Solid-state electrolyte material, solid-state electrolyte and positive electrode material and preparation methods therefor, and sodium-ion battery

Abstract

The present invention relates to the field of sodium-ion batteries. Disclosed are a solid-state electrolyte material, a solid-state electrolyte and a positive electrode material and preparation methods therefor, and a sodium-ion battery. As obtained from an XRD pattern of the solid-state electrolyte material, the ratio of the peak intensity I(020) of the (020) crystal face to the peak intensity I(421) of the (421) crystal face satisfies 0.9≤I(020) / I(421)<1, and the ratio of the peak area A(020) of the (020) crystal face to the peak area A(421) of the (421) crystal face satisfies 0.45≤A(020) / A(421)<1. The solid-state electrolyte material has good crystallinity, high ionic conductivity and good structural stability. A positive electrode material prepared from the solid-state electrolyte material has relatively high capacity and good rate performance, cycle performance and thermal stability.

Description

Solid electrolyte material, solid electrolyte, positive electrode material and preparation method thereof, and sodium ion battery

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Chinese patent application 202310788122.0 filed on June 29, 2023, the contents of which are incorporated herein by reference. Technical Field

[0003] The present invention relates to the field of sodium ion batteries, and in particular to solid electrolyte materials, solid electrolytes, positive electrode materials and preparation methods thereof, and sodium ion batteries. Background Art

[0004] Lithium-ion secondary batteries offer advantages such as high specific energy density, a wide operating temperature range, long charge-discharge life, low self-discharge, and minimal memory effect. Their mass energy density can reach 270Wh / kg, making them considered the most promising chemical power source. Since Sony commercialized them in 1990, they have not only dominated the field of small mobile consumer electronics such as laptop computers, mobile phones, camcorders, digital cameras, and MP3 players, but have also shown remarkable development prospects in recent years in the fields of power batteries and energy storage batteries.

[0005] However, lithium resources are scarce on Earth, with an abundance of only 0.0065% in the Earth's crust and an uneven distribution. With the advent of electric vehicles and smart grids, lithium resource shortages and high costs will inevitably become significant constraints to their development. Therefore, the development of novel energy storage battery systems is essential. Sodium, with an abundance of 2.64% in the Earth's crust, is low-cost, and sodium ions share a similar intercalation mechanism to lithium ions. Consequently, sodium-ion secondary batteries have recently attracted renewed attention.

[0006] However, most reported sodium battery research is based on liquid electrolytes containing organic solvents, such as ethers and carbonates. The flammability and leakage of organic solvents present potential safety issues in liquid sodium batteries. In contrast, solid-state sodium batteries offer advantages such as high stability, no leakage risk, and easy direct stacking, significantly improving battery safety.

[0007] In solid-state battery systems, one of the most critical materials is the solid electrolyte. Solid-state electrolytes include organic polymers, sulfides, halides, perovskites, NASICONs, and garnets. NASICONs offer advantages such as high conductivity, excellent thermal stability, and a wide electrochemical window, making them one of the solid-state electrolytes with the greatest potential for industrialization.

[0008] The theoretical ionic conductivity of NASICON solid electrolyte can reach 10-3 S / cm, but the data reported in current studies are generally lower than 0.5×10 -3 S / cm, so its ionic conductivity still has a lot of room for improvement. Secondly, problems such as poor compatibility at the electrode-electrolyte interface limit its practical application. NASICON-type solid electrolytes have problems of structural instability and easy phase separation after nano-sizing, which is not conducive to the long-term preservation of nano-slurries. In addition, in order to effectively improve its ionic conductivity, researchers have mostly used wet chemical reaction methods such as hydrothermal method and sol-gel method to improve its performance, which cannot be produced at low cost and on a large scale. Traditional solid-phase reactions are very likely to cause the formation of impurities due to uneven mixing of raw materials. On the other hand, the residual sodium content on the surface of the mainstream sodium-based layered positive electrode materials in the market is too high, which affects the diffusion and transport of sodium ions, destroys the material structure, and leads to reduced battery cycle life and energy efficiency, and poor safety.

[0009] Summary of the Invention

[0010] The purpose of the present invention is to overcome the problems of low ion conductivity and poor structural stability of existing solid electrolyte materials.

[0011] In order to achieve the above object, the first aspect of the present invention provides a solid electrolyte material, wherein the peak intensity I of the (020) crystal plane obtained by XRD is (020) The peak intensity I of (421) crystal plane (421) The ratio satisfies 0.9≤I (020) / I (421) <1;

[0012] The peak area A of the (020) crystal plane of the solid electrolyte material obtained by XRD (020) The peak area A of (421) crystal plane (421) The ratio satisfies 0.45≤A (020) / A (421) <1.

[0013] A second aspect of the present invention provides a method for preparing the solid electrolyte material according to the first aspect, the method comprising the following steps:

[0014] (1) In the presence of a solvent, a Na source, a Zr source, a Si source, and a P source are mixed to obtain a mixture A; optionally, the mixture A further contains M 1 Source and / or M 2 source;

[0015] (2) heating a mixture B containing the mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I;

[0016] (3) pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II;

[0017] (4) The solid electrolyte precursor II is sintered and crushed in sequence.

[0018] A third aspect of the present invention provides a solid electrolyte, which comprises the solid electrolyte material described in the first aspect, a polymer and a sodium salt.

[0019] A fourth aspect of the present invention provides a method for preparing the solid electrolyte according to the third aspect, the method comprising:

[0020] (a) mixing a solid electrolyte material, a polymer and a sodium salt to obtain a mixture;

[0021] (b) subjecting the mixture to autoclaving.

[0022] A fifth aspect of the present invention provides a positive electrode material, comprising a positive electrode active substance and a solid electrolyte material coated on the surface of the positive electrode active substance, wherein the solid electrolyte material is the solid electrolyte material described in the first aspect.

[0023] A sixth aspect of the present invention provides a method for preparing the positive electrode material according to the fifth aspect, the method comprising:

[0024] The mixture containing the solid electrolyte material and the positive electrode active material is heat-treated at 300-750° C.; wherein the solid electrolyte material is the solid electrolyte material described in the first aspect.

[0025] A seventh aspect of the present invention provides a sodium ion battery, comprising the solid electrolyte material as described in the first aspect or the positive electrode material as described in the fifth aspect.

[0026] Through the above technical solution, the present invention has the following advantages:

[0027] (1) The solid electrolyte material provided by the present invention has a peak intensity of (020) crystal plane obtained by XRD. (020) The peak intensity I of (421) crystal plane (421) The ratio satisfies 0.9≤I (020) / I (421) <1; the peak area A of the (020) crystal plane obtained by XRD (020) The peak area A of (421) crystal plane (421) The ratio satisfies 0.45≤A (020) / A (421)<1. The peak intensity and peak area ratio of the (020) crystal plane and the (421) crystal plane of the solid electrolyte material are within the above-mentioned specific range, so that the solid electrolyte material has good crystallinity, thereby ensuring that the microstructure of the prepared solid electrolyte material is highly dense, free of pores and microcracks, and has a monoclinic phase structure, thereby improving its ionic conductivity; preferably, by doping the solid electrolyte material with elements, the sintering temperature of the material can be reduced, while the stability and ionic conductivity of the material can be improved;

[0028] (2) The method for preparing solid electrolyte materials provided by the present invention is to introduce doping elements during the mixing process to achieve uniform mixing of the elements and the main phase at the atomic level; combined with the subsequent polymerization reaction of the mixture A with the organic monomer and the pre-sintering, sintering and crushing treatment, and preferably, by regulating the values ​​of x, y, and z to control the content of Na, Zr, Si, P and doping elements, as well as the process conditions of the dry preparation process, the lattice constant is comprehensively regulated, and the prepared solid electrolyte material has uniform composition, high ionic conductivity, and an average particle size that can reach the nanometer level. The presence of doping elements inside the lattice makes its structural stability excellent, and its nanoscale slurry can maintain a pure phase state for a long time without phase decomposition. In addition, the prepared nanoscale solid electrolyte slurry and powder have a high specific surface area and a strong specific surface energy; furthermore, the method has the advantages of easy availability of raw materials, low cost, simple preparation method, and easy industrial large-scale mass production;

[0029] (3) In the positive electrode material provided by the present invention, the solid electrolyte material is coated on the surface of the positive electrode active material and is evenly distributed. Preferably, the positive electrode material is subjected to acid-base titration treatment, and a relatively obvious characteristic titration peak appears in the pH range of 5-8, indicating that the coating of the NASICON-type solid electrolyte material can broaden the diffusion channel of sodium ions, so that the positive electrode material has a higher capacity, excellent rate, cycle and thermal stability.

[0030] (4) The method for preparing the positive electrode material provided by the present invention consumes the residual sodium on the surface of the positive electrode active material by coating the NASICON type solid electrolyte material on the surface. At the same time, the NASICON type solid electrolyte material has a three-dimensional sodium ion diffusion channel, which can be widened after coating, thereby improving the electrochemical performance of the sodium ion battery. Secondly, the structurally stable NASICON type solid electrolyte material has excellent thermal stability, which can improve the safety of the positive electrode material. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] FIG1 is an XRD spectrum of the solid electrolyte material prepared in the preparation example and the comparative preparation example;

[0032] FIG2 is an XRD spectrum of the solid electrolyte material prepared in the preparation example and the comparative preparation example after abuse testing. DETAILED DESCRIPTION

[0033] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0034] In the present invention, unless otherwise specified, the room temperature and normal temperature refer to 25±2°C.

[0035] In the present invention, unless otherwise specified, the term "optionally" refers to performing or not performing the operation, or adding or not adding the material.

[0036] As mentioned above, the first aspect of the present invention provides a solid electrolyte material, wherein the peak intensity I of the (020) crystal plane obtained by XRD is (020) The peak intensity I of (421) crystal plane (421) The ratio satisfies 0.9≤I (020) / I (421) <1;

[0037] The peak area A of the (020) crystal plane of the solid electrolyte material obtained by XRD (020) The peak area A of (421) crystal plane (421) The ratio satisfies 0.45≤A (020) / A (421) <1.

[0038] During the research process, the inventors of the present invention found that the peak intensity and peak area of ​​the (020) crystal plane obtained by XRD, as well as the peak intensity and peak area of ​​the (421) crystal plane obtained by XRD of the NASICON-type solid electrolyte material meet the above requirements, can regulate its crystal structure, and the peak intensity and peak area show suitable crystallinity and good structural stability, change the oxygen atom bond length, weaken the interaction between Na and O, reduce the migration potential energy of carriers, increase the carrier concentration, and thus improve its ionic conductivity.

[0039] According to some embodiments of the present invention, preferably, 0.97≤I (020) / I (421) <1;

[0040] According to some embodiments of the present invention, preferably, 0.46≤A (020) / A(421) <1.

[0041] The adoption of the above preferred embodiment is conducive to further improving the ionic conductivity of the solid electrolyte material and improving the structural stability.

[0042] According to some embodiments of the present invention, preferably, the solid electrolyte material has a structure shown in Formula I: Na 3+x [Zr 2-y M 1 y ][Si 2-z M 2 z ]PO 12 Formula I;

[0043] Among them, 0≤x<1.15, 0≤y≤0.5, 0≤z≤1; M 1 is at least one of Mg, La, Y, Al, and Ca; M 2 It is at least one of Ga, In, Ge and Sc.

[0044] According to some embodiments of the present invention, preferably, the average particle size D of the solid electrolyte material is 50 The nanoscale slurry of the solid electrolyte material can be left standing for a long time without precipitation, phase decomposition or the like.

[0045] According to some embodiments of the present invention, preferably, the ionic conductivity of the solid electrolyte material is greater than 8×10 -5 S / cm, preferably greater than 1×10 -4 S / cm.

[0046] A second aspect of the present invention provides a method for preparing the solid electrolyte material according to the first aspect, the method comprising the following steps:

[0047] (1) In the presence of a solvent, a Na source, a Zr source, a Si source, and a P source are mixed to obtain a mixture A; optionally, the mixture A further contains M 1 Source and / or M 2 source;

[0048] (2) heating a mixture B containing the mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I;

[0049] (3) pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II;

[0050] (4) The solid electrolyte precursor II is sintered and crushed in sequence.

[0051] According to some embodiments of the present invention, preferably, in step (1), the solvent is selected from at least one of water, N-methyl-2-pyrrolidone, phthalate, dibasic lipid, long-chain alcohol and pyrrolidone, preferably water.

[0052] According to some embodiments of the present invention, preferably, in step (1), the Na source is selected from at least one of oxides, hydroxides, nitrates, oxalates, organic alcohol salts and carbonates containing Na, and is preferably sodium carbonate.

[0053] According to some embodiments of the present invention, preferably, in step (1), the Zr source is selected from at least one of oxides, hydroxides, nitrates, oxalates, organic alcohol salts and carbonates containing Zr, preferably at least one of ZrO2, zirconium silicate and zirconium tetrachloride, more preferably ZrO2.

[0054] According to some embodiments of the present invention, preferably, in step (1), the Si source is selected from at least one of oxides, hydroxides, nitrates, oxalates, organic alcohol salts and carbonates containing Si, preferably at least one of SiO2, sodium silicate and silicon carbide, more preferably SiO2.

[0055] According to some embodiments of the present invention, preferably, in step (1), the P source is at least one of NH4H2PO4, sodium dihydrogen phosphate and phosphoric acid, preferably NH4H2PO4.

[0056] According to some embodiments of the present invention, preferably, in step (1), the M 1 Source and the M 2 The sources are each independently selected from the group consisting of 1 and / or M 2 At least one of oxides, hydroxides, nitrates, oxalates, organic alcohol salts and carbonates; preferably, the M 1 The source is Y2O3 and / or La2O3; preferably, the M 2 The source is at least one of Sc2O3, Ga2O3 and GeO2.

[0057] According to some embodiments of the present invention, preferably, in step (1), the ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65-1.725; when the mixture A further contains M 2 When the Na source is used, the molar amount of Na in the Na source is equal to the molar amount of Si in the Si source and the molar amount of M 2 Source M 2The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65-1.725.

[0058] According to some embodiments of the present invention, preferably, in step (1), the Na source, the Zr source, the Si source, the P source, the M 1 Source and the M 2 The amount of the source is such that the obtained solid electrolyte material has the structure shown in Formula I. The specific structure is as described above and will not be described here. 1 Source and the M 2 The molar amount of the source satisfies the stoichiometric ratio of the structure shown in Formula I.

[0059] According to some embodiments of the present invention, preferably, in step (1), the solid content of the mixture A at 25° C. is 40-60 wt %.

[0060] According to some embodiments of the present invention, preferably, in step (1), the mixing can be carried out in a conventional device having mixing and / or crushing functions, without particular limitation, for example, it can be carried out in a planetary ball mill or a high-energy ball mill.

[0061] According to some embodiments of the present invention, preferably, in step (2), the organic monomer is selected from at least one of acrylamide (AM), methylenebisacrylamide (MBAM), styrene, butadiene and methyl methacrylate, preferably acrylamide.

[0062] According to some embodiments of the present invention, preferably, in step (2), the initiator is selected from at least one of benzoyl peroxide, (NH4)2S2O8 and K2S2O8, preferably (NH4)2S2O8.

[0063] According to some embodiments of the present invention, preferably, in step (2), the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED).

[0064] According to some embodiments of the present invention, preferably, in step (2), the mass ratio of the mixture A to the organic monomer is 1:0.5-0.6.

[0065] According to some embodiments of the present invention, preferably, in step (2), the mass ratio of the organic monomer, the initiator and the catalyst is 1:0.5-1.5:0.5-1.5.

[0066] According to some embodiments of the present invention, preferably, in step (2), the polymerization reaction conditions include: polymerization temperature of 80-200° C., and polymerization time of 10-15 h.

[0067] According to some embodiments of the present invention, preferably, in step (3), the pre-sintering conditions include: a pre-sintering temperature of 300-700° C., and a pre-sintering time of 2-6 hours.

[0068] According to some embodiments of the present invention, preferably, in step (3), the average particle size D of the solid electrolyte precursor II is 50 1-50 μm, preferably 40-50 μm.

[0069] According to some embodiments of the present invention, preferably, in step (4), the sintering conditions include: a sintering temperature of 1000-1200° C. and a sintering time of 4-10 h. The above preferred embodiment is advantageous for synthesizing monoclinic solid electrolyte materials.

[0070] According to some embodiments of the present invention, preferably, the method further comprises: in the presence of water, subjecting the product obtained by the crushing treatment in step (4) to nano-processing to obtain a nano-scale solid electrolyte material. The above preferred embodiment is advantageous in obtaining an average particle size D 50 Nanoscale solid electrolyte materials that meet the above requirements.

[0071] Preferably, the nano-processing step comprises: sand-milling the product obtained by the crushing process in step (4) in the presence of water to obtain a nano-scale slurry, wherein the solid content of the nano-scale slurry at 25°C is 40-60wt%; then drying the nano-scale slurry, and grinding the obtained dried product. Preferably, the sand-milling conditions are: a rotation speed of 800-1200r / min and a time of 1-3 hours; preferably, the drying method is at least one of forced air drying, vacuum drying and freeze drying; the drying conditions include: a temperature of 25-60°C and a time of 8-12h; and the grinding is performed using a jet mill.

[0072] A third aspect of the present invention provides a solid electrolyte, which comprises the solid electrolyte material described in the first aspect, a polymer and a sodium salt.

[0073] According to some embodiments of the present invention, preferably, the polymer is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polydimethylsiloxane, polymethyl methacrylate, polypropylene carbonate, polyethylene carbonate and polycaprolactone, preferably polyethylene oxide (PEO).

[0074] According to some embodiments of the present invention, preferably, the sodium salt is selected from at least one of NaTFSI, sodium hexafluorophosphate, sodium perchlorate and sodium trifluoromethanesulfonate, preferably NaTFSI.

[0075] According to some embodiments of the present invention, preferably, based on the total mass of the solid electrolyte, the content of the solid electrolyte material is 5-30 wt%, the content of the polymer is 50-75 wt%, and the content of the sodium salt is 15-30 wt%.

[0076] According to some embodiments of the present invention, preferably, the solid electrolyte is a membrane structure, and the thickness of the membrane structure is 5-200 μm, preferably 20-100 μm.

[0077] A fourth aspect of the present invention provides a method for preparing the solid electrolyte according to the third aspect, the method comprising:

[0078] (a) mixing a solid electrolyte material, a polymer and a sodium salt to obtain a mixture;

[0079] (b) subjecting the mixture to autoclaving.

[0080] According to some embodiments of the present invention, preferably, the mixing conditions in step (a) include: a mixing temperature of 0.5-1.5T m , where T m is the softening temperature of the polymer; the rotation speed is 300-500 rpm, and the mixing time is when the torque of the mixer reaches a stable state.

[0081] According to some embodiments of the present invention, preferably, the hot pressing conditions in step (b) include: a hot pressing temperature of 60-80°C, a hot pressing pressure of 1-10 MPa, and a hot pressing time of 5-20 minutes. The hot pressing pressure can be adjusted according to the desired thickness of the solid electrolyte membrane. There are no particular limitations on the equipment used for the hot pressing process, and the equipment can be, for example, selected from at least one of a flat plate hot press, a roller hot press, and a pulse hot press.

[0082] According to some embodiments of the present invention, preferably, the method further comprises: drying the hot-pressed product obtained by the hot-pressing treatment in step (b), and the drying conditions include: drying temperature of 60-120° C. and drying time of 4-24 h.

[0083] A fifth aspect of the present invention provides a positive electrode material, comprising a positive electrode active substance and a solid electrolyte material coated on the surface of the positive electrode active substance, wherein the solid electrolyte material is the solid electrolyte material described in the first aspect.

[0084] According to some embodiments of the present invention, preferably, the mass ratio of the solid electrolyte material to the positive electrode active material is 0.05-1:100, preferably 0.5-0.8:100.

[0085] According to some embodiments of the present invention, preferably, the positive electrode active material is NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2 and at least one of the layered oxide positive electrode materials derived therefrom. Wherein, the layered oxide positive electrode material derived therefrom is NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2 and / or Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2 is doped with elements and / or the element ratio is adjusted to obtain a layered oxide positive electrode material, such as but not limited to Na 0.45 Ni 0.22 Co 0.11 Mn 0.66 O2, Na[Ni 0.25 Fe 0.5 Mn 0.25 ]O2、NaNi 0.25 Fe 0.25 Co 0.25 Mn 0.25 At least one of O2.

[0086] According to some embodiments of the present invention, preferably, the cathode material undergoes acid-base titration treatment and exhibits a characteristic titration peak between pH = 5 and 8. This indicates that the solid electrolyte material provided by the present invention generates Na3PO4 at the interface with the cathode active material during the coating process. Na3PO4 is a fast ion conductor and can serve as a buffer layer to balance the potential difference between the NASICON solid electrolyte material and the cathode active material, alleviate the generation of the space charge layer, and reduce the interfacial impedance, thereby facilitating better performance of the electrochemical properties of the cathode material.

[0087] According to some embodiments of the present invention, preferably, in the differential scanning calorimetry analysis spectrum of the positive electrode material, the onset temperature of the main exothermic peak is above 290°C. The onset temperature of the main exothermic peak of the positive electrode material is significantly delayed, indicating that the solid electrolyte material provided by the present invention can improve the thermal stability of the resulting positive electrode material after being coated on the surface of the positive electrode active material.

[0088] The positive electrode material can improve structural stability, improve the oxygen evolution problem under high sodium desorption conditions, and reduce the degree of side reactions between the positive electrode material and the electrolyte under high voltage conditions, thereby improving the electrochemical performance and safety of sodium ion batteries.

[0089] A sixth aspect of the present invention provides a method for preparing the positive electrode material according to the fifth aspect, the method comprising:

[0090] The mixture containing the solid electrolyte material and the positive electrode active material is heat-treated at 300-750° C.; wherein the solid electrolyte material is the solid electrolyte material described in the first aspect.

[0091] According to some embodiments of the present invention, preferably, the mixture is obtained by mixing a solid electrolyte material and a positive electrode active material in a mixing device; the mixing device can be, for example, a ball mill, a high-speed mixer, a vertical mixer, a horizontal mixer, an inclined mixer, or other conventional dry mixing equipment, without particular limitation. Preferably, the heating device for the heat treatment can be, for example, a tubular furnace, an oxygen furnace, a muffle furnace, a roller kiln, or other conventional sintering and heat treatment equipment, without particular limitation.

[0092] According to some embodiments of the present invention, preferably, the temperature of the heat treatment is 400-750° C.; preferably, the time of the heat treatment is 2-12 h, preferably 5-12 h.

[0093] A seventh aspect of the present invention provides a sodium ion battery, comprising the solid electrolyte material as described in the first aspect or the positive electrode material as described in the fifth aspect.

[0094] The present invention will be described in detail below through examples.

[0095] In the following examples and comparative examples, unless otherwise specified, the raw materials used are commercially available products.

[0096] In the following examples and comparative examples:

[0097] The material phase and crystal structure analysis was performed using an X-ray automatic diffractometer produced by Japan's Rigaku Company;

[0098] The particle size distribution test was performed using the Malvern Mastersizer 2000 laser particle size analyzer. In the experiment, only the average particle size D of the material was characterized. 50 ;

[0099] The button battery was charged, discharged and cycled using CT-3008 from Newway Electronics Co., Ltd.

[0100] The SP-150 electrochemical workstation produced by Bio-logic Company of France was used to perform AC impedance and electrochemical window tests.

[0101] Preparation Example is used to illustrate the solid electrolyte material provided by the present invention and the method for preparing the solid electrolyte material

[0102] Preparation Example 1

[0103] (1) In the presence of a solvent, a Na source, a Zr source, a Si source, and a P source are mixed to obtain a mixture A; wherein:

[0104] The solvent is water; the Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4;

[0105] The ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65;

[0106] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0107] The solid content of mixture A at 25°C is 50wt%;

[0108] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0109] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0110] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0111] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0112] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0113] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 500° C. and a pre-sintering time of 2 hours;

[0114] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 48μm;

[0115] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 13μm; chemical formula is Na3Zr2Si2PO 12 ;in:

[0116] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1050°C and sintering time of 8 hours; the crushing was carried out in a jet mill;

[0117] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 148nm; among which:

[0118] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0119] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0120] The drying conditions are: temperature 60°C and time 12 h.

[0121] Preparation Example 2

[0122] (1) In the presence of a solvent, Na source, M 1 The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; and the M 1 The source is Y2O3;

[0123] The ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65;

[0124] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0125] The solid content of mixture A at 25°C is 50wt%;

[0126] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0127] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0128] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0129] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0130] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0131] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 450° C. and a pre-sintering time of 2 hours;

[0132] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 45μm;

[0133] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 14μm; chemical formula is Na 3.05 Zr 1.95 Y 0.05 Si2PO 12 ;in:

[0134] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1050°C and sintering time of 6 hours; the crushing was carried out in a jet mill;

[0135] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 is 128nm; among which:

[0136] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0137] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0138] The drying conditions are: temperature 60°C and time 12 h.

[0139] Preparation Example 3

[0140] (1) In the presence of a solvent, Na source, M 2 The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; and the M 2 The source is Sc2O3;

[0141] The molar amount of Na in the Na source and the molar amount of Si in the Si source and M 2 Source M 2 The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65;

[0142] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0143] The solid content of mixture A at 25°C is 50wt%;

[0144] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0145] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0146] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0147] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0148] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0149] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 400° C. and a pre-sintering time of 3 hours;

[0150] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 46μm;

[0151] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 14μm; chemical formula is Na 3.05 Zr2Si 1.95 Sc 0.05 PO 12 ;in:

[0152] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1150°C and sintering time of 7 hours; the crushing was carried out in a jet mill;

[0153] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 is 126nm; among which:

[0154] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0155] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0156] The drying conditions are: temperature 60°C and time 12 h.

[0157] Preparation Example 4

[0158] (1) In the presence of a solvent, Na source, M 1 Source, M 2 The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; and the M 1 The source is Y2O3; M 2 The source is Sc2O3;

[0159] The molar amount of Na in the Na source and the molar amount of Si in the Si source and M 2 Source M 2 The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65;

[0160] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0161] The solid content of mixture A at 25°C is 50wt%;

[0162] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0163] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0164] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0165] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0166] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0167] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 550° C. and a pre-sintering time of 2 hours;

[0168] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 42μm;

[0169] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 12μm; chemical formula is Na 3.1 Zr 1.95 Y 0.05 Si 1.95 Sc 0.05 PO 12 ;in:

[0170] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1100°C and sintering time of 8 hours; the crushing was carried out in a jet mill;

[0171] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 is 125nm; among which:

[0172] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0173] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0174] The drying conditions are: temperature 60°C and time 12 h.

[0175] Preparation Example 5

[0176] (1) In the presence of a solvent, Na source, M 1 Source, M 2 The source, Zr source, Si source and P source are mixed to obtain a mixture A; wherein:

[0177] The solvent is water; the Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; M 1 The source is Y2O3; M 2 The source is Ga2O3;

[0178] The molar amount of Na in the Na source and the molar amount of Si in the Si source and M 2 Source M 2 The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65;

[0179] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0180] The solid content of mixture A at 25°C is 50wt%;

[0181] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0182] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0183] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0184] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0185] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0186] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 500° C. and a pre-sintering time of 2 hours;

[0187] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 44μm;

[0188] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 12μm; chemical formula is Na 3.1 Zr 1.95 Y 0.05 Si 1.95 Ga 0.05 PO 12 ;in:

[0189] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1100°C and sintering time of 8 hours; the crushing was carried out in a jet mill;

[0190] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 is 137nm; among which:

[0191] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0192] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0193] The drying conditions are: temperature 60°C and time 12 h.

[0194] Preparation Example 6

[0195] (1) In the presence of a solvent, Na source, M 1 Source, M 2 The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; and the M 1The source is Y2O3; M 2 The source is GeO2;

[0196] The molar amount of Na in the Na source and the molar amount of Si in the Si source and M 2 Source M 2 The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65;

[0197] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0198] The solid content of mixture A at 25°C is 50wt%;

[0199] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0200] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0201] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0202] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0203] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0204] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 500° C. and a pre-sintering time of 2 hours;

[0205] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 44μm;

[0206] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 12μm; chemical formula is Na 3.05 Zr 1.95 Y 0.05 Si 1.95 Ge 0.05 PO 12 ;in:

[0207] The sintering was carried out in a muffle furnace under the following conditions: sintering temperature of 1100°C and sintering time of 8 hours; the crushing was carried out in a jet mill;

[0208] (5) In the presence of water, the micron-scale solid electrolyte material is subjected to nano-processing to obtain a nano-scale solid electrolyte material with an average particle size D 50 is 132nm; among which:

[0209] The nano-processing comprises: sand-milling the micron-sized solid electrolyte material with water in a sand mill to obtain a nano-sized slurry having a solid content of 50 wt% at 25° C.; then drying the nano-sized slurry and grinding the obtained dry product using a jet mill;

[0210] The sand grinding conditions were as follows: speed 1000 r / min, time 2 h;

[0211] The drying conditions are: temperature 60°C and time 12 h.

[0212] Preparation Example 7

[0213] According to the method of Preparation Example 1, except that step (5) is not included, the rest are the same to obtain a micron-sized solid electrolyte material.

[0214] Preparation Example 8

[0215] (1) In the presence of a solvent, Na source, M 1 The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4; and the M 1 The source is La2O3;

[0216] The ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65;

[0217] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0218] The solid content of mixture A at 25°C is 50wt%;

[0219] (2) heating a mixture B containing a mixture A, an organic monomer, an initiator, and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; wherein:

[0220] The organic monomer is acrylamide; the initiator is (NH4)2S2O8; the catalyst is N,N,N',N'-tetramethylethylenediamine (TEMED);

[0221] The mass ratio of mixture A to organic monomer is 1:0.55; the mass ratio of organic monomer, initiator and catalyst is 1:1:1;

[0222] Mixture B is obtained by adding organic monomers, initiators and catalysts into mixture A and performing stirring and dispersion treatment;

[0223] The polymerization reaction was carried out in a forced air oven under the following conditions: polymerization temperature of 100°C and polymerization time of 12 hours;

[0224] (3) Pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; wherein the pre-sintering is performed in a muffle furnace under the following conditions: a pre-sintering temperature of 450° C. and a pre-sintering time of 2 hours;

[0225] The crushing process is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor II 50 43μm;

[0226] (4) The solid electrolyte precursor II is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 10μm; chemical formula is Na 3.05 Zr 1.95 La 0.05 Si2PO 12 ;in:

[0227] The sintering is carried out in a muffle furnace under the following conditions: sintering temperature of 1050° C. and sintering time of 6 hours; the crushing is carried out in a jet mill.

[0228] Comparative Preparation Example 1

[0229] (1) Mixing a Na source, a Zr source, a Si source, and a P source to obtain a mixed material; wherein:

[0230] The Na source is Na2CO3; the Zr source is ZrO2; the Si source is SiO2; the P source is NH4H2PO4;

[0231] The ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65;

[0232] The mixing was carried out in a ball mill mixer under the following conditions: a speed of 900 rpm and a time of 6 h;

[0233] (2) pre-sintering and crushing the mixture in sequence to obtain a solid electrolyte precursor;

[0234] The pre-sintering is carried out in a muffle furnace, and the pre-sintering conditions are as follows: the pre-sintering temperature is 700°C, and the pre-sintering time is 2 hours; the crushing is carried out in a wall breaking machine; the average particle size D of the solid electrolyte precursor is 50 45μm;

[0235] (3) The solid electrolyte precursor is sintered and crushed in sequence to obtain a micron-sized solid electrolyte material with an average particle size D 50 15μm; chemical formula is Na3Zr2Si2PO 12 ;

[0236] The sintering is carried out in a muffle furnace under the following conditions: the sintering temperature is 1050° C. and the sintering time is 8 hours; and the crushing is carried out in a jet mill.

[0237] Test Example 1

[0238] (a) The solid electrolyte materials obtained in the preparation examples and the comparative preparation examples were mixed with a polymer and a sodium salt to obtain a mixture; wherein: the amount of the solid electrolyte material was 8 g; the amount of the polymer was polyethylene oxide (PEO) was 69 g; and the amount of the sodium salt was NaTFSI was 23 g;

[0239] The mixing conditions were as follows: mixing temperature was 85°C, rotation speed was 500 rpm, and mixing time was such that the torque of the mixer reached a steady state;

[0240] (b) placing the mixture on a flat-plate hot press heating table for hot pressing to obtain a solid electrolyte membrane having a thickness of 20 μm; wherein the hot pressing conditions are: hot pressing temperature of 70° C., hot pressing pressure of 3 MPa, and hot pressing time of 20 min.

[0241] The above-mentioned solid electrolyte membrane was punched into discs with a diameter of 22 mm. After vacuum drying at 60°C for 12 h, the positive electrode shell, stainless steel sheet I (diameter 18 mm, thickness 1 mm), solid electrolyte membrane, stainless steel sheet II (diameter 18 mm, thickness 1 mm), nickel foam and negative electrode shell were assembled in the order of H2O content <1 ppm and O2 content <1 ppm in a glove box. After sealing at 450 MPa pressure, the test assembly was obtained. The test assembly was heated at 65°C for 12 h for chemical activation, and then charged at 1.3 mA for 5 min, allowed to stand for 3 min, discharged at 1.3 mA for 5 min, and allowed to stand for 3 min. The above charging and discharging steps were cycled three times for electrochemical activation to obtain a sample for ionic conductivity testing.

[0242] The obtained ionic conductivity test sample was placed in an electrochemical workstation to test the AC impedance at room temperature. The test conditions were: disturbance voltage 5-10mV, scanning frequency range 1Hz-1MHz, and the impedance data obtained from the test were calculated according to the formula σ=L / (R·S) (where: σ is ionic conductivity, unit is S / cm; L is the thickness of the solid electrolyte membrane after the test component is disassembled, unit is cm; R is the impedance value, unit is Ω; S is the area of ​​the solid electrolyte membrane, unit is cm) 2 ) The corresponding ionic conductivity of the sample was calculated, and the results are shown in Table 1.

[0243] Test Example 2

[0244] 10g of each solid electrolyte material obtained in the preparation example and the comparative preparation example were placed in 90g of 100℃ boiling water and stirred for 2h; the stirred samples were evaporated and dried, and then XRD test was performed. The peak intensity of the (020) crystal plane obtained by XRD was I (020) The peak intensity I of (421) crystal plane (421) Ratio I (020) / I (421) , (020) crystal plane peak area A (020) The peak area A of (421) crystal plane (421) Ratio A (020) / A (421) , and the results of the structural stability test are shown in Table 1. The XRD spectra of the solid electrolyte materials obtained in the preparation example and the comparative preparation example are shown in Figure 1; the XRD spectra of the solid electrolyte materials obtained in the preparation example and the comparative preparation example after the abuse test are shown in Figure 2. Among them:

[0245] The main body of the sample of the solid electrolyte material obtained in Preparation Example 1 is a pure phase, with a small amount of sodium phosphate impurity phase appearing at the diffraction angle positions of 2θ=28° and 32°. After the abuse treatment, the sample has no impurity phase, indicating that the sample has good structural stability.

[0246] The solid electrolyte material obtained in Preparation Example 2 is a pure phase; after the abuse treatment, the sample is basically free of impurities, indicating that the sample structure is relatively stable;

[0247] The solid electrolyte materials obtained in Preparation Examples 3-6 are pure phases; the samples treated by the abuse method have no impurity phases, indicating that the sample structure is excellent in stability;

[0248] The main body of the sample of the micron-sized solid electrolyte material obtained in Preparation Example 7 is a pure phase, and a small amount of sodium phosphate impurity phase appears at the diffraction angle positions of 2θ = 26° and 28°. After the abuse treatment, the peak intensity of the sodium phosphate impurity phase at the diffraction angle positions of 2θ = 26° and 28° becomes stronger, and a large amount of zirconium oxide impurity phase appears at the diffraction angle position of 2θ = 32°, indicating that the sample has undergone phase transformation and poor structural stability.

[0249] The sample of the micron-sized solid electrolyte material obtained in Comparative Preparation Example 1 is mainly pure phase, and a small amount of sodium phosphate impurity phase appears at the diffraction angle positions of 2θ=26° and 28°. After the sample is treated by the abuse method, the peak intensity of the sodium phosphate impurity phase at the diffraction angle positions of 2θ=26° and 28° becomes stronger, and a large amount of zirconium oxide impurity phase appears at the diffraction angle position of 2θ=32°, indicating that the sample has undergone phase transformation and poor structural stability.

[0250] The main body of the sample of the micron-scale solid electrolyte material obtained in Preparation Example 8 is a pure phase; after the sample is treated in an abusive manner, a large amount of zirconium oxide impurity phase appears at the diffraction angle position of 2θ=32°, indicating that the sample has undergone phase transformation and poor structural stability.

[0251] Table 1

[0252] The examples are used to illustrate the positive electrode material and the method for preparing the positive electrode material provided by the present invention.

[0253] Example 1

[0254] S1: The nano-scale solid electrolyte material obtained in Preparation Example 1 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is an O3-type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0255] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.8:100;

[0256] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0257] The heat treatment conditions are as follows: temperature of 500°C and time of 6 hours.

[0258] Example 2

[0259] S1: The nano-scale solid electrolyte material obtained in Preparation Example 2 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is a P2-type layered oxide Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2;

[0260] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.5:100;

[0261] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0262] The heat treatment conditions are as follows: temperature of 750°C and time of 12h.

[0263] Example 3

[0264] S1: The nano-scale solid electrolyte material obtained in Preparation Example 3 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is an O3-type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0265] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.5:100;

[0266] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0267] The heat treatment conditions are as follows: temperature of 550°C and time of 6 hours.

[0268] Example 4

[0269] S1: The nano-scale solid electrolyte material obtained in Preparation Example 4 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is an O3-type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0270] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.6:100;

[0271] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0272] The heat treatment conditions are as follows: temperature of 450° C. and time of 10 h.

[0273] Example 5

[0274] S1: The nano-scale solid electrolyte material obtained in Preparation Example 5 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is a P2-type layered oxide Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2;

[0275] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.6:100;

[0276] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0277] The heat treatment conditions are as follows: temperature of 450° C. and time of 10 h.

[0278] Example 6

[0279] S1: The nano-scale solid electrolyte material obtained in Preparation Example 6 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is a P2-type layered oxide Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2;

[0280] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.6:100;

[0281] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0282] The heat treatment conditions are as follows: temperature of 450° C. and time of 10 h.

[0283] Example 7

[0284] S1: The nano-scale solid electrolyte material obtained in Preparation Example 7 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein the positive electrode active material is an O3-type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0285] The mass ratio of nano-scale solid electrolyte material to positive electrode active material is 0.8:100;

[0286] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the nano-scale solid electrolyte material is coated on the surface of the positive electrode active material;

[0287] The heat treatment conditions are as follows: temperature of 500°C and time of 6 hours.

[0288] Example 8

[0289] S1: The micron-sized solid electrolyte material obtained in Preparation Example 8 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein: the positive electrode active material is a P2-type layered oxide Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2;

[0290] The mass ratio of micron-sized solid electrolyte material to positive electrode active material is 0.5:100;

[0291] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which a micron-sized solid electrolyte material is coated on the surface of the positive electrode active material; wherein:

[0292] The heat treatment conditions are: temperature 750°C and time 12h.

[0293] Comparative Example 1

[0294] The positive electrode active material (O3 type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2) is heat-treated in an oxygen furnace to obtain a positive electrode material; wherein the heat treatment conditions are: temperature 850°C and time 8h.

[0295] Comparative Example 2

[0296] The positive electrode active material (P2 type layered oxide Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2) is heat-treated in an oxygen furnace to obtain a positive electrode material; wherein the heat treatment conditions are: temperature 900°C and time 6 hours.

[0297] Comparative Example 3

[0298] S1: The micron-sized solid electrolyte material obtained in Comparative Preparation Example 1 is mixed with the positive electrode active material in a high-speed mixer to obtain a mixture; wherein: the positive electrode active material is an O3-type layered oxide NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2;

[0299] The mass ratio of micron-sized solid electrolyte material to positive electrode active material is 0.8:100;

[0300] S2: heat-treating the obtained mixture in an oxygen furnace to obtain a positive electrode material, in which the micron-sized solid electrolyte material is coated on the surface of the positive electrode active material; wherein the heat treatment conditions are: temperature of 750° C. and time of 12 hours.

[0301] Test Example 3

[0302] 5 g of the positive electrode materials obtained in the examples and comparative examples were weighed and placed in 95 g of room temperature deionized water. 水 The slurry obtained after stirring was filtered through a Buchner funnel with filter paper to obtain a mass of M 滤液 The filtrate was titrated in a Metrohm 888 potentiometric titrator at room temperature to obtain a titration curve. The equivalent point EP in the titration curve was recorded. x =V x , (x=1,2,3···). The results are shown in Table 2.

[0303] Test Example 4

[0304] The positive electrode materials obtained in the examples and comparative examples were mixed with conductive carbon black, PVDF, and NaTFSI in a mass ratio of 90:3:5:2, and an appropriate amount of NMP was added. After stirring evenly, the mixture was spread on aluminum foil by knife-drawing, dried in a forced air oven at 120°C for 1 hour, and punched into positive electrode sheets with a diameter of 11 mm.

[0305] 69 g of PEO and 23 g of NaTFSI were dissolved in acetonitrile and stirred for 12 hours. The resulting slurry was then cast into a polytetrafluoroethylene mold and dried in a 50°C oven under vacuum for 10 hours. The resulting product was then hot-pressed in a press for 5 minutes and punched into a 19 mm diameter disc-shaped PEO electrolyte membrane.

[0306] The negative electrode (metallic lithium), the prepared positive electrode sheet, and the PEO electrolyte membrane were assembled into 2025-type button cells in an Ar glove box with water and oxygen contents less than 5 ppm. The cells were tested for charge and discharge capacity at 2.0-4.2 V, 0.1 C, and 60°C. Their charge and discharge performance was tested by charging and discharging 50 times at 2.0-4.2 V, 1 C, and 60°C. The results are shown in Table 2.

[0307] Test Example 5

[0308] The positive electrode materials obtained in the examples and comparative examples were mixed with acetylene black and polyvinylidene fluoride (PVDF) in a mass ratio of 95:2.5:2.5, respectively. An appropriate amount of NMP was added, stirred evenly, and then coated onto aluminum foil. The mixture was dried in a forced-air oven at 120°C for 1 hour and then stamped into a 12 mm diameter, 120 μm thick positive electrode sheet using a pressure of 100 MPa. The positive electrode sheet was then dried in a vacuum oven at 120°C for 12 hours. Carbon black was used for the negative electrode; a 25 μm thick polyethylene porous membrane was used as the separator; and an electrolyte solution consisting of an equal mixture of 1 mol / L NaPF6, ethylene carbonate (EC), and propylene carbonate (PC) was used as the electrolyte. The positive electrode sheet, separator, negative electrode sheet, and electrolyte were assembled into 2025-type button cells in an Ar glove box with a water and oxygen content of less than 5 ppm.

[0309] The button cell was charged and discharged twice at 2.0-4.2V, 0.2C, and 25°C. After being fully charged, the cell was disassembled to obtain a positive electrode sheet. This positive electrode sheet was then tested in a differential thermal-thermogravimetric tester to obtain the corresponding DSC curve. The results are shown in Table 2.

[0310] Table 2

[0311] The above results demonstrate that the solid electrolyte material provided by the present invention has high ionic conductivity and a stable structure. However, the presence of a zirconium oxide impurity phase in the micron-sized solid electrolyte material obtained in Comparative Preparation Example 1 affects grain boundary impedance and poor structural stability. Once coated on the surface of the positive electrode active material, the impurity phase hinders sodium ion transport, affecting the electrochemical performance of the resulting positive electrode material.

[0312] Although La-doped elements are introduced into the micron-scale solid electrolyte material obtained in Preparation Example 8, since the elements and the main phase are not evenly mixed at the atomic level, zirconium oxide impurities appear after abuse treatment, which affects the grain boundary impedance and has poor structural stability. After it is coated on the surface of the positive electrode active material, the presence of the impurity phase will hinder the transmission of sodium ions and affect the electrochemical properties of the positive electrode material.

[0313] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A solid electrolyte material, characterized in that: The peak intensity I of the (020) crystal plane of the solid electrolyte material obtained by XRD (020) The peak intensity I (421) The ratio satisfies 0.9≤I (020) / I (421) <1; The peak area A of the (020) crystal plane of the solid electrolyte material obtained by XRD (020) The peak area A of (421) crystal plane (421) The ratio satisfies 0.45≤A (020) / A (421) <1.

2. The solid electrolyte material according to claim 1, wherein 0.97≤I (020) / I (421) <1; Preferably, 0.46≤A (020) / A (421) <1.

3. The solid electrolyte material according to claim 1 or 2, wherein: The solid electrolyte material has a structure shown in Formula I: Na 3+x [Zr 2-y M 1 y ][Si 2-z M 2 z ]PO 12 Formula I; Among them, 0≤x<1.15, 0≤y≤0.5, 0≤z≤1; M 1 is at least one of Mg, La, Y, Al, and Ca; M 2 It is at least one of Ga, In, Ge and Sc.

4. The solid electrolyte material according to any one of claims 1 to 3, wherein: The average particle size D of the solid electrolyte material 50 5-500nm, preferably 100-200nm; Preferably, the ionic conductivity of the solid electrolyte material is greater than 8×10 -5 S / cm, preferably greater than 1×10 -4 S / cm.

5. A method for preparing a solid electrolyte material as claimed in any one of claims 1 to 4, characterized in that: The method comprises the following steps: (1) In the presence of a solvent, a Na source, a Zr source, a Si source and a P source are mixed to obtain a mixture A; optionally, the mixture A further contains M 1 Source and / or M 2 source; (2) heating a mixture B containing the mixture A, an organic monomer, an initiator and a catalyst to perform a polymerization reaction to obtain a solid electrolyte precursor I; (3) pre-sintering and crushing the solid electrolyte precursor I in sequence to obtain a solid electrolyte precursor II; (4) The solid electrolyte precursor II is sintered and crushed in sequence.

6. The method according to claim 5, wherein: In step (1), the solvent is selected from at least one of water, N-methyl-2-pyrrolidone, phthalate, dibasic lipid, long-chain alcohol and pyrrolidone; Preferably, in step (1), the M 1 Source and the M 2 The sources are each independently selected from 1 and / or M 2 At least one of oxides, hydroxides, nitrates, oxalates, organic alcohol salts and carbonates; Preferably, in step (1), the ratio of the molar amount of Na in the Na source to the molar amount of Si in the Si source, n(Na) / n(Si), is 1.65-1.725; when the mixed material A further contains M 2 When the Na source is used, the molar amount of Na in the Na source is equal to the molar amount of Si in the Si source and the molar amount of M 2 Source M 2 The ratio of the sum of the molar amounts of n(Na) / [n(Si)+n(M 2 )] is 1.65-1.725; Preferably, in step (1), the solid content of the mixture A at 25° C. is 40-60 wt %.

7. The method according to claim 5 or 6, wherein: In step (2), the organic monomer is selected from at least one of acrylamide, methylenebisacrylamide, styrene, butadiene and methyl methacrylate; Preferably, in step (2), the initiator is selected from at least one of benzoyl peroxide, (NH4)2S2O8 and K2S2O8; Preferably, in step (2), the catalyst is N,N,N',N'-tetramethylethylenediamine; Preferably, in step (2), the mass ratio of the mixture A to the organic monomer is 1:0.5-0.6; Preferably, in step (2), the mass ratio of the organic monomer, the initiator and the catalyst is 1:0.5-1.5:0.5-1.5; Preferably, in step (2), the polymerization reaction conditions include: polymerization temperature of 80-200° C., and polymerization time of 10-15 h.

8. The method according to any one of claims 5 to 7, wherein: In step (3), the pre-sintering conditions include: a pre-sintering temperature of 300-700° C. and a pre-sintering time of 2-6 hours; Preferably, in step (3), the average particle size D of the solid electrolyte precursor II is 50 1-50 μm, preferably 40-50 μm; Preferably, in step (4), the sintering conditions include: a sintering temperature of 1000-1200° C. and a sintering time of 4-10 h; Preferably, the method further comprises: in the presence of water, subjecting the product obtained by the crushing treatment in step (4) to nano-treatment to obtain a nano-scale solid electrolyte material.

9. A solid electrolyte, characterized in that The solid electrolyte comprises the solid electrolyte material according to any one of claims 1 to 4, a polymer and a sodium salt.

10. The solid electrolyte according to claim 9, wherein The polymer is selected from at least one of polyvinylidene fluoride, polytetrafluoroethylene, vinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, polydimethylsiloxane, polymethyl methacrylate, polypropylene carbonate, polyethylene carbonate and polycaprolactone; Preferably, the sodium salt is selected from at least one of NaTFSI, sodium hexafluorophosphate, sodium perchlorate and sodium trifluoromethanesulfonate; Preferably, based on the total mass of the solid electrolyte, the content of the solid electrolyte material is 5-30wt%, the content of the polymer is 50-75wt%, and the content of the sodium salt is 15-30wt%; Preferably, the solid electrolyte is a membrane structure, and the thickness of the membrane structure is 5-200 μm, preferably 20-100 μm.

11. A method for preparing the solid electrolyte according to claim 9 or 10, characterized in that: The method comprises: (a) mixing a solid electrolyte material, a polymer and a sodium salt to obtain a mixture; (b) subjecting the mixture to hot pressing.

12. The method according to claim 11, wherein: The mixing conditions in step (a) include: mixing temperature of 0.5-1.5T m , where T m is the softening temperature of the polymer; the rotation speed is 300-500rpm; Preferably, the conditions of the hot pressing treatment in step (b) include: hot pressing temperature of 60-80°C, hot pressing pressure of 1-10 MPa, and hot pressing time of 5-20 min.

13. A positive electrode material, characterized in that: The positive electrode material comprises a positive electrode active material and a solid electrolyte material coated on the surface of the positive electrode active material, and the solid electrolyte material is the solid electrolyte material according to any one of claims 1 to 4.

14. The positive electrode material according to claim 13, wherein The mass ratio of the solid electrolyte material to the positive electrode active material is 0.05-1:100, preferably 0.5-0.8:100; Preferably, the positive electrode active material is NaNi 1 / 3 Fe 1 / 3 Mn 1 / 3 O2、Na 2 / 3 Ni 1 / 3 Mn 1 / 2 O2 and at least one of the layered oxide positive electrode materials derived therefrom.

15. The positive electrode material according to claim 13 or 14, wherein The positive electrode material is subjected to acid-base titration treatment and a characteristic titration peak is present between pH=5-8; Preferably, in the differential scanning calorimetry analysis spectrum of the positive electrode material, the starting temperature of the main exothermic peak is above 290°C.

16. A method for preparing the positive electrode material according to any one of claims 13 to 15, characterized in that: The method comprises: The mixture containing the solid electrolyte material and the positive electrode active material is heat-treated at 300-750° C.; wherein the solid electrolyte material is the solid electrolyte material according to any one of claims 1-4.

17. The method according to claim 16, wherein: The temperature of the heat treatment is 400-750° C.; the time of the heat treatment is 2-12 hours, preferably 5-12 hours.

18. A sodium ion battery, characterized in that: The sodium ion battery comprises the solid electrolyte material as described in any one of claims 1 to 4 or the positive electrode material as described in any one of claims 13 to 15.

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