Solid electrolyte and secondary battery containing the solid electrolyte

Abstract

A solid electrolyte and a secondary battery containing the solid electrolyte are provided. The solid electrolyte contains or consists of core-shell particles, wherein the core of the core-shell particles contains or consists of a solid electrolyte material suitable for chemical reaction with metallic lithium. The solid electrolyte is characterized in that the shell of the core-shell particles contains or consists of a glass containing or consisting of Li₂S-P₂S₅-P₂O₅, and / or a glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅. When used in a secondary battery, the solid electrolyte enables a more stable long-term prevention of chemical reaction with electrode materials of the secondary battery, such as metallic lithium, reducing the risk of dendrite growth and increasing cycle stability.Furthermore, the solid electrolyte according to the invention exhibits a high ionic conductivity for lithium ions and a low electronic conductivity.

Description

[0001] A solid electrolyte and a secondary battery containing the solid electrolyte are provided. The solid electrolyte contains or consists of core-shell particles, wherein the core of the core-shell particles contains or consists of a solid electrolyte material suitable for chemical reaction with metallic lithium. The solid electrolyte is characterized in that the shell of the core-shell particles contains or consists of a glass containing or consisting of Li₂S-P₂S₅-P₂O₅, and / or contains or consists of a glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₃. When used in a secondary battery, the solid electrolyte enables a more stable long-term prevention of chemical reaction with electrode materials of the secondary battery, such as metallic lithium, reducing the risk of dendrite growth and increasing cycle stability.Furthermore, the solid electrolyte according to the invention exhibits a high ionic conductivity for lithium ions and a low electronic conductivity.

[0002] Many of the solid electrolytes known in the art (e.g., of the argyrodite type such as Li6PS5Cl) are considered promising for solid-state batteries due to their ionic conductivity, which is comparable to that of liquid electrolytes. However, such solid electrolytes can exhibit chemical reactivity towards promising electrode materials for secondary batteries (such as metallic lithium for an anode and / or lithium nickel cobalt manganese oxide for a cathode), which complicates their use in secondary batteries with such electrode materials or makes it possible only by accepting significant disadvantages. For example, the ionic conductivity at the interface between the solid electrolyte and the electrode material can decrease (increase in interfacial impedance), and mechanical damage to the solid electrolyte (e.g., pore formation and / or cracking) can occur, leading to a risk of increased dendrite formation (e.g.,consists of lithium dendrite formation) and electrical short circuits.

[0003] It is known in the prior art to coat Li6PS5Cl particles with a Li3OCl coating to increase the stability of the resulting core-shell particle against metallic lithium. The Li3OCl coating provides the Li6PS5Cl core with some protection against chemical reaction with the metallic lithium of the anode and the lithium nickel cobalt manganese oxide of the cathode. Furthermore, the Li3OCl coating has been observed to suppress lithium dendrite growth and improve cycle stability (Zhang et al., “Synergistic Li6PS5Cl@Li3OCl composite electrolyte for high-performance all-solid-state lithium batteries”, Green Energy & Environment, 10:793-803).However, the disadvantage of a casing made of Li3OCl is that Li3OCl reacts with metallic lithium over time to form Li2O + LiCI, which means that the long-term stability of such a solid electrolyte when used in a secondary battery with a lithium anode is in need of improvement.

[0004] Based on this, the object of the present invention was to provide a solid electrolyte that overcomes at least one disadvantage known in the prior art. In particular, the solid electrolyte should make it possible, when used in a secondary battery, to prevent chemical reactions with electrode materials (e.g., metallic lithium) in a more stable manner over the long term, to reduce the risk of dendrite growth (e.g., lithium dendrite growth), and / or to increase the cycle life of the secondary battery. Preferably, the solid electrolyte should exhibit the highest possible ionic conductivity for lithium ions and the lowest possible electronic conductivity.

[0005] The problem is solved by the solid electrolyte with the features of claim 1, the secondary battery with the features of claim 10. The dependent claims describe advantageous further developments.

[0006] According to the invention, a solid electrolyte containing core-shell particles, or consisting thereof, is provided. wherein the core of the core-shell particle contains or consists of a solid electrolyte material suitable for chemical reaction with metallic lithium, characterized by the fact that the shell of the core-shell particles i) contains or consists of a glass containing or consisting of Li2S-P2S5-P2O5, or ii) contains or consists of a glass ceramic containing or consisting of Li2S-P2S5-P2O5.

[0007] When used in a secondary battery, the solid electrolyte according to the invention enables a more stable long-term prevention of chemical reactions with electrode materials (e.g., metallic lithium), reduces the risk of lithium dendrite growth, and increases the cycle life of the secondary battery. Furthermore, the solid electrolyte according to the invention exhibits maximum ionic conductivity for lithium ions with minimal electronic conductivity.

[0008] A primary reason for these advantages is that the coating of the solid electrolyte cores with glass and / or glass-ceramic is more homogeneous and continuous (i.e., denser in terms of surface wetting) compared to the known coating of the solid electrolyte cores with the crystalline material Li3OCl (antiperovskite structure), and thus exhibits fewer or no exposed areas (e.g., pores or cracks) where the solid electrolyte material remains exposed. This is because—unlike when using a crystalline material such as Li3OCl—the coating or shell is not polycrystalline and therefore less or not at all granular, thus reducing or completely eliminating the occurrence of grain boundaries with local pores.The more homogeneous, continuous, and denser, even pore-free, coating made possible by the glass and / or glass-ceramic reduces the tendency for the solid electrolyte material of the core to react with electrode materials (such as metallic lithium). This also results in lower electronic conductivity for electrons, which in turn reduces self-discharge and increases cycle life when the solid electrolyte is used in a secondary battery. Furthermore, another advantage of the more homogeneous, continuous, and denser, even pore-free, coating is that the current density is leveled when the solid electrolyte is used in a secondary battery, and—unlike with crystalline Li3OCl—there are no grain pathways that would provide space for the formation of lithium dendrites.This results in the additional advantage of a low susceptibility to the formation of lithium dendrites, which in turn also increases cycle stability and long-term stability.

[0009] A second reason for these advantages is that the glass and / or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅ is chemically more resistant to anode materials (such as metallic lithium) than Li₃OCl. For example, Li₃OCl reacts with metallic lithium over time to form Li₂O and LiCl, which reduces the long-term stability of known core-shell particles with a Li₃OCl coating. In contrast, a glass and / or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅ is relatively more chemically stable against metallic lithium. Furthermore, due to the oxide component of P₂O₅, such a glass and glass-ceramic is also chemically more stable against metallic lithium than a glass or glass-ceramic consisting of Li₂₅-P₂P₅, which lacks an oxide component of P₂O₅.This is because the P₂O₅ component, upon contact with metallic lithium, forms a compact, passivating, SEI-like layer more quickly. This layer is less porous, retains very good ionic conductivity for lithium ions, and exhibits low electronic conductivity. It also shows reactivity towards easily oxidizable cathode materials (such as BS). 2- and / or polysulfides) is reduced in a glass or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅ compared to glasses and glass-ceramics consisting of Li₂S-P₂S₅ and to LiOCl₃. This also increases the long-term stability of the solid electrolyte according to the invention when used in a secondary battery (e.g., in an alkali metal-sulfur battery).

[0010] A third reason for these advantages is that a glass and / or glass-ceramic containing or consisting of Li2S-P2S5-P2O5 not only has a relatively high ionic conductivity for lithium ions (10 -5 up to 10 -2 S / cm at 25 °C) but also has a relatively low electrical conductivity (10 -14 up to 10 -10 S / cm at 25 °C), which, when the solid electrolyte is used in a secondary battery, not only enables very high charging and discharging currents, results in less heat generation and increases energy efficiency, but also ensures a lower tendency to self-discharge and results in high cycle stability.

[0011] A fourth reason for these advantages is that a glass and / or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅ is relatively stable compared to sulfide solid electrolytes (such as Li₆PS₅Cl), since it is a phase-related system with similar chemistry. In contrast, Li₃OCl, used in the prior art as a shell material for sulfide solid electrolyte cores, can release reactive ions (e.g., O₂). 2- -ions) which can chemically attack and decompose a sulfide solid electrolyte (such as Li6PS5Cl). This attack degrades the ionic conductivity for lithium ions and also the interfacial stability of such known core-shell particles over time. This problem is significantly reduced or even eliminated in glass and / or glass-ceramics containing or composed of Li2S-P2S5-P2O5.

[0012] In a preferred embodiment, the glass and glass-ceramic of the shell contain no chalcogenides capable of forming an alloy with metallic lithium, no metalloid compound capable of being reduced by metallic lithium, and no metal compound capable of being reduced by metallic lithium. This further ensures that contact between the solid electrolyte and metallic lithium does not result in any chemical reactions that could damage the protective shell of the core-shell particles, for example, by disrupting the mechanical integrity of the shell (e.g., through cracking and / or volume changes), reducing the stable lithium-ion conductivity of the shell, and / or causing an undesirable increase in the electronic conductivity of the shell. For example, the glass and glass-ceramic contain no tellurium (Te), selenium (Se), germanium (Ge), or antimony (Sb).Furthermore, the glass and glass-ceramic do not contain, for example, PbO, PbF2, Sb2O3, MoO3, B2O3, V2O5, ZrO2, ZrF4 and SnO.

[0013] In a further preferred embodiment, the solid electrolyte material suitable for chemical reaction with metallic lithium comprises or consists of a solid electrolyte material of a type selected from the group consisting of argyrodite type, thio-LISICON type, LGPS type, chloride-doped thiophosphate type, LLZO type, NASICON type, LLTO type, halide type, antiperovskite type, and combinations thereof. Preferably, the solid electrolyte material suitable for chemical reaction with metallic lithium is selected from the group consisting of Li7Ge3PS. 12 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li6PS5Cl, Li6PS5Br, Li3PS4, Li7La3Zr2O 12 , Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge2-x (PO4)3, La 2 / 3-x Li 3x TiO3, Li3YCl6, Li3InCl6, Li 3-3x SC x Sb and combinations thereof. The advantage of these solid electrolyte materials is that their ionic conductivity for lithium ions (C) is particularly high (e.g., in the range of 10). -3 up to 42·10 -2 S / cm at 25 °C).

[0014] The glass and / or glass-ceramic of the core-shell particle shell can contain 40 to 80 mol% Li₂S, preferably 50 to 76 mol% Li₂S, and particularly preferably 60 to 70 wt% Li₂S, based on the total molar mass of the shell. The advantage here is that the shell exhibits a comparatively high ionic conductivity for lithium ions due to the Li₂S content in these regions, without the glass-forming and / or glass-ceramic formation properties being negatively affected by an excessively high Li₂S content. If the glass and / or glass-ceramic contains other components, the glass and / or glass-ceramic of the core-shell particle shell preferably contains (only) 40 to 50 mol% Li₂S based on the total molar mass of the shell.

[0015] Furthermore, the glass and / or glass-ceramic of the core-shell particle shell can contain 19 to 35 mol% P₂S₅, preferably 22 to 30 mol% P₂S₅, and particularly preferably 26 to 30 mol% P₂S₅, based on the total molar mass of the shell. The advantage of a P₂S₅ content in these ranges is that it promotes glass formation and provides high mechanical robustness and lithium solubility. In addition, the shell of the core-shell particles exhibits relatively high chemical stability (interfacial stability) towards electrode materials (such as metallic lithium). If the glass and / or glass-ceramic of the core-shell particle contains other components, it preferably contains (only) 19 to 30 mol% P₂S₅ based on the total molar mass of the shell.

[0016] Furthermore, the glass and / or glass-ceramic of the core-shell particle shell can contain 1 to 15 mol% P₂O₅, particularly preferably 2 to 10 mol% P₂O₅, and particularly preferably 4 to 5 mol% P₂O₅, based on the total molar mass of the shell. The advantage of a P₂O₅ content in these ranges is that the electronic conductivity is lower without (significantly) impairing the ionic conductivity of the core-shell particles. This further reduces the tendency for self-discharge and increases the cycle life when the solid electrolyte is used in a secondary battery. For example, even a P₂O₅ content of 1 to 2 mol% can result in an electronic conductivity that is up to 10 times lower (from approximately 10⁻⁵). -11 up to 10 -13 S / cm) are present, while the ionic conductivity for lithium ions is approximately the same (at about 10 -4 up to 10 -2S / cm) remains. At a P2O5 content of 2 to 5 mol%, the electronic conductivity can be up to 100 times lower (from approximately <10 Ω). -14 S / cm), while the ionic conductivity for lithium ions increases by only a factor of 10 (to approximately 10). -4 up to 10 -5S / cm) deteriorates. While an even higher P₂O₅ content (5 to 15 mol%) can (slightly) further reduce the ionic conductivity, this is acceptable compared to the resulting increase in electronic conductivity. This is especially true since the thickness of the core-shell particle shell can be relatively small, meaning that a decrease in ionic conductivity over the entire conduction path may be less significant than the benefit associated with the increased electronic conductivity. Another crucial advantage is that the chemical resistance to metallic lithium increases with the higher the P₂O₅ content in the glass and / or glass-ceramic, with a P₂O₅ content of just 1 mol% already resulting in a significant improvement in chemical resistance to metallic lithium.Furthermore, the presence of P₂O₅ in these areas leads only to a relatively small increase in the glass transition temperature, so that the cores of the core-shell particles can still be coated with a glass shell at a gently low temperature (approximately in the range of 190 to 250 °C for a short time followed by rapid cooling) and / or with a glass-ceramic shell (approximately in the range of 190 to 300 °C for 1 to 6 hours). If the glass and / or glass-ceramic of the core-shell particles contains other components, the glass and / or glass-ceramic of the shell of the core-shell particles preferably contains (only) 1 to 3 mol% P₂O₅, based on the total molar mass of the shell.

[0017] Furthermore, the glass and / or glass-ceramic shell of the core-shell particles can contain Li₂O as an additional component, preferably 1 to 15 mol% Li₂O, and particularly preferably 2 to 10 mol% Li₂O, based on the total molar mass of the shell. The presence of Li₂O, especially in the specified concentration ranges, improves the resistance to (atmospheric) moisture of the glass and / or the glass-ceramic shell and, in the case of the glass-ceramic, has a particularly beneficial effect on the ionic conductivity for lithium ions (an increase of up to a factor of 10 is possible). Moreover, the proportion of Li₂O in this range leads only to a slight increase in the glass transition temperature, so that the cores of the core-shell particles can still be coated with a glass shell and / or a glass-ceramic shell at a gently low temperature.

[0018] Apart from this, the glass and / or glass-ceramic of the core-shell particle shell can contain Li3N as a further component, preferably 1 to 5 mol% Li3N, particularly preferably 2 to 4 mol% Li3N, with respect to the total molar mass of the shell. The presence of Li3N, especially in the specified concentration range, also has a beneficial effect on the ionic conductivity for lithium ions, since the concentration of mobile charge carriers (lithium ions) is increased and N 3-It is highly polarizable, which stabilizes mobile, "soft" environments. For example, the ionic conductivity can increase by up to a factor of 5 with its presence in these areas. Furthermore, the chemical resistance to metallic lithium is increased. The glass transition temperature rises only slightly, so the cores of the core-shell particles can still be coated with a glass shell and / or a glass-ceramic shell at a gently low temperature.

[0019] Furthermore, the glass and / or glass-ceramic of the core-shell particle shell can contain LiY as an additional component, preferably 5 to 20 mol% LiY, particularly preferably 8 to 15 mol%, based on the total molar mass of the shell, where Y = Cl, Br, or I. The presence of LiX, especially in the specified concentration range, also has a beneficial effect on the ionic conductivity for lithium ions, as LiY increases the lithium ion mobility and provides "fast pathways" for lithium ions. Another advantage is that the glass transition temperature decreases proportionally to the proportion of LiX (approximately 2 K per mol% for LiCl), i.e., the higher the proportion of LiX, the lower the glass transition temperature.This can be advantageous when coating cores of highly temperature-sensitive solid electrolyte materials, as the annealing process for coating formation can be performed at lower temperatures, thereby reducing or even eliminating the risk of damage to the core's solid electrolyte material. Furthermore, the presence of LiY can compensate for an undesirable increase in the glass transition temperature caused, for example, by the possible components Li₂O and / or Li₃N.

[0020] The core of the core-shell particle can have a mean diameter D 50 in the range of 1 to 20 µm, preferably 1.5 to 10 µm, particularly preferably 2 to 5 µm, wherein the mean diameter is particularly related to a mean diameter D measured by laser diffraction 50 refers to a mean diameter D. 50In this area, it has proven advantageous to generate a high packing density of the core-shell particles (i.e., the smallest possible free space volume) and, on the other hand, to maximize the ion conduction distance through the core compared to the ion conduction distance through the shell. The high possible packing density combined with a simultaneously high relative core ion conduction distance allows for maximum ionic conductivity for lithium ions.

[0021] The shell of the core-shell particles can have a thickness, in one direction along a radius of the core-shell particles, in the range of 1 nm to 100 nm, preferably 2 nm to 50 nm, particularly preferably 5 nm to 30 nm, and especially 10 nm to 20 nm, wherein the thickness refers in particular to a thickness measured by transmission electron microscopy. A thickness in this range is advantageous in order to, on the one hand, adequately protect the solid electrolyte material from reaction with electrode material (e.g., lithium) by means of a certain minimum thickness, and on the other hand, to minimize the reduction of the ionic conductivity of the core, which may be higher than the ionic conductivity of the shell, by means of a certain maximum thickness.

[0022] Furthermore, the shell of the core-shell particles can contain the glass and / or glass-ceramic in a weight fraction in the range of 0.5 to 5 wt.%, preferably 1.0 to 4 wt.%, particularly preferably 1.5 to 3 wt.%, and especially 2 to 2.5 wt.%, with respect to the total weight of the core and shell. A weight fraction in this range is advantageous in order to, on the one hand, adequately protect the solid electrolyte material from reaction with electrode material (e.g., lithium) and, on the other hand, to provide the highest possible ionic conductivity for lithium ions with a minimal weight contribution from the shell of the core-shell particles.

[0023] The solid electrolyte can contain a polymeric binder. In this case, the core-shell particles of the solid electrolyte can be held together by the polymeric binder. The solid electrolyte can also be formed as a free-standing film.

[0024] The polymeric binder may contain or consist of a polymer selected from the group consisting of polyethylene oxide, polyethylene oxide copolymer, polyacrylate, polymethacrylate, polydopamine, PTFE, PVDF, polyvinylidene fluoride copolytrifluoroethylene, fluorinated polysiloxane and combinations thereof.

[0025] The polymeric binder may further contain a conducting salt, preferably LiTFSI. The presence of the conducting salt increases the ionic conductivity for lithium ions of the solid electrolyte.

[0026] Furthermore, the polymeric binder can be present in the solid electrolyte at a minimum of 0.1 wt.%, preferably at least 0.5 wt.%, based on the total weight of the solid electrolyte. These lower limits are advantageous to ensure the mechanical stability of the solid electrolyte. For example, the solid electrolyte can be configured as a free-standing film.

[0027] Furthermore, the polymeric binder can be present in the solid electrolyte at a maximum of 5 wt.%, preferably a maximum of 4 wt.%, particularly preferably a maximum of 3 wt.%, most preferably a maximum of 2 wt.%, particularly a maximum of 1 wt.%, and optionally a maximum of 0.5 wt.%. These upper limits are advantageous in order to provide the highest possible ionic conductivity, since any potentially reducing contribution of the polymeric binder to the overall ionic conductivity of the solid electrolyte becomes increasingly negligible with decreasing proportion of the polymeric binder.

[0028] In a preferred embodiment, the polymeric binder is present at least partially, and preferably completely, in the form of fibrils. The advantage is that even small amounts of binder can ensure a sufficiently high bonding effect and thus the mechanical strength of the solid electrolyte. Furthermore, the low proportion of polymeric binder results in a higher overall ionic conductivity for lithium ions and an increased power-to-weight ratio (i.e., power per unit mass). The solid electrolyte can be formed as a free-standing film containing the core-shell particles (preferably uniformly distributed).

[0029] The core-shell particles of the solid electrolyte, preferably the entire solid electrolyte, can exhibit an electronic conductivity (i.e., an electrical conductivity for electrons) in the range of ≤ 10 -9 S / cm, preferably ≤ 10 -10 S / cm, especially preferred ≤ 10 -11 S / cm, especially ≤ 10 -12S / cm. The lower the electronic conductivity, the more the tendency for self-discharge of the secondary battery is reduced and the cycle stability of the secondary battery is increased when the solid electrolyte is used in the battery. Electronic conductivity in these areas is provided by the shell of the core-shell particles, as the shell contains or consists of a glass and / or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅. Such glasses and glass-ceramics have a relatively low electronic conductivity (10 -14 up to 10 -10 S / cm at 25 °C).

[0030] Furthermore, the core-shell particles of the solid electrolyte, preferably the entire solid electrolyte, can exhibit an ionic conductivity for lithium ions in the range of ≥ 10 4 S / cm, preferably ≥ 10 -3 S / cm, especially preferred ≥ 5·10 -3 S / cm, especially ≥ 10 -2S / cm. The higher the ionic conductivity for lithium ions, the greater the maximum possible charging and discharging currents when using the solid electrolyte in a secondary battery. Furthermore, the tendency for lithium dendrite formation is reduced, and cycle life is improved. Ionic conductivity in these ranges is provided, on the one hand, by the shell of the core-shell particles of the solid electrolyte, which contains or consists of a glass and / or glass-ceramic containing or consisting of Li₂S-P₂S₅-P₂O₅. Such glasses and glass-ceramics have a relatively high ionic conductivity (10 -5 up to 10 -2 S / cm at 25 °C). Furthermore, the solid electrolyte material of the core of the core-shell particles can exhibit very high ionic conductivity (e.g., in the range of 10). -3 up to over 10 -2S / cm at 25 °C, if the solid electrolyte material is of the argyrodite type, thio-LISICON type, LGPS type, chloride-doped thiophosphate type, LLZO type, NASICON type, LLTO type, halide type and / or antiperovskite type). The total ionic conductivity resulting from the combination of the solid electrolyte cores with the glass or glass-ceramic shell can therefore be very high (≥ 10 -4 up to ≥ 10 -2 S / cm at 25 °C), especially when the thickness of the shell is small compared to the diameter of the core of the core-shell particles (e.g., by a factor of 10 to 1000).

[0031] The core-shell particles of the solid electrolyte can be arranged in a layer that optionally contains a binder. The layer can be formed as a free-standing film.

[0032] If the core-shell particles are contained within a single layer, the layer can have a thickness of at least 1 µm. This lower limit can be advantageous to ensure a certain minimum distance between the anode and cathode of a secondary battery, thus reducing the risk of electrical short circuits.

[0033] If the core-shell particles are present in a layer, the layer can furthermore have a visible thickness of a maximum of 100 µm, preferably a maximum of 80 µm, particularly preferably a maximum of 60 µm, most preferably a maximum of 40 µm, particularly a maximum of 20 µm, and optionally a maximum of 10 µm. The smaller the layer thickness, the higher the power-to-weight ratio (i.e., the power per unit mass) of a secondary battery that incorporates the solid electrolyte layer. This is a significant advantage, especially in automotive engineering (e.g., electric cars, motorcycles, and / or aircraft), as less overall mass needs to be moved, thus enabling greater driving ranges for the vehicles or aircraft with a given secondary battery charge.

[0034] According to the invention, an alkali metal secondary battery is further provided, containing or consisting of a) an anode, b) a cathode; and c) a solid electrolyte according to the invention.

[0035] The alkali metal secondary battery according to the invention has all the advantages that result from the solid electrolyte according to the invention.

[0036] The anode of an alkali metal secondary battery can contain or consist of lithium. Therefore, an alkali metal secondary battery could also be a lithium metal secondary battery.

[0037] Furthermore, the cathode of an alkali metal secondary battery can contain or consist of sulfur and electrically conductive carbon. Therefore, the alkali metal secondary battery can be an alkali metal-sulfur secondary battery (e.g., a lithium metal-sulfur secondary battery).

[0038] The following figure and examples are intended to explain the subject matter of the invention in more detail, without limiting it to the specific embodiments shown here.

[0039] Fig.Figure 1 schematically shows a structure of a solid electrolyte according to the invention. The solid electrolyte contains a plurality of core-shell particles 1. The core 2 of the core-shell particle 1 has a diameter of 5 µm and consists of a solid electrolyte material suitable for chemical reaction with metallic lithium (e.g., from Li 10 GeP2S 12 , Li6PS5Cl or Li 3-3x Sc x Sb). The shell 3 of the core-shell particle 1 has a thickness of 50 nm and consists of a 75Li2S-23P2S5-2P2O5 glass-ceramic, i.e., a glass-ceramic made of 75 mol% Li2S, 23 mol% P2S5, and 2 mol% P2O5. The shell 3 of said glass-ceramic protects the core 2 from a chemical reaction with metallic lithium in the anode of a secondary battery and also exhibits a high ionic conductivity for lithium ions (approximately in the range of 10). -4S / cm at 25 °C). If core 2 consists of Li6PS5Cl, it has an ionic conductivity of approximately 2 × 10 -3 S / cm. Since the thickness of the shell 3 is about 100 times less than the thickness of the core 2, the solid electrolyte has a relatively high ionic conductivity, very close to 2 × 10 -3 S / cm (at 25 °C). If the core 2 is made of Li 3-3x Sc x Sb, if present, exhibits an ionic conductivity of approximately 42·10 -3 S / cm. Since the thickness of the shell 3 is about 100 times less than the thickness of the core 2, the solid electrolyte also has a relatively high ionic conductivity, very close to 42 × 10 -3 S / cm (at 25 °C), where the electronically relatively good conductive Li 3-3x Sc x An additional advantage is that the electronic conductivity is reduced from the original approximately 4·10 -4 S / cm of the Li 3-3x Scx Sb nucleus 2 through the 50 nm thick shell 3 by about four orders of magnitude into the range of about 10 -8 S / cm can be reduced, which represents an acceptable range for applications in secondary batteries. Example 1 - Provision of particles of a solid electrolyte

[0040] The production of solid electrolytes is known to those skilled in the art. Furthermore, a large number of solid electrolytes suitable for chemical reaction with metallic lithium are commercially available. For example, the sulfide solid electrolyte Li6PS5Cl (CAS No.: 1015037-41-8) is available from Merck KGaA (Darmstadt, Germany).

[0041] If the solid electrolyte is present in a larger mean particle size than the desired mean particle size, the solid electrolyte particles can be reduced to a desired mean particle size D, for example, in a planetary ball mill, attritor ball mill, stirred ball mill, via jet milling and / or cryogenic milling. 50 The material should be ground. A dry, inert atmosphere (e.g., O2 and H2O < 1 ppm each) should be used, and the energy input should be controlled to avoid thermal damage to the solid electrolyte material. Example 2 - Provision of a glass containing or consisting of Li2S-P2S5-P2O5

[0042] To produce a glass containing or consisting of Li2S-P2S5-P2O5, glass formation processes known to those skilled in the art can be carried out.

[0043] For example, the following procedure can be used: 1. Providing Li2S as the first component; 2. Deploying P2S5 as a second component; 3. Providing P2O5 as a third component; 4. Optional provision of at least one additional component (e.g. Li2O, Li3N and / or LiY, where Y = Cl, Br or I); 5. Determine the stoichiometry for the glass to be produced (e.g. 75 mol% Li2S, 23 mol% P2S5 and 2 mol% P2O5); 6. Mixing the components into a mixture; 7. Melting the mixture (e.g. for a period of 30 seconds to 5 minutes, preferably 1 to 2 minutes) at a temperature above the glass transition temperature (e.g. 1 to 30 K, preferably 2 to 20 K, in particular 3 to 10 K, above the glass transition temperature; preferably at a temperature in the range of 190 to 300 °C) in a crucible until a homogeneous melt is obtained; 8. Quenching the molten metal; 9. Grinding the quenched glass melt into a glass powder, preferably such that the particles of the glass powder have a diameter in a desired range (e.g. a diameter in the range of 1 nm to 50 nm, wherein the diameter refers in particular to a diameter determined by electron microscopy); and 10. Drying the glass powder (e.g. at approx. 100 to 180 °C in a vacuum or a dry Ar / O2-deficient atmosphere). Example 3 - Provision of a glass ceramic containing or consisting of Li2S-P2S5-P2O5

[0044] To produce a glass ceramic containing or consisting of Li2S-P2S5-P2O5, methods for glass ceramic formation known to those skilled in the art can be carried out.

[0045] For example, the following procedure can be used: 1. Providing Li2S as the first component; 2. Deploying P2S5 as a second component; 3. Providing P2O5 as a third component; 4. Optional provision of at least one additional component (e.g. Li2O, Li3N and / or LiY, where Y = Cl, Br or I); 5. Determine the stoichiometry for the glass ceramic to be produced (e.g. 75 mol% Li2S, 23 mol% P2S5 and 2 mol% P2O5); 6. Mixing the components into a mixture; 7. Melting the mixture (e.g. for a period of 30 seconds to 5 minutes, preferably 1 to 2 minutes) at a temperature above the glass transition temperature (e.g. 1 to 30 K, preferably 2 to 20 K, in particular 3 to 10 K, above the glass transition temperature; preferably at a temperature in the range of 190 to 300 °C) in a crucible until a homogeneous glass melt is obtained; 8. Tempering the glass melt (e.g. for a period of 0.5 hours to 5 hours, particularly preferably 1 hour to 4 hours, particularly 2 hours to 3 hours) at a temperature above the crystallization temperature (e.g. 1 to 30 K, preferably 2 to 20 K, particularly 3 to 10 K, above the crystallization temperature, preferably at a temperature in the range of 240 to 300 °C) until a glass ceramic is formed; 9. Allow the glass ceramic to cool; 10. Grinding the cooled glass ceramic into a glass ceramic powder, preferably such that the particles of the glass ceramic powder have a diameter in a desired range (e.g. a diameter in the range of 1 nm to 50 nm, wherein the diameter refers in particular to a diameter determined by electron microscopy); and 11. Drying the glass ceramic powder (e.g. at approx. 150 to 200 °C in a vacuum or dry Ar / O2-deficient atmosphere). Example 4 - Provision of a solid electrolyte according to the invention

[0046] To produce the core-shell particles, methods known to those skilled in the art for the production of core-shell particles can be carried out.

[0047] For example, the following procedure can be used: 1. Preparation of a mixture of solid electrolyte particles (e.g., 95 to 99.5 wt.% based on the total weight of the mixture, mean diameter D) 50 preferably in the range of 1 to 10 µm) and glass particles and / or glass-ceramic particles (e.g. 0.5 to 5 wt.% in relation to the total weight of the mixture, diameter preferably in the range of 1 to 50 nm) in a dry and inert atmosphere (e.g. O2 and H2O each < 1 ppm); 2. Mixing the mixture to deposit the glass particles and / or glass-ceramic particles onto the surface of the solid electrolyte particles. This step can be carried out, for example, using a method selected from the group consisting of mechanofusion processes (e.g., Hosokawa mechanofusion), spray coating processes, granulation processes (e.g., in a fluidized bed granulator or drum granulator), and combinations thereof. A mechanofusion process (e.g., Hosokawa mechanofusion) is preferred because the coating can be very homogeneous and dense. 3. Annealing the mixture in a dry and inert atmosphere (e.g., O₂ and H₂O each < 1 ppm) to soften and melt the glass particles and / or glass-ceramic particles, wherein the annealing (e.g., for a period of 30 seconds to 5 minutes, preferably 1 to 2 minutes) is carried out at a temperature above the glass transition temperature (e.g., 1 to 30 K, preferably 2 to 20 K, particularly 3 to 10 K, above the glass transition temperature), but, in the case of (only) glass particles in the mixture, below the crystallization temperature (preferably at a temperature in the range of 190°C to 300°C). In this step, it can be advantageous to agitate the mixture (e.g., in a fluidized bed granulator or drum granulator), as this reduces the risk of the individual particles "sticking together" due to their soft, molten shell. If a mechanofusion procedure is used in step 2 (e.g.If the Hosokawa mechanofusion process has been carried out, annealing can create an even denser (i.e., pore-free and crack-free) glass layer or glass-ceramic layer on the solid electrolyte cores; and. 4. Allow the mixture to cool.

[0048] After the mixture has cooled, core-shell particles are present, the core of which consists of a solid electrolyte (e.g. Li6PS5Cl) and whose shell surrounds the core homogeneously, continuously and with few pores (ideally completely pore-free).

[0049] Scanning electron microscopy (SEM) and / or transmission electron microscopy (TEM), optionally combined with energy-dispersive X-ray spectroscopy (EDX), can be used to check whether the glass and / or glass-ceramic is present as a layer or shell on the solid electrolyte particles (as core) and also to evaluate the properties of the layer.

[0050] The core-shell particles can be mixed with a polymeric binder and processed, for example, into a freestanding film. Example 5 - Provision of an alkali metal secondary battery according to the invention

[0051] To produce an alkali metal secondary battery according to the invention, methods known to those skilled in the art for producing alkali metal secondary batteries can be used, wherein a solid electrolyte according to the invention is used instead of a solid electrolyte from the prior art.

[0052] For example, the following procedure can be used: 1. Provide a lithium metal foil (e.g., with a thickness in the range of 20 to 50 µm); 2. Applying the lithium metal foil to a metallic collector (e.g., a copper foil); 3. Production of a sulfur-carbon composite, for example by mixing sulfur with a conductive carbon (e.g., Ketjen black, acetylene grit, porous carbons), optionally carrying out a melt impregnation by heating above the melting point of sulfur and diffusing the molten sulfur into the porous carbon); 4. Application of the sulfur composite, optionally using a binder (e.g. PVDF, styrene-butadiene rubber and / or carboxymethylcellulose) to a metallic collector (e.g. an Al foil); 5. Arrangement of a solid electrolyte according to the invention between the lithium metal foil and the sulfur composite to produce a layered composite; and 6. Pressing the layered composite together (e.g. by cold pressing or hot pressing). QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited non-patent literature

[0000] Zhang et al., “Synergistic Li6PS5Cl@Li3OCl composite electrolyte for high-performance all-solid-state lithium batteries,” Green Energy & Environment, 10:793-803

[0003]

Claims

[1] Solid electrolyte containing core-shell particles, or consisting thereof, wherein the core of the core-shell particle contains or consists of a solid electrolyte material suitable for chemical reaction with metallic lithium, characterized by that the shell of the core-shell particles i) contains or consists of a glass containing or consisting of Li2S-P2S5-P2O5; and / or ii) contains or consists of a glass ceramic containing or consisting of Li2S-P2S5-P2O5. [2] Solid electrolyte according to the preceding claim, characterized bythat the solid electrolyte material suitable for chemical reaction with metallic lithium contains or consists of a solid electrolyte material of a type selected from the group consisting of argyrodite type, thio-LISICON type, LGPS type, chloride-doped thiophosphate, LLZO type, NASICON type, LLTO type, halide type, antiperovskite type and combinations thereof, wherein the solid electrolyte material is preferably selected from the group consisting of Li7Ge3PS 12 , Li 10 GeP2S 12 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li6PS5Cl, Li6PS5Br, Li3PS4, Li7La3Zr2O 12 , Li 1+x Al x Ti 2-x (PO4)3, Li 1+x Al x Ge 2-x (PO4)3, La2 / 3-x Li3xTiO3, Li3YCl6, Li3InCl6, Li 3-3x SC x Sb and combinations thereof. [3] Solid electrolyte according to any one of the preceding claims, characterized by, that the glass and / or glass-ceramic of the shell of the core-shell particles, i) contains 40 to 80 mol% Li2S, preferably 50 to 76 mol% Li2S, particularly preferably 60 to 70 wt% Li2S, with respect to the total molar mass of the shell; and / or ii) Contains 19 to 45 mol% P2S5, preferably 22 to 40 mol% P2S5, particularly preferably 26 to 35 mol% P2S5, with respect to the total molar mass of the shell; and / or iii) 1 to 15 mol% P2O5, particularly preferably 2 to 10 mol% P2O5, particularly preferably 4 to 5 mol% P2O5, with respect to the total molar mass of the shell; and / or iv) Li2O contains, preferably 1 to 15 mol% Li2O, particularly preferably 2 to 10 mol% Li2O, with respect to the total molar mass of the shell; and / or v) Li3N contains, preferably 1 to 5 mol% Li3N, particularly preferably 2 to 4 mol% Li3N, with respect to the total molar mass of the shell; and / or vi) LiY contains, preferably 5 to 20 mol% LiY, particularly preferably 8 to 15 mol%, with respect to the total molar mass of the shell, wherein Y = Cl, Br or I. [4] Solid electrolyte according to any one of the preceding claims, characterized by that the core of the core-shell particle has a mean diameter D 50 in the range of 1 to 20 µm, preferably 1.5 to 10 µm, particularly preferably 2 to 5 µm, wherein the mean diameter D 50 in particular on a mean diameter D measured by laser diffraction 50 refers to. [5] Solid electrolyte according to any one of the preceding claims, characterized by that the shell of the core-shell particles i) has a thickness in one direction along a radius of the core-shell particles in the range of 1 nm to 100 nm, preferably 2 nm to 50 nm, particularly preferably 5 nm to 30 nm, and in particular 10 nm to 20 nm, wherein the thickness refers in particular to a thickness measured by transmission electron microscopy; and / or ii) the glass and / or the glass-ceramic in a weight fraction in the range of 0.5 to 5 wt.%, preferably 1.0 to 4 wt.%, particularly preferably 1.5 to 3 wt.%, in particular 2 to 2.5 wt.%, with respect to the total weight of core and shell. [6] Solid electrolyte according to any one of the preceding claims, characterized by that the solid electrolyte contains a polymeric binder, wherein the polymeric binder is preferably i) contains or consists of a polymer selected from the group consisting of polyethylene oxide, polyethylene oxide copolymer, polyacrylate, polymethacrylate, polydopamine, PTFE, PVDF, polyvinylidene fluoride copolytrifluoroethylene, fluorinated polysiloxane and combinations thereof; and / or ii) contains a conducting salt, preferably LiTFSI; and / or ii) at least 0.1 wt.%, preferably at least 0.5 wt.%, in relation to the total weight of the solid electrolyte in which solid electrolyte is present; and / or iii) to a maximum of 5 wt.%, preferably a maximum of 4 wt.%, particularly preferably a maximum of 3 wt.%, most preferably a maximum of 2 wt.%, in particular a maximum of 1 wt.%, optionally a maximum of 0.5 wt.%, in relation to the total weight of the solid electrolyte in which the solid electrolyte is present; and / or iv) is present at least partially, preferably completely, in the form of fibrils. [7] Solid electrolyte according to any one of the preceding claims, characterized by that the core-shell particles of the solid electrolyte, preferably the entire solid electrolyte, a i) electronic conductivity in the range of ≤ 10 -9 S / cm, preferably ≤ 10 -10 S / cm , especially preferred ≤ 10 -11 S / cm, especially ≤ 10 -12 S / cm, exhibits; and / or ii) an ionic conductivity for lithium ions in the range of ≥ 10 -4 S / cm, preferably ≥ 10 -3 S / cm, especially preferred ≥ 5·10 3 S / cm, especially ≥ 10 -2 S / cm, exhibits. [8] Solid electrolyte according to any one of the preceding claims, characterized by that the core-shell particles of the solid electrolyte are contained in a layer which optionally includes a binder, wherein the layer preferably has a thickness in the range of i) has a minimum thickness of 1 µm; and / or ii) has a maximum thickness of 100 µm, preferably a maximum thickness of 80 µm, particularly preferably a maximum thickness of 60 µm, most preferably a maximum thickness of 40 µm, in particular a maximum thickness of 20 µm, optionally a maximum thickness of 10 µm. [9] Alkali metal secondary battery, containing or consisting of d) an anode, e) a cathode; and f) a solid electrolyte according to any one of claims 1 to 8. [10] Solid electrolyte according to any one of the preceding claims, characterized by that the anode contains or consists of lithium and / or the cathode contains or consists of sulfur and an electrically conductive carbon.

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