Active material for lithium-ion electrochemical element

Abstract

A negative electrode for a lithium-ion electrochemical element, the electrode comprising: - a current collector, - an active material composition deposited on at least one of the faces of the current collector and comprising an active material which is a compound of formula M15 - xM'xM''1 - yM'''yO40-aXb in which: M represents one or more elements chosen from Nb, Ta and V, M' represents one or more elements chosen from Ti, Zr, Mo, Cr, As and Sb, M'' represents one or more elements chosen from Mo and W, M''' represents one or more elements chosen from Cr, V and Te, X represents a halogen, 0≤x≤7.5 ; 0≤y<1 ; 0≤a≤5 ; 0≤b≤1, the compound satisfying the relation (15-x)*5 + nx + (1-y)*6 + my =(40-a)*2 + b; n and m respectively denote the average oxidation states of M' and M'''. Abbreviated figure: Figure 1

Description

Title of the invention: Active material for lithium-ion electrochemical element technical field

[0001] The technical field of the invention is that of active materials for lithium-ion electrochemical elements, in particular active materials for a negative electrode of a lithium-ion electrochemical element. Background

[0002] Lithium-ion electrochemical elements are known in the prior art. They are commonly used in many fields such as automotive, telecommunications, electronic devices, and aerospace. Their operating principle is based on the reversible exchange of lithium ions between a positive electrode (cathode), most often a lithium oxide of a transition metal or a lithium phosphate of a transition metal, and a negative electrode (anode), for example, made of graphite. The negative and positive electrodes are separated by a separator. The assembly formed by the negative electrode, the positive electrode, and the separator constitutes an electrochemical beam. This beam is, for example, impregnated with a liquid organic electrolyte, often composed of a mixture of alkyl carbonates in which a lithium salt, for example lithium hexafluorophosphate (LiPF6), is dissolved.

[0003] A graphite-based negative electrode has a potential close to 0 V with respect to the Lr7Li couple. Its specific capacitance is approximately 350 mAh / g. Figure 1 shows the variation of the potential of a graphite-based electrode with respect to the Lr7Li couple during a charge / discharge cycle. However, the fact that the potential of the graphite electrode is close to 0 V leads to a risk of the formation of metallic lithium on the negative electrode when the electrochemical element approaches the end of the charge or when the charge is too rapid. The agglomeration of metallic lithium leads to the formation of dendrites that can eventually pierce the separator and cause an internal short circuit in the electrochemical element. The risk of an internal short circuit has led to the search for other, safer negative active materials.

[0004] Active materials with a potential further from the potential of the Li+ / Li couple than graphite have been discovered. Examples include titanium-based lithium oxides, such as Li4Ti5O2i2. This compound has an average potential close to 1.5 V vs. Lr7Li. Figure 1 shows the variation of the potential of a Li4Ti5O2i2-based electrode with respect to the Li+ / Li couple during a charge / discharge cycle. Electro-elements Chemicals including a negative electrode based on Li4Ti50i2 can be charged under high current with zero risk of dendrite formation. The disadvantage associated with the use of Li4Ti50i2, however, is its low specific capacitance, which is only about 170 mAh / g, half that of graphite, as shown in [Fig. 1].

[0005] Active materials exhibiting a potential of approximately 1.5 V with respect to the Li+ / Li couple and a specific capacitance greater than that of Li4Ti5Oi2 have been discovered. Examples include lithium oxides of titanium and niobium, such as the compound with the formula TiNb2O7, described, for example, in patent FR-B-3102890.

[0006] We are looking for new active materials having a potential sufficiently far from the potential of the Lr7Li couple, i.e. close to 1.5 V vs. Lr7Li, and a specific capacitance greater than that of Li4Ti50i2. Summary

[0007] To this end, the invention proposes an electrode comprising: - a current collector, - an active material composition deposited on at least one of the faces of the current collector and comprising an active material which is a compound of formula Mi5_xM'xM”i_yM”'y04o aXb in which: M represents one or more elements chosen from Nb, Ta and V, M' represents one or more elements chosen from Ti, Zr, Mo, Cr, As and Sb, M' ' represents one or more elements chosen from Mo and W, M'” represents one or more elements chosen from Cr, V and Te, X represents a halogen, 0 <x<7,5 ; 0 <y<l; 0 <a<5; 0 <b<l, the compound satisfying the relation (15-x)*5 + nx + (ly)*6 + my =(40-a)*2 + b; n and m respectively indicate the average oxidation states of M' and M'”.

[0008] The invention is based on the discovery that compounds of formula Mi5.xM'xM”iy M”'y04o aXb can be used as the active material for a negative electrode of a lithium-ion electrochemical element. This active material combines safety of use and high specific capacitance.

[0009] According to one embodiment, x=0.

[0010] According to one embodiment, M is Nb.

[0011] According to one embodiment, y=0.

[0012] According to one embodiment, M' ' is Mo.

[0013] According to one embodiment, a=0 and b=l.

[0014] According to one embodiment, the compound has the formula Nbi5Mo04oF.

[0015] According to one embodiment, the compound has a crystalline structure in in which M and M' occupy octahedral sites whose vertices are oxygen atoms or surrounding X atoms and M” and M'” occupy tetrahedral sites whose vertices are surrounding oxygen atoms.

[0016] According to one embodiment, the octahedra form parallel planes between them which are connected by the tetrahedra.

[0017] The invention also relates to an electrochemical element comprising: - at least one positive electrode, - at least one negative electrode, which is the electrode as described above.

[0018] According to one embodiment, the positive electrode comprises one or more positive active materials selected from: a) a lithium iron phosphate of formula LixFei yMyPO4 (LFP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Mn, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; b) a lithium manganese phosphate of formula LixMni yMyPO4 (LMP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Fe, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; c) a lithium manganese and iron phosphate of formula: LixMni y zFeyMzPO4 (LMFP) where 0.8 <x<l,2 ; 0,5<l-y-z<l; 0<y+z<0,5 ; 0<y<0,50 et 0<z<0,2 et M est choisi dans le groupe constitué de Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; d) a lithium oxide of nickel, manganese and cobalt of formula Liw(NixMnyCozMt)O2(NMC) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ; e) a lithium oxide of nickel, cobalt and aluminium of formula Liw(NixCoyAlzMt)O2(NCA) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ; f) a compound of formula Lii+xMi.xO2.yFy with cubic crystal structure where 0 <x<0,5 et 0<y<l et M représente un élément choisi dans le groupe constitué de Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd et Sm et des mélanges de ceux-ci ; (g) a lithium nickel manganese oxide (NMX) of formula Lia(Nii_x y zMnxCoyMz)O2 with 0.9 <a<l,l ; 0,60<l-x-y-z<0,80 ; 0<x ; 0<y<0,02 ; 0 <z ; et M étant choisi dans le groupe consistant en Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ga, Ta, Nd, Pr, La et des mélanges de ceux-ci ; h) a lithium oxide of nickel and manganese of formula Liw(NixMnyCozMt)O2 where 1.1 <w<1,6 ; 0<x ; 0,50<y<0,80 ; 0<z<0,02 ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci. (i) a lithium oxide of nickel and manganese of formula LixMn2_y_zM'yM"zO4_ô where M' and M" are chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; M' and M" being different from each other, and 1 <x<1,4 ; 0<y<0,6 ; 0<z<0,2 ; 0<ô<l. Brief description of the figures

[0019] [Fig. 1] represents the variation of the potential of different active materials with respect to the Lr7Li couple during a charge and discharge cycle.

[0020] [Fig.2] represents the alternation of the NbO6 and NbO4F2 octahedral blocks within the crystal structure of the compound with formula NbO5MoO4F.

[0021] [Fig.3] represents the position of molybdenum and oxygen atoms in a MoO4 tetrahedron, the position of niobium and oxygen atoms in an NbO6 octahedron and the position of niobium, oxygen and fluorine atoms in an NbO4F2 octahedron.

[0022] [Fig. 4] shows the voltage variation of the compound with formula Nbi5MoO40F during the first two cycles. Charging and discharging are carried out at room temperature, at C / 10 and D / 10 regimes, respectively. The legend is given from the perspective of using Nbi5MoO40F as a negative material. Thus, charging corresponds to the intercalation of lithium within the Nbi5MoO40F structure, and discharging corresponds to the deintercalation of lithium within the Nbi5MoO40F structure.

[0023] [Fig. 5] represents the voltage variation of an electrochemical element comprising a negative electrode based on Nbi5MoO40F during a 50-cycle cycle. Charging and discharging are carried out at room temperature, at C / 5 and D / 5 regimes respectively. Detailed description of the embodiments Negative electrode:

[0024] The general formula of the compounds is Mi5.xM'xM' ' i yM” 'yO40 aXb in which: M represents one or more elements chosen from Nb, Ta and V, M' represents one or more elements chosen from Ti, Zr, Mo, Cr, As and Sb, M' ' represents one or more elements chosen from Mo and W, M'” represents one or more elements chosen from Cr, V and Te, X represents a halogen, 0 <x<7,5 ; 0 <y<l; 0 <a<5 ; 0 <b<l, the compound satisfying the relation (15-x)*5 + nx + (ly)*6 + my =(40-a)*2 + b ; n and m indicating respectively the average oxidation degrees of M' and M”', the average oxidation degree of M' (respectively M'”) being the average of the oxidation degrees of the elements constituting M' (respectively M'”).

[0025] The elements Nb, Ta and V in M ​​are in the oxidation state +V.

[0026] The elements Mo and W in M” are in the oxidation state +VI.

[0027] The optional substituent elements M' and M”' can be incorporated into the compound of the invention using precursors containing these elements. The precursors and their quantities are chosen by those skilled in the art so as to respect the relationship described above. The oxidation states n and m depend on the precursors chosen and are known to those skilled in the art. - Ti and Zr in M' can be in the oxidation state +IV. - Sb and As in M' can be in the oxidation state +V. - Mo and Cr in M' can be in the oxidation state +VI. - V in M'” can be in the oxidation state +V. - Cr and Te in M' ' ' can be in the oxidation state +VI.

[0028] The compound Mi5M”04o-aXb can exhibit a crystal form that is the monoclinic form of space group C2. MO6 and MO4X2 octahedra are grouped into 3 x 5 octahedral planes sharing vertices in the (ab) plane of the unit cell. The MO4X2 octahedron occupies the center of the 3 x 5 octahedral group. The planes alternate along the b-axis at y = 0 and y = U2 values ​​and are connected to each other between the two y values ​​by M”O4 tetrahedra.

[0029] In a preferred embodiment, X is fluorine, x=0, y=0, a=0 and b=l.

[0030] A preferred example of a compound is Nbi5MoO4oF. It is obtained by heating to a A mixture of the compounds Nb2O5, MoO3, and NbO2F in stoichiometric proportions is heated to a temperature between 900 and 1000°C. The reaction is:

[0031] 7Nb2O5 + MoO3 + NbO2F -> MoNb15O40F

[0032] The synthesis and characterization of this compound are described in the article entitled "Crystal structure of MoNbi5O40F" by J. Galy and S. Andersson published in Acta. Cryst. (1968), B24, 1027.

[0033] Figure 2 partially represents the crystal structure of the compound NbO4F. It shows two types of blocks: a first block of 15 octahedra forming a plane at position z=0 or z=l, and a second block of 15 octahedra forming a plane at position z=l / 2, also composed of 15 octahedra. The octahedron located at the center of each block of 15 octahedra is an NbO4F2 octahedron. Each block has been singled out to facilitate understanding of the crystal structure.

[0034] Figure 3 shows the position of molybdenum and oxygen atoms in a MoO4 tetrahedron, the position of niobium and oxygen atoms in an NbO6 octahedron, and the position of niobium, oxygen, and fluorine atoms in an NbO4F2 octahedron. A block consisting of 3 x 5 octahedra has been isolated to facilitate understanding of the crystal structure.

[0035] Mi5_xM'xM” i yM' ”yO40 aXb may be the only active material of the negative electrode.

[0036] It can also be associated with one or more negatively charged active materials exhibiting a potential of approximately 1.5 V vs. Li+ / Li. Examples include lithia-coated titanium oxides such as compounds with the formula: i) Lix.aMaTiy.bM'b04_c.dXc in which 0 <x<3 ; l<y<2,5 ; 0<a<l ; 0<b<l ; 0<c<2 et -2,5<d<2,5 ; L’indice d représente une lacune en oxygène. L’indice d peut être inférieur ou égal à 0,5, M represents at least one element chosen from the group consisting of Na, K, Mg, Ca, B, Mn, Fe, Co, Cr, Ni, Al, Cu, Ag, Pr, Y and La; M' represents at least one element chosen from the group consisting of B, Mo, Mn, Ce, Sn, Zr, Si, W, V, Ta, Sb, Nb, Ru, Ag, Fe, Co, Ni, Zn, Al, Cr, La, Pr, Bi, Sc, Eu, Sm, Gd, Ce, Y and Eu; X represents at least one element chosen from the group consisting of S, F, Cl and Br. This family includes compounds with the formula Li4Ti50i2, Li2TiO3>Li2Ti3O7 LiTi2O4 and Li2 Na2Ti60i4. Preferably 0.5 <x<3 ; Preferably a<0.5; Preferably b<0.25; Preferably c<0.5. ii) HxTiyO4 in which 0 <x<l ; 0<y<2. Cette famille inclut H2Ti60i3, H2Tii2O25 et TiO2 ; et iii) a mixture of compounds i) and ii).

[0037] Other examples include titanium and niobium oxides, such as compounds with the formula: iv) LixTia_yMyNbb_zM' zO((X+4a+5b) / 2)_c_dXc where 0 <x<5 ; 0<y<l ; 0<z<2 ; l<a<5 ; l<b<25 ; 0,25<a / b<2 ; 0<c<2 et 0 <d<2 ; a-y> 0; bz>0; The index d represents an oxygen vacancy. The index d can be less than or equal to 0.5. M and M' each represent at least one element chosen from the group consisting of Li, Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd and Sm; X represents at least one element chosen from the group consisting of S, F, Cl and Br; This family includes the compounds with the formula TiNb2O7, Ti2Nb2O9 and Ti2NbmO2l).

[0038] Titanium niobium oxide can be partially substituted by vanadium and have the formula LixTii_yMyNb2_(zi+Z2)VziM'Z2O7_c_dXc where 0 <x<5 ; 0<y<l ; 0<zl<0,5 ; 0<z2<0,5 ; 0<c<2 ; 0<d<2 ; M represents one or more elements chosen from the group consisting of Mg, Ca, B, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd and Sm; M' represents one or more elements chosen from the group consisting of Mg, Ca, B, Sc, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd and Sm; X represents one or more elements chosen from the group consisting of S, F, Cl and Br. This family includes compounds with the formula TiNbi>98Vo,o207 and TiNb1.95V0.05O7.

[0039] To obtain the negative active ingredient composition, an ink is prepared by dispersing one or more negative active ingredients, one of which is Mi5_xM'xM”i_yM”'y04o-aXb, and optionally one or more binders and one or more electronically conductive compounds, in a solvent or a mixture of solvents. The solvent(s) may be organic or aqueous. Preferably, it is N-methylpyrrolidone. The binder can be chosen from poly(vinylidene fluoride) (PVDF) and its copolymers, polytetrafluoroethylene (PTFE) and its copolymers, polyacrylonitrile (PAN), poly(methyl or butyl methacrylate), poly(vinyl chloride) (PVC), poly(vinyl formalin), polyester, sequenced polyetheramides, acrylic acid polymers, methacrylic acid, acrylamide, itaconic acid, sulfonic acid polymers, elastomers, and cellulosic compounds such as carboxymethylcellulose (CMC).The elastomers that can be used as binders may be selected from styrene-butadiene (SBR), butadiene-acrylonitrile (NBR), hydrogenated butadiene-acrylonitrile (HNBR). Preferably, said at least one binder is an aqueously dispersible binder, such as polytetrafluoroethylene (PTFE), carboxymethylcellulose (CMC), styrene-butadiene (SBR), butadiene-acrylonitrile (NBR), hydrogenated butadiene-acrylonitrile (HNBR) and polyvinyl alcohol (PVA).

[0040] The electronically conductive material is generally chosen from graphite, carbon black, acetylene black, soot, graphene, carbon fibers, carbon nanotubes or a mixture thereof.

[0041] By varying the amount of solvent incorporated into the mixture, the viscosity of the ink can be varied before it is deposited on a face of a current collector. The negative current collector is a solid or perforated metal strip that can be made of copper or a copper-based alloy, or made of aluminum or an aluminum-based alloy. Preferably, it is made of aluminum or an alloy of Aluminum is used as the base material because it is lighter than copper. Its thickness can range from 3 to 25 µm, preferably from 5 to 8 µm. The ink-coated current collector is dried and then laminated to achieve the correct thickness. After evaporation of the solvent(s), a layer is obtained composed of one or more active materials, the proportions of which are typically: - 85 to 98% or 90 to 98% by mass of one or more negative active ingredients, - 1 to 10% or 1 to 5% by mass of one or more binders, - 0 to 5% by mass or 1 to 5% of one or more electronically conductive materials. Positive electrode:

[0042] The positive electrode includes a current collector, at least one of whose faces is coated with a layer of a composition of positive active materials, which includes one or more active materials and optionally one or more binders and one or more electronically conductive materials.

[0043] The positive current collector is a solid or perforated metal strip which may be made of aluminum or an aluminum alloy or steel or stainless steel. Its thickness may be in the range of 6 to 30 µm or 5 to 20 µm or 10 to 15 µm, preferably 10 to 15 µm.

[0044] The positive active material can be any positive active material known in lithium-ion electrochemical element technology. It can be selected from the following different types or be a mixture thereof: a) a lithium iron phosphate of formula LixFei yMyPO4 (LFP), where 0.8 <x<l,2 ; 0<y<0,6 et m est choisi dans le groupe consistant en al, b, mg, k, si, ca, ti, v, cr, co, cu, mn, ni, zn, y, zr, nb, w, pb, mo, s des mélanges de ceux-ci b) a lithium manganese phosphate of formula LixMni yMyPO4 (LMP), where 0.8 <x<l,2 ; 0<y<0,6 et m est choisi dans le groupe consistant en al, b, mg, k, si, ca, ti, v, cr, co, cu, fe, ni, zn, y, zr, nb, w, pb, mo, s des mélanges de ceux-ci c) a lithium manganese and iron phosphate of formula: LixMni y zFeyMzPO4 (LMFP) where 0.8 <x<l,2 ; 0,5<l-y-z<l; 0<y+z<0,5 0<y<0,50 et 0<z<0,2 m est choisi dans le groupe constitué de al, b, mg, k, si, ca, ti, v, cr, co, cu, ni, zn, y, zr, nb, w, pb, mo, s des mélanges ceux-ci d) a lithium oxide of nickel, manganese and cobalt of formula Liw(NixMnyCozMt)O2(NMC) where 0.9 <w<l,l ; 0<x 0<y 0<z 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ta, ga, nd, pr, la et des mélanges ceux-ci e) a lithium oxide of nickel, cobalt and aluminium of formula Liw(NixCoyAlzMt)O2(NCA) where 0.9 <w<l,l ; 0<x 0<y 0<z 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, mn, fe, cu, zn, y, zr, nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La and mixtures thereof; f) a compound of formula Lii+xMi_xO2_yFy with cubic crystal structure where 0 <x<0,5 et 0<y<l m représente un élément choisi dans le groupe constitué de na, k, mg, ca, b, sc, ti, v, cr, mn, fe, co, ni, cu, zn, al, y, zr, nb, mo, ru, ag, sn, sb, ta, w, bi, la, pr, eu, nd sm des mélanges ceux-ci ; g) a lithium nickel manganese oxide (NMX) of formula Lia(Nii_x_y_zMnxCoyMz)O2 with 0.9 <a<l,l ; 0,60<l-x-y-z<0,80 0<x 0<y<0,02 0<z et m étant choisi dans le groupe consistant en al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ga, ta, nd, pr, la des mélanges de ceux-ci h) a lithium oxide of nickel and manganese of formula Liw(NixMnyCozMt)O2 where 1.1 <w<1,6 ; 0<x 0,50<y<0,80 0<z<0,02 0<t m étant choisi dans le groupe constitué de al, b, mg, si, ca, ti, v, cr, fe, cu, zn, y, zr, nb, w, mo, s, sr, ce, ta, ga, nd, pr, la et des mélanges ceux-ci. i) a lithium oxide of nickel and manganese of formula LixMn2.y.zM'yM"zO4.ô where M' and M" are chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; M' and M" being different from each other, and 1 <x<1,4 ; 0<y<0,6 0<z<0,2 0<ô<l.

[0045] Preferably, it is a compound of type c), that is to say a lithium manganese and iron phosphate of formula: LiMnO2 / 3FeO2PO4(LMFP). Typical formulas of lithium manganese and iron phosphate are LiMnO2 / 3FeO2PO4, LiMnO2 / 3FeO2PO4, LiMnO2 / 3FeO2PO4, and LiMnO2 / 5FeO2PO4.

[0046] An ink is prepared by dispersing one or more positive active substances in a solvent or a mixture of several solvents. Optionally, a binder and an electronically conductive material are added to the dispersion. By varying the amount of solvent incorporated into the mixture, the viscosity of the ink can be varied before it is deposited on a face of the current collector. The ink-coated current collector is dried and then laminated to adjust its thickness. After evaporation of the solvent(s), a layer is obtained composed of one or more active substances, the proportions of whose various constituents are typically: - 80 to 98% or 90 to 95% by mass of one or more active ingredients, - 1 to 10% or 2 to 5% by mass of one or more binders, - from 0.1 to 10% or from 2 to 5% by mass of one or more electronically conductive materials.

[0047] The binder(s) may be chosen from the same list as that described in relation to the negative electrode, without necessarily being the same as those of the negative electrode. Similarly, the electronically conductive material(s) may be chosen from the same list as that described in relation to the negative electrode, without necessarily being- necessarily the same as those of the negative electrode. Electrolyte:

[0048] The electrolyte can be in solid, liquid or gel form.

[0049] a) Solid electrolyte: It may be a lithium ion-conducting compound, chosen for example from lithium ion-conducting oxides and lithium ion-conducting sulfides. The electrolyte may also be a lithium ion-conducting polymer, such as polyethylene oxide (PEO), polyphenylene sulfide (PPS), and polycarbonate.

[0050] b) Liquid electrolyte: It consists of one or more organic solvents in which one or more lithium salts are dissolved. Organic solvents: The organic solvent(s) can be chosen from linear alkyl carbonates, cyclic alkyl carbonates, linear ethers and cyclic ethers. Linear alkyl carbonate can be selected from the group consisting of dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and propyl methyl carbonate (PMC). Dimethyl carbonate (DMC) and ethyl methyl carbonate (EMC) are particularly preferred. Linear carbonate can represent 50–100%, 60–90%, or 70–80% by volume of the total volume of linear or cyclic alkyl carbonate(s). At least one linear alkyl carbonate may be used in combination with one or more cyclic alkyl carbonates. Examples of cyclic alkyl carbonates include ethylene carbonate (EC), propylene carbonate (PC), and butylene carbonate (BC). Ethylene carbonate (EC), propylene carbonate (PC), and mixtures thereof are particularly preferred. The cyclic carbonate may constitute 1 to 50%, 10 to 40%, or 20 to 30% by volume of the total volume of the linear or cyclic alkyl carbonate(s).

[0051] Lithium salt: The nature of lithium salt is not particularly limited. Examples include lithium hexafluorophosphate LiPF6, lithium hexafluoroarsenate LiAsF6, lithium hexafluoroantimonate LiSbF6, lithium tetrafluoroborate LiBF4, lithium perchlorate LiC104, lithium trifluoromethanesulfonate LiCF3SO3, lithium bis(fluorosulfonyl)imidide Li(FSO2)2N (LiFSI), lithium bis(trifluoromethanesulfonyl)imidide LiN(CF3SO2)2 (LiTFSI), lithium tris(fluoromethanesulfonyl)methylide LiC(CF3SO2)3 (LiTFSM), lithium bis(pentafluoroethylsulfonyl)imidide LiN(C2F5SO2)2 (LiBETI), lithium 4,5-dicyano-2-(trifluoromethyl)imidazolide (LiTDI), and lithium bis(oxalato)borate (LiBOB). lithium difluoro(oxalato)borate (LIDFOB), Lithium tri(pentafluoroethyl)trifluorophosphate LiPF3(CF2CF3)3 (LiFAP), lithium difluorophosphate LiPO2F2 and mixtures thereof. Preferably, this is LiPF6. The concentration of said at least one lithium salt may range from 0.75 to 1.5 mol.L*. Preferably, it ranges from 1 to 1.5 mol.L*. Even more preferably, it is approximately equal to 1 mol.L*.

[0052] cl Gelled electrolyte: It is obtained by impregnating a polymer with a liquid mixture comprising at least one lithium salt and at least one organic solvent. The lithium salt and the organic solvent may be chosen from the examples of lithium salts and organic solvents described above in relation to the liquid electrolyte. Separator:

[0053] A separator is generally interposed between a negative electrode and a positive electrode to prevent potential short circuits. It prevents electrical contact between a negative electrode and a positive electrode but nevertheless allows the transport of ions between these two electrodes. The separator material can be selected from the following materials: a polyolefin, for example polypropylene and polyethylene, a polyester, glass fibers bonded together by a polymer, polyimide, polyamide, polyaramid, polyamideimide, and cellulose. The polyester can be selected from polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Advantageously, the polyester, polypropylene, or polyethylene contains or is coated with a material selected from the group consisting of a metal oxide, a carbide, a nitride, a boride, a silicide, and a sulfide. This material can be SiO2 or Al2O3.The separator can be coated with an organic coating, for example comprising an acrylate or PVDF or P(VdF-HFP). A preferred separator is made of polyethylene or is made of a combination of three layers which are polypropylene PP / polyethylene PE / polypropylene PP.

[0054] The electrochemical element is manufactured in a conventional manner. It can be in prismatic, cylindrical, pocket or button format. Example

[0055] The electrochemical characterization of Nbi5MoO4oF was carried out using an electrochemical half-element, i.e., with a counter electrode made of metallic lithium. The electrochemical half-element underwent two charge / discharge cycles ("formation") at room temperature under C / 10 and D / 10 conditions. It then underwent 50 cycles at room temperature under C / 5 and D / 5 conditions.

[0056] Figure 1 shows that Nbi5MoO4oF has an average potential of approximately 1.7 V vs. Li+ / Li, which is sufficiently far from the potential of Li+ / Li to reduce the risk of dendrite formation.

[0057] Fig. 4 shows a first charge mass capacity of approximately 250 mAh / g.

[0058] Figure 5 shows a reversible capacity of approximately 200 mAh / g at the start of cycling. therefore higher than that of Li4Ti5Oi2 (170 mAh / g).

[0059] Nbi5Mo04oF therefore meets the criteria of safety of use, high capacity and suitability for cycling.

Claims

Demands

1. Electrode comprising: - a current collector, - an active material composition deposited on at least one face of the current collector and comprising an active material which is a compound of formula Mi5_xM'xM”i_yM'”y04o-aXb in which: M represents one or more elements selected from Nb, Ta and V, M' represents one or more elements selected from Ti, Zr, Mo, Cr, As and Sb, M” represents one or more elements selected from Mo and W, M”' represents one or more elements selected from Cr, V and Te, X represents a halogen, 0 <x<7,5 ; 0<y<l; 0<a<5; 0<b<l, le composé satisfaisant la relation (15-x)*5 + nx + (l-y)*6 + my =(40-a)*2 + b; n et m indiquant respectivement les degrés d’oxydation moyens de M’ et de M”’.

2.

3.

4.

5. Electrode according to claim 1, wherein x=0. Electrode according to claim 1 or 2, wherein M is Nb. Electrode according to any one of the preceding claims, wherein y=0. Electrode according to any one of the preceding claims, wherein M” is Mo.

6. Electrode according to any one of the preceding claims, in which a=0 and b=l.

7. Electrode according to any one of the preceding claims, wherein the compound has the formula NbisMoO^F.

8. Electrode according to any one of the preceding claims, wherein the compound has a crystalline structure in which M and M' occupy octahedral sites whose vertices are oxygen atoms or surrounding X atoms and M” and M’” occupy tetrahedral sites whose vertices are surrounding oxygen atoms.

9. Electrode according to claim 8, wherein the octahedra form parallel planes between them which are connected by the tetrahedra.

10. Electrochemical element comprising: - at least one positive electrode, - at least one negative electrode which is the electrode according to one of the preceding claims.

11. Electrochemical element according to claim 10, wherein the positive electrode comprises one or more positive active materials selected from: a) a lithium iron phosphate of formula LixFei yMyP04 (LFP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Mn, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; b) a lithium manganese phosphate of formula LixMni yMyP04 (LMP), where 0.8 <x<l,2 ; 0<y<0,6 et M est choisi dans le groupe consistant en Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Fe, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; c) a lithium manganese and iron phosphate of formula: LixMni y zFey MzPO4(LMFP) where 0.8 <x<1,2 ; 0,5<l-y-z<l; 0<y+z<0,5 ; 0<y<0,50 et 0<z<0,2 et M est choisi dans le groupe constitué de Al, B, Mg, K, Si, Ca, Ti, V, Cr, Co, Cu, Ni, Zn, Y, Zr, Nb, W, Pb, Mo, S et des mélanges de ceux-ci ; d) a lithium oxide of nickel, manganese and cobalt of formula Liw(NixMnyCozMt)O2(NMC) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ; e) a lithium oxide of nickel, cobalt and aluminium of formula Liw(NixCoyAlzMt)O2(NCA) where 0.9 <w<l,l ; 0<x ; 0<y ; 0<z ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Mn, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci ; f) a compound of formula Lii+xMi.xO2.yFy with cubic crystal structure where 0 <x<0,5 et 0<y<l et M représente un élément choisi dans le groupe constitué de Na, K, Mg, Ca, B, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Y, Zr, Nb, Mo, Ru, Ag, Sn, Sb, Ta, W, Bi, La, Pr, Eu, Nd et Sm et des mélanges de ceux-ci ; g) a lithium nickel manganese oxide (NMX) of formula Lia(Nii.xyzMnxCoyMz)O2 with 0.9 <a<l,l ; 0,60<l-x-y-z<0,80 ; 0<x ; 0<y<0,02 ; 0<z ; et M étant choisi dans le groupe consistant en Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ga, Ta, Nd, Pr, La and mixtures of these; h) a lithium oxide of nickel and manganese of formula Liw(NixMnyCoz Mt)O2 where 1.1 <w<1,6 ; 0<x ; 0,50<y<0,80 ; 0<z<0,02 ; 0<t ; M étant choisi dans le groupe constitué de Al, B, Mg, Si, Ca, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, W, Mo, S, Sr, Ce, Ta, Ga, Nd, Pr, La et des mélanges de ceux-ci. (i) a lithium oxide of nickel and manganese of formula LixMn2_y_zM'yM"zO4_ô where M' and M" are chosen from the group consisting of B, Mg, Al, Si, Ca, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb and Mo; M' and M" being different from each other, and 1 <x<1,4 ; 0<y<0,6 ; 0<z<0,2 ; 0<ô<l.

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