Method for designing the composition of layered LYC compounds and recording media containing the same

Abstract

This provides a compositional design method to optimize the ionic conductivity of Li3YCl6 compounds. [Solution] A method for designing the composition of a lithium yttrium halide solid electrolyte in a hexagonal close-packed structure, comprising the steps of: calculating diffusible paths for lithium ions to move to adjacent octahedral sites in the ab-plane of each continuous layer constituting a unit cell of the hexagonal close-packed structure; calculating the active barrier energy for lithium ion diffusion for each calculated diffusion path; and calculating the occupancy rate of yttrium in the unit cell such that a percolation state is formed within the unit cell by the diffusion path with the lowest calculated active barrier energy.

Description

[Technical Field]

[0001] The present invention relates to a method for designing the composition of a solid electrolyte containing a halide, and more particularly to a method for designing the composition of a layered Li3YCl6 compound exhibiting improved ionic conductivity, and a computer-readable recording medium for implementing this method. [Background technology]

[0002] Interest in and research on semi-solid or all-solid-state batteries, which replace some or all of the liquid electrolyte with a solid electrolyte, is increasing.

[0003] However, the solid electrolyte requires excellent interfacial properties between the electrolyte layer containing it and the active material layer, as well as excellent contact properties between the solid electrolyte and the active material particles, and also excellent lithium ion conductivity comparable to that of a liquid electrolyte.

[0004] Research has been ongoing on various solid electrolytes to meet these requirements, and for example, sulfide-based solid electrolytes, oxide-based solid electrolytes, or halide-based solid electrolytes have been proposed.

[0005] Sulfide-based solid electrolytes have the advantage of being more flexible than oxide-based solid electrolytes, making it easier to induce close contact between the solid electrolyte and active material particles, and thus having relatively superior lithium-ion conductivity. However, they have the disadvantage of being less stable when exposed to moisture or oxygen in the air, making the battery manufacturing process difficult. On the other hand, oxide-based solid electrolytes have the disadvantage of being difficult to ensure good contact characteristics between the solid electrolyte and active material, resulting in insufficient ion conductivity.

[0006] In recent years, in order to overcome the shortcomings of the above-mentioned sulfide-based or oxide-based solid electrolytes, halide-based solid electrolytes have been proposed that exhibit excellent stability and a certain level of ionic conductivity.

[0007] Halide-based solid electrolytes mostly have a layered structure, a rock-salt structure, or a structure similar to these. Among them, in particular, various components such as Zr and lanthanum group are substituted or added to the hcp-Li3YCl6-based solid electrolyte, and solid electrolytes with various compositions exist.

[0008] Although such halide-based solid electrolytes are known to exhibit a high level of ionic conductivity by mechanochemical synthesis, the mechanism has not been determined, and it has not reached the level of being able to control the ionic conductivity of halide-based solid electrolytes or freely design halide solid electrolytes with high ionic conductivity.

[0009] Therefore, the development of design rules for composition design of layered halides such as Li3YCl6 compounds is required.

Prior Art Documents

Patent Documents

[0010]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0011] In order to solve the above problems of the prior art, an object of the present invention is to provide a composition design method for optimizing the ionic conductivity of Li3YCl6 compounds.

[0012] Another object of the present invention is to provide a composition design method for optimizing the occupancy rate of metal ions in the layer in Li3YCl6 compounds having a hexagonal close-packed structure.

[0013] Furthermore, the present invention aims to provide a computer-readable recording medium for realizing the aforementioned halide composition design method. [Means for solving the problem]

[0014] To achieve the above technical challenges, the present invention provides a method for designing the composition of a lithium yttrium halide solid electrolyte in a hexagonal close-packed structure, performed by a processor, comprising the steps of: calculating diffusible paths for lithium ions to move to adjacent octahedral sites in the ab-plane of each continuous layer constituting a unit cell of the hexagonal close-packed structure; calculating the active barrier energy for lithium ion diffusion for each of the calculated diffusion paths; and calculating the occupancy rate of yttrium in the unit cell such that a percolation state is formed within the unit cell by the diffusion paths with the lowest calculated active barrier energy.

[0015] In the present invention, the permeation state may include Y-1 ordering, in which the number of yttrium atoms contained in a unit cell according to the standard in the ab-plane is 1, and Y-free ordering, in which the number of yttrium atoms is 0.

[0016] Furthermore, the active barrier energy calculation step may be performed by first-principles calculations-based NEB (Nudged Elastic Band) simulation.

[0017] In the present invention, the diffusion pathway may pass through a tetrahedral site within the unit cell.

[0018] In this case, the diffusion pathway with the low active barrier energy is such that one of the two octahedral sites adjacent to the tetrahedral site is filled with yttrium, and the other is empty. Y T V It may include the route.

[0019] Furthermore, the diffusion pathway with the low activation barrier energy is one in which both octahedral sites adjacent to the tetrahedral site are empty. V T V It may include the route.

[0020] At this time, the T Y T V The route is the aforementioned T V T V It may have an activity barrier energy lower than that of the pathway.

[0021] In the present invention, the occupancy rate calculation step may include the step of calculating the distance between adjacent layers within the unit cell based on the occupancy rate of yttrium, the step of calculating the occupancy rate at which the interlayer distance saturates based on the change in the yttrium occupancy rate, and the step of setting the saturation occupancy rate as the lower limit of the yttrium occupancy rate.

[0022] In this case, the step of calculating the interlayer distance based on the change in yttrium occupancy may be performed by first-principles calculations.

[0023] In the present invention, the occupancy rate calculation step may include a step of setting the maximum value of the yttrium occupancy rate that forms the permeation state as the upper limit of the yttrium occupancy rate.

[0024] Furthermore, the present invention may include a step after the occupancy rate calculation step of calculating the composition of the lithium yttrium halide based on the occupancy rate of yttrium. [Effects of the Invention]

[0025] According to the present invention, it is possible to provide a design method for designing a novel halide composition that optimizes the ionic conductivity of a halide-related Li3YCl6 compound.

[0026] Furthermore, according to the present invention, it is possible to provide a method for designing the composition of a halide in which the occupancy rate of metal ions within the layers is optimized in a hexagonal close-packed Li3YCl6 compound. [Brief explanation of the drawing]

[0027] [Figure 1] (a) is a diagram showing the crystal structure of hcp-Li3YCl6, and (b) is a diagram illustrating possible arrangement models based on the metal arrangement type in the crystal structure of hcp-Li3YCl6. [Figure 2] (a) is a diagram illustrating the ordering of metal ions in each arrangement model, and (b) is a diagram illustrating the diffusion pathway of lithium at each site. [Figure 3] (a) is a graph showing the results of activation barrier calculations based on metal ion arrangement rules, and (b) to (d) are diagrams illustrating the differences in ion conduction pathways based on metal ion arrangement rules. [Figure 4] This is a diagram illustrating the design rules for the halide composition according to one embodiment of the present invention. [Figure 5] This diagram illustrates the metal ion occupancy rate of each layer and the ion conduction pathways resulting from that occupancy rate in a hexagonal close-packed halogenated composition. [Figure 6] This graph plots the target composition according to one embodiment of the present invention and the calculated layered occupancy rate within a unit cell of the hexagonal close-packed structure of the target composition. [Figure 7] Figure 6 is a table summarizing the composition and sources of the conventional literature plotted in the previous document. [Figure 8] This graph shows the results of X-ray diffraction analysis of a halide sample produced according to one embodiment of the present invention. [Figure 9]This is a schematic diagram showing an apparatus to which the composition design method can be applied according to one embodiment of the present invention. [Modes for carrying out the invention]

[0028] Please note that the following description will only explain the parts necessary to understand the embodiments of the present invention, and explanations of other parts may be omitted in order to avoid obscuring the essence of the invention.

[0029] The terms and words used in this specification and in the claims described below should not be interpreted in a manner limited to their ordinary or lexicographical meanings, but rather in a manner consistent with the technical idea of ​​the present invention, based on the principle that inventors may appropriately define the concepts of terms in order to best describe their own invention. Accordingly, the embodiments and configurations shown in the drawings described herein are merely preferred embodiments of the present invention and do not represent the entire technical idea of ​​the present invention, and it should be understood that there may be various equivalents and modifications available at the time of filing.

[0030] Compounds defined by reference to their constituent elements in the specification described later may include compounds containing elements that substitute for or are added to some of the elements mentioned. In this specification, when referring to a compound name by its constituent elements, for example, lithium yttrium chloride (LYC) does not mean only three-component compounds composed of lithium, yttrium, and chlorine, but also includes four-component or more compounds that contain one or more other elements that substitute for some of the metal ions, or that further contain other intersitial elements in the crystal structure.

[0031] The following details the design procedure for layered halide solid electrolytes, such as LYC compounds, and their compositions, with reference to the drawings.

[0032] ≪Crystal structure of A.hcp-Li3YCl6≫

[0033] (a) of FIG. 1 shows the crystal structure of hcp-Li3YCl6 (in this specification, hcp-Li3YCl6 and compounds based on this structure are collectively referred to as hcp-LYC), and (b) of FIG. 1 shows two arrangement models possible depending on the metal arrangement type in the hcp-LYC structure, namely, the ααα model and the αββ model.

[0034] Referring to (a) of FIG. 1, in the exemplary structure of hcp-LYC, two layers, layer 1 and layer 2, are arranged continuously, but in each layer, Cl - Halogen ions such as Cl ions form a hexagonal closed packed structure, and lithium ions and metal ions are ordered in the octahedral sites formed by the halogen ions.

[0035] As shown in (a) of FIG. 1, there are a total of two sites where metal ions can enter each layer. One site is the 1a site located at the vertex based on the unit cell, and the other site is the 2d site located in the center of each layer.

[0036] ≪B. Layer Structure and Lithium Diffusion Path Modeling of hcp-LYC≫

[0037] In order to understand the tendency of ion conductivity change due to the number and arrangement of metals, two models can be set depending on the position of metal ions in the 2d site. One is a model including the ααα layer in which metal ions coexist in the 2d site and the 1a site, as shown in (b) of FIG. 1, and the other is a model including the αββ layer in which ions are divided into layers in the 2d site and the 1a site, as shown in (c) of FIG. 1. The latter structure may be the most stable arrangement in the hcp-LYC structure.

[0038] For both models, ionic conductivity calculations for the overall structure and ab-plane / c-axis conductivity calculations were performed, and the results are shown in Figure 1(d). Ionic conductivity was calculated using AIMD (ab initio molecular dynamics) simulation, and VASP (Vienna ab-initio Simulation Package) was used as the software.

[0039] Referring to Figure 1(d), it can be confirmed that the conductivity of the αββ model has a higher value.

[0040] A noteworthy point is that, in the ααα model, despite the c-axis diffusion rate being faster than in the αββ model, the diffusion rate in the ab-plane is lower than in the αββ model, resulting in a lower overall ionic conductivity. This suggests that ab-plane diffusion determines the overall ionic conductivity in this structure. Therefore, it is necessary to explain the influence of the metal arrangement on diffusion in the ab-plane.

[0041] Figure 2(a) illustrates the ordering of metal ions in each model. As shown in Figure 2(a), Y-free ordering and Y-3 ordering are possible in the ααα model, and Y-1 ordering and Y-2 ordering are possible in the αββ model. Here, the number following Y represents the number of metal atoms present in the ab-plane according to the unit cell standard.

[0042] By separating the layers of each model individually and examining the sites where Li can exist in the ab-plane, it can be seen that in the case of Y-free ordering, where there are no metal ions at all, and Y-1 ordering, where the total number of metal ions is 1, an environment can be created in which Li can percolate overall. In the case of Y-2 ordering and Y-3 ordering, it can be seen that Li is isolated between metal ions, creating an environment in which ion diffusion is unlikely to occur.

[0043] Figure 2(b) is a diagram illustrating the diffusion pathway of lithium at each site.

[0044] Referring to Figure 2(b), it can be seen that for lithium ions to move, they must pass through an intermediate tetrahedral site that is face-shared with an octahedral site that can be occupied by the metal. In this case, the diffusion pathway when the metal ion is at the octahedral site is T Y Let T be the diffusion path when the octahedral site is empty. V If so, T Y In this case, the repulsive force of the metal ions is strong, creating an environment where lithium ions have difficulty passing through, whereas in T, where there are no metal ions... V In this case, it can be understood that the environment is conducive to lithium ions passing through the tetrahedral sites.

[0045] As described later, the present invention calculates various physical quantities based on first-principles calculations using quantum chemistry. In the present invention, ionic conductivity, hopping rate, active barrier energy, interlayer spacing, lithium probability density, and energy of specific sites are just a few examples of the physical quantities that can be calculated.

[0046] ≪Calculation of Active Barrier Energy via Diffusion Pathway of Lithium C≫

[0047] The active barrier energy required for lithium ions to pass through tetrahedral sites was calculated based on whether or not metal ions occupy octahedral sites. In this invention, the active barrier energy may be calculated based on first-principles calculations.

[0048] In this invention, first-principles molecular dynamics (AIMD) and NEB (nudged elastic band) methods may be used to calculate the active barrier energy.

[0049] First-principles calculations are methods for solving the Schrödinger equation, which describes the state of matter based on quantum chemistry. They do not use other empirical quantities, but instead calculate the properties of matter by considering fundamental constants of matter such as Planck's constant and the mass of electrons, as well as the interactions between nuclei and electrons within atoms and between electrons themselves. Because they do not use empirical quantities, they are also called ab-initio calculations.

[0050] This invention uses first-principles molecular dynamics (ab-initio molecular dynamics, AIMD) to observe the movement behavior of lithium ions at a set temperature, thereby enabling the measurement of lithium ion conductivity and the number of lithium hopping cycles. In particular, by finding the most stable state during lithium movement, the lithium diffusion pathway and the activation energy required to pass through that pathway can be calculated. In this case, the Nudged Elastic Band (NEB) simulation method may be used to analyze the lithium diffusion characteristics.

[0051] The present invention may be implemented in conjunction with commercial software for first-principles calculations. For example, the present invention can, of course, utilize software modules including AIMD and NEB for first-principles calculations using VASP (Vienna ab-initio Simulation Package).

[0052] The active barrier energy was calculated using NEB simulation with the commercial software VASP, and the hopping rate in the AIMD simulation results was analyzed using a MATLAB program.

[0053] Figures 2(d) and (e) are graphs showing the simulation results. Referring to the same figure, when metal ions are present in both lithium transport paths (i.e., T Y T YIn this case, the energy required for passage is very high, making it difficult for lithium to move, and thus it exhibits a low hopping rate. Also, when metal ions are present on only one side (i.e., T V T Y ) has high energy T Y Instead, a lower energy T V It was found that lithium ions can move through this pathway. Furthermore, it was confirmed that lithium ions can pass through both pathways completely when there are no metal ions present in either pathway.

[0054] Uniquely, or rather, the lithium pathway has absolutely no metal ions. V T V In contrast, T, which has one metal ion V T Y or T Y T V In this case, it can be seen that the diffusion of lithium ions is faster. This phenomenon can be explained as follows.

[0055] Comparing a Y-free ordering layer, which contains no metal ions at all, with a Y-1 ordering layer, which contains one metal ion, the biggest difference in lithium conduction is that the cross-sectional area of ​​the most important path in planar diffusion (i.e., the interlayer distance) differs depending on the number of metal ions.

[0056] To investigate the effect of interlayer distance on diffusion, T v T v The activation barrier was calculated by arbitrarily changing the interlayer distance in each case. The activation barrier was calculated using Nudged Elastic Band (NEB) simulation, and VASP was used as the software.

[0057] Figure 3(a) is T v T vThis graph shows the activation barrier calculation results. Regardless of the presence or absence of metal ions in the layer, T depends on the interlayer distance. v T v It can be confirmed that the activity barrier changes uniformly. Furthermore, it can be confirmed that the activity barrier in diffusion decreases as the interlayer distance increases.

[0058] ≪The effect of D. yttrium occupancy on interlayer spacing≫

[0059] On the other hand, the results of calculating the effect of the Y occupancy rate on the inter-story spacing are shown in Figure 3(d). This inter-story spacing was calculated by analyzing the results of first-principles calculations. VASP was used as the software.

[0060] Referring to Figure 3(d), it was found that saturation occurs after the occupancy of Y increases to 0.166.

[0061] In other words, it was found that the change in the degree of diffusion between Y-free ordering and Y-1 ordering, which do not contain metal ions, is due to this difference in interlayer distance, and that when there are 0.166 or more metal ions, the lithium ion pathway is broadened to some extent.

[0062] Furthermore, as shown in Figure 3(c), it can be calculated that distortion occurs at the intermediate site when Y is present in the lithium diffusion path, and it can be seen that the elongation of such tetrahedral sites also affects the expansion of the interlayer distance.

[0063] On the other hand, Figure 3(b) shows that the distance between adjacent Y ions is significantly shorter in the Y-1 layer (7.19 Å) compared to the Y-free layer (8.83 Å), resulting in a stronger c-axis repulsion component between adjacent plane Y ions, which increases the interlayer space from 5.97 to 6.17 Å.

[0064] ≪E. Calculation of occupancy rate for optimal percolation≫

[0065] As mentioned above, diffusion in the ab-plane can proceed quickly when the environment within the layer allows for percolation of lithium ions and the interlayer distance is sufficiently wide. On the other hand, a small number of metal ions in the layer is favorable for percolation, but the interlayer distance can only be wide enough when there is an appropriate number of metal ions.

[0066] The range that satisfies both of these conditions may be specified in the following way: The occupancy of metal ions in each layer is preferably above a predetermined lower limit to ensure sufficient interlayer distance and below a predetermined upper limit to allow penetration in each layer. Preferably, in the present invention, the lower limit is 0.166 and the upper limit is 0.444.

[0067] In the present invention, the upper limit may be determined as follows:

[0068] Referring to Figure 4(a), when a hexagonal unit cell is set based on metal ions, the conditions for lithium ion penetration to be possible are, that is, all lithium ions in the hexagonal unit cell are T V T Y or T V T V For this state to be achieved, the central metal ion must be empty, and the two metal ions at the vertices of the unit cell must also be empty. Beyond this occupancy rate, lithium ions cannot pass through the unit cell.

[0069] Figure 4(a) illustrates and explains the calculation method for the threshold value of occupancy required for percolating to occur. Within a hexagonal unit cell, there is one central metal ion site and six vertex sites. However, the vertex sites are shared by two adjacent unit cells, so the total number of metal ion sites within one unit cell is three. Therefore, the maximum number of metal ions in a unit cell in the critical state where percolating is possible, where the central metal ion site and the two vertex metal ions of the unit cell are empty, is (4*1 / 3). Thus, the metal ion occupancy can be calculated as ((4*1 / 3) / 3 = 4 / 9 ≈ 0.444).

[0070] Based on these results, we can determine the design rules for conditions that allow lithium penetration.

[0071] As mentioned above, the hcp-LYC structure consists of a contiguous arrangement of two layers. In a composition with a metal-to-anion ratio of 1:6, there are a total of 6 metal ion sites within the two layers, and a total of 3 metal ions present. In a composition with a metal-to-anion ratio of 1:6, it is possible for metal ions to occupy all the metal ion sites in one layer (e.g., Y-3 ordering), and the occupancy rate in this case can be expressed as 1. On the other hand, in this case, all the metal ion sites in the other layer adjacent to it may be empty (e.g., Y-free ordering), and the occupancy rate in this case can be expressed as 0. Therefore, in the hcp-LYC structure, each layer may have an occupancy rate ranging from 0 to 1, and if the occupancy rate of one layer is k, the occupancy rate of the adjacent layer can be expressed as 1-k. That is, the sum of the occupancy rates of two consecutive layers should be 1.

[0072] Figure 5(a) shows the sites of Y ions within a hexagonal unit cell. As shown, there is one Y ion site at the center and six Y ion sites at the vertices.

[0073] In Figure 5(b), CASE I shows the Y ion occupancy rate k based on whether each vertex is occupied or not when the central Y ion site is occupied by a Y ion, while CASE II shows the Y ion occupancy rate k based on whether each vertex is occupied or not when the central Y ion site is empty.

[0074] Figure 5(c) shows the Li infiltration pathway depending on the Y ion occupancy rate k.

[0075] As mentioned earlier, the critical value for the occupancy rate of a single layer that allows ion penetration is 0.444. If one of two adjacent layers has a metal ion occupancy rate of k=0.444, then the occupancy rate of the other adjacent layer, 1-k, must be 0.556 (=1-0.444). In this case, the other layer must become a non-percolating layer because the number of metal ions exceeds the critical value.

[0076] For example, in order for an hcp-LYC solid electrolyte to have high ionic conductivity, the maximum value of the metal ion occupancy within the structure is 0.444. Therefore, the sum of the occupancy rates of two adjacent layers should be designed to be 0.444 * 2 = 0.888 or less.

[0077] ≪F.hcp-LYC composition design≫

[0078] Based on these findings, the inventors of the present invention have designed a composition that maintains a total metal occupancy of 0.888 or less across two consecutive layers, while also achieving high ionic conductivity without fluctuations in the number of Li atoms within a unit cell.

[0079] In other words, the present invention provides an hcp-LYC-based solid electrolyte composition in which the number of metal ions contained is reduced, the metal ion occupancy rate of individual layers is 0.444 or less, and the sum of the metal ion occupancy rates of the two layers is 0.888 or less.

[0080] Figure 6 is a graph plotting the occupancy rates of layer 1 and layer 2 within a unit cell for the target composition of the present invention and compositions reported in the prior art. Referring to Figure 6, it can be seen that in the case of the conventional composition, the metal composition content is relatively high and is located outside the target region of the present invention. In the formula in Figure 6, Li a M x Cl b In this context, M represents a trivalent or tetravalent ion such as Y, Ho, Er, or Zr that forms an hcp-trigonal structure.

[0081] Figure 7 is a table summarizing the composition and sources of the conventional literature plotted in Figure 6.

[0082] The composition of the present invention can be expressed by the following compositional formula.

[0083] (compositional formula 1) Li3(Y 1-(4-4x) A 3-3x )Cl6(A is a tetravalent cation, and x = 0.75 to 0.888.)

[0084] In the present invention, A comprises at least one element selected from the group consisting of Ti, Zr, Hf, and Rf.

[0085] In this invention, the range of x values ​​may be calculated as follows.

[0086] Here, 1-(4-4x) can be reduced to 4x-3, but 4x-3≧0 must be satisfied, so x≧0.75. On the other hand, in composition formula 1, the number of atoms, 4x-3+3-3x, becomes x, and x is limited to twice the percolation threshold of each layer, which is 0.167~0.444, with a minimum of 0.333 and a maximum of 0.888. Therefore, the value of x that satisfies both of these conditions is 0.75≦x≦0.888, and the preferred LYC composition in the present invention may be optimized within the range of the above-mentioned x value.

[0087] As shown in chemical formula 1, trivalent ions are converted into higher tetravalent ions (A 4+ The empirical formula that reflects the vacancies created by replacing ) is as follows:

[0088] (compositional formula 2) Li3(Y 1-(4-4x) A 3-3x □ (1-x)) Cl6 (where □ represents a void, and x = 0.75 to 0.888.)

[0089] On the other hand, if we consider the case where, in accordance with the number of substituted tetravalent ions, a vacancy is formed corresponding to some of the substituted ions, and the number of lithium ions is reduced corresponding to other parts, thereby maintaining charge balance, the compositional formula of the present invention may be expressed more generally as follows:

[0090] (compositional formula 3) Li 3-a (Y 1-(4-4x) A 3-3x+(a / 4) )Cl6(A is a tetravalent cation, and x = 0.75 ~ (0.888 - a / 4), a = 0 ~ 0.552)

[0091] The compositional formula reflecting the generated vacancies is as follows:

[0092] (compositional formula 4) Li 3-a (Y 1-(4-4x) A 3-3x+(a / 4) □(1-x))Cl6(A is a tetravalent cation, and x=0.75~(0.888-a / 4), a=0~0.552)

[0093] In compositional formulas 3 and 4, if we set a, which represents the decrease in lithium ions, to 0, the formulas become identical to compositional formulas 1 and 2.

[0094] The following describes some experimental examples of solid electrolyte compositions selected according to the aforementioned compositional formula of the present invention.

[0095] <Experimental Example 1>

[0096] To obtain the compositions with the compositional formulas shown in Table 1 below, LiCl, YCl3, and ZrCl4 were weighed according to the molar ratios of Li, Y, Zr, and Cl in the compositional formulas, and then the compositions were synthesized by a mechanochemical synthesis method using a ball mill. In this synthesis, the mechanochemical synthesis conditions were as follows: using a Fritsch Pulverisette 7PL equipped mill at 800-900 rpm, a ball-to-powder ratio of 25:1, 10g of 10mm ZrO2 balls, and 15g of 5mm ZrO2 balls. Each step consisted of 15 minutes of milling followed by a 5-minute rest, for a total of 12 steps and 4 hours of synthesis.

[0097] The compositional formula for this experimental example is shown in Figure 6, Li a M x Cl b This corresponds to the region where x, which indicates the molar ratio of metal ions (M) in the expressed empirical formula, is between 0.8 and 0.888.

[0098] To measure the ionic conductivity of the synthesized composition, a symmetric cell with a SUS / solid electrolyte / SUS structure was used to prevent electrodeposition and desorption of ions within the electrolyte. The solid electrolyte was compressed to 254 MPa and pelletized, and AC impedance measurements were performed at frequencies from 3 MHz to 100 mHz using Biologic's VMP3 under a pressurized state of 75 MPa.

[0099] Table 1 shows the ionic conductivity for each composition.

[0100] [Table 1]

[0101] Figure 8 is a graph showing the X-ray diffraction analysis results for sample #3. For comparison, the XRD data for Li3YCl6 (i.e., x=1) is also shown. From Figure 8, it can be confirmed that sample #3 has the same structure as the comparative example Li3YCl6. Also, Zr 4+The diffraction pattern shifted to the right due to the presence of Zr, which has a small ionic radius and induces the formation of vacancies. 4+ This result shows that the lattice constant decreased due to the addition of [the compound].

[0102] <Experimental Example 2>

[0103] To obtain the composition having the compositional formula shown in Table 2 below, the starting materials were weighed according to the molar ratios of Li, Y, Zr, and Cl in the compositional formula, and then the composition was synthesized. The compositional formula of this experimental example is shown in Figure 6 as Li a M x Cl b This corresponds to the region where x, which represents the molar ratio of metal ions (M) in the expressed composition formula, is 0.9 or greater.

[0104] The ionic conductivity of the synthesized composition was measured and is shown in Table 2.

[0105] [Table 2]

[0106] <Experimental Example 3>

[0107] To obtain a composition satisfying the compositional formula in Table 3, where the ratio of metal ions is 0.8, the starting materials were weighed according to the molar ratios of Li, Y, Zr, and Cl in the compositional formula, and then the composition was synthesized. The a value for compositional formula 3 was calculated and is shown in Table 3.

[0108] The ionic conductivity of the synthesized composition was measured and is shown in Table 3.

[0109] [Table 3]

[0110] <Experimental Example 4>

[0111] To obtain a composition satisfying the compositional formula in Table 4, where the ratio of metal ions is 0.85, the starting materials were weighed according to the molar ratios of Li, Y, Zr, and Cl in the compositional formula, and then the composition was synthesized. The a value for compositional formula 3 was calculated and is shown in Table 4.

[0112] The ionic conductivity of the synthesized compositions was measured and is shown in Table 4.

[0113] [Table 4]

[0114] <Experimental Example 5>

[0115] To obtain a composition satisfying the compositional formula in Table 5, where the ratio of metal ions is 0.88, the starting materials were weighed according to the molar ratios of Li, Y, Zr, and Cl in the compositional formula, and then the composition was synthesized.

[0116] The ionic conductivity of the synthesized composition was measured and is shown in Table 5.

[0117] [Table 5]

[0118] <G. Apparatus to which the design method of the present invention can be applied>

[0119] Figure 9 illustrates an example of a device 100 to which the composition design method of the present invention can be applied. The device 100 may be configured to process data and information according to the composition design method of the present invention. The device 100 may be a user device, but is not limited thereto, and may be a server device that provides composition design services. For example, the device 100 to which the method of the present invention can be applied may include computer devices such as desktop computers and workstations, mobile terminals such as smartphones, and portable devices such as laptop computers. As another example, the device 100 to which the present invention can be applied may be included as part of an ASIC (Application Specific Integrated Circuit) embodied in the form of a SoC (System On Chip).

[0120] Memory 104 can store programs for processing and controlling processor 102, and can store data and information used in the present invention, control information necessary for processing data and information according to the present invention, temporary data generated during the processing of data and information, etc. Memory 104 may be implemented as a storage device such as ROM (Read Only Memory), RAM (Random Access Memory), EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), flash memory, SRAM (Static RAM), HDD (Hard Disk Drive), SSD (Solid State Drive), etc.

[0121] The processor 102 controls the operation of each module in the device 100. In particular, the processor 102 can perform various control functions for carrying out the proposed method of the present invention. The processor 102 may be called a controller, microcontroller, microprocessor, microcomputer, etc. The proposed method of the present invention may be embodied by hardware, firmware, software, or a combination thereof. When the present invention is embodied using hardware, the processor 102 may be equipped with an ASIC (application specific integrated circuit), or a DSP (digital signal processor), DSPD (digital signal processing device), PLD (programmable logic device), FPGA (field programmable gate array), etc., configured to carry out the present invention. On the other hand, when the proposed method of the present invention is implemented using firmware or software, the firmware or software may include instructions related to modules, procedures, or functions that perform the necessary functions or operations for implementing the method of the present invention. These instructions may be stored in memory 104 or in a computer-readable storage medium (not shown) separately from memory 104, and the device 100 may be configured to implement the method of the present invention when executed by the processor 102.

[0122] Furthermore, the device 100 may include a network interface module (NIM) 106. The network interface module 106 is operatively connected to the processor 102, and the processor 102 controls the network interface module 106 to transmit or receive wireless / wired signals that carry information and / or data, signals, messages, etc., over a wireless / wired network. The network interface module 106 supports various communication standards, such as IEEE 802 series, 3GPP LTE(-A), and 3GPP 5G, and can transmit and receive control information and / or data signals according to the applicable communication standard. The network interface module 106 may be implemented outside the device 100 if necessary.

[0123] The embodiments described above combine the components and features of the present invention in a predetermined form. Each component or feature should be considered optional unless otherwise explicitly mentioned. Each component or feature may be implemented in a form that does not combine with other components or features. It is also possible to combine some components and / or features to constitute embodiments of the present invention. The order of operations described in the embodiments of the present invention may be changed. Some components or features of one embodiment may be included in other embodiments, or replaced with corresponding components or features of other embodiments. It is obvious that claims that do not have an explicit reference relationship in the claims may be combined to constitute embodiments, or may be included as new claims by amendment after filing.

[0124] On the other hand, the embodiments disclosed herein and in the drawings are provided only as examples to aid understanding and are not intended to limit the scope of the present invention. It will be apparent to those ordinary skill in the art to which the present invention pertains that other modifications based on the technical idea of ​​the present invention are also possible, in addition to the embodiments disclosed herein.

Claims

1. A method for designing the composition of a hexagonal close-packed lithium yttrium halide solid electrolyte performed by a processor, The steps include calculating the diffusible paths for lithium ions to move to adjacent octahedral sites in the ab-plane of each continuous layer constituting the unit cell of a hexagonal close-packed structure, The steps include: calculating the active barrier energy for lithium ion diffusion for each of the aforementioned calculated diffusion pathways; The step includes calculating the occupancy rate of yttrium within the unit cell such that a percolation state is formed within the unit cell by a diffusion pathway with a low calculated active barrier energy. A method for designing the composition of lithium yttrium halide solid electrolytes.

2. The aforementioned penetration state is A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1, comprising a Y-1 ordering in which the number of yttrium atoms contained in a unit cell according to the standard criteria in the ab plane is 1, and a Y-free ordering in which the number of yttrium atoms is 0.

3. The aforementioned active barrier energy calculation step is performed by first-principles calculations-based Nudged Elastic Band (NEB) simulation. A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1.

4. The diffusion pathway passes through the tetrahedral sites within the unit cell. A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1.

5. The diffusion pathway with the low active barrier energy is one of two octahedral sites adjacent to the tetrahedral site, where one is filled with yttrium and the other is empty. Ｙ T Ｖ Including the route, A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 4.

6. The diffusion pathway with the low activation barrier energy is one in which both octahedral sites adjacent to the tetrahedral site are empty. Ｖ T Ｖ Including the route, A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 5.

7. Said T Ｙ T Ｖ The route is the aforementioned T Ｖ T Ｖ It has a lower activation barrier energy compared to the pathway. A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 6.

8. The aforementioned occupancy rate calculation step is, The steps include: calculating the distance between adjacent layers within the unit cell based on the yttrium occupancy rate; The steps include: calculating the occupancy rate at which the interlayer distance saturates based on the change in the occupancy rate of the yttrium; The step of setting the saturation occupancy rate as the lower limit of the yttrium occupancy rate, A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1.

9. The step of calculating the interlayer distance based on the change in yttrium occupancy rate is as follows: This is performed using first-principles calculations simulations. A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 8.

10. The aforementioned occupancy rate calculation step is, This includes the step of setting the maximum value of the yttrium occupancy rate that forms the aforementioned permeation state as the upper limit of the yttrium occupancy rate. A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1.

11. After the occupancy rate calculation step, The step includes calculating the composition of the lithium yttrium halide based on the yttrium occupancy rate, A method for designing the composition of a lithium yttrium halide solid electrolyte according to claim 1.

12. A computer-readable storage medium storing instructions configured to embody the method described in any one of claims 1 to 11.

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