Solid electrolyte material, manufacturing method, electrolyte layer, and lithium-ion battery

Abstract

This invention relates to a solid electrolyte material for lithium-ion batteries, and more specifically to a solid electrolyte material, a manufacturing method, an electrolyte layer, and a lithium-ion battery, wherein its chemical formula is Li a P b C m S d O n Cl f Here, 5.4 ≤ a ≤ 6.1, 0.9 ≤ b ≤ 1, 0

Description

[Technical Field]

[0001] <Cross-reference of related applications> This application is filed based on and claims priority from the said Chinese patent application, application number 202311740704.8, with a filing date of December 18, 2023. All contents of the said Chinese patent application are incorporated into this application by reference.

[0002] The present invention relates to the technical field of solid electrolyte materials for lithium-ion batteries, and more specifically to solid electrolyte materials, manufacturing methods, electrolyte layers, and lithium-ion batteries. [Background technology]

[0003] In recent years, while sales of new energy vehicles in China have been increasing year by year, safety accidents related to power batteries have become frequent, making how to improve the safety of power batteries a focus of the power battery industry. Currently commercialized lithium-ion power batteries use organic liquid electrolytes as lithium-ion transmission media, and due to their strong volatility and flammability, safety risks exist during the battery charging and discharging process. Compared to liquid batteries, all-solid-state batteries use non-flammable solid electrolytes instead of liquid electrolytes, offering higher safety and energy density, and are considered the most promising new generation of power battery technology. Sulfide solid electrolytes have good mechanical ductility and high ionic conductivity comparable to liquid electrolytes, making them one of the solid electrolyte materials with the highest applicability in the field of all-solid-state batteries.

[0004] Among different types of sulfide electrolytes, argyrodite-type sulfide solid electrolytes such as Li6PS5Cl have attracted widespread attention from academia and industry due to their high room-temperature ionic conductivity, excellent mechanical properties, and good negative electrode interface stability. However, argyrodite-type electrolytes still have drawbacks, such as poor air stability and poor compatibility with oxide cathodes, which hinder their practical application. On the one hand, argyrodite-type electrolytes are highly reactive with moisture in the air, and even in dry rooms or inert gas glove boxes with extremely low water content, they still react with trace amounts of moisture in the environment, causing performance degradation. This makes their manufacturing and usage conditions excessively strict, preventing them from meeting the needs of industrial mass production. On the other hand, their poor compatibility with oxide cathode materials results in insufficient battery cycle stability when used with oxide cathodes. This is mainly related to the low oxidation stability potential of the sulfide itself, which makes it easily oxidized by the cathode during the electrochemical cycle. [Overview of the project] [Problems that the invention aims to solve]

[0005] The object of the present invention is to provide a solid electrolyte material, a manufacturing method, an electrolyte layer, and a lithium-ion battery that improve air stability and compatibility stability with an oxide cathode. [Means for solving the problem]

[0006] To solve the above problem, the present invention relates to a chemical formula Li a P b C m S d O n Cl f We provide a sulfide solid electrolyte material where 5.4 ≤ a ≤ 6.1, 0.9 ≤ b ≤ 1, 0 <m≦0.1、4.1≦d≦5、0<n≦0.3、1≦f≦1.7である。

[0007] In another aspect of the present invention, preferably, 0.01 ≤ m ≤ 0.05 and 0.05 ≤ n ≤ 0.2.

[0008] In another aspect of the present invention, preferably, 5.4 ≤ a ≤ 5.6, 0.95 ≤ b ≤ 1, 4.3 ≤ d ≤ 4.6, and 1.4 ≤ f ≤ 1.6.

[0009] In another aspect of the present invention, preferably, the sulfide solid electrolyte material has an ionic conductivity of ≥ 5 × 10 -3 Electronic conductivity < 10 × 10 in S / cm -9 The ionic conductivity retention rate is >50% after being left for 24 hours at S / cm and -45°C dew point.

[0010] In another aspect of the present invention, preferably, a method for producing the sulfide solid electrolyte material, Step 100 involves mixing raw materials for forming a sulfide solid electrolyte material and performing polishing mixing to obtain a first reactant, Step 200 involves placing the first reactant in a quartz tube, evacuating and sealing it, then firing and polishing it to obtain a second reactant. The method includes step 300, which involves heating the second reactant under the protection of an inert gas and passing a carbon-containing gas through it to obtain a sulfide solid electrolyte material.

[0011] In another aspect of the present invention, preferably, the raw materials for the sulfide solid electrolyte material include Li2S, P2S5, LiCl, and Li2O.

[0012] In another aspect of the present invention, preferably, step 200, which involves placing the first reactant in a quartz tube, evacuating and sealing it, then firing and polishing it to obtain a second reactant, The vacuum level used for sealing after vacuuming is ≤ 50 Pa, The firing process includes raising the temperature from room temperature to 400-600°C over 30-120 minutes, and then maintaining the temperature for a predetermined period of time.

[0013] In another aspect of the present invention, preferably, the carbon-containing gas comprises at least one of CS2 or CCl4, and the permeation flow rate of the carbon-containing gas is 1 to 20 L / min.

[0014] In another aspect of the present invention, preferably, an electrolyte layer comprising the above-mentioned sulfide solid electrolyte material or a sulfide solid electrolyte material produced by the above-mentioned method, wherein the electrolyte layer is formed by pressure molding the sulfide solid electrolyte material.

[0015] In another aspect of the present invention, preferably a lithium-ion battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode and the negative electrode, wherein the solid electrolyte layer comprises the sulfide solid electrolyte material, the sulfide solid electrolyte material produced by the above-mentioned manufacturing method, or the electrolyte layer. [Effects of the Invention]

[0016] The above-described technical proposal of the present invention has the following beneficial technical effects. This invention relates to a solid electrolyte material obtained by co-doping an algyrodite-type sulfide electrolyte with two elements, O and C. The resulting solid electrolyte material maintains the excellent properties inherent in the electrolyte material, such as high ionic conductivity, good mechanical strength, and excellent negative electrode stability, while effectively improving the air stability and positive electrode stability of the electrolyte, thereby significantly enhancing its overall performance and practical value. [Brief explanation of the drawing]

[0017] [Figure 1] This is an X-ray diffraction spectrum diagram of the Li5.54P0.96C0.04S4.4O0.1Cl1.5 electrolyte in Example 1 provided by the present invention. [Figure 2] This is an electrochemical impedance spectrum diagram of the Li5.54P0.96C0.04S4.4O0.1Cl1.5 electrolyte in Example 1 provided by the present invention. [Modes for carrying out the invention]

[0018] To make the objectives, technical solutions, and advantages of the present invention more clear, the present invention will be described in more detail below with reference to the drawings in conjunction with specific embodiments. It should be understood that these descriptions are merely exemplary and do not limit the scope of the present invention. In addition, in the following descriptions, to avoid unnecessary confusion of the concepts of the present invention, the descriptions of well-known structures and technologies are omitted.

[0019] It is clear that the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the present invention.

[0020] In addition, in the description of the present invention, it should be understood that the terms "first", "second", and "third" are only used for the purpose of description and cannot indicate or imply relative importance.

[0021] In addition, the technical features according to different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0022] (Embodiment) A sulfide solid electrolyte material, the chemical formula of which is Li a P b C m S d O n Cl f where 5.4 ≤ a ≤ 6.1, 0.9 ≤ b ≤ 1, 0 < m ≤ 0.1, 4.1 ≤ d ≤ 5, 0 < n ≤ 0.3, 1 ≤ f ≤ 1.7.

[0023] The sulfide solid electrolyte provided by the present invention is obtained by co-doping two elements, O and C, into a Li6PS5Cl-based argyrodite-type sulfide solid electrolyte.

[0024] It is a conventional technique to improve the air stability of Li6PS5Cl-based algyrodite-type sulfide solid electrolytes by doping with oxygen (O). The main principle is to replace some of the sulfur (S) with oxygen, thereby forming more stable PO bonds in the crystal structure instead of the easily hydrolyzable PS bonds, and thereby improving the air stability of the electrolyte. However, while PO bonds are formed, the Li-S bonds, which originally have weak bond energy and are favorable for lithium ion transport, are also partially replaced by Li-O bonds, which have stronger bond energy and are unfavorable for lithium ion transport, leading to a decrease in the conductivity of the electrolyte ions. As shown in one comparative example of the present invention, a sulfide electrolyte doped with a small amount of oxygen shows an increase in the maintenance rate of room temperature ionic conductivity after 24 hours of exposure in a dew point environment of -45°C from 36.6% in the undoped state to 48.7%, while the initial room temperature ionic conductivity is 5.4 × 10⁻⁶ in the undoped state. -3 4.6 × 10 after doping from S / cm -3 It decreases to S / cm.

[0025] In this embodiment, doping the P site with C improves the ionic conductivity of the sulfide electrolyte. Because the radius of the C atom is smaller than that of the P atom, after elemental substitution, a wider lithium ion transport channel is formed in the crystal structure, thereby compensating for the adverse effect of O doping on ionic conductivity. In conventional techniques, P is generally doped using ions such as Al, Ga, In, Si, Ge, Sn, As, and Sb, while doping with C is difficult. The main reason is that the radius of the C atom is too small, resulting in a large difference from that of P, making it very difficult to dopify the lattice. If the lattice cannot be effectively doped and exists as an impurity, the electronic conductivity of the electrolyte increases, which seriously affects the performance of the electrolyte in batteries, particularly inducing lithium dendrites and causing battery failure.

[0026] In this example, by using CS2 or CCl4 as the carbon source and annealing the sulfide electrolyte in a CS2 or CCl4 atmosphere, doping of trace amounts of carbon into the lattice can be achieved. Analysis of the doped electrolyte revealed that it contains a considerable amount of carbon, with a mass fraction reaching up to 0.5%. However, the X-ray diffraction (XRD) spectrum of the electrolyte shows no impurity phases, and the electronic conductivity is 10 × 10⁻¹⁰. -9 It was found that the level could be maintained at a low level of less than S / cm.

[0027] O and C co-doped sulfide electrolytes possess both good air stability and room-temperature ionic conductivity. As shown in one embodiment of the present invention, an O and C co-doped sulfide electrolyte can achieve an ionic conductivity retention rate of 81.2% after 24 hours of exposure in a dew point environment of -45°C, and an initial ionic conductivity of 8.5 × 10⁻⁶. -3 It is possible to achieve a high level of S / cm.

[0028] While doping with 10C alone can improve the ionic conductivity of sulfide electrolytes, it cannot improve air stability. As shown in another comparative example of the present invention, a sulfide electrolyte doped with 10C alone has an initial ionic conductivity of 6.1 × 10⁻⁶. -3 Although the value is S / cm, the ionic conductivity retention rate after 24 hours of exposure in a dew point environment of -45°C is only 32.1%.

[0029] Whether doped alone or co-doped, the doping amounts of O and C are extremely limited. For example, when O is doped alone, if the doping amount is too high, a Li2O impurity phase will appear in the XRD spectrum of the electrolyte. When O and C are co-doped, if the doping amount is too high, a Li2CO3 impurity phase will appear in the XRD spectrum of the electrolyte. When C is doped alone, even if annealing is performed in either a CS2 or CCl4 atmosphere, there is an upper limit to the amount of C doped, not exceeding 0.5% at most. This explains that the reaction between CS2 and CCl4 and the electrolyte powder may occur only on the surface of the electrolyte particles. When a C content exceeding 0.5% is detected in the electrolyte, the electronic conductivity of the electrolyte also increases significantly. This explains that in this case, C no longer exists in a compound state doped into the lattice, but exists in the form of an element or other highly conductive impurity.

[0030] Unexpectedly, the sulfide electrolyte obtained by co-doping with O and C also exhibits significantly improved compatibility stability with the oxide cathode. As shown in another set of examples and comparative examples of the present invention, an all-solid-state demonstration battery manufactured using a sulfide electrolyte co-doped with O and C in combination with an NCM532 cathode still maintained a capacity retention rate of over 71.2% even after 250 cycles at a current density of 0.3C, significantly exceeding the data obtained with undoped electrolytes and electrolytes doped with O and C individually (60.8%, 63.4%, and 53.1%, respectively). Further research revealed the observation of a Li2CO3 phase at the electrolyte interface after cycling. Since there is no Li2CO3 impurity phase in the initial electrolyte, it is highly likely that this Li2CO3 phase was generated during the electrochemical cycling process. Based on this, it can be inferred that the scientific mechanism by which O and C co-doping improves electrolyte and cathode stability is that trace amounts of O and C in the electrolyte form a stable Li2CO3 intermediate layer at the interface between the cathode and electrolyte particles during the battery cycle process. This intermediate layer prevents continuous oxidation of the sulfide electrolyte during the cycle process, thereby significantly improving cycle stability.

[0031] In one embodiment of the present invention, further, Li a Pb C m S d O n Cl f The preferred components of the sulfide solid electrolyte material are 0.01≦m≦0.05, 0.05≦n≦0.2, 5.4≦a≦5.6, 0.95≦b≦1, 4.3≦d≦4.6, and 1.4≦f≦1.6.

[0032] Within that range, electrolytes exhibit higher ionic conductivity and superior overall performance.

[0033] In one embodiment of the present invention, the sulfide solid electrolyte material further has an ionic conductivity of ≥ 5 × 10 -3 S / cm, electronic conductivity <10 × 10⁻¹⁰ -9 The ionic conductivity retention rate after being left for 24 hours at S / cm and -45°C dew point is >50%. Furthermore, the sulfide solid electrolyte material has an ionic conductivity of ≥6 × 10⁻⁶. -3 It is S / cm.

[0034] The embodiments of sulfide electrolyte materials and methods for producing the same will be further described below with reference to specific examples of the present invention. Unless otherwise specified, the raw materials used in each embodiment are commercially available, and unless otherwise specified, the process conditions are general operating conditions.

[0035] A method for producing the above-mentioned sulfide solid electrolyte material, Step 100 is a step of mixing raw materials for forming a sulfide solid electrolyte material and performing polishing mixing to obtain a first reactant, wherein the raw materials for the sulfide solid electrolyte material include Li2S, P2S5, LiCl and Li2O. Step 200 is a step in which the first reactant is placed in a quartz tube, vacuumed and sealed, then fired and polished to obtain a second reactant, wherein the vacuum level for vacuuming and sealing is ≤ 50 Pa, and the firing is performed by raising the temperature from room temperature to 400-600°C over 30-120 minutes and maintaining the temperature for a predetermined time. Step 300 includes the step of heating the second reactant under the protection of an inert gas and passing a carbon-containing gas through it to obtain a sulfide solid electrolyte material, wherein the carbon-containing gas comprises at least one of CS2 or CCl4, and the flow rate of the carbon-containing gas is 1 to 20 L / min.

[0036] An electrolyte layer comprising the above-mentioned sulfide solid electrolyte material or a sulfide solid electrolyte material manufactured by the above-mentioned manufacturing method, wherein the electrolyte layer is formed by pressure molding the sulfide solid electrolyte material.

[0037] A lithium-ion battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode and the negative electrode, wherein the solid electrolyte layer comprises the sulfide solid electrolyte material, the sulfide solid electrolyte material produced by the above-mentioned manufacturing method, or the electrolyte layer. (Example 1)

[0038] In an inert gas glove box, the chemical formula is Li 5.54 P 0.96 C 0.04 S 4.4 O 0.1 Cl 1.5According to the mass ratio, 8.83 g of Li2S, 10.67 g of P2S5, 6.36 g of LiCl, and 0.3 g of Li2O powder raw materials were weighed out. These raw materials were uniformly polished and mixed in an agate mortar, then placed in a 250 ml sealed ball mill pot and uniformly ground into a fine powder using zirconia balls. The ball mill rotation speed was set to 300 rpm, and the ball milling process was carried out for 12 hours to obtain the first reaction product. The ground first reaction product was placed in a quartz tube, vacuumed and sealed, and the vacuum was maintained at 5 Pa. The sealed quartz tube was then placed in a muffle furnace and fired. The firing method involved raising the temperature from room temperature to 500°C over 60 minutes and maintaining that temperature for 15 hours. After that, the temperature was lowered to 50°C over 8 hours to obtain the second reaction product. After removing the second reactant from the quartz tube into the glove box, it was finely ground in an agate mortar. The resulting second reactant was then transferred to an atmospheric tubular furnace and heated to 300°C under the protection of an inert gas. Subsequently, CS2 gas was passed through the tubular furnace at a flow rate of 2 L / min. After maintaining the temperature for 10 minutes, the CS2 gas flow was stopped, and after normal cooling, it was removed and crushed to obtain Li 5.54 P 0.96 C 0.04 S 4.4 O 0.1 Cl 1.5 A solid electrolyte material was obtained, and Figure 1 shows Li in Example 1 provided by the present invention. 5.54 P 0.96 C 0.04 S 4.4 O 0.1 Cl 1.5 Figure 2 shows the X-ray diffraction spectrum of the electrolyte, and Figure 2 shows the Li in Example 1 provided by the present invention. 5.54 P 0.96 C 0.04 S 4.4 O 0.1 Cl 1.5 These are electrochemical impedance spectra of the electrolyte. As shown in Figures 1 and 2, the solid electrolyte material of this embodiment is free of impurity phases and exhibits relatively good electrochemical performance.

[0039] (Example 2) In an inert gas glove box, the chemical formula is Li 5.55 P0.95 C 0.05 S 4.3 O 0.2 Cl 1.5 According to the mass ratio, 8.4 g of Li2S, 10.56 g of P2S5, 6.36 g of LiCl, and 0.6 g of Li2O powder raw materials were weighed out. These raw materials were uniformly polished and mixed in an agate mortar, then placed in a 250 ml sealed ball mill pot and uniformly ground into a fine powder using zirconia balls. The ball mill rotation speed was set to 300 rpm, and the ball milling process was carried out for 12 hours to obtain the first reaction product. The ground first reaction product was placed in a quartz tube, vacuumed and sealed, and the vacuum was maintained at 1 Pa. The sealed quartz tube was then placed in a muffle furnace and fired. The firing method involved raising the temperature from room temperature to 600°C over 90 minutes and maintaining that temperature for 15 hours. After that, the temperature was lowered to 50°C over 8 hours to obtain the second reaction product. After removing the second reactant from the quartz tube into the glove box, it was finely ground in an agate mortar, and the resulting second reactant was transferred to an atmospheric tubular furnace. The second reactant was heated to 300°C under the protection of an inert gas, and then CS2 gas was passed through the tubular furnace at a flow rate of 10 L / min. After maintaining the temperature for 10 minutes, the flow of CS2 gas was stopped, and after normal cooling, it was removed and crushed to obtain Li 5.55 P 0.95 C 0.05 S 4.3 O 0.2 Cl 1.5 We obtained a solid electrolyte material.

[0040] (Example 3) In an inert gas glove box, the chemical formula is Li 5.51 P 0.99 C 0.01 S 4.44 O 0.06 Cl 1.5According to the mass ratio, 8.95 g of Li2S, 11 g of P2S5, 6.36 g of LiCl, and 0.18 g of Li2O powder raw materials were weighed out. These raw materials were uniformly polished and mixed in an agate mortar, then placed in a 250 ml sealed ball mill pot and uniformly ground into a fine powder using zirconia balls. The ball mill rotation speed was set to 300 rpm, and the ball milling process was carried out for 12 hours to obtain the first reaction product. The ground first reaction product was placed in a quartz tube, vacuumed and sealed, and the vacuum was maintained at 20 Pa. The sealed quartz tube was then placed in a muffle furnace and fired. The firing method involved raising the temperature from room temperature to 450°C over 120 minutes and maintaining that temperature for 15 hours. After that, the temperature was lowered to 50°C over 8 hours to obtain the second reaction product. After removing the second reactant from the quartz tube from the glove box, it was finely ground in an agate mortar, and the resulting second reactant was transferred to an atmospheric tubular furnace. The second reactant was heated to 300°C under the protection of an inert gas, and then CS2 gas was passed through the tubular furnace at a flow rate of 1 L / min. After maintaining the temperature for 10 minutes, the flow of CS2 gas was stopped, and after normal cooling, it was removed and crushed to obtain Li 5.51 P 0.99 C 0.01 S 4.44 O 0.06 Cl 1.5 We obtained a solid electrolyte material.

[0041] (Example 4) In an inert gas glove box, the chemical formula is Li 5.64 P 0.96 C 0.04 S 4.5 O 0.1 Cl 1.4Weigh 9.66 g of Li2S, 10.67 g of P2S5, 5.26 g of LiCl, and 0.30 g of Li2O powder raw materials according to the mass ratio, uniformly grind and mix the above raw materials in an agate mortar, then put them into a 250 ml sealed ball mill pot and uniformly pulverize them using zirconia balls. Set the rotation speed of the ball mill to 300 rpm and perform the ball mill treatment for 12 h to obtain the first reactant. Put the pulverized first reactant into a quartz tube, evacuate and seal it, maintain the vacuum degree at 50 Pa, then put the sealed quartz tube into a muffler furnace for firing. The firing adopts a method of heating from room temperature to 400 °C over 30 min and keeping the temperature at this temperature for 15 h, and then cooling down to 50 °C over 8 h to obtain the second reactant. After taking out the second reactant in the quartz tube from the glove box, finely pulverize it in an agate mortar, transfer the obtained second reactant to an atmospheric tubular furnace, heat the second reactant to 300 °C under the protection of an inert gas, then pass CCl4 gas through the tubular furnace for reaction. The ventilation flow rate of CCl4 gas is 20 L / min. After keeping the temperature for 10 min, stop the ventilation of CCl4 gas, cool it normally and then take it out, crush it, and obtain the solid electrolyte material of Li 5.64 P 0.96 C 0.04 S 4.5 O 0.1 Cl 1.4 .

[0042] (Examples 5 - 32) In an inert gas glove box, weigh Li2S, P2S5, LiCl, Li2O and other powder raw materials according to different mass ratios of the chemical formula Li a P b C m S d O n X f . Except that the measured amounts are different according to the ratios of the elements in the chemical formula, other synthesis conditions are the same as those in Example 1.

[0043] (Comparative Example 1) In an inert gas glove box, the chemical formula is Li 5.5 PS 4.5 Cl1.5 According to the mass ratio, 9.2 g of Li2S, 11.12 g of P2S5, and 6.36 g of LiCl powder raw materials were weighed, and the above raw materials were uniformly ground and mixed in an agate mortar. Then, they were put into a 250 ml sealed ball mill pot and uniformly pulverized using zirconia balls. The rotation speed of the ball mill was set to 300 rpm, and the ball mill treatment was performed for 12 h. The pulverized mixed powder was put into a quartz tube, evacuated and sealed, and the vacuum degree was maintained within 50 Pa. The sealed quartz tube was put into a muffler furnace and fired. The firing program adopted a method of heating from room temperature to 500 °C over 120 min and holding at that temperature for 15 h, and then cooling to 50 °C over 8 h. After taking out the sample in the quartz tube from the glove box, it was finely pulverized in an agate mortar, and Li 5.5 PS 4.5 Cl 1.5 solid electrolyte material was obtained.

[0044] (Comparative Example 2) In an inert gas glove box, according to the mass ratio of the chemical formula Li 5.5 PS 4.4 O 0.1 Cl 1.5 8.74 g of Li2S, 11.12 g of P2S5, 6.36 g of LiCl, and 0.3 g of Li2O powder raw materials were weighed. Other synthesis conditions were the same as those in Comparative Example 1. Finally, Li 5.5 PS 4.4 O 0.1 Cl 1.5 solid electrolyte material was obtained.

[0045] (Comparative Example 3) In an inert gas glove box, according to the chemical formula Li 5.54 P 0.96 C 0.04 S 4.42 Cl 1.5According to the mass ratio, 9.29 g of Li2S, 10.67 g of P2S5, and 6.36 g of LiCl powder raw materials were weighed out. These raw materials were uniformly polished and mixed in an agate mortar, then placed in a 250 ml sealed ball mill pot and uniformly ground into fine powder using zirconia balls. The ball mill rotation speed was set to 300 rpm, and the ball milling process was performed for 12 hours. The ground mixed powder was placed in a quartz tube, vacuumed and sealed, and the vacuum level was maintained within 50 Pa. The sealed quartz tube was then placed in a muffle furnace and fired. The firing program involved raising the temperature from room temperature to 500°C over 120 minutes, maintaining that temperature for 15 hours, and then cooling down to 50°C over 8 hours. After removing the sample from the glove box, it was finely ground in an agate mortar, and the resulting sample was transferred to an atmospheric tubular furnace. The sample was heated to 300°C under the protection of an inert gas, then CS2 gas was passed through the tubular furnace and the temperature was maintained for 10 minutes. After stopping the flow of CS2 gas and allowing it to cool normally, the sample was removed and crushed, and Li 5.54 P 0.96 C 0.04 S 4.42 Cl 1.5 We obtained a solid electrolyte material.

[0046] The following three methods are commonly used to measure sulfide electrolytes. 1. Measurement of ionic conductivity The electrolyte powder was pressurized in a mold cell at a pressure of 250 MPa, and the thickness of the electrolyte layer was measured and denoted as L. Subsequently, a symmetrical blocking electrode cell consisting of a steel column / electrolyte / steel column was assembled in the mold cell, and the AC impedance of the cell under open-circuit conditions was measured. The obtained impedance value was denoted as R, and the ion conductivity was calculated using the formula σ = L / (R·S), where σ is the ionic conductivity, L is the thickness of the electrolyte layer, R is the impedance value, and S is the electrode area of ​​the electrolyte sheet. The ionic conductivity measured at room temperature of 25°C is the ionic conductivity of the electrolyte powder. 2. Measurement of electronic conductivity A symmetrical barrier electrode battery was constructed using the same method as for measuring ionic conductivity. The average current was measured until equilibrium time at a voltage of 3.5V, and the obtained average current value was denoted as I. The current was then calculated using the formula λ = L / (S*V / I), where λ is the electronic conductivity, L is the thickness of the electrolyte layer, S is the pressure area of ​​the electrolyte layer, V is the equilibrium voltage of 3.5V, and I is the equilibrium current (average current value from 1700s to 1800s). The electronic conductivity measured at room temperature of 25°C is the electronic conductivity of the electrolyte powder. 3. Measurement of ionic conductivity maintenance rate: Ionic conductivity was measured by leaving an electrolyte powder with σ0 in a test box with a dew point of -45°C for 24 hours, and the ionic conductivity after standing was σ t And, σ t The ionic conductivity maintenance rate is denoted as / σ0 × 100%.

[0047] The chemical composition, ionic conductivity, electronic conductivity, ionic conductivity after 24 hours of standing at -45°C dew point, and ionic conductivity retention rate of the sulfide solid electrolytes of Examples 1-32 and Comparative Examples 1-3 are shown in Table 1.

[0048] JPEG2026515861000002.jpg163170JPEG2026515861000003.jpg210170

[0049] Measurement of the cyclic stability of solid electrolytes The solid electrolyte was placed in the inner chamber of a 10mm diameter circular battery mold, and a pressure of 300MPa was applied to the inner chamber and held for 90 seconds to form the solid electrolyte layer. Then, the solid electrolyte, NCM523 positive electrode, and conductive carbon black were weighed out and uniformly mixed in a ratio of 40:55:5 to form a positive electrode mixture. The inner chamber of the battery mold was opened, and the obtained positive electrode mixture was injected into one side of the pressed electrolyte layer. A pressure of 300MPa was applied to the inner chamber and held for 90 seconds to form the solid battery positive electrode layer. The inner chamber of the battery mold was further opened, and a lithium indium alloy sheet was attached to the other side of the electrolyte layer. A pressure of 150MPa was applied to the inner chamber and held for 90 seconds to form the solid battery negative electrode layer. Finally, an all-solid-state lithium secondary battery was formed.

[0050] Assembled all-solid-state battery packs were placed in a constant temperature chamber at 25°C, and the cycle performance of the batteries was measured. Under measurement conditions with a current density of 0.3°C, the charge / discharge performance of the first cycle and the cycle charge / discharge performance of the solid-state batteries were measured. During the measurement process, the voltage range was set to 1.9~3.7V (Li + Set to / Li).

[0051] After manufacturing all-solid-state batteries using the electrolytes synthesized in Examples 1-32 and Comparative Examples 1-3, the measurement results of the battery cycle performance are shown in Table 2.

[0052] JPEG2026515861000004.jpg201170JPEG2026515861000005.jpg149170

[0053] In summary, the sulfide solid electrolyte material obtained in this invention improves electrolyte and cathode stability through co-doping with O and C. The scientific mechanism is that trace amounts of O and C in the electrolyte form a stable Li2CO3 intermediate layer at the interface between the cathode and electrolyte particles during the battery cycle process. This intermediate layer prevents continuous oxidation of the sulfide electrolyte during the cycle process, thereby significantly improving cycle stability. Furthermore, it possesses high ionic conductivity, and when the O and C co-doping content in this embodiment is adopted, no impurity phase appears in the electrolyte's XRD spectrum, resulting in good cycle stability for the oxide cathode during charging and discharging of the solid-state battery. Its overall performance is clearly superior to conventional undoped or single-doped sulfide solid electrolytes. In addition, it has the characteristics of being easy to manufacture and capable of large-scale production, providing a good foundation for the large-scale application of solid electrolyte materials to all-solid-state batteries.

[0054] It should be understood that the above-described specific embodiments of the present invention are used solely for interpreting the principles of the present invention and do not limit the invention. Therefore, any modifications, equivalent substitutions, and improvements made without departing from the spirit and original scope of the invention should all be included within the scope of protection of the invention. Furthermore, the claims attached to the present invention are intended to encompass all changes and modifications that fall within the scope and boundaries of the claims, or within equivalent forms of such scope and boundaries.

[0055] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are for illustrative purposes only and do not limit the scope of the present invention. The scope of the present invention is limited by the appended claims and their equivalents. Those skilled in the art can make various substitutions and modifications without departing from the scope of the present invention, and all such substitutions and modifications should fall within the scope of the present invention.

[0056] While embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made to embodiments of the present invention without departing from the spirit and scope of the invention.

[0057] Clearly, the above embodiments are merely illustrative examples for clarity and do not limit the embodiments. Those skilled in the art can make other different forms of changes or variations based on the above description. It is neither necessary nor possible to cover all embodiments here. Obvious changes or variations derived therefrom are still within the scope of protection of the present invention.

Claims

1. The chemical formula is Li ａ P ｂ C ｍ S ｄ O ｎ Cl ｆ A sulfide solid electrolyte material characterized in that, where 5.4 ≤ a ≤ 6.1, 0.9 ≤ b ≤ 1, 0 < m ≤ 0.1, 4.1 ≤ d ≤ 5, 0 < n ≤ 0.3, and 1 ≤ f ≤ 1.

7.

2. The sulfide solid electrolyte material according to claim 1, characterized in that 0.01 ≤ m ≤ 0.05 and 0.05 ≤ n ≤ 0.

2.

3. The sulfide solid electrolyte material according to claim 1, characterized in that 5.4 ≤ a ≤ 5.6, 0.95 ≤ b ≤ 1, 4.3 ≤ d ≤ 4.6, and 1.4 ≤ f ≤ 1.

6.

4. The ionic conductivity of the sulfide solid electrolyte material is ≥ 5 × 10 －３ S / cm, electronic conductivity < 10 × 10 －９ The sulfide solid electrolyte material according to any one of claims 1 to 3, characterized in that the ionic conductivity retention rate after being left for 24 hours at S / cm and -45°C dew point is >50%.

5. A method for producing a sulfide solid electrolyte material according to any one of claims 1 to 4, Step 100 involves mixing raw materials for forming a sulfide solid electrolyte material and performing polishing mixing to obtain a first reactant, Step 200 involves placing the first reactant in a quartz tube, evacuating and sealing it, then firing and polishing it to obtain a second reactant. A manufacturing method characterized by comprising step 300, which involves heating the second reactant under the protection of an inert gas and passing a carbon-containing gas through it to obtain a sulfide solid electrolyte material.

6. The raw materials of the sulfide solid electrolyte material are Li ２ S, P ２ S ５ , LiCl and Li ２ O, and the manufacturing method according to claim 5, characterized by this.

7. Step 200, which involves placing the first reactant in a quartz tube, evacuating and sealing it, then firing and polishing it to obtain the second reactant, The vacuum level used for sealing by vacuuming is ≤ 50 Pa, The manufacturing method according to claim 5, characterized in that the firing method involves raising the temperature from room temperature to 400 to 600°C over 30 to 120 minutes and maintaining the temperature for a predetermined time.

8. The carbon-containing gas is at least CS ２ or CCl ４ The manufacturing method according to claim 5, characterized in that it includes one of the above, and the permeation flow rate of the carbon-containing gas is 1 to 20 L / min.

9. An electrolyte layer comprising a sulfide solid electrolyte material according to any one of claims 1 to 4 or a sulfide solid electrolyte material manufactured by a manufacturing method according to any one of claims 5 to 8, wherein the electrolyte layer is formed by pressure molding the sulfide solid electrolyte material.

10. A lithium-ion battery comprising a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode and the negative electrode, wherein the solid electrolyte layer comprises a sulfide solid electrolyte material according to any one of claims 1 to 4, a sulfide solid electrolyte material manufactured by the manufacturing method according to any one of claims 5 to 8, or the electrolyte layer according to claim 9.

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