Lithium oxide gradient doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte and preparation method thereof
By introducing a lithium oxide concentration gradient into the lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte, the problems of lithium dendrite penetration and interface instability in lithium metal batteries were solved, achieving high ionic conductivity and interface stability of the electrolyte and improving the performance of all-solid-state batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- GUANGZHOU GUANGHUA BOYUE NEW ENERGY CO LTD
- Filing Date
- 2026-02-25
- Publication Date
- 2026-05-12
AI Technical Summary
Existing lithium-phosphorus-sulfur-chlorine electrolytes in lithium metal batteries suffer from problems such as a surge in interfacial resistance and dendrite penetration, making it difficult to resolve the contradiction between high ionic conductivity and interfacial instability.
A lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte with lithium oxide gradient doping is adopted. By setting a lithium oxide concentration gradient along the thickness direction of the electrolyte, the surface layer has a lithium oxide molar content of 5%-15% and the central layer has a lithium oxide molar content of 0.5%-3%. The concentration gradient structure is formed by hot pressing and sintering to suppress the risk of interface delamination and vertical penetration of lithium dendrites.
It effectively avoids stress concentration caused by sudden concentration changes, improves interface stability and ionic conductivity, inhibits the longitudinal penetration of lithium dendrites, and enhances the electrochemical and mechanical performance of the battery.
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Figure CN122025762A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of battery manufacturing technology, and more specifically, to a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte and its preparation method. Background Technology
[0002] Lithium-phosphorus-sulfur-chlorine electrolytes are typically composed of lithium salts (such as LiCl), phosphorus-sulfur compounds (such as P2S5), and doping elements, forming a glassy or crystalline structure. They are sulfide solid electrolytes and are core materials for all-solid-state lithium batteries, possessing high ionic conductivity and good mechanical ductility.
[0003] As one of the most studied sulfide electrolytes in recent years, lithium phosphorus sulfide chloride (LPSC) boasts high ionic conductivity and relatively low cost. However, its poor stability and incompatible positive and negative electrode materials limit its practical application. Composite solid-state electrolytes, on the other hand, exhibit excellent electrochemical and mechanical properties. To improve performance, researchers often prepare composite solid-state electrolytes through polymer modification (such as PEO and PMMA) to improve interfacial contact and electrochemical stability, aiming to enhance the interfacial compatibility and electrochemical stability of LPSCs. Despite these challenges, LPSCs remain a popular research direction in all-solid-state batteries due to their high ionic conductivity and low cost.
[0004] The existing Li6PS5Cl system readily undergoes side reactions with lithium metal, generating high-resistivity interfacial phases (such as Li2S and P2S). X This leads to a surge in interfacial resistance and dendrite penetration, highlighting the core contradiction between high ionic conductivity and interfacial instability. Summary of the Invention
[0005] Based on this, in order to suppress the vertical penetration of lithium dendrites, the present invention provides a lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte with lithium oxide gradient doping and its preparation method, the specific technical solution of which is as follows:
[0006] A lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, the main component of which is There is a lithium oxide concentration gradient along the thickness direction of the electrolyte, with a lithium oxide molar content of 5%-15% in the surface layer and 0.5%-3% in the middle layer; Where 0.05≤x≤0.8, 0.01≤y≤0.3.
[0007] The lithium oxide gradient-doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte can avoid stress concentration caused by sudden concentration changes, suppress the risk of interface delamination, and prevent the vertical penetration of lithium dendrites by setting a lithium oxide concentration gradient along the electrolyte thickness direction.
[0008] Preferably, the lithium oxide concentration decreases exponentially from the surface to the center to avoid abrupt interfacial stress due to a linear gradient.
[0009] Preferably, the lithium oxide concentration is based on a concentration distribution function. ; in, These represent the surface lithium oxide molar concentration and the central lithium oxide molar concentration of the solid electrolyte, respectively. These represent the normalized thickness coordinates and the concentration peak offset factor, respectively. Represents the gradient steepness factor. Indicates position The concentration of lithium oxide at that location.
[0010] A method for preparing lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, used to prepare the aforementioned lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0011] Preferably, the preparation method includes: first hot-pressing the surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, and then sintering the core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0012] Preferably, in 280 -350 The surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte was hot-pressed at low temperature and then heated at 450°C. The core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte is sintered at a high temperature of -550℃ to form a concentration gradient structure.
[0013] Preferably, the preparation method includes: Obtain the basic oxygen doping level and the oxygen doping activation threshold; Based on the aforementioned basic oxygen doping amount, oxygen doping activation threshold, and location A model for effective oxygen doping was constructed based on the lithium oxide concentration at the given location. The effective oxygen doping level is obtained based on the effective oxygen doping level model.
[0014] Preferably, the preparation method further includes: To obtain the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot pressing pressure; A dual-activation-energy sintering kinetic model is constructed based on the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot-pressing pressure. The densification rate was obtained based on the dual activation energy sintering kinetics model.
[0015] Preferably, the dual activation energy sintering kinetic model is expressed as follows: ; in, These represent the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot-pressing pressure, respectively. Let A and B represent the ideal gas constant, absolute temperature, and pressure sensitivity index, respectively. Let A and B represent the kinetic factors for low-temperature and high-temperature processes, respectively. This represents the densification rate.
[0016] Preferably, the hot pressing pressure is between 30MPa and 100MPa. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to its embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not limit the scope of protection of the invention.
[0018] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly attached to the other element or there may be an intervening element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.
[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.
[0020] In this invention, "first" and "second" do not represent a specific quantity or order, but are merely used to distinguish names.
[0021] Example 1: This embodiment provides a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, the main component of which is... There is a lithium oxide concentration gradient along the thickness direction of the electrolyte, with a lithium oxide molar content of 5%-15% in the surface layer and 0.5%-3% in the central layer; where 0.05≤x≤0.8, 0.01≤y≤0.3.
[0022] The lithium oxide concentration gradient can be controlled by a Gaussian function or a piecewise function to more accurately control the lithium oxide content in different regions, thereby suppressing dendrites.
[0023] As a preferred technical solution, the lithium oxide concentration decreases exponentially from the surface to the center to avoid abrupt interfacial stress due to linear gradient.
[0024] For example, the lithium oxide concentration is based on a concentration distribution function. ;in, These represent the surface lithium oxide molar concentration and the central lithium oxide molar concentration of the solid electrolyte, respectively. These represent the normalized thickness coordinates and the concentration peak offset factor along the thickness direction, respectively. Represents the gradient steepness factor. Indicates position The concentration of lithium oxide at that location.
[0025] Specifically, the gradient steepness factor is generally between 0.15 and 0.3, used to control the width of the transition region. The concentration peak offset factor is between 0.65 and 0.75, preferably 0.7. When z=0, the position is at the center of the electrolyte; when z=1, the position is at the surface of the electrolyte. The surface lithium oxide molar concentration can improve interface stability and dendrite suppression, while the central lithium oxide molar concentration can maintain the core region with high ionic conductivity. Generally, when σ<0.15, the gradient is too steep and prone to stratification; when σ>0.3, the concentration transition is slow and the gradient advantage is lost. σ is preferably set between 2.0 and 2.4 to balance ionic conductivity and compressive strength. Traditional gradient models usually set the concentration peak offset factor = 1 to achieve symmetrical distribution. In this embodiment, the offset of the concentration peak offset factor can achieve surface thickening, which can effectively enhance the buffering capacity against the volume expansion of lithium metal.
[0026] By adjusting the gradient steepness factor and the concentration peak offset factor, the concentration distribution function can be adapted to different sulfide systems (such as LPS, LGPS, etc.). This concentration distribution function also exhibits multiphysics system effects; specifically, it is generated through surface high-lithium oxide formation. The passivation layer enhances electronic insulation and suppresses dendrite formation; its gradient concentration reduces the enthalpy change of interfacial side reactions and improves interfacial stability; the central low-lithium oxide region maintains high Li content. + Mobility, high oxygen doping on the surface can broaden Li mobility + Channels are used to optimize ion conductivity.
[0027] In summary, the lithium oxide gradient-doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte, by setting a lithium oxide concentration gradient along the electrolyte thickness direction, can avoid stress concentration caused by abrupt concentration changes, suppress the risk of interface delamination, and prevent the vertical penetration of lithium dendrites.
[0028] This embodiment also provides a method for preparing lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, which is used to prepare the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0029] The preparation method includes: first hot-pressing the surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, and then sintering the core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0030] Specifically, first at 280 -350 The surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte was hot-pressed at low temperature, and then heated at 450°C. The core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte is sintered at a high temperature of -550℃ to form a concentration gradient structure.
[0031] As a preferred technical solution, the preparation method includes the following steps: S1, Obtain the basic oxygen content and oxygen doping activation threshold .
[0032] Specifically, the oxygen doping activation threshold is the critical Li₂O concentration that triggers the decrease in the oxygen ion migration energy barrier, which can be determined experimentally. The basic oxygen doping amount is the preset O / (S+Cl) molar ratio in the formulation, used to control the intrinsic ionic conductivity of the electrolyte.
[0033] S2, based on the basic oxygen doping amount, oxygen doping activation threshold, and location A model for effective oxygen doping was constructed based on the lithium oxide concentration at the given location.
[0034] S3, Obtain the effective oxygen doping amount according to the effective oxygen doping amount model.
[0035] Effective oxygen doping amount is the amount of O that actually enters the crystal lattice and replaces S / Cl. 2- The ratio determines the width of the Li+ migration channel and the lattice energy.
[0036] For example, the effective oxygen doping level model is expressed as: The basic oxygen content is generally between 0.01 and 0.3. This represents the enhancement factor of lithium oxide to oxygen doping, typically set to 0.2. It is used to quantify the ability of Li₂O to improve oxygen doping efficiency; a larger value indicates a higher gradient design benefit. Li₂O is mainly used to improve oxygen doping efficiency and strengthen the migration channels of Li⁺ at grain boundaries.
[0037] More specifically, when the position The lithium oxide concentration at this location is much lower than the oxygen doping activation threshold, and the effective oxygen doping amount is approximately equal to the basic oxygen doping amount; when the position The lithium oxide concentration at that location is much greater than the oxygen doping activation threshold. Therefore, this effective oxygen doping model exhibits a nonlinear enhancement effect due to its logarithmic function characteristics. Furthermore, high effective oxygen doping can expand Li+ migration channels, improve ionic conductivity, generate a Li3PO4-Li2O composite phase in the oxygen-rich surface region, which can enhance the electron tunneling barrier and improve interface passivation. Additionally, oxygen doping can compensate for sulfur volatilization and optimize lattice stability; thus, this model also possesses a gradient synergistic optimization mechanism.
[0038] As a preferred technical solution, the preparation method further includes the following steps: S4, to obtain the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot pressing pressure.
[0039] S5. Construct a dual-activation-energy sintering kinetic model based on the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot-pressing pressure.
[0040] S6. Obtain the densification rate according to the dual activation energy sintering kinetics model.
[0041] For example, the dual activation energy sintering kinetic model is expressed as follows: ;in, These represent the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot-pressing pressure, respectively. Let A and B represent the ideal gas constant, absolute temperature, and pressure sensitivity index, respectively. Let A and B represent the kinetic factors for low-temperature and high-temperature processes, respectively. This represents the densification rate.
[0042] Specifically, the hot-pressing pressure is between 30 MPa and 100 MPa, used to promote particle rearrangement and porosity elimination. The low-temperature process kinetic factor characterizes the diffusion efficiency of the surface Li2O-rich region; a higher value indicates higher low-temperature sintering activity. The high-temperature process kinetic factor is used to control the lattice rearrangement rate of the core sulfide. The low-temperature sintering activation energy is the energy barrier for densification of the surface Li2O-rich region; a low activation energy ensures 280°C. -350 Sintering is complete. The high-temperature sintering activation energy serves as the energy barrier for the growth of the core Li6PS5Cl grains. The pressure sensitivity index is used to quantify the enhancing effect of pressure on densification; the default value is 0.8, indicating efficiency saturation under high pressure.
[0043] In the dual activation energy sintering kinetics model These are the low-temperature dominant term and the high-temperature dominant term, respectively. In the low-temperature dominant term, due to the viscous flow of the Li2O-rich surface layer at low temperatures, through thermal pressure... This can accelerate pore closure, thus the low-temperature sintering activation energy matches the Li2O plastic deformation energy barrier, suppressing sulfur volatilization. In the high-temperature dominant term, since volume diffusion dominates in this state, high temperature activates sulfide lattice migration, achieving grain fusion, which is independent of pressure, thus ensuring grain densification. In the transition region, the low-temperature and high-temperature dominant terms work synergistically to avoid delamination caused by abrupt rate changes. Therefore, this dual-activation-energy sintering kinetic model has the characteristics of dual-mechanism synergistic densification.
[0044] In summary, based on this dual activation energy sintering kinetics model, the low-temperature term is effective when T < 400°C. It can contribute 90% densification, greatly improving the sulfur retention rate. The high pressure on the surface can break up soft agglomerates, while the low pressure in the core can prevent abnormal grain growth. At the same time, it can match the plastic deformation of Li2O and the diffusion of sulfides on a microscopic level, and prevent interlayer delamination on a macroscopic level.
[0045] Example 2: This embodiment provides a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, the main component of which is... There is a lithium oxide concentration gradient along the thickness direction of the electrolyte, with a lithium oxide molar content of 5%-15% in the surface layer and 0.5%-3% in the central layer; where 0.05≤x≤0.8, 0.01≤y≤0.3.
[0046] Here, x represents the lithium vacancy concentration, used to control the number of Li+ vacancies and affect the ion migration channel density. Y represents the oxygen doping ratio, used to adjust PS4. 3- O in structural unit 2- Partially replaces S 2- / Cl - The ratio of [something] alters the stability of the anionic framework and the Li+ coordination environment.
[0047] Specifically, increasing x leads to higher lithium vacancy concentration, which in turn increases the probability of Li+ transitions, thus increasing ionic conductivity; increasing y leads to higher O2 concentration. 2- The high electronegativity of Li+ enhances the binding capacity of Li+, leading to an increased migration barrier. However, moderate oxygen doping (y = 0.1-0.2) can broaden the ion channels. Therefore, the ionic conductivity can be optimized by adjusting x and y.
[0048] A high y-value (y=0.2~0.3) on the surface can form a Li2O-rich interface layer, which improves electronic insulation. Gradient design can delay the longitudinal growth of dendrites and the critical current density, thereby suppressing lithium dendrite penetration. 2- Doping can suppress sulfur volatilization and raise the interfacial energy barrier; when x>0.5 and y<0.15, it can prevent sulfur vacancy overloading from causing cell distortion and ensure structural stability. Therefore, by adjusting x and y, interfacial stability can be enhanced.
[0049] In the two-step sintering process, the surface layer is formed at low temperature, with y taking the upper limit (0.25-0.3) and x taking the lower limit (0.05-0.2) to suppress sulfur volatilization. The core layer is densified at high temperature: x taking 0.5-0.8 and y taking 0.01-0.1 can improve density. Parameters x and y have a coupling effect. Low x + high y leads to a decrease in conductivity but an increase in interface stability, suitable for the electrolyte surface layer; high x + low y leads to an increase in conductivity but also an increase in the risk of sulfur volatilization, suitable for the electrolyte core layer, combined with the low-temperature sintering process. Based on experience, x≈0.3 and y≈0.15 can be selected, which is the balance point between conductivity and stability.
[0050] The lithium oxide concentration gradient can be controlled by a Gaussian function or a piecewise function to more accurately control the lithium oxide content in different regions, thereby suppressing dendrites.
[0051] As a preferred technical solution, the lithium oxide concentration decreases exponentially from the surface to the center to avoid abrupt interfacial stress due to linear gradient.
[0052] For example, the lithium oxide concentration is based on a concentration distribution function. ;in, These represent the surface lithium oxide molar concentration and the central lithium oxide molar concentration of the solid electrolyte, respectively. These represent the normalized thickness coordinates and the concentration peak offset factor along the thickness direction, respectively. Represents the gradient steepness factor. Indicates position The concentration of lithium oxide at that location.
[0053] Specifically, the gradient steepness factor is generally between 0.15 and 0.3, used to control the width of the transition region. The concentration peak offset factor is between 0.65 and 0.75, preferably 0.7. When z=0, the position is at the center of the electrolyte; when z=1, the position is at the surface of the electrolyte. The surface lithium oxide molar concentration can improve interface stability and dendrite suppression, while the central lithium oxide molar concentration can maintain the core region with high ionic conductivity. Generally, when σ<0.15, the gradient is too steep and prone to stratification; when σ>0.3, the concentration transition is slow and the gradient advantage is lost. σ is preferably set between 2.0 and 2.4 to balance ionic conductivity and compressive strength. Traditional gradient models usually set the concentration peak offset factor = 1 to achieve symmetrical distribution. In this embodiment, the offset of the concentration peak offset factor can achieve surface thickening, which can effectively enhance the buffering capacity against the volume expansion of lithium metal.
[0054] By adjusting the gradient steepness factor and the concentration peak offset factor, the concentration distribution function can be adapted to different sulfide systems (such as LPS, LGPS, etc.). This concentration distribution function also exhibits multiphysics system effects; specifically, it is generated through surface high-lithium oxide formation. The passivation layer enhances electronic insulation and suppresses dendrite formation; its gradient concentration reduces the enthalpy change of interfacial side reactions and improves interfacial stability; the central low-lithium oxide region maintains high Li content. + Mobility, high oxygen doping on the surface can broaden Li mobility + Channels are used to optimize ion conductivity.
[0055] In summary, the lithium oxide gradient-doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte, by setting a lithium oxide concentration gradient along the electrolyte thickness direction, can avoid stress concentration caused by abrupt concentration changes, suppress the risk of interface delamination, and prevent the vertical penetration of lithium dendrites.
[0056] Because the Li2O concentration distribution function during surface sintering in actual production is affected by the mold heat capacity, resulting in boundary effects, a compensation function can be used to address this. Perform corrections. The corrected position The lithium oxide concentration at the point. The parameters 0.2 and -5 can be set according to the magnitude and rate of deviation of the edge region concentration from the theoretical value, or based on experience.
[0057] This embodiment also provides a method for preparing lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, which is used to prepare the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0058] The preparation method includes: first hot-pressing the surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, and then sintering the core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
[0059] Specifically, first at 280 -350 The surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte was hot-pressed at low temperature, and then heated at 450°C. The core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte is sintered at a high temperature of -550℃ to form a concentration gradient structure.
[0060] As a preferred technical solution, the preparation method includes the following steps: S1, Obtain the basic oxygen content and oxygen doping activation threshold .
[0061] Specifically, the oxygen doping activation threshold is the critical Li₂O concentration that triggers the decrease in the oxygen ion migration energy barrier, which can be determined experimentally. The basic oxygen doping amount is the preset O / (S+Cl) molar ratio in the formulation, used to control the intrinsic ionic conductivity of the electrolyte.
[0062] S2, based on the basic oxygen doping amount, oxygen doping activation threshold, and location A model for effective oxygen doping was constructed based on the lithium oxide concentration at the given location.
[0063] S3, Obtain the effective oxygen doping amount according to the effective oxygen doping amount model.
[0064] Effective oxygen doping amount is the amount of O that actually enters the crystal lattice and replaces S / Cl. 2- The ratio determines the width of the Li+ migration channel and the lattice energy.
[0065] For example, the effective oxygen doping level model is expressed as: The basic oxygen content is generally between 0.01 and 0.3. This represents the enhancement factor of lithium oxide to oxygen doping, typically set to 0.2. It is used to quantify the ability of Li₂O to improve oxygen doping efficiency; a larger value indicates a higher gradient design benefit. Li₂O is mainly used to improve oxygen doping efficiency and strengthen the migration channels of Li⁺ at grain boundaries.
[0066] More specifically, when the position The lithium oxide concentration at this location is much lower than the oxygen doping activation threshold, and the effective oxygen doping amount is approximately equal to the basic oxygen doping amount; when the position The lithium oxide concentration at that location is much greater than the oxygen doping activation threshold. Therefore, this effective oxygen doping model exhibits a nonlinear enhancement effect due to its logarithmic function characteristics. Furthermore, high effective oxygen doping can expand Li+ migration channels, improve ionic conductivity, generate a Li3PO4-Li2O composite phase in the oxygen-rich surface region, which can enhance the electron tunneling barrier and improve interface passivation. Additionally, oxygen doping can compensate for sulfur volatilization and optimize lattice stability; thus, this model also possesses a gradient synergistic optimization mechanism.
[0067] As a preferred technical solution, the preparation method further includes the following steps: S4, to obtain the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot pressing pressure.
[0068] S5. Construct a dual-activation-energy sintering kinetic model based on the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot-pressing pressure.
[0069] S6. Obtain the densification rate according to the dual activation energy sintering kinetics model.
[0070] For example, the dual activation energy sintering kinetic model is expressed as follows: ;in, These represent the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot-pressing pressure, respectively. Let A and B represent the ideal gas constant, absolute temperature, and pressure sensitivity index, respectively. Let A and B represent the kinetic factors for low-temperature and high-temperature processes, respectively. This represents the densification rate.
[0071] Specifically, the hot-pressing pressure is between 30 MPa and 100 MPa, used to promote particle rearrangement and porosity elimination. The low-temperature process kinetic factor characterizes the diffusion efficiency of the surface Li2O-rich region; a higher value indicates higher low-temperature sintering activity. The high-temperature process kinetic factor is used to control the lattice rearrangement rate of the core sulfide. The low-temperature sintering activation energy is the energy barrier for densification of the surface Li2O-rich region; a low activation energy ensures 280°C. -350 Sintering is complete. The high-temperature sintering activation energy serves as the energy barrier for the growth of the core Li6PS5Cl grains. The pressure sensitivity index is used to quantify the enhancing effect of pressure on densification; the default value is 0.8, indicating efficiency saturation under high pressure.
[0072] In the dual activation energy sintering kinetics model These are the low-temperature dominant term and the high-temperature dominant term, respectively. In the low-temperature dominant term, due to the viscous flow of the Li2O-rich surface layer at low temperatures, through thermal pressure... This can accelerate pore closure, thus the low-temperature sintering activation energy matches the Li2O plastic deformation energy barrier, suppressing sulfur volatilization. In the high-temperature dominant term, since volume diffusion dominates in this state, high temperature activates sulfide lattice migration, achieving grain fusion, which is independent of pressure, thus ensuring grain densification. In the transition region, the low-temperature and high-temperature dominant terms work synergistically to avoid delamination caused by abrupt rate changes. Therefore, this dual-activation-energy sintering kinetic model has the characteristics of dual-mechanism synergistic densification.
[0073] In summary, based on this dual activation energy sintering kinetics model, the low-temperature term is effective when T < 400°C. It can contribute 90% densification, greatly improving the sulfur retention rate. The high pressure on the surface can break up soft agglomerates, while the low pressure in the core can prevent abnormal grain growth. At the same time, it can match the plastic deformation of Li2O and the diffusion of sulfides on a microscopic level, and prevent interlayer delamination on a macroscopic level.
[0074] The partial pressure of sulfur is crucial in electrolyte sintering. Excessive sulfur partial pressure leads to sulfur volatilization and loss, affecting the stoichiometry of the electrolyte; conversely, insufficient partial pressure may trigger decomposition reactions. Therefore, this embodiment also provides a sulfur partial pressure equation. It expresses thermodynamic parameters (such as the enthalpy change of sulfur volatilization) in exponential form. and absolute temperature T) and intrinsic material parameters (effective oxygen doping amount) This is related to the control of the sintering atmosphere.
[0075] Specifically This refers to the partial pressure of sulfur vapor, i.e., the actual pressure of sulfur in the sintering atmosphere, used to suppress excessive sulfur volatilization, and is generally around 10. -5 -10 -2 atm, preferably 10 -4 . The vapor pressure constant, used as a reference, can be understood as the limiting vapor pressure of pure Li₂S at infinite temperature. The enthalpy change of sulfur into the activation energy of the Li₂S decomposition reaction indicates a higher sulfur retention capacity. This represents the oxygen doping suppression coefficient, used to quantify the strength of the inhibitory effect of oxygen occupancy on sulfur volatilization. The larger the value, the higher the gradient design benefit, and it is generally set between 3.0 and 4.5.
[0076] Traditional sulfur partial pressure equations do not consider the inhibitory effect of oxygen doping on sulfur vacancies, which can easily lead to increased prediction errors. Compared to traditional sulfur partial pressure equations, since the surface region with high effective oxygen doping requires a lower sulfur partial pressure to suppress volatilization, the sulfur partial pressure equation in this embodiment increases... The correction term allows oxygen ions to occupy sulfur sites, reducing the sulfur vacancy concentration and thus shifting the sulfur volatilization equilibrium to the left. In other words, the sulfur partial pressure equation in this embodiment passes through the intrinsic volatilization energy barrier (…). ) and oxygen doping suppression effect ( The dual regulation of oxygen doping corrects the physical model for calculating sulfur partial pressure at the thermodynamic level, and for the first time quantifies the blocking effect of oxygen doping on sulfur vacancies. It can achieve the synergistic goal of high sulfur retention and stable composition, accurately suppressing surface volatilization and preventing core decomposition.
[0077] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0078] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.
Claims
1. A lithium oxide gradient-doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte, characterized in that, The main component of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte is There is a lithium oxide concentration gradient along the thickness direction of the electrolyte, with a lithium oxide molar content of 5%-15% in the surface layer and 0.5%-3% in the middle layer; Where 0.05≤x≤0.8, 0.01≤y≤0.
3.
2. The lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in claim 1, characterized in that, The lithium oxide concentration decreases exponentially from the surface to the center to avoid abrupt interfacial stress due to linear gradients.
3. The lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in claim 2, characterized in that, The lithium oxide concentration is based on a concentration distribution function. ; in, These represent the surface lithium oxide molar concentration and the central lithium oxide molar concentration of the solid electrolyte, respectively. These represent the normalized thickness coordinates and the concentration peak offset factor, respectively. Represents the gradient steepness factor. Indicates position The concentration of lithium oxide at that location.
4. A method for preparing a lithium oxide gradient-doped lithium-phosphorus-sulfur-chlorine-oxygen solid electrolyte, characterized in that, Used to prepare lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in any one of claims 1-3.
5. The method for preparing a lithium oxide gradient-doped lithium phosphorus-sulfur-chlorine-oxygen solid electrolyte as described in claim 4, characterized in that, The preparation method includes: first hot-pressing the surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte, and then sintering the core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte.
6. The method for preparing a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in claim 5, characterized in that, In 280 -350 The surface layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte was hot-pressed at low temperature and then heated at 450°C. The core layer of the lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte is sintered at a high temperature of -550℃ to form a concentration gradient structure.
7. The method for preparing a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in claim 6, characterized in that, The preparation method includes: Obtain the basic oxygen doping level and the oxygen doping activation threshold; Based on the aforementioned basic oxygen doping amount, oxygen doping activation threshold, and location A model for effective oxygen doping was constructed based on the lithium oxide concentration at the given location. The effective oxygen doping level is obtained based on the effective oxygen doping level model.
8. The method for preparing a lithium oxide gradient-doped lithium phosphorus sulfur chlorine oxygen solid electrolyte as described in claim 7, characterized in that, The preparation method further includes: To obtain the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot pressing pressure; A dual-activation-energy sintering kinetic model is constructed based on the low-temperature sintering activation energy, high-temperature sintering activation energy, and hot-pressing pressure. The densification rate was obtained based on the dual activation energy sintering kinetics model.
9. The method for preparing a lithium oxide gradient-doped lithium phosphorus-sulfur-chlorine-oxygen solid electrolyte as described in claim 8, characterized in that, The dual activation energy sintering kinetic model is expressed as follows: ; in, These represent the activation energy for low-temperature sintering, the activation energy for high-temperature sintering, and the hot-pressing pressure, respectively. Let A and B represent the ideal gas constant, absolute temperature, and pressure sensitivity index, respectively. Let A and B represent the kinetic factors for low-temperature and high-temperature processes, respectively. This represents the densification rate.
10. The method for preparing a lithium oxide gradient-doped lithium phosphorus-sulfur-chlorine-oxygen solid electrolyte as described in claim 9, characterized in that, The hot pressing pressure is between 30MPa and 100MPa.