A method, system, terminal and readable storage medium for obtaining ion migration number in a molten salt system

Abstract

The present invention discloses a method, system, terminal and readable storage medium for obtaining the ion migration number in a molten salt system, the method comprising: constructing a periodic structural model of the molten salt system to be evaluated, and then performing molecular dynamics simulation to obtain the ion motion trajectory and stable ion structure in a stable state; then calculating the displacement matrix and Mulliken charge distribution of each ion; based on the ionic conductivity calculation theory and introducing the correlation coefficient of each ion pair, and using the displacement matrix and Mulliken charge distribution of each ion to obtain the ion migration number in the molten salt system; wherein the ionic conductivity of each ion is corrected using the correlation coefficient. The method of the present invention introduces the correlation coefficient of the ion pair, and the obtained ion migration number is more accurate, and the molecular dynamics simulation is used to calculate the ion migration number in the molten salt system, without the need to design a specific molten salt measuring instrument and high-temperature electrochemical experiments, which can reduce the experimental cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrochemical metallurgy, and specifically relates to a method, system, terminal and readable storage medium for obtaining ion migration numbers in a molten salt system. Background Art

[0002] The ion migration number in the molten salt system can directly describe the relative contribution of a certain ion in the electrolyte to the total charge transfer. It is an important industrial parameter used to clarify the ion migration process and kinetic characteristics in the molten salt. However, due to the limitations of high-temperature electrochemical conditions, experimental measurements of the migration number in the molten salt system are extremely difficult to carry out, and usually require the design of complex corrosion-resistant equipment. In addition, experimental measurements of the molten salt ion migration number are often based on the Hittorf method. From a thermodynamic point of view, this theory considers the system to be an open system and involves strong approximate interpretations, making it difficult to effectively describe the migration characteristics of molten salt ions. The lack of data related to the molten salt ion migration number has seriously hindered the mechanism understanding and energy efficiency optimization of many electrochemical metallurgical processes.

[0003] With the gradual development of computational chemistry, the use of computational simulation methods to study the structure and properties of materials has been increasingly recognized. Molten salt is essentially a highly correlated, non-completely dissociated ion system with strong short-range interactions, and this inter-ionic interaction has an important impact on the ion migration in the melt. For example, experiments on cryolite electrolytes show that the current in molten salt is almost entirely composed of Na + ion carrier, while other ions (such as O 2- 、F - and Al 3+ ) There is obvious migration interference between the two. However, most of the existing molecular simulation studies on molten salt systems directly ignore the ion correlation and can only indirectly judge the ion migration and charge transfer in the melt by calculating the self-diffusion coefficient of the ions. The results obtained are extremely different from the experimental values ​​(more than 30%) and cannot meet the industrial demand for accurately and directly obtaining the molten salt ion migration number.

[0004] Therefore, it is necessary to propose a simple and effective method to calculate the ion migration number in the molten salt system and introduce the ion correlation in the actual melt, so as to provide important theoretical guidance for the optimal design of the molten salt electrolyte system. Summary of the invention

[0005] The purpose of the present invention is to provide a method, system, terminal and readable storage medium for obtaining the ion migration number in a molten salt system in view of the problem that the calculation of the ion migration number in the molten salt system in the prior art is inaccurate and the accuracy needs to be improved. The method uses molecular dynamics simulation to calculate the ion migration number in the molten salt system for the molten salt system to be evaluated, without the need to design a specific molten salt measuring instrument or to conduct a high-temperature electrochemical experiment; in particular, the present invention takes into account the correlation coefficient of ion pairs and provides a more reliable and accurate means of calculating the ion migration number.

[0006] On the one hand, the present invention provides a method for obtaining an ion migration number in a molten salt system, which comprises the following steps:

[0007] Step 1: construct a periodic structure model for the molten salt system to be evaluated, and perform molecular dynamics simulation based on the periodic structure model to obtain the ion motion trajectory and stable ion structure in a stable state;

[0008] Step 2: Obtaining the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and stable ion structure;

[0009] Step 3: Introduce the correlation coefficient of each ion pair, and use the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system; wherein the correlation coefficient is used to correct the ionic conductivity of each ion.

[0010] The present invention calculates the ion migration number in the molten salt system by molecular dynamics simulation, and does not need to design a specific molten salt measuring instrument or conduct high-temperature electrochemical experiments. It can replace traditional experimental measurement methods, and the calculation method is simple, efficient, low-cost, and has strong practical value. At the same time, the correlation coefficient of the ion pair is introduced to correct the ionic conductivity of the ion, and the ion migration number under complete dissolution is the ratio of the ionic conductivity of each ion to the total ionic conductivity, so the introduction of the correlation coefficient of the ion pair can effectively correct the ion migration number of the ion, and obtain the ion migration number of each ion under incomplete dissolution, which is more compatible with the actual problem, and the obtained ion migration number is more accurate.

[0011] Optionally, the correlation coefficient of each ion pair is divided into a correlation coefficient of the same type of ion pairs and a correlation coefficient of different types of ion pairs.

[0012] Optionally, the calculation formula of the ion migration number that introduces the correlation coefficient of each ion pair is as follows:

[0013]

[0014] in, is the ion migration number of ion i in the molten salt system, is the correlation coefficient of the same ion pair ii, which means that in the same ion pair ii, ion i is affected by the migration correlation of the same ion i; is the correlation coefficient of heterogeneous ion pair ij, which means that in heterogeneous ion pair ij, ion i is affected by the migration correlation of heterogeneous ion j, and always satisfies Z i , Z j are the Mulliken charges of ion i and ion j, Δ i (t), Δ j (t) represent the displacement of ion i and ion j at time t respectively.

[0015] The present invention studies the correlation coefficient of the same ion pair ii and the correlation coefficient of the different ion pairs ij, and takes the ion correlation into account more comprehensively, overcoming the problem that most of the existing molecular simulation studies on molten salt systems directly ignore the ion correlation and can only indirectly judge the ion migration and charge transfer in the melt by calculating the self-diffusion coefficient of the ions. The obtained results deviate greatly from the experimental values ​​(more than 30%), and cannot meet the industrial demand for accurately and directly obtaining the molten salt ion migration number.

[0016] Optionally, the correlation coefficient of heterogeneous ion pairs is determined as follows:

[0017] For heterogeneous ion pairs, heteroelectric ions with short-range interactions are combined into a first proximity coupling sequence, and homoelectric ions with short-range interactions are combined into a second proximity coupling sequence;

[0018] Then, the correlation coefficients of the heterogeneous ion pairs are calculated using a pair approximation algorithm and a quadruple approximation algorithm for the first proximity coupling sequence and the second proximity coupling sequence, respectively.

[0019] Optionally, for the first proximity coupling sequence, when the correlation coefficient of the heterogeneous ion pairs is calculated using a pair approximation algorithm, the process is as follows:

[0020] For complex cation m and any anion k, the correlation coefficient satisfies

[0021] For a free cation n and any anion k, the correlation coefficient satisfies

[0022] Optionally, for the second proximity coupling sequence, the process of calculating the correlation coefficient of the heterogeneous ion pairs using the quadruple approximation algorithm is as follows:

[0023] (i) Determine the main anion / cation species and their existence forms in the periodic structure model in step 1;

[0024] (ii) constructing several quadruple models consisting of two main cations and two main anions, and satisfying that the total ion mole fraction of the quadruple is greater than a specific value L, which is set according to the complex characteristics of the molten salt system under study, but is generally not less than 0.7;

[0025] (iii) Calculate the cage autocorrelation function of each quadruple, and derive the correlation coefficient between the second neighboring ions based on the ratio of the molar viscosity activation energy of each quadruple; the formula satisfies:

[0026] E1:E2:E3...E n =ω1:ω2:ω3...ω n

[0027] Among them, E i is the molar viscosity activation energy of the ith quartet, n is the number of quartets, ω i is the correlation coefficient between ions on the i-th quadruplex.

[0028] Optionally, the correlation coefficient for the same type of ion pairs is calculated based on the load-charge ratio of the same type of ions in the stable molten salt configuration. In the present invention, it is preferably simplified and set to 1.

[0029] Optionally, the generation process of the first proximity coupling sequence and the second proximity coupling sequence is as follows:

[0030] If the side length of the periodic model of the molten salt system is smaller than The simulation system is enlarged N*N*N times in the three-dimensional coordinate system, and the coordinate matrix of the ions in the entire system after the enlargement is extracted; otherwise, the three-dimensional space coordinate matrix of the ions in the periodic model is directly extracted, and N is a positive integer;

[0031] Calculate the radial distribution function of different ion pairs, and then determine the surrounding ion distribution according to the peak position in the radial distribution function curve; if the first peak position exceeds It is determined that there is no short-range interaction between the ion pairs;

[0032] Finally, the ions with the same charge that have short-range interaction are combined into a first proximity coupling sequence, and the ions with different charges that have short-range interaction are combined into a second proximity coupling sequence.

[0033] In a second aspect, the present invention provides a system based on the above-mentioned ion migration number acquisition method, comprising:

[0034] A periodic structure model building module is used to build a periodic structure model for the molten salt system to be evaluated;

[0035] A dynamic simulation module, which performs molecular dynamics simulation based on the periodic structure model to obtain ion motion trajectories and stable ion structures in a stable state;

[0036] A parameter acquisition module, which acquires the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0037] The calculation module is used to introduce the correlation coefficient of each ion pair, and calculate the ion migration number in the molten salt system using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient.

[0038] In a third aspect, the present invention provides a terminal, comprising a processor and a memory, wherein the memory stores a computer program, and the processor calls the computer program to implement:

[0039] Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation;

[0040] Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0041] Introducing the correlation coefficient of each ion pair, and using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system;

[0042] Among them, molecular dynamics simulation is carried out based on the periodic structure model of the molten salt system to be evaluated.

[0043] In a fourth aspect, the present invention provides a readable storage medium storing a computer program, wherein the computer program is called by a processor to implement:

[0044] Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation;

[0045] Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0046] Introducing the correlation coefficient of each ion pair, and using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system;

[0047] Among them, molecular dynamics simulation is carried out based on the periodic structure model of the molten salt system to be evaluated.

[0048] Beneficial Effects

[0049] 1. The present invention provides a method for obtaining the ion migration number in a molten salt system, which calculates the ion migration number in the molten salt system by molecular dynamics simulation, without the need to design a specific molten salt measuring instrument, without the need to conduct high-temperature electrochemical experiments, and can replace traditional experimental measurement methods. The calculation method is simple, efficient, and low-cost, and has strong practical value. In addition to basic physicochemical data such as density, melting point, and chemical composition, the present invention does not require any complex experiments to provide data support, and the final ion migration number result can be obtained completely based on quantum chemical calculations, which can greatly reduce the experimental cost and shorten the research and development cycle of new molten salt electrolytes.

[0050] 2. In a further preferred embodiment of the present invention, the present invention studies the correlation coefficients of the same ion pairs ii and the correlation coefficients of the different ion pairs ij, and considers the ion correlation more comprehensively, overcoming the problem that most of the existing molecular simulation studies of molten salt systems directly ignore the ion correlation. In particular, for the combination of ions with the same charge, the strong short-range interaction between ions in the molten salt is divided into two types of proximity couplings, which can effectively describe the interference effect of ion migration and achieve higher calculation accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a technical idea flow chart of a method for obtaining ion migration number in a molten salt system provided by the present invention;

[0052] Figure 2 It is a unit cell model diagram of the [KF-NaF-AlF3]-Al2O3 molten salt system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0053] The present invention provides a method for obtaining an ion migration number in a molten salt system, which is used to obtain an ion migration number in a molten salt system. The present invention will be further described below in conjunction with an embodiment, wherein this embodiment is described by taking the [KF-NaF-AlF3]-Al2O3 molten salt system in the aluminum electrolysis industry as an example, and it should be understood that the present invention is not limited to this application.

[0054] Embodiment 1:

[0055] This embodiment provides a method for obtaining an ion migration number in a molten salt system, which comprises the following steps:

[0056] Step 1: Construct a periodic structural model for the molten salt system to be evaluated, and perform molecular dynamics simulation based on the periodic structural model to obtain the ion motion trajectory and stable ion structure in a stable state.

[0057] In this embodiment, the [KF-NaF-AlF3]-Al2O3 aluminum electrolyte molten salt is used, according to its molecular ratio of 1.3, aluminum oxide concentration of 6%, and density of 1.87 g / cm 2 And the physicochemical characteristics of the melting point of 960℃, establish Figure 2 The unit cell model (periodic structure model) shown contains 202 atoms and its model size is Then, a first-principles molecular dynamics simulation of up to 15 ps was performed in Material Studio, and the last 5000 frames were extracted to obtain the ion motion trajectory and stable ion structure.

[0058] Step 2: Obtain the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and stable ion structure.

[0059] Step 3: Introduce the correlation coefficient of each ion pair, and use the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system.

[0060] In this embodiment, the Green-Kubo linear response equation is used to obtain the ionic conductivity of the molten salt system, as follows:

[0061] For the total ionic conductivity σ:

[0062]

[0063] Where β is equal to 1 / k B T(k B is the Boltzmann constant), V is the equilibrium volume of the simulation unit cell, and Z i is the Mulliken charge of ion i, Δ i (t) represents the displacement of ion i at time t. i σ i , decomposing the total ionic conductivity into the contribution of individual ions, i.e., the partial ionic conductivity σ of ion i i for:

[0064]

[0065] In this example, the total ionic conductivity of the molten salt system is 186.95 S / m, where the ionic conductivities of various ions are Na + Ion (47.98S / m), K + Ion (29.04S / m), Al 3+ Ion (46.09S / m), F - ions (17.75S / m) and O 2-ions (46.09S / m).

[0066] Furthermore, the ion migration number of the ideal molten salt [KF-NaF-AlF3]-Al2O3 in the completely dissociated state is equal to the ratio of the partial ion conductivity of each type of ion to the total ion conductivity, and the formula is as follows:

[0067]

[0068] Among them, t i ful. is the ion migration number of ion i in the completely dissociated state, Z i , Z j are the Mulliken charges of ion i and ion j, Δ i (t), Δ j (t) represent the displacement of ion i and ion j at time t respectively.

[0069] For example, in the ideal molten salt [KF-NaF-AlF3]-Al2O3 in the completely dissociated state, the ion migration number is: Na + Ion (0.21), K + Ion (0.15), Al 3+ Ion (0.32), F - ions (0.09) and O 2- ions (0.23). It can be seen that this traditional method infers that Al 3+ ions are the main conductive ions in electrolyte molten salts, which obviously violates the observation laws in the experiment, which further shows that it is crucial to consider ion correlation.

[0070] Furthermore, the present invention introduces the correlation coefficient to correct the ionic conductivity of each ion, that is, introduces the correlation coefficient matrix ω of each ion pair to correct the coupling interference effect of ion migration in the melt. Specifically, the ion migration number of the non-completely dissociated molten salt system (actual molten salt) is calculated according to the following formula:

[0071]

[0072] in, Describe that in ion pair ii, ion i is affected by the migration correlation from similar ion i; Indicates that in ion pair ij, ion i is affected by the migration correlation of heterogeneous ion j, and always satisfies

[0073] The above ion migration number can be decomposed into: the autocorrelation effect between the same ions and the cross-correlation effect between different ions, and the decomposition form is as follows:

[0074]

[0075] in, represents the contribution of the autocorrelation effect of the same ion to the migration number of ion i, represents the cross-correlation contribution from the species ions, Z i is the Mulliken charge of ion i, Δ i (t) represents the displacement of ion i at time t.

[0076] Therefore, in order to calculate the correlation coefficient matrix, the correlation coefficients for the same ion pairs are In this embodiment, the Mulliken charge difference of the same type of ions obtained in the stable configuration is less than 10%, so it is directly simplified and set to 1. In other feasible embodiments, it can be calculated based on the load charge ratio of the same type of ions in the stable molten salt configuration.

[0077] Correlation coefficients for heterogeneous ion pairs It is decomposed into the first proximity coupling effect and the second proximity coupling effect, and the correlation coefficients of heterogeneous ion pairs are calculated using the pair approximation algorithm and the quadruple approximation algorithm respectively.

[0078] The process of decomposing the cross-correlation effect of heterogeneous ion pairs into the first proximity coupling effect and the second proximity coupling effect is as follows:

[0079] (i) If the side length of the periodic model of the molten salt system is smaller than The simulation system is enlarged N*N*N times in a three-dimensional coordinate system, and the coordinate matrix of the ions in the entire system after the enlargement is extracted; otherwise, the three-dimensional space coordinate matrix of the ions in the periodic model is directly extracted;

[0080] (ii) Calculate the radial distribution function of different ion pairs, and then determine the surrounding ion distribution according to the peak position in the curve; if the first peak position exceeds It is determined that there is no short-range interaction between the ion pairs;

[0081] (iii) Finally, the heteroelectric ions that have short-range interactions are combined into a first proximity coupling sequence (i.e., cation-anion), and the homoelectric ions that have short-range interactions are combined into a second proximity coupling sequence (i.e., cation-cation and anion-anion).

[0082] Among them, for the first proximity coupling effect, the correlation coefficient ω between heterogeneous ions is calculated i-j The specific execution process is as follows:

[0083] (i) For the complex cation m and any anion k, the correlation coefficient satisfies

[0084] (ii) For a free cation n and any anion k, the correlation coefficient satisfies

[0085] For the second proximity coupling effect, calculate the correlation coefficient ω between heterogeneous ions i-j The specific execution process is as follows:

[0086] (i) determining the main anion / cation species and their existence forms of the stable configuration in step 1;

[0087] (ii) constructing several quadruple models consisting of two main cations and two main anions, and satisfying that the total ion mole fraction of the quadruple is greater than a specific value L, which is set according to the complex characteristics of the molten salt system under study, but is generally not less than 0.7;

[0088] (iii) Calculating the cage autocorrelation function of each quadruple, and deriving the correlation coefficient between the second neighboring ions based on the ratio of the molar viscosity activation energy of each quadruple obtained.

[0089] After calculating the correlation coefficient, substitute From the formula, the ion migration number of each ion can be calculated.

[0090] This example is based on the actual molten salt [KF-NaF-AlF3]-Al2O3, and the calculation results are as follows:

[0091] (i) For free Na in aluminum electrolyte melt + , K + Cation, with F - and O 2- When anions combine to form ion pairs, their ion migration number will be enhanced by interference from other ions, thus satisfying the following relationship:

[0092]

[0093] (ii) For the complexed Al in the aluminum electrolyte melt 3+ Cations, consisting of Al 3+ 、F - and O 2- The coordination complexes formed by ions can be considered as specific anionic species that offset each other's interference with the migration number, thus satisfying the following relationship:

[0094]

[0095] For the second proximity coupling involving isoelectric ion pairs, the quadruple approximation assumption is used to calculate the correlation coefficient, and the calculation process is as follows:

[0096] (i) The stable ion structures of 200 frames were extracted and statistically analyzed, and it was found that the main cations and anions in the [KF-NaF-AlF3]-Al2O3 molten salt system are Na + , K + , F - and O 2- ,in and Represent the Al in the penta-ligand and hexa-ligand, respectively. 3+ ion;

[0097] (ii) Within the composition and temperature range studied, the molten salt can be considered to contain only the following 11 main quadruplets: NaNaFF, KKFF, NaAl V FF、NaAl VI FF, NaKFF, KAl V FF, KAl VI FF、NaAl VI FO, KAl VI FO、Al VI Al VI OO and Al VI Al VI FF, and construct the relevant quadruple model to characterize the second neighbor ion pair (e.g., NaKFF quadruple is equivalent to Na-FK neighbor ion pair);

[0098] (iii) The cage autocorrelation function of each quadruple was calculated, and the correlation coefficients between the second neighboring ions were derived based on the corresponding molar viscosity activation energy ratios obtained (Table 1).

[0099] Table 1 Correlation coefficients of the main quadruplets and their second nearest neighbor ion pairs in molten salts

[0100]

[0101]

[0102] Finally, the ion migration number in the [KF-NaF-AlF3]-Al2O3 molten salt system was calculated, and the results are shown in Table 2. It can be seen that the simulation results are in good agreement with the experimental data, with a relative error of less than 10%, which fully proves the reliability of the calculation method and can reasonably and effectively describe the actual migration characteristics of ions in the molten salt system.

[0103] Table 2 Calculation results of ion migration numbers in [KF-NaF-AlF3]-Al2O3 molten salt

[0104]

[0105] It should be understood that without departing from the concept of the present invention, the present invention is not limited to the above when using the correlation coefficient to correct the ionic conductivity of each ion. The only implementation method recorded in the formula, the modified examples based on this formula and the modified examples based on the technical concept disclosed in the present invention all belong to the protection scope of the present invention. In addition, based on the introduction of the correlation coefficient disclosed in the present invention, especially the correlation coefficient of the same type ion pair ii and the different type ion pair ij, how to calculate its value, the present invention does not specifically limit the implementation method.

[0106] Embodiment 2:

[0107] This embodiment provides a system based on the above-mentioned ion migration number acquisition method, which includes:

[0108] A periodic structure model building module is used to build a periodic structure model for the molten salt system to be evaluated;

[0109] A dynamic simulation module, which performs molecular dynamics simulation based on the periodic structure model to obtain ion motion trajectories and stable ion structures in a stable state;

[0110] A parameter acquisition module, which acquires the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0111] The calculation module is used to introduce the correlation coefficient of each ion pair, and calculate the ion migration number in the molten salt system using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient.

[0112] It should be understood that the specific implementation process of the above-mentioned unit modules refers to the method content, and the present invention will not be specifically repeated here, and the division of the above-mentioned functional module units is only a division of logical functions. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. At the same time, the above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units.

[0113] Embodiment 3:

[0114] This embodiment provides a terminal, which includes a processor and a memory, wherein the memory stores a computer program, and the processor calls the computer program to implement:

[0115] Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation;

[0116] Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0117] Introducing the correlation coefficient of each ion pair, and using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system;

[0118] Among them, molecular dynamics simulation is carried out based on the periodic structure model of the molten salt system to be evaluated.

[0119] In some feasible ways, the periodic structure model building process and the molecular dynamics simulation process are also implemented on the terminal device, and then the processor calls the computer program to further implement:

[0120] A periodic structural model of the molten salt system to be evaluated is constructed, and molecular dynamics simulation is performed based on the periodic structural model to obtain the ion motion trajectory and stable ion structure in a stable state.

[0121] The terminal also includes: a communication interface for communicating with external equipment and performing data interactive transmission.

[0122] The memory may include a high-speed RAM memory, and may also include a non-volatile memory, such as at least one disk memory.

[0123] If the memory, processor and communication interface are implemented independently, the memory, processor and communication interface can be connected to each other through a bus and communicate with each other. The bus can be an industrial standard architecture bus, a peripheral device interconnection bus or an extended industrial standard architecture bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc.

[0124] Optionally, in a specific implementation, if the memory, processor and communication interface are integrated on a chip, the memory, processor and communication interface can communicate with each other through an internal interface.

[0125] For the specific implementation process of each step, please refer to the description of the above method.

[0126] It should be understood that in the embodiments of the present invention, the processor may be a central processing unit (CPU), and the processor may also be other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The memory may include a read-only memory and a random access memory, and provide instructions and data to the processor. A portion of the memory may also include a non-volatile random access memory. For example, the memory may also store information about the type of device.

[0127] Embodiment 4:

[0128] This embodiment provides a readable storage medium storing a computer program, wherein the computer program is called by a processor to implement:

[0129] Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation;

[0130] Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure;

[0131] Introducing the correlation coefficient of each ion pair, and using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient to calculate the ion migration number in the molten salt system;

[0132] Among them, molecular dynamics simulation is carried out based on the periodic structure model of the molten salt system to be evaluated.

[0133] In some feasible embodiments, the computer program of the periodic structure model construction process and the molecular dynamics simulation process is also stored in the readable storage medium, and then the computer program is called by the processor to further implement:

[0134] A periodic structural model of the molten salt system to be evaluated is constructed, and molecular dynamics simulation is performed based on the periodic structural model to obtain the ion motion trajectory and stable ion structure in a stable state.

[0135] For the specific implementation process of each step, please refer to the description of the above method.

[0136] The readable storage medium is a computer-readable storage medium, which may be an internal storage unit of the controller described in any of the foregoing embodiments, such as a hard disk or memory of the controller. The readable storage medium may also be an external storage device of the controller, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the controller. Furthermore, the readable storage medium may also include both an internal storage unit of the controller and an external storage device. The readable storage medium is used to store the computer program and other programs and data required by the controller. The readable storage medium may also be used to temporarily store data that has been output or is to be output.

[0137] Based on this understanding, the technical solution of the present invention, in essence or in other words, the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned readable storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc., various media that can store program codes.

[0138] It should be emphasized that the examples described in the present invention are illustrative rather than restrictive, and therefore the present invention is not limited to the examples described in the specific embodiments. Any other embodiments derived by those skilled in the art based on the technical solution of the present invention that do not depart from the purpose and scope of the present invention, whether modified or replaced, also fall within the scope of protection of the present invention.

Claims

1. A method for obtaining ion migration number in a molten salt system, characterized in that: The following steps are involved: Step 1: construct a periodic structure model for the molten salt system to be evaluated, and perform molecular dynamics simulation based on the periodic structure model to obtain the ion motion trajectory and stable ion structure in a stable state; Step 2: Obtaining the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and stable ion structure; Step 3: introducing the correlation coefficient of each ion pair, and calculating the ion migration number in the molten salt system using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient; wherein the ionic conductivity of each ion is corrected using the correlation coefficient; The correlation coefficient of each ion pair is divided into the correlation coefficient of the same type of ion pairs and the correlation coefficient of different types of ion pairs; The calculation formula of the ion migration number with the correlation coefficient of each ion pair introduced is as follows: in, is the ion migration number of ion i in the molten salt system, is the correlation coefficient of the same ion pair ii, which means that in the same ion pair ii, ion i is affected by the migration correlation of the same ion i; is the correlation coefficient of heterogeneous ion pair ij, which means that in heterogeneous ion pair ij, ion i is affected by the migration correlation of heterogeneous ion j, and always satisfies Zi and Zj are the Mulliken charges of ion i and ion j, respectively. Δi(t), Δ j (t) represent the displacement of ion i and ion j at time t respectively.

2. The method according to claim 1, characterized in that: The correlation coefficients for heterogeneous ion pairs were determined as follows: For heterogeneous ion pairs, heteroelectric ions with short-range interactions are combined into a first proximity coupling sequence, and homoelectric ions with short-range interactions are combined into a second proximity coupling sequence; Then, the correlation coefficients of the heterogeneous ion pairs are calculated using a pair approximation algorithm and a quadruple approximation algorithm for the first proximity coupling sequence and the second proximity coupling sequence, respectively.

3. The method according to claim 2, characterized in that: For the first proximity coupling sequence, when the correlation coefficient of the heterogeneous ion pairs is calculated using the pair approximation algorithm, the process is as follows: For complex cation m and any anion k, the correlation coefficient satisfies For a free cation n and any anion k, the correlation coefficient satisfies 4. The method according to claim 2, characterized in that: The generation process of the first proximity coupling sequence and the second proximity coupling sequence is as follows: If the side length of the periodic model of the molten salt system is smaller than The simulation system is enlarged N*N*N times in the three-dimensional coordinate system, and the coordinate matrix of the ions in the entire system after the enlargement is extracted; otherwise, the three-dimensional space coordinate matrix of the ions in the periodic model is directly extracted, and N is a positive integer; Calculate the radial distribution function of different ion pairs, and then determine the surrounding ion distribution according to the peak position in the curve; if the first peak position exceeds It is determined that there is no short-range interaction between the ion pairs; Finally, the ions with the same charge that have short-range interaction are combined into a first proximity coupling sequence, and the ions with different charges that have short-range interaction are combined into a second proximity coupling sequence.

5. A system based on the method according to any one of claims 1 to 4, characterized in that: include: A periodic structure model building module is used to build a periodic structure model for the molten salt system to be evaluated; A dynamic simulation module, which performs molecular dynamics simulation based on the periodic structure model to obtain ion motion trajectories and stable ion structures in a stable state; A parameter acquisition module, which acquires the displacement matrix and Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure; The calculation module is used to introduce the correlation coefficient of each ion pair, and calculate the ion migration number in the molten salt system using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient.

6. A terminal, characterized in that: The invention comprises a processor and a memory, wherein the memory stores a computer program, and the processor calls the computer program to implement: Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation; Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure; The correlation coefficient of each ion pair is introduced, and the ion migration number in the molten salt system is calculated using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient; Among them, molecular dynamics simulations were performed based on the periodic structural model of the molten salt system to be evaluated; The correlation coefficient of each ion pair is divided into the correlation coefficient of the same type of ion pairs and the correlation coefficient of different types of ion pairs; The calculation formula of the ion migration number with the correlation coefficient of each ion pair introduced is as follows: in, is the ion migration number of ion i in the molten salt system, is the correlation coefficient of the same ion pair ii, which means that in the same ion pair ii, ion i is affected by the migration correlation of the same ion i; is the correlation coefficient of heterogeneous ion pair ij, which means that in heterogeneous ion pair ij, ion i is affected by the migration correlation of heterogeneous ion j, and always satisfies Zi and Zj are the Mulliken charges of ion i and ion j, respectively. Δi(t), Δ j (t) represent the displacement of ion i and ion j at time t respectively.

7. A readable storage medium, characterized in that: A computer program is stored, which is called by a processor to implement: Obtain the ion motion trajectory and stable ion structure under the stable state obtained by dynamic simulation; Obtaining a displacement matrix and a Mulliken charge distribution of each ion based on the ion motion trajectory and the stable ion structure; The correlation coefficient of each ion pair is introduced, and the ion migration number in the molten salt system is calculated using the displacement matrix of each ion, the Mulliken charge distribution and the correlation coefficient; Among them, molecular dynamics simulations were performed based on the periodic structural model of the molten salt system to be evaluated; The correlation coefficient of each ion pair is divided into the correlation coefficient of the same type of ion pairs and the correlation coefficient of different types of ion pairs; The calculation formula of the ion migration number with the correlation coefficient of each ion pair introduced is as follows: in, is the ion migration number of ion i in the molten salt system, is the correlation coefficient of the same ion pair ii, which means that in the same ion pair ii, ion i is affected by the migration correlation of the same ion i; is the correlation coefficient of heterogeneous ion pair ij, which means that in heterogeneous ion pair ij, ion i is affected by the migration correlation of heterogeneous ion j, and always satisfies Zi and Zj are the Mulliken charges of ion i and ion j, respectively. Δi(t), Δ j (t) represent the displacement of ion i and ion j at time t respectively.

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