Solid-state electrolyte and preparation method thereof, solid-state battery and electric device

Abstract

The application discloses a kind of solid electrolyte and preparation method thereof, solid-state battery and electric equipment;The preparation method of the solid electrolyte includes the following steps: S1, under inert gas atmosphere, lithium bromide, metal bromide and solvent are mixed to carry out reaction, after solid-liquid separation, grinding is carried out, to obtain precursor;S2, the precursor is sequentially annealed I and annealing II;Obtain intermediate;S3, intermediate and lithium halide are mixed to carry out ball milling, to obtain solid electrolyte;The temperature of annealing II is greater than the temperature of annealing I;The annealing temperature of annealing II is ≤400 DEG C.The solid electrolyte and electrode will generate a layer of self-adapting interface layer with high ionic conductivity in situ, and effectively fill the original gap between electrode and solid electrolyte and the new gap generated by lithium stripping, so as to eliminate the defect of high impedance caused by poor interface contact, and can inhibit the formation of lithium dendrite, and then improve its electrochemical performance applied to solid-state battery.

Description

Technical Field

[0001] This invention relates to the field of electrolyte technology, and in particular to a solid electrolyte, its preparation method, solid-state battery, and electrical device. Background Technology

[0002] With the rapid development of electric vehicles and portable electronic devices, high-energy-density and high-safety rechargeable batteries have become a research hotspot. All-solid-state lithium batteries, by using non-flammable solid electrolytes instead of traditional organic liquid electrolytes, fundamentally solve safety issues such as battery leakage and combustion, while also possessing higher operating voltage and energy density, making them an ideal choice for next-generation energy storage technology. Among these, inorganic solid electrolytes have attracted significant attention due to their high ionic conductivity, wide electrochemical window, and good thermal stability.

[0003] However, inorganic solid electrolytes still face many challenges in practical applications, especially in terms of interfacial contact with electrode materials. First, because the contact between the solid electrolyte and the electrode is solid-solid, there are inherent voids and poor contact at the interface, resulting in a significant increase in interfacial impedance, which seriously affects the rate performance and cycle life of the battery.

[0004] Furthermore, inorganic solid electrolytes typically require extremely high applied pressure (e.g., 200–400 MPa) to form effective contact with the electrodes. This not only increases the complexity and cost of battery assembly processes but also limits their integration into practical devices. Related technologies have attempted to reduce the pressing pressure by optimizing the electrolyte particle morphology, but their interface self-adaptation capabilities are insufficient, and they still cannot achieve long-term stable interface contact under low pressure.

[0005] In summary, developing an inorganic solid electrolyte that can form an adaptive interface with the electrode under low pressure, effectively fill the voids between the electrode and the electrolyte, and suppress lithium dendrite growth has significant scientific research value and practical application significance. Summary of the Invention

[0006] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the first aspect of the present invention proposes a method for preparing a solid electrolyte, wherein the solid electrolyte prepared by the method can form an adaptive interface layer during lithium stripping and effectively fill the original voids between the electrode and the solid electrolyte and the new voids generated by lithium stripping, thereby eliminating the high impedance defect caused by poor interface contact and suppressing the formation of lithium dendrites.

[0007] A second aspect of the present invention provides a solid electrolyte.

[0008] A third aspect of the present invention provides a solid-state battery.

[0009] The fourth aspect of the present invention provides an electrical appliance.

[0010] According to a first aspect of the present invention, a method for preparing a solid electrolyte is provided, comprising the following steps:

[0011] S1. Under an inert gas atmosphere, lithium bromide, metal bromide and solvent are mixed and heated, and the precursor is obtained after solid-liquid separation;

[0012] S2. Anneal the precursor sequentially through Annealing I and Annealing II to obtain the intermediate.

[0013] S3. The intermediate and lithium halide are mixed and ball-milled to obtain a solid electrolyte;

[0014] The temperature of Annealing II is greater than the temperature of Annealing I; the annealing temperature of Annealing II is ≤400℃.

[0015] According to a preferred embodiment of the present invention, the annealing temperature of annealing I is 100°C to 200°C.

[0016] According to a preferred embodiment of the present invention, the annealing time of annealing I is 20 min to 40 min.

[0017] According to a preferred embodiment of the present invention, the heating rate of the annealing I is 8~12℃ / min.

[0018] According to a preferred embodiment of the present invention, the annealing temperature of annealing II is 250°C to 400°C.

[0019] According to a preferred embodiment of the present invention, the annealing time of Annealing II is 50 min to 70 min.

[0020] According to a preferred embodiment of the present invention, the heating rate of the annealing II is 2~5℃ / min.

[0021] According to a preferred embodiment of the present invention, the metal bromide includes at least one of ferrous bromide, manganese bromide, magnesium bromide, rubidium bromide, or cesium bromide.

[0022] According to a preferred embodiment of the present invention, the lithium halide includes at least one of lithium fluoride, lithium chloride, lithium bromide or lithium iodide.

[0023] According to a preferred embodiment of the present invention, in step S1, the molar ratio of lithium bromide to metal bromide is 1:(0.1~3).

[0024] According to a preferred embodiment of the present invention, in step S3, the molar ratio of the intermediate to lithium halide is 1:(0.1~0.4).

[0025] According to a preferred embodiment of the present invention, the inert gas includes at least one of nitrogen, argon, or helium.

[0026] According to a preferred embodiment of the present invention, in step S1, the reaction temperature is 40°C to 50°C.

[0027] According to a preferred embodiment of the present invention, in step S1, the reaction time is 2h to 4h.

[0028] According to a preferred embodiment of the present invention, in step S1, the solid-liquid separation method includes low-temperature freeze drying.

[0029] According to a preferred embodiment of the present invention, the solvent includes at least one of acetonitrile, acetone, tetrahydrofuran, or ethyl acetate.

[0030] The method for preparing solid electrolytes according to embodiments of the present invention has at least the following beneficial effects:

[0031] This invention first chemically combines lithium bromide and metal bromide using a solvent method to obtain a precursor, which is then annealed in stages I and II to obtain an intermediate. The intermediate and lithium halide are then ball-milled to obtain a solid electrolyte. During lithium stripping, the controlled migration of halide ions in the solid electrolyte causes an adaptive interface layer with high ionic conductivity to be generated in situ between the solid electrolyte and the electrode. This layer effectively fills the original voids between the electrode and the solid electrolyte, as well as the new voids generated by lithium stripping, thereby eliminating the high impedance defect caused by poor interface contact and suppressing the formation of lithium dendrites, thus improving the electrochemical performance of solid-state batteries.

[0032] Furthermore, the addition of metal bromides serves two purposes: firstly, to facilitate the preparation of solid electrolytes, and secondly, to provide higher ionic conductivity and reduce interfacial impedance.

[0033] Furthermore, the present invention ball-mills the intermediate and lithium halide so that during electrochemical cycling, the halide ions added by physical ball milling will migrate between the anode and the solid electrolyte, thereby dynamically constructing an adaptive solid electrolyte interface, effectively alleviating the problem of high interfacial impedance caused by voids, and also suppressing dendrite formation.

[0034] Furthermore, when the temperatures of Annealing II and Annealing I meet the above conditions, on the one hand, lithium evaporation during high-temperature annealing can be avoided, thereby reducing the lithium content, destroying the crystal structure, and causing a decrease in electrochemical performance; on the other hand, it is conducive to the formation of amorphous phase, which is beneficial to promoting lithium-ion conduction.

[0035] According to a second aspect of the present invention, a solid electrolyte is provided, which is prepared by the method for preparing the solid electrolyte described in the first aspect of the present invention.

[0036] According to a preferred embodiment of the present invention, the solid electrolyte has the chemical formula Li. a+d M b Br c X d ;in,

[0037] M is at least one of iron, manganese, rubidium, and cesium;

[0038] X is at least one of fluorine, chlorine, bromine, and iodine;

[0039] The values ​​of a, b, and c are all integers greater than 0, and 0.1 ≤ d ≤ 0.4.

[0040] According to a preferred embodiment of the present invention, the ball milling conditions satisfy at least one of the following:

[0041] i. 1~5mm zirconia microspheres;

[0042] ii. Ball-to-material ratio (3~6):1;

[0043] iii. Rotation speed 400~800 rpm;

[0044] iiii. Ball milling time: 6-12 hours.

[0045] A third aspect of the present invention provides a solid-state battery comprising the solid electrolyte described in the second aspect of the present invention.

[0046] A fourth aspect of the present invention provides an electrical device comprising the solid-state battery described in the third aspect of the present invention.

[0047] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0048] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0049] Figure 1 This is a cross-sectional SEM image of the electrode-electrolyte interface at the experimental battery prepared in Example 1 of this invention after cycling.

[0050] Figure 2 This is a cross-sectional SEM image of the electrode-electrolyte interface at the experimental battery prepared in Comparative Example 2 of this invention after cycling. Detailed Implementation

[0051] The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described in conjunction with the embodiments, but the present invention is not limited to these embodiments.

[0052] Unless otherwise specified, the reagents, methods and equipment used in this invention are all conventional reagents, methods and equipment in this technical field.

[0053] In some embodiments of the present invention, a method for preparing a solid electrolyte is provided, comprising the following steps:

[0054] S1. Under an inert gas atmosphere, lithium bromide, metal bromide and solvent are mixed and heated, and the precursor is obtained after solid-liquid separation;

[0055] S2. Anneal the precursor sequentially through Annealing I and Annealing II to obtain the intermediate.

[0056] S3. The intermediate and lithium halide are mixed and ball-milled to obtain the solid electrolyte;

[0057] The annealing temperature of Annealing II is greater than that of Annealing I; the annealing temperature of Annealing II is ≤400℃.

[0058] Understandably, this invention first chemically combines lithium bromide and metal bromide using a solvent method to obtain a precursor, which is then annealed in stages I and II to obtain an intermediate. The intermediate and lithium halide are then ball-milled to obtain a solid electrolyte. During lithium stripping, the controlled migration of halide ions in this solid electrolyte causes the generation of an adaptive interface layer with high ionic conductivity between the electrolyte and the electrode in situ. This layer effectively fills the original voids between the electrode and the solid electrolyte, as well as the new voids generated by lithium stripping, thereby eliminating the high impedance defect caused by poor interface contact and suppressing the formation of lithium dendrites, thus improving the electrochemical performance of solid-state batteries.

[0059] Furthermore, the present invention ball-mills the intermediate and lithium halide so that during electrochemical cycling, the halide ions added by physical ball milling will migrate between the anode and the solid electrolyte, thereby dynamically constructing an adaptive solid electrolyte interface, effectively alleviating the problem of high interfacial impedance caused by voids, and also suppressing dendrite formation.

[0060] In some embodiments of the present invention, the annealing temperature of annealing I is 100°C to 200°C. For example, it includes 100°C, 120°C, 140°C, 150°C, 155°C, 160°C, 165°C, 180°C, 200°C, or any sub-range consisting of any two of the above values.

[0061] In some embodiments of the present invention, the annealing time for Annealing I is 20 min to 40 min. For example, it includes 22 min, 24 min, 26 min, 28 min, 30 min, 32 min, 34 min, 36 min, 38 min, 40 min, or any sub-range consisting of any two of the above values.

[0062] In some embodiments of the present invention, the heating rate of annealing I is 8~12℃ / min. For example, it includes a sub-range of 8℃ / min, 9℃ / min, 10℃ / min, 11℃ / min, 12℃ / min, or any two of the above values.

[0063] In some embodiments of the present invention, the annealing temperature of Annealing II is 250°C to 400°C. For example, it includes 250°C, 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, or any sub-range consisting of any two of the above values.

[0064] Therefore, when the temperature of Annealing II is within the above range, on the one hand, lithium evaporation during high-temperature annealing can be avoided, thereby reducing the lithium content, destroying the crystal structure, and causing a decrease in electrochemical performance; on the other hand, it is conducive to the formation of amorphous phase, which is beneficial to promoting lithium-ion conduction.

[0065] In some embodiments of the present invention, the annealing time for Annealing II is 50 min to 70 min. For example, it includes 50 min, 52 min, 54 min, 56 min, 58 min, 60 min, 62 min, 64 min, 66 min, 68 min, 70 min, or any sub-range consisting of any two of the above values.

[0066] In some embodiments of the present invention, the heating rate of Annealing II is 2~5℃ / min. For example, it includes 2℃ / min, 3℃ / min, 4℃ / min, and 5℃ / min.

[0067] In some embodiments of the present invention, the metal bromide includes at least one selected from ferrous bromide, manganese bromide, magnesium bromide, rubidium bromide, or cesium bromide. Thus, the addition of the metal bromide serves two purposes: firstly, it facilitates the preparation of a solid electrolyte; secondly, it provides higher ionic conductivity and reduces interfacial impedance.

[0068] In some embodiments of the present invention, lithium halides include at least one of lithium fluoride, lithium chloride, lithium bromide, or lithium iodide.

[0069] In this way, the solid electrolyte can avoid decomposition due to reaction when it comes into physical contact with the highly reactive lithium electrode, effectively ensuring that the solid electrolyte has good ionic conductivity. Furthermore, the directional migration of halide anions between the anode and the solid electrolyte can construct an adaptive solid electrolyte interface, effectively alleviating the problem of high interfacial impedance caused by voids and suppressing dendrite formation.

[0070] In some embodiments of the present invention, in step S1, the molar ratio of lithium bromide to metal bromide is 1:(0.1~3). For example, it includes sub-ranges such as 1:0.1, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1.0, 1:1.5, 1:1.8, 1:2, 1:2.4, 1:2.6, 1:2.8, 1:3, or any two of the above ratios.

[0071] In some embodiments of the present invention, in step S3, the molar ratio of the intermediate to lithium halide is 1:(0.1~0.4). For example, it includes sub-ranges of 1:0.1, 1:0.2, 1:0.3, 1:0.4, or any two of the above ratios.

[0072] In some embodiments of the present invention, the inert gas includes at least one of nitrogen, argon, or helium.

[0073] In some embodiments of the present invention, the reaction temperature in step S1 is 40°C to 50°C. For example, it includes 40°C, 42°C, 44°C, 46°C, 48°C, 50°C, or any sub-range consisting of any two of the above values.

[0074] In some embodiments of the present invention, the reaction time in step S1 is 2 hours to 4 hours. For example, it may be 2 hours, 3 hours, or 4 hours.

[0075] In some embodiments of the present invention, in step S1, the solid-liquid separation method includes low-temperature freeze drying, where low temperature refers to a temperature ≤-40°C.

[0076] In some embodiments of the present invention, in step S1, the precursor obtained after solid-liquid separation may further undergo a grinding step. This is more beneficial for subsequent annealing experiments.

[0077] In some embodiments of the present invention, the solvent includes at least one of acetonitrile, acetone, tetrahydrofuran, or ethyl acetate.

[0078] In some embodiments of the present invention, the ball milling conditions satisfy at least one of the following:

[0079] i. 1~5mm zirconia microspheres;

[0080] ii. Ball-to-material ratio (3~6):1;

[0081] iii. Rotation speed 400~800 rpm;

[0082] iiii. Ball milling time: 6-12 hours.

[0083] In some embodiments of the present invention, in step S2, after annealing II, the intermediate is further ground through a 300-500 mesh sieve to obtain the intermediate.

[0084] In some embodiments of the present invention, the present invention provides a solid electrolyte, which is prepared by the solid electrolyte preparation method of the first aspect of the present invention.

[0085] Thus, an adaptive interface layer with high ionic conductivity is generated in situ between the solid electrolyte and the electrode in this invention, which effectively fills the original voids between the electrode and the solid electrolyte and the new voids generated by lithium stripping, thereby eliminating the high impedance defect caused by poor interface contact and suppressing the formation of lithium dendrites, thereby improving the electrochemical performance of solid-state batteries.

[0086] In some embodiments of the present invention, the chemical formula of the solid electrolyte is Li. a+d M b Br c X d ;in,

[0087] M is at least one of iron, manganese, rubidium, and cesium;

[0088] X is at least one of fluorine, chlorine, bromine, and iodine;

[0089] The values ​​of a, b, and c are all integers greater than 0, and 0.1 ≤ d ≤ 0.4.

[0090] In some embodiments of the present invention, the present invention provides a solid-state battery including the solid-state electrolyte described herein.

[0091] Therefore, the solid-state battery has all the beneficial effects of the solid electrolyte of the present invention, and further, the solid-state battery has the characteristics of high specific capacity, high cycle performance and high critical current density.

[0092] In some embodiments of the present invention, the present invention provides an electrical device including the solid-state battery described herein.

[0093] It is understood that the aforementioned electrical equipment includes any device, apparatus, or system that uses the aforementioned solid-state batteries, including but not limited to: laptops, pen-based computers, mobile computers, e-book players, portable telephones, portable fax machines, portable copiers, portable printers, stereo headphones, video recorders, LCD TVs, portable cleaners, portable CD players, mini CDs, transceivers, electronic notebooks, calculators, memory cards, portable recorders, radios, backup power supplies, motors, automobiles, motorcycles, electric bicycles, bicycles, lighting fixtures, toys, game consoles, clocks, power tools, flashlights, cameras, and large household batteries, etc.

[0094] All electrochemical performance tests below were performed using CHI660F.

[0095] Example 1

[0096] This example provides a solid electrolyte Li 2.35 FeBr 4.35 The specific preparation steps are as follows:

[0097] S1. Lithium bromide and ferrous bromide in a molar ratio of 2:1 were added to the reactor, acetonitrile was added as solvent, the mixture was heated to 45°C under an argon atmosphere, stirred for 8 hours, and then freeze-dried at low temperature and ground to obtain the precursor.

[0098] S2. Place the precursor in a tube furnace and perform Annealing I and Annealing II under an argon atmosphere:

[0099] Annealing I: Heating rate 10℃ / min, annealing temperature 150℃, annealing time 30min;

[0100] Annealing II: After the first stage, the temperature was increased further at a rate of 5℃ / min, the annealing temperature was 300℃, and the annealing time was 60min. After the annealing, the mixture was ground and passed through a 300-mesh sieve to obtain the intermediate (Li2FeBr4).

[0101] S3. The intermediate and lithium bromide with a molar ratio of 1:0.35 are placed in a ball mill with zirconia balls for ball milling modification. The ball milling time is 12 hours and the rotation speed is 600 rpm to obtain the final product.

[0102] Example 2

[0103] This example provides a solid electrolyte Li 2.2 MnBr4F 0.2 The specific preparation steps are as follows:

[0104] S1. Lithium bromide and manganese bromide in a molar ratio of 2:1 were added to the reactor, acetone was added as a solvent, the mixture was heated to 50°C under an argon atmosphere, stirred for 8 hours, and then freeze-dried at low temperature and ground to obtain the precursor.

[0105] S2. Place the precursor in a tube furnace and perform staged annealing under an argon atmosphere:

[0106] Annealing I: Heating rate 10℃ / min, annealing temperature 150℃, annealing time 30min;

[0107] Annealing II: After the first stage, the temperature was increased further at a rate of 5℃ / min, the annealing temperature was 300℃, and the annealing time was 60min. After the annealing, the mixture was ground and passed through a 300-mesh sieve to obtain the intermediate (Li2MnBr4).

[0108] S3. The intermediate with a molar ratio of 1:0.2 and lithium fluoride are placed in a ball mill with 3mm zirconium oxide balls for ball milling modification. The ball milling time is 12h and the rotation speed is 600rpm to obtain the final product.

[0109] Example 3

[0110] This example provides a solid electrolyte Li 6.4 MgBr 8.4 The specific preparation steps are as follows:

[0111] S1. Lithium bromide and magnesium bromide in a molar ratio of 6:1 were added to the reactor, along with acetonitrile as solvent. The mixture was heated to 50°C under an argon atmosphere and stirred for 8.5 hours. After low-temperature freeze-drying, the mixture was ground to obtain the precursor.

[0112] S2. Place the precursor in a tube furnace and perform staged annealing under an argon atmosphere:

[0113] Annealing I: Heating rate 10℃ / min, annealing temperature 165℃, annealing time 30min;

[0114] Annealing II: After the first stage, the temperature was increased further at a rate of 5℃ / min, the annealing temperature was 340℃, and the annealing time was 60min. After the annealing, the product was ground and passed through a 300-mesh sieve to obtain the intermediate product (Li6MgBr8).

[0115] S3. The intermediate and lithium bromide with a molar ratio of 1:0.4 are placed in a ball mill with zirconia balls for ball milling modification. The ball milling time is 12 hours and the rotation speed is 600 rpm to obtain the final product.

[0116] Example 4

[0117] This example provides a solid electrolyte Li 2.4 MnBr 4.4The specific preparation steps are as follows:

[0118] S1. Lithium bromide and magnesium bromide in a molar ratio of 2:1 were added to the reactor, acetone was added as a solvent, the mixture was heated to 45°C under an argon atmosphere, stirred for 8 hours, and then freeze-dried at low temperature and ground to obtain the precursor.

[0119] S2. Place the precursor in a tube furnace and perform staged annealing under an argon atmosphere:

[0120] Annealing I: Heating rate 10℃ / min, annealing temperature 155℃, annealing time 30min;

[0121] Annealing II: After the first stage, the temperature was increased further at a rate of 5℃ / min, the annealing temperature was 320℃, and the annealing time was 60min. After the annealing, the mixture was ground and passed through a 300-mesh sieve to obtain the intermediate (Li2MnBr4).

[0122] S3. The intermediate and lithium bromide with a molar ratio of 1:0.4 are placed in a ball mill with zirconia balls for ball milling modification. The ball milling time is 12 hours and the rotation speed is 600 rpm to obtain the final product.

[0123] Example 5

[0124] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1. The difference is that in step S2, the annealing temperature of annealing I is 100°C.

[0125] Example 6

[0126] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1. The difference is that in step S2, the annealing temperature of annealing II is 250°C.

[0127] Example 7

[0128] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1. The difference is that in step S2, the annealing temperature of annealing II is 400°C.

[0129] Comparative Example 1

[0130] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1. The difference is that lithium bromide and ferrous bromide in step S1 are replaced with lithium chloride and ferrous chloride, and the molar ratio is adjusted to 6:1.

[0131] Comparative Example 2

[0132] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1, except that step S3 is missing.

[0133] Comparative Example 3

[0134] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1, except that annealing I is not performed in step S2.

[0135] Comparative Example 4

[0136] This example provides a solid electrolyte with the same raw materials and preparation method as in Example 1. The difference is that in step S2, the annealing temperature of annealing I is 300°C and the annealing temperature of annealing II is 150°C.

[0137] Test Example 1

[0138] First, the solid electrolytes of Examples 1-7 and Comparative Examples 1-4 of this invention were respectively prepared into experimental batteries. The specific steps are as follows:

[0139] The solid electrolyte and PVDF were mixed evenly at a weight ratio of 95:5 and solid electrolyte sheets were prepared under an external pressure of 10 MPa. The NMC sheet was used as the cathode material and lithium foil was used as the anode. The experimental battery was assembled in a dry argon-filled glove box.

[0140] Test Example 2

[0141] The solid electrolyte of Example 1 was pressed into a solid electrolyte sheet under an external pressure of 300 MPa. The NMC sheet was used as the cathode material and the lithium foil was used as the anode. The experimental battery was assembled in a dry argon-filled glove box.

[0142] The experimental batteries assembled in Test Example 1 and Test Example 2 were subjected to the following electrochemical performance tests, and the results are shown in Table 1 below.

[0143] Ionic conductivity: The AC impedance of lithium-ion batteries at room temperature was tested using a Shanghai Chenhua CHI660F electrochemical workstation with the following parameters: amplitude of 10mV and frequency range of 0.1Hz to 3MHz.

[0144] Specific capacity: Tested using a Shanghai Chenhua CHI660F electrochemical workstation, with a charge / discharge rate of 0.1C and a charge / discharge range of 2~4.8V;

[0145] Critical current density: Tested using a Shanghai Chenhua CHI660F electrochemical workstation, starting from 0.25 mA / cm². 2 Initially, 1 mAh / cm³ was deposited and stripped sequentially on one side. 2 After lithium, the current was increased to 0.5 mA / cm. 2 Maintain 1mAh / cm 2 After areal capacity deposition and stripping, sequentially at 0.25 mA / cm 2 The gradient is at 0.75 mA / cm 21.0 mA / cm 2 1.25mA / cm 2 ...up to 10mA / cm 2 The current density at which the voltage suddenly drops sharply is denoted as the critical current density.

[0146] Cycle count: Cycle testing was conducted using Wuhan Landian Battery Testing Equipment at a rate of 1 mA / cm². 2 The current density was used to perform constant current charge and discharge tests.

[0147] Table 1 Electrochemical data of the examples and comparative examples

[0148]

[0149] As shown in Table 1, the experimental batteries assembled with the solid electrolytes prepared in Examples 1-7 all exhibited high specific capacities exceeding 173 mAh / g and maintained a coulombic efficiency of over 95% after more than 1200 charge-discharge cycles, demonstrating excellent electrochemical performance that can meet actual market demands. Furthermore, Examples 1-7 all showed high (>0.80 mA / cm²) performance. 2 The solid electrolyte provides a stable interface and exhibits excellent suppression of lithium dendrites, resulting in outstanding cycling performance. Comparative Example 1, due to the replacement of lithium bromide and ferrous bromide with lithium chloride and ferrous chloride, showed a significant performance decrease. Comparative Example 2, lacking secondary ball milling modification with added lithium bromide, suffered a significant decrease in specific capacity, reaching only 138 mAh / g. The results of Comparative Example 3 demonstrate that secondary annealing effectively improves various aspects of the solid electrolyte's performance. Compared to Example 1, Test Example 2 involved preparing a solid electrolyte sheet under a pressure of 300 MPa. The results show that the solid electrolyte prepared by the technical solution provided by this invention can significantly reduce the sheet preparation pressure and exhibits superior electrochemical performance compared to the conventional control group subjected to an external pressure of 300 MPa, while effectively simplifying the production process.

[0150] Furthermore, after the experimental batteries composed of Example 1 and Comparative Example 2 of the present invention underwent charge-discharge cycles, SEM tests were performed on the cross-sections at the electrode and solid electrolyte interface. The results are as follows: Figure 1 and Figure 2 As shown; Figure 1 The left image shows the SEM map of the interface. Figure 1 The right figure shows the energy spectrum at the interface. Figure 2 The SEM image at the interface is compared with... Figure 2It can be seen that the solid electrolyte prepared in Example 1 forms a dense interface layer between the contact interface with the electrode, which effectively alleviates the problem of high interface impedance caused by poor interface contact and effectively suppresses the formation of lithium dendrites.

[0151] The present invention has been described in detail above with reference to the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method of preparing a solid-state electrolyte, characterized by, The method comprises the following steps: S1, mixing lithium bromide, metal bromide and solvent to react under inert gas atmosphere, and then separating solid and liquid to obtain a precursor; S2, sequentially performing annealing I and annealing II on the precursor to obtain an intermediate; S3, mixing the intermediate and lithium halide to perform ball milling, thereby obtaining a solid-state electrolyte; The temperature of the annealing II is higher than that of the annealing I; the annealing temperature of the annealing I is 100-200℃; and the annealing temperature of the annealing II is 250-400℃.

2. The production method according to claim 1, characterized by, The metal bromide comprises at least one of ferrous bromide, manganese bromide, magnesium bromide, rubidium bromide or cesium bromide.

3. The preparation method according to claim 1, characterized in that, The lithium halide comprises at least one of lithium fluoride, lithium chloride, lithium bromide or lithium iodide.

4. The method of claim 1, wherein, In step S1, the molar ratio of the lithium bromide to the metal bromide is 1: (0.1-3).

5. The preparation method according to claim 1, characterized in that, In step S3, the molar ratio of the intermediate to the lithium halide is 1: (0.1-0.4).

6. A solid state electrolyte, characterized by, The solid-state electrolyte is prepared by the method of any one of claims 1-5.

7. A solid state battery, characterized by The method comprises the solid-state electrolyte of claim 6.

8. An electric device, characterized by The method comprises the solid-state battery of claim 7.

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