Electrode for an electrochromic system and electrochromic system containing said electrode

Abstract

The invention relates to an electrode, in particular a counter-electrode, for an electrochromic device, comprising a lithium, tungsten and nickel oxide in which the atomic ratio of nickel to tungsten is between 0.9 and 1.1, said oxide crystallizing in the orthorhombic system, said lithium, tungsten and nickel oxide preferably fulfilling the formulation LixNi2W2O9, where x is between 0 and 2, endpoints included.

Description

Description Title of the invention: ELECTRODE FOR ELECTROCHROMIC SYSTEM AND ELECTROCHROMIC SYSTEM CONTAINING SAID ELECTRODE

[0001] [The present invention relates to the field of electrochemical devices with electrically controllable optical and / or energetic properties, commonly called "electrochromic devices". More particularly, the invention relates to optical systems integrating such electrochromic devices as well as to the associated manufacturing methods. [2] Electrochromic devices have certain characteristics that can be modified under the effect of an appropriate electrical supply, between a clear state and a tinted state, in particular transmission, absorption, reflection in certain wavelengths of electromagnetic radiation, in particular in the visible and / or infrared, or even light diffusion. The variation in transmission generally occurs in the optical domain (infrared, visible, ultraviolet) and / or in other domains of electromagnetic radiation, hence the name device with variable optical and / or energy properties, the optical domain not necessarily being the only domain concerned. [3] From a thermal point of view, glazing whose absorption can be modified in at least part of the solar spectrum makes it possible to control solar gain inside rooms or passenger compartments / compartments when they are fitted as exterior glazing for buildings or windows of means of transport such as cars, trains, planes, and to avoid excessive heating of these in the event of strong sunlight. [4] Optically, they allow control of the degree of vision, which helps to avoid glare when they are fitted as exterior glazing in strong sunlight. They can also have a particularly interesting shutter effect, both as exterior glazing and if they are used as interior glazing, for example to equip interior partitions between rooms (offices in a building), or to isolate compartments in trains or airplanes for example. [5] From a structural point of view, and in a known manner, an electrochromic stack comprises two electrodes interposed between two transparent electroconductive layers. At least one of these electrodes comprises an electrochromic material which, by definition, is suitable for reversibly and simultaneously inserting ions and electrons, the oxidation states corresponding to the inserted and deinserted states being of distinct coloration, one of the states having a higher light transmission than the other. The insertion or deinsertion reaction is controlled by means of the two transparent conductive layers whose electrical supply is ensured by a current generator or a voltage generator. [6] A first electrode, called the working electrode, is made of a cathodic electrochromic material suitable for capturing ions when a voltage is applied to the terminals of the electrochromic system. The tinted state of the working electrode corresponds to its most reduced state. [7] Associated with this working electrode is a second electrode, called the anodic counter-electrode, which is also capable of reversibly inserting cations, symmetrically with respect to the working electrode. In other words, this counter-electrode is thus adapted to release ions when a voltage is applied to the terminals of the electrochromic system. This counter-electrode consists of a layer that is preferably neutral in color, or at least slightly colored when the working electrode is in the clear state, and preferably has a color in the oxidized state so as to increase the total contrast of the electrochromic stack, between its tinted state and its clear state. [8] The working electrode and the counter electrode are separated by an interfacial region commonly called "electrolyte" (in English: lon-Conductor (IC)) having a dual function of ionic conductor and electrical insulator, which can however be optional. The ionically conductive layer therefore prevents any short circuit between the working electrode and the counter electrode. It also allows the two electrodes to retain a charge and thus maintain their clear and tinted states. [9] According to a particular embodiment, such an electrolyte is formed by deposition between the working electrode and the counter-electrode of a separate intermediate layer. The boundaries between these three layers are defined by abrupt changes in composition and / or microstructure. Such electrochromic stacks therefore have at least three distinct layers separated by two distinct abrupt interfaces.

[0010] Alternatively, the working electrode and the counter electrode are deposited one above the other and generally in contact with each other, and a transition region having the function of an electrolyte is formed only subsequently, by migration of components within the electrodes during the manufacturing process and in particular during the heating phases of the stack.

[0011] On either side of the electrodes are arranged the two aforementioned conductive layers as illustrated in Figure 1 attached.

[0012] Within the electrochromic device, two distinct sub-assemblies are thus distinguished: a cathode sub-assembly comprising the working electrode and an anodic sub-assembly comprising the counter-electrode.

[0013] The choice of material used as a counter-electrode is of particular importance in an electrochromic application. It must of course be stable during successive charge and discharge cycles. It is also necessary for this material to have the highest possible Li+ / Li potential. Such a high potential helps to ensure the efficiency of the system. More specifically, this increase in potential ultimately allows the electrochromic device as a whole to operate at a higher potential and therefore significantly reduces the time required to switch the device.

[0014] Application WO2014 / 143410 discloses a material constituting an anodic layer comprising lithium, nickel and an element chosen from tungsten (W) and molybdenum (Mo), in which the atomic ratio (Mo+W) / (Mo+W+Ni) is between 0.025 and 1. The examples in this publication describe compounds with an atomic ratio Ni / W much higher than 1. Electrodes obtained with such compounds, as reported in Table 3 of this publication, have a potential between 2.88 and 3.56 V vs Li + / Li.

[0015] In particular, on a large electrochromic device, i.e. incorporating the electrochromic system described above on a large support (glazing), the switching speed is limited by the charge loss along the surface of said device. This charge loss is due to the limited conductivity of the materials making up the electrochromic system. Operating such an electrochromic device at a higher voltage reduces the impact of this charge loss on the voltage distribution across the entire surface of the device, a higher voltage resulting in a lower relative voltage drop at the center of the device. The device then switches more uniformly and the final state is obtained more quickly.

[0016] More particularly, in order to fulfill the objectives and problems previously described, the present invention relates to an electrode, in particular a counter-electrode, for an electrochromic device, comprising, preferably consisting of, an oxide of tungsten, nickel and optionally lithium, in which the atomic ratio of nickel and tungsten is between 0.9 and 1.1, said oxide crystallizing in an orthorhombic reticular system.

[0017] Preferably, said electrode is made up of elements other than Li, Ni, W, and O, other than in the form of unavoidable impurities.

[0018] According to preferred but non-limiting embodiments of the present invention, which can of course be combined with each other where appropriate:

[0019] - the atomic ratio of oxygen to nickel (O / Ni) in said oxide is between 4.0 and 5.0, in particular between 4.2 and 4.8.

[0020] - the atomic ratio of oxygen to tungsten (O / W) in said oxide is between 4.0 and 5.0, in particular between 4.2 and 4.8.

[0021] -said lithium, tungsten and nickel oxide corresponds to the formulation LixNi2W20g, with x between 0 and 2, limits included, preferably between 0 and 2, 0 excluded and 2 included.

[0022] - x is between 0.1 and 2 inclusive, preferably between 1 and 2 inclusive.

[0023] - said oxide crystallizes in the space group Pbcn.

[0024] - said oxide has the following lattice parameters: - a = 8.69 A ± 0.10 A - b = 5.06 A ± 0.10 A and - c = 14.34 A ± 0.10 A.

[0025] - said oxide has a lamellar structure, a succession of sheets of NiOe and WOe octahedra, spaced by planes in which the lithium atoms are inserted, the distance between two closest tungsten atoms belonging to two successive sheets of octahedra being preferably greater than 3 A, or even greater than 4 A.

[0026] The invention also relates to an anodic subassembly for an electrochromic system, said anodic subassembly being adapted to be deposited above a substrate with a glass function, comprising an electrode, in particular a counter electrode, as described previously.

[0027] - Said anode sub-assembly may in particular include: - a transparent conductive layer (2B), - a counter-electrode (5) consisting of an electrode as previously described and arranged above said first transparent conductive layer (2B).

[0028] - In said anode subassembly, according to a first embodiment, said counter-electrode is in the form of a layer in contact with the transparent conductive layer.

[0029] - According to another embodiment, the counter-electrode is in the form of a layer in contact with the transparent conductive layer, said layer being constituted by crystallized particles of said tungsten and nickel oxide dispersed in an organic or inorganic matrix.

[0030] The invention further relates to an electrochromic system incorporating a glass-functional substrate, and comprising an electrode as described above, in particular an anode subassembly described above.

[0031] An electrochromic system advantageously incorporates, from the surface of said substrate: - a cathode subassembly successively comprising a first transparent conductive layer and a working electrode; - an anode subassembly as previously, in particular successively comprising a counter-electrode comprising said lithium, tungsten and nickel oxide, and a second transparent conductive layer arranged below said counter-electrode, - Lithium (Li) ions introduced into said electrochromic system.

[0032] Preferably, the electrochromic system described above further comprises a separate layer of an ionic conductor interposed between the electrode and the counter-electrode.

[0033] In such an electrochromic system, said working electrode advantageously comprises a tungsten oxide, in particular WO3, optionally doped with an element chosen from Ni, Nb, Mo, Ta, Ti, V, Zn, Zr, or alternatively a vanadium oxide, in particular V2O5.

[0034] The thickness of the working electrode is typically between 100 and 1500 nm.

[0035] The thickness of the counter electrode is generally between 100 and 1500 nm.

[0036] Finally, the present invention relates to glazing incorporating an electrochromic system as previously described, said glazing being suitable for use as building glazing, in particular exterior glazing of internal partitions or glass doors, or as glazing equipping internal partitions or windows of means of transport such as trains, planes, cars, boats.

[0037] Such glazing may comprise at least two glass substrates, incorporating the electrochemical system described above.

[0038] Note that throughout the text, the deposition of a layer above or below another does not necessarily mean that these two layers are in direct contact with each other. The terms "above" and "below" below" here refers to the order of arrangement of these different elements, chosen arbitrarily in relation to the surface of the substrate with a glass function. Alternatively, such an order of arrangement can therefore be reversed, in relation to this same substrate. In addition, two layers deposited one above the other can, for example, be physically separated by one or more intermediate layers. In the same spirit, the term "between" does not necessarily mean that three designated elements are in direct contact with each other.

[0039] By substrate with a glass function we mean of course a glass substrate but also alternatively any rigid plastic material, i.e. one that can provide the support function for the electrochromic system in a glazing, such as PMMA or polycarbonates. However, the substrate is preferably made of glass.

[0040] According to preferred embodiments, the working electrode is deposited by magnetron. Alternatively, the deposition is carried out by liquid means.

[0041] According to a particular embodiment, said working electrode is at least composed of a Tungsten oxide (WOx) doped with at least one transition metal element Y chosen from the group comprising Niobium (Nb), Molybdenum (Mo), Vanadium (Va), Tantalum (Ta), Titanium (Ti), Nickel (Ni), Zinc (Zn), Zirconium (Zr) as described in application WO2021 / 123267.

[0042] The invention also relates to an electrochromic system suitable for being deposited above a substrate with a glass function, and comprising: - a cathode subassembly as described above, - a counter-electrode arranged above said cathode sub-assembly, - a second transparent conductive layer arranged above said counter-electrode, - Lithium (Li) ions introduced into said electrochromic system, - and preferably a separate layer of an ionic conductor interposed between the electrode and the counter-electrode.

[0043] The invention also relates to an electrochromic system suitable for being deposited above a substrate with a glass function, and comprising: - a second transparent conductive layer arranged above said substrate, - a counter-electrode arranged above said second transparent conductive layer, - a cathode subassembly such as that described above, arranged above said counter-electrode, - Lithium (Li) ions introduced into said electrochromic system, - and preferably a separate layer of an ionic conductor interposed between the electrode and the counter-electrode.

[0044] When manufacturing the electrochromic system, it is thus possible to reverse the order of deposition of the stack on the substrate, and thus to alternately deposit the counter-electrode above the working electrode, or the working electrode above the counter-electrode.

[0045] Throughout the text, the step of introducing Lithium (Li) ions into said electrochromic system can be carried out in different ways. Preferably, one or more distinct layers of lithium are intercalated within the electrochromic system. The Lithium ions are subsequently caused to diffuse within the electrochromic stack, spontaneously and / or under the effect of a rise in temperature.

[0046] According to a particular embodiment, said counter-electrode is at least composed of a Tungsten-Nickel oxide (NiW x O z ), preferably doped with at least one transition metal element.

[0047] According to a particular embodiment, - the thickness of the working electrode (3) is between 100 and 1500 nm, preferably between 150 and 1000 nm, preferably between 200 and 700 nm, preferably between 300 and 500 nm, preferably between 350 and 450 nm, and / or - the thickness of the counter-electrode (5) is between 100 and 1500 nm, preferably between 150 and 500 nm, preferably between 200 and 350 nm, preferably between 225 and 300 nm, preferably between 260 and 280 nm.

[0048] The invention also covers obtaining an electrochromic device by assembling a hardened cathode subassembly on the one hand, and an anodic subassembly on the other hand. Such an anodic subassembly comprises at least one counter-substrate above which a second transparent conductive layer and a counter-electrode are deposited. Preferably, said anodic subassembly is thermally hardened.

[0049] The invention further relates to glazing incorporating such a toughened electrochromic system, said glazing being suitable for use as building glazing, in particular exterior glazing for internal partitions or glass doors, or as glazing equipping internal partitions or windows of means of transport such as trains, planes, cars and boats.

[0050] Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments, given as simple illustrative and non-limiting examples, and from the appended figures, among which:

[0051] [Figure 1] Figure 1 is a schematic representation of an electrochromic system according to a particular embodiment of the invention.,

[0052] [Figure 2] Figure 2 is a graph describing the potential of an electrode according to the invention comprising the crystalline compound Li xNi2W20g, compared to that of an electrode according to the prior art WO2014 / 143410 and comprising the material Li x Neither y WOz with y>2

[0053] [Figure 3] Figure 3 is a graph in which the potential difference between the counter electrode and the working electrode in an electrochromic device according to the invention as shown in Figure 1 is reported, in which the transparent conductive layers are made of ITO, the working electrode is made of WO3 and the solid electrolyte layer is made of LiSiO x The counter electrode according to the invention comprises the crystalline compound Li x Ni2W20g and that according to the prior art the material Li x NiyWOz with y>2.

[0054] [Figure 4] Figure 4 depicts the discharge capacity of the electrochemical system as successive charge and discharge cycles of an electrode according to the invention proceed.

[0055] [Figure 5] Figure 5 is a representation of the structure of the Li electrode material x Ni2W20g according to the invention as obtained by Rietveld analysis.

[0056] Unless otherwise indicated, reference numbers used in Figure 1 and reported in this description represent similar or identical elements.

[0057] The various elements illustrated by the figures are not necessarily represented to actual scale, the emphasis being more on representing the general operation of the invention.

[0058] Several particular embodiments of the invention are presented below. It is understood that the present invention is in no way limited by these particular embodiments and that other embodiments can be perfectly implemented.

[0059] According to a particular embodiment, and as illustrated by Figure 1, the invention relates to an electrochromic system (8) deposited on a substrate (1) with a glass function and comprising, in their order of deposition: a first transparent conductive layer (2A), preferably made of indium-tin oxide (ITO), a working electrode (3) made of tungsten oxide (WOx) which can be doped preferably by an element chosen from Ni, Nb, Mo, Ta, Ti, V, Zn, Zr, an electrolyte (4), for example comprising or consisting of a silicon and lithium oxide (LiSiOx), a counter-electrode (5) comprising or consisting of a lithium nickel and tungsten oxide according to the invention of general formulation Li x Ni2W20g, 0 <x<2, et une deuxième couche conductrice transparente (2B) en oxyde d'indium-étain (ITO).

[0060] It should be noted that Lithium (Li) ions have at this stage already been introduced into said electrochromic system by deposition of two separate layers of Lithium, the first between the working electrode and the electrolyte, the second between the counter-electrode and the second transparent conductive layer, each deposition being followed by a heating step in order to cause the diffusion of the Lithium ions into the electrochromic stack.

[0061] According to a preferred embodiment, at least a portion and preferably all of the layers forming the electrochromic stack are deposited by magnetron. According to an alternative embodiment, at least part of these layers is deposited using an alternative process, for example via liquid deposition.

[0062] In operation, the anodic material of the electrode according to the invention (preferably Li xNi2W20g) is capable of exchanging lithium electrochemically. This lithium exchange is followed by the change of the oxidation state of the material. In the reduced state (i.e. with a maximum of Li in the crystal lattice, e.g. x=2), the light absorbance of the material is minimal. In the oxidized state (i.e. with a minimum of Li in the crystal lattice, e.g. 1 <x<2), l'absorbance optique du matériau est maximale dans le visible. On parle alors de coloration anodique. Ce changement de coloration pourrait provenir du changement d'état d'oxydation des atomes de nickel : N i 2+ / Neither 3+ , the Ni species 3+ absorbing more visible light than Ni species 2+ .

[0063] According to an alternative embodiment not illustrated, the order of deposition of the electrochromic stack on the substrate can be reversed, so that it is presented in the following deposition order: a first transparent conductive layer (2A) of indium-tin oxide (ITO), a counter-electrode (5) of lithium nickel-tungsten oxide according to the invention, an electrolyte (4), for example comprising or consisting of a silicon and lithium oxide such as LiSiOx, a working electrode (3) of optionally doped tungsten oxide (WOx), and a second transparent conductive layer (2B) also of indium-tin oxide (ITO). The working electrode is then deposited above the counter-electrode.

[0064] According to these two alternative embodiments, the first transparent conductive layer and the working electrode form a cathodic subassembly (6), while the counter-electrode and the second transparent conductive layer form an anodic subassembly (7).

[0065] A preferred electrochromic device according to the invention is therefore entirely solid and consists of a stack of thin film layers on a transparent substrate (glass or plastic). At least 5 layers make up the stack - A first transparent conductive layer (ITO, SnO2:F, etc.) - A working electrode layer (WO3 possibly doped, TiO2, V2O5, etc.) - A layer of ionic conductor (LiSiOx, etc.) - A counter-electrode layer according to the invention - A second transparent conductive layer (ITO, SnO2:F, etc.).

[0066] Additional layers can be used: - Several layers of different compositions inside the working and counter electrode layers. - Layers to improve optical properties (anti-reflection, etc.) between the substrate and other layers or at the interface with air. - Encapsulation layer at the interface with air - Buffer layers between the electrodes and the transparent conductive layers.

[0067] According to a possible alternative according to the invention, the electrochromic device can be made from two transparent substrates (glass or plastic) on which at least two layers are deposited, which constitute the constituent elements of said device.

[0068] The two constituent elements described above are assembled with the materials constituting the electrode and the counter-electrode opposite each other using an organic intermediate layer (polymer gel) which acts as an ionic conductor. On the first substrate, the deposited layers are at least: - a first transparent conductive layer (ITO, SnO2:F, etc.) - a working electrode layer (e.g. possibly doped WO3, TiO2, V2O5, etc.). On the second substrate, the two deposited layers are at least: - A second transparent conductive layer (ITO, SnO2:F, etc.) - A counter-electrode layer according to the present invention. The interlayer gel may contain at least one polymer, a lithium salt, a solvent for dissolving the salt and as a plasticizer for the polymer.

[0069] The experimental examples described below make it possible to highlight certain of the technical advantages conferred by an electrode according to the invention, without however limiting the scope of the claims.

[0070] The synthesis of the material according to the invention is carried out as follows: The Li2Ni2W2O9 powder is synthesized by ceramic synthesis from nickel oxide powder (NiO, Sigma-Aldrich, 99%), tungsten oxide (WO3, Alfa Aesar, 99.8%), and lithium carbonate (Li2CO3, Sigma-Aldrich, > 99.0%). The powders are mixed in an agate mortar before being transferred to a steel jar with two steel balls. The whole is inserted into a mechanical mill (SPEX SamplePrep 8000M Mixer / Mill) for high-energy mechanical grinding for 30 min. The powder obtained is placed in an alumina crucible and placed in a Carbolite CWF 1200 muffle furnace. The powder is heated in air at a rate of 5°C / min until it reaches 650°C and is then kept in the furnace for 12 hours at this temperature to ensure the decarbonation of the lithium carbonate. Then the powder is annealed at 700°C for 24 hours. The powder obtained is again mechanically ground for 30 minutes and kept at 700°C for 24 hours to ensure a complete reaction.

[0071] Galvanostatic charge-discharge experiments were first performed using button cells obtained from the synthesized powder, in a two-electrode configuration. To measure the potential of one electrode comprising Li2Ni2W2O9 according to the invention, it was mixed with Super P carbon black (20 wt%), the other electrode being made of lithium metal. An aluminum foil and a stainless steel plate were used as current collectors at the positive and negative electrodes, respectively. Two layers of Whatman GF / D glass fiber filters were used as a separator between the two electrodes. The electrolyte was a 1 M solution of lithium hexafluorophosphate (LiPF6) in a 1:1:4 vol% mixture of ethylene carbonate (EC), propylene carbonate (PC) and dimethyl carbonate (DMC).

[0072] Measurements are performed using a BioLogic BCS-805 battery cycler, and data acquired using EC-Lab. Cells are cycled between 2.5 and 5.0 V vs Li + / Li, at a current density of 10 mA. g -1 , at room temperature and pressure. Three button cells are cycled under the same conditions in order to verify the repeatability of the electrochemical behavior and to obtain a certain statistical dispersion of these measurements.

[0073] For comparison, the same galvanostatic charge-discharge experiments are carried out in the same two-electrode configuration, but the potential of one electrode, this time made of Li, is measured. x NiyWO z with y>2 according to prior art WO2014 / 143410.

[0074] In Figure 2 we have reported the potentials (in V vs Li+ / Li) of the electrode comprising the material Li2Ni2W2O9 according to the present invention (dotted line curve) and of the standard electrode previously described as a function of the charge exchanged during the passage of the material from a clear state, i.e. not or little absorbent of visible light (Li2Ni2W20gj to a dark state, i.e. more absorbent, corresponding to the disinsertion of lithium ions and therefore a formulation Li2-xNi2W20g with x<2).

[0075] The results reported in Figure 2 show an essential advantage of the present invention: it can be seen that an electrode comprising the Li2Ni2W20g material according to the present invention reacts at a very high potential compared to Li / Li+, of the order of 4.5V to 5.0V.

[0076] Such a property makes it possible to envisage increased efficiency of the electrochromic system according to the invention. More particularly, this increase in potential ultimately allows the operation of the electrochromic device as a whole at a higher potential and consequently to significantly reduce the time required to switch it.

[0077] An electrochromic device is constructed using the counter electrode according to the invention, on the model described previously in relation to figure 1 and the same device but using an electrochromic device using the counter electrode according to the prior art described previously.

[0078] In Figure 3, the potential differences between the counter electrode and the working electrode are plotted for an electrochromic system that uses one or the other of the two counter electrodes. It can be seen that the potential difference is much higher on a device according to the invention, which makes it possible to significantly reduce the time required to switch the system according to the invention.

[0079] Figure 4 depicts the discharge capacity of an electrode according to the invention as previously described over successive charge and discharge cycles. It can be seen that this capacity does not change over successive cycles, which guarantees the durability of said electrode in an electrochromic application.

[0080] X-ray diffraction and neutron diffraction analyses are performed on the Li oxide material x Ni2W20g. From the diffractograms and by Rietveld method, its structure is determined. The material crystallizes according to an orthorhombic cell in the space group Pbcn and its elementary cell presents after refinement of the lattice parameters a = 8.69 A; b = 5.06 A and c = 14.34 A.

[0081] The structure obtained for the oxide is shown in Figure 5. A lamellar structure is observed comprising, along the c axis, a succession of NiOe and WOe octahedral sheets, spaced apart by planes in which the lithium atoms (ions) are inserted. According to the invention, the distance between two closest tungsten atoms belonging to two successive octahedral sheets is of the order of 4.13 A (see attached Figure 5).

[0082] Furthermore, X-ray diffraction shows that the oxide material also does not show any structural changes as successive charge and discharge cycles proceed.

[0083] Although particular embodiments of the present invention have been illustrated and described, it is obvious that various other changes and modifications may be made within the spirit and scope of the invention. The present text is therefore intended to cover in the appended claims all modifications falling within the scope of the present invention.

Claims

Claims 1. [Electrode, in particular counter-electrode, for electrochromic device, comprising an oxide of tungsten, nickel and optionally lithium in which the atomic ratio between nickel and tungsten (Ni / W) is between 0.9 and 1.1, said oxide belonging to the orthorhombic crystal system.

2. Electrode according to claim 1, wherein the atomic ratio of oxygen to nickel (O / Ni) in said oxide is between 4.0 and 5.0, in particular between 4.2 and 4.

8.

3. An electrode according to claim 1 or 2, wherein the atomic ratio of oxygen to tungsten (O / W) in said oxide is between 4.0 and 5.0, especially between 4.2 and 4.

8.

4. Electrode according to one of the preceding claims, in which said lithium, tungsten and nickel oxide corresponds to the formulation Li x Ni2W20g, with x between 0 and 2, terminals included.

5. Electrode according to one of the preceding claims, in which x is between 1 and 2, terminals inclusive.

6. Electrode according to one of the preceding claims, wherein said oxide crystallizes in the space group Pbcn.

7. Electrode according to one of the preceding claims, wherein said oxide has the following mesh parameters: - a = 8.69 A ± 0.10 A - b = 5.06 A ± 0.10 A and - c = 14.34 A ± 0.10 A.

8. Electrode according to one of the preceding claims, in which said oxide has a lamellar structure, a succession of sheets of NiOe and WOe octahedra, spaced apart by planes in which the lithium atoms are inserted, the distance between two closest tungsten atoms belonging to two successive sheets of octahedra being preferably greater than 3 A, or even greater than 4 A.

9. Anode subassembly (7) for electrochromic system (8), said anode subassembly (7) being adapted to be deposited above a substrate (1) with a glass function, comprising an electrode, in particular a counter electrode, as described according to one of the preceding claims.

10. Anode subassembly according to the preceding claim, comprising: - a transparent conductive layer (2B), - a counter-electrode (5) constituted by an electrode according to one of the preceding claims 1 to 7 and arranged above said first transparent conductive layer (2B).

11. Anode subassembly (7) according to the preceding claim, wherein said counter-electrode is in the form of a layer in contact with the transparent conductive layer.

12. Anode subassembly (7) according to claim 10, wherein said counter-electrode is in the form of a layer in contact with the transparent conductive layer, said layer being constituted by crystallized particles of said tungsten and nickel oxide dispersed in an organic or inorganic matrix.

13. Electrochromic system (8) incorporating a substrate (1) with a glass function, and comprising an electrode according to one of claims 1 to 8, in particular an anodic subassembly according to one of claims 9 to 12.

14. Electrochromic system (8) according to the preceding claim incorporating, from the surface of said substrate: - a cathode subassembly successively comprising a first transparent conductive layer (2A) and a working electrode (3); - an anode subassembly (7) as described according to one of claims 9 to 12, in particular successively comprising a counter-electrode (5) comprising said lithium, tungsten and nickel oxide according to one of claims 1 to 8, and a second transparent conductive layer (2B) arranged below said counter-electrode (5), - Lithium (Li) ions introduced into said electrochromic system (8).

15. Electrochromic system (8) according to claim 13 or 14, further comprising a separate layer (4) of an ionic conductor interposed between the electrode and the counter-electrode.

16. Electrochromic system (8) according to claim 13 to 15, wherein said working electrode comprises a tungsten oxide, in particular WO3, optionally doped with an element chosen from Ni, Nb, Mo, Ta, Ti, V, Zn, Zr, or a vanadium oxide, in particular V2O5.

17. Electrochromic system (8) according to one of claims 13 to 16, in which the thickness of the working electrode (3) is between 100 and 1500 nm.

18. Electrochromic system (8) according to one of claims 13 to 17, in which the thickness of the counter-electrode (5) is between 100 and 1500 nm.

19. Glazing incorporating an electrochromic system according to one of claims 13 to 18, said glazing being suitable for use as building glazing, in particular exterior glazing of an internal partition or glass door, or as glazing equipping internal partitions or windows of means of transport such as trains, planes, cars, boats.

20. Glazing according to the preceding claim, comprising at least two glass substrates, incorporating an electrochemical system according to one of claims 13 to 18]

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