A composition comprising a sulfidic solid material containing alkali metals, P, S and halogen elements

Abstract

The present disclosure relates to a composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, the elements P and S, and at least one halogen, and further comprising cerium oxide (CeO2) in an amount ranging from 0.05 wt% to 10 wt% based on the weight of the solid sulfide material. The present disclosure also relates to a process for the preparation of the composition (C). Finally, the present disclosure relates to a solid electrolyte, a secondary battery, an electrode and a separator comprising the composition (C).

Description

[0001] This application claims priority to European Patent Application No. 23307246.1, filed on 18 December 2023, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0002] This disclosure relates to a composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, elements P and S, and at least one halogen, and further comprising cerium oxide (CeO2) in an amount ranging from 0.05 wt% to 10 wt% based on the weight of the solid sulfide material. This disclosure also relates to a method for preparing the composition (C). Finally, this disclosure relates to solid electrolytes, secondary batteries, electrodes, and separators comprising the composition (C). Background Technology

[0003] Lithium-ion batteries are widely used as power sources, especially for electrical appliances. In these secondary batteries, organic solvents are used as organic liquid electrolytes, and lithium ions migrate from one electrode to another depending on whether the battery is being charged or discharged.

[0004] Since the solvent used as the electrolyte is flammable, all-solid-state lithium-ion batteries that do not use organic solvents are very attractive. Such all-solid-state lithium-ion batteries are formed by curing the entire battery using a solid sulfide electrolyte, for example, containing Li, P, S, and halogens.

[0005] Solid sulfide electrolytes are highly hygroscopic materials and can hydrolyze in the presence of water from ambient air, producing gaseous H2S as the main byproduct. H2S is highly toxic and corrosive, thus posing a threat to personnel and equipment.

[0006] Strategies to reduce the risk of H2S release are crucial for ensuring the commercial success of a technology. Active strategies include, for example, modifying the material through doping, which leads to changes in the crystal structure, potentially accompanied by improvements in the chemical stability of the solid sulfide electrolyte. Passive strategies can be alternatives, where the material is not modified and, for example, H2O or H2S traps are used to prevent H2S release into the atmosphere.

[0007] Regardless of the strategy used, the impact on the performance of solid sulfide electrolytes (such as ionic conductivity) must be minimized.

[0008] In this invention, passive strategies are considered a feasible and cost-effective way to reduce H2S release into the atmosphere in the event of accidents, improper packaging, or mishandling, as well as during cycles. Several scientific teams have previously used such passive strategies.

[0009] For example, US 2013 / 0011746 A1 relates to providing solid sulfide electrolyte materials for all-solid-state lithium secondary batteries, which contain Fe, Zn, or Bi oxides (such as Fe₂O₃, ZnO, or Bi₂O₃) capable of preventing the external generation of hydrogen sulfide. It has been found that ZnO and Bi₂O₃ are the most efficient at reducing H₂S generation when solid sulfide electrolyte materials containing these oxides are exposed to air. Due to the limited electrochemical stability of Bi₂O₃, ZnO better maintains the high ionic conductivity of the solid sulfide electrolyte material. However, by introducing ZnO into the sulfide, the ionic conductivity is reduced to half or lower. The same results were published in the Journal of Materials Chemistry A, 2013, 1, 6320-6326.

[0010] JP 2020061260 A relates to providing a solid electrolyte for all-solid-state lithium-ion batteries, which contains Li₂S and P₂S₅ and does not generate H₂S while maintaining good ionic conductivity. For this purpose, the solid sulfide electrolyte of this invention contains PbO₂ or SnO₂, and comparative examples include solid sulfide electrolytes without oxides or containing ZrO₂ or TiO₂. This technical solution has the disadvantage of involving materials containing harmful metals (such as Pb or Sn). Furthermore, if those oxides are added to the solid sulfide electrolyte to moderately reduce the amount of H₂S generated, it will also lead to a significant reduction in ionic conductivity, which is reduced to 1 / 2 and at least 1 / 5.

[0011] The Journal of Non-Crystalline Solids, 364 (2013), 57-61, discloses that adding Li2O to Li2S-P2S5 glass reduces H2S gas production while maintaining the relatively high ionic conductivity of the glass sulfide electrolyte material. However, by introducing Li2O into the sulfide glass, the ionic conductivity is reduced to 1 / 3 or lower.

[0012] Finally, JP 2017120728 A2 relates to the use of Li2O to reduce H2S gas generation in silver sulfide germanium ore electrolyte materials having the formula Li6PS5Cl, while maintaining the ionic conductivity of said silver sulfide germanium ore electrolyte materials. However, the amount of Li2O added was too low (< 1.5 wt%) so that its effect on reducing H2S generation was not clearly observed. Summary of the Invention

[0013] The applicant recognizes that solid sulfide electrolytes containing Li, P, S and halogens have poor stability during storage, especially when exposed to ambient moisture.

[0014] The applicant recognizes that solid sulfide electrolytes containing Li, P, S and halogens may release H2S during storage, especially when exposed to ambient moisture, during accidents, improper packaging or handling, and during cycling.

[0015] Solid sulfide electrolyte powder containing Li, P, S and halogens that needs to remain stable when exposed to moisture during storage or transportation and does not release H2S.

[0016] Solid sulfide electrolyte powder containing Li, P, S and halogens is required to remain stable in the presence of a cycled battery and to not release H2S.

[0017] The applicant notes that existing solutions for preparing solid sulfide electrolytes containing Li, P, S and halogens (which remain stable and do not produce H2S release) by adding metal oxides require the use of harmful metals and / or are detrimental to the ionic conductivity of the solid sulfide electrolytes.

[0018] Solid sulfide electrolyte powder containing Li, P, S and halogens is required to remain stable when exposed to moisture during storage or transportation and to have high ionic conductivity and low activation energy.

[0019] There is a need for novel solid sulfide electrolytes containing metal oxides and incorporating Li, P, S, and halogens. These novel solid sulfide electrolytes would provide stability against increased air moisture and prevent the release of H2S, while maintaining high ionic conductivity and low activation energy.

[0020] A method is needed for preparing a novel solid sulfide electrolyte containing Li, P, S and halogens, comprising the metal oxides.

[0021] Therefore, the problem facing the applicant is to provide a solid sulfide electrolyte containing Li, P, S and halogens that can meet the above requirements.

[0022] The present invention relates to a composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, elements P and S, and at least one halogen, and further comprising cerium oxide (CeO2) in an amount ranging from 0.05 wt% to 10 wt%, preferably 0.2 wt% to 6 wt%, more preferably 0.4 wt% to 4 wt%, and even more preferably 0.5 wt% to 2 wt% based on the weight of the solid sulfide material.

[0023] The present invention also relates to a method for preparing composition (C).

[0024] The present invention also relates to a solid electrolyte comprising the composition (C) according to the present invention.

[0025] The present invention also relates to a secondary battery comprising a solid electrolyte according to the invention; more particularly, a lithium secondary battery.

[0026] The present invention also relates to an electrode comprising the composition (C) according to the present invention.

[0027] The present invention also relates to a diaphragm comprising the composition (C) according to the present invention. Detailed Implementation

[0028] The present invention relates to a composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, elements P and S, and at least one halogen, and further comprising cerium oxide (CeO2) in an amount ranging from 0.05% by weight to 10% by weight based on the solid sulfide material.

[0029] The inventors have unexpectedly discovered that this composition exhibits stability in response to increased air moisture, while maintaining high electrical conductivity and low activation energy.

[0030] The reaction between gaseous H2S and metal oxides is typically described as shown in Scheme 1 below:

[0031]

[0032] Unbound by any theory, this reaction is considered irreversible and responsible for efficient H2S capture.

[0033] The composition (C) typically contains cerium oxide (CeO2) in an amount ranging from 0.05% to 10% by weight, preferably from 0.2% to 6% by weight, more preferably from 0.4% to 4% by weight, and even more preferably from 0.5% to 2% by weight, based on the solid sulfide material.

[0034] Composition (C) typically contains at least one solid sulfide material containing at least one alkali metal selected from Li and Na, elements P and S, and at least one halogen.

[0035] In some preferred embodiments, the alkali metal is Li. Therefore, the at least one solid sulfide material comprises Li, P, and S, as well as at least one halogen.

[0036] In some embodiments, the solid sulfide material corresponds to formula (I):

[0037] Li 7-y PS 6-y X y (I)

[0038] Where X is selected from the list of the following: F, Cl, I, Br or a combination thereof; where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.6.

[0039] With X being Cl and y equal to 1, good results were obtained using Li6PS5Cl.

[0040] In some other embodiments, the solid sulfide material corresponds to formula (II):

[0041] Li 7-2x-y A x PS 6-y X y (II)

[0042] X can be selected from the following list: F, Cl, I, Br or a combination thereof;

[0043] A is an alkaline earth metal element selected from Be, Sr, Ca, Mg and Ba;

[0044] Where x is a number such as 0.01 ≤ x < 0.5;

[0045] Where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.6.

[0046] In some other embodiments, the solid sulfide material corresponds to formula (III):

[0047] Li 7-x’-y A' x’ PS 6-y X y (III)

[0048] X can be selected from the following list: F, Cl, I, Br or a combination thereof;

[0049] A' is selected from Na, K, Rb, Cs, Cu, and Ag;

[0050] Where x' is a number such as 0.01 ≤ x' < 0.5;

[0051] Where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.6.

[0052] The solid sulfide materials of formulas (I)-(III) can be crystalline or glassy materials.

[0053] Solid sulfide materials can be any commercially available material having formulas (I)-(III).

[0054] Solid sulfide materials having formulas (I)-(III) can be prepared using any method known to those skilled in the art.

[0055] For example, particles of solid sulfide materials having formulas (I)-(III) can be prepared by a method including the following steps.

[0056] i) The composition is obtained by optionally mixing the starting materials in one or more solvents;

[0057] ii) Apply mechanical treatment to the composition obtained in step i);

[0058] iii) Optionally, at least a portion of the one or more solvents is removed from the composition obtained in step ii) to obtain a solid precursor;

[0059] iv) Optionally, the solid precursor from step iii) is pressed into granules;

[0060] v) The precursor obtained in step iii), for example in granular form, is heated under an inert atmosphere to a temperature ranging from 300°C to 700°C for a period of 1 to 12 hours to form solid sulfide material particles; and

[0061] vi) Optionally, the solid sulfide material obtained in step v) can be processed to a desired particle size distribution.

[0062] The starting material of step i) is introduced in a relative amount suitable for obtaining the target stoichiometry of solid sulfide material.

[0063] For example, when preparing a solid sulfide material having formula (I), the starting material in step i) may include lithium sulfide (Li2S), phosphorus sulfide (P2S5), and a compound having formula LiX (where X represents at least one halogen element).

[0064] As an example, when preparing a solid sulfide material having formula (II), the starting material in step i) may include lithium sulfide (Li2S), phosphorus sulfide (P2S5), a compound having formula LiX, and at least one alkaline earth metal element compound (such as BeS, SrS, CaS, MgS, BaS, BeX2, SrX2, CaX2, MgX2, and BaX2) (where X represents at least one halogen element).

[0065] As an example, when preparing a solid sulfide material having formula (III), the starting material in step i) may include lithium sulfide (Li2S), phosphorus sulfide (P2S5), a compound having formula LiX, and at least one compound such as Na2S, K2S, Cs2S, Cu2S, Ag2S, NaX, KX, CsX, CuX, and AgX (where X represents at least one halogen element).

[0066] By way of example only, the solvent in step i) may be selected from aliphatic hydrocarbons (e.g., hexane, heptane, octane, or nonane, preferably heptane) and aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, xylene, or liquid cycloalkanes, preferably xylene). For example, the solvent may be selected from the group consisting of xylene, p-xylene, heptane, octane, and mixtures thereof.

[0067] Cerium oxide with the chemical formula CeO2 can be obtained, for example, by calcination of cerium oxalate, cerium carbonate, or cerium hydroxide. Alternatively, cerium oxide can be obtained by precipitation reaction of a Ce(NO3)3, 6H2O solution promoted by the addition of NaOH.

[0068] In addition, cerium oxide can be prepared as described in US 2010072417 A2.

[0069] Alternatively, commercially available cerium oxide can be used.

[0070] Typically, solid sulfide materials and cerium oxide exist in the composition (C) in particulate form.

[0071] Therefore, the composition (C) according to the invention is a powder composition comprising a solid sulfide material in particulate form and cerium oxide (CeO2).

[0072] Typically, solid sulfide materials exist in particulate form, and these particles have a median particle size (D50) that is greater than that of cerium oxide particles (D50).

[0073] Typically, solid sulfide materials exist in particulate form, with a median particle size (D50) ranging from about 0.5 to about 40 µm; sometimes from about 1 to about 20 µm; and usually from about 5 to about 15 µm.

[0074] Typically, cerium oxide particles exist in particulate form, and these particles have a median particle size (D50) in the range of about 1 to about 3,000 nm, sometimes in the range of about 5 to about 2,000 nm, usually in the range of about 10 to about 700 nm, and even more usually in the range of about 50 to about 500 nm, such as in the range of about 100 to about 400 nm.

[0075] Dn corresponds to the n% of particles with a diameter smaller than Dn. D50 (median) is defined as the size value corresponding to the cumulative distribution at 50%. The D50 value corresponds to the median particle size of the distribution.

[0076] These parameters are typically determined by the volumetric distribution of the diameter of the solid material particles in a solution, obtained using a laser diffractometer and a pre-defined standard procedure in the instrument's software. A laser diffractometer measures particle size by measuring the intensity of the diffracted light as a laser beam passes through a dispersed particulate sample. A laser diffractometer can be, for example, the Mastersizer 3000 manufactured by Malvern.

[0077] Particle size distribution (PSD) (e.g., D50, D10, and D90 values) can be measured by laser diffraction, for example, in p-xylene or isomeric xylene. The data can be processed using Fraunhofer's optical model.

[0078] In some other embodiments, the composition (C) according to the invention is an aggregated powder comprising a solid sulfide material in particulate form, cerium oxide, and a polymer binder (P).

[0079] Composition (C) is characterized by low H2S emissions under given conditions. In fact, when the composition is exposed to an atmosphere of humid air with a relative humidity of 35% for 60 minutes, the H2S release r is less than 90 mL / g of the composition, measured at 23°C. Therefore, r is determined by a simple test involving exposing the composition to a humid atmosphere and measuring the amount of H2S released during the first 60 minutes of contact between the composition and said atmosphere. Relative humidity is well known to those skilled in the art. It corresponds to the ratio of the partial pressure of water vapor in atmospheric air / water to the equilibrium vapor pressure of water at a given temperature. r can be less than 75 mL / g. r is typically greater than 1 mL / g.

[0080] Under the same experimental conditions, the emission rate of H2S, expressed as mL H2S / g / h, can also be determined. This rate is less than 90 mL H2S / g / h.

[0081] Composition (C) typically exhibits an ionic conductivity greater than 0.5 mS / cm, preferably greater than 1.0 mS / cm, and more preferably greater than 2.0 mS / cm, as measured by impedance spectroscopy at 23°C for pressed (500 MPa) pellets. The ionic conductivity is typically less than 12 mS / cm, and more particularly less than 10 mS / cm.

[0082] The ionic conductivity (σ) can be measured on pressed pellets. Typically, pressed pellets are manufactured using uniaxial pressure or isostatic pressure. When uniaxial pressure is applied to form pellets, a pressure higher than 100 MPa, preferably higher than 300 MPa, is applied for a duration of at least 30 seconds. Measurements are typically performed at uniaxial pressures between 2 MPa and 200 MPa.

[0083] The ionic conductivity value (σ) can be obtained at different temperatures. The activation energy value is determined using the slope of the σT versus 1 / T plot. Composition (C) typically exhibits a low activation energy value.

[0084] Therefore, the inventors have found that the composition (C) according to the invention is particularly suitable for use as a solid electrolyte in a secondary battery.

[0085] Another object of the present invention relates to a method for preparing a composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, elements P and S, and at least one halogen, and further comprising cerium oxide (CeO2) in an amount ranging from 0.05% by weight to 10% by weight based on the solid sulfide material.

[0086] Therefore, another object of the present invention is a method for preparing the composition (C) according to the invention, the method comprising mixing particles of a sulfide solid material with particles of cerium oxide (CeO2), as previously described.

[0087] The method for preparing the composition (C) according to the invention can be a dry method (i.e., in which mixing involves only solid particles) or a wet method (in which the particles are mixed in the presence of a liquid medium).

[0088] The dry process is typically carried out at temperatures ranging from -20°C to 60°C; preferably from -10°C to 50°C; and more preferably from 0°C to 40°C. Good results were obtained at room temperature.

[0089] Mixing can be carried out using any equipment well known to those skilled in the art that is suitable for mixing solid particles and powders composed of solid particles in the presence of a liquid medium.

[0090] For illustrative purposes only, the mixing of sulfide solid material particles with cerium oxide particles can be carried out in a plowshare mixer, a vertical belt mixer, a vertical conical screw mixer, a double conical mixer, a V-type mixer, or a horizontal belt mixer.

[0091] In some embodiments, mixing is performed as high-energy mixing. For example, high-energy mixing can be performed in a ball mill (e.g., a planetary ball mill).

[0092] Good results were obtained by manually mixing the powder using a mortar and pestle.

[0093] When the method used to prepare the composition (C) according to the invention is a wet process, it includes the following steps:

[0094] a) Mixing particles of at least one sulfide solid material as previously described with particles of cerium oxide (CeO2) or a cerium oxide precursor in the presence of a liquid medium to obtain a composition (C');

[0095] b) Remove the liquid medium from the composition (C') obtained in step a) to obtain composition (C).

[0096] Step a) can be performed using any equipment well known to those skilled in the art, such as those described above.

[0097] In some embodiments, in step a), particles of sulfide solid material and particles of cerium oxide (CeO2) are suspended in a liquid medium.

[0098] Therefore, the liquid medium consists of one or more solvents in which the sulfide solid material and cerium oxide (CeO2) are substantially insoluble or completely insoluble. "Substantially insoluble" means that less than 5 wt%, preferably less than 1 wt%, of the sulfide solid material and cerium oxide (CeO2) are dissolved.

[0099] Therefore, liquid media typically contain at least one solvent selected from aliphatic hydrocarbons (e.g., hexane, heptane, octane, or nonane, preferably heptane) and aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, xylene, or liquid cycloalkanes, preferably xylene). For example, a liquid medium may contain or consist of a solvent, which may be selected from the group consisting of xylene, p-xylene, heptane, octane, and mixtures thereof.

[0100] In some other embodiments, in step a), the particles of the sulfide solid material are suspended in the liquid medium, and the particles of cerium oxide (CeO2) are partially or completely dissolved in the liquid medium.

[0101] Therefore, the liquid medium consists of one or more solvents in which the sulfide solid material is substantially insoluble or completely insoluble, while cerium oxide (CeO2) is partially or completely dissolved. "Substantially insoluble" means that less than 5 wt%, preferably less than 1 wt%, of the sulfide solid material is dissolved. "Partially dissolved" means that at least 5 wt%, preferably at least 15 wt%, of cerium oxide is dissolved.

[0102] In some other embodiments, in step a), the particles of the sulfide solid material are suspended in a liquid medium, and the particles of the cerium oxide (CeO2) precursor are partially or completely dissolved in the liquid medium. In this embodiment, step b) typically further includes a step of forming cerium oxide (CeO2) from the precursor prior to finally obtaining composition (C).

[0103] In embodiments where cerium oxide (CeO2) or its precursor is partially or completely dissolved, the liquid medium typically comprises at least one solvent selected from fatty alcohols (e.g., methanol, ethanol, or propanol), and optionally one or more solvents selected from aliphatic hydrocarbons (e.g., hexane, heptane, octane, or nonane, preferably heptane) and aromatic hydrocarbons (e.g., benzene, toluene, ethylbenzene, xylene, or liquid cycloalkanes, preferably xylene). For example, the liquid medium comprises ethanol and optionally the following solvents, or is composed of ethanol and optionally the following solvents, which may be selected from the group consisting of xylene, p-xylene, heptane, octane, and mixtures thereof.

[0104] Therefore, the wet process used to prepare composition (C) (in which cerium oxide (CeO2) or the precursor of cerium oxide (CeO2) is partially or completely dissolved) is a highly efficient mixing process similar to impregnation or initial wetting impregnation, which are well known methods for dispersing nanoparticles (here, cerium oxide) on the surface of a carrier (here, a sulfide solid material).

[0105] The precursors of cerium oxide (CeO2) can be, for example, CeCl3 or Ce(NO3)3.

[0106] In the wet process, step a) is typically carried out at a temperature preferably between the melting temperature and the boiling temperature of the selected liquid medium.

[0107] In the wet process, step a) is typically carried out at a temperature ranging from -10°C to 60°C; preferably from 0°C to 50°C; and more preferably from 10°C to 40°C. Good results can be obtained at room temperature.

[0108] Step b) can be performed using any means well known to those skilled in the art to remove the liquid medium containing one or more solvents from the composition. Liquid removal can be carried out by known methods, such as decantation, filtration, centrifugation, drying, or combinations thereof.

[0109] The temperature in step b) can be selected to allow the removal of the liquid medium. When drying is selected as the method for removing the liquid, the temperature is preferably selected below the boiling point and based on the vapor partial pressure of the selected liquid medium.

[0110] In step b), removing the liquid medium means removing at least about 97%, 98%, 99%, or 100% of the total weight of the liquid medium used, or any range between these values.

[0111] The composition (C) of the present invention can be used to manufacture solid electrolytes.

[0112] The present invention also includes a solid electrolyte comprising the composition (C) described herein.

[0113] The solid electrolyte according to the invention comprises composition (C) and, optionally, at least one lithium-ion conductive material (LiCM) other than the solid sulfide material of composition (C), such as a lithium conductive oxide, like lithium-filled garnet Li7La3Zr2O. 12 (LLZO).

[0114] The solid electrolyte according to the invention may optionally contain a polymer (such as styrene-butadiene rubber), an organic or inorganic stabilizer (such as SiO2), or a dispersant.

[0115] The present invention also includes an electrochemical device comprising the solid electrolyte described herein.

[0116] Preferably, in electrochemical devices, especially rechargeable electrochemical devices, the solid electrolyte is a component of the solid structure of the electrochemical device selected from the group consisting of a cathode, an anode, and a diaphragm.

[0117] The present invention also relates to a solid-state battery, more preferably an alkali metal battery, and particularly a lithium battery, which includes the solid electrolyte described herein.

[0118] The present invention also relates to a solid-state secondary battery, more preferably an alkali metal battery, and particularly a lithium battery, comprising at least one (e.g., two or more) electrochemical devices of the present invention.

[0119] Typically, a lithium solid-state battery includes a positive electrode active material layer containing a positive electrode active material, a negative electrode active material layer containing a negative electrode active material, and a solid electrolyte layer formed between the positive electrode active material layer and the negative electrode active material layer. At least one of the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contains a solid electrolyte as defined above.

[0120] The present invention also relates to an electrode comprising:

[0121] - Metal substrate;

[0122] - At least one layer directly attached to the metal substrate, the at least one layer being made of a composition (C”) comprising:

[0123] (i) The composition (C) of the present invention;

[0124] (ii) At least one electroactive compound (EAC);

[0125] (iii) Optionally, at least one lithium-ion conductive material (LiCM) other than the solid sulfide material of composition (C);

[0126] (iv) Optionally at least one conductive material (ECM);

[0127] (v) Optionally, lithium salts (LIS) other than lithium-ion conductive materials (LiCM) and solid sulfide materials of composition (C);

[0128] (vi) Optionally, at least one polymer adhesive material (P).

[0129] Electroactive compounds (EACs) are compounds that can bind or insert lithium ions into their structure and release lithium ions during the charging and discharging phases of an electrochemical device. An EAC can be a compound capable of inserting and deintercalating lithium ions into its structure. For the positive electrode (cathode), an EAC can be a complex metal chalcogenide having the formula LiMeQ2, wherein:

[0130] - Me is at least one metal selected from the group consisting of Co, Ni, Fe, Mn, Cr, Al and V;

[0131] - Q is a chalcogenide element such as O or S.

[0132] More specifically, EAC can have the formula LiMeO2. Preferred examples of EAC include LiCoO2, LiNiO2, LiMnO2, and LiNi x Co 1-x O2 (0 < x < 1), LiNix Co y Mn z O2 (0 < x, y, z < 1 and x + y + z = 1), e.g., LiNi 1 / 3 Mn 1 / 3Co 1 / 3 O2, LiNi 0.6 Mn 0.2 Co 0.2 O2, LiNi 0.8 Mn 0.1 Co 0.1 O2, Li(Ni) x Co y Al z O2 (x+y+z=1) and spinel-structured LiMn2O4 and Li(Ni) 0.5 Mn 1.5 )O4.

[0133] EAC can also be of the form M1M2(JO4). f E 1-f Electroactive materials based on lithiated or partially lithiated transition metal oxygen anions, wherein:

[0134] - M1 is lithium, which can be replaced by another alkali metal portion that accounts for less than 20% of M1;

[0135] - M2 is a transition metal selected from Fe, Co, Mn, Ni or mixtures thereof with an oxidation state of +2, which may be replaced by one or more additional metal moieties with an oxidation state between +1 and +5 and comprising less than 35% (inclusive) of the metal M2;

[0136] - JO4 is any oxygen anion in which J is P, S, V, Si, Nb, Mo or a combination thereof;

[0137] - E is a fluoride anion, hydroxide anion, or chloride anion;

[0138] - f is the mole fraction of JO4 oxoanion, which is usually included between 0.75 and 1.

[0139] As defined above, M1M2(JO4) f E 1-f Electroactive materials are preferably phosphate-based. They can exhibit ordered or modified olivine structures.

[0140] For the positive electrode, EAC can also be sulfur or Li2S.

[0141] For the positive electrode, EAC can also be a conversion material, such as FeS2, FeF2, or FeF3.

[0142] For the negative electrode, the EAC can be selected from the group consisting of graphitic carbon that enables lithium intercalation. More details about this type of EAC can be found in Carbon 2000, 38, 1031-1041. This type of EAC typically exists in the form of powder, flakes, fibers, or spheres (e.g., mesophase carbon microspheres).

[0143] EAC can also be: lithium metal; lithium alloy compositions (e.g., those described in US 6,203,944 and WO 00 / 03444); lithium titanate, which is typically composed of the formula Li4Ti5O 12 These compounds are generally considered to be “zero-strain” intercalation materials, which absorb mobile ions (i.e., Li₂) + It exhibits low levels of physical expansion; lithium-silicon alloys, often referred to as lithium silicides with high Li / Si ratios, particularly those with the formula Li 4.4 Lithium silicide of Si; and lithium-germanium alloys, including those having the formula Li 4.4 The crystalline phase of Ge. EAC can also be based on composite materials of carbon-containing materials with silicon and / or silicon oxide, especially graphite carbon / silicon and graphite / silicon oxide, wherein the graphite carbon is composed of one or more types of carbon that enable lithium intercalation.

[0144] The lithium-ion conductive material (LiCM) other than the solid sulfide material of composition (C) can be a lithium conductive oxide, such as lithium-filled garnet Li7La3Zr2O. 12 (LLZO).

[0145] Conductive materials (ECMs) are typically selected from the group consisting of conductive carbon-containing materials and metal powders or fibers. Conductive carbon-containing materials can be, for example, selected from the group consisting of carbon black, carbon nanotubes, graphite, graphene, and graphite fibers, and combinations thereof. Examples of carbon black include Ketjen black and acetylene black. Metal powders or fibers include powders or fibers of nickel and aluminum.

[0146] Lithium salts (LIS) can be selected from the group consisting of: LiPF6, lithium bis(trifluoromethanesulfonyl)imide, lithium bis(fluorosulfonyl)imide, LiB(C2O4)2, LiAsF6, LiClO4, LiBF4, LiAlO4, LiNO3, LiCF3SO3, LiN(SO2CF3)2, LiN(SO2C2F5)2, LiC(SO2CF3)3, LiN(SO3CF3)2, LiC4F9SO3, LiCF3SO3, LiAlCl4, LiSbF6, LiF, LiBr, LiCl, LiOH, and lithium 2-trifluoromethyl-4,5-dicyanimidazolium.

[0147] The function of a polymeric adhesive (P) is to hold the components of a composition (C”) together. Polymer adhesives are generally inert. They are preferably also chemically stable and conducive to electron and ion transport. Polymer adhesives are well known in the art. Non-limiting examples of polymeric materials (P) include, in particular: (1) polymers based on VDF or TFE, especially in the form of copolymers, block copolymers, or graft copolymers; (2) hydrogenated or non-hydrogenated diene-based rubber polymers, especially in the form of block copolymers and graft polymers, such as polyisobutylene (PIB), styrene-butadiene rubber (SBR), (hydrogenated) acrylonitrile-butadiene rubber ((h)NBR), styrene-ethylene-butene-styrene (SEBS), etc.; (3) Polymers containing at least one alkyl methacrylate, especially in the form of copolymers, block copolymers and graft copolymers, such as polymethyl methacrylate (PMMA), polybutyl acrylate (BA), styrene-butyl acrylate (ST-BA), styrene-methyl acrylate (ST-MA), butyl acrylate-acrylonitrile (BA-CN), etc.; (4) Polysaccharide-based polymers, copolymers, block copolymers and graft copolymers, such as carboxymethyl cellulose (CMC), guar gum, etc.; (5) Acrylonitrile-based polymers, especially in the form of copolymers, block copolymers and graft polymers, such as poly(acrylonitrile) (PAN), acrylonitrile-methyl acrylate (PAN-MA), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylate (ASA), etc.; (6) Polyamide-imide (PAI) polymers, copolymers, block copolymers and graft polymers.

[0148] The polymeric material (P) can be selected from a list of (co)polymer compositions based on vinylidene fluoride (VDF). More specifically, the polymeric material (P) can be a copolymer comprising VDF and hexafluoropropylene (HFP) units or composed thereof.

[0149] The polymeric material (P) can be selected from a list of optional hydrogenated thermoplastic elastomers based on styrene. More specifically, the polymeric material (P) can be styrene-butadiene rubber (SBR) or styrene-ethylene-butene-styrene (SEBS).

[0150] The polymeric material (P) can be selected from a list of polymer compositions containing acrylonitrile units. More specifically, the polymeric material (P) can be a copolymer of acrylonitrile, butadiene, and / or butyl acrylate.

[0151] The proportion of composition (C) in composition (C”) of the present invention can be between 0.1 wt% and 80 wt% based on the total weight of composition (C”). In particular, this proportion can be between 1.0 wt% and 60 wt%, and more particularly between 5 wt% and 30 wt%. The thickness of the electrode is not particularly limited and should be adapted to the energy and power required in the application. For example, the thickness of the electrode can be between 0.01 mm and 1,000 mm.

[0152] A separator is a membrane that allows ions to pass through, placed between the anode and cathode of a battery. Its function is to allow lithium ions to pass through while blocking electrons and ensuring physical isolation between the electrodes.

[0153] The present invention also relates to a diaphragm comprising:

[0154] - The composition (C) of the present invention;

[0155] - Optionally, at least one polymer adhesive material (P);

[0156] - Optionally at least one metal salt, especially a lithium salt (LIS) other than the solid sulfide material of composition (C);

[0157] - Optionally, at least one plasticizer.

[0158] Electrodes and membranes can be prepared using methods well-known to those skilled in the art. This typically involves mixing the components in a suitable solvent and then removing the solvent. For example, electrodes can be prepared by methods including the following steps:

[0159] - A slurry containing the components of composition (C”) and at least one solvent is applied to a metal substrate;

[0160] - Remove solvent.

[0161] Commonly known techniques to technicians include coating and calendering, dry and wet extrusion, 3D printing, and sintering followed by impregnation of porous foam. Common techniques for fabricating electrodes and diaphragms are described in the Journal of Power Sources, 2018, 382, ​​160-175. Other techniques may be used, such as extrusion, paste extrusion, (electro)spraying, and kneading followed by calendering.

[0162] Electrochemical devices, especially batteries (such as solid-state batteries described herein), can be used to manufacture or operate automobiles, computers, personal digital assistants, mobile phones, watches, camcorders, digital cameras, thermometers, calculators, laptop BIOS, communication equipment or remote car locks, as well as stationary applications such as energy storage devices for power plants.

[0163] Electrochemical devices, particularly batteries (such as solid-state batteries described herein), can be used in motor vehicles, electric bicycles, robots, aircraft (e.g., unmanned aerial vehicles including drones), ships, or stationary energy storage devices. Preferred are mobile devices, such as vehicles, bicycles, aircraft, or watercraft such as boats or ships. Other examples of mobile devices are portable mobile devices, such as computers, especially laptops, telephones, or power tools, such as power tools from the construction industry, especially drill bits, battery-powered screwdrivers, or battery-powered nailers.

[0164] If any disclosure of any patent, patent application, or publication incorporated herein by reference conflicts with this specification to the extent that it may obscure the terminology, this specification shall prevail. Example

[0165] Material

[0166] Li2S was obtained from Lorad (99.9% purity, 100% screened to less than 75 µm).

[0167] P2S5 (purity > 99%) and LiCl (purity > 99%) were obtained from Sigma Aldrich.

[0168] ZnO nanoparticles (< 100 nm particle size) were obtained from Sigma-Aldrich.

[0169] CeO2 nanoparticles (< 25 nm particle size) were obtained from Sigma-Aldrich.

[0170] XRD analysis

[0171] XRD patterns of the powder were acquired using a Cu X-ray tube (Cu Kα wavelength 1.5406 Å) on an XRD goniometer (Malvern Panalytical Aeris) with Bragg-Brentano geometry. The tube was set to operate at 40 kV / 15 mA, 600 W. The setup was used with a fixed slit of 0.02 radians and a Soller slit. Filtering devices on the master side, such as nickel filters, monochromators, or Bragg-Brentano HD optics from Panalytical, could also be used. The sample holder was mounted on the rotator; the rotation speed was typically 60 rpm during acquisition. The acquisition step size was 0.0108° per step. The angular range was typically 10° to 90° or greater in 2θ. The total acquisition time was typically 30 min or longer. Measurements were performed in a drying chamber at a dew point between -43°C and -47°C.

[0172] Particle size distribution measurement

[0173] Particle size distribution (PSD) of the powder was evaluated using laser diffraction measurements. For this purpose, the powder was stirred in isomerized xylene (Carlo Erba). The solvent was dried with molecular sieves to ensure the absence of trace amounts of water. Prior to measurement, a suspension of 0.3 wt.% sulfide was prepared and stirred at 3000 rpm for 30 min in an Ultraturrax (IKA) with a rotor and stator. Aliquots of the suspension were then taken and introduced into the analytical apparatus (Malvern Mastersizer 3000). The data were processed using a Fraunhofer optical model.

[0174] Example 1: Preparation of Li6PS5Cl

[0175] Step a): 22.7 g of LiCl (Sigma-Aldrich, >99% purity), 59.5 g of P2S5 (Sigma-Aldrich, >99% purity), and 61.5 g of Li2S (Lord, 100%, 200 mesh) were weighed sequentially and added to a glass container. The powders were homogenized by gentle manual mixing. They were then added to a 500 mL zirconia bowl (Across) containing 480 g of ZrO2 balls (5 mm, Across). 106.3 g of p-xylene (Sigma-Aldrich, >99% purity, dry) was then added and used to rinse the powder from the glass container directly inside the zirconia bowl. The bowl was quickly sealed to prevent any p-xylene evaporation. Wet ball milling was performed using an Across PQ-N2 planetary ball mill. After milling at 580 rpm for 65 h, a pale yellow / beige paste was obtained.

[0176] The paste was transferred to a dry alumina crucible and dried under dynamic vacuum at 130°C to remove p-xylene. The p-xylene was condensed with ice water and drying continued until the volume of condensed xylene was equal to the volume introduced in the wet ball milling step. After drying for 5 hours, the grinding balls were separated from the light beige powder by sieving at 4 mm.

[0177] Step b): The dried mixture was loaded into a quartz reactor under dry air (dew point < -15°C). The reactor was then inserted into a rotary oven and the product was crystallized at 490°C for 12 hours (heating ramp 1.5°C / min) at a speed of 9 rpm under a flow of N2 (30 L / h). It was then cooled to 50°C under the same N2 flow and speed. The final product was ground to obtain a powder.

[0178] The crystalline phase of sulfosilver germanite was confirmed by XRD.

[0179] The particle size distribution is such that 5 µm ≤ D50 ≤ 10 µm and D90 < 30 µm.

[0180] Example 2: Preparation of Li6PS5Cl / CeO2 composition

[0181] The CeO2 powder was heat-treated under vacuum at 80°C for 5 hours, until a constant weight was measured. The resulting dried CeO2 and the Li6PS5Cl powder from Example 1 were then manually mixed by hand with a mortar and pestle for 5 minutes until a homogeneous mixture was produced. The composition of the mixture is given in Table 1.

[0182] XRD confirmed the presence of two compounds: CeO2 additive and silver-germanium sulfide phase.

[0183] Comparative Example 1: Preparation of Li6PS5Cl / ZnO Composition

[0184] The ZnO powder was heat-treated under vacuum at 80°C for 5 hours, until a constant weight was measured. The resulting dried ZnO and the Li6PS5Cl powder from Example 1 were then manually mixed by hand with a mortar and pestle for 5 minutes until a homogeneous mixture was produced. The composition of the mixture is given in Table 1.

[0185] XRD confirmed the presence of two compounds: a ZnO additive and a sulfide-silver-germanium mineral phase.

[0186] H2S emission measurement

[0187] Sample preparation was performed in a dry Ar glove box (moisture level < 5 ppm, O2 level < 5 ppm). Samples (100 mg powder) were placed in circular containers with a surface area of ​​4.02 cm. 2The sample was placed in an open circular holder. The holder was then placed on a zirconia flask, where it was isolated from the atmosphere. The zirconia flask was transferred from a dry argon glove box to an indoor air-operated glove box for H2S quantification. The relative humidity was set at 30%–35% (equivalent to a dew point of 6.2°C) at room temperature (25°C). Humidity was measured using a dew point probe (EA2-TX-100) from Mitchell Instruments. Humidity within the glove box was controlled via the inlet of pre-dried compressed air. The atmosphere within the glove box was homogenized by two fans. Once the atmosphere was stable, the zirconia flask was opened, exposing the sample to the controlled humid atmosphere. H2S quantification was performed using a Sensorcon sensor (Industrial Pro – H2S Pro). The experiment lasted 60 minutes, at which point the zirconia flask was closed again. The H2S release rate (r) is expressed as ml H2S / g composition (ml / g).

[0188] Conductivity measurement

[0189] Conductivity was obtained from granules produced using a uniaxial press operating at 500 MPa. Measurements were performed under a 40 MPa load, using two carbon paper foils as current collectors in a pressure cell unit (BATTE-CELL-0067EQ-PSC-15-P) from MTI. Impedance spectra were acquired at room temperature (23°C) using a Biologic VMP3 apparatus, with temperature control ensured via a Binder climate chamber. A two-hour duration was set to allow temperature equilibration between measurements.

[0190] Impedance spectra were acquired in PEIS mode with an amplitude of 10 mV and a frequency range of 1 MHz to 1 kHz (25 points per decade and the average of 50 measurements per frequency point).

[0191] The conductivity σ of the reference material Li6PS5Cl at 23°C was normalized to 100, therefore the σ loss (%) of Example 1 at 23°C is 0%. The σ loss (%) of Comparative Example 1 at 23°C is -5% relative to the conductivity σ of the reference material Li6PS5Cl at 23°C.

[0192] Table 1:

[0193]

[0194] The results presented in Table 1 show that the presence of CeO2 in the sulfide Li6PS5Cl reduces H2S production more effectively than ZnO, while maintaining the higher ionic conductivity of the sulfide. Therefore, cerium oxide is suitable for achieving a good balance between H2S release control and the ionic conductivity of sulfides (e.g., Li6PS5Cl).

Claims

1. A composition (C) comprising at least one solid sulfide material containing at least one alkali metal selected from Li and Na, element P and S, and at least one halogen, and comprising cerium oxide (CeO2) in an amount ranging from 0.05% to 10% by weight based on the solid sulfide material.

2. The composition (C) according to claim 1, wherein, The alkali metal is Li.

3. The composition (C) according to claim 2, wherein, This solid sulfide material corresponds to formula (I): Li 7-y P.S. 6-y X y (I) Where X is selected from the list of the following: F, Cl, I, Br or a combination thereof; where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.

6.

4. The composition (C) according to claim 2, wherein, This sulfide solid material corresponds to formula (II): The 7-2x-y A x PS 6-y X y (II) X can be selected from the following list: F, Cl, I, Br or a combination thereof; A is an alkaline earth metal element selected from Be, Sr, Ca, Mg and Ba; Where x is a number such as 0.01 ≤ x < 0.5; Where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.

6.

5. The composition (C) according to claim 2, wherein, This sulfide solid material corresponds to formula (III): Li 7-x’-y A’ x’ PS 6-y X y (III) X can be selected from the following list: F, Cl, I, Br or a combination thereof; A' is selected from Na, K, Rb, Cs, Cu, and Ag; Where x' is a number such as 0.01 ≤ x' < 0.5; Where y is a number such as 0.5 ≤ y < 2; preferably a number such as 1.0 ≤ y ≤ 1.8; more preferably a number such as 1.0 ≤ y ≤ 1.

6.

6. The composition (C) according to any one of the preceding claims, wherein, The sulfide solid material exists in particulate form, and these particles have a median particle size obtained from the volume distribution that is higher than that of cerium oxide particles, as measured by laser diffraction in p-xylene.

7. The composition (C) according to any one of the preceding claims, wherein, The sulfide solid material exists in particulate form, with a median particle size of about 0.5 to about 40 µm obtained from the volume distribution, as measured by laser diffraction in p-xylene.

8. A method for preparing the composition (C) according to any one of claims 1 to 7, the method comprising mixing particles of a sulfide solid material with particles of cerium oxide (CeO2).

9. A method for preparing the composition (C) according to any one of claims 1 to 7, the method comprising the following steps: a) Mixing particles of at least one sulfide solid material with particles of cerium oxide (CeO2) or cerium oxide (CeO2) precursor in the presence of a liquid medium to obtain a composition (C'); b) Remove the liquid medium from the composition (C') obtained in step a) to obtain the composition (C).

10. The method according to claim 8 or claim 9, wherein, This mixing is carried out as a high-energy mixing process.

11. A solid electrolyte comprising the composition (C) according to any one of claims 1 to 7.

12. An electrochemical device comprising the solid electrolyte according to claim 11.

13. A solid-state secondary battery comprising the composition (C) according to any one of claims 1 to 7.

14. An electrode comprising: - Metal substrate; - At least one layer directly attached to the metal substrate, the at least one layer being made of a composition (C”) comprising: (i) The composition (C) according to claims 1 to 7; (ii) At least one electroactive compound (EAC); (iii) Optionally, at least one lithium-ion conductive material (LiCM) other than the solid sulfide material of composition (C); (iv) Optionally at least one conductive material (ECM); (v) Optionally, a lithium salt (LIS) other than the lithium-ion conductive material (LiCM) and the solid sulfide material of composition (C); (vi) Optionally, at least one polymer adhesive material (P).

15. A diaphragm comprising: - The composition (C) according to claims 1 to 7; - Optionally, at least one polymer adhesive material (P); - Optionally at least one metal salt, especially a lithium salt (LIS) other than the solid sulfide material of composition (C); - Optionally, at least one plasticizer.

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