Sulfide solid electrolyte and all-solid-state lithium battery

Abstract

The invention relates to the technical field of electrochemistry, and provides a sulfide solid-state electrolyte and an all-solid-state lithium battery, the chemical formula of the sulfide solid-state electrolyte is Li < 7 + x-y > P < 1-x > M < x > S6-2x-y > O < 2x > X < y >, M is at least one of variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of halogens, 0.002 < = x < = 0.3, 0.5 < = y < = 1.4, the molar ratio of the element M to the element O is 1: 2, and the molar ratio of the element O to the M is 1: 2. The unit cell parameters of the sulfide solid electrolyte meet the following conditions: a = b = c = 9.85-10, and the ionic conductivity of the sulfide solid electrolyte is greater than 8mS / cm. Through the arrangement, the sulfide solid electrolyte disclosed by the invention has good structural stability and oxidation-reduction resistance, and also has good air stability and ionic conductivity, so that longer cycle life and stronger voltage resistance of the all-solid-state lithium battery are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemistry, and in particular to a sulfide solid-state electrolyte and a full-solid-state lithium battery. BACKGROUND

[0002] Sulfide solid-state electrolytes are considered as one of the core materials for the next generation of full-solid-state lithium batteries due to their excellent ionic conductivity and flexible mechanical properties. However, sulfide solid-state electrolytes often exhibit problems such as structural instability and high interfacial reactivity during battery charge-discharge cycling, especially when used with high-voltage positive electrode materials and lithium metal, which easily leads to electrolyte oxidation or reduction decomposition, active sulfur element migration or skeleton structure disintegration, ultimately resulting in battery capacity attenuation and shortened life. The above problems are mainly attributed to the insufficient chemical stability of the [PS4] 3- tetrahedral units in high electrochemical stress environments, and the coordination environment composed of phosphorus (P 5+ ) and sulfur (S 2- ) in the skeleton is easily deteriorated by external disturbances. Current common stabilization strategies mainly focus on interface coating or lithium site substitution, which is difficult to fundamentally improve the skeleton stability of the electrolyte from the structure level. In addition, sulfide solid-state electrolytes are extremely susceptible to decomposition in air and will generate harmful gases such as hydrogen sulfide when in contact with moisture or oxygen, accompanied by significant structural damage and electrochemical performance decline. This air stability defect greatly limits the reliability of sulfide solid-state electrolytes in industrial production, storage and transportation, and actual applications.

[0003] Therefore, it is urgent to develop new doping design methods to enhance the structural stability and anti-oxidation-reduction ability of sulfide solid-state electrolytes from the inside of the crystal framework, while improving the air stability of sulfide solid-state electrolytes, so as to realize longer cycle life and stronger voltage resistance performance of full-solid-state lithium batteries. SUMMARY

[0004] The purpose of the present application is to provide a sulfide solid-state electrolyte and a full-solid-state lithium battery to enhance the structural stability and anti-oxidation-reduction ability of the sulfide solid-state electrolyte, while improving the air stability and ionic conductivity of the sulfide solid-state electrolyte, so as to realize longer cycle life and stronger voltage resistance performance of the full-solid-state lithium battery. The specific technical solutions are as follows:

[0005] The first aspect of the present application provides a sulfide solid-state electrolyte with a chemical formula of Li 7+x-y P 1-x M x S 6-2x- y O 2x X y, M is at least one of variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of halogen, 0.002≤x≤0.3, 0.5≤y≤1.4, the molar ratio of M element to O element is 1:2; the unit cell parameter of the sulfide solid electrolyte satisfies: a=b=c=9.85~10Å, the ionic conductivity of the sulfide solid electrolyte is >8mS / cm.

[0006] In an embodiment of the present application, 0.02≤x≤0.1, 1.25≤y≤1.4.

[0007] In an embodiment of the present application, X is at least one of Cl, Br and I.

[0008] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x M x S 6-2x-y O 2x X’ 0.7y X’’ 0.3y , X' or X'' is independently Cl, Br or I, and X' is different from X''.

[0009] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x M x S 6-2x-y O 2x Cl 0.7y Br 0.3y .

[0010] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 5.77 P 0.98 Ce 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 , Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.875 Br 0.375 , Li 5.85 P 0.9 Ce 0.1 S 4.55 O 0.2 Cl 0.875 Br 0.375 , Li 5.6 5P0.95 Ce 0.05 S 4.5 O 0.1 Cl 0.98 Br 0.42 , Li 5.77 P 0.98 Eu 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 , Li 5.77 P 0.98 Pr 0.02 S 4.7 1O 0.04 Cl 0.875 Br 0.375 , Li 5.77 P 0.98 Sm 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 .

[0011] In an embodiment of the present application, the particle size of the sulfide solid electrolyte satisfies: 0.5 µm < D50 < 4 µm, 7 µm < D90 < 10 µm.

[0012] A second aspect of the present application provides a full solid-state lithium battery, comprising a positive electrode, a negative electrode, and the sulfide solid electrolyte of the first aspect of the present application.

[0013] Advantages of the present application:

[0014] The present application provides a sulfide solid electrolyte and a full solid-state lithium battery, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1-x M x S 6-2x-y O 2x X y, M is at least one of variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of halogen, 0.002<=x<=0.3, 0.5<=y<=1.4, the molar ratio of M element and O element is 1:2, the cell parameters of the sulfide solid electrolyte satisfy: a=b=c=9.85~10Å, the ionic conductivity of the sulfide solid electrolyte is >8mS / cm. The sulfide solid electrolyte of the application, the variable valence rare earth element M is doped at the P site of the argyrodite LPSC solid electrolyte, the O element is doped at the S site, the value range of x and y is controlled within the range of the application and the molar ratio of M element and O element is controlled to be 1:2, the cell parameters of the sulfide solid electrolyte are controlled to satisfy: a=b=c=9.85~10Å, the structural stability and the anti-oxidation and reduction ability of the sulfide solid electrolyte are enhanced, and the air stability and the ionic conductivity of the sulfide solid electrolyte are improved, so that the longer cycle life and the stronger voltage resistance performance of the all-solid-state lithium battery are realized.

[0015] Of course, practicing any of the products or methods of the application does not necessarily require achieving all of the above advantages simultaneously. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the application, the drawings needed to be used in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other embodiments can also be obtained by those skilled in the art according to these drawings.

[0017] Figure 1 The X-ray diffraction pattern of the sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.875 Br 0.3 75 ) prepared for Example 1;

[0018] Figure 2 The X-ray diffraction pattern of the sulfide solid electrolyte (Li 5.77 P 0.98 Eu 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 ) prepared for Example 8;

[0019] Figure 3 The X-ray diffraction pattern of the sulfide solid electrolyte (Li 5.77 P 0.98 Pr 0.02 S4.71 O 0.04 Cl 0.875 Br 0.375 X-ray diffraction pattern of the sulfide solid electrolyte (Li

[0020] Figure 4 X-ray diffraction pattern of the sulfide solid electrolyte (Li 5.77 P 0.98 Sm 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 X-ray diffraction pattern of the sulfide solid electrolyte (Li

[0021] Figure 5 X-ray diffraction pattern of the sulfide solid electrolyte (Li 5.75 PS 4.75 Cl 0.875 Br 0.375 X-ray diffraction pattern of the sulfide solid electrolyte (Li DETAILED DESCRIPTION

[0022] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments and drawings of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those skilled in the art based on the present application belong to the scope of protection of the present application.

[0023] A first aspect of the present application provides a sulfide solid electrolyte with a chemical formula of Li 7+x-y P 1-x M x S 6-2x- y O 2x X y, M is at least one of variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of halogen, 0.002≤x≤0.3, 0.5≤y≤1.4, the molar ratio of M element to O element is 1:2; the cell parameters of the sulfide solid electrolyte satisfy: a=b=c=9.85~10Å, the ionic conductivity of the sulfide solid electrolyte is >8mS / cm. Wherein, the ionic conductivity of the sulfide solid electrolyte is >8mS / cm refers to that after the sulfide solid electrolyte powder is pressure formed at a pressure of 300MPa, the alternating current impedance spectrum test is carried out, the ionic conductivity of the sulfide solid electrolyte is >8mS / cm. Preferably, 0.02≤x≤0.1, 1.25≤y≤1.4. For example, x can be 0.002, 0.005, 0.01, 0.02, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3 or a range formed by any two of them, and y can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.1, 1.2, 1.25, 1.3, 1.4 or a range formed by any two of them.

[0024] In the present application, the rare earth element M partially substitutes P 5+ site, and a new [MO x S 4-x polyhedron structure is constructed. Such structure has stronger metal-ligand bond energy and electronic polarization ability, can significantly enhance the skeleton rigidity, improve the resistance of the material to oxidative stress and electric field disturbance, and prevent the original [PS4] 3- unit from disintegration under high voltage. After the oxygen anion replaces S 2- in the lattice, part of P-O or M-O bonds are formed, the ligand field strength in the lattice is enhanced, and the volatilization, migration or reduction tendency of sulfur element is reduced. This doping mechanism can effectively reduce the side reactions of S 2- conversion to S n or PS x , etc. during battery cycling, and improve the overall chemical stability. In addition, the variable valence rare earth element in the present application has unique reversible redox characteristics (such as Ce 4+ / Ce 3+ ), which can absorb or release electrons during battery cycling, thereby forming an internal charge buffer zone in the skeleton unit, dynamically adjusting the local electrochemical potential, and inhibiting the skeleton degradation. This electronic self-regulation mechanism is different from the simple interface buffer, and is more deeply integrated into the material structure itself. The doping of phosphorus / sulfur sites and the variable valence state of rare earth elements work together, so that the skeleton structure has self-adaptive adjustment ability to electrochemical stress, which alleviates the material damage risk caused by structure distortion, electronic density fluctuation and local valence change, enhances the structure stability and oxidation-reduction resistance of the sulfide solid electrolyte, significantly prolongs the service life of the all-solid-state lithium battery and improves its high voltage resistance performance.

[0025] In order to further ensure the controllability and functionality of the doping effect, the present application limits the molar ratio of rare earth element M to oxygen element O to 1:2, that is, each rare earth metal ion corresponds to two oxygen ions, thereby forming a stable or type coordination structural unit. By limiting this ratio, it is possible to effectively avoid Excessive introduction of rare earth ions can lead to lattice expansion, crystal phase impurity formation, or disordered anion sites. This also prevents isolated rare earth ions from lacking stable coordination, which can lead to decreased conductivity or accumulation of structural defects. Under this molar ratio, the resulting rare earth-oxygen structure is not only stably embedded in the electrolyte lattice but also exhibits a highly ordered local structure, which helps improve lattice rigidity and bonding energy, enhancing the sulfide solid electrolyte's resistance to external thermal perturbations and electrochemical stresses, and thus enhancing its structural stability. Furthermore, limiting the molar ratio of M to O to 1:2 ensures that the rare earth element M forms a complete electronic buffer structure in the lattice. During charge and discharge, its reversible redox behavior absorbs excess electrons, suppressing charge accumulation caused by interfacial side reactions, thereby delaying interfacial aging and maintaining interfacial electrochemical stability. In contrast, an unbalanced molar ratio of M to O can lead to rare earth enrichment, disrupting the lattice structure, or destabilizing the buffer structure due to insufficient oxygen content, thereby weakening the overall material performance.

[0026] In addition, rare earth elements doping at the P site optimizes the migration path of lithium ions by changing the stoichiometric balance of the crystal and inducing global lattice defects. Specifically, rare earth ions (such as Ce 4+ ) replace P 5+ Due to the lower oxidation state of rare earth ions, sulfur vacancies or other anion defects need to be introduced to maintain the electrical neutrality of the crystal. These sulfur vacancies will break the symmetry of the original sulfide framework structure, thereby enhancing the channel connectivity and migration ability of lithium ions. In addition, rare earth ion doping at the P position will affect the overall bonding strength of the crystal, such as weakening some Li-S bonds and changing the local environment of the surrounding lithium ions, further reducing the migration energy barrier of lithium ions. Rare earth ions doped at the P position have a significant effect on improving air stability. Due to the variable valence characteristics of rare earth ions (such as Ce 3+ and Ce 4+), which has excellent redox buffering capacity, can capture the oxidizing or reducing intermediate species generated by the decomposition of sulfides, thereby weakening the progress of the decomposition reaction, reducing the production of hydrogen sulfide decomposition products, and slowing down the degradation rate of the material in a humid or oxidizing environment. At the same time, the variable valence characteristics of rare earth elements allow them to form a stable passivation layer in the interface region, which can reduce the sensitivity of sulfides to oxygen and water in the air, further reduce their side reactions with air or electrode materials, thereby slowing down the oxidative degradation of the material and improving its stability. In addition, rare earth ions have variable oxidation states, which can be introduced by oxygen vacancies, reducing the water adsorption and reactivity of the material, thereby further improving its stability in a humid environment.

[0027] Further, by controlling 0.002≤x≤0.3, the variable valence rare earth doping amount can introduce oxygen coordination centers, form stable M-O bond structures, help adjust the electronic state distribution in the crystal, and enhance the stability of the sulfide framework structure. At the same time, this doping amount will not cause serious lattice distortion or second phase precipitation, allowing the unit cell parameters of the material to remain in the range of a=b=c=9.85~10Å while effectively introducing lithium vacancies and defects, optimizing the migration channel and improving ionic conductivity. If x<0.002, the rare earth element doping amount is too low, and the unit cell parameters of the material are less than 9.85Å. At this time, it is not possible to form sufficient M-O stable structures, and the electronic buffering and structure strengthening effects are significantly weakened, resulting in limited improvement in battery performance. If x>0.3, excessive rare earth doping will cause lattice distortion, impurity phase generation, and M element cluster precipitation, destroying the overall crystal uniformity, causing the unit cell parameters of the material to exceed 10Å, and instead causing ion migration channel blockage and material performance degradation. At the same time, by controlling 0.5≤y≤1.4, the appropriate halogen doping substitution of part of the sulfur elements helps to improve the rigidity of the framework and control the unit cell size, enhance the smoothness of the migration network, and improve the air resistance to water and oxygen, while still maintaining the overall stable structure of the original sulfide framework, avoiding excessive halogen introduction leading to crystal brittleness or phase separation. If y<0.5, the halogen doping ratio is too low, which is not enough to effectively improve the ionic conductivity and air stability of the material, and cannot provide sufficient synergistic regulation effect at the structural level, which is prone to performance degradation. If y>1.4, excessive halogen doping will cause serious lattice distortion and non-uniform phase generation, leading to rapid degradation of ionic conductivity, while increasing the brittleness of the material and inducing side reactions at the electrolyte / electrode interface, reducing its cycle stability.

[0028] Therefore, the present application dopes a variable-valence rare earth element M at the P position of the sulfide solid electrolyte and an O element at the S position, regulates the numerical ranges of x and y within the scope of the present application, and regulates the molar ratio of the M element to the O element to be 1:2, and controls the unit cell parameters of the sulfide solid electrolyte to satisfy: a=b=c=9.85~10Å, thereby enhancing the structural stability and anti-oxidation-reduction ability of the sulfide solid electrolyte, and at the same time improving the air stability and ionic conductivity of the sulfide solid electrolyte, thereby achieving a longer cycle life and stronger voltage resistance of the all-solid-state lithium battery.

[0029] In one embodiment of the present application, X is at least one of Cl, Br and I.

[0030] In one embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x M x S 6-2x-y O 2x X' 0.7y X'' 0.3y , X' or X'' are each independently Cl, Br, or I, and X' is different from X''. By introducing two halogens into the sulfide solid electrolyte and regulating the molar ratio of the two halogens to 7:3, the coexistence of the two halogens can optimize the bonding state between grains during sintering, reduce stress concentration and defect formation at grain boundaries, and thus reduce grain boundary resistance. The synergistic effect of the two halogens can form a denser and more uniform grain interface, which helps to inhibit interfacial reactions and improve the continuity of the overall ion conduction path.

[0031] In one embodiment of the present application, the sulfide solid electrolyte chemical formula is Li 7+x-y P 1-x M x S 6-2x- y O 2x Cl 0.7y Br 0.3y The sulfide solid electrolyte of the present application includes Cl and Br elements, and the molar ratio of Cl and Br elements is regulated to be 7:3. and There are differences in the ionic radius ( The ionic radius is about 1.81 Å. The ionic radius of the ions is about 1.96 Å). At a ratio of 7:3, it is possible to introduce ions with larger ions while ensuring that the lattice structure is not distorted. , thereby relieving the stress in the crystal and maintaining the stability of the face-centered cubic structure. If the Br ratio is too high, the lattice will expand excessively and destroy the Migrating channel; if the proportion of Br is too low, the electrochemical performance is not obviously improved, and it is found that 7:3 is a balance point considering the structural stability and functional optimization. By selecting the above sulfide solid electrolyte, the structural stability and redox resistance of the sulfide solid electrolyte can be further enhanced, and the air stability and ionic conductivity of the sulfide solid electrolyte can be further improved, so as to further improve the cycle life and voltage resistance performance of the all-solid-state lithium battery.

[0032] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x Ce x S 6-2x-y O 2x Cl 0.7y Br 0.3y , 0.02≤x≤0.1, 1.25≤y≤1.4. By doping Ce at the P site and doping oxygen at the S site of the argyrodite LPSC solid electrolyte, and the numerical range of x and y being within the above range, the structural stability and redox resistance of the sulfide solid electrolyte can be further enhanced, and the air stability and ionic conductivity of the sulfide solid electrolyte can be further improved, so as to further improve the cycle life and voltage resistance performance of the all-solid-state lithium battery.

[0033] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x Eu x S 6-2x-y O 2x Cl 0.7y Br 0.3y , 0.02≤x≤0.1, 1.25≤y≤1.4. By doping Eu at the P site and doping oxygen at the S site of the argyrodite LPSC solid electrolyte, and the numerical range of x and y being within the above range, the structural stability and redox resistance of the sulfide solid electrolyte can be further enhanced, and the air stability and ionic conductivity of the sulfide solid electrolyte can be further improved, so as to further improve the cycle life and voltage resistance performance of the all-solid-state lithium battery.

[0034] In an embodiment of the present application, the chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x Pr x S 6-2x-y O 2x Cl 0.7y Br 0.3y, 0.02≤x≤0.1, 1.25≤y≤1.4. Doping Pr at P site and oxygen at S site of argyrodite LPSC solid-state electrolyte, and the value range of x and y is in the above range, can further enhance the structural stability and oxidation-reduction resistance of sulfide solid-state electrolyte, and further improve the air stability and ionic conductivity of sulfide solid-state electrolyte, thereby further improving the cycle life and voltage endurance performance of all-solid-state lithium battery.

[0035] In an embodiment of the present application, the chemical formula of the sulfide solid-state electrolyte is Li 7+x-y P 1- x Sm x S 6-2x-y O 2x Cl 0.7y Br 0.3y , 0.02≤x≤0.1, 1.25≤y≤1.4. Doping Sm at P site and oxygen at S site of argyrodite LPSC solid-state electrolyte, and the value range of x and y is in the above range, can further enhance the structural stability and oxidation-reduction resistance of sulfide solid-state electrolyte, and further improve the air stability and ionic conductivity of sulfide solid-state electrolyte, thereby further improving the cycle life and voltage endurance performance of all-solid-state lithium battery.

[0036] In an embodiment of the present application, the chemical formula of the sulfide solid-state electrolyte is Li 5.77 P 0.98 Ce 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 , Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.875 Br 0.375 , Li 5.85 P 0.9 Ce 0.1 S 4.55 O 0.2 Cl 0.875 Br 0.375 , Li 5.6 5P 0.95 Ce 0.05 S 4.5 O 0.1 Cl 0.98 Br 0.42 , Li 5.77 P 0.98 Eu 0.02 S 4.71 O 0.04Cl 0.875 Br 0.375 , Li 5.77 P 0.98 Pr 0.02 S 4.7 1O 0.04 Cl 0.875 Br 0.375 , Li 5.77 P 0.98 Sm 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 The above sulfide solid electrolyte is selected to have higher structural stability and redox resistance, and higher air stability and ionic conductivity.

[0037] In an embodiment of the present application, the particle size of the sulfide solid electrolyte satisfies: 0.5 µm < D50 < 4 µm, 7 µm < D90 < 10 µm. The particle size of the sulfide solid electrolyte of the present application is within the above range, so that the sulfide solid electrolyte has good processing performance.

[0038] In an embodiment of the present application, the ionic conductivity of the sulfide solid electrolyte is > 8 mS / cm. Preferably, the ionic conductivity of the sulfide solid electrolyte is > 9 mS / cm. The sulfide solid electrolyte of the present application has high ionic conductivity while improving structural stability and air stability, and can improve the electrochemical performance of the all-solid-state lithium battery when applied to the all-solid-state lithium battery. It should be noted that the "ionic conductivity of the sulfide solid electrolyte" above refers to the ionic conductivity of the sulfide solid electrolyte obtained by performing an alternating current impedance spectrum test after the sulfide solid electrolyte powder is press-formed at a pressure of 300 MPa.

[0039] The preparation method of the sulfide solid electrolyte of the present application is not particularly limited, and any method that can achieve the purpose of the present application can be used, for example, the preparation method of the sulfide solid electrolyte can include: mixing raw materials and a solvent under inert atmosphere protection to obtain a suspension; drying the suspension by reduced pressure distillation to obtain a solid electrolyte precursor mixture; and sintering the solid electrolyte precursor mixture to obtain the sulfide solid electrolyte.

[0040] The types of raw materials and solvents are not particularly limited in the present application, and any material that can achieve the purpose of the present application can be used, for example, the raw materials can be Li2S, P2S5, LiCl, LiBr and rare earth oxides (such as CeO2, PrO2, Sm2O3, Eu2O3), and the solvent can be n-hexane, benzene, toluene, cyclohexane, n-pentane, cyclopentane, dimethyl carbonate. In the present application, the rare earth element M is doped into the P site in the form of tetravalence, and the P2S5 is doped into the S site in the form of pentavalence. Forming heterovalent substitution. To meet the charge neutralization condition and prevent the generation of a by-phase, the amount of phosphorus source is usually reduced in the raw material ratio , while the amount of Ce source, Pr source, Sm source or Eu source is appropriately increased to achieve partial substitution of Ce, Pr, Sm or Eu for P. In this process, the amount of S also needs to be adjusted accordingly to match the change in the P site tetrahedral structure. By controlling the molar ratio of the Ce source, Pr source, Sm source or Eu source, the rare earth element doping is more inclined to enter the P site, without generating excess by-products, thereby achieving stable P site doping.

[0041] The application does not particularly limit the amount of raw materials and solvents added, as long as the purpose of the application can be achieved. For example, the mass ratio of raw materials to solvent is 1:1-3. The application does not particularly limit the method of drying by vacuum distillation, as long as the purpose of the application can be achieved. For example, the temperature for drying by vacuum distillation is 40-60°C, and the vacuum degree is -0.09-0.10 MPa. The application does not particularly limit the sintering method, as long as the purpose of the application can be achieved. For example, a tubular furnace programmed heating method is used, first heated at 150-300°C for 2-4 hours, and then sintered at 500-600°C for 4-6 hours.

[0042] The second aspect of the application provides a full solid-state lithium battery, which comprises a positive electrode, a negative electrode and the sulfide solid-state electrolyte of the first aspect of the application.

[0043] The application does not particularly limit the positive electrode and negative electrode in the full solid-state lithium battery, as long as the purpose of the application can be achieved. For example, the positive electrode comprises a positive electrode active material, a sulfide solid-state electrolyte and conductive carbon, the positive electrode comprises a positive electrode active material, a sulfide solid-state electrolyte and conductive carbon, the positive electrode active material can be ternary positive electrode NCM523, NCM622, NCM712, NCM811, NCM90, or lithium iron phosphate, lithium manganese iron phosphate LiMn x Fe 1-x PO4, LiCoO2 material, lithium-rich manganese-based material (aLi2MnO3•(1-a)LiMO2) (0≤a≤1, M is at least one of Ni, Co or Mn), lithium nickel manganese oxide (LiNi 0.5 Mn 1.5 O4) material, etc., the sulfide solid-state electrolyte is the electrolyte in the application, and the conductive carbon can be Super P, carbon black; the mass ratio of the positive electrode active material, the sulfide solid-state electrolyte and the conductive carbon can be 60-80%:10-35%:3-10%. The negative electrode comprises lithium-indium alloy, lithium metal, graphite, silicon-carbon. Preferably, the full solid-state lithium battery further comprises a current collector arranged on the side of the positive electrode material; the current collector can be a carbon-coated aluminum foil or a pure aluminum foil.

[0044] The preparation method of the all-solid-state lithium battery is not particularly limited in the present application, and any method that can achieve the purpose of the present application can be used, for example, the preparation method of the all-solid-state lithium battery includes: mixing a positive active material, a sulfide solid electrolyte and conductive carbon to obtain a composite positive electrode powder; the sulfide solid electrolyte is loaded into a solid-state battery mold for first pressing to obtain an electrolyte layer; the composite positive electrode powder is added to one side of the electrolyte layer for second pressing to obtain a positive electrode; and a negative electrode material is added to the other side of the electrolyte layer for third pressing to obtain an all-solid-state lithium battery.

[0045] The sulfide solid electrolyte of the present application has high ionic conductivity and air stability, and the all-solid-state lithium battery comprising the sulfide solid electrolyte of the present application has excellent electrochemical performance.

[0046] Examples

[0047] Hereinafter, examples and comparative examples are given to more specifically describe the embodiments of the present application. Various tests and evaluations are carried out according to the following methods. In addition, unless otherwise specified, "parts" and "%" are based on mass.

[0048] Test method and equipment:

[0049] Ionic conductivity test

[0050] In an argon-filled glove box, 100 mg of sulfide solid electrolyte powder was weighed and placed in a mold battery with a diameter of 9 mm stainless steel sheet at both ends (Wuhan Chuangneng CN-01), and was pressure-formed at a pressure of 200 MPa, with an electrolyte sheet thickness of 1 mm. The mold battery was used for AC impedance spectroscopy test.

[0051] In an argon-filled glove box, 110 mg of sulfide solid electrolyte powder was weighed and placed in a mold battery with a diameter of 9 mm stainless steel sheet at both ends (Wuhan Chuangneng CN-01), and was pressure-formed at a pressure of 300 MPa, with an electrolyte sheet thickness of 1 mm. The mold battery was used for AC impedance spectroscopy test.

[0052] AC impedance spectroscopy test: The electrolyte impedance was measured by electrochemical impedance spectroscopy (EIS) at 25°C, and the impedance was measured by applying a direct current (DC) polarization voltage of 1V on an electrochemical workstation (ChenHua, CHI630E), with an amplitude of 50mV and a frequency range of 1Hz~10MHz. The ionic conductivity of the electrolyte material was calculated according to the following ionic conductivity formula, as follows:

[0053] Wherein, σ is the ionic conductivity, unit is S cm –1L is the thickness of the electrolyte sheet, in cm; R is the electrolyte resistance, in Ω; S is the effective contact area of the stainless steel sheet with the electrolyte powder, in cm 2 .

[0054] Air stability test

[0055] Air stability is mainly described by the retention rate of ionic conductivity of sulfide solid electrolyte and the amount of hydrogen sulfide generated under air exposure.

[0056] Ionic conductivity retention rate test: The ionic conductivity of the sulfide solid electrolyte is tested using the above-mentioned ionic conductivity test method, and is recorded as the conductivity before exposure; then the sulfide solid electrolyte is directly exposed to air at 40% air humidity and 25°C, and the sulfide solid electrolyte is recovered at 10 minutes, 1 hour and 24 hours, respectively, and the ionic conductivity is tested using the above-mentioned ionic conductivity test method, and is recorded as the conductivity after exposure. The conductivity retention rate = conductivity after exposure / conductivity before exposure x 100%.

[0057] Hydrogen sulfide generation test: Under 40% air humidity and 25°C, a sulfide solid electrolyte with a mass of m is placed in a closed reaction container with a volume of V together with a hydrogen sulfide detector, ensuring good airtightness in the container. Record the reading of the hydrogen sulfide detector at fixed time intervals (record once every 30 seconds, a total of 10 minutes) to obtain the gas concentration c of the sulfide solid electrolyte exposed for 10 minutes. According to the gas concentration c, the volume V of the reaction container and the mass m of the sulfide solid electrolyte, the hydrogen sulfide generation per unit mass of sample is calculated. Hydrogen sulfide generation = (c x V) / m, in cm 3 / g.

[0058] X-ray powder diffraction test

[0059] X-ray powder diffraction (XRD) technology is used to analyze the crystal structure of the sample. The experiment uses a Bruker D8 Advance diffractometer equipped with Cu Kα radiation (λ = 1.5406 Å) as the light source. The test parameters are set as follows: tube voltage is 40 kV, tube current is 40 mA, scanning range is 2θ = 5°-90°, scanning step is 0.02°, and scanning rate is 5° / min. The sample is uniformly dispersed in the form of powder on a glass slide without diffraction background, and is treated by compaction to reduce the influence of inter-particle voids on the diffraction results.

[0060] Cell parameter analysis: The XRD data were processed and analyzed by Jade software. First, the original data were imported into the software, and after background subtraction and signal optimization, they were exported as text format. The text file was imported into the refinement software FullProf, and an initial model was established according to the known crystal structure of the sample. The preliminary cell parameters and space group were input, and the instrument parameters such as zero point offset, sample displacement were adjusted, and the preliminary fitting was completed.

[0061] During the refinement process, the peak shape parameters (such as peak width, peak shape factor), background function, cell parameters (a, b, c, α, β, γ) and atomic position and occupancy were optimized step by step, and finally the convergence of fitting was realized. The evaluation of fitting results was based on the goodness of fit Chi2, and the fitting quality was judged by combining the residual spectrum. When the refinement result converges (Chi2<3), the cell parameters a, b, c can be obtained from the result text output by the software.

[0062] Test of particle size distribution

[0063] A Zeiss Sigma 300 scanning electron microscope (SEM) was used to observe the surface morphology and particle size distribution of the sulfide solid-state electrolyte. It was fixed on the sample stage, and the sample stage was placed in the vacuum chamber. The acceleration voltage, beam intensity and working distance of the SEM were adjusted to optimize the imaging effect, and the surface morphology information was obtained by the secondary electron detector. Image J software was used to measure and count the particle size of the sulfide solid-state electrolyte in the SEM image, and the particle size distribution was obtained.

[0064] Electrochemical performance test

[0065] The electrochemical performance test was mainly carried out by assembling full solid-state batteries with sulfide solid-state electrolyte and layered high-nickel NCM811 ternary positive electrode material.

[0066] Preparation of all-solid-state battery: (1) Preparation of positive electrode material: the positive active material NCM811, the sulfide solid electrolyte of the application and conductive carbon were mixed in a mass ratio of 75:20:5, ground in a mortar for 30 minutes to obtain a composite positive electrode powder; (2) Negative electrode material: lithium-indium alloy (lithium content of 30wt%); (3) Sulfide solid electrolyte: the sulfide solid electrolyte of the application was used; (4) Assembly of all-solid-state battery: in an argon-filled glove box, first, 100 mg of sulfide solid electrolyte was weighed and added to a solid-state battery mold with an inner diameter of 10 mm, and was pressed to 300 Mpa for 1 minute to obtain an electrolyte layer; 10 mg of composite positive electrode powder was added to one side of the electrolyte layer, covered with a 15 µm aluminum foil, and pressed to 100 Mpa for 1 minute to obtain a positive electrode; then 100 µm lithium-indium alloy negative electrode material was added to the other side, and after slight pressing at 50 Mpa, the mold was assembled to obtain an assembled all-solid-state lithium ion battery, which was verified for airtightness and then taken out of the glove box and transferred to a battery test system for electrochemical charge and discharge cycle test.

[0067] Charge and discharge test: the charge and discharge performance test of the battery was carried out using a LAND battery test system at a constant temperature of 25℃.

[0068] Constant current charge and discharge test can directly reflect the electrochemical performance of active materials in the battery, and is an important means to evaluate the practical application potential of materials. In the test, the current density is based on the mass of the material, and the specific capacity corresponding to 1C is defined as 120 mAh / g, where 0.2C is 24 mAh / g. During the 0.2C rate cycle, first, the battery was charged from 2.6 V to a preset cut-off voltage (3.9 V, 4.0 V, 4.1 V, 4.2 V, 4.3 V or 4.4 V) at a constant current, and the highest voltage at which the battery could stably operate was selected as the cut-off voltage, then discharged to 2.6 V at the same current, and the whole process was completed in constant current mode. The capacity retention rate (initial efficiency) of the all-solid-state lithium ion battery in the first 0.2C charge and discharge process, the capacity retention rate after 200 cycles in the 0.2C charge and discharge cycle process, and the cycle number of the all-solid-state lithium ion battery when the discharge capacity suddenly and sharply decreased (discharge capacity jump of the application) were recorded.

[0069] The specific capacity of the first charge and discharge process of the battery is used to calculate the first discharge efficiency (initial efficiency), which is calculated as: initial efficiency = first discharge capacity / first charge capacity × 100%. This index can be used to evaluate the capacity loss caused by irreversible reactions (such as electrolyte decomposition or solid-state electrolyte interface film formation) in the first cycle.

[0070] Capacity retention rate after 200 cycles = 200th discharge capacity / first discharge capacity × 100%.

[0071] Example 1

[0072] In an Ar atmosphere, raw materials of Li2S, P2S5, LiCl, LiBr and rare earth oxide CeO2 with a molar ratio of 2.275:0.475:0.875:0.375:0.05 were weighed, 1 kg of the raw materials was added into 1 kg of n-hexane for mixing to obtain a suspension; the suspension was subjected to vacuum distillation drying under the condition of a temperature of 40°C and a vacuum degree of -0.098 Mpa to obtain a solid electrolyte precursor mixture; in an Ar atmosphere, the solid electrolyte precursor mixture obtained above was heated at 200°C for 3 hours and then at 550°C for 5 hours by using a tube furnace program heating method to obtain a sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.6 5O 0.1 Cl 0.875 Br 0.375 ), and an X-ray diffraction pattern thereof is shown in Figure 1 .

[0073] Examples 2 to 7

[0074] Except that the molar ratio of raw materials was adjusted to obtain sulfide solid electrolytes with different chemical formulas in Table 1, the remaining steps were the same as those in Example 1.

[0075] Example 8

[0076] The raw materials were replaced with “raw materials of Li2S, P2S5, LiCl, LiBr, P2O5, elemental S and rare earth oxide Eu2O3 with a molar ratio of 2.26:0.488:0.875:0.375:0.002:0.01:0.01”, and the remaining steps were the same as those in Example 1 to obtain a sulfide solid electrolyte (Li 5.77 P 0.9 8Eu 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 ), and an X-ray diffraction pattern thereof is shown in Figure 2 .

[0077] Example 9

[0078] The raw materials were replaced with “raw materials of Li2S, P2S5, LiCl, LiBr and rare earth oxide PrO2 with a molar ratio of 2.26:0.49:0.875:0.375:0.02”, and the remaining steps were the same as those in Example 1 to obtain a sulfide solid electrolyte (Li 5.77 P 0.98 Pr0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 ), the remaining steps are the same as those in Example 1. Its X-ray diffraction pattern is as follows Figure 3 shown.

[0079] Example 10

[0080] The raw materials were replaced with "Li2S, P2S5, LiCl, LiBr, P2O5, S element and rare earth oxide Sm2O3 with a molar ratio of 2.26:0.488:0.875:0.375:0.002: 0.01:0.01" to obtain a sulfide solid electrolyte (Li 5.77 P 0.9 8Sm 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 ), the remaining steps are the same as those in Example 1. Its X-ray diffraction pattern is as follows Figure 4 shown.

[0081] Example 11

[0082] The raw materials were replaced with "Li2S, P2S5, LiCl, LiI and rare earth oxide CeO2 with a molar ratio of 2.275:0.475:0.875:0.375:0.05" to obtain a sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.875 I 0.375 ), the remaining steps are the same as those in Example 1.

[0083] Example 12

[0084] The raw materials were replaced with "Li2S, P2S5, LiBr, LiI and rare earth oxide CeO2 with a molar ratio of 2.275:0.475:0.875:0.375:0.05" to obtain a sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Br 0.875 I 0.375 ), the remaining steps are the same as those in Example 1.

[0085] Example 13

[0086] The raw material was replaced with "a raw material of Li2S, P2S5, LiCl, LiBr, LiI, and rare earth oxide CeO2 in a molar ratio of 2.275:0.475:0.875:0.25:0.125:0.05", and the sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0. 1Cl 0.875 Br 0.25 I 0.125 ) was obtained, and the remaining steps were the same as in Example 1.

[0087] Example 14

[0088] The raw material was replaced with "a raw material of Li2S, P2S5, LiCl, LiBr, LiI, and rare earth oxide CeO2 in a molar ratio of 2.275:0.475:0.875:0.25:0.125:0.05", and the sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 1.25 ) was obtained, and the remaining steps were the same as in Example 1.

[0089] Example 15

[0090] The raw material was replaced with "a raw material of Li2S, P2S5, LiCl, LiBr, LiI, and rare earth oxide CeO2 in a molar ratio of 2.275:0.475:0.875:0.25:0.125:0.05", and the sulfide solid electrolyte (Li 5.77 P 0.98 Ce 0.01 Eu 0.01 S 4.71 O 0.04 Cl 0.875 Br 0.375 ) was obtained, and the remaining steps were the same as in Example 1.

[0091] Example 16

[0092] The raw material was replaced with "a raw material of Li2S, P2S5, LiCl, LiBr, LiI, and rare earth oxide CeO2 in a molar ratio of 2.275:0.475:0.875:0.25:0.125:0.05", and the sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.625 Br0.625 The remaining steps were the same as in Example 1 except that the starting materials were replaced with "starting materials of Li2S, P2S5, LiCl, and LiBr in a molar ratio of 2.25: 0.5: 0.875: 0.375".

[0093] Example 17

[0094] The sulfide solid electrolyte was the same as in Example 1, the positive electrode active material for the electrochemical performance test was LiFe 1.2 Ni 0.13 Co 0.13 Mn 0.54 O2, the negative electrode material was graphite, and the remaining electrochemical performance test steps were the same as the above test method.

[0095] Example 18

[0096] The sulfide solid electrolyte was the same as in Example 1, the positive electrode active material for the electrochemical performance test was LiFe 0.5 Mn 0.5 PO4, the negative electrode material was silicon-carbon, and the remaining electrochemical performance test steps were the same as the above test method.

[0097] Comparative Examples 1 to 5

[0098] The remaining steps were the same as in Example 1 except that the starting materials were adjusted in molar ratio to obtain sulfide solid electrolytes of different chemical formulas shown in Table 1.

[0099] Comparative Example 6

[0100] The starting materials were replaced with "starting materials of Li2S, P2S5, LiCl, and LiBr in a molar ratio of 2.25: 0.5: 0.875: 0.375", to obtain a sulfide solid electrolyte (Li 5.75 PS 4.75 Cl 0.875 Br 0.375 ) except that the remaining steps were the same as in Example 1. Its X-ray diffraction pattern is shown in Figure 5 .

[0101] Comparative Example 7

[0102] The starting materials were replaced with "starting materials of Li2S, P2S5, LiCl, LiBr, and CeS2 in a molar ratio of 2.275: 0.475: 0.875: 0.375: 0.05", to obtain a sulfide solid electrolyte (Li 5.8 P 0.95 Ce 0.05 S 4.75 Cl 0.875 Br 0.375 ) except that the remaining steps were the same as in Example 1.

[0103] Comparative Example 8

[0104] The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li 5.76 P 0.99 Ce 0.01 S 4.75 Cl 0.875 Br 0.3 75 The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li

[0105] Comparative Example 9

[0106] The remaining steps were the same as those of Example 1 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li 5.75 PS 4.65 O 0.1 Cl 0.875 Br 0.375 The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li

[0107] Comparative Example 10

[0108] The remaining steps were the same as those of Comparative Example 8 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li 5.75 PS 4.73 O 0.02 Cl 0.875 Br 0.375 The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li

[0109] Comparative Example 11

[0110] The remaining steps were the same as those of Example 1 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li 5.42 P 0.98 Ce 0.02 S 4.36 O 0.04 Cl 1.6 The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li

[0111] Comparative Example 12

[0112] The remaining steps were the same as those of Comparative Example 6 except that the raw materials were replaced with "raw materials of Li2S, P2S5, LiCl, LiBr, P2O5 in a molar ratio of 2.25: 0.48: 0.875: 0.375: 0.02" to obtain a sulfide solid electrolyte (Li 5.9 P 0.7 Sn 0.2 Ce 0.1 S 4.4 O 0.2 Cl 1.4The remaining steps are the same as those in Example 1 except that the step of adding 0.5 g of Li2S and 0.5 g of P2S5 is replaced by the step of adding 0.5 g of Li2S and 0.5 g of P2S5 and 0.5 g of LiI.

[0113] The preparation parameters and performance parameters of the sulfide solid electrolytes of each example and comparative example are shown in Table 1, and the performance parameters of the all-solid-state batteries prepared therefrom are shown in Tables 2 and 3.

[0114] Table 1 Preparation parameters and performance parameters of sulfide solid electrolytes

[0115] In Table 1, " / " represents no relevant parameter.

[0116] Table 2 Performance parameters of all-solid-state batteries

[0117] Table 3 Performance parameters of all-solid-state batteries of different systems

[0118] As can be seen from Table 1, the sulfide solid electrolyte of the present application satisfies the chemical formula Li 7+x-y P 1-x M x S 6-2x- y O 2x X y , M is at least one of the variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of halogens, 0.002≤x≤0.3, 0.5≤y≤1.4, the obtained sulfide solid electrolyte has a lattice parameter satisfying a=b=c=9.85~10Å; the particle size of the sulfide solid electrolyte satisfies 0.5µm<D50<4µm, 7µm<D90<10µm; the sulfide solid electrolyte has high ionic conductivity and air stability; after the sulfide solid electrolyte is press-formed under a pressure of 300 MPa, an alternating current impedance spectrum test is performed, the ionic conductivity of the sulfide solid electrolyte is >8 mS / cm, the conductivity retention rate is ≥75% after exposure to 40% air humidity for 10 minutes, the conductivity retention rate is ≥63% after exposure to 40% air humidity for 1 hour, the conductivity retention rate is ≥40% after exposure to 40% air humidity for 24 hours; the amount of hydrogen sulfide generated is <0.049 cm 3V. From Table 2, it can be seen that the sulfide solid-state electrolyte of the present application applied in the all-solid-state lithium battery can improve the initial discharge efficiency, cycle performance and cut-off voltage of the all-solid-state lithium battery, the initial discharge efficiency is ≥70.2%, the capacity retention rate after 200 cycles at 0.2C is ≥95.3%, the cycle number at 0.2C is ≥303 times, and the cut-off voltage is ≥4.1V, that is, the initial efficiency, cycle life and voltage resistance performance of the all-solid-state lithium battery are improved. From Table 3, it can be seen that the sulfide solid-state electrolyte of the present application applied in the all-solid-state lithium battery of different systems, the all-solid-state lithium battery obtained has high initial discharge efficiency, good cycle performance and high cut-off voltage. In summary, the sulfide solid-state electrolyte of the present application enhances the structural stability and anti-oxidation and reduction ability of the sulfide solid-state electrolyte, and at the same time improves the air stability and ionic conductivity of the sulfide solid-state electrolyte, thereby realizing longer cycle life and stronger voltage resistance performance of the all-solid-state lithium battery.

[0119] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A sulfide solid electrolyte, characterized in that: The chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1- x M x S 6-2x-y O 2x X y , M is at least one of the variable valence rare earth elements Ce, Eu, Pr and Sm, X is at least one of the halogens, 0.002≤x≤0.3, 0.5≤y≤1.4, and the molar ratio of the M element to the O element is 1:2; The unit cell parameters of the sulfide solid electrolyte satisfy: a=b=c=9.85~10Å, and the ionic conductivity of the sulfide solid electrolyte is greater than 8mS / cm.

2. The sulfide solid electrolyte according to claim 1, characterized in that 0.02≤x≤0.1,1.25≤y≤1.

4.

3. The sulfide solid electrolyte according to claim 1, characterized in that X is at least one of Cl, Br and I.

4. The sulfide solid electrolyte according to claim 1, characterized in that The chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1-x M x S 6-2x-y O 2x X' 0.7y X'' 0.3y , X' or X'' are each independently Cl, Br or I, and X' and X'' are different.

5. The sulfide solid electrolyte according to claim 1, characterized in that The chemical formula of the sulfide solid electrolyte is Li 7+x-y P 1-x M x S 6-2x-y O 2x Cl 0.7y Br 0.3y .

6. The sulfide solid electrolyte according to claim 1, characterized in that The sulfide solid electrolyte is Li 5.77 P 0.98 Ce 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 、Li 5.8 P 0.95 Ce 0.05 S 4.65 O 0.1 Cl 0.875 Br 0.375 、Li 5.85 P 0.9 Ce 0. 1S 4.55 O 0.2 Cl 0.875 Br 0.375 、Li 5.65 P 0.95 Ce 0.05 S 4.5 O 0.1 Cl 0.98 Br 0.42 、Li 5.77 P 0.98 Eu 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 、Li 5.77 P 0.98 Pr 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 、Li 5.77 P 0.98 Sm 0.02 S 4.71 O 0.04 Cl 0.875 Br 0.375 .

7. The sulfide solid electrolyte according to claim 1, characterized in that The particle size of the sulfide solid electrolyte satisfies the following requirements: 0.5µm<D50<4µm, 7µm<D90<10µm.

8. An all-solid-state lithium battery comprising a positive electrode, a negative electrode, and the sulfide solid electrolyte according to any one of claims 1 to 7.

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