Inorganic additives for capturing transition metal ions in sodium-ion batteries

Abstract

The present invention relates to a sodium-ion battery comprising an inorganic transition metal cation trap, such as hydroxyapatite. The present invention also relates to a positive electrode, a negative electrode, an electrolyte, and a separator comprising the inorganic transition metal cation trap.

Description

[Technical field]

[0001] This application claims priority to European Patent Application Publication No. 21315123.6, filed in Europe on July 7, 2021, the entire contents of which are incorporated herein by reference for all purposes.

[0002] The present invention relates to a sodium-ion battery comprising an inorganic transition metal cation trap, such as hydroxyapatite. The present invention also relates to a positive electrode, a negative electrode, an electrolyte, and a separator comprising the inorganic transition metal cation trap. [Background technology]

[0003] The demand for lithium-ion batteries has increased in recent years due to their application in a wide variety of electronic devices, such as mobile phones and electric vehicles. Indeed, lithium-based compounds are relatively expensive and natural lithium sources are not readily available, being unevenly distributed on the planet and localized in a few countries. Therefore, a replacement for this element is required. For this purpose, sodium-ion batteries have been developed, since sodium is very abundant and homogeneously distributed, advantageously non-toxic, and more economically advantageous.

[0004] Sodium-ion batteries generally operate by reversibly passing sodium ions between a negative electrode (anode) and a positive electrode (cathode). The negative and positive electrodes are generally located on either side of a porous separator that is impregnated with an electrolyte composition suitable for conducting sodium ions. Each electrode is associated with a current collector. The current collectors are connected to an external circuit that allows electrical current to flow between the electrodes to balance the associated movement of sodium ions. Summary of the Invention [Problem to be solved by the invention]

[0005] Dissolution of transition metal cations from the positive electrode in the electrolyte composition is a problem encountered by a wide variety of high voltage electrode materials in alkali ion battery technology, especially sodium ion battery technology. This phenomenon is detrimental due to the migration of cations at the anode side and their interference with the SEI structure. The main focus is the need for contingency measures, such as electrolyte modification to reduce the solubility of selected cations, or surface modification of the active material or the use of ion-selective membranes as separators.

[0006] The International Publication No. 2021 / 073467A1 brochure describes a cathode active material that is a low-value inactive transition metal, Li + The company has disclosed a sodium-ion battery that is doped with Li. During charging and discharging, the active ingredient in the electrolyte is Li + It interacts with ions to form a stable cathode electrolyte interfacial (CEI) film and inhibits the dissolution of other transition metal ions in the positive electrode active material.

[0007] US 2019 / 296305 A1 discloses a cation exchanger suitable for metal adsorption in non-aqueous electrolyte lithium batteries.

[0008] In sodium-ion batteries, different transition metal cations are expected to dissolve, depending on the nature of the cathode material. As just one example, vanadium cations (V 2+ , V 3+ , V 4+ Or V 5+ Dissolution of .ALPHA. is commonly observed during cycling of sodium fluorophosphate (NVPF) / hard carbon cells and reduces battery performance by depositing on the negative electrode.

[0009] It is necessary to prevent the dissolution of transition metal cations from the positive electrode of sodium-ion batteries. It is also necessary to prevent the migration of such transition metal cations from the positive electrode to the negative electrode. Finally, it is necessary to prevent the deposition of such transition metal cations on the negative electrode, which is detrimental to the solid electrolyte interphase interface (SEI) structure.

[0010] All these needs and others are addressed by: - a positive electrode; a negative electrode; a separator; an electrolyte composition; - an inorganic transition metal cation trap; This is accomplished by providing a sodium ion battery comprising:

[0011] definition Throughout this specification, unless the context requires otherwise, the terms "comprise" or "include" or variations such as "comprises," "comprising," "includes," "including" will be understood to imply the inclusion of a stated element or method step or group of elements or method steps, but not the exclusion of any other element or method step or group of elements or method steps. According to a preferred embodiment, the terms "comprise" and "comprises" and variations thereof mean "consisting only of".

[0012] As used herein, the singular forms "a", "an" and "the" include plural embodiments unless the context clearly indicates otherwise. The term "and / or" includes the meaning "and", "or" and also all other possible combinations of the elements associated with this term.

[0013] The term "~" should be understood to be inclusive.

[0014] Ratios, concentrations, amounts, and other numerical data may be presented in a range format herein. It should be understood that such range formats are used merely for convenience and brevity, and should be interpreted flexibly to include not only the numerical values ​​explicitly recited as the limits of the range, but also to include all the individual numerical values ​​or subranges contained within the range, as if each numerical value and subrange were explicitly recited. For example, a temperature range of about 120°C to about 150°C should be interpreted to include not only the explicitly recited limits of about 120°C to about 150°C, but also subranges such as 125°C to 145°C, 130°C to 150°C, etc., and individual amounts such as decimal points within the stated range, for example, 122.2°C, 140.6°C, and 141.3°C.

[0015] The term "electrolyte" refers in particular to ions, e.g. Na + An electrolyte is a material that allows the movement of ions, e.g. Na, through it, but does not conduct electrons. + They are useful for conducting current while electrically insulating the cathode and anode of a battery.

[0016] As used herein, the terms "cathode" and "anode" refer to the electrodes of a battery. During a charge cycle in a Na secondary battery, Na ions move away from the cathode and through the electrolyte to the anode. During a charge cycle, electrons move away from the cathode and through an external circuit to the anode. During a discharge cycle in a Na secondary battery, Na ions move through the electrolyte and from the anode to the cathode. During a discharge cycle, electrons move away from the anode and through an external circuit to the cathode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The present invention relates to - a positive electrode; a negative electrode; a separator; an electrolyte composition; - an inorganic transition metal cation trap; A sodium ion battery comprising: The inorganic transition metal cation trap reduces or prevents the migration of the transition metal cation to the negative electrode and its deposition at or on the negative electrode.

[0018] In a second aspect, the invention relates to a separator comprising a positive electrode, a negative electrode, an electrolyte, and the inorganic transition metal cation trap.

[0019] Further details regarding the present invention are set forth below, including the claims.

[0020] Inorganic transition metal cation traps As discussed above, the inorganic transition metal cation trap reduces or prevents the migration of the transition metal cation to the negative electrode and its deposition at or on the negative electrode.

[0021] The inorganic transition metal cation trap is generally selected from calcium phosphates. In some embodiments, the inorganic transition metal cation trap is selected from calcium phosphates such as tricalcium phosphate Ca3(PO4)2, octacalcium phosphate Ca8H2(PO4)6, dicalcium diphosphate Ca2P2O7, tricalcium phosphate Ca5(PO 10 )2, tetracalcium phosphate Ca4(PO4)2O, apatite Ca 10 (PO4)6(OH,F,Cl,Br)2, hydroxyapatite (HAP) and mixtures thereof.

[0022] Without being bound by any theory, calcium phosphates are believed to be effective traps for various transition metal species in the form of metal cations or in the form of metal cation-containing compounds. Two or more metal trapping mechanisms can be envisaged, including ion exchange involving the replacement of either Ca(I) or Ca(II) ions in the calcium phosphate framework, surface complexation, and dissolution-precipitation of a newly formed stable phosphate-containing phase.

[0023] In some embodiments, the inorganic transition metal cation trap is selected from hydroxyapatite (HAP). HAP has the general formula Ca with a molar Ca / P ratio of 1.67 (stoichiometric ratio). 10 (PO4)6OH2, but other metal cations are partially Ca 2+ It has a very flexible structure in which other anionic species can partially replace the phosphate and / or hydroxyl anions. As a result of these possible substitutions, the Ca / P ratio can change, which typically ranges from 1.50 to 2.08 depending on the preparation method. For example, carbonate groups can be inserted into the hydroxyapatite structure by replacing phosphate and / or hydroxyl groups to form carbonated hydroxyapatite. Thus, when replacing phosphate groups, carbonate groups contribute to HAP with a Ca / P ratio of greater than 1.67.

[0024] In some embodiments, the inorganic transition metal cation trap is selected from hydroxyapatites having a Ca / P ratio in the range of 1.50 to 2.00.

[0025] In some preferred embodiments, the inorganic transition metal cation trap is selected from hydroxyapatites having a Ca / P ratio in the range of 1.50 to 1.80.

[0026] In some more preferred embodiments, the inorganic transition metal cation trap is selected from hydroxyapatites having a Ca / P ratio in the range of 1.50 to 1.67.

[0027] In some even more preferred embodiments, the inorganic transition metal cation trap is hydroxyapatite having a molar Ca / P ratio of 1.60.

[0028] Naturally occurring HAP of various qualities is recovered after calcination and processing of bones such as fish bones, cattle bones (which contain large amounts of HAP). The main impurities are carbon and calcium carbonate, and such naturally occurring HAP is called bone charcoal. The Ca / P ratio of bone charcoal is generally less than 1.67. Different grades of bone char exist, and some undergo post-processing after calcination to reduce the amount of impurities.

[0029] Synthetic HAP can be synthesized by several methods, generally classified as dry, wet and high temperature.

[0030] Dry methods include solid phase synthesis and mechanochemical synthesis.

[0031] Solid-state reactions refer to the decomposition reaction of mixed solid reactants by heating, producing new solids and gases. Solid-state methods for preparing HAP generally involve chemical precursors containing calcium and phosphate that are ground and calcined. HAP synthesis can be carried out by reaction at high temperatures (around 1000°C), for example, between CaO and P2O5, CaHPO4 and CaO, Ca3(PO4)2 and Ca(OH)2, CaHPO4 and CaCO3, or CaCO3 and NH4H2PO4.

[0032] Mechanochemical synthesis is the induction of chemical reactions by compression, shear or friction through grinding and milling of reactants. HAP synthesis can be carried out by mechanochemical methods including, for example, CaO and P2O5, Ca3(PO4)2 and Ca(OH)2, Ca2P2O7 and CaCO3 or CaHPO4.2H2O, urea and CaCO3.

[0033] Wet-chemical production can be carried out by precipitation, for example by reacting calcium hydroxide and orthophosphoric acid at a pH above 9 by addition of acid to a dilute solution / suspension of the hydroxide. Hydroxyapatite is also recovered by precipitation during the reaction of calcium nitrate or calcium chloride with diammonium hydrogen phosphate and ammonium hydroxide as a pH adjuster. Treatment at a pH below 9 can lead to the production of calcium-deficient hydroxyapatite, i.e. with a Ca / P ratio below the stoichiometric ratio of 1.67. The recovered precipitated powder is generally calcined at 400°C to 600°C or higher to obtain stoichiometric hydroxyapatite. The morphological properties (shape and size), stoichiometry, specific surface area and crystallinity of the synthesized HAP by precipitation are greatly influenced by synthesis parameters such as temperature, time, reagent addition rate, calcination, pH, as well as the use of various reagents and their purity.

[0034] Another wet chemical manufacturing method is called the hydrothermal method. The hydrothermal method for synthesizing HAP uses high temperature and pressure to stimulate a reaction in an aqueous medium containing calcium and phosphate precursors. The hydrothermal method can be carried out, for example, using CaCO3, Ca(OH)2 or Ca(NO3)2.4H2O and (NH4)2(HPO4) at high temperature and pressure. Generally, the amount of calcium source, phosphate source and / or alkali source is set to control the Ca / P ratio of the product.

[0035] HAP can also be prepared by high temperature methods, including combustion spray pyrolysis techniques.

[0036] The combustion process uses a rapid exothermic and self-sustaining redox reaction between an oxidizer in the aqueous phase and an organic fuel. By way of example only, calcium nitrate or acetate and diammonium hydrogen phosphate can be used as the calcium and phosphate sources, respectively, and citric acid, succinic acid and urea can be used as fuels. The combustion process can produce highly crystalline HAP, typically with other phase impurities.

[0037] Spray pyrolysis consists of spraying a precursor solution into the flame of the hot zone of an electric furnace. The precursors are, for example, Ca3(PO4)2, Ca(NO3)2.4H2O and (NH4)2HPO4; Ca(C2H3O2)2 (calcium acetate) and (NH4)2HPO4; Ca(NO3)2, (NH4)2HPO4 and HNO3; Ca(OH)2 and H3PO4 or Ca(C2H3O2)2 and (CH3)3PO4. HAP phases can be produced by spray pyrolysis, generally with other calcium phosphate phases.

[0038] HAP may be crystalline, amorphous or partially crystalline depending on its manufacturing method. If HAP is crystalline, the crystals may have different shapes, such as rods or platelets. The morphology of the crystals may impart different properties to the HAP.

[0039] The HAP suitable for the present invention may be crystalline, amorphous or partially crystalline. Good results have been obtained with crystalline HAP. In general, the HAP suitable for the present invention is 40 ml. 2 / g~200m 2 / g, preferably 40m 2 / g~180m 2 Generally, HAP suitable for the present invention has a D50 size measured by laser diffraction in the range of 5 μm to 100 μm, preferably in the range of 5 to 60 μm. 2 Good results were obtained with crystalline HAP with a specific surface area of ​​1.0 μm / g and a D50 size of 45 μm.

[0040] Additionally, examples of the synthesis of hydroxyapatite suitable for the present invention can be found in WO15173437.

[0041] positive electrode A sodium-ion battery according to the present invention comprises a positive electrode or cathode comprising an electrochemically active cathode material, which determines the cell voltage and capacity, and therefore the energy density, of the sodium-ion battery, a sodium ion conducting material, at least one electronic conducting material, and optionally a binder.

[0042] The electrochemically active cathode materials are generally selected from Na-based layered transition metal oxides, Prussian Blue analogues and polyanion-type materials.

[0043] In some embodiments, the electrochemically active cathode materials are Na-based layered transition metal oxides classified as O3, P2, and P3 types depending on the stacking order of the oxygen layers. The P2 type structures generally respond to the general formula NaxMO2, where M represents a transition metal ion such as Co, Mn, and x is 2 / 3.

[0044] In some embodiments, the electrochemically active cathode material is Na 0.81 Fe[Fe(CN)6] 0.79 □ 0.21 , NaFe2(CN)6, Na1 .63 Fe 1.89 (CN)6, Na 1.72 MnFe(CN)6, Na 1.76 Ni 0.12 Mn 0.88 [Fe(CN)6] 0.98 , Na2Ni x Co 1-x A is an alkali metal ion, P is an N-coordinated transition metal ion, R is a C-coordinated transition metal ion, and □ has an [R(CN)6] vacancy, such as Fe(CN)6 (0≦x≦1, e.g., Na2CoFe(CN)6). x P[R(CN)6] 1-y □ y It is a Prussian blue analogue (PBA) of mH2O.

[0045] In some other embodiments, the electrochemically active cathode material comprises a series of tetrahedral anionic units (XO4) n - and their derivatives (X m O 3m+1 ) n- having the general formula Na x M y (XO4) n(wherein X=S, P, Si, As, Mo, and W, and M is a transition metal). 0.7 Phosphates such as FePO4 or NaMnPO4; x Sodium superionic conductors with NASICON-type structure of M2(XO4)3 (where 1≦x≦4, M=V, Fe, Ni, Mn, Ti, Cr, Zr, etc.; X=P, S, Si, Se, Mo, etc.), single transition metal types such as Na3V2(PO4)3(NVP), Na3Cr2(PO4)3, Na3Fe2(PO4)3; binary transition metal types such as Na2VTi(PO4)3, Na3FeV(PO4)3, Na4MnV(PO4)3, Na3MnZr(PO4)3, Na3MnTi(PO4)3, Na4Fe3(PO4)2(P2O7)(NFPP); pyrophosphates Na2FeP2O7, Na2MnP2O7, Na2CoP2O7, Na 4-x Fe 2+x / 2 (P2O7)2(2 / 3≦x≦7 / 8), e.g. Na 3.12 Fe 2.44 (P2O7)2 or Na 3.32 Fe 2.34 (P2O7)2, Na2(VO)P2O7, Na7V3(P2O7)4; fluorophosphates NaVPO4F, Na2CoPO4F, Na2FePO4F, Na2MnPO4F, Na3(VO 1-x PO4)2F 1+2x (0≦x≦1), such as Na3(VOPO4)2F or Na3V2(PO4)2F3(NVPF); fluorosulfates such as NaMSO4F (M=Fe, Co, Ni); mixed phosphates / pyrophosphates of the general formula Na4M3(PO4)2(P2O7), where M represents a transition metal, such as Na4Mn3(PO4)2(P2O7), Na4Co3(PO4)2(P2O7), Na4Ni3(PO4)2(P2O7), Na4Fe3(PO4)2(P2O7)(NFPP), Na7V4(P2O7)4(PO4); Na2Fe2(SO4)3, Na 2+2x Fe 2-x (SO4)3, Na 2+2x Co 2-x (SO4)3, Na 2+2x Mn2-x (SO4)3 (0≦x≦1); and silicates of the general formula Na2MSiO4 (M=Mn, Fe, Co, and Ni).

[0046] In some preferred embodiments, the electrochemically active cathode material is preferably NaVPO4F, Na2CoPO4F, Na2FePO4F, Na2MnPO4F, Na3(VO 1-x PO4)2F 1+2x (0≦x≦1), for example, Na3(VOPO4)2F or Na3V2(PO4)2F3(NVPF).

[0047] Good results have been obtained when the electrochemically active cathode material is Na3V2(PO4)2F3 (NVPF). In the NVPF compound with the molecular formula Na3V2(PO4)2F3, vanadium is present in the +III oxidation state. NVPF can be partially oxidized. In this case, the product is also characterized by the presence of vanadium in the +IV oxidation state and by the partial replacement of fluorine atoms by oxygen atoms. Partially oxidized NVPF has the formula Na3V2(PO4)2F 3-x O x (x is an integer from 0 to 2). These electrochemically active cathode materials can be doped with heteroelements (Fe, Ti, Co, Ni, Mn, Zr, etc.).

[0048] The positive electrode also comprises at least one electronically conductive material which may be selected from carbon fibers, carbon black, carbon nanotubes, graphene and their analogues. An example of a conductive material is Super P carbon, for example H30253, sold by Alfa Aesar. The positive electrode optionally comprises a binder which may advantageously be polymeric. The binder is advantageously selected from polytetrafluoroethylene, polyvinylidene fluoride or copolymers of vinylidene fluoride with at least one comonomer, such as hexafluoropropylene, polymers derived from carboxymethylcellulose, polysaccharides and latexes, in particular of the styrene / butadiene rubber type. The binder is preferably a copolymer of vinylidene fluoride with at least one comonomer, such as hexafluoropropylene. The binder may be, for example, the Solef® 5130 grade sold by Solvay.

[0049] The positive electrode composition can include 70.0% to 97.0% by weight of an electrochemically active cathode material, 1.5% to 15.0% by weight of an electronically conductive material, and 1.5% to 15.0% by weight of a binder.

[0050] negative electrode A sodium-ion battery according to the present invention comprises a negative electrode or anode comprising a suitable electrochemically active anode material, optionally an electronically conductive material, and optionally a binder.

[0051] Generally, the electrochemically active anode material is selected from carbon-based materials, conversion / alloying compounds, and alloying compounds.

[0052] In some other embodiments, the electrochemically active anode material is a carbon-based material selected from expanded graphite, soft carbon, which is a graphitic carbon that can be obtained from liquid or gas phase pyrolysis, or hard carbon, which is a non-graphitic carbon formed by solid phase pyrolysis of cellulose, charcoal, coal, sugars, or carbon nanomaterials, such as carbon nanotubes, graphene, or carbon nanofibers, and metal-organic framework (MOF) based carbon materials.

[0053] In some other embodiments, the electrochemically active anode material is a conversion / alloying material that converts metal oxides or sulfides into some new compound by chemical transformation. Suitable metal oxides are Fe3O4, SnO2, SnO, CuO, Co3O4, MoO3, MnO2, TiO2, NiO, MnO. Suitable metal sulfides are MoS2, ZnS, SnS2, FeS, CuS, Sb2S3, Co3S4, NiS, MoS, WS2, and suitable metal selenides are Sb3Se3, MoSe2, FeSe2, ZnSe, NiSe. Suitable metal phosphides are Se4P4, Sn4P3, CoP, FeP, MoP, CuP2.

[0054] In some other embodiments, the electrochemically active anode material is an alloying material, which is an element capable of forming an alloy with sodium. Suitable alloying materials are generally selected from Groups 14 and 15 elements, such as Si, Ge, Sn, Pb, P, Sb, Bi, and mixtures thereof. The alloying material may be mixed with an inert element, such as Co, Ni, Zn, Mo, Cu, Ti, Te, or F.

[0055] In some other embodiments, the electrochemically active anode material is an organic material such as a conjugated carboxylate organic compound, a Schiff base polymer, a polyamide, a polyquinone, or a conjugated polymer.

[0056] Good results have been obtained when the electrochemically active anode material is hard carbon.

[0057] Good results have been obtained when the electrochemically active cathode material is Na3V2(PO4)2F3 (NVPF) and the electrochemically active anode material is hard carbon.

[0058] The conductive material may be selected from carbon fibers, carbon black, carbon nanotubes, graphene and their analogues. An example of a conductive material is Super P carbon, for example H30253, sold by Alfa Aesar. The binder may advantageously be a polymer. The binder may advantageously be selected from polytetrafluoroethylene, polyvinylidene fluoride or copolymers of vinylidene fluoride with at least one comonomer, such as hexafluoropropylene, polymers derived from carboxymethylcellulose (CMC), polysaccharides and latexes, especially of the styrene / butadiene rubber (SBR) type. The binder is preferably a copolymer of vinylidene fluoride with at least one comonomer, such as hexafluoropropylene. The binder may be, for example, the Solef® 5130 grade sold by Solvay.

[0059] The negative electrode composition can include 70.0% to 98.0% by weight of an electrochemically active anode material, 0.0% to 15.0% by weight of an electronically conductive material, and 1% to 15.0% by weight of a binder.

[0060] Separator Separators useful for sodium-ion batteries generally consist of highly porous polymeric membranes including polypropylene, polyethylene, PVDF, metal oxide (SiO2, Al2O3) coated polypropylene or polyethylene, modified cellulose acetate or non-woven mats. Glass fiber non-woven mats and barium titanate based polymer ceramic membranes can also be used.

[0061] Good results obtained with a fiberglass nonwoven separator (Whatman® GF6).

[0062] Good results were obtained when the electrochemically active cathode material was Na3V2(PO4)2F3 (NVPF) and the electrochemically active anode material was hard carbon and a non-woven glass fiber separator (Whatman® GF6).

[0063] electrolyte composition The electrolyte composition is the contact medium between the cathode and anode that facilitates ion transport through the porous separator. The electrolyte composition contains sufficient ions for charge transfer reactions while providing electrical insulation. The electrolyte composition can be a liquid, gel, or solid.

[0064] In some embodiments, the electrolyte composition is liquid and includes a salt dissolved in an organic solvent. By way of example only, suitable salts are NaBF4, sodium trifluoromethanesulfonate (NaTF), sodium bis(trifluoromethanesulfonyl)imide (NaTFSI), sodium bis(fluorosulfonyl)imide (NaFSI), sodium 4,5-dicyano-2-(trifluoromethyl)imidazole (NaTDI), NaPF6, NaClO4, or mixtures thereof. Good results have been obtained with an electrolyte composition including NaPF6.

[0065] Further by way of example, suitable organic solvents are non-fluorinated cyclic carbonates such as ethylene carbonate, propylene carbonate, vinylene carbonate or vinylethylene carbonate, fluorinated cyclic carbonates such as fluoroethylene carbonate, non-fluorinated acyclic carbonates such as methyl ethyl carbonate, diethyl carbonate or dimethyl carbonate, and mixtures thereof. While not exhaustive, the electrolyte composition may include several other solvents such as diglyme, triglyme, fluorinated carbonates, fluorinated ethers, hydrofluorinated ethers or fluorinated esters.

[0066] Good results have been obtained with an electrolyte composition containing a mixture of ethylene carbonate and dimethyl carbonate.

[0067] Good results were obtained when the electrochemically active cathode material was Na3V2(PO4)2F3 (NVPF), the electrochemically active anode material was hard carbon, a non-woven glass fiber separator (Whatman® GF6), and the electrolyte composition was a mixture of NaPF6, ethylene carbonate, and dimethyl carbonate.

[0068] Incorporation of inorganic transition metal cation traps The inorganic transition metal cation trap according to the present invention can be incorporated into a sodium ion battery in the cathode, anode, separator, electrolyte composition, or any combination thereof.

[0069] In some embodiments, the inorganic transition metal cation trap is incorporated into the cathode by any means known to one skilled in the art. For example, the transition metal cation trap can be incorporated by timely mixing with the electrochemically active cathode material before adding the electronic conductive material and optionally the binder. As a further example, hydroxyapatite can be timely mixed with the electrochemically active cathode material before adding the electronic conductive material and optionally the binder. Hydroxyapatite can also be incorporated by mixing with a process solvent such as NMP before adding the electrochemically active cathode material in a planetary mixer.

[0070] In some embodiments, the inorganic transition metal cation trap is incorporated into the anode by any means known to those skilled in the art. For example, the inorganic transition metal cation trap can be incorporated by timely mixing with the electrochemically active anode material before adding the electronic conductive material and optionally the binder. As a further example, the hydroxyapatite can be timely mixed with the electrochemically active anode material before adding the electronic conductive material and optionally the binder. The hydroxyapatite can also be incorporated by mixing with a process solvent such as NMP before adding the electrochemically active cathode material in a planetary mixer.

[0071] In some other embodiments, the inorganic transition metal cation trap is incorporated into the separator by any means known to those skilled in the art, such as by coating the separator with an aqueous suspension of the inorganic transition metal cation trap and then drying. As a further example, hydroxyapatite can be incorporated into the separator by coating it with hydroxyapatite. This coating can be done using methods used to coat alumina and known to those skilled in the art. Hydroxyapatite can be coated alone, with a polymer, or with a polymer and additional inorganic materials such as alumina.

[0072] In some other embodiments, inorganic transition metal cation traps are incorporated into sodium ion batteries by adding a suspension of the transition metal cation trap into the electrolyte composition. For example, hydroxyapatite can be added to the electrolyte composition by mixing the powder with a solvent and then adding a sodium salt, or by mixing the powder with the formulated electrolyte.

[0073] In yet some other embodiments, inorganic transition metal cation traps are incorporated into sodium ion batteries in the cathode and separator.

[0074] In yet some other embodiments, inorganic transition metal cation traps are incorporated into sodium ion batteries in the cathode, anode and separator.

[0075] In some other embodiments, inorganic transition metal cation traps are incorporated into sodium ion batteries in the cathode, the anode, suspension in the electrolyte composition, and in the separator.

[0076] The amount of inorganic transition metal cation trap incorporated into a sodium ion battery typically represents 0.01% to 10% by weight of the electrochemically active cathode material.

[0077] Typically, the amount of HAP incorporated into a sodium ion battery corresponds to 0.01% to 20% by weight of the electrochemically active cathode material (eg, NVPF), preferably 0.1% to 5% by weight.

[0078] Transition metal cations According to the above description of the electrochemically active cathode material, the transition metal cations that are susceptible to dissolution from the electrochemically active cathode material in the electrolyte composition are generally Mn 4+ , Mn 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Cr 2+ , Cr 3+ , Co 2+ , Co 3+ , Ni 2+ , Ni 3+ , Mo 6+ , Ti 4+ , Zr 4+ , V 2+ , V 3+ , V 4+ , V 5+ and combinations thereof.

[0079] Preferably, the transition metal cation susceptible to dissolution from the electrochemically active cathode material in the electrolyte composition is Mn 4+ , Mn 3+ , Mn 2+ , Fe 2+ , Fe 3+ , Cr 2+ , Cr 3+ , Co 2+ , Co 3+ , Ni 2+ , Ni 3+ , V 2+ , V 3+ , V 4+ , V 5+ and combinations thereof.

[0080] More preferably, the transition metal cation susceptible to dissolution from the electrochemically active cathode material in the electrolyte composition is Fe. 2+ , Fe3+ , Co 2+ , Co 3+ , Ni 2+ , Ni 3+ , V 2+ , V 3+ , V 4+ , V 5+ and combinations thereof.

[0081] Even more preferably, the transition metal cation susceptible to dissolution from the electrochemically active cathode material in the electrolyte composition is V 2+ , V 3+ , V 4+ , V 5+ and combinations thereof.

[0082] Another object of the present invention is to disclose a positive electrode comprising the aforementioned inorganic transition metal cation trap. The positive electrode of the present invention can have all the features of the aforementioned positive electrodes.

[0083] It is yet another object of the present invention to disclose an anode comprising the aforementioned inorganic transition metal cation trap. The anode of the present invention can have all the features of the aforementioned anodes.

[0084] Another object of the present invention is to disclose an electrolyte composition comprising the aforementioned inorganic transition metal cation trap. The electrolyte composition of the present invention can have all the features of the aforementioned electrolyte compositions.

[0085] Finally, another object of the present invention is to disclose a separator comprising the inorganic transition metal cation trap described above. The separator of the present invention can have all the features of the separator described above.

[0086] To the extent that the disclosures of any patents, patent applications, and publications incorporated herein by reference conflict with the statements of this application to the extent that any term may be unclear, the statements of this application shall control. EXAMPLES

[0087] material Na3V2(PO4)2F3 (NVPF) was synthesized by Solvay according to Example 1 of WO2020025638A1.

[0088] The PVDF was obtained from Solvay Specialty Polymers and was grade Solef® 5130.

[0089] NaPF6 was obtained from Sigma Aldrich (purity >99%).

[0090] Ethylene carbonate (EC) and dimethyl carbonate (DMC) were purchased from Sigma Aldrich (purity >99%).

[0091] Hydroxyapatite was provided by Solvay Soda Ash & Derivatives and was of the grade Capterall® (D50: 45 μm; specific surface area 166 m 2 / g;Ca / P=1.6). As mentioned above, an example of the synthesis of hydroxyapatite suitable for the present invention can be found in WO15173437.

[0092] The porous properties of hydroxyapatite were determined after heat treatment under vacuum at 110 °C overnight (approximately 16 h). The BET specific surface area was determined by gas adsorption on a Micromeritics ASAP2020 machine. Prior to the analysis, samples (0.7-1 g) are pretreated under vacuum at 110 °C until a stable vacuum of 4-5 μbar is achieved. Measurements were performed using nitrogen as the adsorbent gas at 77 °K by the volumetric method according to the ISO 9277:2010 standard (Determination of the specific surface area of ​​solids by gas adsorption - BET method). The BET specific surface area was calculated over a relative pressure (P / P0) range varying from approximately 0.05 to 0.20.

[0093] Hydroxyapatite particle size measurements were performed on particles suspended in water using a Beckman Coulter LS230 laser diffraction particle size analyzer (750 nm laser) using particle size distribution calculations based on Fraunhofer diffraction theory (particles above 10 μm) and Mie scattering theory (particles below 10 μm), assuming the particles to be spherical. The mean diameter D50 is the diameter such that 50% by weight of the particles have a diameter less than that value.

[0094] electrode: The positive electrode was made of NVPF (Na3V2(PO4)2F3), carbon black, and PVDF in a weight ratio of 94:3:3, respectively, at 12 mg / cm. 2 The load was 1000. An aluminum current collector (thickness 20 μm) was used as the cathode.

[0095] The hard carbon (HC) electrode was prepared by mixing hard carbon, carbon black, and PVDF in a weight ratio of 94:3:3, respectively, at 6 mg / cm. 2 The anode was also equipped with an aluminum current collector (thickness 20 μm). Electrodes were punched out with diameters of 14 mm and 16 mm, respectively, and dried in a Buchi oven at 120 °C under vacuum for 12 h before use in a glove box (H2O<10 ppm, O2<5 ppm).

[0096] Preparation of electrolyte: A 1 mol / L solution of NaPF6 in EC:DMC (1:1 by weight) was prepared in a glove box by introducing 0.84 g of NaPF6 (white powder) into a 15 mL Nalgene vial, followed by 5 mL (5.95 g) of EC:DMC (1:1 by weight). The solution was manually stirred until the salt was completely dissolved.

[0097] Coin Cell Implementation: Eight CR2032inox coin cells were prepared in a glove box (HO<10 ppm, O<5 ppm) using the following components: 1 stainless steel spacer (thickness 0.5mm), One NVPF electrode (diameter 14 mm), 1 glass fiber separator (diameter 16 mm, thickness 250 μm), 1 HC electrode (diameter 16mm), 1 stainless steel spacer (thickness 1mm), 1 spring (thickness 1.4mm).

[0098] The coin cells were filled with 130 μL of 1 mol / L NaPF6 in EC:DMC (1:1 by weight) electrolyte, and excess electrolyte was removed before sealing.

[0099] The NVPF electrode was assembled into a complete cell configuration facing a hard carbon (HC) negative electrode in a 2032 (20 mm diameter x 3.2 mm thick) button cell construction. The button cell consisted of the NVPF positive electrode, the HC negative electrode, 100 μl of electrolyte, a 1 mm thick stainless steel current spacer, a 1.4 mm thick ring-shaped spring, a 250 μm thick glass fiber separator, and the rigid casing of the cell (two hollow pieces interlocked with a seal). These elements were kept under pressure by the spring inside the rigid casing and were then crimped to ensure the system was leak-proof.

[0100] Cycle Conditions: After 12 hours at OCV, the cell was run on a Biologic MPG 2 potentiostat at room temperature at a C / 10 rate of 2V to 4.25V (1C is 128mA / g NVPF The cells were cycled five times at 100 V (C-rate = 4.25 V) and then charged at the same C-rate to 4.25 V. The OCVs of the charged cells were all above 4.10 V after the last charge.

[0101] Cell dissociation: The charged coin cell was opened in a glove box using a Hohsen disassembly tool and the NVPF electrode was retrieved.

[0102] Dissolution of vanadium from NVPF electrodes: Eight charged NVPF electrodes were retrieved and immersed in 20 mL of 1 mol / L NaPF6 in EC:DMC (1:1 by weight) electrolyte (3.365 g NaPF6 in 20 mL (23.59 g) of solvent in a 30 mL Nalgene vial). The 30 mL sealed Nalgene vial was sealed with parafilm and placed in an oven outside the glove box at 55 °C for 7 days. After this aging step, no mass change was detected and the electrolyte turned green in color.

[0103] Preparation of HAP dispersion: After calendar aging, the vials were opened in a glove box and the aged electrolyte was divided into eight Nalgene vials (2.5 mL each). Two were kept as references and different amounts of hydroxyapatite (Solvay Capterall® provided by Solvay Soda Ash & Derivatives) were added to the others according to Table 1. The vials were then resealed with parafilm.

[0104] [Table 1]

[0105] The different dispersions were taken out of the glove box and magnetically stirred at room temperature for 24 hours.

[0106] How to insert: After precipitation of hydroxyapatite, the supernatant was extracted in a glove box. Vanadium was then loaded by ICP-OES (Inductively Coupled Plasma Optical Emission Spectroscopy) on an Analytic Jena PQ 9000 Elite. Samples were mineralized by microwave (common reaction method) and 8 mL of HNO3 (67%) was added to approximately 200 mg of supernatant. Samples were then diluted (by mass) with approximately 30 mL of ultrapure water and diluted again by half (by volume) for vanadium loading.

[0107] External calibration was performed with 0.05 / 0.1 / 0.2 / 0.3 mg / L solutions using the spectral lines from 290.881 to 292.464 nm.

[0108] Vanadium concentrations were reported by mass. Two test samples were performed for each reference and the analysis of these two test samples was reproducible. The uncertainty was estimated at 10%.

[0109] The results reported in Table 1 indicate that the amount of vanadium species remaining in solution in the electrolyte composition after precipitation of hydroxyapatite is dependent on the amount of hydroxyapatite that was present in the vial. Thus, it appears that hydroxyapatite acts as a vanadium cation trap when present in contact with an electrolyte composition in which the cations are dissolved.

Claims

1. a positive electrode, a negative electrode, a separator, an electrolyte composition, an inorganic transition metal cation trap, and a sodium ion battery comprising the same.

2. The sodium ion battery according to claim 1, wherein the inorganic transition metal cation trap reduces or prevents the movement of the transition metal cation to the negative electrode and its deposition at or on the negative electrode.

3. wherein the inorganic transition metal cation trap is tricalcium phosphate Ca ３ (PO ４ ) ２ , octacalcium phosphate Ca ８ H ２ (PO ４ ) ６ , dicalcium diphosphate Ca ２ P ２ O ７ , tricalcium phosphate Ca ５ (P ３ O １０ ) ２ , tetracalcium phosphate Ca ４ (PO ４ ) ２ O, apatite Ca １０ (PO ４ ) ６ (OH, F, Cl, Br) ２ , the sodium ion battery according to claim 1 or 2, which is selected from calcium phosphates such as hydroxyapatite (HAP) and mixtures thereof.

4. The sodium ion battery according to claim 3, wherein the inorganic transition metal cation trap is selected from hydroxyapatite having a Ca / P molar ratio in the range of 1.50 to 2.

00.

5. The positive electrode contains Na ３ V ２ (PO ４ ) ２ F ３ (NVPF), and the sodium ion battery according to claim 1 or 2.

6. The sodium ion battery according to claim 1 or 2, wherein the negative electrode contains hard carbon.

7. The electrolyte composition contains NaPF ６ The sodium ion battery according to claim 1 or 2, which contains ６ .

8. The sodium ion battery according to claim 1 or 2, wherein the inorganic transition metal cation trap is incorporated into the cathode.

9. The sodium ion battery according to claim 1 or 2, wherein the inorganic transition metal cation trap is incorporated into the anode.

10. The sodium ion battery according to claim 1 or 2, wherein the inorganic transition metal cation trap is incorporated into the electrolyte composition.

11. The sodium ion battery according to claim 1 or 2, wherein the inorganic transition metal cation trap is incorporated into the separator.

12. The transition metal cation is V ２＋ , V ３＋ , V ４＋ and V ５＋ The sodium ion battery according to claim 1 or 2, comprising cations from V such as

13. A positive electrode comprising an inorganic transition metal cation trap.

14. A negative electrode comprising an inorganic transition metal cation trap.

15. An electrolyte composition comprising an inorganic transition metal cation trap.

16. A separator comprising an inorganic transition metal cation trap.