Solid-state electrolyte material and preparation method therefor, positive electrode active material, positive electrode sheet, solid-state battery and electric device

Abstract

Disclosed in the present application are a solid-state electrolyte material and a preparation method therefor, a positive electrode active material, a positive electrode sheet, a solid-state battery and an electric device. The solid-state electrolyte material is of a NASICON crystal structure. In an X-ray diffraction pattern of the solid-state electrolyte material, characteristic diffraction peaks appear at positions where the values of the diffraction angle 2θ are 14.5-14.8º, 19.5-19.7º, and 22.5-22.8º, respectively, wherein the ratio of the peak intensity I1 of the characteristic diffraction peak at the position where the value of the diffraction angle 2θ is 14.5-14.8º to the peak intensity I2 of the characteristic diffraction peak at the position where the value of the diffraction angle 2θ is 22.5-22.8° satisfies: 1.5≤I2 / I1≤3. Therefore, the ionic conductivity and structural stability of the solid electrolyte are improved.

Description

Solid electrolyte material and preparation method thereof, positive electrode active material, positive electrode sheet, solid-state battery and electrical equipment Technical Field

[0001] The present application relates to the field of batteries, and in particular to solid electrolyte materials and preparation methods thereof, positive electrode active materials, positive electrode sheets, solid-state batteries, and electrical equipment. Background Art

[0002] Range anxiety and battery safety issues have become the pain points and major bottlenecks that restrict the development of new energy vehicles. The key to iterative innovation of the next generation of higher energy density and safer power batteries lies in technological breakthroughs in solid-state batteries. As the core material of solid-state batteries, the comprehensive performance and industrialization progress of solid-state electrolytes are key to the development of solid-state batteries. Currently, solid-state electrolytes with industrialization prospects mainly include three major systems: polymers, sulfides, and oxides. Among them, although sulfide electrolytes have high conductivity, they have high manufacturing costs and face huge challenges in large-scale production and installation; polymer solid electrolytes are easy to process, but the battery is prone to short circuits; the ionic conductivity of oxide solid electrolytes is between that of polymers and sulfides, and the preparation difficulty is moderate, making it easy to achieve iterations from semi-solid, quasi-solid, to all-solid-state batteries. However, the oxide solid electrolytes in related technologies have the problem of not being able to take into account both the improvement of ionic conductivity and the stability of the powder structure, which affects the battery's rate performance and cycle performance. Summary of the Invention

[0003] The present application aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] The first aspect of the present application provides a solid electrolyte material, the solid electrolyte material having a NASICON crystal structure, and an X-ray diffraction spectrum of the solid electrolyte material having characteristic diffraction peaks at diffraction angles 2θ of 14.5°-14.8°, 19.5°-19.7°, and 22.5°-22.8°, respectively, wherein the ratio of the peak intensity I1 of the characteristic diffraction peak at 2θ values ​​of 14.5°-14.8° to the peak intensity I2 of the characteristic diffraction peak at 2θ values ​​of 22.5°-22.8° satisfies: 1.5≤I2 / I1≤3. Thus, a composite crystal structure having both hexagonal and monoclinic crystal systems is formed. At the same time, the solid electrolyte material contains both phosphate and pyrophosphate as the skeleton of the solid electrolyte material, which can improve the structural stability of the solid electrolyte material, reduce the confinement of carriers, and improve the mobility of carriers, thereby improving the ionic conductivity of the solid electrolyte material and improving the rate performance of the battery.

[0005] According to some embodiments of the present application, the X-ray diffraction spectrum of the solid electrolyte material has a characteristic diffraction peak I3 at 2θ of 17.8°-18.0° and / or 23.7°-23.9° and / or 26.8°-27.0°. Thus, the solid electrolyte material contains phosphate, pyrophosphate and heteropoly acid as the skeleton of the solid electrolyte material, which can further improve the structural stability of the solid electrolyte material, reduce the confinement of carriers, and improve the mobility of carriers, thereby improving the ionic conductivity of the solid electrolyte and improving the rate performance of the battery.

[0006] According to some embodiments of the present application, the X-ray diffraction spectrum of the solid electrolyte material shows a crystal plane along <113> The preferred orientation is such that the ratio of the peak intensities of the diffraction peak (113) and the diffraction peak (104) satisfies I(113) / I(104)≥2, preferably 2≤I(113) / I(104)≤4; the 2θ value corresponding to the diffraction peak (113) in the X-ray diffraction spectrum is 24.3°-24.6°, and the half-peak width range is 0.170-0.172, and the 2θ value corresponding to the diffraction peak (104) is 20.7°-20.9°, and the half-peak width range is 0.180-0.184. Thus, the content of the preferred crystal plane (113) in the solid electrolyte material is increased, the carrier transmission channel is widened, the carrier transmission rate is increased, and the ionic conductivity of the solid electrolyte material is thereby improved.

[0007] According to some embodiments of the present application, the solid electrolyte material has a charge and discharge platform at 2.4V-2.6V.

[0008] According to some embodiments of the present application, the solid electrolyte material includes: Li x M 1 y M 2 z M 3 u (PO4) w1 (P2O7) w2 (RO v ) w3 , where M 1 Including at least one of Mg, Na, K, optionally, M 1 including at least one of Mg or K; M 2 Including at least one of Al, Ga, In, Y, Sc, optionally, M 2 including at least one of Al or Y; M 3The solid electrolyte material comprises at least one of Ti, Zr, and Ge; R comprises at least one of Mo, W, Si, Cl, Br, S, Sb, Sn, F, and P, and optionally, R comprises at least one of Si, Mo, or W; 0 < x ≤ 5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 1, 0 ≤ u ≤ 9, 0 ≤ v ≤ 4, 1 ≤ w1 ≤ 3, 0 < w2 ≤ 2.3, 0 < w3 ≤ 3, and w1 + w2 + w3 = 3. Thus, the solid electrolyte material simultaneously has phosphate, pyrophosphate, and heteropolyacid as a skeleton, which can improve the structural stability of the solid electrolyte material, reduce the confinement of carriers, and improve the mobility of carriers, thereby improving the ionic conductivity of the solid electrolyte and the rate performance of the battery.

[0009] According to some embodiments of the present application, the solid electrolyte material satisfies at least one of the following conditions:

[0010] The ionic conductivity of the solid electrolyte material is greater than or equal to 1×10 -3 S / cm, which can be greater than or equal to 2×10 -3 S / cm;

[0011] The average particle size of the solid electrolyte material is 0.5 μm-20 μm, and can be optionally 0.5 μm-0.9 μm;

[0012] At 25°C, the pH of the solid electrolyte material is 6-10;

[0013] The surface of the solid electrolyte material includes residual lithium, and the residual lithium includes at least one of dilithium hydrogen phosphate, lithium dihydrogen phosphate, lithium carbonate, and lithium pyrophosphate. Based on the total mass of the solid electrolyte material, the mass proportion of the dilithium hydrogen phosphate is a, the mass proportion of the lithium dihydrogen phosphate is b, the mass proportion of the lithium carbonate is c, and the mass proportion of the lithium pyrophosphate is d, and the following conditions are satisfied: 0≤a≤0.5%, 0≤b≤0.1%, 0≤c≤0.3%, and 0≤d≤0.2%.

[0014] The second aspect of the present application provides a method for preparing the solid electrolyte material provided in the first aspect of the present application, comprising: 2 Source, M 3 Source, PO4 3- The first precursor is obtained by mixing the R source, the precipitant, and the solvent, and then co-precipitating and filtering to obtain the first precursor; the first precursor is mixed with the R source, and the first sintering is performed in an oxygen-containing atmosphere to obtain the second precursor; the second precursor is mixed with the Li source, the M 1 Source, P2O7 4-The solid electrolyte material is prepared by mixing the solid electrolyte material with the solid electrolyte material and performing a second sintering in an oxygen-free atmosphere. The solid electrolyte material prepared by this method thus possesses all the characteristics and advantages of the aforementioned solid electrolyte materials, which will not be elaborated here. In general, it has at least the advantages of high ionic conductivity and good structural stability.

[0015] According to some embodiments of the present application, the method further includes: 2 Source, the M 3 Source, the PO4 3- The source, the surfactant, the precipitant and the solvent are mixed, and the first precursor is obtained after co-precipitation and filtration; optionally, based on the PO4 3- The surfactant accounts for ≥0.1% of the total mass of the source, optionally ranging from 0.1% to 1%, and further optionally ranging from 0.3% to 0.7%. Optionally, the surfactant comprises at least one of polyvinyl pyrrolidone, sodium dodecylbenzenesulfonate, and a sulfonate. This reduces the formation energy of the first precursor along the preferred crystal plane, increases the proportion of the preferred crystal plane, increases the diffusion rate of lithium ions, and improves the ionic conductivity of the solid electrolyte material.

[0016] According to some embodiments of the present application, the method satisfies at least one of the following conditions:

[0017] The oxygen-containing atmosphere includes oxygen or air; the temperature of the first sintering is 700° C.-900° C., and the time of the first sintering is 4 h-10 h;

[0018] The oxygen-free atmosphere includes an inert gas or nitrogen; the temperature of the second sintering is 450° C.-700° C., and the time of the second sintering is 8 hours-20 hours;

[0019] The M 1 Sources include M 1 At least one of oxides, phosphates, sulfates, chlorides, nitrates, and carbonates;

[0020] The M 2 Sources include M 2 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate;

[0021] The M 3 Sources include M 3 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate;

[0022] The PO4 3-The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4;

[0023] The Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate;

[0024] The P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7;

[0025] The R source includes at least one of a simple substance, an oxide, and a hydride containing R; and the precipitant includes at least one of sodium hydroxide, sodium carbonate, and ammonia water.

[0026] The third aspect of the present application provides a positive electrode active material, comprising the solid electrolyte material provided in the first aspect of the present application or the solid electrolyte material prepared by the method provided in the second aspect of the present application; optionally, the positive electrode active material includes a matrix, at least part of the surface of the matrix has a coating layer, and the coating layer includes the solid electrolyte material; optionally, based on the total mass of the matrix, the mass proportion of the solid electrolyte material is 0.05%-1%.

[0027] The fourth aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided by the third aspect of the present application.

[0028] The fifth aspect of the present application provides a solid-state battery, comprising the positive electrode sheet provided in the fourth aspect of the present application.

[0029] The sixth aspect of the present application provides an electrical device, including the solid-state battery provided in the fifth aspect of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The above and / or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0031] FIG1 shows a schematic diagram of a process for preparing a solid electrolyte material according to an embodiment of the present application.

[0032] FIG2 shows the XRD test spectrum of the solid electrolyte material prepared in Example 3.

[0033] FIG3 shows the XRD test spectrum of the solid electrolyte material prepared in Example 5.

[0034] FIG4 shows the XRD test spectrum of the solid electrolyte material prepared in Comparative Example 1.

[0035] FIG5 shows the XRD test spectrum of the solid electrolyte material prepared in Example 2.

[0036] FIG6 shows the discharge curve of the solid electrolyte material prepared in Example 2. DETAILED DESCRIPTION

[0037] The embodiments of the present application are described in detail below. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this area or according to the product specifications. Reagents or instruments used that do not specify the manufacturer are conventional products that can be obtained commercially.

[0038] In a first aspect, the present application provides a solid electrolyte material having a NASICON crystal structure. In an X-ray diffraction spectrum of the solid electrolyte material, characteristic diffraction peaks are respectively present at diffraction angles 2θ of 14.5°-14.8°, 19.5°-19.7°, and 22.5°-22.8°, wherein the ratio of the peak intensity I1 of the characteristic diffraction peak at 2θ of 14.5°-14.8° to the peak intensity I2 of the characteristic diffraction peak at 2θ of 22.5°-22.8° satisfies the following conditions: 1.5≤I2 / I1≤3. Thus, the structural stability and ionic conductivity of the solid electrolyte material are simultaneously improved, thereby improving the rate performance of the battery.

[0039] The following is a detailed description of the principle by which this application can achieve the above beneficial effects:

[0040] The solid electrolyte material proposed in this application has a characteristic diffraction peak of phosphate at a 2θ value of 14.5°-14.8° in the X-ray diffraction spectrum, and a characteristic diffraction peak of pyrophosphate at a 2θ value of 22.5°-22.8°, indicating that the solid electrolyte material contains both pyrophosphate and phosphate as a skeleton. Specifically, the bond energy between phosphate and metal elements is relatively strong, and the probability of phase transition of the crystal structure can be reduced during the transmission of metal ions (taking lithium ions as an example), thereby improving the structural stability of the solid electrolyte material and reducing the precipitation of lithium ions at positions such as the bulk, grain boundaries, and surface of the solid electrolyte material. The bond energy between pyrophosphate and metal elements is lower than that between phosphate and metal elements. The presence of pyrophosphate can weaken the bond to lithium ions, improve the mobility of lithium ions, and thereby improve the migration rate of lithium ions, thereby improving the ionic conductivity of the solid electrolyte material and the rate performance of the battery. At the same time, the present application optimizes the content of phosphate and pyrophosphate in the solid electrolyte material by making the ratio of I2 / I1 within the above range to further improve the structural stability and ionic conductivity of the solid electrolyte material. On this basis, the characteristic diffraction peak at a 2θ value of 19.5°-19.7° indicates that the solid electrolyte material has both hexagonal and monoclinic crystal systems. The presence of the monoclinic crystal structure makes the unit cell parameters of the solid electrolyte material relatively large, and the anion binding during lithium ion transmission is weakened, which can further improve the ionic conductivity of the solid electrolyte material.

[0041] In this application, the X-ray diffraction test method is to use an X-ray automatic diffractometer for phase and crystal structure analysis, with an operating voltage of 40kV, an operating current of 250mA, continuous scanning, a scanning speed of 4° / min, a step size of 0.02°, and a scanning angle of 10°-80°.

[0042] As an example, I2 / I1 may be 1.5, 2, 2.5, or 3, etc., or may be a range consisting of any of the above values.

[0043] According to some embodiments of the present application, the X-ray diffraction spectrum of the solid electrolyte material has a characteristic diffraction peak I3 at a 2θ value of 17.8°-18.0° and / or 23.7°-23.9° and / or 26.8°-27.0°. For example, when the solid electrolyte material contains molybdate, it has a characteristic diffraction peak at a 2θ value of 17.8°-18.0°; when the solid electrolyte material contains tungstate, it has a characteristic diffraction peak at a 2θ value of 23.7°-23.9°; when the solid electrolyte material contains silicate, it has a characteristic diffraction peak at a 2θ value of 26.8°-27.0°. That is to say, heteropolyacids are doped at the phosphate position, coordinating with pyrophosphate and phosphate skeleton structures. When phosphate, pyrophosphate and heteropolyacids are contained at the same time, the stability of the skeleton and the widening of ion channels can be better balanced. Specifically, based on the weak bond energy between pyrophosphate and heteropolyacids and metal elements, compared with phosphate, the binding of lithium ions can be further weakened, the mobility of lithium ions can be improved, and the migration rate of lithium ions can be increased, the ionic conductivity of solid electrolyte materials can be increased, and the rate performance of batteries can be improved. Compared with phosphate doped with pyrophosphate, it can have better skeleton stability, reduce the probability of phase change of crystal structure during lithium ion transmission, and improve the cycle performance of batteries.

[0044] According to some embodiments of the present application, the X-ray diffraction spectrum of the solid electrolyte material shows a crystal plane along <113> Preferred orientation, the ratio of the peak intensity of the diffraction peak (113) to the diffraction peak (104) satisfies I(113) / I(104)≥2; the 2θ value corresponding to the diffraction peak (113) of the X-ray diffraction spectrum is 24.3°-24.6°, and the half-peak width range is 0.170-0.172, and the 2θ value corresponding to the diffraction peak (104) is 20.7°-20.9°, and the half-peak width range is 0.180-0.184. Therefore, by making I(113) / I(104)≥2, the content of the 113 crystal plane can be increased, thereby increasing the transmission channel of lithium ions, increasing the transmission rate of lithium ions, and thus improving the ionic conductivity of the solid electrolyte. When the half-peak widths of the diffraction peaks corresponding to the diffraction peaks (113) and the diffraction peaks (104) are within the above range, the electrolyte has better crystallization performance, thereby obtaining better structural stability.

[0045] As an example, I(113) / I(104) can be 2, 2.5, 3, 3.5, 4, 4.5 or 5, or can be a range consisting of any of the above values. According to some embodiments of the present application, 2≤I(113) / I(104)≤4.

[0046] According to some embodiments of the present application, the solid electrolyte material has a charge and discharge platform at 2.4V-2.6V.

[0047] According to some embodiments of the present application, the solid electrolyte material may include Li x M 1 y M 2 z M 3 u (PO4) w1 (P2O7) w2 (RO v ) w3 , where M 1 including at least one of Mg, Na, and K; M 2 Including at least one of Al, Ga, In, Y, and Sc; M 3 The solid electrolyte material comprises at least one of Ti, Zr, and Ge; R comprises at least one of Mo, W, Si, Cl, Br, S, Sb, Sn, F, and P; 0 < x ≤ 5, 0 ≤ y ≤ 0.5, 0 ≤ z ≤ 1, 0 ≤ u ≤ 9, 0 ≤ v ≤ 4, 1 ≤ w1 ≤ 3, 0 < w2 ≤ 3, 0 < w3 ≤ 3, and w1 + w2 + w3 = 3. Thus, the solid electrolyte material simultaneously uses phosphate, pyrophosphate, and heteropolyacid as the skeleton of the solid electrolyte material. The bond energy between the phosphate and the metal element is relatively strong, which can reduce the probability of phase transition of the crystal structure during lithium ion transmission, improve the structural stability of the solid electrolyte material, and reduce the precipitation of lithium in the bulk, grain boundaries, and surface of the solid electrolyte material. At the same time, pyrophosphate and heteropoly acid are used to replace part of the phosphate as the skeleton. Since the bond energy between pyrophosphate and heteropoly acid and metal elements is lower than the bond energy between phosphate and metal elements, the binding of lithium ions can be weakened, the mobility of lithium ions can be improved, and the migration rate of lithium ions can be increased, thereby improving the ionic conductivity of the solid electrolyte material. The solid electrolyte material has both hexagonal and monoclinic crystal systems. The presence of the monoclinic crystal structure makes the unit cell parameters of the solid electrolyte material relatively large, and the anion binding during the lithium ion transmission process is weakened, thereby improving the ionic conductivity of the solid electrolyte material. In addition, the present application has a transition metal position (M 3 ) doped M 2 , lithium doping M 1 Afterwards, based on M 2 Compared to M 3 The change of valence, and M 1 Compared with the change in the valence of lithium ions, in order to maintain electrical neutrality, the Li content in the unit cell of the solid electrolyte material increases, which can increase the transmission channel of lithium ions, increase the transmission rate of lithium ions, further improve the ionic conductivity of the solid electrolyte material, and improve the rate performance of the battery.

[0048] As an example, 0<x≤5, for example, can be 0.5, 1, 2, 3, 4 or 5, or can be a composition range of any of the above values. In this way, the content of lithium in the solid electrolyte material is increased, the number of lithium ions is increased, and the transmission channels of lithium ions are increased, the transmission rate of lithium ions is increased, and the ionic conductivity of the solid electrolyte material is increased. According to some specific embodiments of the present application, 1≤x≤4.

[0049] As an example, 0≤y≤0.5, for example, can be 0, 0.1, 0.2, 0.3, 0.4 or 0.5, or can be a range consisting of any of the above values. Thus, the ionic conductivity of the solid electrolyte material is improved. According to some specific embodiments of the present application, 0<y≤0.01.

[0050] As an example, 0≤z≤1, for example, can be 0, 0.2, 0.4, 0.6, 0.8 or 1, or can be a range consisting of any of the above values. 3 ) doped M 2 Afterwards, based on M 2 Compared to M 3 To maintain electrical neutrality, the Li content in the solid electrolyte material unit cell increases, thereby increasing the lithium ion transmission channel, improving the lithium ion transmission rate, further improving the ionic conductivity of the solid electrolyte material, and improving the rate performance of the battery. According to some specific embodiments of the present application, 0.1≤z≤0.8.

[0051] As an example, 0≤u≤9, for example, it can be 0, 1, 2, 3, 4, 5, 6, 7, 8 or 9, or can be a range consisting of any of the above values. 3 It can be used as an element constituting the skeleton structure of solid electrolyte materials, by cooperating with the heterovalent element M 1 、M 2 Doping can increase the carrier concentration, increase the carrier transport sites, improve the carrier mobility, and thus improve the intrinsic ionic conductivity of the solid electrolyte material. According to some specific embodiments of the present application, 1≤u≤3.

[0052] As an example, 0≤v≤4, for example, it can be 0, 1, 2, 3 or 4, or can be a range consisting of any of the above values. According to some specific embodiments of the present application, 0<v<4.

[0053] As an example, 1≤w1≤3, for example, can be 1, 1.5, 2, 2.5 or 3, or can be a range consisting of any of the above values. Therefore, phosphate serves as the skeleton of the solid electrolyte material. Due to the strong bond energy between phosphate and metal elements, it can enhance the binding of metal elements, reduce the probability of phase transition of the crystal structure during lithium ion transmission, improve the structural stability of the solid electrolyte material, and maintain low lithium precipitation in the solid electrolyte material at locations such as the bulk, grain boundaries, and surface.

[0054] As an example, 0<w2≤2.3, for example, it can be 0.5, 1, 1.5, 2 or 2.3, or it can be a range composed of any of the above values. Therefore, pyrophosphate is used to replace part of the phosphate as the skeleton of the solid electrolyte material. Since the bond energy between the pyrophosphate and the metal element is weaker than the bond energy between the phosphate and the metal element, it can reduce the binding of the carriers, reduce the carrier transmission barrier, increase the carrier transmission rate, and thus improve the ionic conductivity of the solid electrolyte material. At the same time, by doping M in the solid electrolyte material 2 and M 3 , which can improve the structural stability of the solid electrolyte material and reduce the probability of phase transition of the solid electrolyte material. According to some specific embodiments of the present application, 0.1<w2≤1.

[0055] As an example, 0<w3≤3, for example, it can be 0.5, 1, 1.5, 2, 2.5 or 3, or it can be a range composed of any of the above values. Therefore, by using heteropoly acid to replace part of the phosphate as the skeleton of the solid electrolyte material, since the bond energy between the heteropoly acid and the metal element is weaker than the bond energy between the phosphate and the metal element, it can reduce the binding of the carriers, reduce the carrier transmission barrier, increase the carrier transmission rate, and thus improve the ionic conductivity of the solid electrolyte material. At the same time, by doping M in the solid electrolyte material 2 and M 3 , which can improve the structural stability of the solid electrolyte material and reduce the probability of phase transition of the solid electrolyte material. According to some specific embodiments of the present application, 0<w3≤1.5.

[0056] As an example, M 1 At least one of Mg or K may be included.

[0057] As an example, M 2 At least one of Al or Y may be included.

[0058] As an example, R may include at least one of Si, Mo, or W.

[0059] According to some embodiments of the present application, the ionic conductivity of the solid electrolyte material is greater than or equal to 1×10-3 S / cm, for example, can be 1×10 -3 S / cm, 2×10 -3 S / cm, 2.5×10 -3 S / cm or 3×10 -3 S / cm, etc., or can be a range composed of any of the above values. Thus, the transfer rate of lithium ions by the solid electrolyte material is improved, and the rate performance of the battery is improved. According to some specific embodiments of the present application, the ionic conductivity of the solid electrolyte material is greater than or equal to 2×10 -3 S / cm.

[0060] In this application, the test method for ionic conductivity is to form 5 mg of solid electrolyte material into a sheet sample at a pressure of 200 MPa in a steel mold with a diameter of 12 mm, and then place the formed sheet sample in a fixture and perform AC impedance testing on an electrochemical workstation to obtain ionic conductivity.

[0061] According to some embodiments of the present application, the average particle size of the solid electrolyte material may be 0.5 μm-20 μm, for example, 0.5 μm, 1 μm, 5 μm, 10 μm, 15 μm or 20 μm, or a range consisting of any of the above values. Thus, the solid electrolyte material can take into account both good dispersibility and high ionic conductivity. According to some specific embodiments of the present application, the average particle size of the solid electrolyte material may be 0.5 μm-0.9 μm.

[0062] In the present application, the average particle size of the solid electrolyte material is tested by dispersing the solid electrolyte material in a water solvent using a laser particle size analyzer to test its particle size distribution.

[0063] According to some embodiments of the present application, at 25°C, the pH of the solid electrolyte material is 6-10. For example, it can be 6, 7, 8, 9, or 10, or can be a range consisting of any of the above values. Thus, by keeping the pH within the above range, the structural stability of the solid electrolyte material is improved, and the impact of structural instability on ionic conductivity is reduced. At the same time, sufficient lithium is contained in the solid electrolyte material to improve the purity and ionic conductivity of the solid electrolyte material.

[0064] According to some embodiments of the present application, the surface of the solid electrolyte material includes residual lithium, and the residual lithium includes at least one of dilithium hydrogen phosphate, lithium dihydrogen phosphate, lithium carbonate, and lithium pyrophosphate. Based on the total mass of the solid electrolyte material, the mass proportion of the dilithium hydrogen phosphate is a, the mass proportion of the lithium dihydrogen phosphate is b, the mass proportion of the lithium carbonate is c, and the mass proportion of the lithium pyrophosphate is d, and the following conditions are satisfied: 0≤a≤0.5%, 0≤b≤0.1%, 0≤c≤0.3%, and 0≤d≤0.2%. Therefore, by testing the type of residual lithium, it can be inferred that the composition of the product must contain pyrophosphate, and the content of residual lithium is within the above range, reducing the probability of lithium inside the solid electrolyte material continuously precipitating to the surface and improving the structural stability of the solid electrolyte material.

[0065] As an example, 0≤a≤0.5%, for example, it can be 0, 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc., or can be a range consisting of any of the above values.

[0066] As an example, 0≤b≤0.1%, for example, it can be 0, 0.02%, 0.04%, 0.06%, 0.08% or 0.1%, etc., or can be a range consisting of any of the above values.

[0067] As an example, 0≤c≤0.3%, for example, it can be 0, 0.05%, 0.1%, 0.15%, 0.2%, 0.25% or 0.3%, etc., or it can be a range consisting of any of the above values.

[0068] As an example, 0≤d≤0.2%, for example, it can be 0, 0.05%, 0.1%, 0.15% or 0.2%, etc., or it can be a range consisting of any of the above values.

[0069] The test method for the type and content of residual lithium in this application is: accurately weigh 5.0000g of the sample to be tested in a 150.0mL beaker, and the sample mass is recorded as m 样品 . Add 100.0g pure water and a stirring magnet to the beaker of the sample to be tested, seal it with plastic wrap, and place it on a magnetic stirrer to stir. Use a dry suction filtration device to filter the sample solution in the above step to obtain a filtrate. In a 100.0mL beaker, add a stirring magnet, accurately weigh 60.0000g of the filtrate for titration, record it as m 滤液 Titrate the filtrate to the endpoint with 0.1000mol / L hydrochloric acid standard solution. When the test is finished and the number of jump points is 2, record the volume V corresponding to the jump points EP1 and EP2. 正1 、V 正2 ; When the test is finished and the number of jump points is 3, record the volume V corresponding to the jump points EP1, EP2, and EP3 正1 、V 正2 、V正3 The titrated solution was titrated with 0.1000 mol / L sodium hydroxide standard solution to the endpoint, and the volume V corresponding to the jump points EP1 and EP2 was recorded. 反1 、V 反2 、V 反3 According to the results of forward and reverse titration, the corresponding types and contents of residual lithium can be calculated in combination with Table 1.

[0070] Table 1

[0071] Table 2

[0072] The second aspect of the present application provides a method for preparing the solid electrolyte material of the first aspect of the present application, comprising: 2 Source, M 3 Source, PO4 3- The first precursor is obtained by mixing the source, precipitant and solvent, co-precipitating and filtering; the first precursor, M 1 The source and the R source are mixed and sintered for the first time in an oxygen-containing atmosphere to obtain a second precursor; the second precursor, the Li source, the P2O7 4- The solid electrolyte material is prepared by mixing the solid electrolyte material with the solid electrolyte material and performing a second sintering in an oxygen-free atmosphere. The solid electrolyte material prepared by this method thus possesses all the characteristics and advantages of the aforementioned solid electrolyte materials, which will not be elaborated here. In general, it has at least the advantages of high ionic conductivity and good structural stability.

[0073] The method is described in detail below. Referring to FIG1 , the method includes:

[0074] S100: M 2 Source, M 3 Source, PO4 3- Source mixing to prepare the first precursor

[0075] According to some embodiments of the present application, M 2 Source, M 3 Source, PO4 3- The source, precipitant and solvent are mixed, and the first precursor is obtained after co-precipitation and filtration.

[0076] According to some embodiments of the present application, the M 2 Source, the M 3 Source, the PO4 3-The first precursor is obtained by mixing a source, a surfactant, the precipitant, and the solvent, co-precipitating, and filtering. Thus, by adding the surfactant, the formation energy of the preferred crystal plane can be reduced, the proportion of the preferred crystal plane corresponding to the lithium ion transmission channel can be increased, and the lithium ion transmission rate can be increased, ultimately improving the ionic conductivity of the solid electrolyte material.

[0077] According to some embodiments of the present application, based on the PO4 3 -The total mass of the source, the mass proportion of the surfactant can be greater than or equal to 0.1%, for example, it can be 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1%, 1.5% or 2%, or it can be a range composed of any of the above values. Therefore, by making the type of surfactant within the above range, the proportion of the dominant crystal plane can be increased, the transmission rate of lithium ions can be increased, and the ionic conductivity of the solid electrolyte material can be improved. According to some specific embodiments of the present application, based on the PO4 3 -The total mass of the source, the mass proportion of the surfactant can be 0.1%-1%. According to other specific embodiments of the present application, based on the PO4 3 -The total mass of the source, the mass proportion of the surfactant can be 0.3%-0.7%.

[0078] According to some embodiments of the present application, the surfactant includes at least one of polyvinyl pyrrolidone, sodium dodecylbenzenesulfonate, and a sulfonate. Thus, by selecting the above surfactants, the formation energy of the dominant crystal planes corresponding to the lithium ion transmission channels can be reduced, the proportion of the dominant crystal planes can be increased, and the lithium ion transmission rate can be increased, ultimately improving the ionic conductivity of the solid electrolyte material.

[0079] According to some embodiments of the present application, the M 2 Sources include M 2 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate.

[0080] According to some embodiments of the present application, the M 3 Sources include M 3 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate.

[0081] According to some embodiments of the present application, the PO4 3- The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4.

[0082] According to some embodiments of the present application, the precipitant includes at least one of sodium hydroxide, sodium carbonate, and ammonia water.

[0083] According to some embodiments of the present application, the solvent includes at least one of pure water, alcohols, and ethers.

[0084] S200: Mix the first precursor and R source and perform the first sintering to obtain the second precursor.

[0085] According to some embodiments of the present application, the first precursor and the R source are mixed and sintered for the first time in an oxygen-containing atmosphere to obtain a second precursor.

[0086] According to some embodiments of the present application, the oxygen-containing atmosphere includes oxygen or air.

[0087] According to some embodiments of the present application, the temperature of the first sintering may be 700° C.-900° C., and the time of the first sintering may be 4 h-10 h.

[0088] As an example, the temperature of the first sintering may be 700° C., 750° C., 800° C., 850° C., or 900° C., or may be any range thereof.

[0089] As an example, the first sintering time may be 4 hours to 10 hours, for example, 4 hours, 6 hours, 8 hours or 10 hours, or may be within a range consisting of any of the above values.

[0090] Therefore, by setting the temperature and time of the first sintering within the above ranges, a phosphate-heteropolyacid composite precursor with high purity and stable structure can be formed, and the particles are kept within a limited range, thereby maintaining a high ionic conductivity.

[0091] According to some embodiments of the present application, the M 1 Sources include M 1 At least one of oxides, phosphates, sulfates, chlorides, nitrates, and carbonates.

[0092] According to some embodiments of the present application, the R source includes at least one of a simple substance, an oxide, and a hydride containing R.

[0093] S300: The second precursor, Li source, M 1 Source, P2O7 4 -Source mixture is sintered for the second time in an oxygen-free atmosphere

[0094] According to some embodiments of the present application, the second precursor, Li source, M 1 Source, P2O7 4The source mixture is sintered for the second time in an oxygen-free atmosphere.

[0095] According to some embodiments of the present application, the temperature of the second sintering may be 450° C.-700° C., and the time of the second sintering may be 8 h-20 h.

[0096] As an example, the temperature of the second sintering may be 450° C., 500° C., 550° C., 600° C., 650° C., or 700° C., or may be within a range consisting of any of the above values.

[0097] As an example, the second sintering time is 8 hours to 20 hours, for example, 8 hours, 10 hours, 12 hours, 14 hours, 16 hours, 18 hours or 20 hours, or a range consisting of any of the above values.

[0098] Therefore, by setting the temperature and time of the second sintering within the above ranges, the formation of a phosphate-heteropolyacid-pyrophosphate composite phase with high purity and stable structure can be ensured, and the particles are kept within a limited range, thereby maintaining a high ionic conductivity.

[0099] According to some embodiments of the present application, the oxygen-free atmosphere includes an inert gas or nitrogen. Thus, by performing the second sintering in an oxygen-free atmosphere, the probability of pyrophosphate being converted into phosphate can be reduced, thereby increasing the pyrophosphate content in the solid electrolyte material.

[0100] According to some embodiments of the present application, the P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7.

[0101] According to some embodiments of the present application, the Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate.

[0102] According to some embodiments of the present application, the method may further include performing nano-processing on the solid electrolyte material.

[0103] As an example, the solid electrolyte material may be nano-processed by ball milling.

[0104] According to some embodiments of the present application, the nano-processing may include: mixing the solid electrolyte material with a solvent to form a slurry, performing sand milling, drying, and dissociation to obtain a nano-scale solid electrolyte material.

[0105] As an example, the mass proportion of the solid electrolyte material in the slurry can be 10%-70%, for example, 10%, 20%, 30%, 40%, 50%, 60% or 70%, or a range consisting of any of the above values. According to some specific embodiments of the present application, the mass proportion of the solid electrolyte material in the slurry can be 30%-60%.

[0106] According to some embodiments of the present application, the drying temperature may be 80°C-400°C, for example, 80°C, 100°C, 150°C, 200°C, 250°C, 300°C, 350°C or 400°C, or may be within the range of any of the above values. According to some specific embodiments of the present application, the first drying

[0107] According to some embodiments of the present application, the drying time may be 0.1 h-10 h, for example, 0.1 h, 1 h, 3 h, 5 h, 7 h, 9 h or 10 h, or a range of any of the above values. According to some embodiments of the present application, the drying time may be 0.5 h-3 h.

[0108] According to some embodiments of the present application, the drying equipment may include at least one of a spray dryer, a fluidized bed dryer, a belt dryer, and a flash dryer.

[0109] According to some embodiments of the present application, the average particle size of the nanosized solid electrolyte material may be less than or equal to 200 nm, specifically, may be 5 nm-100 nm.

[0110] According to some embodiments of the present application, the dissociation equipment may include at least one of a jet mill, a mechanical mill, and a colloid mill.

[0111] The third aspect of the present application provides a positive electrode active material, comprising the solid electrolyte material provided in the first aspect of the present application or the solid electrolyte material prepared by the method provided in the second aspect of the present application.

[0112] According to some embodiments of the present application, the positive electrode active material includes a substrate, and at least a portion of the surface of the substrate has a coating layer, and the coating layer includes the solid electrolyte material. Thus, by forming the solid electrolyte material on at least a portion of the surface of the substrate, the ionic conductivity of the positive electrode active material can be improved due to the high ionic conductivity of the solid electrolyte material, thereby improving the rate performance of the battery.

[0113] According to some embodiments of the present application, the mass proportion of the solid electrolyte material based on the total mass of the matrix can be 0.05%-1%. For example, it can be 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, etc., or it can be a range composed of any of the above values. Therefore, by making the content of the solid electrolyte material within the above range, the ionic conductivity of the positive electrode active material can be improved, thereby improving the rate performance of the battery.

[0114] The fourth aspect of the present application provides a positive electrode plate, comprising the positive electrode active material provided by the third aspect of the present application.

[0115] The fifth aspect of the present application provides a solid-state battery, comprising the positive electrode sheet provided in the fourth aspect of the present application.

[0116] The sixth aspect of the present application provides an electrical device, including the solid-state battery provided in the fifth aspect of the present application.

[0117] Example 1

[0118] Aluminum nitrate, titanyl sulfate, and disodium hydrogen phosphate were mixed according to the molar ratio of Al 3+ :Ti 4+ :PO4 3 -=0.3:1.7:1.5 in pure water, add PVP (polyvinyl pyrrolidone) surfactant, based on the total mass of disodium hydrogen phosphate, the mass proportion of PVP is 0.5%, heat to 60 ° C and stir for 30 minutes to form a uniform precipitate, and obtain the powder of the first precursor after filtration and drying.

[0119] The first precursor and silicon dioxide are mixed according to Si 4+ :PO4 3 The two precursors were weighed in a ratio of 1:1:1.5 and mixed evenly in a high-speed mixer, and sintered at 800° C. for 6 hours in an air atmosphere to obtain a powder of the second precursor.

[0120] The second precursor and lithium carbonate, potassium carbonate, titanium pyrophosphate are mixed according to Li + :K + :P2O7 4 -:PO4 3- =0.6:0.2:0.5:1.5 ratio was weighed and mixed evenly in a high-speed mixer, and sintered at 550° C. for 12 hours in a nitrogen atmosphere to obtain a micron-sized composite oxide solid electrolyte material.

[0121] The obtained micron-sized composite oxide solid electrolyte material was added into pure water to prepare a slurry with a solid content of 50%. The slurry was milled with zirconium oxide balls in a ball mill for 6 hours to obtain a nano-slurry with an average particle size of less than 200 nm. The powder was treated with a spray dryer to obtain a powder. The powder was dissociated and sieved to obtain a relatively uniform particle size distribution with a composition of Li 0.6 K 0.2 Al 0.3 Ti 1.7 (SiO3)(P2O7) 0.5 (PO4) 1.5 solid electrolyte nanopowder.

[0122] The preparation methods of Examples 2 to 11, Comparative Examples 2, 3 and 4 are the same as those of Example 1, and the differences are detailed in Table 1.

[0123] Example 12

[0124] The preparation method is the same as that of Example 1, except that K element is not doped.

[0125] Example 13

[0126] The preparation method is the same as that of Example 1, except that K element is not doped, and the first precursor, silicon dioxide, and molybdenum trioxide are mixed according to Si 4+ :PO4 3- :Mo 6+ =0.5:1:0.5 ratio and mix well in a high speed mixer.

[0127] Example 14

[0128] The preparation method is the same as that of Example 1, except that the doped M 1 Elements are Na, M 1 The source is sodium carbonate, and M 1 Source, M 2 Source, M 3 Source, PO4 3- Source, P2O7 4- The source, R source and lithium source are weighed according to the ratio of each element in the chemical formula.

[0129] Example 15

[0130] The preparation method is the same as that of Example 1, except that the doped M 2 Elements are Y, M 2 The source is yttrium oxide, and M 1 Source, M 2 Source, M 3 Source, PO4 3- Source, P2O7 4- The source, R source and lithium source are weighed according to the ratio of each element in the chemical formula.

[0131] Example 16

[0132] The preparation method is the same as that of Example 1, except that the doped M 3 Elements are Zr, M 2 The source is zirconium oxide, and M 1 Source, M 2 Source, M 3 Source, PO4 3- Source, P2O7 4- The source, R source and lithium source are weighed according to the ratio of each element in the chemical formula.

[0133] Example 17

[0134] The preparation method is the same as that of Example 1, except that the R source is molybdenum oxide, and during the preparation process, M 1 Source, M 2 Source, M 3 Source, PO4 3- Source, P2O7 4- The source, R source and lithium source are weighed according to the ratio of each element in the chemical formula.

[0135] Comparative Example 1

[0136] (1) Li2CO3, MgCO3, Al2O3, TiO2, ZrO2, and NH4H2PO4 compounds were weighed according to a stoichiometric ratio, a certain amount of pure water was added and mixed, and then the mixture was mixed and crushed in a ball mill to obtain a mixed slurry A with a solid content of 50%; 55% by weight of acrylamide (monomer), (NH4)2S2O8 (initiator), and TEMED (catalyst) were added to the mixed slurry A and uniformly dispersed in a stirring device to obtain a mixed slurry B;

[0137] (2) pouring the mixed slurry B into a sagger container and drying it in a blast oven at 100° C. to initiate a polymerization reaction of the substances in the mixed slurry B, and obtaining a bulk solid electrolyte precursor A after 12 hours;

[0138] (3) The solid electrolyte precursor A obtained in step (2) was pre-sintered at 550° C. in a muffle furnace for 2 hours, and the sintered product was crushed in a wall breaker at the highest level for 5 minutes to obtain a powdered solid electrolyte precursor B.

[0139] (4) The solid electrolyte precursor B obtained in step (3) was sintered in a muffle furnace at 800°C for 6 hours, and the sintered product was crushed in a jet mill to obtain a powdery, micron-sized solid electrolyte Li 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti1.65 (PO4)3.

[0140] (5) The solid electrolyte Li obtained in step (4) 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3 was mixed with pure water in a sand mill at 1000 rpm for 2 hours to obtain a nanoscale slurry with a solid content of 50%. The slurry was freeze-dried and the powder obtained after drying was further dissociated by a jet mill to obtain a powdery, nanoscale solid electrolyte material Li 1.2 Mg 0.05 Al 0.3 Zr 0.05 Ti 1.65 (PO4)3.

[0141] Preparation method of button battery: the positive electrode material NCM811 (LiNi 0.8 Co 0.1 Mn 0.1 O2), solid electrolyte, acetylene black, and polyvinylidene fluoride (PVDF) were mixed in a mass ratio of 90:2:3:5, coated on aluminum foil, and dried. The cathode was then stamped using a pressure of 100 MPa into a 12 mm diameter, 120 μm thick positive electrode sheet. The positive electrode sheet was then dried in a vacuum oven at 120°C for 12 hours. A 17 mm diameter, 1 mm thick lithium metal sheet was used as the negative electrode; a 25 μm thick Celgard 2400 porous membrane was used as the separator; and the electrolyte was a mixture of equal parts 1 mol / L LiPF6, ethylene carbonate (EC), and diethyl carbonate (DEC). The positive electrode sheet, separator, negative electrode sheet, and 4 μL of electrolyte were assembled into a 2025-type button cell in an Ar glove box with water and oxygen concentrations below 5 ppm.

[0142] Performance testing methods

[0143] 1. Test method for ionic conductivity of solid electrolyte materials

[0144] The ionic conductivity test method is to form 5 mg of nanopowder of solid electrolyte material into a sheet sample at a pressure of 200 MPa in a steel mold with a diameter of 12 mm, and then place the formed sheet sample in a fixture to perform AC impedance testing on an electrochemical workstation to obtain the ionic conductivity.

[0145] 2. Solid electrolyte structural stability test method

[0146] Take 5g of solid electrolyte material powder, place it in a beaker of 95g of pure water, stir and heat to 100℃ and keep warm for 5 minutes, then cool the beaker naturally to room temperature and filter it. Titrate the filtrate with standard hydrochloric acid solution to obtain the lithium content in the filtrate.

[0147] 3. XRD test method

[0148] The X-ray diffraction test method is to use an X-ray automatic diffractometer for phase and crystal structure analysis, with an operating voltage of 40 kV, an operating current of 250 mA, continuous scanning, a scanning speed of 4° / min, a step size of 0.02°, and a scanning angle of 10°-80°.

[0149] 4. Battery rate performance test method

[0150] The assembled battery was tested at 0.1C and 1C rates, and the ratio of the capacity at 1C rate to the capacity at 0.1C rate was calculated.

[0151] 5. Battery interface impedance test method

[0152] The assembled battery was measured in the electrochemical workstation using the AC impedance mode.

[0153] The test results of the batteries in Examples 1 to 17 and Comparative Examples 1 to 4 are shown in Table 2.

[0154] Conclusion: Comparison of Examples 1-17 with Comparative Examples 1-4 shows that the solid electrolyte material proposed in this application has both high ionic conductivity and low Li content in the filtrate. Batteries containing the solid electrolyte material proposed in this application have excellent rate performance and low interfacial impedance. This indicates that by using phosphate, pyrophosphate, and heteropolyacids as the skeleton of the solid electrolyte material, the carrier mobility can be increased. During carrier mobility, the probability of phase transition in the crystal structure can be reduced, thereby improving the structural stability of the solid electrolyte material and improving the intrinsic ionic conductivity of the solid electrolyte material.

[0155] It can be seen from Examples 1 to 4 that by adding different amounts of pyrophosphate to the solid electrolyte material, the mobility of carriers can be increased and the ionic conductivity of the solid electrolyte material can be improved.

[0156] It can be seen from the comparison between Example 5 and Examples 1-4 and 6-17 that, in the process of preparing the solid electrolyte material, by adding a surfactant, the content of the dominant crystal face 113 can be increased, thereby increasing the lithium ion transmission rate and improving the ionic conductivity of the solid electrolyte material.

[0157] It can be seen from Examples 6 to 11 that, in the process of preparing the solid electrolyte material, by adding surfactants of different masses, the content of the dominant crystal face 113 in the solid electrolyte material can be adjusted, thereby increasing the lithium ion transmission rate and improving the ionic conductivity of the solid electrolyte material.

[0158] It can be seen from the comparison of Examples 1 to 17 and Comparative Example 3 that by adopting a double sintering process, a solid electrolyte material having both hexagonal and monoclinic crystal systems can be formed, and the binding of anions to lithium ions can be weakened during lithium ion transmission, thereby improving the ionic conductivity of the solid electrolyte material.

[0159] It can be seen from Examples 13 to 17 that different types of M can be doped into the solid electrolyte material. 1 Elements, M 2 Elements, M 3 element.

[0160] As can be seen in Figure 2, the XRD spectrum shows characteristic diffraction peaks for phosphate, pyrophosphate, and silicate, indicating that the solid electrolyte material prepared in Example 3 contains phosphate, pyrophosphate, and heteropolyacid. The ratio of I(113) to I(104) is greater than 2, indicating a high content of 113 crystal planes, which can increase the transport channels for lithium ions, increase the lithium ion transport rate, and thus improve the ionic conductivity of the solid electrolyte material.

[0161] As can be seen from FIG3 , the XRD spectrum shows characteristic diffraction peaks for phosphate, pyrophosphate, and silicate, indicating that the solid electrolyte material prepared in Example 5 contains phosphate, pyrophosphate, and heteropolyacid. The ratio of I(113) to I(104) is less than 2, so the content of 113 crystal planes in the solid electrolyte material in Example 5 is less than that in Example 3, and there are fewer lithium ion transmission channels, so the ionic conductivity of the solid electrolyte material is lower than that in Example 3.

[0162] As can be seen in FIG4 , the XRD spectrum contains only characteristic diffraction peaks of phosphate groups, indicating that the solid electrolyte material in Comparative Example 1 contains only phosphate groups. The ratio of I(113) to I(104) is less than 2, so the solid electrolyte material in Comparative Example 1 has a low content of 113 crystal planes, fewer lithium ion transmission channels, and therefore low ionic conductivity of the solid electrolyte.

[0163] As can be seen from Figure 5, the XRD spectrum shows the presence of characteristic diffraction peaks for phosphate, pyrophosphate, and silicate, indicating that the solid electrolyte material prepared in Example 2 contains phosphate, pyrophosphate, and heteropolyacid. The ratio of I(113) to I(104) is greater than 2, so the content of 113 crystal planes is relatively high, which can increase the transmission channel of lithium ions, increase the transmission rate of lithium ions, and thus improve the ionic conductivity of the solid electrolyte. The XRD spectrum shows the presence of characteristic diffraction peaks for both the hexagonal phase and the monoclinic phase, which can weaken the binding of anions during lithium ion transmission and further improve the ionic conductivity of the solid electrolyte material.

[0164] As can be seen from FIG. 6 , the solid electrolyte material prepared in Example 2 can be discharged.

[0165] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, "plurality" means two or more, unless otherwise specifically specified.

[0166] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0167] Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limitations on the present application. Ordinary technicians in this field can change, modify, replace and modify the above embodiments within the scope of the present application.

Claims

1. A solid electrolyte material, characterized in that include: Li x M 1 y M 2 z M 3 u (PO4) w1 (P2O7) w2 (RO v ) w3 , Among them, M 1 including at least one of Mg, Na, and K; M 2 Including at least one of Al, Ga, In, Y, and Sc; M 3 including at least one of Ti, Zr, and Ge; R includes at least one of Mo, W, Si, Cl, Br, S, Sb, Sn, F, and P; 0<x≤5, 0≤y≤0.5, 0≤z≤1, 0≤u≤9, 0≤v≤4, 1≤w1≤3, 0<w2≤2.3, 0<w3≤3, w1+w2+w3=3; The solid electrolyte material has a NASICON crystal structure. In the X-ray diffraction spectrum of the solid electrolyte material, there are characteristic diffraction peaks at diffraction angles 2θ of 14.5°-14.8°, 19.5°-19.7°, and 22.5°-22.8°, respectively. The ratio of the peak intensity I1 of the characteristic diffraction peak at the 2θ value of 14.5°-14.8° to the peak intensity I2 of the characteristic diffraction peak at the 2θ value of 22.5°-22.8° satisfies: 1.5≤I2 / I1≤3.

2. The solid electrolyte material according to claim 1, characterized in that Meet at least one of the following conditions: M 1 including at least one of Mg or K; M 2 including at least one of Al or Y; R includes at least one of Si, Mo, or W.

3. The solid electrolyte material according to claim 1 or 2, characterized in that In the X-ray diffraction spectrum of the solid electrolyte material, there is a characteristic diffraction peak I3 at 2θ values ​​of 17.8°-18.0° and / or 23.7°-23.9° and / or 26.8°-27.0°.

4. The solid electrolyte material according to claim 3, characterized in that The X-ray diffraction spectrum of the solid electrolyte material shows that the crystal plane is along <113> Preferred orientation, the ratio of the peak intensity of the diffraction peak (113) to the diffraction peak (104) satisfies I(113) / I(104)≥2; the 2θ value corresponding to the diffraction peak (113) of the X-ray diffraction spectrum is 24.3°-24.6°, and the half-peak width range is 0.170-0.172, and the 2θ value corresponding to the diffraction peak (104) is 20.7°-20.9°, and the half-peak width range is 0.180-0.

184.

5. The solid electrolyte material according to claim 4, characterized in that 2≤I(113) / I(104)≤4.

6. The solid electrolyte material according to claim 5, characterized in that The solid electrolyte material has a charge and discharge platform at 2.4V-2.6V.

7. The solid electrolyte material according to claim 6, characterized in that Meet at least one of the following conditions: The ionic conductivity of the solid electrolyte material is greater than or equal to 1×10 -3 S / cm; The average particle size of the solid electrolyte material is 0.5 μm-20 μm; At 25°C, the pH of the solid electrolyte material is 6-10; The surface of the solid electrolyte material includes residual lithium, and the residual lithium includes at least one of dilithium hydrogen phosphate, lithium dihydrogen phosphate, lithium carbonate, and lithium pyrophosphate. Based on the total mass of the solid electrolyte material, the mass proportion of the dilithium hydrogen phosphate is a, the mass proportion of the lithium dihydrogen phosphate is b, the mass proportion of the lithium carbonate is c, and the mass proportion of the lithium pyrophosphate is d, and the following conditions are satisfied: 0≤a≤0.5%, 0≤b≤0.1%, 0≤c≤0.3%, and 0≤d≤0.2%.

8. The solid electrolyte material according to claim 7, characterized in that Meet at least one of the following conditions: The ionic conductivity of the solid electrolyte material is greater than or equal to 2×10 -3 S / cm; The average particle size of the solid electrolyte material is 0.5 μm-0.9 μm.

9. A method for preparing the solid electrolyte material according to any one of claims 1 to 8, characterized in that: include: M 2 Source, M 3 Source, PO4 3- The source, precipitant and solvent are mixed, and a first precursor is obtained after co-precipitation and filtration; Mixing the first precursor and the R source, and performing a first sintering in an oxygen-containing atmosphere to obtain a second precursor; The second precursor, Li source, M 1 Source, P2O7 4- The solid electrolyte material is obtained by mixing the solid electrolyte material with the raw materials and performing a second sintering in an oxygen-free atmosphere.

10. The method according to claim 9, characterized in that The M 2 Source, the M 3 Source, the PO4 3 -source, surfactant, the precipitant and the solvent are mixed, and the first precursor is obtained after co-precipitation and filtration.

11. The method according to claim 10, characterized in that Based on the PO4 3 - The total mass of the source, the mass of the surfactant accounts for ≥ 0.1%.

12. The method according to claim 11, characterized in that Based on the PO4 3- The mass of the surfactant accounts for 0.1%-1% of the total mass of the source.

13. The method according to claim 12, characterized in that Based on the PO4 3- The mass of the surfactant accounts for 0.3%-0.7% of the total mass of the source.

14. The method according to claim 10, characterized in that The surfactant includes at least one of polyvinyl pyrrolidone, sodium dodecylbenzene sulfonate, and sulfonates.

15. The method according to claim 9 or 10, characterized in that Meet at least one of the following conditions: The oxygen-containing atmosphere includes oxygen or air; The temperature of the first sintering is 700° C.-900° C., and the time of the first sintering is 4 h-10 h; The oxygen-free atmosphere includes an inert gas or nitrogen; The temperature of the second sintering is 450°C-700°C, and the time of the second sintering is 8h-20h; The M 1 Sources include M 1 At least one of oxides, phosphates, sulfates, chlorides, nitrates, and carbonates; The M 2 Sources include M 2 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate; The M 3 Sources include M 3 At least one of phosphate, acetate, sulfate, chloride, nitrate, and carbonate; The PO4 3- The source includes at least one of H3PO4, NH4H2PO4, (NH4)2HPO4, (NH4)3PO4, LiH2PO4, Li2HPO4, Li3PO4, NaH2PO4, Na2HPO4, and Na3PO4; The Li source includes at least one of lithium carbonate, lithium hydroxide, and lithium nitrate; The P2O7 4- The source includes at least one of H4P2O7, (NH4)2H2P2O7, Li2H2P2O7, and Li4P2O7; The R source includes at least one of a simple substance, an oxide, and a hydride containing R; The precipitant includes at least one of sodium hydroxide, sodium carbonate and ammonia water.

16. A positive electrode active material, characterized in that The invention comprises the solid electrolyte material according to any one of claims 1 to 8 or the solid electrolyte material prepared by the method according to any one of claims 9 to 15.

17. The positive electrode active material according to claim 16, characterized in that The positive electrode active material includes a matrix, at least a portion of the surface of the matrix has a coating layer, and the coating layer includes the solid electrolyte material.

18. The positive electrode active material according to claim 17, characterized in that Based on the total mass of the matrix, the mass proportion of the solid electrolyte material is 0.05%-1%.

19. A positive electrode plate, characterized in that: The positive electrode active material comprises the positive electrode active material according to any one of claims 16 to 18.

20. A solid-state battery, characterized in that: Including the positive electrode sheet according to claim 19.

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