A selenium-doped sulfide solid electrolyte, a preparation method and application thereof

Abstract

The application belongs to the technical field of solid electrolytes, and relates to a selenium-doped sulfide solid electrolyte and a preparation method and application thereof. 6± i P 1‑x M x S 5‑y Se y X, wherein 0<=i<1, 0<x<1, 0<y<1, M is one or more of Zr, Ta, Nb, Mo, Bi, In, Y, and X is one or more of Cl, Br and F. The application introduces selenium elements with larger ionic radius and lower electronegativity to replace sulfur elements, and introduces Zr, Ta, Nb, Mo, Bi, In or Y elements. The doped sulfide solid electrolyte system has excellent stability to air, organic solvents and lithium while ensuring high ionic conductivity, and the assembled full solid-state battery has excellent cycle stability.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid electrolytes and relates to a selenium-doped sulfide solid electrolyte and a preparation method and application thereof. Background Art

[0002] As a highly efficient secondary energy storage device, lithium-ion batteries offer advantages such as high specific power, low self-discharge, and no memory effect. They have been widely used in many fields, including mobile communications, rail transportation, and aerospace. The use of flammable electrolytes in commercial lithium-ion batteries currently poses significant safety risks. This is especially true when abnormal operating conditions such as short circuits, overcharging, and collisions occur. The temperature inside the battery can rise sharply, leading to safety issues such as thermal runaway, fire, and explosion, seriously threatening people's lives and property. Therefore, high energy density and high safety are pressing challenges for lithium-ion batteries, and the development of battery systems with even better performance is urgent.

[0003] All-solid-state lithium metal batteries (ALBs) have long been considered one of the most ideal next-generation energy storage devices due to their significant advantages in safety and energy density. As a key component of ALBs, solid electrolytes have garnered widespread attention due to their higher thermal stability and improved safety compared to liquid electrolytes. To date, a variety of solid electrolytes have been developed for material preparation, including sulfides, oxides, and polymer electrolytes. Sulfide solid electrolytes stand out due to their excellent ionic conductivity and good formability.

[0004] However, the application of sulfide solid electrolytes still faces the following challenges: (1) Poor air stability and solvent stability. According to the “soft and hard acid-base” theory, PS4 3- The structural center P is a hard acid. Compared with the soft acid S, it is more likely to react with the hard acid O in a humid environment, attacking the weak PS bond to produce toxic H2S gas, which poses a potential threat to the environment and operators. (2) Poor stability to lithium. Since the sulfide solid electrolyte is thermodynamically unstable to metallic lithium, it is easy to cause uneven lithium ion deposition during the battery cycle, forming lithium dendrites at the interface. When the lithium dendrites grow to a certain extent, they may pierce the solid electrolyte membrane, causing the battery to open or short-circuit and fail. Even if the lithium dendrites do not completely pierce the membrane, they may affect the battery's cycle stability due to factors such as local resistance changes, significantly shortening the battery's service life.

[0005] In order to meet the application requirements of all-solid-state lithium batteries, it is of great significance to develop a sulfide solid electrolyte with good air stability, solvent stability, electrochemical stability and high room temperature ionic conductivity to achieve high-performance batteries. Summary of the Invention

[0006] The present invention addresses the shortcomings of sulfide solid electrolytes in the prior art and provides a selenium-doped sulfide solid electrolyte, a preparation method, and an application thereof. The selenium-doped sulfide solid electrolyte not only ensures high ionic conductivity but also has excellent stability to air, organic solvents, and lithium, and the assembled all-solid-state battery exhibits excellent cycle stability.

[0007] The first object of the present invention is achieved through the following technical solutions:

[0008] A selenium-doped sulfide solid electrolyte with the general chemical formula Li 6±i P 1-x M x S 5-y Se y X, wherein 0≤i<1, 0<x<1, 0<y<1, M is one or more of Zr, Ta, Nb, Mo, Bi, In, and Y, and X is one or more of Cl, Br, and F. This is a sulfide solid electrolyte of the argyrodite phase.

[0009] Preferably, 0≤i≤0.8; more preferably, 0≤i≤0.5. i can be any value among 0, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0010] Preferably, 0.01≤x≤0.8, more preferably, 0.01≤x≤0.5. x can be any value of 0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0011] Preferably, 0.01≤y≤0.8, more preferably, 0.01≤y≤0.5. y can be any value of 0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, etc.

[0012] Preferably, 0≤i≤0.8, 0.01≤x≤0.8, 0.01≤y≤0.8.

[0013] Preferably, 0≤i≤0.5, 0.01≤x≤0.5, 0.01≤y≤0.5.

[0014] Preferably, M is one or more of Zr and Nb.

[0015] Preferably, M is Nb. When M is Nb, the obtained sulfide electrolyte has high room temperature ionic conductivity and better stability to air, organic solvents, and lithium.

[0016] Preferably, X is Cl.

[0017] Preferably, the room temperature ionic conductivity of the sulfide solid electrolyte is 3×10 -3 ~5×10 -2 S / cm. More preferably, 3×10 -3 ~1×10 -2 S / cm, and more preferably 3×10 -3 ~8×10 -3 S / cm.

[0018] Preferably, after the sulfide solid electrolyte is exposed to a dry room dew point temperature of -40°C for 60 minutes, the room temperature ionic conductivity retention rate is ≥85%, more preferably ≥87%.

[0019] Preferably, after the sulfide solid electrolyte is immersed in a benzene organic solvent, an ester organic solvent, an ether organic solvent, acetonitrile or tetrahydrofuran for 30 minutes, the room temperature ionic conductivity retention rate is ≥80%, more preferably ≥83%.

[0020] Preferably, metallic lithium is used as a symmetrical electrode and the sulfide solid electrolyte is used as an electrolyte layer to assemble a symmetrical battery. The symmetrical battery is cycle tested using a Blue Power CT2001A battery test system. The battery is measured at a current density of 0.1 mA cm -2 The lower stable cycle is ≥ 4000 hours, more preferably ≥ 5000 hours.

[0021] The second object of the present invention is achieved through the following technical solutions:

[0022] A method for preparing a selenium-doped sulfide solid electrolyte comprises the following steps:

[0023] (1) According to the general formula Li 6±i P 1-x M x S 5-y Se y X, Li2S, P2S5, LiX, selenium source and metal M source in stoichiometric ratios are weighed and physically mixed to obtain precursor powder;

[0024] (2) The precursor powder is calcined and naturally cooled to room temperature to obtain a selenium-doped argyrodite-phase sulfide solid electrolyte.

[0025] Preferably, the LiX is one or more of LiCl, LiBr, and LiF.

[0026] Preferably, the selenium source and metal M source are Se powder, P powder and M a Ab , wherein M is one or more of Zr, Ta, Nb, Mo, Bi, In, and Y, A is one or more of S, Cl, Br, and F, a=1 to 2, and b=2 to 5. More preferably, M a A b It can be one or more of ZrS2, ZrCl4, TaCl5, TaS2, NbCl5, NbS2, MoCl5, MoS2, Bi2S5, BiCl3, In2S3, and YCl3. When Se is added as a single substance, P powder needs to be added to react with Se to promote the redox reaction. Without P powder, Se cannot be effectively doped.

[0027] Preferably, the selenium source and the metal M source are M c Se d , wherein M is one or more of Zr, Ta, Nb, Mo, Bi, In, and Y, c=1-2, d=2-5. More preferably, M c Se d It is one or more of ZrSe2, Ta2Se5, Nb2Se5, Mo2Se5, Bi2Se5, In2Se3, and Y2Se3.

[0028] Preferably, the physical mixing is mechanical mixing, including high-energy ball milling, mechanical stirring, mechanical shaking, grinding or roller milling, and the mixing time is 20 minutes to 48 hours.

[0029] Preferably, the calcination treatment is carried out in an inert atmosphere, with a heating rate of 1-5°C / min, a calcination temperature of 500-600°C, and a calcination time of 0.5-24 hours.

[0030] The third object of the present invention is achieved through the following technical solutions:

[0031] An all-solid-state lithium secondary battery comprises a positive electrode, a negative electrode and the above-mentioned selenium-doped argyrodite phase sulfide solid electrolyte.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. Use elements with larger radius and lower electronegativity than S element to replace S element to improve air stability and solvent stability. However, the ionic radius of the S-substituent element must be controlled within a certain range, otherwise it will be difficult to enter PS4. 3-Tetrahedron exists in the lattice in a free form, resulting in the generation of by-products and reducing structural stability. After research, it was found that the present invention can produce excellent results by introducing selenium with a larger ionic radius (~103 pm) and lower electronegativity (2.55) to replace sulfur with a smaller ionic radius (~88 pm) and higher electronegativity (2.58). Specifically, the replacement of sulfur with selenium can increase the unit cell volume, broaden the ion transmission channel inside the lithium electrolyte, and thus increase Li + The ion transfer rate makes the prepared sulfide solid electrolyte have high ionic conductivity. The substitution of selenium for sulfur weakens the Coulomb attraction in the lattice, forming a more stable crystal structure and improving the chemical stability of the sulfide solid electrolyte - air stability and solvent stability.

[0034] 2. The present invention introduces metal M cations to form Li + Alloys with low diffusion energy barriers and metal alloys can promote the uniform deposition of lithium metal at the interface, thereby preventing the growth of lithium dendrites and improving lithium stability.

[0035] 3. The present invention uses Se to replace the S element and introduces metal M cations to prepare a new selenium-doped argyrodite-phase sulfide solid electrolyte. After being exposed to a dry room dew point temperature of -40°C for 60 minutes, the room temperature ionic conductivity retention rate reaches more than 85%, indicating that it has excellent air stability. After being immersed in benzene, ester, ether, acetonitrile, and tetrahydrofuran organic solutions for 30 minutes, the room temperature ionic conductivity retention rate all reaches more than 80%, indicating that it has excellent solvent stabilizer. A lithium battery is prepared by attaching lithium sheets on both sides of the sulfide solid electrolyte. At a current density of 0.1 mA cm -2 It can be stably cycled for more than 4000 hours under high temperature, indicating that it has excellent stability to lithium.

[0036] 4. Since the sulfide solid electrolyte of the present invention has high air stability, solvent stability and electrochemical stability, the all-solid-state lithium secondary battery prepared using the sulfide solid electrolyte has good long-cycle stability and exhibits excellent cycle stability.

[0037] 5. When Se replaces the S element and the Nb element is introduced, the prepared argyrodite-phase sulfide solid electrolyte has better air stability, solvent stability and electrochemical stability, and the all-solid-state lithium secondary battery prepared therefrom has better cycle stability.

[0038] 6. The preparation method of the sulfide solid electrolyte of the present invention is simple to operate. Li2S, P2S5, LiX, a selenium source, and a metal M source are weighed in a stoichiometric ratio according to the general formula and physically mixed to obtain a precursor powder. After further high-temperature calcination, the product is naturally cooled to room temperature. This method is highly practical and suitable for large-scale production.

[0039] 7. In the preparation process of the sulfide solid electrolyte of the present invention, when Se is added in the form of a single substance, P powder is creatively added to react with Se to undergo oxidation-reduction reaction to promote the reaction. The selenium source and metal M source are Se powder, P powder and M a A b The performance of the sulfide solid electrolyte prepared when the selenium source is M c Se d . BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Li6P in Example 6 of the present invention 0.95 Nb 0.05 S 4.9 Se 0.1 AC impedance spectroscopy of the Cl sulfide solid electrolyte and the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1;

[0041] Figure 2 Li6P in Example 6 of the present invention 0.95 Nb 0.05 S 4.9 Se 0.1 Lithium / / lithium symmetric battery cycling curves of Cl sulfide solid electrolyte and Li6PS5Cl sulfide solid electrolyte in Comparative Example 1;

[0042] Figure 3 Li6P in Example 6 of the present invention 0.95 Nb 0.05 S 4.9 Se 0.1 Long cycle diagram of all-solid-state battery at 1C rate of Cl sulfide solid electrolyte and Li6PS5Cl sulfide solid electrolyte in Comparative Example 1. DETAILED DESCRIPTION

[0043] Below by specific embodiment and accompanying drawing, technical scheme of the present invention is further described explanation, it should be understood that specific embodiment described herein is only for helping to understand the present invention, is not used for specific limitation of the present invention.And accompanying drawing used herein, is only for better illustrating the disclosure of the present invention, does not have limiting effect on protection scope.If no special instructions, the raw materials adopted in the embodiment of the present invention are all raw materials commonly used in this area, and the method adopted in the embodiment is all conventional method in this area.

[0044] In the following examples and comparative examples, the room temperature is approximately 25°C.

[0045] Example 1

[0046] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0047] Li2S, P2S5, LiCl, In2S3, Se and P with purity above 99% were weighed in stoichiometric ratio in an agate mortar under argon atmosphere and ground for 30 minutes under the condition of water content less than 10 ppm to obtain Li 6.1 P 0.95 In 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0048] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li 6.1 P 0.95 In 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0049] Performance testing and battery assembly

[0050] The ground Li 6.1 P 0.95 In 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 4.3×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 48.3%; after exposure to the dew point temperature of the air in the dry room (dry room dew point temperature) of -60℃, -50℃, and -40℃ for 60 minutes, the room temperature conductivity is 4.1×10 -3 S cm -1 , 4.01×10 -3 S cm -1 , 3.9×10 -3 S cm -1 , the retention rates were 95.3%, 93.3% and 90.7% respectively; 6.1 P 0.95 In 0.05 S 4.9 Se 0.1After the Cl sulfide solid electrolyte was immersed in toluene, butyl butyrate, ether, acetonitrile, and tetrahydrofuran for 30 min, the room temperature ionic conductivity was 3.7×10 -3 S cm -1 , 3.71×10 -3 S cm -1 , 3.66×10 -3 S cm -1 , 3.62×10 -3 S cm -1 , 3.64×10 -3 S cm -1 The retention rates were 86%, 86.3%, 85.1%, 84.2% and 84.7% respectively.

[0051] With metallic lithium as the symmetrical electrode, Li 6.1 P 0.95 In 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can circulate stably for 5100 hours.

[0052] Li 6.1 P 0.95 In 0.05 S 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged over a voltage range of 3.0 to 4.2 V at a constant rate of 1C. After 300 cycles, the capacity retention rate was 87.1%.

[0053] Example 2

[0054] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0055] Li2S, P2S5, LiCl, YCl3, Se and P with purity above 99% were weighed in stoichiometric ratio in an argon atmosphere and placed in an agate mortar. Li2S was ground for 30 minutes under the condition of water content less than 10 ppm. 6.1 P 0.95 Y 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0056] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li 6.1 P 0.95 Y 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0057] Performance testing and battery assembly

[0058] The ground Li 6.1 P 0.95 Y 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 3.76×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 29.7%; after exposure to the dry room dew point temperature of -60℃, -50℃, and -40℃ for 60min, the room temperature conductivity is 3.51×10 -3 S cm -1 , 3.41×10 -3 S cm -1 , 3.29×10 -3 S cm -1 , the retention rates were 93.4%, 90.7% and 87.5% respectively; 6.1 P 0.95 Y 0.05 S 4.9 Se 0.1 After the Cl sulfide solid electrolyte was immersed in toluene, butyl butyrate, ether, acetonitrile, and tetrahydrofuran for 30 min, the room temperature ionic conductivity was 3.2×10 -3 S cm -1 , 3.15×10 -3 S cm -1 , 3.16×10 -3 S cm -1 , 3.12×10 -3 S cm -1 , 3.14×10 -3 S cm -1 The retention rates were 85.1%, 83.8%, 84%, 83% and 83.5% respectively.

[0059] With metallic lithium as the symmetrical electrode, Li 6.1 P 0.95 Y 0.05 S4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 7800 hours.

[0060] Li 6.1 P 0.95 Y 0.05 S 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 83.5%.

[0061] Example 3

[0062] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0063] Li2S, P2S5, LiCl, ZrS2, Se and P with purity above 99% were weighed in stoichiometric ratio in an argon atmosphere and placed in an agate mortar. Li2S was ground for 30 minutes under the condition of water content less than 10 ppm. 6.05 P 0.95 Zr 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0064] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li 6.05 P 0.95 Zr 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte;

[0065] Performance testing and battery assembly

[0066] The ground Li 6.05 P 0.95 Zr 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 3.91×10 -3 S cm -1Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 34.8%; after exposure to the dry room dew point temperature of -60℃, -50℃, and -40℃ for 60min, the room temperature conductivity is 3.72×10 -3 S cm -1 , 3.65×10 -3 S cm -1 , 3.57×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 3.42×10 -3 S cm -1 , 3.44×10 -3 S cm -1 , 3.36×10 -3 S cm -1 , 3.37×10 -3 Scm -1 , 3.39×10 -3 S cm -1 The retention rates were 87.5%, 88%, 85.9%, 86.2% and 86.7% respectively.

[0067] With metallic lithium as the symmetrical electrode, Li 6.05 P 0.95 Zr 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can stably cycle for 7300 hours;

[0068] Li 6.05 P 0.95 Zr 0.05 S 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 91.2%.

[0069] Example 4

[0070] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0071] Li2S, P2S5, LiCl, TaCl5, Se and P with purity above 99% were weighed in stoichiometric ratio in an agate mortar under argon atmosphere and ground for 30 minutes under the condition of water content less than 10 ppm to obtain Li6P 0.95 Ta 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0072] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Ta 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte;

[0073] Performance testing and battery assembly

[0074] The ground Li6P 0.95 Ta 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 4.23×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 45.9%; after exposure to the dry room dew point temperature of -60℃, -50℃, and -40℃ for 60min, the room temperature conductivity is 3.95×10 -3 S cm -1 , 3.87×10 -3 S cm -1 , 3.82×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 3.69×10 -3 S cm -1 , 3.68×10 -3 S cm -1 , 3.72×10 -3 S cm -1 , 3.6×10 -3 S cm -1 , 3.58×10 -3 S cm -1The retention rates were 87.2%, 87%, 87.9%, 85.1% and 84.6% respectively.

[0075] With metallic lithium as the symmetrical electrode, Li6P 0.95 Ta 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 6800 hours.

[0076] Li6P 0.95 Ta 0.05 S 4.9 Se 0.1 The all-solid-state battery is assembled with a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. Charge and discharge voltages ranged from 3.0 to 4.2 V, at a constant rate of 1C, and after 300 cycles, the capacity retention rate was 88.1%.

[0077] Example 5

[0078] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0079] Li2S, P2S5, LiCl, and Nb2Se5 with a purity of more than 99% were weighed in an argon atmosphere according to the stoichiometric ratio and placed in an agate mortar. Li6P was obtained after grinding for 30 minutes under the condition of water content less than 10 ppm. 0.95 Nb 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0080] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0081] Performance testing and battery assembly

[0082] The ground Li6P 0.95 Nb 0.05 S 4.9 Se 0.1The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 5.26×10 -3 S cm -1 After being exposed to the dew point temperature of -60℃, -50℃ and -40℃ in the dry room for 60min, the room temperature conductivity was 5.03×10 -3 S cm -1 , 4.91×10 -3 S cm -1 , 4.82×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 4.64×10 -3 S cm -1 , 4.65×10 -3 S cm -1 , 4.68×10 -3 S cm -1 , 4.69×10 -3 S cm -1 , 4.58×10 -3 S cm -1 The retention rates were 88.2%, 88.4%, 88.9%, 89.1% and 87.1% respectively.

[0083] With metallic lithium as the symmetrical electrode, Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 8100 hours.

[0084] Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 91.5%.

[0085] Example 6

[0086] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0087] Li2S, P2S5, LiCl, NbCl5, Se and P with purity above 99% were weighed in stoichiometric ratio in an argon atmosphere and placed in an agate mortar. Li6P was obtained after grinding for 30 minutes under the condition of water content less than 10 ppm. 0.95 Nb 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0088] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0089] Performance testing and battery assembly

[0090] The ground Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 5.38×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity of the electrolyte is increased by 85.5%; after exposure to the dew point temperature of -60℃, -50℃ and -40℃ for 60min, the room temperature conductivity is 5.16×10 -3 S cm -1 , 5.04×10 -3 S cm -1 , 4.95×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 4.8×10 -3 S cm -1 , 4.83×10 -3 S cm -1 , 4.86×10 -3 S cm -1 , 4.82×10 -3 S cm -1 , 4.89×10 -3 S cm -1The retention rates were 89.2%, 89.8%, 90.3%, 89.6% and 90.9% respectively; the conductivity after exposure at -40℃ and immersion in acetonitrile solution was compared with the ionic conductivity of Li6PS5Cl sulfide solid electrolyte in Comparative Example 1. Figure 1 shown.

[0091] With metallic lithium as the symmetrical electrode, Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can be stably cycled for 8300 hours under the same conditions, showing excellent stability to lithium compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1 (see Figure 2 ).

[0092] Li6P 0.95 Nb 0.05 S 4.9 Se 0.1 A solid-state battery was assembled with a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. The battery was electrochemically tested using a Blue Power CT2001A battery test system. The charge and discharge voltage range was 3.0-4.2 V, the rate was 1C, and constant rate charge and discharge were performed. After 300 cycles, the capacity retention rate was 92.4%. Figure 3 As shown, the capacity retention rate of the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1 is only 76.6% after 300 cycles at a rate of 1C.

[0093] Example 7

[0094] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0095] Li2S, P2S5, LiCl, MoCl5, Se and P with purity above 99% were weighed in stoichiometric ratio in an agate mortar under argon atmosphere and ground for 30 minutes under the condition of water content less than 10 ppm to obtain Li6P 0.95 Mo 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0096] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Mo 0.05 S4.9 Se 0.1 Cl sulfide solid electrolyte.

[0097] Performance testing and battery assembly

[0098] The ground Li6P 0.95 Mo 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 4.43×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 52.8%; after exposure to the dry room dew point temperature of -60℃, -50℃, and -40℃ for 60min, the room temperature conductivity is 4.2×10 -3 S cm -1 , 4.12×10 -3 S cm -1 , 4.05×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 3.99×10 -3 S cm -1 , 3.92×10 -3 S cm -1 , 3.96×10 -3 S cm -1 , 3.82×10 -3 S cm -1 , 3.86×10 -3 S cm -1 The retention rates were 90.1%, 88.5%, 89.4%, 86.2% and 87.1% respectively.

[0099] With metallic lithium as the symmetrical electrode, Li6P 0.95 Mo 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 6800 hours.

[0100] Li6P 0.95 Mo 0.05 S 4.9 Se 0.1An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 85.4%.

[0101] Example 8

[0102] The sulfide solid electrolyte of this embodiment is prepared by the following method:

[0103] Li2S, P2S5, LiCl, Bi2S5, Se and P with purity above 99% were weighed in stoichiometric ratio in an agate mortar under argon atmosphere and ground for 30 minutes under the condition of water content less than 10 ppm to obtain Li6P 0.95 Bi 0.05 S 4.9 Se 0.1 Cl precursor powder;

[0104] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Bi 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0105] Performance testing and battery assembly

[0106] The ground Li6P 0.95 Bi 0.05 S 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 3.98×10 -3 S cm -1 Compared with the Li6PS5Cl sulfide solid electrolyte in Comparative Example 1, the ionic conductivity is increased by 37.2%; after exposure to the dry room dew point temperature of -60℃, -50℃, and -40℃ for 60min, the room temperature conductivity is 3.8×10 -3 S cm -1 , 3.7×10 -3 S cm -1 , 3.62×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 3.5×10-3 S cm -1 , 3.45×10 -3 S cm -1 , 3.46×10 -3 S cm -1 , 3.42×10 -3 S cm -1 , 3.46×10 -3 S cm -1 The retention rates were 87.9%, 86.7%, 86.9%, 85.9% and 86.9% respectively.

[0107] With metallic lithium as the symmetrical electrode, Li6P 0.95 Bi 0.05 S 4.9 Se 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 5300 hours.

[0108] Li6P 0.95 Bi 0.05 S 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 85.1%.

[0109] Comparative Example 1

[0110] The sulfide solid electrolyte of Comparative Example 1 was prepared by the following method:

[0111] Under argon atmosphere, Li2S, P2S5, and LiCl with a purity of more than 99% were weighed according to the stoichiometric ratio and placed in an agate mortar. After grinding for 30 minutes under the condition of water content less than 10 ppm, the Li6PS5Cl precursor powder was obtained.

[0112] The precursor powder was placed in an inert atmosphere (argon) and sintered at 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. It was finally cooled to room temperature and ground evenly to obtain Li6PS5Cl sulfide solid electrolyte.

[0113] Performance testing and battery assembly

[0114] The ground Li6PS5Cl sulfide solid electrolyte powder was pressed into a tablet and its room temperature ionic conductivity was tested to be 2.9×10 -3 S cm -1 After being exposed to the dew point temperature of -60℃, -50℃ and -40℃ in the dry room for 60min, the room temperature conductivity was 2.47×10 -3 S cm -1 , 2.39×10 -3 S cm -1 , 2.32×10 -3 S cm -1 , the ionic conductivity retention rates were 85.2%, 82.4%, and 80.1%, respectively. After the sulfide solid electrolyte was immersed in toluene, butyl butyrate, ether, acetonitrile, and tetrahydrofuran for 30 min, the room temperature ionic conductivity was 2.07×10 -3 S cm -1 , 2.02×10 -3 S cm -1 , 2.01×10 -3 S cm -1 , 2.05×10 -3 S cm -1 , 2×10 -3 S cm -1 , the retention rates were 71.4%, 69.7%, 69.3%, 70.7% and 69% respectively;

[0115] A symmetrical battery was assembled with lithium metal as the symmetrical electrode and Li6PS5Cl sulfide solid electrolyte as the electrolyte layer. Cyclic testing was performed using a Blue Power CT2001A battery test system. The battery was tested at a current density of 0.1 mA cm -2 It can cycle for 1700 hours.

[0116] An all-solid-state battery was assembled using a Li6PS5Cl sulfide solid electrolyte, a LiCoO2 cathode, and a lithium metal anode. Electrochemical performance was tested using a Blue Power CT2001A battery test system. Charge and discharge voltages ranged from 3.0 to 4.2 V, at a constant rate of 1C, and after 300 cycles, the battery maintained a capacity of 76.6%.

[0117] Comparative Example 2

[0118] The sulfide solid electrolyte of Comparative Example 2 was prepared by the following method:

[0119] Li2S, P2S5, LiCl, and NbCl5 with a purity of more than 99% were weighed in an argon atmosphere according to the stoichiometric ratio and placed in an agate mortar. Li6P was obtained after grinding for 30 minutes under the condition of water content less than 10 ppm.0.95 Nb 0.05 S5Cl precursor powder;

[0120] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Nb 0.05 S5Cl sulfide solid electrolyte.

[0121] Performance testing and battery assembly

[0122] The ground Li6P 0.95 Nb 0.05 S5Cl sulfide solid electrolyte powder was pressed into tablets, and its room temperature ionic conductivity was tested to be 3.41×10 -3 S cm -1 After being exposed to the dew point temperature of -60℃, -50℃ and -40℃ for 60min, the room temperature conductivity was 3.03×10 -3 S cm -1 , 2.93×10 -3 S cm -1 , 2.81×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 2.75×10 -3 S cm -1 , 2.76×10 -3 S cm -1 , 2.71×10 -3 S cm -1 , 2.7×10 -3 S cm -1 , 2.73×10 -3 S cm -1 The retention rates were 80.6%, 80.9%, 79.5%, 79.2% and 80.1% respectively.

[0123] With metallic lithium as the symmetrical electrode, Li6P 0.95 Nb 0.05 The S5Cl sulfide solid electrolyte was used as the electrolyte layer and assembled into a symmetrical battery. The battery was cycled using a Blue Power CT2001A battery test system at a current density of 0.1 mA cm -2 It can circulate stably for 3100 hours.

[0124] Li6P 0.95Nb 0.05 An all-solid-state battery was assembled using an S5Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 82.1%.

[0125] Comparative Example 3

[0126] The sulfide solid electrolyte of Comparative Example 3 was prepared by the following method:

[0127] Li2S, P2S5, LiCl, Se and P with a purity of more than 99% were weighed in an agate mortar according to the stoichiometric ratio under an argon atmosphere and ground for 30 minutes under the condition of water content less than 10 ppm to obtain Li6PS. 4.9 Se 0.1 Cl precursor powder;

[0128] The precursor powder was placed in an inert atmosphere (argon) and sintered at 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 h. Finally, it was naturally cooled to room temperature and ground to obtain Li6PS. 4.9 Se 0.1 Cl sulfide solid electrolyte.

[0129] Performance testing and battery assembly

[0130] The ground Li6PS 4.9 Se 0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 3.32×10 -3 S cm -1 After exposure to the dew point temperature of -60℃, -50℃ and -40℃ for 60min, the room temperature conductivity was 3.01×10 -3 S cm -1 , 2.92×10 -3 S cm -1 , 2.83×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 2.73×10 -3 S cm -1 , 2.71×10 -3 S cm -1 , 2.74×10 -3 S cm-1 , 2.75×10 -3 S cm -1 , 2.73×10 -3 S cm -1 The retention rates were 82.2%, 81.6%, 82.5%, 82.8% and 82.2% respectively.

[0131] With metallic lithium as the symmetrical electrode, Li6PS 4.9 Se 0.1 Cl sulfide solid electrolyte was used as the electrolyte layer, and the battery was assembled into a symmetrical battery. The battery was cycled using a Blue Power CT2001A battery test system. The battery was tested at a current density of 0.1 mA cm -2 It can cycle stably for 3500 hours.

[0132] Li6PS 4.9 Se 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 83.5%.

[0133] Comparative Example 4

[0134] The sulfide solid electrolyte of Comparative Example 4 was prepared by the following method:

[0135] Li2S, P2S5, LiCl, NbCl5, Te and P with purity above 99% were weighed in stoichiometric ratio in an argon atmosphere and placed in an agate mortar. Li6P was obtained after grinding for 30 minutes under the condition of water content less than 10 ppm. 0.95 Nb 0.05 S 4.9 Te 0.1 Cl precursor powder;

[0136] The precursor powder was placed in an inert atmosphere (argon) and heated to 550 °C in a muffle furnace at a heating rate of 4 °C / min for 4 hours. Finally, it was naturally cooled to room temperature and ground to obtain Li6P 0.95 Nb 0.05 S 4.9 Te 0.1 Cl sulfide solid electrolyte.

[0137] Performance testing and battery assembly

[0138] The ground Li6P 0.95 Nb 0.05 S 4.9 Te0.1 The Cl sulfide solid electrolyte powder was pressed into a pellet and its room temperature ionic conductivity was tested to be 3.17×10 -3 S cm -1 After exposure to the dew point temperature of -60℃, -50℃ and -40℃ for 60min, the room temperature conductivity was 2.7×10 -3 S cm -1 , 2.59×10 -3 S cm -1 , 2.48×10 -3 S cm -1 The room temperature ionic conductivity of the sulfide solid electrolyte was 2.3×10 -3 S cm -1 , 2.32×10 -3 S cm -1 , 2.29×10 -3 S cm -1 , 2.34×10 -3 S cm -1 , 2.28×10 -3 S cm -1 The retention rates were 72.6%, 73.2%, 72.2%, 73.8% and 71.9% respectively.

[0139] With metallic lithium as the symmetrical electrode, Li6P 0.95 Nb 0.05 S 4.9 Te 0.1 Cl sulfide solid electrolyte is used as the electrolyte layer, and the battery is assembled into a symmetrical battery and cycle tested using a Blue Power CT2001A battery test system. The battery is tested at a current density of 0.1 mA cm -2 It can cycle stably for 1600 hours.

[0140] Li6P 0.95 Nb 0.05 S 4.9 Te 0.1 An all-solid-state battery was assembled using a Cl sulfide solid electrolyte, a LiCoO2 positive electrode, and a metallic lithium negative electrode. Electrochemical performance testing was performed using a Blue Power CT2001A battery test system. The battery was charged and discharged at a constant rate of 1C over a voltage range of 3.0 to 4.2 V. After 300 cycles, the capacity retention rate was 75.4%.

[0141] The various aspects, embodiments, and features of the present invention should be considered in all respects as illustrative and not limiting, the scope of which is defined solely by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

[0142] In the preparation method of the present invention, the order of the steps is not limited to the order listed. Persons skilled in the art will appreciate that varying the order of the steps without inventive effort is within the scope of the present invention. Furthermore, two or more steps or actions may be performed simultaneously.

[0143] Finally, it should be noted that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit its implementation. Persons skilled in the art may make various modifications, additions, or substitute similar methods for the described specific embodiments. It is not necessary and impossible to provide comprehensive examples of all implementations here. However, obvious variations or modifications arising from the essential spirit of the present invention remain within the scope of protection of the present invention, and interpreting them as any additional limitations would be contrary to the spirit of the present invention.

Claims

1. A selenium-doped sulfide solid electrolyte, characterized in that: Its chemical formula is Li 6±i P 1-x M x S 5-y Se y X, wherein 0≤i≤0.5, 0.01≤x≤0.5, 0.01≤y≤0.5, M is Nb, and X is one or more of Cl, Br, and F.

2. The selenium-doped sulfide solid electrolyte according to claim 1, characterized in that: The room temperature ionic conductivity of the sulfide solid electrolyte is 3×10 -3 ~5×10 -2 S / cm.

3. The selenium-doped sulfide solid electrolyte according to claim 1, characterized in that: After the sulfide solid electrolyte is exposed to a dry room dew point temperature of -40°C for 60 minutes, the room temperature ionic conductivity retention rate is ≥85%; After the sulfide solid electrolyte is immersed in a benzene organic solvent, an ester organic solvent, an ether organic solvent, acetonitrile or tetrahydrofuran for 30 minutes, the room temperature ionic conductivity retention rate is ≥80%.

4. The selenium-doped sulfide solid electrolyte according to claim 1, wherein: A symmetrical battery was assembled with metallic lithium as the symmetrical electrode and the sulfide solid electrolyte as the electrolyte layer. The symmetrical battery was cycle tested using a Blue Power CT2001A battery test system. The battery was measured to have a current density of 0.1 mA cm -2 The stable cycle is ≥4000 hours.

5. The method for preparing a selenium-doped sulfide solid electrolyte according to claim 1, wherein: The following steps are involved: (1) According to the general formula Li 6±i P 1-x M x S 5-y Se y X, Li2S, P2S5, LiX, selenium source and metal M source in stoichiometric ratios are weighed and physically mixed to obtain precursor powder; (2) The precursor powder is calcined and naturally cooled to room temperature to obtain a selenium-doped sulfide solid electrolyte.

6. The preparation method according to claim 5, characterized in that The selenium source and metal M source are Se powder, P powder and M a A b ; Or, the selenium source and the metal M source are M c Se d ; Wherein, M is Nb, A is one or more of S, Cl, Br, and F, a=1~2, b=2~5, c=1~2, and d=2~5.

7. The preparation method according to claim 6, characterized in that M a A b NbCl5; M c Se d It is Nb2Se5.

8. The preparation method according to claim 5, characterized in that The physical mixing is mechanical mixing, including high-energy ball milling, mechanical stirring, mechanical shaking, grinding or roller milling, and the mixing time is 20 minutes to 48 hours.

9. The preparation method according to claim 5, characterized in that The calcination treatment is carried out in an inert atmosphere, with a heating rate of 1-5°C / min, a calcination temperature of 500-600°C, and a calcination time of 0.5-24 hours.

10. An all-solid-state lithium secondary battery, characterized in that: The invention comprises a positive electrode, a negative electrode and the selenium-doped sulfide solid electrolyte according to claim 1.

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