EP-4740064-A1 - DEVICE AND METHOD FOR REVERSIBLE ELECTRODEPOSITION OF A ZINC FILM ON AN ELECTRODE WITH A TRANSPARENT SEMI-CONDUCTIVE OR CONDUCTIVE SURFACE AND ELECTROCHROMIC GLAZING OBTAINED

EP4740064A1EP 4740064 A1EP4740064 A1EP 4740064A1EP-4740064-A1

Abstract

An electrochromic device (1, 11) comprising: - a device for reversible electrodeposition of a zinc film Zn at the negative electrode, the device comprising a negative electrode, a positive electrode, a volume containing an electrolyte (4, 14) with Zn 2+ ions, the negative electrode having a transparent semi-conductive or conductive surface comprising a conductive or semi-conductive material which is a transparent metal oxide, the electrolyte being aqueous or in gel form, the electrolyte containing ethylene glycol, polyethylene glycol or derivatives of these compounds, the pH of the electrolyte being between 4 and 7, - a means for applying a current imposed between the negative electrode and the positive electrode, in order to pass, at each galvanostatic step of the cycle, from a transparent state to a coloured or even opaque state of the device, the device for reversible electrodeposition of the zinc film Zn making it possible to pass during each cycle, at a second step that follows the galvanostatic step, from the coloured or even opaque state from the galvanostatic step to a transparent state of the entire transparent semi-conductive or conductive surface.

Inventors

BALLAND, Véronique
LIMOGES, Benoît
PALAMADATHIL KANNATTIL, Hamid

Assignees

Université Paris Cité
Centre National de la Recherche Scientifique

Dates

Publication Date: 20260513
Application Date: 20240424

Claims (20)

1. Electrochromic device (1, 11), such as an electrochromic window comprising: - a device for reversible electrodeposition of a zinc Zn film at the negative electrode, to produce an electrochromic electrode at the negative electrode, the device comprising a negative electrode, a positive electrode, a volume arranged between the negative electrode and the positive electrode and containing an electrolyte (4, 14) with Zn 2+ ions, the negative electrode has a transparent semiconducting or conducting surface, the transparent semiconducting or conducting surface of the negative electrode comprising a conducting or semiconducting material which is a transparent metal oxide, the electrolyte (4, 14) being aqueous or in the form of a gel, the electrolyte (4, 14) containing ethylene glycol, polyethylene glycol or derivatives of these compounds, the pH of the electrolyte (4, 14) being between 4 and 7, - a means for applying a current which is imposed between the negative electrode and the positive electrode, in order to control the electrical intensity injected into the circuit, this current making it possible to pass at each galvanostatic step of the cycle, from a transparent state to a colored state of the device, by homogeneous electro-deposition of the zinc film on the entire transparent semi-conductor or conductive surface of the negative electrode, the device for reversible electro-deposition of the zinc Zn film making it possible to pass during each cycle, at a second step which follows the galvanostatic step, from the colored state of the galvanostatic step to a transparent state of the entire transparent semi-conductor or conductive surface by electro-dissolution of the zinc film in the electrolyte (4, 14), and in which the negative electrode is without pre-functionalization or chemical modification of its transparent semi-conductor or conductive surface in order to promote the nucleation and homogeneous growth of the deposition of the zinc film during electrodeposition on its transparent semiconducting or conductive surface.
2. Electrochromic device according to claim 1, characterized in that the electrolyte is without the addition of additives which are metal ions to promote the pre-nucleation of the zinc film during electrodeposition on the transparent semi-conductor or conductive surface on the negative electrode.
3. Electrochromic device according to one of claims 1 to 2, characterized in that: - the negative electrode is without pre-functionalization or chemical modification of its transparent semi-conductor or conductive surface, by metallic particles such as nanoparticles of platinum, silver, copper, bismuth, and - the electrolyte being without the addition of other metal ions, and in particular without the addition of other metal ions such as bismuth 2+ or copper 2+ ions intended for pre-nucleation of the zinc film during electrodeposition on the transparent semi-conductor or conductive surface on the negative electrode.
4. Electrochromic device according to one of claims 1 to 3, characterized in that the transparent conductive or semi-conductive material of the negative electrode comprises a tin-doped indium oxide (or ITO) and the electrolyte (4, 14) is without buffer.
5. Electrochromic device according to one of claims 1 to 4, characterized in that the transparent conductive or semi-conductive material of the negative electrode comprises a fluorine-doped tin dioxide (or FTO) and the electrolyte (4, 14) is buffered.
6. Electrochromic device according to any one of claims 1 to 5, characterized in that the device (11) is said to be asymmetrical, and the positive electrode is an electrochromic electrode with a transparent semi-conductive or conductive surface, the means of applying an electric current imposed at each galvanostatic step of the cycle, between the negative electrode and the electrode positive, to pass from a discharged configuration to a charged configuration, allowing to pass: to the transparent semiconducting or conducting surface of the negative electrode from a transparent state to a colored state, and to the transparent semiconducting or conducting surface of the positive electrode from a transparent state to a colored state, the passage from a charged configuration to a discharged configuration by circulation in a discharge circuit of a current from the positive electrode to the negative electrode, allowing to pass during the second step of each cycle: for the transparent semiconducting or conducting surface of the negative electrode from a colored state to a transparent state; and for the transparent semiconducting or conducting surface of the positive electrode from a colored state to a transparent state.
7. Electrochromic device according to claim 6, characterized in that the imposed current has values between 0.1 and 10 mA/ cm2 and in that the potential measured following the passage of the imposed current between the two electrodes is between +1 and +2 V for asymmetric devices.
8. Electrochromic device according to one of claims 6 to 7, characterized in that the device comprises a sacrificial zinc electrode, which makes it possible to regenerate the initial transparency of the device after cycling via electrical coupling to the negative or positive electrode, for example in the event of accumulation of a color at one of the two transparent electrodes.
9. Electrochromic device (11) according to any one of claims 6 to 8, characterized in that the asymmetric device has materials chosen at the positive electrode and at the negative electrode to deliver electrical energy in the discharge circuit, with a voltage greater than 0.5 V, advantageously greater than 1 V, the device being qualified in this case as an electrochromic battery.
10. Electrochromic device (1, 11) according to any one of claims 6 to 8, characterized in that the electrolyte contains a reagent capable of electrodepositing on the surface of the positive electrode and which allows it to pass from a transparent state to a colored state.
1 1 . Electrochromic device (1 , 1 1 ) according to claim 9 or 10, characterized in that the positive electrode has on its transparent surface an electrochromic material which makes it possible to pass from a transparent state to a colored state, by disinsertion of ions.
12. Electrochromic device (1, 11) according to any one of claims 6 to 11, characterized in that the electrolyte contains a reagent or several reagents capable of electroprecipitating on the transparent semiconducting or conducting surface of the positive electrode and which allows it to pass from a transparent state to a colored state.
13. Electrochromic device (1, 11) according to any one of claims 1 to 12, characterized in that the transparent semiconducting or conducting surface of the negative electrode is nano-structured by a thin film deposited on the surface.
14. Electrochromic device (1, 11) according to any one of claims 1 to 12, characterized in that the surface of the positive electrode is nano-structured by a thin film deposited on the surface.
15. Electrochromic device (1, 11) according to claim 13 or 14, characterized in that the nano-structured thin film is a semiconducting or conducting metal oxide, such as: ITO, FTO, TiOs, SnOs.
16. Electrochromic device (1, 11) according to any one of claims 6 to 15, characterized in that the electrolyte comprises Mn 2+ ions and the positive electrode involves the Mn 2+ /MnC>2 pair during charging and discharging, the MnC>2 being deposited by electrodeposition on its transparent surface, for example based on ITO, during charging.
1 7. Electrochromic device (1, 11) according to any one of claims 6 to 1 5, characterized in that the positive electrode is covered on its transparent surface when discharging with Prussian white and when charging with Prussian blue.
18. Electrochromic device (1, 11) according to any one of claims 6 to 15, characterized in that the electrolyte contains Br- ions and a quaternary amine.
19. Electrochromic device (1) according to any one of claims 1 to 5, characterized in that the device is said to be symmetrical and the positive electrode is a grid comprising zinc opposite the negative electrode.
20. Electrochromic device according to claim 19, characterized in that the imposed current has values between ±0.1 and ±10 mA/cm 2 and in that the potential measured between the two electrodes following the passage of the imposed current is between -0.3 and 0.3 V for symmetrical devices.

Description

Device and method for reversible electrodeposition of a zinc film on an electrode with a transparent semiconducting or conductive surface and electrochromic glazing obtained Technical field The invention relates to methods and devices for reversible electrodeposition of a zinc film on an electrode with a transparent semi-conductive or conductive surface, for the manufacture of glazing. State of the art In state-of-the-art systems, a device can be proposed comprising a single electrode exhibiting electrochromic properties, with a counter electrode which is a grid or a zinc plate and which is not used for electrochromism. The energy efficiency of buildings is a lever for the energy transition, essential in sustainable development strategies and the fight against global warming. A relevant way to increase the comfort and energy efficiency of buildings is to use smart windows. A window here refers to a bay with a glass enclosure that allows lighting of a room, for example a residential or commercial space. A smart window here refers to a window whose optical properties of the glazing can be adapted to requirements. The glazing is called smart glazing, switchable glazing or dynamic glazing. By regulating both light and heat transfer, smart windows improve the energy efficiency of a building's heating, ventilation and air conditioning (HVAC) system. Replacing static low-E windows with such smart windows would deliver energy savings of 20% on average, and up to 45%, significantly reducing carbon emissions associated with the built environment. Smart windows can be classified into different categories, depending on the parameter modulating the optical properties of the glazing, or depending on the materials used for the glazing. In liquid crystal windows and windows with suspended particle devices (SPD) in the glazing, the optical properties of the glazing are modified by applying an electric field. In windows with chromic material, the optical properties of the glazing are modified depending on the light intensity (photochromic glazing), heat (thermochromic glazing), the injection of a gas (gasochromic glazing), or the electrical voltage (electrochromic glazing). The invention relates more particularly to smart windows with electrochromic glazing. The electrochromic glazings currently on the market use electrochromism, which is a change in the optical properties of a material when an electrical potential difference is applied, an inversion of the polarization allowing it to return to the initial state, in a reversible manner. The principle of electrochromism is conventionally illustrated using a device comprising five layers, namely two layers of transparent and conductive oxides (Transparent Conducting Oxides TCO), two layers of electrochromic material forming a working electrode and a counter-electrode, and an electrolyte placed between the two electrodes. When a voltage is applied, electrons migrate through the TCOs and ions pass through the electrolyte to insert themselves into one of the electrochromic materials. This transfer of ions (e.g. H + , Li + , Na + ) and electrons causes redox reactions of the transition metals of the electrochromic layers, which leads to a color change. For example, thin layers of tungsten oxide WO3 switch from a transparent state to blue, by insertion of lithium ions Li + , sodium ions Na + or protons. The combination of WO3 and nickel oxide NiO x makes it possible to obtain neutral, grey-coloured glazing. Performance indicators for electrochromic devices are optical contrast, optical efficiency, memory effect, switching or response time, cycling life or durability, operating temperature range, and applied potential range. Optical contrast is the ratio of optical reflection or transmission between the colored state and the transparent state, often calculated for the wavelength corresponding to the maximum sensitivity of the human eye (550 nm). Memory effect is the time during which the electrochromic device retains its coloration, after stopping the application of a potential difference. The switching time is the time required for the material to change from a coloration to a discoloration, a time of about ten minutes being accepted for smart windows of approximately one square meter. The electrolyte can be liquid, solid (for example metal oxide such as Ta 2 O 5 ), or in the form of a polymer membrane. Electrochromic materials can be organic or inorganic. Organic electrochromic materials are either conductive polymers (polyaniline PAN I , polypyrrole PPy, polythiophene PTh and their derivatives such as for example poly(3,4-(ethylenedioxy)thiophene) PEDOT), or materials based on viologens, or materials based on Prussian blue. Inorganic electrochromic materials can be cathodically colored (e.g. WO3 , Nb2O5 , M0O3, lnO2 :Sn, V2O5 , TiO2 ), or anodically colored (e.g. lrOx , LixCo02 , MnO2 , C03O4, NiO ). A state of the art of inorganic electrochromic materials is presented by Granq