A doped sulfide solid-state electrolyte, and a preparation method and use thereof

Abstract

The application belongs to the technical field of battery materials, and provides a doped sulfide solid electrolyte as well as a preparation method and application thereof.The doped sulfide solid electrolyte comprises an oxide containing a metal element A as a dopant;the atomic valence electron layer of A is fully filled and A is a soft acid element;in the doped sulfide solid electrolyte, the valence state of A is not more than +3.By doping the oxide of a specific A, the soft acid element A is more likely to combine with the soft base S 2‑ to replace P, to form an A-S covalent bond with higher polarity than P-S, thereby improving the air stability of the sulfide solid electrolyte and effectively inhibiting the hydrolysis of the sulfide electrolyte; at the same time, the valence electron layer of the specific electronic arrangement structure of the metal element A is fully filled, the stability is strong, and the oxidation resistance of the sulfide solid electrolyte can be effectively improved. And A presents a lower valence state in the doped sulfide solid electrolyte, avoiding the influence of high-valence metal doping elements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of battery materials, and relates to a doped sulfide solid electrolyte and a preparation method and application thereof. BACKGROUND

[0002] With the deep adjustment of global energy structure and the rapid development of new energy vehicles, energy storage systems and other fields, the safety hidden trouble problem caused by the use of organic flammable electrolyte in traditional lithium ion batteries is increasingly prominent. Under the background of the increasing demand for high energy density, safety risks such as thermal runaway, short circuit and electrolyte leakage have become one of the bottlenecks restricting the further development. Under this background, all-solid-state batteries, which use solid electrolyte to replace liquid electrolyte, fundamentally eliminate the hidden trouble problems of flammability and volatility, and are considered as an important development direction of the next generation of high safety and high energy density energy storage.

[0003] The core components of all-solid-state batteries include positive electrode materials, solid electrolytes and negative electrode materials. The solid electrolyte, as the key medium connecting the positive and negative electrodes, determines the overall performance of the battery to a great extent, especially the key indicators such as ionic conductivity, interface stability, cycle life and safety. Compared with traditional liquid electrolytes, solid electrolytes not only need to have good ion transport capacity, but also need to have excellent chemical stability and mechanical strength to adapt to complex electrochemical environments and effectively inhibit the growth of lithium dendrites. At present, the solid electrolytes studied more widely mainly include three categories of oxide type, polymer type and sulfide type. Among them, sulfide solid electrolyte is concerned because of its extremely high lithium ion conductivity (usually up to 10 -2 ~10 -3 S / cm, close to or even exceeding that of liquid electrolyte), and becomes one of the important candidate materials for realizing high-performance all-solid-state batteries.

[0004] Sulfide solid electrolytes include argyrodite type (such as Li6PS5Cl), LGPS type (such as Li 10 GeP2S 12 ), Thio-LISICON type (such as Li2S-GeS2-P2S5 system) or glassy (ceramic state) and the like. In these materials, S 2-The large ionic radius and low lattice energy of the ions enable fast migration of lithium ions in their crystal structure, resulting in excellent ionic conductivity. In addition, sulfide solid-state electrolytes also have relatively low hardness and high ductility, which makes it easier to form close physical contact with positive electrode particles during pressing, helping to reduce interface voids and improve overall density. At the same time, its ionic conductivity at low temperature decays less, so it is also considered as an ideal electrolyte material suitable for low temperature environment. In practical applications, sulfide solid-state electrolytes can also be used as positive electrode binders or filler phases, replacing traditional PVDF / carbon additive combinations, thus having the potential to realize the "full solidification" of positive electrode materials.

[0005] However, although sulfide solid-state electrolytes show significant advantages in ionic conductivity, they still have many shortcomings in air stability, oxidation stability, and structural stability during long-term cycling, which seriously limits their large-scale application in full solid-state batteries.

[0006] First, sulfide solid-state electrolytes generally have poor air stability. In humid air, hard acid centers (such as P 5+ ) in sulfides are easy to combine with hard bases (such as O 2- ) derived from water oxygen in the air to form P-O bonds, or weak acid centers S 2- ions are prone to combine with H + to generate H2S gas. This reaction mechanism not only causes structural damage to the electrolyte itself, but also releases harmful gases, affecting the safety of the production environment. Therefore, the synthesis, processing and subsequent battery assembly process of sulfide solid-state electrolytes must usually be carried out in a strict dry inert atmosphere, greatly increasing the process complexity and manufacturing cost.

[0007] Second, sulfide solid-state electrolytes have poor oxidation stability, with the oxidation potential of S 2- usually at 2.0-2.5V, much lower than the working voltage range of many high-voltage positive electrode materials (for example, the working voltage of high-nickel ternary materials can reach 4.3V or more). This means that when sulfide electrolytes come into contact with positive electrode materials, especially high-voltage positive electrode materials, irreversible oxidation reactions may occur, causing electrolyte decomposition and generating high-impedance interface products, thereby hindering the transport of lithium ions.

[0008] This is also reflected in the problem that when sulfide solid-state electrolytes come into direct contact with oxide-based positive electrode materials, a significant chemical potential difference is generated between the two. At this time, Li + will migrate from the electrolyte side to the positive electrode material until equilibrium is reached. At this time, Li +Defect layer, i.e. space charge layer, which grows at the beginning of the battery charging, will eventually lead to large interface resistance and delay Li + Transport on the interface.

[0009] Third, although the low hardness of sulfide solid electrolyte is conducive to forming good physical contact with the positive material during pressing, its high brittleness brings difficulties to the preparation of large-area uniform thin films. In the wet coating process, if a slurry containing a polar solvent is used, it may cause the sulfide electrolyte to react with the solvent, produce impurities or release H2S gas, affecting the quality and purity of the electrolyte film. In addition, due to the weak mechanical properties of the material itself, cracks are easily generated under the repeated charging and discharging stress, and even penetrated by lithium dendrites, causing serious internal short circuit risk.

[0010] To address the above problems, an effective modification strategy is to introduce a layer of air-stable coating material such as Li2CO3 and LiF on the surface of the sulfide solid electrolyte to physically isolate water and oxygen from direct contact with the sulfide, thereby alleviating its degradation reaction. However, it is difficult to control the thickness of the coating layer, and an excessively thick coating may affect the lithium ion transmission channel and reduce the ionic conductivity of the electrolyte; on the other hand, the bonding force between the coating layer and the sulfide matrix is limited, and may peel off under multiple cycles or high pressure conditions, thereby losing the protective effect.

[0011] Another effective modification method is to optimize the crystal structure and chemical stability of the sulfide solid electrolyte through element doping. Compared with the coating method, element doping tends to start from the intrinsic level of the material, and adjusts its electronic structure and chemical bonding properties by introducing specific cations or anions. Commonly used doping elements include high-valence metal cations such as Al 3+ , Ga 3+ , Zr 4+ , Ti 4+ or Sn 4+ , etc. These high-valence cations can partially replace low-valence sites in the sulfide structure (such as Li + ), thereby reducing the concentration of lithium vacancies and inhibiting the adsorption and reaction of H2O / O2. In addition, the M-S bond formed by the high-valence cation and sulfur is usually stronger than the Li-S bond, which helps to enhance the structural stability of the material and delay the oxidation reaction of sulfur. For example, Zr 4+ doped Li 10 GeP2S 12 materials show higher air stability and better oxidation resistance.

[0012] However, the choice of element doping is not indiscriminable, especially the introduction of unstable high valence cations may have a negative impact on the performance of electrolyte. High valence doping elements with poor chemical stability or unstable in the electrochemical window, not only will destroy the original lithium ion transport channel, or further migrate to the interface, thereby hindering ion transport to cause a significant decrease in ionic conductivity (such as excess Al 3+ . Doping will reduce the Li 10 conductivity of GeP2S 12 ), also cause local lattice distortion, or induce other side reactions (such as H2S or Li3PO4), and may consume active lithium, thereby accelerating the capacity decay of the battery. For example, some mechanisms include: 1) some high valence cations may be reduced to low valence state at low potential (such as for lithium metal negative electrode), for example Sn 4+ may be reduced to Sn 2+ / Sn 0 , Ge 4+ may be reduced to Ge 2+ / Ge 0 , etc., which will destroy the lattice integrity of the electrolyte; and the reduction product Sn 0 nanoparticles will form an electronic seepage network when segregated at the grain boundary, exacerbating the self-discharge phenomenon, affecting the long-term stability of the battery; at the same time, the reduction process is also accompanied by the oxidation reaction of S 2- , releasing H2S gas or forming Li2S insulating layer, increasing the interface impedance; 2) some high valence elements participate in side reactions after migration at the interface, for example, Ta 5+ reacts with lithium metal in the interface region to generate high impedance Li x TaO y compound, which greatly consumes active lithium and forms a high impedance interface layer; 3) under high voltage (>4V vs. Li + / Li) conditions, some high valence elements (such as Nb 5+ , Ta 5+ , etc.) may catalyze the oxidation reaction between the positive electrode material and the sulfide electrolyte, accelerating the capacity decay; 4) the ionic radius of these high valence ions used for doping often does not match the matrix, leading to local stress concentration, more easily inducing the formation of cracks or pores, promoting the growth and penetration of lithium dendrites; 5) the introduction of some high valence elements may also reduce the thermal stability of sulfide solid electrolyte, for example, after doping Ta 5+ in Li7P3S 11 , its decomposition temperature decreases from the original 300℃ to about 250℃, which brings new problems to the application under high temperature working conditions.

[0013] Therefore, there is still a need to develop a new modification and optimization scheme for sulfide solid electrolytes, which can significantly improve the air stability, oxidation resistance and structural stability during long-term cycling without affecting the intrinsic high ionic conductivity, so as to meet the demand for large-scale application in the construction of all-solid-state batteries. SUMMARY

[0014] In view of the problems in the prior art, the purpose of the present application is to provide a doped sulfide solid electrolyte and a preparation method and use thereof, wherein the doped sulfide solid electrolyte comprises an oxide containing a metal element A as a dopant; the atomic valence electron shell of A is fully filled and A is a soft acid element; and the valence state of A in the doped sulfide solid electrolyte is not more than +3. By doping the oxide of a specific A, the soft acid element A is more likely to combine with the soft base S 2- preferentially combines with P to form an A-S covalent bond with higher polarity than P-S, thereby improving the air stability of the sulfide solid electrolyte and effectively inhibiting the hydrolysis of the sulfide electrolyte. At the same time, the valence electron shell of the specific electronic distribution structure of the metal element A is fully filled, which is stable and can effectively improve the oxidation resistance of the sulfide solid electrolyte. Moreover, A has a low valence state in the doped sulfide solid electrolyte, avoiding the influence of high-valence metal dopant elements.

[0015] To achieve this purpose, the present application adopts the following technical solutions:

[0016] In a first aspect, the present application provides a doped sulfide solid electrolyte, comprising a sulfide solid electrolyte base component, wherein the sulfide solid electrolyte base component contains a dopant, and the dopant comprises an oxide of a metal element A; the atomic valence electron shell of the metal element A is fully filled, and A is a soft acid element; and the valence state of A in the doped sulfide solid electrolyte is not more than +3.

[0017] In the doped sulfide solid electrolyte of the present application, the oxide of the metal element A is used as a doping component, and the specific metal element A belongs to a soft acid element. According to the HSAB theory, soft acids preferentially combine with soft bases S 2- to form an A-S covalent bond with higher polarity than P-S, thereby improving the air stability of the sulfide solid electrolyte and effectively inhibiting the hydrolysis of the sulfide electrolyte. At the same time, the valence electron shell of the specific electronic distribution structure of the metal element A is fully filled, which is stable and can effectively improve the oxidation resistance of the sulfide solid electrolyte. Specifically, when the valence electron shell of an atom is fully filled (such as the valence electron shell of Yb is 4f 146s²) has extremely high electronic configuration stability, similar to noble gases (He, Ne, Ar, etc.). The energy of this state is the lowest, and it requires extremely high energy to further lose or accept electrons; to destroy the full-filled electron shell (for example, remove an electron), it needs to overcome a large ionization energy, so it is not easy to be oxidized by oxidizing agents (such as O2, H + , high-valence metal ions, etc.), and when applied to sulfide solid electrolytes, the band gap between the full-filled valence band and the empty conduction band is large, and electrons are difficult to transition, so it is not easy to participate in redox reactions. When the doped elements in the sulfide solid electrolyte are more stable, the oxidation resistance and air stability of the electrolyte are higher, because the high-stability doped elements have good compatibility with the matrix, which can reduce lattice distortion and reduce sulfur vacancy concentration, which is conducive to stabilizing the lattice structure and reducing defect activity; high-stability doped elements form strong bonds in sulfide lattices, which can preferentially occupy sites vulnerable to oxygen attack (such as sulfur vacancies V s 2- ), preventing oxygen (O2 / H2O) from penetrating into the electrolyte and inhibiting sulfur oxidation and H2S release; high-stability doped elements can reduce the valence state fluctuation of sulfur (avoiding S 2- → S 0 / S 4+ ), thereby inhibiting side reactions.

[0018] The following is a preferred technical solution of the present application, but not as a limitation of the technical solutions provided by the present application. Through the following technical solutions, the technical purposes and beneficial effects of the present application can be better achieved and realized.

[0019] As a preferred technical solution of the present application, the sulfide solid electrolyte base component includes at least one of Thio-LISICON series electrolyte, Argyrodite series electrolyte or glass-ceramic state electrolyte. Preferably, it contains S elements and P elements.

[0020] Preferably, the chemical formula of the Thio-LISICON series electrolyte includes Li 4-x M 1-x P x S4, (M = at least one of Si, Ge or Sn), 0 < x < 1; for example, Li 3.25 Ge 0.25 P 0.75 S4, etc.

[0021] Preferably, the chemical formula of the Argyrodite series electrolyte includes Li 7-a P a S 6-b X b , X = at least one of F, Cl, or Br, 0 ≤ a ≤ 1, 0 < b ≤ 2; for example, Li6PS5Cl, etc.

[0022] Preferably, the metal element A includes at least one of Be, Mg, Ca, Sr, Ba, Zn, Pd, Yb, or No.

[0023] Preferably, the oxide of the metal element A includes at least one of BeO, MgO, CaO, SrO, BaO, ZnO, PdO, Yb2O3 or No2O3.

[0024] Preferably, the molar ratio of the metal element A to the molar ratio of the basic component of the sulfide solid electrolyte is (0.01~0.2):1, for example, it can be 0.01:1, 0.02:1, 0.03:1, 0.05:1, 0.06:1, 0.08:1, 0.1:1, 0.12:1, 0.14:1, 0.16:1, 0.18:1 or 0.2:1, etc.

[0025] Preferably, the chemical structure of the doped sulfide solid electrolyte includes Li a P b S c A e X d O f Wherein, X includes at least one of Cl, I, Br or F; a = 2.5~12, for example, a can be 2.5, 3, 4, 5, 6, 7, 8, 9, 10, 11 or 12, etc.; b = 0.5~2.5, for example, b can be 0.5, 0.8, 1, 1.2, 1.5, 1.8, 2, 2.3; c = 4~15; d = 0.5~3.5; e = 0.0067~0.2; f = 0.01~0.3, and e:f = 1:(1~1.5).

[0026] Preferably, f = e or 2f = 3e.

[0027] Preferably, the D of the doped sulfide solid electrolyte 50 Particle size ≤15μm, for example, can be 15μm, 14μm, 12μm, 10μm, 9μm, 8μm, 7μm, 6μm, 5μm, 4μm, 3μm, 2μm, 1μm, 0.8μm, 0.5μm, 0.6μm, 0.2μm, 0.1μm, 0.08μm, 0.05μm, 0.03μm or 0.01μm, etc.

[0028] In a second aspect, the present invention provides a method for preparing the doped sulfide solid electrolyte described in the first aspect, the method comprising:

[0029] The basic components of the sulfide solid electrolyte are mixed with the dopant raw materials and subjected to microwave plasma pretreatment to undergo a reduction reaction, resulting in a pretreated material.

[0030] The pre-processed material is ground to generate nanocrystals through mechano-chemical vapor deposition synergistic reaction, thereby obtaining a ground material;

[0031] The ground material is subjected to in-situ densification hot-press sintering to obtain the doped sulfide solid-state electrolyte.

[0032] In the preparation method, the raw material is pre-processed by microwave plasma, the surface oxide of the raw material is reduced by plasma (such as hydrogen plasma), microwave energy simultaneously causes lattice defects of the raw material, and the subsequent reaction activity is improved; then mechano-chemical vapor deposition synergistic reaction occurs in the grinding process to promote the synthesis of nanocrystals; finally, in-situ densification hot-press sintering is adopted to simultaneously realize powder forming, sintering and densification, thereby simplifying the process flow.

[0033] It should be noted that the size of the nanocrystal is in the range of 1-100 nm, the lattice arrangement is regular, the structure is short-range ordered, but surface defects or strain may exist; a large number of grain boundaries exist between the nanocrystals, the grain boundaries are rich, and can affect ion / electron transmission.

[0034] As a preferred technical solution of the present application, the dopant raw material includes an oxide of a metal element A.

[0035] As a preferred technical solution of the present application, the microwave plasma pre-processing is performed in a mixed plasma atmosphere of inert atmosphere.

[0036] Preferably, the inert atmosphere includes Ar (argon).

[0037] Preferably, the power of the microwave plasma pre-processing ranges from 100 to 300 W, for example, 100 W, 150 W, 200 W, 250 W or 300 W; the vacuum degree ranges from 0.01 to 0.1 Pa, for example, 0.01 Pa, 0.02 Pa, 0.04 Pa, 0.06 Pa, 0.08 Pa or 0.1 Pa, etc.; the temperature ranges from 20 to 65℃, for example, 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃ or 65℃, etc.; and the time ranges from 5 to 20 min, for example, 5 min, 10 min, 15 min or 20 min, etc.

[0038] Preferably, the flow rate of the inert atmosphere is 20-50 sccm, for example 20 sccm, 23 sccm, 25 sccm, 28 sccm, 30 sccm, 33 sccm, 35 sccm, 38 sccm, 40 sccm, 42 sccm, 45 sccm, 48 sccm or 50 sccm, etc., to maintain a stable plasma and avoid excessive sputtering; a vacuum of 0.01-0.1 Pa is conducive to ensuring plasma uniformity; the power range is 100-300 W, and too high a power is prone to cause sulfur volatilization or lattice damage; the processing time is 5-20 min, and the temperature is 20-65℃, to prevent thermal decomposition of the raw material.

[0039] As a preferred technical solution of the present application, the grinding includes at least one of ball milling, high-energy vibration milling, jet milling, ultrasonic-assisted grinding or cryogenic grinding.

[0040] The ball milling is performed in a zirconia ball mill jar, and the inner wall of the zirconia ball mill jar is plated with a diamond-like carbon coating.

[0041] Preferably, the rotation speed of the ball mill is 400-700 rpm, for example 400 rpm, 430 rpm, 450 rpm, 480 rpm, 500 rpm, 520 rpm, 550 rpm, 580 rpm, 600 rpm, 620 rpm, 640 rpm, 660 rpm, 680 rpm or 700 rpm, etc.; and a pulse frequency conversion mode is adopted, with an on-off ratio of 10:(5-2), for example 10:5, 10:4, 10:3 or 10:2, etc.

[0042] In the present application, the use of a specially designed zirconia ball mill jar with a diamond-like carbon coating on the inner wall can prevent metal (such as iron) contamination from tools used to scrape materials during the experiment, and the pulse frequency conversion mode can further promote the crystallization of nanocrystals.

[0043] Preferably, the ball milling time is 30 min-12 h, for example 30 min, 40 min, 50 min, 60 min, 1.2 h, 1.5 h, 1.8 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h or 12 h, etc.

[0044] As a preferred technical solution of the present application, the temperature and pressure of the in-situ densification hot-pressing sintering are gradually increased in stages.

[0045] Preferably, the in-situ densification hot-pressing sintering temperature ranges from 50 to 500℃, such as 50℃, 80℃, 100℃, 130℃, 150℃, 180℃, 200℃, 230℃, 250℃, 280℃, 300℃, 330℃, 350℃, 380℃, 400℃, 420℃, 450℃, 480℃ or 500℃, etc.; the pressure ranges from 5 to 300MPa, such as 5MPa, 8MPa, 10MPa, 30MPa, 50MPa, 80MPa, 100MPa, 130MPa, 150MPa, 180MPa, 200MPa, 230MPa, 250MPa, 280MPa or 300MPa, etc.; and the processing time of each stage ranges from 30min to 12h, such as 30min, 45min, 60min (1h), 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h or 12h, etc.

[0046] In the present application, the in-situ densification hot-pressing sintering can realize densification at a lower temperature (50-100℃ lower than the normal pressure sintering), which can effectively reduce the interface side reaction between the positive electrode and the solid electrolyte in subsequent application; increasing the applied pressure while heating (usually 200-400℃) can promote the plastic deformation and diffusion of the particles, and finally make the relative density reach more than 95% (close to the theoretical density). The doped sulfide solid electrolyte after in-situ densification hot-pressing sintering has tight crystal boundary contact, which can significantly reduce the crystal boundary impedance and improve the ionic conductivity.

[0047] Specifically, the normal pressure high temperature sintering (such as 900℃) densification method in the prior art is easy to cause lithium volatilization (such as Li2O, Li2S vaporization), which makes the stoichiometric ratio of the electrolyte deviate (such as the decrease of Li-rich phase), and is easy to cause lithium depletion type side reaction (such as the interface generates high impedance Li2CO3) when contacting with the positive electrode (such as NCM).

[0048] The hot-pressing low-temperature sintering in the application reduces the dependence on temperature, inhibits the interface instability factors induced by high temperature, reduces lithium volatilization and loss and composition segregation, and maintains the chemical uniformity of the electrolyte; second, high-temperature normal-pressure sintering is easy to cause the melting or aggregation of impurities (such as sintering aids Li3BO3 or residual Li2CO3) at the grain boundaries, and these impurities will have side reactions (such as generating Li2O or CO2) with the positive electrode in the battery cycle, while the high temperature and high pressure stress matching of the hot-pressing can inhibit the phase migration of impurities and promote the formation of pure grain boundaries. Therefore, the in-situ densification hot-pressing sintering of the application can optimize the microstructure, reduce the interface defects, reduce the open pores in the electrolyte, avoid the local side reactions of the positive active material (such as Ni-rich NCM) embedded in the pores, reduce the interface contact resistance, and inhibit the lithium dendrite growth caused by uneven current distribution; it is also beneficial to the uniformization of the grain size, avoids the stress concentration at the large grain boundaries leading to cracks, and the problem of accelerated degradation of the positive electrode / electrolyte interface caused thereby.

[0049] Preferably, the preparation method further comprises crushing the obtained doped sulfide solid-state electrolyte to achieve a target particle size.

[0050] In a third aspect, the application provides a positive electrode sheet containing the doped sulfide solid-state electrolyte of the first aspect.

[0051] Preferably, the positive active material in the positive active layer of the positive electrode sheet is pre-lithiated to form a lithium-rich layer on the surface.

[0052] Preferably, the lithium-rich layer comprises a lithium source, and the lithium source comprises at least one of Li2CO3, Li3N, Li2O, Li2TiO3, Li3PO4, AlF6Li3, AlHLiO2, AlCl4Li or Li2O3Ti.

[0053] Preferably, the method for forming the lithium-rich layer comprises mixing and grinding the positive active material with the lithium source, and calcining; the grinding speed is 300-500 rpm, and the grinding time is 0.5-2 h; the calcining temperature is 400-500 ℃, and the calcining time is 1-3 h.

[0054] Preferably, the mass of the lithium-rich layer accounts for 0.1%-1% of the mass of the positive active material, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9% or 1%, etc.

[0055] It should be noted that the application of the doped sulfide solid electrolyte in the battery includes the following mode: the doped sulfide solid electrolyte is directly mixed in the active layer of the positive electrode sheet, and other raw materials in the positive electrode active layer are subjected to mixing, slurry preparation, coating, rolling and other processes. Due to the existence of the space charge layer between the sulfide solid electrolyte and the positive electrode active material (oxide positive electrode), the transmission of lithium ions at the positive electrode / electrolyte interface is hindered, resulting in high interface impedance and polarization. Therefore, further, the application can use other lithium sources to pre-lithiate the positive electrode active material to form a lithium-rich layer, obtain the pre-lithiated positive electrode active material, and then mix the doped sulfide solid electrolyte, which can further reduce the problem of the space charge layer between the sulfide electrolyte and the oxide positive electrode material.

[0056] Specifically, by pre-introducing a lithium-rich layer on the surface of the oxide positive electrode, the loss of lithium ions can be compensated for, the lithium concentration gradient at the interface can be reduced, and the formation of the space charge layer can be inhibited; the interface impedance can be reduced, and the ion transmission efficiency can be improved. After the lithium-rich layer is pre-set, the lithium ion concentration on the surface of the positive electrode is increased, the energy barrier at the interface is reduced, and the lithium ion migration is smoother, thereby improving the rate performance and cycle stability of the all-solid-state battery; the high reactivity of the sulfide electrolyte to the oxide positive electrode can cause interface decomposition (such as oxidation of the sulfide to generate SO Ｘ , Li2S, etc.), further exacerbating the space charge layer effect. The lithium-rich layer can act as a physical / chemical barrier to reduce direct contact between the positive electrode and the electrolyte, inhibit the occurrence of side reactions, and maintain the interface stability; the mechanical property difference between the oxide positive electrode (rigid) and the sulfide electrolyte (soft) can cause poor interface contact. The lithium-rich layer (such as a flexible lithium compound) can fill the interface gap, enhance the interface contact, and simultaneously relieve the volume change stress during charging and discharging; high-voltage oxide positive electrodes (such as high-nickel NCM and lithium-rich materials) are more likely to cause oxidative decomposition of the sulfide electrolyte. The lithium-rich layer can adjust the potential distribution at the interface, delay the breakthrough of the electrochemical window of the electrolyte, and improve the high-voltage compatibility.

[0057] Since it is directly used in the positive electrode active layer, the particle size of the solid electrolyte should match the requirements of the positive electrode active layer. In general, the D 50 particle size of the doped sulfide solid electrolyte is ≤1 μm.

[0058] Preferably, the mass fraction of the doped sulfide solid electrolyte accounts for 1% to 35%, for example, 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 23%, 25%, 28%, 30%, 32% or 35%, etc., based on 100% of the mass of the positive electrode active layer of the positive electrode sheet.

[0059] Preferably, the mass percentage of the positive electrode active material is 70% to 90%, for example 70%, 72%, 76%, 78%, 80%, 82%, 84%, 86%, 88% or 90%, etc., and the mass percentage of the conductive agent is 1% to 5%, for example 1%, 2%, 3%, 4% or 5%, etc., based on 100% of the mass of the positive electrode active layer of the positive electrode sheet. The positive electrode active layer of the all-solid-state battery can not need a binder.

[0060] Preferably, the positive electrode active material (oxide positive electrode) can be a ternary positive electrode material (NCM or NCA), a lithium-rich manganese-based material, lithium iron phosphate, lithium cobaltate, etc.

[0061] In a fourth aspect, the present application provides a battery having the doped sulfide solid electrolyte of the first aspect.

[0062] Of course, the doped sulfide solid electrolyte of the present application can also be prepared into a solid electrolyte film sheet with or without other solid electrolytes or binders, etc., and assembled into a battery through the processes of stacking positive electrode sheets, solid electrolyte film sheets and negative electrode sheets. Generally, the D 50 The particle size is ≤ 15 μm.

[0063] It should be further noted that, due to the limitation of the length and in order to avoid redundancy, the present application does not exhaustively list all the point values within the above numerical range, but is also not limited to the listed values, and other unlisted values within the above numerical range are also applicable.

[0064] Compared with the prior art, the present application has at least the following beneficial effects:

[0065] By doping a specific oxide of A into the base component of the sulfide solid electrolyte, the soft acid element A is more likely to form a covalent bond with the soft base S 2- Preferably, the A-S covalent bond has a higher polarity than the P-S covalent bond, thereby improving the air stability of the sulfide solid electrolyte and effectively inhibiting the hydrolysis of the sulfide electrolyte. Meanwhile, the valence electron layer in the specific electronic arrangement structure of the metal element A is fully filled, which is stable and can effectively improve the oxidation resistance of the sulfide solid electrolyte. Moreover, A has a lower valence state in the doped sulfide solid electrolyte, avoiding the influence of high-valence metal doping elements.

[0066] In the preparation method, the raw material is pre-treated by microwave plasma, the surface oxide of the raw material is reduced by plasma, and the microwave energy also causes lattice defects of the raw material, thereby improving the subsequent reaction activity; then, mechanical chemical vapor deposition and reaction are promoted in the grinding process to promote the synthesis of nanocrystals; finally, in-situ densification hot-pressing sintering is adopted to simultaneously realize powder forming, sintering and densification, thereby simplifying the process flow and ensuring that the obtained doped sulfide solid electrolyte has excellent performance.

[0067] In the present application, the lithium source is used to pre-lithiate the positive electrode active material to form a lithium-rich layer, and the pre-lithiated positive electrode active material is mixed with the doped sulfide solid electrolyte to further reduce the problem of space charge layer of sulfide electrolyte and oxide positive electrode material. DETAILED DESCRIPTION

[0068] The technical solutions of the present application are further illustrated by the specific embodiments.

[0069] Those skilled in the art should understand that the embodiments are only used to help understand the present application, and should not be regarded as specific limitations of the present application.

[0070] Embodiment 1

[0071] The present embodiment provides a doped sulfide solid electrolyte, which comprises a sulfide solid electrolyte base component Li 10 PS 4.5 Cl3Br3, the sulfide solid electrolyte base component contains a dopant Yb2O3, the ratio of the molar amount of the metal element Yb to the molar amount of the sulfide solid electrolyte base component is 0.08:1, and the chemical structural formula of the doped sulfide solid electrolyte is Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 .

[0072] The preparation method of the doped sulfide solid electrolyte comprises:

[0073] The raw materials LiCl, LiBr, P2S5, Li2S, Yb2O3 are weighed according to the molar ratio of 3:3:0.5:2:0.04 and placed in an argon plasma atmosphere, microwave plasma pretreatment is carried out for 10 min, and a pretreated material is obtained; the pretreated material is poured into a zirconia grinding tank (the inner wall is coated with a diamond-like carbon coating) for grinding, mechanical and chemical vapor deposition synergistic reaction occurs, the rotation speed is controlled at 700 rpm, and pulse frequency conversion mode (start-stop ratio of 10:5) is used to promote the formation of nanocrystals, the grinding time is 10 h, and a ground material is obtained; finally, the ground material is subjected to in-situ densification hot-pressing sintering, a gradient heating strategy is adopted, the temperature and pressure are gradually increased with time, 50 MPa is reached at 200 DEG C, 100 MPa is reached at 300 DEG C, and 300 MPa is reached at 400 DEG C, and the hot-pressing holding time of each stage is 4 h, and a doped sulfide solid electrolyte is obtained; then the sand mill is used to grind and crush into two samples with particle sizes of 600 nm and 3 μm respectively for use. 50 The two samples with particle sizes of 600 nm and 3 μm are used for use.

[0074] Example 2

[0075] The present embodiment provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the amount of raw material Yb2O3 is adjusted, so that the doping amount of dopant Yb2O3 in the doped sulfide solid electrolyte changes, and the chemical structural formula of the doped sulfide solid electrolyte is changed from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 to Li 10 PS 4.5 Yb 0.22 Cl3Br3O 0.33 In addition to the above, other conditions are exactly the same as in Example 1.

[0076] Example 3

[0077] The present embodiment provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the amount of raw material Yb2O3 is adjusted, so that the doping amount of dopant Yb2O3 in the doped sulfide solid electrolyte changes, and the chemical structural formula of the doped sulfide solid electrolyte is changed from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 to Li 10 PS 4.5 Yb 0.16 Cl3Br3O 0.24 , in addition to the above, other conditions are exactly the same as in Example 1.

[0078] Example 4

[0079] This example provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the amount of raw material Yb2O3 is adjusted, so that the doping amount of dopant Yb2O3 in the doped sulfide solid electrolyte changes, and the chemical structural formula of the doped sulfide solid electrolyte is Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Yb 0.04 Cl3Br3O 0.06 , except the above, other conditions are exactly the same as example 1.

[0080] Example 5

[0081] This example provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the amount of raw material Yb2O3 is adjusted, so that the doping amount of dopant Yb2O3 in the doped sulfide solid electrolyte changes, and the chemical structural formula of the doped sulfide solid electrolyte is Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Yb 0.01 Cl3Br3O 0.015 , except the above, other conditions are exactly the same as example 1.

[0082] Example 6

[0083] This example provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the amount of raw material Yb2O3 is adjusted, so that the doping amount of dopant Yb2O3 in the doped sulfide solid electrolyte changes, and the chemical structural formula of the doped sulfide solid electrolyte is Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Yb 0.004 Cl3Br3O 0.006 , except the above, other conditions are exactly the same as example 1.

[0084] Example 7

[0085] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to two times of a molar amount of MgO, so that a dopant in the doped sulfide solid electrolyte becomes MgO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Mg 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1.

[0086] Embodiment 8

[0087] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to two times of a molar amount of PdO, so that a dopant in the doped sulfide solid electrolyte becomes PdO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Pd 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1.

[0088] Embodiment 9

[0089] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to two times of a molar amount of ZnO, so that a dopant in the doped sulfide solid electrolyte becomes ZnO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 is adjusted to Li 10 PS 4.5 Zn 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1.

[0090] Embodiment 10

[0091] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to a double molar amount of BaO, so that a dopant in the doped sulfide solid electrolyte becomes BaO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 to Li 10 PS 4.5 Ba 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1 except the above.

[0092] Embodiment 11

[0093] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to a double molar amount of SrO, so that a dopant in the doped sulfide solid electrolyte becomes SrO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 to Li 10 PS 4.5 Sr 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1 except the above.

[0094] Embodiment 12

[0095] The present embodiment provides a doped sulfide solid electrolyte, in a preparation method of the doped sulfide solid electrolyte, a raw material is adjusted from Yb2O3 to a double molar amount of CaO, so that a dopant in the doped sulfide solid electrolyte becomes CaO, and a chemical structural formula of the doped sulfide solid electrolyte is adjusted from Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 to Li 10 PS 4.5 Ca 0.08 Cl3Br3O 0.08 , and other conditions are the same as those in Embodiment 1 except the above.

[0096] Embodiment 13

[0097] The present embodiment provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the raw material Yb2O3 is adjusted to two times the molar amount of BeO, so that the dopant in the doped sulfide solid electrolyte becomes BeO, and the chemical structural formula of the doped sulfide solid electrolyte is adjusted to Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 adjusted to Li 10 PS 4.5 Be 0.08 Cl3Br3O 0.08 , except the above, other conditions are exactly the same as in Example 1.

[0098] Comparative Example 1

[0099] The present comparative example uses the sulfide solid electrolyte base component Li 10 PS 4.5 Cl3Br3 in Example 1 for subsequent testing.

[0100] Comparative Example 2

[0101] The present comparative example provides a doped sulfide solid electrolyte, in the preparation method of the doped sulfide solid electrolyte, the raw material Yb2O3 is adjusted to two times the molar amount of ZrO2, so that the dopant in the doped sulfide solid electrolyte becomes ZrO2, and the chemical structural formula of the doped sulfide solid electrolyte is adjusted to Li 10 PS 4.5 Yb 0.08 Cl3Br3O 0.12 adjusted to Li 10 PS 4.5 Zr 0.08 Cl3Br3O 0.16 , except the above, other conditions are exactly the same as in Example 1.

[0102] Application Example 1

[0103] The present application provides a full solid-state battery, which contains the doped sulfide solid electrolyte provided in any one of Examples 1 to 13 or Comparative Example 2 or contains the sulfide solid electrolyte base component of Comparative Example 1, and the manufacturing and assembly method of the full solid-state battery comprises:

[0104] Preparation of positive electrode mixed powder: lithium nickel cobalt manganese oxide ternary material LiNi 0.9 Co 0.1 Mn 0.1O2, lithium source AlHLiO2 mixed by mass ratio 99:0.5 grinding 1h, the grinding speed is 400rpm, then calcining at 450℃ for 2h, to obtain the calcined material; then the calcined material, and D 50 The doped sulfide solid electrolyte or sulfide solid electrolyte base component with a particle size of 600nm is mixed in a mass ratio of 8:2, and is ground and mixed at 400rpm for 30min to obtain a pre-lithiated positive electrode active material;

[0105] In a glove box, the pre-lithiated positive electrode active material and the conductive agent VGCF (3% of the total mass) are loaded into a grinding tank, zirconium oxide balls with a diameter of 5mm are added, the ball-to-material ratio is 5:1, the tank is tightly screwed after uniform stirring, and the interface of the cover is sealed with tape; the grinding machine is set to rotate at 350rpm for 8min, pause for 2min, reverse for 8min, and a total of 38min; the above grinding tank is symmetrically placed, and the grinding is started after the fixing knob is tightly screwed to obtain a positive electrode mixture powder;

[0106] Preparation of a solid electrolyte layer: the same doped sulfide solid electrolyte or sulfide solid electrolyte base component as in the positive electrode mixing is made into a solid electrolyte layer, 100-120mg of the electrolyte is placed in an alumina ceramic mold inner container (diameter 10mm), and a solid electrolyte sheet is pressed by means of a pressure machine (parameters: 100-130MPa, 30s-2min), and excess solid electrolyte powder is removed by an ear cleaning ball;

[0107] Assembly of a battery: 25mg of the positive electrode mixture powder is placed on the solid electrolyte sheet, a stainless steel electrode pressing head is rotated to the bottom of the mold, and the powder is flattened by rotating the pressing head; the pressing head is removed, a piece of carbon-coated aluminum foil (10mm) is placed above the powder, a pressure machine is used to press at 400MPa for 2min, and excess positive electrode mixture powder is removed by an ear cleaning ball; then the second weighing is performed, and the actual loading amount of the solid electrolyte can be calculated; an indium sheet and a copper-lithium composite strip are sequentially placed on the other side of the solid electrolyte sheet, the indium is opposite to the intermediate electrolyte layer, and the lithium is opposite to the indium, both with a diameter of 10mm; finally, the mold and the pressing head are buckled, and the nut is tightened, and a full-solid-state mold battery is obtained.

[0108] Application Example 2

[0109] The application provides a full-solid-state battery containing the doped sulfide solid electrolyte provided in Example 1, and in the manufacturing and assembling method of the full-solid-state battery, the lithium source is not used when the positive electrode mixture powder is prepared, the lithium nickel cobalt manganese oxide ternary material is directly mixed with the doped sulfide solid electrolyte,

[0110] In addition to the above, other conditions are exactly the same as in Application Example 1.

[0111] Application Control Group 1

[0112] The application example 1 is completely same with application example 1 except that the positive electrode mixed powder of the application example does not contain the doped sulfide solid electrolyte or the sulfide solid electrolyte base component, and the doped sulfide solid electrolyte of example 1 is used in the solid electrolyte layer.

[0113] Characterization and test:

[0114] I. The solid electrolytes obtained in examples 1 to 13 and comparative examples 1 and 2 are tested as follows:

[0115] (1) Air stability test:

[0116] A1, start the dehumidifier environment, and wait for the environment to be stable below-45℃ for at least half an hour;

[0117] A2, electrolyte exposure: spread the dried weighing paper on the test table, and press a weight on the four corners to prevent the weighing paper from blowing away; take 0.5±0.03g of electrolyte and spread it on the weighing paper, and use a medicine spoon to spread it to a thickness of 1±0.3mm, and collect the material after standing for 4.5h;

[0118] A3, take 120~130mg of solid electrolyte powder and put it into the inner container of the mold (diameter 10mm), and press it into an electrolyte sheet by means of a pressure machine (parameters: 400MPa), and match stainless steel blocking electrodes at both ends of the electrolyte sheet;

[0119] A4, use an electrochemical workstation to test the impedance value of the sample by electrochemical impedance, and obtain the resistance value R (Ω) of the solid electrolyte, wherein the test frequency is 0.01MHz to 1MHz, the test disturbance voltage is 15mV, and the test temperature is the temperature in the glove box;

[0120] A5, take out the electrolyte sheet, and use a micrometer to measure the thickness L (cm) of the solid electrolyte;

[0121] A6, then calculate the ionic conductivity σ of the solid electrolyte at the temperature in the glove box by the formula σ=L / (R·S); in the formula: σ-the ionic conductivity of the solid electrolyte (S·cm -1 ); L-the thickness of the solid electrolyte (cm); R-the intrinsic resistance of the solid electrolyte (Ω); S-the cross-sectional area of the solid electrolyte (cm 2 );

[0122] A7, test the conductivity of the solid electrolyte before and after exposure according to the procedures of steps A3~A6, and calculate the air stability of the solid electrolyte by the formula: air stability=pre-exposure conductivity / post-exposure conductivity×100%.

[0123] (2) Electrochemical window test of antioxidant capacity:

[0124] B1, 100 mg of total material was weighed according to the mass ratio of conductive agent VGCF:sulfide solid-state electrolyte = 20:80, placed in a mortar, and hand-ground for 10 min to obtain a mixture;

[0125] B2, 100 mg of sulfide solid-state electrolyte powder was weighed into a mold inner container (diameter 10 mm), and a pressure machine (parameters: 400 MPa) was used to press the electrolyte sheet;

[0126] B3, 25 mg of the mixture in step (1) was laid on one end of the electrolyte sheet, and the mold was flattened, and then a pressure machine (parameters: 400 MPa) was used to compact it; a Li sheet was introduced at the other end; an electrochemical workstation was used to perform LSV test, with open-circuit voltage set to 6 V and scan rate set to 0.1 mV / S, to obtain the oxidation window (unit: V).

[0127] II. The batteries obtained in application example 1 and application control group 1 were tested as follows:

[0128] (1) 0.1C initial coulombic efficiency: at 35±3℃, 0.1C constant current charging to 3.7V, constant voltage charging to 3.7V until the cutoff current is 0.05C, to obtain the first 0.1C charging capacity A1; then 0.1C constant current discharging, discharging the battery to 2.0V, to obtain the first 0.1C discharging capacity A2; the initial efficiency = A2 / A1*100%.

[0129] (2) 0.1C / 0.5C discharging capacity test: at 35±3℃, 0.1C / 0.5C constant current charging to 3.7V, constant voltage charging to 3.7V until the cutoff current is 0.05C; then 0.1C / 0.5C constant current discharging, discharging the battery to 2.0V, to obtain the 0.1C / 0.5C discharging capacity.

[0130] (3) Test method of 0.5C / 0.5C capacity retention rate: at 35±3℃, 0.5C constant current charging to 3.7V, constant voltage charging to 3.7V until the cutoff current is 0.05C, 0.5C discharging the battery to 2.0V, the first 0.5C discharging capacity is recorded as D1; repeating the charging and discharging steps N times, obtaining the Nth discharging capacity recorded as DN, calculating the Nth capacity retention rate according to the first discharging capacity and the Nth discharging capacity, the Nth capacity retention rate = (DN / D1) * 100%.

[0131] The test results are shown in Table 1.

[0132] Table 1

[0133]

[0134] As can be seen from Table 1:

[0135] Comparing Examples 1 to 6, the doping amount of metal element A in Example 2 is too much, although the air stability is improved, but the metal element is too much, the electrolyte electronic conductivity is too high, the high electronic conductivity will cause the formation of an electron conduction path inside the electrolyte, causing the battery to self-discharge, and thus reducing the capacity retention rate; at the same time, the electron directly participates in the side reaction (such as electrolyte reduction), consumes active lithium ions, resulting in reduced charge-discharge efficiency; high electronic conductivity will exacerbate the redox reaction between the electrolyte and the electrode (such as high-voltage positive electrode), forming an interface decomposition layer (such as Li2S), increasing the interface impedance, and too high electronic conductivity will also seriously damage the electrochemical stability and cycle life of the battery. However, the doping amount of metal element A is too small, which is not enough to produce an optimal effect, such as Example 6, so the performance difference is large. Comparing Example 1 with Examples 7 to 13, in addition to Yb, other metal elements A can also play a role in the appropriate doping amount to improve air stability, with Yb being the best. Comparing Example 1 with Comparative Example 1 and Comparative Example 2, it can be found that the air stability and cycle performance are poor when no metal element A is doped or replaced by a high-valence metal element.

[0136] Comparing the battery containing the sulfide solid electrolyte of Example 1 in Application Example 1 with Application Example 2, it can be found that the formation of a lithium-rich layer on the positive electrode active material can effectively improve the problem of the space charge layer of the sulfide electrolyte and the oxide positive electrode material, thereby effectively improving the battery performance.

[0137] As can be seen from the above, by doping a specific oxide of A in the base component of the sulfide solid electrolyte, the soft acid element A is more likely to form a covalent bond with the soft base S 2- Preferentially combined to replace P to form an A-S covalent bond with higher polarity than P-S, thereby improving the air stability of the sulfide solid electrolyte and effectively inhibiting the hydrolysis of the sulfide electrolyte; at the same time, the valence electron layer in the specific electronic arrangement structure of the metal element A is fully filled, which is stable and can effectively improve the oxidation resistance of the sulfide solid electrolyte. And A in the doped sulfide solid electrolyte presents a lower valence state, avoiding the influence of high-valence metal doping elements. The present application further uses a lithium source to pre-lithiate the positive electrode active material to form a lithium-rich layer, and then mixes the pre-lithiated positive electrode active material with the doped sulfide solid electrolyte of the present application, which can further reduce the problem of the space charge layer of the sulfide electrolyte and the oxide positive electrode material.

[0138] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the specific details of the above-described embodiments, and various simple modifications can be made to the technical solutions of the present application within the technical concept of the present application, and these simple modifications all belong to the protection scope of the present application.

[0139] In addition, it should be noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0140] In addition, various different embodiments of the present application can also be combined in any manner, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

Claims

1. A doped sulfide solid-state electrolyte, characterized by, The sulfide solid electrolyte base component contains a dopant, and the dopant contains an oxide of a metal element A; the valence electron shell of the metal element A is fully filled, and the A is a soft acid element; The valence state of the A in the doped sulfide solid electrolyte is not more than +3; The sulfide solid electrolyte base component is an Argyrodite series electrolyte; the metal element A includes at least one of Zn, Pd or Yb; the ratio of the molar amount of the metal element A to the molar amount of the sulfide solid electrolyte base component is (0.01~0.2):1; the chemical structural formula of the doped sulfide solid electrolyte includes Li a P b S c A e X d O f , wherein X includes at least one of Cl, I, Br or F; a=2.5~12, b=0.5~2.5, c=4~15, d=0.5~3.5, e=0.0067~0.2, f=0.01~0.3; and e:f=1:(1~1.5); The doped sulfide solid electrolyte is prepared by a preparation method, and the preparation method comprises: The sulfide solid electrolyte base component raw material and the dopant raw material are mixed, microwave plasma pretreatment is performed, a reduction reaction occurs, and a pretreated material is obtained; The pretreated material is ground, a mechano-chemical vapor deposition synergistic reaction occurs, nanocrystals are generated, and a ground material is obtained; The ground material is subjected to in-situ densification hot-pressing sintering to obtain the doped sulfide solid electrolyte.

2. The doped sulfide solid-state electrolyte of claim 1, wherein, D of the doped sulfide solid-state electrolyte 50 Particle size ≤ 15 μm.

3. A method for producing the doped sulfide solid electrolyte according to claim 1 or 2, characterized by, The preparation method comprises: The sulfide solid electrolyte base component raw material and the dopant raw material are mixed, microwave plasma pretreatment is performed, a reduction reaction occurs, and a pretreated material is obtained; The pretreated material is ground, a mechano-chemical vapor deposition synergistic reaction occurs, nanocrystals are generated, and a ground material is obtained; The ground material is subjected to in-situ densification hot-pressing sintering to obtain the doped sulfide solid electrolyte.

4. The method of claim 3, wherein the method is characterized by, The dopant raw material contains an oxide of a metal element A.

5. The method of claim 3, wherein the method further comprises a step of adding a dopant to the molten salt. The microwave plasma pretreatment is performed in a plasma atmosphere of an inert atmosphere; the inert atmosphere contains Ar; And / or, the microwave plasma pretreatment has a power range of 100-300 W, a vacuum degree of 0.01-0.1 Pa, a temperature of 20-65 ℃, and a time of 5-20 min.

6. The method of claim 3, wherein the method further comprises: The grinding comprises at least one of ball milling, high-energy vibration milling, jet milling, ultrasonic-assisted grinding, or cryogenic grinding; The ball milling is performed in a zirconia ball milling tank, the inner wall of the zirconia ball milling tank is coated with a diamond-like carbon coating, and / or the ball milling has a rotation speed of 400-700 rpm and adopts a pulse frequency conversion mode with an on-off ratio of 10:(5-2); and / or the ball milling has a time of 30 min-12 h.

7. The method of claim 3, wherein the method further comprises a step of adding a dopant to the molten salt. The temperature and pressure of the in-situ densification hot-pressing sintering are both gradually increased; And / or, the in-situ densification hot-pressing sintering has a temperature range of 50-500 ℃ and a pressure range of 5-300 MPa, and each stage has a processing time of 30 min-12 h.

8. A positive electrode sheet characterized by comprising: The positive electrode sheet contains the doped sulfide solid electrolyte of claim 1 or 2.

9. The positive electrode sheet according to claim 8, characterized by The positive electrode sheet satisfies at least one of the following conditions: 1) The positive electrode active layer of the positive electrode sheet contains the doped sulfide solid electrolyte; 2) The positive electrode active material in the positive electrode active layer of the positive electrode sheet is pre-lithiated, and a lithium-rich layer is formed on the surface; And / or, the lithium-rich layer contains at least one of Li2CO3, Li3N, Li2O, Li2TiO3, Li3PO4, AlF6Li3, AlHLiO2, AlCl4Li, or Li2O3Ti; And / or, the mass of the lithium-rich layer accounts for 0.1%-1% of the mass of the positive electrode active material; 3) The mass ratio of the doped sulfide solid-state electrolyte is 1% to 35%, the mass ratio of the positive electrode active material is 70% to 90%, and the mass ratio of the conductive agent is 1% to 5%, based on 100% of the mass of the positive electrode active layer of the positive electrode sheet; 4) In the positive electrode active layer of the positive electrode sheet, the positive electrode active material includes at least one of nickel-cobalt-manganese ternary material, nickel-cobalt-aluminum ternary material, lithium-rich manganese-based material, lithium iron phosphate, or lithium cobaltate.

10. A battery, characterized by The doped sulfide solid-state electrolyte of claim 1 or 2 or the positive electrode sheet of claim 8 or 9.

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