Solid electrolyte, secondary battery, battery module, battery pack, and power consumption device

Abstract

The present application provides a solid electrolyte, a secondary battery, a battery module, a battery pack, and a power consumption device, in which the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°, which is advantageous for improving the interfacial wettability between the solid electrolyte and the positive electrode plate / negative electrode plate, reducing the interfacial resistance, improving the interfacial dynamics, and improving the low-temperature performance of the battery.

Description

[Technical Field]

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

[0002] Sodium batteries have great potential for large-scale energy storage due to their abundant storage capacity, relatively low cost, and wide operating temperature range.

[0003] Currently, sodium batteries generally use liquid electrolytes. However, the solvent in the liquid electrolyte is prone to side reactions with the metal anode, affecting the battery's storage performance and service life. Furthermore, the dissolution of salts lowers the lowest occupied molecular orbital of the solvent, accelerating the decomposition of the liquid electrolyte and gas precipitation, significantly reducing the battery's safety performance. Solid electrolytes, which do not contain solvents and can avoid reactions with the metal anode, have attracted the attention of researchers. However, solid electrolytes have issues with interfacial kinetics, resulting in a significant increase in interfacial resistance during cycling, reducing battery performance and failing to meet the application 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 its object is to provide a solid electrolyte in which the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°, which is advantageous in improving the interfacial wettability between the solid electrolyte and the positive electrode plate / negative electrode plate, reducing the interfacial resistance, improving the interfacial dynamics, and improving the performance of the battery.

[0005] A first aspect of the present application provides a solid electrolyte for a sodium secondary battery, wherein the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°.

[0006] The contact angle of molten sodium on the surface of the solid electrolyte is ≦82°, indicating that the solid electrolyte and molten sodium in this application have better wettability, which can improve the interfacial dynamics between the solid electrolyte and the positive electrode plate / negative electrode plate, reduce the interfacial resistance of the secondary battery, and improve the cycle stability of the sodium secondary battery at room temperature.

[0007] In any embodiment, the solid electrolyte comprises an inorganic solid electrolyte or a polymer solid electrolyte.

[0008] In any embodiment, the mass content of residual alkali in the inorganic solid electrolyte does not exceed 1000 ppm, and optionally is 500 ppm, based on the total mass of the inorganic solid electrolyte.

[0009] Inorganic solid electrolytes are air-sensitive and readily react with water or carbon dioxide in the air to produce residual alkali. Residual alkali in inorganic solid electrolytes severely affects electron transport between the electrolyte and the electrodes, reducing the kinetics and electrochemical performance of the battery. The mass content of residual alkali in the inorganic solid electrolyte of the present application does not exceed 1000 ppm, which is advantageous for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance, and rate performance, significantly improving interfacial kinetics, and improving battery performance. Based on the total mass of the inorganic solid electrolyte, the residual alkali content of the inorganic solid electrolyte is further controlled to not exceed 500 ppm, which is advantageous for further reducing interfacial resistance and significantly improving interfacial kinetics.

[0010] In any embodiment, the inorganic solid electrolyte is tested using XPS, and the content of the amount of substance of sodium element present in the form of residual alkali does not exceed 10% based on the amount of substances of all elements detected.

[0011] The inorganic solid electrolyte was tested using XPS, and based on the amount of all detected elements, the content of sodium element present in the form of residual alkali was found to be no more than 10%, which is beneficial to reducing the interfacial resistance of the battery, improving the coulombic efficiency, cycle performance and rate performance of the battery, significantly improving the interfacial dynamics and improving the battery performance.

[0012] In any embodiment, the inorganic solid electrolyte comprises one or more of a sulfur-based electrolyte, a sodium fast ion conductor, and an oxide electrolyte.

[0013] In any embodiment, the sulfur-based electrolyte is a glassy Na2S-P2S5, Na 11 Sn2PnX 12 , Na3Pn y Pn' 1-y X z X' 4-z wherein Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn' includes at least one of Si, Sn and Ge, and X' includes at least one of F, Br and Cl, and 0 <y≦1、0<z≦4であり、 The sodium fast ion conductor is Na 3+x M y M' 2-y Si 2-z P z O 12 wherein M and M' each independently comprise at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb; and 0≦x≦1, 0 <y≦2、0≦z<2であり、 The oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β"-Al2O3, the Na-β-Al2O3 including β-Na2O·11Al2O3, and the Na-β"-Al2O3 including β"-Na2O·5Al2O3. Optionally, the oxide electrolyte further includes an inorganic oxide including at least one of Li2O, MgO, TiO2, ZrO2, YO3, MnO2, SiO2, and Fe2O3, and the mass content of the inorganic oxide is 0.5% to 30% based on the total mass of the oxide electrolyte.

[0014] Batteries fabricated with the above inorganic solid electrolytes all have relatively low interfacial resistance, excellent coulombic efficiency, cycle stability and rate performance.

[0015] In any embodiment, the polymer solid electrolyte is tested using XPS, and the content of oxygen element substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds does not exceed 10% based on the amount of all detected element substances.

[0016] Several functional groups, such as oxygen-containing functional groups, exist on the surface of the polymer electrolyte. The hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the oxygen-containing functional groups affect interfacial wettability, increase the inhibition of sodium ion migration and diffusion, and reduce the kinetics and electrochemical performance of the battery. XPS was used to test the polymer solid electrolyte. Based on the amount of all detected elemental substances, the content of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds did not exceed 10%, which can reduce surface free energy and improve interfacial wettability, which is beneficial for reducing the interfacial resistance of the battery and improving the battery's room temperature cycle performance.

[0017] In any embodiment, the polymer solid electrolyte comprises a sodium salt and a polymer, and optionally a plasticizer and / or an inorganic filler.

[0018] Batteries fabricated with polymer solid electrolytes containing sodium salts and polymers have relatively low interfacial resistance and excellent cycle performance. Here, the introduction of plasticizers and / or inorganic fillers is advantageous for increasing the plasticity of the polymer solid electrolyte and improving the mechanical performance of the polymer solid electrolyte.

[0019] In any embodiment, the sodium salts include one or more of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttriate, sodium hexafluoroarsenate, sodium acetate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, sodium (normal-perfluorobutylsulfonyl)imide, and optionally one or more of sodium hexafluorophosphate and sodium bis(fluorosulfonyl)imide.

[0020] The sodium salts mentioned above are all advantageous in reducing the interfacial resistance of the battery, improving the interfacial dynamics of the battery, and enhancing the cycle performance of the battery.

[0021] In any embodiment, the polymer comprises one or more of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

[0022] All of the above polymers can improve the mechanical properties of the polymer solid electrolyte and enhance the processability.

[0023] In any embodiment, the polymer solid electrolyte comprises a salt-in-polymer electrolyte, and the mass content of the sodium salt in the salt-in-polymer electrolyte is greater than 50% and less than 100%, based on the total mass of the salt-in-polymer electrolyte.

[0024] The content of oxygen element materials in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the polymer salt-based electrolyte is lower, which is beneficial for further reducing the interfacial resistance of the battery, improving the coulombic efficiency, room temperature / low temperature cycle performance, and rate performance of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0025] In any embodiment, the polymer solid electrolyte comprises a polymer-in-salt electrolyte, and the mass content of the sodium salt in the polymer-in-salt electrolyte is 5% to 50%, based on the total mass of the polymer-in-salt electrolyte.

[0026] The amount of oxygen elemental substances in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the salt-polymer electrolyte is relatively low, which is beneficial for reducing the interfacial resistance of the battery, improving the coulombic efficiency, normal / low temperature cycle performance, and rate performance of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0027] In any of the embodiments, the solid electrolyte is an electrolyte that has been surface treated, and the surface treatment method includes one or more of a nanosecond laser treatment, a magnetron sputtering bias cleaning treatment, and a plasma cleaning treatment.

[0028] All of the above surface treatment methods can reduce the contact angle of the solid electrolyte, improve the interface resistance of the battery, and enhance the performance of the battery.

[0029] In any of the embodiments, the nanosecond laser treatment atmosphere comprises air, the laser wavelength is 250 nm to 3000 nm, optionally 250 nm to 1200 nm, the average laser power is 5 W to 30 W, optionally 10 W to 30 W, the repetition rate is 5 kHz to 40 kHz, the scanning rate is 20 mm / s to 150 mm / s, and the pulse duration is 10 ns to 100 ns, optionally 50 ns to 100 ns.

[0030] By using a nanosecond laser to treat the surface of the solid electrolyte, the contact angle of molten sodium on the surface of the solid electrolyte is reduced to less than 82°, which is beneficial for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance and rate performance at room temperature, improving the interfacial dynamics of the battery, and improving battery performance.

[0031] In any of the embodiments, the atmosphere of the magnetron sputtering bias cleaning process includes vacuum, argon gas, or oxygen gas, and the pressure of the vacuum atmosphere is 10 -4 The pressure of the argon gas or oxygen gas atmosphere is 0.4 Pa to 0.8 Pa, the bias power is 60 W to 100 W, the bias cleaning time is 5 min to 60 min, and the temperature is 20°C to 150°C.

[0032] The surface of the solid electrolyte is cleaned using bias magnetron sputtering, so that the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°, which is beneficial to reducing the interfacial resistance of the battery, improving the room temperature cycle performance of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0033] In any of the embodiments, the atmosphere of the plasma cleaning treatment includes air, vacuum, argon gas, nitrogen gas, or helium gas, and the pressure of the vacuum atmosphere is 10 -4The pressure of the argon gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the nitrogen gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the helium gas atmosphere is 0.2 Pa to 1 Pa, the cleaning power of the plasma cleaning process is 100 W to 3000 W, and the cleaning frequency is 10 -3 The frequency is from 1000 MHz to 3000 MHz, and the cleaning time is from 0.1 min to 10 min.

[0034] Plasma cleaning is used to treat the surface of the solid electrolyte, reducing the contact angle of molten sodium on the surface of the solid electrolyte to less than 82°, which is beneficial for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance and rate performance at room and low temperatures, improving the interfacial dynamics of the battery, and improving battery performance.

[0035] In any of the embodiments, the solid electrolyte is an oxide electrolyte and the method of surface treatment is nanosecond laser treatment.

[0036] For oxide electrolytes, magnetron sputtering bias cleaning treatment or plasma Compared to cleaning treatment, nanosecond laser treatment is advantageous in that it reduces the interfacial resistance of the battery, increases the coulombic efficiency and cycling performance of the battery, improves the interfacial dynamics of the battery, and enhances the performance of the battery.

[0037] A second aspect of the present application provides a secondary battery, which includes the solid electrolyte of the first aspect.

[0038] In any embodiment, the secondary battery is a sodium metal battery.

[0039] In any embodiment, the secondary battery is a sodium secondary battery without a negative electrode.

[0040] In any embodiment, the secondary battery includes a positive electrode plate, the positive electrode plate including a positive electrode active material, and the positive electrode active material including at least one of a layered oxide, a polyanion-type compound, and a Prussian blue compound.

[0041] In any embodiment, the positive electrode active material is 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 It includes one or more of CoFe(CN)6, Na2NiFe(CN)6, and NaMnFe(CN)6.

[0042] The above positive electrode active materials are advantageous in reducing the interface resistance of the battery, improving the cycle performance of the battery, improving the interface dynamics of the battery, and improving the performance of the battery.

[0043] In any embodiment, the surface of the positive electrode active material has a coating layer, 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.

[0044] A positive electrode active material including a coating layer is advantageous in further improving the coulombic efficiency, cycle performance, and rate performance of the battery.

[0045] In any of the embodiments, the thickness of the coating layer is from 2 nm to 1000 nm, and optionally from 10 nm to 100 nm.

[0046] Controlling the thickness of the coating layer within an appropriate range is advantageous for improving the coulomb efficiency and cycle performance of the battery.

[0047] In any embodiment, the secondary battery includes a negative electrode plate, the negative electrode plate including a negative electrode current collector and an undercoating disposed on at least one surface of the negative electrode current collector, the undercoating including one or more of carbon nanotubes, graphite, graphene, silver composite carbon nanoparticles, and tin composite carbon nanoparticles.

[0048] The undercoating not only has excellent electrical conductivity but also favors uniform deposition of metal ions on the surface of the current collector, improving the coulombic efficiency and cycle performance of the battery.

[0049] In any embodiment, the areal density of the undercoating is 5 g / m 2 ~50g / m 2 is.

[0050] Surface density is 5g / m 2 ~50g / m 2 The undercoating, which is favorable for a uniform distribution of nucleation sites, promotes uniform deposition of metal, and at the same time does not affect the electron transport behavior.

[0051] In any embodiment, the undercoating has a thickness of 2 μm to 100 μm.

[0052] Controlling the thickness of the undercoating between 2 μm and 100 μm is beneficial to the uniform deposition of metal ions by providing sufficient nucleation sites, and can suppress dendrites.

[0053] In any embodiment, the interface resistance of the secondary battery is less than 100 Ω.

[0054] A secondary battery with an interfacial resistance smaller than 100 Ω is advantageous for improving the interfacial dynamics of the solid electrolyte and enhancing the performance of the battery.

[0055] A third aspect of the present application provides a battery module, which includes the secondary battery of the second aspect of the present application.

[0056] A fourth aspect of the present application provides a battery pack, which includes the secondary battery of the second aspect of the present application or the battery module of the third aspect of the present application.

[0057] A fifth aspect of the present application provides a power consumption device, the power consumption device including at least one of the secondary battery of the second aspect of the present application, the battery module of the third aspect of the present application, and the battery pack of the fourth aspect of the present application. [Brief explanation of the drawings]

[0058] [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 shown in FIG. 1 according to the embodiment of the present application. [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 consumption device powered by a secondary battery according to an embodiment of the present application; DETAILED DESCRIPTION OF THE INVENTION

[0059] Hereinafter, with appropriate reference to the drawings, embodiments specifically disclosing the solid electrolyte, secondary battery, battery module, battery pack, and electronic device of the present application will be described in detail. However, unnecessary detailed description may be omitted. For example, detailed description of well-known matters or repeated description of structures that are actually the same may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Note that 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 subject matter described in the claims.

[0060] The "ranges" disclosed in this application are defined in the form of lower and upper limits, and a given range is defined by selecting one lower limit and one upper limit, with the selected lower and upper limits defining the boundaries of the particular range. Such defined ranges may be inclusive or exclusive, and any combination is possible; 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 listed for a particular parameter, it is understood that ranges of 60 to 110 and 80 to 120 are also possible. Furthermore, if 1 and 2 are listed as minimum range values ​​and 3, 4, and 5 are listed as maximum range values, the ranges 1 to 3, 1 to 4, 1 to 5, 2 to 3, 2 to 4, and 2 to 5 are all possible. In this application, unless otherwise specified, a numerical range "a to b" is a shorthand notation for any combination of real numbers a to b, where a and b are both real numbers. For example, the numerical range "0-5" represents a list of all real numbers between "0-5" already listed in this specification, and "0-5" is merely a shorthand representation of combinations of these numbers. Also, expressing a parameter as an integer ≧2 is equivalent to disclosing that this parameter is, for example, the integers 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0061] Unless otherwise stated, all embodiments and optional embodiments in the present application can be combined with each other to form a new technical solution.

[0062] Unless otherwise stated, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0063] Unless otherwise specified, all steps in this application may be performed in order or randomly, and are preferably performed in order. For example, when the method includes steps (a) and (b), it means that the method may include steps (a) and (b) performed in order, or steps (b) and (a) performed in order. For example, when the method mentioned above may further include step (c), it means that step (c) may be added to the method in any order, and 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), etc.

[0064] Unless otherwise specified, the terms "comprise" and "comprises" used in this application may be open ended or closed ended. For example, the terms "comprise" and "comprises" may indicate that other components not listed may be further included or included, or that only the listed components may be included or included.

[0065] Unless otherwise stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, "A or B" is satisfied when A is true (or exists) and B is false (or does not exist), when A is false (or does not exist) but B is true (or exists), or when both A and B are true (or exist).

[0066] Solid electrolytes generally include inorganic solid electrolytes and polymer solid electrolytes. Inorganic solid electrolytes are prone to reacting with water in an air atmosphere to produce residual alkalis such as Na2CO3, NaHCO3, or NaOH, which affect the interfacial dynamics of the solid electrolyte. The surface of polymer solid electrolytes contains several functional groups and dangling bonds, which significantly affect the interfacial dynamics of the solid electrolyte and inhibit the migration and diffusion of metal ions. Therefore, new solid electrolytes are needed to meet the application needs of new-generation electrochemical systems.

[0067] [Solid electrolyte] Based on this, the present application provides a solid electrolyte for a sodium secondary battery, in which the contact angle of molten sodium on the surface of the solid electrolyte is smaller than 82°.

[0068] As used herein, the term "sodium secondary battery" refers to a secondary battery that uses sodium ions as a carrier. The negative electrode active material in a sodium secondary battery may be any material, including, but not limited to, hard carbon, sodium metal, transition metal oxides, transition metal selenides, and alloys. Here, the sodium metal may be sodium metal pre-deposited on the negative electrode plate before packaging the battery, or sodium metal deposited on the negative electrode during the battery cycling process. A secondary battery that does not pre-deposit any negative electrode active material on the negative electrode plate before packaging the battery and achieves reversibility of the chemical reaction by desorption / deposition of sodium ions at the positive and negative electrodes is called a negative electrode-less sodium battery and is also a type of sodium secondary battery.

[0069] As used herein, the term "contact angle" refers to the angle at the three-phase boundary between a solid, a liquid, and a gas, from the solid-liquid interface through the liquid to the gas-liquid interface. The contact angle is an important parameter for measuring the wetting ability of a liquid on a material surface. A smaller contact angle indicates that the liquid easily wets the solid, while a larger contact angle indicates that the liquid does not easily wet the solid and moves easily on the surface.

[0070] In this specification, the contact angle of molten sodium on the surface of a solid electrolyte can be tested by selecting a method known in the art, for example, by dropping molten sodium onto the surface of the solid electrolyte, taking an image of the electrolyte surface with a high-resolution camera (Grasshopper GRAS-50S5M-C) equipped with a Fujinon HF75SA-1 lens, and measuring the contact angle using ImageJ software.

[0071] In the prior art, the solid electrolyte and molten sodium have poor wetting properties, with a contact angle of approximately 90° or less. The present application provides a solid electrolyte in which the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°. The solid electrolyte of the present application has better surface wettability, improves the interfacial dynamics between the solid electrolyte and the positive and negative electrodes, reduces the interfacial resistance of the secondary battery, and improves the cycle stability of the sodium secondary battery at room temperature.

[0072] In some embodiments, the solid electrolyte comprises an inorganic solid electrolyte or a polymer solid electrolyte.

[0073] In some embodiments, the mass content of residual alkali in the inorganic solid electrolyte does not exceed 1000 ppm, optionally 500 ppm, based on the total mass of the inorganic solid electrolyte.

[0074] In some embodiments, the residual alkali content of the inorganic solid electrolyte is optionally 10 ppm, 100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm, 700 ppm, 800 ppm, 900 ppm, or 1000 ppm, based on the total mass of the inorganic solid electrolyte.

[0075] In some embodiments, the residual alkalinity of the inorganic solid electrolyte comprises one or more of NaOH, Na2CO3, and NaHCO3.

[0076] In this specification, the residual alkali content of inorganic solid electrolytes can be determined by a method known in the art. For example, it can be determined by potentiometric titration using chemical reagents, referring to standard GB / T 9725-2007. Specifically, using a Swiss Metrohm 905 Titrando potentiometric titrator, the solid electrolyte is immersed in ethylene glycol dimethyl ether (ethylene glycol dimethyl ether) and the ethylene glycol dimethyl ether solution of the solid electrolyte is titrated with a standard titration solution. The potential or pH value is recorded every time 0.1 ml of the standard titration solution is added. The titration is stopped when the potential or pH value no longer changes significantly. The volume of the added standard titration solution and the measured potential or pH value are recorded, and the titration endpoint is determined by a graphical method or a quadratic micrometer method, and the titration volume of the standard titration solution is determined. The calculated masses of NaHCO3, NaOH, and Na2CO3 are divided by the mass of the solid electrolyte to determine the residual alkali content of the solid electrolyte.

[0077] As can be seen, inorganic solid electrolytes are air-sensitive and easily react with water or carbon dioxide in the air to produce residual alkali. Residual alkali in inorganic solid electrolytes severely affects electron transport between the electrolyte and the electrode, reducing the kinetics and electrochemical performance of the battery. Controlling the mass content of residual alkali in inorganic solid electrolytes to no more than 1000 ppm, based on the total mass of the inorganic solid electrolyte, is beneficial for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance, and rate performance, significantly improving interfacial kinetics, and improving battery performance. Furthermore, controlling the mass content of residual alkali in inorganic solid electrolytes to no more than 500 ppm, based on the total mass of the inorganic solid electrolyte, is beneficial for further reducing interfacial resistance and significantly improving interfacial kinetics.

[0078] In some embodiments, the inorganic solid electrolyte is tested using X-ray photoelectron spectroscopy (XPS), and the content of the amount of sodium element present in the form of residual alkali does not exceed 10% based on the amount of all detected elemental substances.

[0079] In some embodiments, the inorganic solid electrolyte is tested using XPS, and the content of the amount of sodium element present in the form of residual alkali is optionally 0.1%, 1%, 1.5%, 2%, 3%, 4%, 4.5%, 5%, 5.5%, 6%, 7%, 8%, 9%, 9.5%, or 10% based on the amount of all detected elemental substances.

[0080] In some embodiments, the residual alkalinity of the inorganic solid electrolyte comprises one or more of NaOH, Na2CO3, and NaHCO3.

[0081] XPS is a surface analysis technique whose detection depth to the sample surface does not exceed 10 nm, so it can analyze the residual alkali content on the surface of inorganic solid electrolytes.

[0082] In this specification, the content of elemental sodium present in the form of residual alkali in an inorganic solid electrolyte can be tested by selecting a method known in the art. For example, the proportion of elements and components within 10 nm of the inorganic solid electrolyte (oxide & NASICON) surface is tested using a Shimadzu Axis Supra+ photoelectron spectrometer. First, XPS full spectrum analysis is performed to obtain the proportion of elemental sodium, and then spectral analysis is performed to determine the proportion of elemental sodium present in the form of residual alkali in the sodium element. Finally, the proportion of elemental sodium present in the form of residual alkali is multiplied by the content of elemental sodium to obtain the proportion of elemental sodium present in the form of residual alkali to the total amount of elemental sodium detected by XPS.

[0083] The inorganic solid electrolyte was tested using XPS, and based on the amount of all detected elements, the content of sodium element present in the form of residual alkali was found to be no more than 10%, which is beneficial to reducing the interfacial resistance of the battery, improving the coulombic efficiency, cycle performance and rate performance of the battery, significantly improving the interfacial dynamics and improving the battery performance.

[0084] In some embodiments, the inorganic solid electrolyte comprises one or more of a sulfur-based electrolyte, a sodium fast ion conductor, and an oxide electrolyte.

[0085] In some embodiments, the sulfur-based electrolyte is a glassy Na2S-P2S5, Na 11 Sn2PnX 12 , Na3Pn y Pn' 1-y X z X' 4-z wherein Pn includes at least one of P and Sb, X includes at least one of S and Se, Pn' includes at least one of Si, Sn and Ge, and X' includes at least one of F, Br and Cl, and 0 <y≦1、0<z≦4である。

[0086] In some embodiments, y is optionally 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0087] In some embodiments, z is optionally 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.4, 1.5, 1.6, 1.8, 2, 2.2, 2.4, 2.5, 2.6, 2.8, 3, 3.2, 3.4, 3.5, 3.6, 3.8, or 4.

[0088] In some embodiments, the sulfur-based electrolyte is Na 11 Sn2PS 12 , Na 10 SnP2S 12 , Na 10 GeP2S 12 , Na 2.9375 PS 3.9375 Cl 0.0625 Includes:

[0089] Sodium fast ion conductor is Na 3+x M y M' 2-y Si 2-z P z O 12wherein M and M' each independently comprise at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb; and 0≦x≦1, 0 <y≦2、0≦z<2である。

[0090] In some embodiments, x is optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, or 1.

[0091] In some embodiments, y is optionally 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0092] In some embodiments, z is optionally 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, or 1.9.

[0093] In some embodiments, the sodium fast ion conductor solid electrolyte is Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 , Na3Zr 1.75 Mg 0.25 SiPO 12 , Na 3.3 Zr 1.7 La 0.3 SiPO 12 , Na 3.1 Ca 0.05 Zr 1.95 SiPO 12 It includes at least one of the following.

[0094] The oxide electrolyte includes at least one of Na-β-Al2O3 and Na-β"-Al2O3, where Na-β-Al2O3 includes β-Na2O·11Al2O3 and Na-β"-Al2O3 includes β"-Na2O·5Al2O3. Optionally, the oxide electrolyte further includes an inorganic oxide, where the inorganic oxide includes at least one of Li2O, MgO, TiO2, ZrO2, YO3, MnO2, SiO2, and Fe2O3. The mass content of the inorganic oxide is 0.5% to 30% based on the total mass of the oxide electrolyte.

[0095] In some embodiments, the inorganic oxide mass content is optionally 0.5%, 1%, 5%, 7%, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, or 30% based on the total mass of the oxide electrolyte.

[0096] Batteries fabricated with the above inorganic solid electrolytes all have relatively low interfacial resistance, excellent coulombic efficiency, cycle stability and rate performance.

[0097] In some embodiments, the polymer solid electrolyte is examined using XPS, and the content of the amount of oxygen elemental substances present in the form of hydrogen-oxygen bond (OH), carbon-oxygen double bond (C=O), and carbon-oxygen single bond (CO) does not exceed 10% based on the amount of all detected elemental substances.

[0098] As used herein, the carbon-oxygen double bond includes any of the forms of a carbonyl group, an ester group, and the like.

[0099] In some embodiments, the polymer solid electrolyte is examined using XPS, and the content of the amount of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds based on the amount of all detected elemental substances is optionally 0.1%, 1%, 1.5%, 2%, 3%, 4%, 4.5%, 5%, 5.5%, 6%, 7%, 8%, 9%, 9.5%, or 10%.

[0100] In this specification, the content of elemental oxygen in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in a polymer solid electrolyte can be determined by any method known in the art. For example, the proportion of elements and components within a 10 nm thickness of the polymer solid electrolyte surface can be determined using a Shimadzu Axis Supra+ photoelectron spectrometer. First, XPS full spectrum analysis can be performed to obtain the proportion of elemental oxygen, followed by spectral analysis to determine the proportion of elemental oxygen in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds. Finally, the proportion of elemental oxygen in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the total amount of elemental oxygen is multiplied by the total amount of elemental oxygen to obtain the proportion of elemental oxygen in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the total amount of elemental oxygen.

[0101] Several functional groups, such as oxygen-containing functional groups, exist on the surface of the polymer electrolyte. The hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds in the oxygen-containing functional groups affect interfacial wettability, increase the inhibition of sodium ion migration and diffusion, and reduce the kinetics and electrochemical performance of the battery. XPS was used to test the polymer solid electrolyte. Based on the amount of all detected elemental substances, the content of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds did not exceed 10%, which can reduce surface free energy and improve interfacial wettability, which is beneficial for reducing the interfacial resistance of the battery and improving the battery's room temperature cycle performance.

[0102] In some embodiments, the polymeric solid electrolyte comprises a sodium salt and a polymer, and optionally comprises a plasticizer and / or an inorganic filler.

[0103] In some embodiments, the plasticizer comprises one or more of 2-ethylhexyl phthalate (DEHP), diisononyl phthalate (DINP), dibutyl phthalate (DBP), dioctyl sebacate (DOS).

[0104] In some embodiments, the inorganic filler comprises one or more of TiO 2 , SiO 2 , Al 2 O 3 , graphene oxide (GO), sulfur-based electrolytes, sodium fast ion conductors, and oxide electrolytes.

[0105] In some embodiments, the mass content of the plasticizer is 1% to 10% based on the total mass of the polymer solid electrolyte, and optionally 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% based on the total mass of the polymer solid electrolyte.

[0106] In some embodiments, the inorganic filler has a mass content of 1% to 10% based on the total mass of the polymer solid electrolyte, and optionally 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10% based on the total mass of the polymer solid electrolyte.

[0107] In some embodiments, the polymer solid electrolyte comprises a sodium salt and a polymer. In some embodiments, the polymer solid electrolyte comprises a sodium salt, a polymer, and a plasticizer. In some embodiments, the polymer solid electrolyte comprises a sodium salt, a polymer, and an inorganic filler.

[0108] Batteries fabricated with polymer solid electrolytes containing sodium salts and polymers have relatively low interfacial resistance and excellent cycle performance. Here, the introduction of plasticizers and / or inorganic fillers is advantageous for increasing the plasticity of the polymer solid electrolyte and improving the mechanical performance of the polymer solid electrolyte.

[0109] In some embodiments, the sodium salt comprises one or more of sodium chloride (NaCl), sodium bromide (NaBr), sodium nitrate (NaNO), sodium perchlorate (NaClO), sodium hexafluorophosphate (NaPF), sodium tetrafluoroborate (NaBF), sodium tetrafluoroyttrium salt (NaYF), sodium hexafluoroarsenate (NaAsF), sodium acetate (CHCOONa), sodium trifluoroacetate (CFCOONa), sodium tetraphenylborate (NaB(CH)), sodium trifluoromethanesulfonate (NaOTf), sodium bis(fluorosulfonyl)imide (NaFSI), sodium bis(trifluoromethylsulfonyl)imide (NaTFSI), sodium (normal-perfluorobutylsulfonyl)imide (NaFNFSI), optionally comprising one or more of sodium hexafluorophosphate (NaPF), sodium bis(fluorosulfonyl)imide (NaFSI).

[0110] Any of the solid electrolytes containing the above sodium salts has an excellent sodium ion transport rate, which is advantageous in improving the conductivity of the battery.

[0111] In some embodiments, the polymer comprises one or more of polyethylene oxide (PEO), polyethylene glycol (PEG), polyvinylpyrrolidone (PVP), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVDF), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), polyvinyl alcohol (PVA), polyacrylonitrile (PAN), polyvinyl chloride (PVC), polyacrylamide (PMA), polytrimethylene carbonate (PTMC), perfluoropolyether (PFPE).

[0112] In some embodiments, the polymer comprises polyethylene oxide. In some embodiments, the polymer comprises polyvinylidene fluoride. In some embodiments, the polymer comprises polyvinylidene fluoride. In some embodiments, the polymer comprises poly(vinylidene fluoride-co-hexafluoropropylene). In some embodiments, the polymer comprises polyethylene oxide and perfluoropolyether.

[0113] All of the above polymers can improve the mechanical properties of the polymer solid electrolyte and enhance the processability.

[0114] In some embodiments, the polymer solid electrolyte comprises a salt-in-polymer electrolyte, and the mass content of the sodium salt in the salt-in-polymer electrolyte is greater than 50% and less than 100%, based on the total mass of the salt-in-polymer electrolyte.

[0115] In some embodiments, the polymer solid electrolyte comprises a salt-in-polymer electrolyte, and the mass content of the sodium salt in the salt-in-polymer electrolyte is greater than 50% and less than 80%, based on the total mass of the salt-in-polymer electrolyte.

[0116] In some embodiments, the mass content of the sodium salt in the salt-in-polymer electrolyte is optionally 51%, 55%, 60%, 65%, 70%, 75%, based on the total mass of the salt-in-polymer electrolyte.

[0117] The amount of oxygen elemental materials present in the form of OH, C=O and CO on the surface of the polymer salt-based electrolyte is lower, which is beneficial for further reducing the interfacial resistance of the battery, improving the coulombic efficiency, cycle performance and rate performance at room / low temperatures of the battery, improving the interfacial dynamics of the battery and improving the performance of the battery.

[0118] In some embodiments, the polymer solid electrolyte comprises a polymer-in-salt electrolyte, and the mass content of the sodium salt in the polymer-in-salt electrolyte is 5% to 50%, based on the total mass of the polymer-in-salt electrolyte.

[0119] In some embodiments, the mass content of the sodium salt in the polymer-in-salt electrolyte is optionally 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, based on the total mass of the polymer-in-salt electrolyte.

[0120] A low content of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds on the surface of the salt-polymer electrolyte is advantageous for reducing the interfacial resistance of the battery, improving the coulombic efficiency, cycle performance and rate performance at room and low temperatures of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0121] In some embodiments, the solid electrolyte is an electrolyte after being surface treated, and the method of surface treatment includes one or more of a nanosecond laser treatment, a magnetron sputtering bias cleaning treatment, and a plasma cleaning treatment.

[0122] In some embodiments, the method of surface treatment comprises a nanosecond laser treatment, in some embodiments, the method of surface treatment comprises a magnetron sputtering bias cleaning treatment, in some embodiments, the method of surface treatment comprises a plasma cleaning treatment.

[0123] The above-mentioned surface treatment methods can either remove residual alkali on the surface of the inorganic solid electrolyte or selectively remove oxygen-containing groups such as hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds on the surface of the polymer solid electrolyte, which is advantageous in improving the interface wettability, reducing the contact angle of the solid electrolyte, improving the interface resistance of the battery, and improving the battery performance.

[0124] In some embodiments, the nanosecond laser treatment atmosphere comprises air, the laser wavelength is between 250 nm and 3000 nm, optionally between 250 nm and 1200 nm, the average laser power is between 5 W and 30 W, optionally between 10 W and 30 W, the repetition rate is between 5 kHz and 40 kHz, the scanning frequency is between 20 mm / s and 150 mm / s, and the pulse duration is between 10 ns and 100 ns, optionally between 50 ns and 100 ns.

[0125] In some embodiments, the laser wavelength is optionally 266 nm, 355 nm, 532 nm, 633 nm, 785 nm, 1064 nm, 2940 nm, the average laser power is optionally 5 W, 8 W, 10 W, 13 W, 17 W, 10 W, 20 W, 22 W, 25 W, 28 W, or 30 W, and the repetition rate is optionally 5 kHz, 10 kHz, 15 kHz, 20 kHz, 25 kHz. , 30 kHz, 35 kHz or 40 kHz, the scanning frequency is optionally 20 mm / s, 40 mm / s, 50 mm / s, 60 mm / s, 80 mm / s, 100 mm / s, 120 mm / s, 140 mm / s or 150 mm / s, and the pulse duration is optionally 10 ns, 20 ns, 30 ns, 40 ns, 50 ns, 60 ns, 70 ns, 80 ns, 90 ns or 100 ns.

[0126] By using a nanosecond laser to treat the surface of the solid electrolyte, the contact angle of molten sodium on the surface of the solid electrolyte is reduced to less than 82°, which is beneficial for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance and rate performance at room temperature, improving the interfacial dynamics of the battery, and improving battery performance.

[0127] In some embodiments, the atmosphere of the magnetron sputtering bias cleaning process comprises vacuum, argon gas, or oxygen gas, and the pressure of the vacuum atmosphere is 10 -4 The pressure of the argon gas or oxygen gas atmosphere is 0.4 Pa to 0.8 Pa, the bias power is 60 W to 100 W, the bias cleaning time is 5 min to 60 min, and the temperature is 20°C to 150°C.

[0128] In some embodiments, the pressure of the vacuum atmosphere is optionally 10 -4 Pa, 5 × 10 -3 Pa, 10 -3 Pa, 5 × 10 -2 Pa, 10 -2 Pa, 0.1 Pa, 0.2 Pa, 0.5 Pa, 0.8 Pa or 1 Pa, the pressure of the argon gas or oxygen gas atmosphere is selectively 0.4 Pa, 0.45 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, 0.65 Pa, 0.7 Pa, 0.75 Pa or 0.8 Pa, Power is optionally 60W, 65W, 70W, 75W, 80W, 85W, 90W, 95W or 100W, the bias cleaning time is optionally 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, and the temperature is optionally 20°C, 40°C, 50°C, 60°C, 80°C, 100°C, 120°C, 140°C or 150°C.

[0129] The surface of the solid electrolyte is cleaned using bias magnetron sputtering, so that the contact angle of molten sodium on the surface of the solid electrolyte is less than 82°, which is beneficial to reducing the interfacial resistance of the battery, improving the room temperature cycle performance of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0130] In some embodiments, the atmosphere of the plasma cleaning process comprises air, vacuum, argon gas, nitrogen gas, or helium gas, and the pressure of the vacuum atmosphere is 10 -4 The pressure of the argon gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the nitrogen gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the helium gas atmosphere is 0.2 Pa to 1 Pa, the cleaning power of the plasma cleaning process is 100 W to 3000 W, and the cleaning frequency is 10 -3 The frequency is from 1000 MHz to 3000 MHz, and the cleaning time is from 0.1 min to 10 min.

[0131] In some embodiments, the pressure of the vacuum atmosphere is 10 -4 Pa, 5 × 10 -3 Pa, 10 -3 Pa, 5 × 10 -2 Pa, 10 -2 The pressure of the argon gas atmosphere is 0.2 Pa, 0.4 Pa, 0.45 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, 0.65 Pa, 0.7 Pa, 0.75 Pa, 0.8 Pa, 0.9 Pa, or 1 Pa, and the pressure of the nitrogen gas atmosphere is 0.2 Pa, 0.4 Pa, 0.45 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, 0.65 Pa, 0.7 Pa, 0.75 Pa, 0.8 Pa, 0.9 Pa, or 1 Pa. The pressure of the helium gas atmosphere is 0.2 Pa, 0.4 Pa, 0.45 Pa, 0.5 Pa, 0.55 Pa, 0.6 Pa, 0.65 Pa, 0.7 Pa, 0.75 Pa, 0.8 Pa, 0.9 Pa, or 1 Pa; the cleaning power of the plasma cleaning process is selectively 100 W, 500 W, 1000 W, 1300 W, 1500 W, 1700 W, 2000 W, 2200 W, 2500 W, 2800 W, or 3000 W; and the cleaning frequency is selectively 4×10 -2 MHz, 13.56MHz, 2.45×10 3 MHz and the cleaning time is optionally 0.1 min, 0.5 min, 1 min, 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min.

[0132] Plasma cleaning is used to treat the surface of the solid electrolyte, reducing the contact angle of molten sodium on the surface of the solid electrolyte to less than 82°, which is beneficial for reducing the interfacial resistance of the battery, improving the battery's coulombic efficiency, cycle performance and rate performance at room and low temperatures, improving the interfacial dynamics of the battery, and improving battery performance.

[0133] The applicant unexpectedly discovered that although too high a treatment power / time can further reduce the content of surface functional groups and improve the interfacial dynamics performance, it also brings about certain damage to the main body material, which is unfavorable for further improving the cycle performance.

[0134] In some embodiments, the solid electrolyte is an oxide electrolyte and the method of surface treatment is nanosecond laser treatment.

[0135] For oxide electrolytes, magnetron sputtering bias cleaning treatment or plasma Compared to cleaning treatments, nanosecond laser treatments are advantageous in that they reduce the surface free energy of the oxide electrolyte, further reducing the interfacial resistance of the battery, improving the coulombic efficiency and cycling performance of the battery, improving the interfacial dynamics of the battery, and improving the performance of the battery.

[0136] [Positive electrode plate] In some embodiments, 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-type compound, and a Prussian blue compound.

[0137] In some embodiments, 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 at least one of, 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。

[0138] In some embodiments, the polyanionic compound comprises a metal ion, a transition metal ion, and a tetrahedral (YO4) n - It may be a type of compound having 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

[0139] In some embodiments, the Prussian blue-based compound comprises sodium ions, transition metal ions, and cyanide ions (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。

[0140] In some embodiments, the positive electrode active material is 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 It includes one or more of CoFe(CN)6, Na2NiFe(CN)6, and NaMnFe(CN)6.

[0141] The above positive electrode active materials are advantageous in that they widen the electrochemical window of the battery, improve the storage performance of the battery, reduce the gas generation rate of the battery, and improve the safety of the battery.

[0142] In some embodiments, the surface of the positive electrode active material has a coating layer, 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.

[0143] As used herein, the term "amorphous carbon" refers to a carbon material that has a very low degree of graphitization crystallization and is close to an amorphous form, and does not have a specific shape or periodic structure. By way of example, amorphous carbon includes, but is not limited to, carbon black, charcoal, or coke.

[0144] As used herein, the term "graphite" refers to allotropes of carbon, including natural and synthetic graphite.

[0145] As used herein, the term "graphene" refers to sp 2 It refers to a carbon material in which hybridized bonded carbon atoms 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 or multi-layer graphene.

[0146] As used herein, the term "single-layer graphene" refers to a single-layer sheet-like structure in which carbon atoms are tightly 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.

[0147] As used herein, the term "multilayer graphene" refers to a graphene produced by stacking 2 to 10 single-layer graphene layers together to a total thickness of less than 100 nm.

[0148] A positive electrode active material including a coating layer is advantageous in improving the cycle performance and storage performance of a battery.

[0149] In some embodiments, the thickness of the coating layer is between 2 nm and 1000 nm, and optionally between 10 nm and 100 nm.

[0150] In some embodiments, the thickness of the coating layer is optionally 2 nm, 5 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1000 nm.

[0151] Controlling the thickness of the coating layer within an appropriate range is advantageous for improving the cycle stability and electrical performance at high voltage of the battery.

[0152] The positive electrode plate 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.

[0153] The positive electrode plate may further include an adhesive for firmly adhering the positive electrode active material and optional conductive agent to the positive electrode current collector, and the adhesive may be at least one of polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), polyacrylic acid (PAA), polyvinyl alcohol (PVA), ethylene-vinyl acetate copolymer (EVA), styrene butadiene rubber (SBR), carboxymethyl cellulose (CMC), sodium alginate (SA), polymethacrylic acid (PMA), and carboxymethyl chitosan (CMCS).

[0154] The positive electrode plate further includes a positive electrode current collector, which may be a conductive carbon sheet, a metal foil, a carbon-coated metal foil, a porous metal plate, or a 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 materials of the metal foil, the carbon-coated metal foil, and the porous metal plate may each independently be at least one of 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 base film.

[0155] In some embodiments, the positive electrode plate may be manufactured in the following manner: Components for manufacturing the positive electrode plate, such as a positive electrode active material, a conductive agent, an adhesive, and any other components, are dispersed in a solvent (e.g., N-methylpyrrolidone) to form a positive electrode slurry, which is then applied onto a positive electrode current collector, and the positive electrode plate is obtained after processes such as drying and cold pressing.

[0156] [Negative electrode plate] In some embodiments, the negative electrode plate includes a negative electrode current collector and an undercoating disposed on at least one surface of the negative electrode current collector, the undercoating including one or more of carbon nanotubes, graphite, graphene, silver composite carbon nanoparticles, and tin composite carbon nanoparticles.

[0157] The undercoating not only has excellent electrical conductivity but also favors uniform deposition of metal ions on the surface of the current collector, improving the cycle performance and safety of the battery.

[0158] In some embodiments, the negative electrode plate may include only a negative electrode current collector with an undercoating and no negative electrode active material. The negative electrode plate may have a metallic phase pre-deposited on a negative electrode current collector with an undercoating.

[0159] In some embodiments, the negative electrode current collector may employ a metal foil sheet or a composite current collector. For example, aluminum foil or copper foil may be used as the metal foil sheet. The composite current collector may include a polymer base layer and a metal layer formed on at least one surface of the polymer 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 polymer substrate (such as a substrate of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polystyrene (PS), or polyethylene (PE)).

[0160] In some embodiments, the areal density of the undercoating is 5 g / m 2 ~50g / m 2 is.

[0161] In some embodiments, the areal density of the undercoating is optionally 5 g / m 2 , 10g / m 2 , 15g / m 2 , 20g / m 2 , 25g / m 2 , 30g / m 2 , 35g / m 2 , 40g / m 2 , 45g / m 2 or 50g / m 2 be.

[0162] Surface density is 5g / m 2 ~50g / m 2 The undercoating, which is favorable for the uniform distribution of nucleation sites in the anode-less battery, promotes uniform deposition of metal, and at the same time does not affect the electron transport behavior.

[0163] In some embodiments, the undercoating has a thickness of between 2 μm and 100 μm.

[0164] In some embodiments, the thickness of the undercoating is optionally 2 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.

[0165] Controlling the thickness of the undercoating between 2 μm and 100 μm is beneficial to the uniform deposition of metal ions by providing sufficient nucleation sites, and can suppress dendrites.

[0166] [Secondary battery] The secondary battery includes a solid electrolyte in some embodiments.

[0167] In some embodiments, the secondary battery further comprises a positive electrode plate, a negative electrode plate, and a separator.

[0168] In some embodiments, the secondary battery is a sodium metal battery.

[0169] In a sodium metal battery, metallic sodium is pre-deposited on the negative electrode current collector to form a sodium metal phase as the negative electrode active material. During the charge and discharge process, sodium ions gain electrons on the positive electrode side and deposit as metallic sodium on the current collector surface to form a sodium metal phase. The metallic sodium can also be converted back to sodium ions and returned to the positive electrode, realizing cycle charge and discharge. Compared to conventional sodium-ion batteries, sodium metal has a higher capacity, which significantly improves the energy density of sodium metal batteries.

[0170] In some embodiments, the secondary battery is a sodium secondary battery without a negative electrode.

[0171] Anode-less sodium secondary batteries contain only anode current collectors and no anode active material. During initial charging, sodium ions gain electrons at the anode side and deposit on the current collector surface as metallic sodium, forming a sodium metal phase. During discharge, metallic sodium converts back to sodium ions and returns to the cathode, achieving cycle charging and discharging. Compared to other sodium secondary batteries, anode-less sodium secondary batteries are not limited by the anode material, allowing for higher energy density. Furthermore, anode-less sodium secondary batteries maintain high electrochemical performance while significantly reducing the manufacturing process, improving production cycles, and reducing battery costs.

[0172] In some embodiments, the CB value of a sodium battery without a negative electrode is 0.1 or less.

[0173] 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. Since batteries without a negative electrode do not contain negative electrode active material, the capacity per unit area of ​​the negative electrode plate is relatively small, and the CB value of the secondary battery is 0.1 or less.

[0174] In some embodiments, the interfacial resistance of the secondary battery is less than 100 Ω.

[0175] In some embodiments, the interfacial resistance of the secondary battery is optionally 1 Ω, 5 Ω, 10 Ω, 15 Ω, 20 Ω, 25 Ω, 30 Ω, 35 Ω, 40 Ω, 45 Ω, 50 Ω, 55 Ω, 60 Ω, 65 Ω, 70 Ω, 75 Ω, 80 Ω, 85 Ω, 90 Ω, 95 Ω, or 99 Ω.

[0176] In this specification, the interfacial resistance of a secondary battery may be tested by any method known in the art. For example, the AC impedance spectrum of a full battery is measured at 25°C using a 1470 multi-channel electrochemical workstation manufactured by Solartron, UK, with a frequency range of 1 Hz to 1 MHz and a perturbation signal of 5 mV. After the relevant electrochemical impedance spectrum is obtained, it is fitted using Zview software, and a capacitive reactance value of 1×10 is obtained.-7 and 1×10 -5 The diameter obtained after fitting to the arc between is taken as the interface resistance. For the manufacturing method of the full battery, refer to the manufacturing method in the examples of this application.

[0177] A secondary battery with an interfacial resistance smaller than 100 Ω is advantageous for improving the interfacial dynamics of the solid electrolyte and enhancing the performance of the battery.

[0178] In some embodiments, the positive and negative electrodes and the separator can be fabricated into an electrode assembly by a winding or lamination process.

[0179] In some embodiments, the secondary battery may include an exterior body, which may be used to package the electrode assembly and the electrolyte.

[0180] In some embodiments, the exterior of the secondary battery may be a hard case, such as a hard plastic case, an aluminum case, a steel case, etc. The exterior of the secondary battery may be a pouch, such as a bag-shaped pouch. The pouch may be made of plastic, such as polypropylene, polybutylene terephthalate, and polybutylene succinate.

[0181] The present application does not particularly limit the shape of the secondary battery, and it may be cylindrical, rectangular, or any other shape. For example, Fig. 1 shows an example of a rectangular secondary battery 5, and Fig. 2 is an exploded view of the secondary battery 5.

[0182] In some embodiments, referring to FIG. 2 , the exterior body may include a case 51 and a cover plate 53. Here, the case 51 may include a bottom plate and a side plate connected to the bottom plate, where the bottom plate and the side plate together form a surrounding accommodating cavity. The case 51 has an opening communicating with the accommodating cavity, and the cover plate 53 can be installed to cover the opening to seal the accommodating cavity. The positive electrode plate, the negative electrode plate, and the separator may be formed into an electrode assembly 52 through a winding process or a stacking process. The electrode assembly 52 is packaged within the accommodating cavity. A non-Newtonian fluid electrolyte composition is infiltrated into the electrode assembly 52. ​​The number of electrode assemblies 52 included in the secondary battery 5 may be one or more, and those skilled in the art can select the number according to actual needs.

[0183] [Battery module] In some embodiments, the secondary batteries may be assembled into a battery module, and the number of secondary batteries included in the battery module may be one or more, and the specific number may be selected by those skilled in the art according to the application and capacity of the battery module.

[0184] FIG. 3 shows an example of a battery module. 4 3, a plurality of secondary batteries 5 may be arranged in a battery module 4 in order along the longitudinal direction of the battery module 4. Of course, the batteries may be arranged in any other manner. Furthermore, the plurality of secondary batteries 5 may be fixed by fasteners.

[0185] Optionally, the battery module 4 may further include a housing having an accommodating space, and the plurality of secondary batteries 5 are accommodated in this accommodating space.

[0186] [Battery pack] In some embodiments, the battery modules may be assembled into a battery pack, and the battery pack may include one or more battery modules, the specific number of which may be selected by those skilled in the art depending on the application and capacity of the battery pack.

[0187] 4 and 5 show an example of a battery pack 1. Referring to FIGS. 4 and 5, the battery pack 1 may include a battery box and a plurality of battery modules 4 installed in the battery box. The battery box includes an upper housing 2 and a lower housing 3, and the upper housing 2 may be provided with a lid on the lower housing 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 manner.

[0188] [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 of any of the embodiments, the battery module of any of the embodiments, or the battery pack of any of the embodiments.

[0189] The power consuming device includes at least one of a secondary battery, a battery module, or a battery pack according to the present application. The secondary battery, the battery module, or the 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, laptops, etc.), electric vehicles (e.g., pure electric vehicles, hybrid electric vehicles, plug-in hybrid electric vehicles, electric bicycles, electric scooters, electric golf carts, electric trucks, etc.), electric trains, ships, satellites, energy storage systems, etc.

[0190] The power consumption device can be selected from a secondary battery, a battery module, or a battery pack depending on its usage needs.

[0191] 6 shows an example of a power consuming device, such as a pure electric vehicle, a hybrid electric vehicle, or a plug-in hybrid electric vehicle. To meet the demand for high power output and high energy density of the secondary battery of the power consuming device, a battery pack or battery module can be employed.

[0192] Other examples of the device may include a mobile phone, a tablet computer, a laptop computer, etc. These devices are generally required to be thin and lightweight, and may use a secondary battery as a power source.

[0193] Example The following examples of the present application are described. The examples described below are illustrative and are used only to interpret the present application and should not be understood as limitations on the present application. Unless specific techniques or conditions are specified in the examples, they are carried out according to the techniques or conditions described in literature in the field or according to the product instructions. Unless the manufacturer is specified, the reagents or equipment used are all commercially available products.

[0194] 1. Manufacturing method Example 1 1) Treatment of solid electrolytes Surface treatment of solid electrolyte: The electrolyte β-Na2O·11Al2O3 was surface treated using a nanosecond laser. The atmosphere for the nanosecond laser treatment was air, the laser wavelength was 1000 nm, the average laser power was 20 W, the repetition rate was 30 kHz, the scanning frequency was 100 mm / s, and the pulse duration was 50 ns.

[0195] 2) Manufacturing of positive electrode plates First, β-Na2O·11Al2O3 solid electrolyte powder with a particle size of less than 50 μm and carbon-coated sodium iron pyrophosphate (Na4Fe3(PO4)2P2O7 / C) powder were uniformly mixed in a mass ratio of 7:13 to obtain a mixed powder. 2.5 wt.% polyvinylidene fluoride (PVDF) adhesive was thoroughly dissolved in N-methylpyrrolidone (NMP). Next, 2.0 wt.% Super P, 1.0 wt.% carbon nanotubes, and 94.5 wt.% of the mixed powder were added and stirred uniformly to obtain a positive electrode slurry. The slurry was uniformly applied to the surface of aluminum foil current collector and then transferred to a vacuum oven for complete drying. After drying, the electrode plate was roll-pressed and punched to obtain a positive electrode plate.

[0196] 3) Manufacturing of negative electrode plates Negative electrode plate without a negative electrode structure: Carbon nanotubes (CNTs) and carboxymethyl cellulose (CMC) are added to deionized water in a mass ratio of 1:0.4 and stirred to form a uniform slurry. The slurry is then applied to the surface of the negative electrode current collector copper foil, which is then transferred to a vacuum oven and completely dried to obtain an undercoating. The negative electrode plate without a negative electrode structure is then punched out, where the areal density of the undercoating is 10 g / m. 2 where the thickness of the undercoating is 5 μm.

[0197] 4) Battery manufacturing The positive electrode plate, surface-treated solid electrolyte, and negative electrode plate were stacked in this order and then wound to obtain a bare cell. A tab was welded to the bare cell, and the bare cell was placed in an aluminum case and baked at 80°C to remove water. The case was then sealed to obtain an uncharged battery. The uncharged battery was then subjected to further processes such as standing, hot pressing, chemical formation, and capacity testing to obtain the negative-electrode-free sodium metal battery product of Example 1.

[0198] Examples 2 to 27 The batteries of Examples 2 to 27 were manufactured using a method similar to that of Example 1, but the type of solid electrolyte or the surface treatment method was adjusted. Specific parameters are as shown in Tables 1, 2 and 3.

[0199] Here, in Example 8 The polymer solid electrolyte was prepared as follows: sodium bis(fluorosulfonyl)imide (NaFSI) and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were mixed in a ratio of 3:2 in a dry argon gas atmosphere to obtain a NaFSI / PVDF-HFP polymer solid electrolyte.

[0200] Comparative Example 1 The manufacturing method of the battery of Comparative Example 1 was almost the same as that of Example 1, but the solid electrolyte was not subjected to a surface treatment.

[0201] Comparative Examples 2 to 9 The manufacturing method of the batteries in Comparative Examples 2 to 9 was almost the same as that in Comparative Example 1, but the type of solid electrolyte was adjusted.

[0202] 2. Performance test 1, solid electrolyte 1) Acid-alkali titration test for residual alkali in inorganic solid electrolytes This can be determined by potentiometric titration of chemical reagents, for example, with reference to standard GB / T 9725-2007. Specifically, using a Swiss Metrohm 905 Titrando potentiometric titrator, the solid electrolyte is immersed in ethylene glycol dimethyl ether (EGE), and the EGE solution is titrated with the standard titration solution. After each 0.1 ml of standard titration solution is added, the potential or pH is recorded. The titration is stopped when the potential or pH no longer changes significantly. The volume of the added standard titration solution and the measured potential or pH are recorded, and the titration endpoint is determined by a graphical or quadratic micrometer method, and the titration volume of the standard titration solution is determined. The calculated masses of NaHCO3, NaOH, and Na2CO3 are divided by the mass of the solid electrolyte to determine the residual alkalinity of the solid electrolyte.

[0203] 2) The proportion of the amount of sodium element present in the form of residual alkali in inorganic solid electrolytes - X-ray photoelectron spectroscopy (XPS) test The proportions of elements and components within 10 nm of the inorganic solid electrolyte (oxide & NASICON) surface were examined using a Shimadzu Axis Supra+ photoelectron spectrometer. First, an XPS full spectrum analysis was performed to obtain the proportion of elemental sodium. Next, spectral analysis was performed to determine the proportion of elemental sodium present in the forms of Na2CO3, NaOH, and NaHCO3. Finally, the proportion of elemental sodium present in the forms of Na2CO3, NaOH, and NaHCO3 was multiplied by the amount of elemental sodium present to obtain the proportion of elemental sodium present in the forms of Na2CO3, NaOH, and NaHCO3 to the total amount of elemental sodium detected by XPS.

[0204] XPS is a method for evaluating surface characteristics, and therefore the main object of measurement is the amount of residual alkali on the surface.

[0205] 3) Examination of the oxygen element content present as hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds on the surface of polymer solid electrolyte The proportions of elements and components within a 10-nm thickness of the polymer solid electrolyte surface were examined using a Shimadzu Axis Supra+ photoelectron spectrometer. First, an XPS full spectrum analysis was performed to obtain the proportion of oxygen elemental substances. Next, spectral analysis was performed to determine the ratio of the amount of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds to the amount of oxygen elemental substances. Finally, the amount of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds was multiplied by the amount of oxygen elemental substances to obtain the proportion of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds to the amount of all elemental substances detected by XPS.

[0206] 4) Contact angle test After dropping molten sodium onto the surface of the solid electrolyte, the electrolyte surface image was taken with a high-resolution camera (Grasshopper GRAS-50S5M-C) equipped with a Fujinon HF75SA-1 lens, and the contact angle was measured with ImageJ software. The test process for the comparative example and other examples was the same as above.

[0207] 2. Battery performance test 1) Interface resistance test The test process for interface resistance is as follows: An electrochemical AC impedance test was performed on the assembled full battery. The AC impedance spectrum of the full battery was measured at 25°C using a Solartron 1470 multi-channel electrochemical workstation (UK). The frequency range was 1 Hz to 1 MHz, and the perturbation signal was 5 mV. After obtaining the relevant electrochemical impedance spectrum, it was fitted using Zview software, and the capacitive reactance value was found to be 1 x 10.-7 and 1×10 -5 The diameter obtained after fitting to the arc between the points is taken as the interface resistance. The test process for the comparative example and other examples is the same as above.

[0208] 2) Coulombic efficiency test The coulombic test process is as follows: at 25°C, the fabricated battery is charged to 3.7 V (sodium iron pyrophosphate positive electrode) or 4.0 V (layered oxide positive electrode) at a constant current of 0.1 C to obtain the initial charge capacity (Cc1), and then discharged to 2.5 V at a constant current of 0.1 C to obtain the initial discharge capacity (Cd1), and then subjected to n charge and discharge cycles, and the number of cycles n until the capacity is reduced to 80% is recorded, and the average coulombic efficiency of the battery is calculated according to the following formula: Coulomb efficiency of the first cycle = initial discharge capacity (Cd1) / initial charge capacity (Cc1) × 100% Coulomb efficiency at nth cycle = discharge capacity at nth cycle (Cdn) / charge capacity at nth cycle (Ccn) × 100% The average value of the coulombic efficiencies from the second cycle to the nth cycle was taken as the average coulombic efficiency of the battery.

[0209] The test process for the comparative example and other examples is the same as above.

[0210] 3) Room temperature / low temperature cycle test until capacity retention is 80% room temperature / low temperature The cycle capacity retention test process was as follows: the fabricated full battery was charged at a constant current of 1C at 25°C and atmospheric pressure (0.1 MPa) until the voltage reached 4V (layered oxide cathode) or 3.7V (sodium iron pyrophosphate cathode), and then discharged at a constant current of 1C until the voltage reached 2.5V. 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 had decayed to 80%, the test was stopped and the number of cycles was recorded. The number of cycles required to achieve 80% capacity retention was used as an index for evaluating the full battery's cycle performance. The test process for the comparative example and other examples was the same as above.

[0211] 4) Rate performance test The test process for rate performance is as follows: The fabricated batteries were placed in a thermostatic chamber at 25°C and allowed to stand for 4 hours to reach a constant temperature. After reaching a constant temperature, the batteries were charged at 25°C at a constant current of 1C to 3.7V / 4V, then discharged at a constant current of 1C to 2.5V, cycled 5 times, and then allowed to stand for 5 minutes. Then, the batteries were charged at a constant current of 2C to 3.7V / 4V, cycled 5 times, and then allowed to stand for 5 minutes. Then, the batteries were discharged at a constant current of 2C to 2.5V, and then allowed to stand for 5 minutes. The 2C discharge capacity C2 was obtained. The charge and discharge current was then increased to nC, and the corresponding discharge capacity was recorded as Cn. The magnitude of the charge and discharge current when the rate R=Cn / C1×100% was just ≦50% was recorded.

[0212] 3. Analysis of the test results of each example and comparative example According to the above method, the batteries of each example and comparative example were manufactured, and the performance parameters of each item were measured. The results are shown in Tables 1, 2 and 3 below.

[0213] Table 1 [Table 1-1] [Table 1-2] [Table 1-3]

[0214] Table 2 [Table 2-1] [Table 2-2]

[0215] Table 3 [Table 3-1] [Table 3-2] [Table 3-3] [Table 3-4]

[0216] As can be seen from the above results, Examples 1 to 27 contain a solid electrolyte, and the contact angle of molten sodium on the surface of the solid electrolyte is smaller than 82°. As can be seen from a comparison between Examples 1 to 27 and Comparative Examples 1 to 9, compared with conventional solid electrolytes, the contact angle of molten sodium on the surface of the solid electrolyte in the present application is smaller than 82°, which is advantageous for reducing the interfacial resistance of the battery and improving the interfacial dynamics between the solid electrolyte and the positive electrode plate / negative electrode plate.

[0217] As can be seen from comparisons between Examples 1 to 5, 13 to 16, and 27 and Comparative Example 1, between Example 6 and Comparative Example 2, between Example 7 and Comparative Example 3, between Examples 8, 10, 17 to 18, and 21 to 26 and Comparative Example 4, between Example 9 and Comparative Example 5, between Example 11 and Comparative Example 6, between Example 12 and Comparative Example 7, between Example 19 and Comparative Example 8, and between Example 20 and Comparative Example 9, controlling the contact angle of molten sodium on the solid electrolyte surface to less than 82° for inorganic solid electrolytes and polymer solid electrolytes is advantageous in reducing the interfacial resistance of the battery and improving the number of cycles until the capacity retention of the battery at 25°C reaches 80%.

[0218] As can be seen from the comparison of Examples 1 to 5, 13 to 16, and 27 with Comparative Example 1, Example 6 with Comparative Example 2, Example 7 with Comparative Example 3, Example 11 with Comparative Example 6, and Example 12 with Comparative Example 7, 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O12 or Na 11 Sn2PS 12 For inorganic solid electrolytes, nanosecond laser, magnetron sputtering bias cleaning, or plasma cleaning can be used to treat the solid electrolyte, which is advantageous in reducing the interfacial resistance of the battery and improving the first-cycle Coulombic efficiency of the battery, the number of cycles required to reach 80% capacity retention at 25°C / -10°C, and rate performance.

[0219] As can be seen from comparisons between Examples 8, 10, 17-18, and 21-26 and Comparative Example 4, Example 9 and Comparative Example 5, Example 19 and Comparative Example 8, and Example 20 and Comparative Example 9, for NaFSI / PVDF-HFP, NaPF6 / PVDF-HFP, or NaPF6 / PEO polymer solid electrolytes, treating the surface of the solid electrolyte using a nanosecond laser, magnetron sputtering bias cleaning, or plasma cleaning is effective in reducing the interfacial resistance of the battery and improving the number of cycles required for the battery to achieve a capacity retention of 80% at 25°C.

[0220] As can be seen from the comparison of Examples 1 to 2, 4 to 5, 13 to 16, and 27 with Comparative Example 1, Example 6 with Comparative Example 2, Example 7 with Comparative Example 3, Example 11 with Comparative Example 6, and Example 12 with Comparative Example 7, 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 or Na 11 Sn2PS 12 For inorganic solid electrolytes, controlling the surface residual alkali content of the inorganic solid electrolyte so as not to exceed 1000 ppm is advantageous in reducing the interfacial resistance of the battery and improving the coulombic efficiency in the first cycle of the battery, the number of cycles until the capacity retention rate at 25°C / -10°C reaches 80%, and the rate performance.

[0221] As can be seen from the comparison of Examples 1, 5, 15-16, and 27 with Examples 2, 4, and 13-14, controlling the residual alkali content on the surface of the inorganic solid electrolyte so that it does not exceed 500 ppm is advantageous in further reducing the interfacial resistance of the battery and improving the rate performance of the battery.

[0222] As can be seen from the comparison of Examples 1, 4-5, 13, 15-16, and 27 with Comparative Example 1, Example 6 with Comparative Example 2, Example 7 with Comparative Example 3, Example 11 with Comparative Example 6, and Example 12 with Comparative Example 7, 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 or Na 11 Sn2PS 12 For inorganic solid electrolytes, XPS is used to test the inorganic solid electrolyte, and the amount of sodium elemental material present in the form of residual alkali is controlled to not exceed 10% based on the amount of detected sodium elemental material. This is advantageous in reducing the interfacial resistance of the battery and improving the coulombic efficiency at the first cycle of the battery, the number of cycles until the capacity retention rate at 25°C / -10°C reaches 80%, and the rate performance.

[0223] Comparisons of Examples 8, 10, 17, 21-22, and 24-26 with Comparative Example 4, Example 9 with Comparative Example 5, Example 19 with Comparative Example 8, and Example 20 with Comparative Example 9 reveal that when the NaFSI / PVDF-HFP, NaPF6 / PVDF-HFP, or NaPF6 / PEO polymer solid electrolyte is tested using XPS, the content of oxygen elemental substances present in the form of hydrogen-oxygen bonds, carbon-oxygen double bonds, and carbon-oxygen single bonds does not exceed 10% based on the amount of all detected elemental substances, which is advantageous for reducing the interfacial resistance of the battery and improving the first cycle / average coulombic efficiency of the battery, the number of cycles until the capacity retention rate reaches 80% at 25°C / -10°C, and rate performance.

[0224] As can be seen from a comparison between Examples 1 to 5 and Comparative Example 1, Example 6 and Comparative Example 2, Example 7 and Comparative Example 3, Examples 8 and 10 and Comparative Example 4, Example 9 and Comparative Example 5, Example 11 and Comparative Example 6, and Example 12 and Comparative Example 7, after treating the surface of the solid electrolyte with a nanosecond laser, the contact angle of molten sodium on the surface of the solid electrolyte is reduced to less than 82°, reducing the interfacial resistance of the battery and advantageously improving the number of cycles required to achieve a capacity retention rate of 80% at 25°C and the rate performance of the battery.

[0225] As can be seen from comparisons between Examples 13 to 16 and Comparative Example 1, Examples 17 to 18 and Comparative Example 4, Example 19 and Comparative Example 8, and Example 20 and Comparative Example 9, cleaning the surface of the solid electrolyte using magnetron sputtering bias reduces the contact angle of molten sodium on the surface of the solid electrolyte to less than 82°, which is advantageous in reducing the interfacial resistance of the battery and improving the number of cycles required for the battery to reach a capacity retention rate of 80% at 25°C.

[0226] As can be seen from a comparison between Example 27 and Comparative Example 1, and between Examples 21 to 26 and Comparative Example 4, after treating the surface of the solid electrolyte using plasma cleaning, the contact angle of molten sodium on the surface of the solid electrolyte is reduced to less than 82°, which is advantageous in reducing the interfacial resistance of the battery and improving the first cycle average coulombic efficiency of the battery and the number of cycles required to reach 80% capacity retention at 25°C / -10°C.

[0227] As can be seen from the comparison between Example 1 and Examples 6 and 7, after treating the surface of the inorganic solid electrolyte with a nanosecond laser, Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 or Na 11 Sn2PS 12 Compared to inorganic solid electrolytes, the amount of residual alkalinity before and after surface treatment of the β-Na2O·11Al2O3 inorganic solid electrolyte is reduced to a greater extent, which is advantageous in significantly improving the battery's first cycle / average coulombic efficiency and the number of cycles required to achieve an 80% capacity retention rate at 25°C / -10°C.

[0228] As can be seen from the comparison of Example 6 with Examples 1 and 7, after treating the surface of the inorganic solid electrolyte with a nanosecond laser, 11 Sn2PS 12 Compared to inorganic solid electrolytes, Na 3.4 Zr 1.9 Zn 0.1 Si 2.2 P 0.8 O 12 The amount of residual alkali on the surface of the inorganic solid electrolyte is smaller than that of the inorganic solid electrolyte, which is advantageous in further reducing the interface resistance of the battery.

[0229] As can be seen from a comparison between Example 8 and Example 9, after treating the surface of the polymer solid electrolyte using a nanosecond laser, the polymer solid electrolyte containing a 60% mass content of sodium salt had a lower content of oxygen elements in the forms of OH, C=O, and CO than the polymer solid electrolyte containing a 30% mass content of sodium salt, which further reduced the interfacial resistance of the battery and was advantageous in improving the first cycle / average coulombic efficiency of the battery, the number of cycles until the capacity retention rate reached 80% at 25°C / -10°C, and rate performance.

[0230] As can be seen from the comparison between Example 17 and Example 18, for a NaFSI / PVDF-HFP polymer solid electrolyte, cleaning the surface of the solid electrolyte using magnetron sputtering bias and controlling the gas atmosphere of the magnetron sputtering bias cleaning treatment to argon gas is advantageous in further reducing the interfacial resistance of the battery and improving the first cycle / average coulombic efficiency of the battery, the number of cycles until the capacity retention rate at 25°C / -10°C reaches 80%, and the rate performance.

[0231] As can be seen from the comparison between Examples 22 and 21, for the NaFSI / PVDF-HFP polymer solid electrolyte, the surface of the solid electrolyte was treated using plasma cleaning, and the gas atmosphere for the plasma cleaning treatment was helium gas, which is advantageous in further reducing the interfacial resistance of the battery and improving the first cycle average coulombic efficiency of the battery and the number of cycles required to reach 80% capacity retention at 25°C / -10°C.

[0232] As can be seen from a comparison between Examples 1 and 27 and Example 13, for a β-Na2O·11Al2O3 inorganic solid electrolyte, treating the inorganic solid electrolyte with a nanosecond laser or plasma cleaning is advantageous in reducing the interfacial resistance of the battery and improving the battery's average Coulombic efficiency, the number of cycles required to reach 80% capacity retention at 25°C / -10°C, and rate performance compared to cleaning the surface of the inorganic solid electrolyte with bias magnetron sputtering. As can be seen from a comparison between Examples 1 and 27, for a β-Na2O·11Al2O3 inorganic solid electrolyte, treating the inorganic solid electrolyte with a nanosecond laser is advantageous in reducing the interfacial resistance of the battery and improving the battery's first cycle / average Coulombic efficiency and the number of cycles required to reach 80% capacity retention at 25°C / -10°C compared to cleaning the surface of the inorganic solid electrolyte with plasma cleaning.

[0233] As can be seen from a comparison between Examples 8 and 22 and Example 17, for a NaFSI / PVDF-HFP polymer solid electrolyte, treating the polymer solid electrolyte with a nanosecond laser or plasma cleaning is advantageous in reducing the interfacial resistance of the battery and improving the first cycle / average Coulombic efficiency, the number of cycles until 80% capacity retention at 25°C / -10°C, and the rate performance, compared to cleaning the surface of the polymer solid electrolyte with a magnetron sputtering bias. As can be seen from a comparison between Example 22 and Example 8, treating the NaFSI / PVDF-HFP polymer solid electrolyte with plasma cleaning is advantageous in reducing the interfacial resistance of the battery and improving the first cycle / average Coulombic efficiency, the number of cycles until 80% capacity retention at 25°C, and the rate performance, compared to cleaning the surface of the polymer solid electrolyte with a nanosecond laser.

[0234] As can be seen from the comparison between Example 1 and Examples 11 and 12, after treating the surface of the inorganic solid electrolyte with a nanosecond laser, Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 ) Na coated with O2 or ZrO2, TiO2 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 Compared to using O2 as the positive electrode active material, using Na4Fe3(PO4)2P2O7 as the positive electrode active material is advantageous in reducing the interfacial resistance of the battery and improving the first cycle / average coulombic efficiency of the battery, the number of cycles until the capacity retention rate at 25°C / -10°C reaches 80%, and the rate performance.

[0235] As can be seen from the comparison between Example 12 and Example 11, after treating the surface of the inorganic solid electrolyte with a nanosecond laser, 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 Using O2 as a positive electrode active material is advantageous in improving the first cycle / average coulombic efficiency of the battery and the number of cycles required to reach 80% capacity retention at 25°C / -10°C.

[0236] As can be seen from the comparison between Example 17 and Examples 19 and 20, the surface of the polymer solid electrolyte was cleaned using magnetron sputtering bias, and then Na(Cu 1 / 9 Ni 2 / 9 Fe 1 / 3 Mn 1 / 3 ) Na coated with O2 or ZrO2, TiO2 2 / 3 Ni 1 / 6 Mn 2 / 3 Cu 1 / 9 Mg 1 / 18 Compared with using O2 as the positive electrode active material, using Na4Fe3(PO4)2P2O7 as the positive electrode active material is advantageous in improving the first cycle coulombic efficiency of the battery and the number of cycles required to reach 80% capacity retention at 25°C / -10°C.

[0237] As can be seen from the comparison between Example 20 and Example 19, the surface of the polymer solid electrolyte was cleaned using magnetron sputtering bias, and then 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 Using O2 as the positive electrode active material is advantageous in improving the first cycle / average coulombic efficiency of the battery and the number of cycles required for the capacity retention at 25°C to reach 80%.

[0238] As can be seen from the examples, excessively high laser power, pulse time, or cleaning time can further reduce the residual alkali content or oxygen-containing functional group content, contributing to improving the interfacial performance, but excessively high energy will damage the solid electrolyte body material and further reduce the cycle performance of the battery.

[0239] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and any embodiment that has substantially the same configuration as the technical idea and achieves the same effects within the scope of the technical solution of the present application is included within the technical scope of the present application. In addition, various modifications that a person skilled in the art can make to the embodiments and other methods configured by combining some of the components of the embodiments are also included within the scope of the present application, as long as they do not deviate from the spirit of the present application. [Explanation of symbols]

[0240] 1: battery pack, 2: upper housing, 3: lower housing, 4: battery module, 5: secondary battery, 51: case, 52: electrode assembly, 53: cover plate.

Claims

1. 1. A solid electrolyte for a sodium secondary battery, characterized in that a contact angle of molten sodium on a surface of the solid electrolyte is smaller than 82°.

2. 2. The solid electrolyte of claim 1, wherein the solid electrolyte comprises an inorganic solid electrolyte or a polymer solid electrolyte.

3. 3. The solid electrolyte according to claim 2, wherein the mass content of residual alkali in the inorganic solid electrolyte does not exceed 1000 ppm, and optionally does not exceed 500 ppm, based on the total mass of the inorganic solid electrolyte.

4. 4. The solid electrolyte according to claim 2 or 3, characterized in that the inorganic solid electrolyte is tested using X-ray photoelectron spectroscopy (XPS), and the content of the amount of substance of sodium element present in the form of residual alkali does not exceed 10% based on the amount of substances of all elements detected.

5. 5. The solid electrolyte of claim 2, wherein the inorganic solid electrolyte comprises one or more of a sulfur-based electrolyte, a sodium fast ion conductor, and an oxide electrolyte.

6. The sulfur-based electrolyte is a glassy Na ２ S-P ２ S ５ , Na １１ Sn ２ PnX １２ , Na ３ Pn ｙ Pn' １－ｙ X ｚ X' ４－ｚ wherein Pn comprises at least one of P and Sb, X comprises at least one of S and Se, Pn′ comprises at least one of Si, Sn and Ge, and X′ comprises at least one of F, Br and Cl, and 0<y≦1, 0<z≦4; The sodium fast ion conductor is Na ３＋ｘ M ｙ M' ２－ｙ Si ２－ｚ P ｚ O １２ wherein M and M′ each independently comprise at least one of Zr, Ca, Mg, Zn, La, Ti, and Nb, and 0≦x≦1, 0<y≦2, and 0≦z<2; The oxide electrolyte is Na-β-Al ２ O ３ , Na-β″-Al ２ O ３ and the Na-β-Al ２ O ３ is β-Na ２ O.11Al ２ O ３ and the Na-β″-Al ２ O ３ is β″-Na ２ O.5Al ２ O ３ Optionally, the oxide electrolyte further comprises an inorganic oxide, and the inorganic oxide comprises Li ２ O, MgO, TiO ２ , ZrO ２ , Y ２ O ３ , MnO ２ , SiO ２ , Fe ２ O ３ and the mass content of the inorganic oxide is 0.5% to 30% based on the total mass of the oxide electrolyte.

7. 3. The solid electrolyte according to claim 2, wherein the polymer solid electrolyte is tested using X-ray photoelectron spectroscopy (XPS), and based on the amount of substances of all detected elements, the content of substances of oxygen element present in the form of hydrogen-oxygen bond, carbon-oxygen double bond, and carbon-oxygen single bond does not exceed 10%.

8. 8. The solid electrolyte according to claim 2, wherein the polymer solid electrolyte comprises a sodium salt and a polymer, and optionally comprises a plasticizer and / or an inorganic filler.

9. 9. The solid electrolyte according to claim 8, wherein the sodium salt comprises one or more of sodium chloride, sodium bromide, sodium nitrate, sodium perchlorate, sodium hexafluorophosphate, sodium tetrafluoroborate, sodium tetrafluoroyttriate, sodium hexafluoroarsenate, sodium acetate, sodium trifluoroacetate, sodium tetraphenylborate, sodium trifluoromethanesulfonate, sodium bis(fluorosulfonyl)imide, sodium bis(trifluoromethylsulfonyl)imide, and sodium (normal perfluorobutylsulfonyl)imide, and optionally comprises one or more of sodium hexafluorophosphate and sodium bis(fluorosulfonyl)imide.

10. 10. The solid electrolyte according to claim 8 or 9, wherein the polymer comprises one or more of polyethylene oxide, polyethylene glycol, polyvinylpyrrolidone, polymethyl methacrylate, polyvinylidene fluoride, poly(vinylidene fluoride-co-hexafluoropropylene), polyvinyl alcohol, polyacrylonitrile, polyvinyl chloride, polyacrylamide, polytrimethylene carbonate, and perfluoropolyether.

11. 11. The solid electrolyte according to claim 8, wherein the polymer solid electrolyte comprises a salt-in-polymer electrolyte, and a mass content of the sodium salt in the salt-in-polymer electrolyte is greater than 50% and less than 100%, based on the total mass of the salt-in-polymer electrolyte.

12. 12. The solid electrolyte of claim 8, wherein the polymer solid electrolyte comprises a polymer-in-salt electrolyte, and the mass content of sodium salt in the polymer-in-salt electrolyte is 5% to 50%, based on the total mass of the polymer-in-salt electrolyte.

13. 13. The solid electrolyte according to claim 1, wherein the solid electrolyte is a surface-treated electrolyte, and the surface treatment method includes one or more of a nanosecond laser treatment, a magnetron sputtering bias cleaning treatment, and a plasma cleaning treatment.

14. 14. The solid electrolyte of claim 13, wherein the nanosecond laser treatment atmosphere comprises air, the laser wavelength is 250 nm to 3000 nm, optionally 250 nm to 1200 nm, the average laser power is 5 W to 30 W, optionally 10 W to 30 W, the repetition frequency is 5 kHz to 40 kHz, the scanning frequency is 20 mm / s to 150 mm / s, and the pulse duration is 10 ns to 100 ns, optionally 50 ns to 100 ns.

15. The atmosphere of the magnetron sputtering bias cleaning treatment includes vacuum, argon gas, or oxygen gas, and the pressure of the vacuum atmosphere is 10 －４ 15. The solid electrolyte according to claim 13, wherein the pressure of the argon gas or oxygen gas atmosphere is 0.4 Pa to 0.8 Pa, the bias power is 60 W to 100 W, the bias cleaning time is 5 min to 60 min, and the temperature is 20° C. to 150° C.

16. The atmosphere of the plasma cleaning treatment includes air, vacuum, argon gas, nitrogen gas, or helium gas, and the pressure of the vacuum atmosphere is 10 －４ The pressure of the argon gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the nitrogen gas atmosphere is 0.2 Pa to 1 Pa, the pressure of the helium gas atmosphere is 0.2 Pa to 1 Pa, the cleaning power of the plasma cleaning process is 100 W to 3000 W, and the cleaning frequency is 10 －３ 16. The solid electrolyte according to claim 13, wherein the frequency is from 1000 MHz to 3000 MHz and the cleaning time is from 0.1 min to 10 min.

17. 17. The solid electrolyte according to claim 13, wherein the solid electrolyte is an oxide electrolyte, and the surface treatment method is nanosecond laser treatment.

18. A secondary battery comprising the solid electrolyte according to any one of claims 1 to 17.

19. 19. The secondary battery according to claim 18, wherein the secondary battery is a sodium secondary battery.

20. 20. The secondary battery according to claim 18, wherein the secondary battery is a sodium secondary battery having no negative electrode.

21. 21. The secondary battery according to claim 18, wherein the secondary battery includes a positive electrode plate, the positive electrode plate includes a positive electrode active material, and the positive electrode active material includes at least one of a layered oxide, a polyanion-type compound, and a Prussian blue compound.

22. The positive electrode active material is 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 22. The secondary battery according to claim 21, comprising one or more of:

23. The surface of the positive electrode active material has a coating layer, and the coating layer contains a carbon material, ZrO ２ , TiO ２ , 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.

24. 24. The secondary battery according to claim 23, wherein the thickness of the coating layer is 2 nm to 1000 nm, and optionally 10 nm to 100 nm.

25. 25. The secondary battery according to claim 18, wherein the secondary battery includes a negative electrode plate, the negative electrode plate including a negative electrode current collector and an undercoating disposed on at least one surface of the negative electrode current collector, the undercoating including one or more of carbon nanotubes, graphite, graphene, silver composite carbon nanoparticles, and tin composite carbon nanoparticles.

26. The areal density of the undercoating is 5 g / m ２ ~50g / m ２ 26. The secondary battery according to claim 25, wherein

27. 27. The secondary battery according to claim 26, wherein the undercoating has a thickness of 2 μm to 100 μm.

28. 28. The secondary battery according to claim 18, wherein the interface resistance of the secondary battery is less than 100 Ω.

29. A battery module comprising the secondary battery according to any one of claims 18 to 28.

30. A battery pack comprising the secondary battery according to any one of claims 18 to 28 or the battery module according to claim 29.

31. 31. A power consuming device comprising at least one of the secondary battery according to claim 18, the battery module according to claim 29, and the battery pack according to claim 30.

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