum oxide, sodium fluoride, lithium fluoride, and aluminum fluoride, and the carbon material includes one or more of amorphous carbon, graphite, and graphene.

[0108] As used herein, the term "amorphous carbon" refers to a carbon material that has a very low degree of graphitization or crystallization and approximates an amorphous state, and does not have a specific shape or periodic structure. Examples of amorphous carbon include, but are not limited to, carbon black, charcoal, or coke.

[0109] As used herein, the term "graphite" refers to an allotrope of carbon and includes natural graphite and artificial graphite.

[0110] As used herein, the term "graphene" refers to sp 2 It refers to a carbon material in which carbon atoms connected by hybridization are densely stacked in a single layer, two-dimensional honeycomb lattice structure. By way of example, graphene includes, but is not limited to, single-layer graphene and multi-layer graphene.

[0111] As used herein, the term "single-layer graphene" refers to a single-layer sheet structure in which carbon atoms are densely and periodically arranged in a hexagonal honeycomb structure. For example, the thickness of single-layer graphene is only 0.3 nm to 0.4 nm.

[0112] In this specification, the term "multilayer graphene" refers to a graphene produced by stacking 2 to 10 single-layer graphene layers, the total thickness of which is less than 100 nm.

[0113] The coating layer on the surface of the positive electrode active material increases the coulombic efficiency of the battery at room temperature and high temperatures, improves the cycle performance of the battery at 25°C, and reduces the thickness expansion rate of the battery at 25°C and 60°C, further contributing to reducing the amount of gas generation, thereby significantly improving the performance and safety of the battery.

[0114] The positive electrode active material layer may further include a conductive agent to improve the conductive performance of the positive electrode, which may be one or more of Super P, acetylene black, carbon black, ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers.

[0115] The positive electrode active material layer may further include a binder to firmly bond the positive electrode active material and optional conductive agent to the positive electrode current collector, and the binder may optionally be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyethylene alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene-butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0116] The positive electrode current collector may be a conductive carbon sheet, metal foil, carbon-coated metal foil, porous metal plate, or composite current collector. The conductive carbon material of the conductive carbon sheet may be one or more of Super P, carbon black, Ketjen black, carbon dots, carbon nanotubes, graphite, graphene, and carbon nanofibers. The metal material of the metal foil, carbon-coated metal foil, and porous metal plate may each independently be at least one selected from copper, aluminum, nickel, and stainless steel. The composite current collector may be a composite current collector formed by combining a metal foil with a polymer-based film.

[0117] In some embodiments, a positive electrode plate can be manufactured by the following method. The components for manufacturing the positive electrode plate described above, such as the positive electrode active material, conductive agent, binder, and any other optional components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry. The positive electrode slurry is applied to a positive electrode current collector, and after processes such as baking and cold pressing, a positive electrode plate can be obtained.

[0118] [Negative electrode] The negative electrode plate may include only a negative electrode current collector without including a negative electrode active material.

[0119] In some embodiments, the negative electrode current collector may be a metal foil or a composite current collector. For example, the metal foil may be an aluminum foil or a copper foil. The composite current collector may include a polymeric base layer and a metal layer formed on at least one surface of the polymeric substrate. The composite current collector may be formed by forming a metal material (such as copper, copper alloy, nickel, nickel alloy, titanium, titanium alloy, silver, or silver alloy) on a polymeric substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0120] [Separator] In some embodiments, the secondary battery further includes a separator. In the present application, the type of separator is not particularly limited, and any separator with a known porous structure having good chemical stability and mechanical stability can be selected.

[0121] In some embodiments, the separator may be made of at least one of polyethylene, polypropylene, polyvinylidene fluoride, aramid fiber, polyethylene terephthalate, polytetrafluoroethylene, polyacrylonitrile, polyimide, polyamide, polyester, and natural fiber. The separator may be a single-layer film or a multi-layer composite film, and is not particularly limited. When the separator is a multi-layer composite film, the materials of the layers may be the same or different, and are not particularly limited.

[0122] In some embodiments, the positive and negative electrode plates and separators can be manufactured into an electrode assembly by a winding or lamination process.

[0123] In some embodiments, the secondary battery may include an exterior body that can be used to package the electrode assembly and the electrolyte.

[0124] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, or a steel case. The exterior of the secondary battery may be a soft pack, such as a bag-type soft pack. The soft pack may be made of plastic, such as polypropylene, polybutylene terephthalate, or polybutylene succinate.

[0125] [Secondary battery] The secondary battery includes a positive electrode plate and, in some embodiments, a gel electrolyte composition.

[0126] In the present application, the shape of the secondary battery is not particularly limited, and may be cylindrical, rectangular, or any other shape. For example, Fig. 2 shows a secondary battery 5 having a rectangular structure as an example.

[0127] In some embodiments, the secondary battery further comprises a negative electrode plate and a separator.

[0128] In some embodiments, the secondary battery includes at least one of a lithium battery and a sodium battery.

[0129] In some embodiments, the secondary battery includes at least one of a potassium battery, a magnesium battery, and a zinc battery.

[0130] In some embodiments, the secondary battery is a negative electrode-free sodium battery.

[0131] Anode-free sodium batteries do not contain anode active materials, but only anode current collectors. During initial charging, sodium ions gain electrons on the cathode side and deposit as metallic sodium on the surface of the current collector, forming a sodium metal phase. During discharge, the metallic sodium converts back to sodium ions and returns to the cathode, realizing charge-discharge cycling. Compared with sodium-ion secondary batteries and sodium metal batteries, anode-free sodium batteries are not limited by the anode material, allowing for higher energy density. In anode-free sodium batteries, sodium metal is not available as an anode material to provide sufficient sodium element to the battery. Therefore, applying a gel electrolyte composition to anode-free sodium batteries can more effectively improve the cycle performance and safety performance of secondary batteries at room temperature and high temperature.

[0132] In some embodiments, the CB value of the negative electrode-free sodium battery is 0.1 or less.

[0133] The CB value is the capacity per unit area of ​​the negative electrode plate in a secondary battery divided by the capacity per unit area of ​​the positive electrode plate. Because anode-free batteries do not contain negative electrode active material, the capacity per unit area of ​​the negative electrode plate is small, and the CB value of secondary batteries is 0.1 or less.

[0134] In some embodiments, referring to FIG. 3 , the exterior body may include a case 51 and a cover plate 53. The case 51 may include a bottom plate and a side plate connected to the bottom plate, with the bottom plate and side plate being enclosed to form a storage chamber. The case 51 may have an opening communicating with the storage chamber, and the cover plate 53 may cover the opening to seal the storage chamber. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 by a winding process or a stacking process. The electrode assembly 52 is packaged in the storage chamber. A gel electrolyte composition is infiltrated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the lithium-ion battery 5 may be one or more, and can be selected by those skilled in the art according to specific actual needs.

[0135] [Battery module] In some embodiments, the secondary batteries can be assembled into a battery module, and the number of secondary batteries included in the battery module can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery module.

[0136] Fig. 4 shows an example of a battery module 4. Referring to Fig. 4, in the battery module 4, the plurality of secondary batteries 5 may be arranged in order along the longitudinal direction of the battery module 4. Of course, they may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fastening members.

[0137] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in the accommodating space.

[0138] [Battery pack] In some embodiments, the battery modules can be further assembled into a battery pack, and the number of battery modules included in the battery pack can be one or more, and the specific number can be selected by those skilled in the art according to the application and capacity of the battery pack.

[0139] 5 and 6 show an example of a battery pack 1. Referring to FIGS. 5 and 6, the battery pack 1 may include a battery box and a plurality of battery modules 4 provided in the battery box. The battery box may include an upper box 2 and a lower box 3, and the upper box 2 may cover the lower box 3 to form a sealed space for accommodating the battery modules 4. The plurality of battery modules 4 may be arranged in the battery box in any desired form.

[0140] [Power consumption equipment] In one embodiment of the present application, there is provided a power consuming device including at least one of the secondary battery according to any of the embodiments, the battery module according to any of the embodiments, or the battery pack according to any of the embodiments.

[0141] The power consuming device includes at least one of the secondary battery, battery module, or battery pack provided by the present application. The secondary battery, battery module, or battery pack may be used as a power source for the power consuming device or as an energy storage unit for the power consuming device. The power consuming device may include, but is not limited to, mobile devices (e.g., mobile phones, notebook computers, etc.), electric vehicles (e.g., rechargeable battery electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric cars, ships and satellites, energy storage systems, etc.

[0142] As the power consuming device, a secondary battery, a battery module or a battery pack can be selected according to the needs of the usage.

[0143] 7 shows an example of a power consuming device, such as a secondary battery electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. A battery pack or a battery module can be employed to meet the high power and high energy density requirements of the secondary battery of the power consuming device.

[0144] Other example devices may be mobile phones, tablets, laptops, etc. Such devices typically require light weight and thinness, and can employ secondary batteries as their power source.

[0145] Example Examples of the present application are described below. The examples described below are illustrative and are intended merely to interpret the present application and should not be understood as limiting the present application. If specific techniques or conditions are not specified in the examples, they are performed according to the techniques or conditions described in the literature in the field or according to the product specifications. If the manufacturers of the reagents or equipment used are not specified, they are all conventional products that are commercially available.

[0146] 1. Manufacturing method Example 1 1) Preparation of gel electrolyte composition In a dry argon atmosphere, polyethylene oxide (PEO, weight-average molecular weight 600,000), sodium bis(fluorosulfonyl)imide (NaFSI), and a solvent, ethylene glycol dimethyl ether (DME), were mixed at room temperature in a mass ratio of 1:1:3, and the mixture was stirred uniformly until the NaFSI was completely dissolved, thereby obtaining a gel electrolyte composition.

[0147] 2) Manufacturing of positive electrode plates Na4Fe3(PO4)2P2O7 (NFPP) material, conductive carbon black, and binder polyvinylidene fluoride were mixed with N-methylpyrrolidone (NMP) in a weight ratio of 8:1:1 to obtain a positive electrode slurry. The solid content of the slurry was 73%. The positive electrode slurry was then evenly applied to the surface of the aluminum foil positive electrode current collector, and after baking, cold pressing, and cutting, a positive electrode plate was obtained.

[0148] 3) Manufacturing of negative electrode plates Carbon nanotubes and hydroxymethylcellulose (CMC) were mixed in a mass ratio of 5:2 with deionized water and stirred to form a uniform slurry. The slurry was then applied to a copper foil negative electrode current collector, baked, and cut to obtain a negative electrode plate with a negative electrode-free structure.

[0149] 4) Separator A polypropylene film was used as a separator.

[0150] 5) Manufacturing of all batteries For gel electrolyte compositions and liquid electrolytes with viscosities less than 1000 mPa·s, a positive electrode plate, separator, and current collector were stacked in this order, with the separator positioned between the positive and negative current collectors to act as an insulator, and then wound up to obtain a bare cell. Tabs were welded to the bare cell, and the bare cell was then placed in an aluminum case and baked at 80°C to remove moisture. The electrolyte was then immediately injected and the opening was sealed to obtain an uncharged battery. The uncharged battery was then allowed to stand, hot pressed, cold pressed, chemically formed, shaped, and capacity tested to obtain the anode-free sodium metal battery product of Example 1.

[0151] For gel electrolyte compositions and all-solid-state electrolytes with viscosities greater than 1000 mPa·s, the electrolyte was cast onto both sides of the separator, followed by stacking a positive electrode plate, an electrolyte-coated separator, and an anode plate in that order, with the electrolyte-coated separator positioned between the positive and negative electrode pieces to act as an insulator, and then wound up to obtain a bare cell. Tabs were welded to the bare cell, which was then packaged in an aluminum case and baked at 80°C to remove moisture, resulting in an uncharged battery. The uncharged battery was then allowed to stand, hot pressed, cold pressed, formed, shaped, and capacity tested to obtain the anode-free sodium battery product of Example 1.

[0152] 6) Button battery manufacturing In the case of gel electrolyte compositions and liquid electrolytes with viscosities less than 1000 mPa·s, the negative electrode current collector, separator, and sodium sheet were stacked in this order, with the separator positioned between the negative electrode current collector and the sodium sheet to act as an insulator. The electrolyte was then injected and the battery was assembled into a button cell.

[0153] In the case of gel electrolyte compositions with viscosities greater than 1000 mPa·s and all-solid-state electrolytes, a negative electrode current collector, a separator coated by casting on both sides of the electrolyte, and a sodium sheet were stacked in this order, with the separator and electrolyte positioned between the negative electrode current collector and the sodium sheet to act as an insulator, and the opening was then sealed to assemble into a button battery.

[0154] Examples 2 to 4 The batteries of Examples 2 to 4 were manufactured using a method similar to that of Example 1, but the mass contents of the sodium salt, polymer, and solvent were adjusted.

[0155] Example 5 The battery of Example 5 was manufactured in a manner similar to that of Example 1, but the manufacturing method of the gel electrolyte composition was adjusted, and the specific manufacturing method was as follows.

[0156] In a dry argon atmosphere, polyethylene oxide (PEO, weight-average molecular weight 600,000), sodium bis(fluorosulfonyl)imide (NaFSI), and a solvent, ethylene glycol dimethyl ether (DME), were mixed at 60°C in a mass ratio of 1:6:3, and the mixture was stirred uniformly to completely dissolve the NaFSI. The mixture was then cooled to room temperature to obtain a supersaturated gel electrolyte composition.

[0157] Examples 6 to 9 The batteries of Examples 6 to 9 were manufactured using a method similar to that of Example 5, but with the mass contents of sodium salt, polymer and solvent adjusted.

[0158] Examples 10 to 14 The batteries of Examples 10 to 14 were manufactured using a method similar to that of Example 1, but the type of sodium salt was adjusted.

[0159] Examples 15 to 17 The batteries of Examples 15 to 17 were manufactured using a method similar to that of Example 1, but the type of solvent was adjusted.

[0160] Examples 18 to 22 The batteries of Examples 18 to 22 were produced using a method similar to that of Example 1, but the type of polymer was adjusted.

[0161] Example 23 The battery of Example 23 was manufactured in a manner similar to that of Example 1, but the manufacturing method of the gel electrolyte composition was adjusted, and the specific manufacturing method was as follows.

[0162] In a dry argon atmosphere, polyethylene oxide (PEO, weight-average molecular weight 600,000), polyethylene glycol (PEG, weight-average molecular weight 10,000), sodium bis(fluorosulfonyl)imide (NaFSI), and a solvent, ethylene glycol dimethyl ether (DME), were mixed in a mass ratio of 1:1:2:6, and the mixture was stirred uniformly to completely dissolve the NaFSI, thereby obtaining a gel electrolyte composition.

[0163] Examples 24 to 26 The batteries of Examples 24 to 26 were manufactured using a method similar to that of Example 5, but the type and mass content of sodium salt were adjusted.

[0164] Examples 27-28 The batteries of Examples 27 and 28 were manufactured using a method similar to that of Example 5, but the type and mass content of the polymer were adjusted.

[0165] Examples 29-30 The batteries of Examples 29 and 30 were manufactured using a method similar to that of Example 5, but the type of positive electrode active material was adjusted.

[0166] Examples 31-32 The batteries of Examples 31 and 32 were manufactured using a method similar to that of Example 1, but the type of positive electrode active material was adjusted.

[0167] Comparative Example 1 The battery of Comparative Example 1 was manufactured in a similar manner to that of Example 1, except that no polymer was added and a liquid electrolyte was prepared. The specific parameters are as shown in Table 1.

[0168] Comparative Example 2 The battery of Comparative Example 2 was manufactured using a method similar to that of Comparative Example 1, but the type of solvent was adjusted. The specific parameters are as shown in Table 1.

[0169] Comparative Example 3 The battery of Comparative Example 3 was manufactured using a method similar to that of Comparative Example 1, but the type of sodium salt was adjusted. The specific parameters are as shown in Table 1.

[0170] Comparative Examples 4-5 The batteries of Comparative Examples 4 and 5 were manufactured using a method similar to that of Comparative Example 1, but the mass content of sodium salt was adjusted.

[0171] Comparative Example 6 The battery of Comparative Example 6 was manufactured in a similar manner to that of Example 1, except that the gel electrolyte composition was baked to completely remove the solvent to prepare an all-solid electrolyte composition, and the specific parameters were as shown in Table 1.

[0172] Comparative Example 7 The battery of Comparative Example 7 was manufactured in a similar manner to that of Example 6, except that the mass content of sodium salt was adjusted. The specific parameters are as shown in Table 1.

[0173] 2. Performance test 1. Performance test of gel electrolyte composition 1) Viscosity test at different temperatures The prepared gel electrolyte composition was allowed to stand for 10 minutes, and the viscosity value measured using a Dveslvtjo rotational viscometer (BROOKFIELD) was recorded as the viscosity. The test conditions were 25°C, 40°C, 60°C, or 80°C, and a rotation speed of 12 rpm. A 64 rotor was used to measure viscosities of 2000 mPa·s or more, and a 62 rotor was used to measure viscosities of less than 2000 mPa·s. Three parallel measurements were taken, and the average value was calculated.

[0174] 2) Free solvent content test The infrared spectrum of the gel electrolyte composition was measured using a Nicolet iS5 Fourier transform infrared spectrophotometer. After normalization of the spectrogram, the intensity of the solvent characteristic peak was recorded as I1. The solvent of the gel electrolyte composition was used as a reference sample, and its infrared spectrum was measured. After normalization of the spectrogram, the intensity of the corresponding solvent characteristic peak was recorded as I2. I1 / I2 is the ratio of the amount of free solvent to the amount of solvent in the gel electrolyte composition. The characteristic peak of the solvent was selected depending on the type of solvent. For ether solvents, the characteristic peak of CO is between 800 and 900 cm. -1 In the case of ester solvents, the characteristic peak of C=O is located between 850 and 950 cm -1 Between 1700 and 1800 cm -1 When comparing the peak intensities, the peaks are located between 850 and 950 cm. -1 The peak between these two peaks was used as a reference for comparison.

[0175] 3) Testing the median particle size of electrolyte salts precipitated and crystallized from supersaturated gel electrolyte compositions Testing was performed using centrifugal sedimentation and a laser particle size analyzer. The samples were first centrifuged, sedimented, and filtered to obtain the precipitated and crystallized electrolyte salt. Then, 0.1g to 0.13g of the precipitated and crystallized electrolyte salt sample to be tested was weighed into a 50mL beaker, 5g of acetone was added, and a 2.5mm stir bar was inserted and sealed in plastic wrap. The samples were sonicated for 5 minutes, then transferred to a magnetic stirrer and stirred at 500 rpm for at least 20 minutes. Two samples were extracted from each lot and tested. Testing was performed using a Mastersizer 2000E laser particle size analyzer from Malvern Instruments, UK.

[0176] 2. Battery performance test 1) Ionic conductivity test at different temperatures The ionic conductivity of gel electrolyte compositions and all-solid-state electrolytes with viscosities greater than 1000 mPa·s was measured using the following procedure: A 1470 multi-channel electrochemical workstation from Solartron (UK) was used to measure the ohmic resistance of button-type batteries (the positive and negative electrodes were platinum or titanium sheets with the same area). The test temperatures were 25°C, 40°C, 60°C, or 80°C, the frequency range was 1 Hz to 1 MHz, and the perturbation signal was 5 mV. The ionic conductivity was calculated as follows: (electrolyte thickness + separator thickness) / (electrolyte area × electrolyte ohmic resistance). The test procedures for the comparative example and other examples were as described above.

[0177] The ionic conductivity of gel electrolyte compositions and liquid electrolytes with viscosities less than 1000 mPa·s was measured using a Solartron 1470 multichannel electrochemical workstation (UK) to measure the ohmic resistance of button-type batteries (positive and negative electrodes were platinum or titanium sheets of equal area). The separators used were at least three layers, the test temperatures were 25°C, 40°C, 60°C, or 80°C, the frequency range was 1Hz to 1MHz, and the perturbation signal was 5mV. The ionic conductivity was calculated as follows: total thickness of the multilayer separator / (area of ​​electrolyte × ohmic resistance of electrolyte).

[0178] 2) Coulombic efficiency test at different temperatures The Coulombic efficiency test is performed as follows: For all batteries fabricated at 25°C, 40°C, 60°C, or 80°C, the Coulombic efficiency of one cycle is calculated as follows: discharge capacity (Cd1) / charge capacity (Cc1) × 100%, where one cycle is the number of repeated charge-discharge cycles, n being the number of cycles until the capacity retention rate reaches 80%. The average value of the Coulombic efficiencies from the second to nth cycles during the cycle process is calculated as the Coulombic efficiency of the entire battery, and this Coulombic efficiency characterizes the stability of battery performance during the cycle process. The test process for the comparative example and other examples is as described above.

[0179] 3) Testing the number of cycles required to reach 80% capacity retention at room temperature and high temperature The test procedure for cycle capacity retention at room temperature / high temperature was as follows: At 25°C / 60°C and atmospheric pressure (0.1 MPa), the fabricated batteries were charged at a constant current of 1 C until the voltage reached 4 V (layered oxide cathode) or 3.7 V (sodium iron pyrophosphate cathode). They were then charged at a constant voltage of 4 / 3.7 V until the current reached 0.01 C, and subsequently discharged at a constant current of 1 C until the voltage reached 3.0 V. This constituted one charge / discharge cycle. The capacity of the initial discharge was defined as 100%, and the charge / discharge cycle was repeated. When the discharge capacity decreased to 80%, the test was stopped and the number of cycles was recorded. The number of cycles required to reach 80% capacity retention was used as an index for evaluating the cycle performance of the entire battery. The test procedures for the comparative example and other examples were as described above.

[0180] 4) Storage performance at room temperature / high temperature After leaving the fabricated whole battery at 25°C / 60°C for 30 minutes, it was charged to 4V at a constant current of 0.1C, then charged to 0.01C at a constant voltage of 4V, left to stand for 5 minutes, and the thickness of the whole battery was measured. After storing at 25°C / 60°C for 60 days, the thickness of the whole battery was measured and the thickness expansion rate of the battery was calculated using the formula: Thickness expansion rate of whole battery = [(thickness after storage - thickness before storage) / thickness before storage] x 100%. The test process for the comparative example and other examples is as described above.

[0181] 3. Analysis of the test results of each example and comparative example Batteries of each example and comparative example were manufactured by the above method, and performance parameters were measured. The results are shown in Tables 1, 2 and 3 below.

[0182] [Table 1-1] [Table 1-2] [Table 1-3] [Table 1-4] [Table 1-5]

Table 1-6

Table 1-7

[0183]

Table 2-1

Table 2-2

Table 2-3

[0184]

Table 3-1

Table 3-2

[0185] As can be seen from the above results, the gel electrolyte compositions of Examples 1 to 32 had a viscosity at 25°C of 500 mPa·s to 100,000 mPa·s, the sodium salt in the gel electrolyte composition was selected from sodium chloride, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethanesulfonyl)imide, the solvent in the gel electrolyte composition was selected from ethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, or ethylene carbonate, and the polymer in the gel electrolyte composition was selected from one or two of polyethylene oxide, poly(vinylidene fluoride-co-hexafluoropropylene), polyethylene glycol, polyvinylpyrrolidone, and perfluoropolyether. As can be seen from a comparison of Examples 1 to 4, 10 to 23, and 31 to 32 with Comparative Examples 1 to 3, and Examples 5 to 9 and 24 to 30 with Comparative Examples 4 and 5, the gel electrolyte composition has a more suitable viscosity range than the liquid electrolyte, and contributes to increasing the coulombic efficiency of the battery at 60° C. As can be seen from a comparison of Examples 1 to 32 with Comparative Examples 6 and 7, the gel electrolyte composition has a more suitable viscosity range than the all-solid electrolyte, and contributes to increasing the ionic conductivity at 25° C., 40° C., 60° C., and 80° C.

[0186] As can be seen from a comparison between Examples 1 to 32 and Comparative Examples 6 and 7, the amount of free solvent material in the gel electrolyte composition is 0 to 70% based on the total amount of solvent material. Compared with all-solid electrolytes, the gel electrolyte composition has an appropriate range of free solvent mass content, which contributes to the free movement of ions and increases its ionic conductivity at 25°C, 40°C, 60°C, and 80°C.

[0187] As can be seen from a comparison of Examples 1 to 4 with Comparative Examples 1 to 3, and Examples 5 to 9 with Comparative Examples 4 and 5, by controlling the mass content of the sodium salt to 5% to 70% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the coulombic efficiency of the battery at 25°C, 40°C, and 60°C compared to a liquid electrolyte, thereby widening the temperature range of use of the battery. As can be seen from a comparison of Examples 1 to 9 with Comparative Examples 6 and 7, by controlling the mass content of the sodium salt to 5% to 70% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the ionic conductivity at 25°C, 40°C, 60°C, and 80°C compared to an all-solid electrolyte, and can increase the number of cycles until the capacity retention rate of the battery at 25°C reaches 80%, thereby improving battery performance.

[0188] As can be seen from a comparison between Examples 1 to 4 and Comparative Examples 1 to 3, and between Examples 5 to 9 and Comparative Examples 4 and 5, by controlling the mass content of the solvent to be 20% to 75% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the coulombic efficiency of the battery at 25°C, 40°C, and 60°C compared to a liquid electrolyte, thereby widening the temperature range in which the battery can be used. As can be seen from a comparison between Examples 1 to 9 and Comparative Examples 6 and 7, by controlling the mass content of the solvent to be 20% to 75% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the ionic conductivity compared to an all-solid electrolyte, and increase the number of cycles until the capacity retention rate of the battery at 25°C reaches 80%, thereby improving battery performance.

[0189] As can be seen from a comparison between Examples 1 to 4 and Comparative Examples 1 to 3, and between Examples 5 to 9 and Comparative Examples 4 and 5, by controlling the polymer mass content to 2% to 20% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the coulombic efficiency of the battery at 25°C, 40°C, and 60°C compared to a liquid electrolyte, thereby widening the temperature range of use of the battery. As can be seen from a comparison between Examples 1 to 9 and Comparative Examples 6 and 7, by controlling the polymer mass content to 2% to 20% based on the total mass of the gel electrolyte composition, the gel electrolyte composition can effectively increase the ionic conductivity compared to an all-solid electrolyte, and increase the number of cycles until the capacity retention rate of the battery at 25°C reaches 80%, thereby improving battery performance.

[0190] Examples 5 to 9 and 24 to 30 are supersaturated gel electrolyte compositions, which have a viscosity at 25°C of 3000 mPa·s to 100,000 mPa·s, optionally 3000 mPa·s to 11,000 mPa·s, and a viscosity at 60°C of 500 mPa·s to 5,000 mPa·s, optionally 500 mPa·s to 3,000 mPa·s. The sodium salt in the supersaturated gel electrolyte composition is selected from sodium chloride, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, and sodium bis(fluorosulfonyl)imide. The solvent in the supersaturated gel electrolyte composition is selected from ethylene glycol dimethyl ether and ethylene carbonate. The polymer in the supersaturated gel electrolyte composition is selected from one or two of polyethylene oxide, polyethylene glycol, and polyvinylpyrrolidone. As can be seen from a comparison of Examples 5 to 9 and 24 to 30 with Comparative Examples 4 and 5, a supersaturated gel electrolyte composition having an appropriate viscosity range contributes to increasing the coulombic efficiency of a battery at 60°C compared to a liquid electrolyte. As can be seen from a comparison of Examples 5 to 9 and 24 to 30 with Comparative Examples 6 and 7, a supersaturated gel electrolyte composition having an appropriate viscosity range contributes to increasing the ionic conductivity at 25°C, 40°C, 60°C, and 80°C compared to an all-solid electrolyte.

[0191] As can be seen from a comparison of Examples 5 to 9 with Examples 1 to 4, Example 24 with Example 10, Example 25 with Example 12, Example 26 to Example 13, Example 27 to Example 20, Example 28 to Example 21, Example 29 to Example 31, and Example 30 to Example 32, compared with other gel electrolyte compositions, the supersaturated gel electrolyte composition has a higher concentration of sodium salts, including dissolved sodium salts and precipitated and crystallized sodium salts, which contributes to increasing the coulombic efficiency of the battery at 60°C and 80°C, increasing the number of cycles until the capacity retention rate at 60°C reaches 80%, and reducing the thickness expansion rate of the battery at 60°C, thereby improving the high-temperature performance of the battery.

[0192] As can be seen from a comparison of Examples 5 to 9 with Examples 1 to 4, Example 24 with Example 10, Example 25 with Example 12, Example 26 to Example 13, Example 27 to Example 20, Example 28 to Example 21, Example 29 to Example 31, and Example 30 to Example 32, compared to other gel electrolyte compositions, the median particle size of the sodium salt precipitated and crystallized from the supersaturated gel electrolyte composition is 100 μm or less, which increases the coulombic efficiency of the battery at 60°C and 80°C, increases the number of cycles until the capacity retention rate at 60°C reaches 80%, and contributes to a reduction in the thickness expansion rate of the battery at 60°C, thereby improving the high-temperature performance of the battery. As can be seen from a comparison of Examples 5 to 9 and 24 to 30 with Comparative Examples 4 and 5, controlling the mass content of the sodium salt to 30% to 70%, the mass content of the solvent to 20% to 50%, and the mass content of the polymer to 2% to 20%, based on the total mass of the supersaturated gel electrolyte composition, contributes to increasing the coulombic efficiency of the battery at 60°C, compared to a liquid electrolyte. As can be seen from a comparison of Examples 5 to 9 and 24 to 30 with Comparative Examples 6 to 7, controlling the mass content of the sodium salt to 30% to 70%, the mass content of the solvent to 20% to 50%, and the mass content of the polymer to 5% to 20%, based on the total mass of the supersaturated gel electrolyte composition, contributes to increasing the ionic conductivity of the supersaturated gel electrolyte at 25°C, 40°C, 60°C, and 80°C, compared to an all-solid electrolyte.

[0193] As can be seen from a comparison of Examples 1 to 4, Examples 10 to 14 with Comparative Examples 1 to 3, Examples 5 to 9, Examples 24 to 26, and Comparative Examples 4 to 5, when the sodium salt in the gel electrolyte composition is selected from sodium chloride, sodium tetrafluoroborate, sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethanesulfonyl)imide, the Coulombic efficiency of the battery at 60°C and 80°C is increased, contributing to improved battery performance. As can be seen from Examples 1, 12 to 14, and Examples 10 to 11, compared to when the sodium salt is selected from sodium chloride or sodium tetrafluoroborate, when the sodium salt is selected from sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethanesulfonyl)imide, the Coulombic efficiency of the battery at 60°C is further increased, and the number of cycles until the capacity retention rate of the battery at 25°C and 60°C reaches 80% is increased, significantly improving battery performance.

[0194] As can be seen from comparisons of Examples 1 to 4 and 15 to 17 with Comparative Examples 1 to 3, and Examples 5 to 9 with Comparative Examples 4 and 5, using a solvent in a gel electrolyte composition selected from ethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, or ethylene carbonate contributes to improving the Coulombic efficiency of the battery at 60°C. As can be seen from Examples 1, 15 to 16, and 17, compared to when the solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, or 1,3-dioxolane, the Coulombic efficiency of the battery at 25°C, 40°C, 60°C, and 80°C is further improved, the number of cycles until the capacity retention rate of the battery at 25°C and 60°C reaches 80% is increased, and the thickness expansion rate of the battery at 25°C and 60°C is reduced, thereby significantly improving the performance and safety of the battery.

[0195] As can be seen from comparisons of Examples 1 to 4, 18 to 23 with Comparative Examples 1 to 3, 5 to 9, and 27 to 28 with Comparative Examples 4 to 5, selecting one or two of polyethylene oxide, poly(vinylidene fluoride-co-hexafluoropropylene), polyethylene glycol, polyvinylpyrrolidone, and perfluoropolyether as the polymer in the gel electrolyte composition contributes to increasing the battery's coulombic efficiency at 25°C and 60°C and the number of cycles until the battery's capacity retention rate at 60°C reaches 80%. As can be seen from Examples 1, 18 to 20, 22 to 23, and 21, compared to when the polymer is selected from polyvinylpyrrolidone, selecting one or two of polyethylene oxide, poly(vinylidene fluoride-co-hexafluoropropylene), polyethylene glycol, and perfluoropolyether further reduces the battery's thickness expansion rate at 25°C, significantly improving battery safety.

[0196] As can be seen from a comparison of Examples 1, 12 to 16, 18 to 20, 22 to 23 with Examples 10 to 11, 17, and 21, the sodium salt in the gel electrolyte composition is selected from sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, or sodium bis(trifluoromethanesulfonyl)imide, the solvent is selected from ethylene glycol dimethyl ether, tetrahydrofuran, or 1,3-dioxolane, and the polymer is selected from one or two of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, thereby enabling the battery to achieve both good electrical performance and safety.

[0197] As can be seen from the comparison between Example 1 and Examples 31 and 32, Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 ) Na coated with O2, ZrO2, TiO2 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg1 / 18 Compared with the use of O2 as the positive electrode active material, the use of Na4Fe3(PO4)2P2O7 as the positive electrode active material increases the coulombic efficiency of the battery at 25°C, 40°C, 60°C, and 80°C, increases the number of cycles until the battery's capacity retention rate at 25°C and 60°C reaches 80%, and further contributes to reducing the battery's thickness expansion rate at 25°C, thereby significantly improving battery performance and safety.

[0198] As can be seen from the comparison between Example 30 and Example 29, and Example 32 and Example 31, Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 ) Compared to using O2 as the positive electrode active material, Na coated with ZrO2 and TiO2 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 When O2 is used as the positive electrode active material, it can improve the coulombic efficiency of the battery at 25°C, 40°C, 60°C, and 80°C, increase the number of cycles until the capacity retention rate of the battery at 25°C reaches 80%, and further contribute to reducing the thickness expansion rate of the battery at 25°C and 60°C, thereby significantly improving the performance and safety of the battery.

[0199] As can be seen from the comparison between Examples 29 and 31, and between Examples 30 and 32, compared with the unsaturated gel electrolyte composition, the supersaturated gel electrolyte composition improves the coulombic efficiency of the battery at 25°C, 40°C, 60°C, and 80°C, increases the number of cycles until the capacity retention rate of the battery at 25°C and 60°C reaches 80%, and further contributes to reducing the thickness expansion rate of the battery at 25°C and 60°C, thereby significantly improving the performance and safety of the battery.

[0200] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and all embodiments that have substantially the same configuration as the technical idea and exhibit the same functions and effects within the scope of the technical solution of the present application are encompassed within the technical scope of the present application. Furthermore, various modifications that can be conceived by a person skilled in the art to the embodiments and other forms configured by combining some of the components of the embodiments are also encompassed within the scope of the present application, as long as they do not deviate from the gist of the present application. [Explanation of symbols]

[0201] 1 battery pack 2 Upper Box 3 Lower Box 4 Battery Module 5 Secondary battery 51 cases 52 Electrode assembly 53 Cover plate

Claims

1. A gel electrolyte composition having a viscosity at 25°C of 500 mPa·s to 100,000 mPa·s.

2. The gel electrolyte composition contains a solvent, and based on the total amount of the solvent material, a ratio n of the amount of a free solvent material to the total amount of solvent material in the gel electrolyte composition FS is 0% < n FS 2. The gel electrolyte composition according to claim 1, wherein the content of the polymer in the polymer is less than or equal to 70%.

3. 3. The gel electrolyte composition according to claim 1, wherein the mass content of the solvent is 20% to 75% based on the total mass of the gel electrolyte composition.

4. The gel electrolyte composition according to any one of claims 1 to 3, further comprising an electrolyte salt, and a mass content of the electrolyte salt is 5% to 70% based on the total mass of the gel electrolyte composition.

5. The gel electrolyte composition according to any one of claims 1 to 4, characterized in that the gel electrolyte composition further contains a polymer, and a mass content of the polymer is 2% to 20% based on the total mass of the gel electrolyte composition.

6. The gel electrolyte composition according to any one of claims 1 to 5, wherein the gel electrolyte composition is a supersaturated gel electrolyte composition at 25°C.

7. The gel electrolyte composition according to claim 6, wherein the supersaturated gel electrolyte composition has a viscosity of 3,000 mPa·s to 100,000 mPa·s at 25°C and a viscosity of 500 mPa·s to 5,000 mPa·s at 60°C.

8. The gel electrolyte composition according to claim 6 or 7, wherein the supersaturated gel electrolyte composition has a viscosity of 3000 mPa·s to 11000 mPa·s at 25°C and a viscosity of 500 mPa·s to 3000 mPa·s at 60°C.

9. The gel electrolyte composition according to any one of claims 6 to 8, wherein the supersaturated gel electrolyte composition contains a dissolved electrolyte salt and a precipitated and crystallized electrolyte salt.

10. 10. The gel electrolyte composition according to claim 9, wherein the precipitated and crystallized electrolyte salt has a median particle size of 100 μm or less.

11. 11. The gel electrolyte composition according to claim 6, wherein the mass content of the electrolyte salt is 30% to 70%, the mass content of the solvent is 20% to 60%, and the mass content of the polymer is 2% to 20%, based on the total mass of the supersaturated gel electrolyte composition.

12. 12. The gel electrolyte composition according to claim 4, wherein the electrolyte salt comprises a sodium salt, and the sodium salt comprises one or more of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium yttrium fluoride, sodium hexafluoroarsenate, sodium tetraphenylborate, sodium acetate, sodium trifluoroacetate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethanesulfonyl)imide, and sodium (n-nonafluorobutanesulfonyl)imide, and optionally one or more of sodium hexafluorophosphate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide.

13. 13. The gel electrolyte composition according to claim 2, wherein the solvent comprises one or more of an ether organic solvent, an ester organic solvent, and a sulfur-containing organic solvent, and the solvent comprises one or more of ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, tetrahydrofuran, 1,3-dioxolane, ethylene carbonate, propylene carbonate, butylene carbonate, vinylene carbonate, fluoroethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, dipropyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, γ-butyrolactone, 1,3-propane sultone, methyl propionate, methyl butyrate, ethyl acetate, ethyl propionate, propyl propionate, ethyl butyrate, and dimethyl sulfoxide, and optionally comprises one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane.

14. The gel electrolyte composition according to any one of claims 5 to 13, wherein the polymer comprises one or more of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer, and optionally comprises one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

15. 15. The gel electrolyte composition according to claim 5, wherein the electrolyte salt includes one or more of sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, and sodium bis(trifluoromethanesulfonyl)imide; the solvent includes one or more of ethylene glycol dimethyl ether, tetrahydrofuran, and 1,3-dioxolane; and the polymer includes one or more of polyethylene oxide, polyethylene glycol, perfluoropolyether, and poly(vinylidene fluoride-co-hexafluoropropylene) copolymer.

16. A secondary battery comprising a positive electrode plate and the gel electrolyte composition according to any one of claims 1 to 15.

17. 17. The secondary battery according to claim 16, wherein the secondary battery comprises at least one of a lithium battery and a sodium battery.

18. 18. The secondary battery according to claim 16, wherein the secondary battery is a negative electrode free sodium battery.

19. The positive electrode plate includes a positive electrode active material, and the positive electrode active material includes at least one of a transition metal layered oxide, a polyanion compound, and a Prussian blue compound, and NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O 2 , Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 ) O 2 , Na 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 O 2 , Na 4 Fe 3 (P.O. 4 ) 2 P 2 O 7 , NaFePO 4 , Na 3 V 2 (P.O. 4 ) 3 , Na 1.9 CoFe(CN) 6 , Na 2 NiFe(CN) 6 , NaMnFe(CN) 6 19. The secondary battery according to claim 16, wherein the secondary battery comprises one or more of the following:

20. The positive electrode active material has a coating layer on its surface, and the coating layer comprises a carbon material, ZrO 2 , TiO 2 20. The secondary battery according to any one of claims 16 to 19, characterized in that the carbon material comprises one or more of amorphous carbon, graphite, and graphene, and the carbon material comprises one or more of amorphous carbon, graphite, and graphene.

21. A battery module comprising the secondary battery according to any one of claims 16 to 20.

22. A battery pack comprising the secondary battery according to any one of claims 16 to 20 or the battery module according to claim 21.

23. A power consumption device comprising at least one of the secondary battery according to any one of claims 16 to 20, the battery module according to claim 21, or the battery pack according to claim 22.

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