HK1121284B - Device for storing electric power comprising a protective barrier layer for the collector - Google Patents

Description

The invention relates to the field of electrochemical devices for storing electrical energy.

This applies in particular to batteries and supercapacitors.

These devices are formed by the assembly of a plurality of electrochemical layers.

These devices usually consist of a multilayer unit assembly comprising electrode layers (cathode and anode) and separation layers interposed between the electrodes. The device may also include one or more collector layers, each collector layer being in contact with some electrode layers.

In the case of a liquid electrolyte device, the separation layer (separator) is formed of a porous material and the different layers are impregnated with a liquid electrolyte solution.

In the case of a solid electrolyte device, the separation layer shall consist of a solid electrolyte layer.

The function of the separation layer is to keep the electrode layers apart in order to avoid a short circuit of the electrochemical device while allowing an ion current to be established between the electrode layers through the electrolyte.

Each collector layer has the function of collecting and conducting current from an electrode attached to it.

In a lithium-polymer battery storage device, for example, the cathode layer (s) is (are) made up of a composition comprising a mixture of polymers and active charges. The polymer mixture typically contains a fluorine polymer, such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE).

The device consists of one or more collector layers associated with one or more cathode layers.The collector layer (s) is (are) formed of metal, such as aluminium or copper.

In a supercapacitor-type storage device, the electrode layer (s) is (are) composed of a composition comprising a mixture of polymers and active charges. The polymer mixture typically contains a fluorine polymer, such as polyvinylidene fluoride (PVDF) or polytetrafluoroethylene (PTFE).

The device consists of one or more collector layer (s) associated with one or more electrode layer (s).

The metal collector layer (s) naturally tend to form a surface oxide film on their surface, so that an aluminium collector layer forms an alumina (Al2O3) film on the surface.

When a collector layer is mechanically attached to a cathode layer, the oxide film at the interface between the collector layer and the cathode layer is broken.

During the operation of the electrochemical device, the ions of the electrolyte diffuse through the cathode to the collector. The ions of the electrolyte react with the metal of the collector to form a passivation layer. Thus, the oxide film is gradually replaced or supplemented by the passivation layer resulting from reactions between ions in the electrolyte and the metal of the collector.

In the case of an aluminium collector, in the presence of fluoride ions (F), the passivation layer typically contains aluminium fluoride (AlF3) or aluminium hydroxide (Al(OH) 3).

In the presence of lithium ions (Li+), a lithium oxide (Li2O) or lithium hydroxide (LiOH) layer is formed to replace the original oxide film.

Once formed, the passivation layer forms a barrier layer that prevents certain ions from the electrolyte from diffusing to the collector layer and thus protects the collector.

However, the formation of the passivation layer leads to a consumption of ions in the electrolyte and an attack of the collector layer.

In addition, in the case of a charged electrode, if the local break of the passivation layer occurs (e.g. due to shock, scratch or chemical dissolution), the presence of graphite charges within the electrode induces electrochemical reactions which dissolve the bare metal from the collector layer.

Finally, in the case of an aluminium collector layer and a polymer electrode layer, the presence of alumina on the surface of the collector layer causes poor adhesion of the electrode layer to the collector layer.

All these phenomena can lead to complete consumption of the collector layer during the life of the energy storage device and severely impair the functional characteristics of the device.

US 4 464 706 describes a lithium-ion battery, in which an electrically conductive layer of titanium or zirconium nitride is inserted between a current collector and the face of the electrode in contact with the current collector, to provide corrosion protection.

US 2004/0264110, US 6,565,701 and WO 03/094183 also describe structures in which an intermediate layer is arranged between a collector and an electrode.

One purpose of the invention is to preserve the collector layer during the lifetime of the electrochemical energy storage device.

This problem is solved in the present invention by means of an energy storage device as claimed 1. The stoichiometry x is defined as the ratio of the number of nitrogen atoms (N) to the number of metal atoms (Me) contained in the barrier layer.

The barrier layer protects the collector from the reactive species present in the electrolyte.

In addition, the barrier layer acts as an inhibitor of electrochemical reactions induced by the presence of graphite charges in the electrode layer.

The barrier layer may have the following advantageous characteristics: The barrier layer is formed by reactive magnetron spraying or reactive evaporation by plasma-activated electron gun,the barrier layer has a granular structure,the barrier layer is formed by arc-reactive evaporation or reactive evaporation by plasma-activated electron gun without plasma activation.

The invention also relates to a method of assembling an energy storage device as claimed 7.

The assembly process can advantageously include a preliminary step of selecting parameters: grain size of thickness and stoichiometry of the barrier layer according to a desired lifetime of the energy storage devices.

The process may also have the following advantageous characteristics: The process consists of a step to form the:barrier layer by deposition on a surface of the collector layer,the process consists of a step to form the barrier layer by deposition on a surface of the electrode layer,the process consists of a preliminary step to remove a surface of the collector layer intended to be in contact with the barrier layer,the process consists of a step to form the barrier layer by reactive magnetron spraying, reactive evaporation by plasma-activated electron gun, reactive evaporation by arcs or reactive evaporation by plasma-activated electron gun without plasma activation or any other process to obtain a barrier layer with the selected parameters.

Other features and advantages will be shown in the following description, which is purely illustrative and not limitative and should be read in conjunction with the figures annexed to this document, including: Figure 1 is a schematic representation of a multilayer unit assembly in an electrochemical energy storage device in accordance with a first embodiment of the invention,Figure 2 is a schematic representation of a multilayer unit assembly in an electrochemical energy storage device in accordance with a second embodiment of the invention,Figures 3 and 4 are schematic representations of barrier layer structures,Figure 5 is a schematic representation of a surface profile of the collector layer,Figures 6 to 14 are diagrams representing the parameters of a collector layer (stoichiometry, density, thickness) for different lifetimes of the liquid electrolyte energy storage device,Figure 15 is a diagram representing the parameters of a collector layer (stoichiometry, density, thickness) for different lifetimes of the solid electrolyte energy storage device,Figure 16 is a schematic representation of the steps of an assembly process of an electrochemical device according to an implementation of the invention,Figure 17 is a schematic diagram representing the barriers of the layer deployment as a function of the size of the barrier and the technical parameters of the barrier,Figure 18 is a diagram schematically representing a collector layer structure according to the deposition conditions.

In the first embodiment, an electrochemical energy storage device is formed by superimposing a plurality of multilayer unit sets conforming to the one shown in Figure 1.

The device can be obtained by winding the multilayer unit assembly or by stacking a plurality of multilayer unit assemblies, thus presenting a repetitive pattern defined by the unit assembly shown in Figure 1.

The multilayer unit assembly consists of a first collector layer 1, a first barrier layer 2, a first electrode layer 3, a first separation layer 4, a second electrode layer 5, a second barrier layer 6, a second collector layer 7, a third barrier layer 8, a third electrode layer 9, a second separation layer 10, a fourth electrode layer 11 and a fourth barrier layer 12.

The first collector layer 1 is associated with the first electrode layer 3 and a fourth electrode layer 11 of an adjacent unit set, i.e. the first collector layer 1 is in electrical contact with the first electrode layer 3 and the fourth electrode layer 11 of the adjacent set in order to collect the current from the first electrode layer 3 and the fourth electrode layer 11 of the adjacent set.

The first barrier layer 2 is interposed between the first collector layer 1 and the first electrode layer 3. The first barrier layer 2 is electrically conductive (i.e. the barrier layer 2 is capable of conducting electrons), so that the first collector layer 1 and the first electrode layer 3 are in electrical contact via the barrier layer 2.

The first separation layer 4 is a porous layer that extends between the two electrode layers 3 and 5. The separation layer 4 and the electrode layers 3 and 5 are impregnated with liquid electrolyte 13. The separation layer allows the first electrode layer 3 and the second electrode layer 5 to be kept at a distance from each other while allowing the circulation of ions from the electrolyte 13 between the two electrodes.

The second layer of collector 7 is connected to the second layer of electrode 5 and the third layer of electrode 5 respectively, i.e. the second layer of collector 7 is in electrical contact with the second and third layers of electrodes 5 and 9 in order to collect the current from the second and third layers of electrodes 5 and 9.

The second barrier layer 6 is interposed between the second collector layer 7 and the second electrode layer 5. The second barrier layer 6 is electrically conductive, so that the second collector layer 7 and the second electrode layer 5 are in electrical contact via the barrier layer 6.

The third barrier layer 8 is interposed between the second collector layer 7 and the third electrode layer 9. The third barrier layer 8 is electrically conductive, so that the second collector layer 7 and the third electrode layer 9 are in electrical contact via the barrier layer 8.

The second separation layer 10 is between the two layers of electrode 9 and 11. The separation layer 10 and the layers of electrodes 9 and 11 are impregnated with liquid electrolyte 13. The separation layer allows the third layer of electrode 9 and the fourth layer of electrode 11 to be kept at a distance from each other while allowing the circulation of ions from electrolyte 13 between the two electrodes.

The fourth barrier layer 12 is interposed between the fourth electrode layer 11 and a first collector layer 1 of an adjacent unit set (represented in dotted lines). The fourth barrier layer 12 is electrically conductive, so that the fourth electrode layer 11 and the first collector layer 1 are in electrical contact via the barrier layer 12.

Electrode layers 3, 5, 9 and 11 are composed of a mixture of polymers and active charges.

The collector layers 1 and 7 are formed of aluminium.

Liquid electrolyte 13 is an electrolyte with a viscosity of 0.5 to 1.5 centistoke (10-6 square metres per second) at 25 °C. Liquid electrolyte 13 consists of a composition of e.g. acetrylonite, γ-butyrolactone, propylene carbonate or a mixture of these compounds, or water, and a conductive salt, such as tetra-ethyl-ammonium-tetra-fluoroborate ((CH2H5) 4FNB4).

The barrier layers 2, 6, 8 and 12 are formed of titanium nitride (TiNx). Each barrier layer 2, 6, 8, 12 has a stoichiometry x ≥ 0.97 and a dense morphological structure, i.e. no intrinsic porosity. The stoichiometry of the barrier layers 2, 6, 8, 12 ensures that each barrier layer 2, 6, 8, 12 is neutral to aggressive reactive species (such as ${\mathrm{BF}}_4^{-},$ F-, OH-, H+, H2O , HCN) naturally present at the interfaces between collector layers 1 or 7 and associated electrode layers 3, 5, 9 and 11.

According to a second embodiment, an electrochemical energy storage device is formed by superimposing a plurality of multilayer unit sets conforming to that shown in Figure 2.

The device can be obtained by winding the multilayer unit assembly or by stacking a plurality of multilayer unit assemblies, thus presenting a repetitive pattern defined by the unit assembly shown in Figure 2.

The multilayer unit assembly comprises a stack of multiple layers, consisting of a collector layer 1, a first barrier layer 2, a first electrode layer 3 (cathode), a first solid electrolyte layer 14, a second electrode layer 15 (anode), a second solid electrolyte layer 16, a third electrode layer 11 (cathode), a second barrier layer 12 and a second barrier layer 12.

Each of the cathode layers 3 and 11 is associated with a collector layer.

The first electrode layer 3 is associated with the collector layer 1 and the third electrode layer 11 is associated with a collector layer 1 of an adjacent unit set (represented by dotted lines).

The first barrier layer 2 is interposed between the first collector layer 1 and the first electrode layer 3. The first barrier layer 2 is electrically conductive (i.e. the barrier layer 2 is capable of conducting electrons), so that the first collector layer 1 and the first electrode layer 3 are in electrical contact via the barrier layer 2.

The second barrier layer 12 is placed between the second electrode layer 11 and the collector layer 1 of the adjacent unit assembly. The second barrier layer 12 is electrically conductive, so that the second electrode layer 11 and the collector layer 1 are in electrical contact via the barrier layer 12.

It is noted that the anode layer 15 is not associated with a collector layer.

The electrolyte layers 14 and 16 are a solid electrolyte with a viscosity of 3-4 centistoke (10-6 square metres per second) at 25 °C. The solid electrolyte is composed of, for example, polyoxyethylene (POE) or polyethylene glycol (PEG) and a conductive salt such as lithium bis-trifluoro-methyl-sulfonyl-imide (LiTFSi).

Figures 3 and 4 show schematically the structures of protective layers deposited on a substrate.

In these figures, a protective layer 2 was applied to the surface of a substrate layer 1.

As can be seen from Figure 3, layer 2 is composed of grains with average dimensions substantially identical or greater than the grain dimensions of substrate layer 1.

In Figure 4, a layer 2 is formed of grains with average dimensions much smaller than the grain dimensions of substrate layer 1.

The total and continuous coating of the substrate surface requires that the average grain size of the protective layer be less than the surface roughness of the substrate layer.

If the grain size of layer 2 is of the order of the roughness of substrate layer 1 (Figure 3), a large part of the substrate surface will not be covered by layer 2. In addition, layer 2 will be mechanically brittle and more easily porous. In liquid electrolyte media (typically in the case of a supercapacitor), the interstices between the grains will be filled with electrolyte. In all cases, the protective layer 2 will not serve as a screw barrier to the substrate layer.

On the other hand, if the grain size of layer 2 is much less than the roughness of the substrate layer (Figure 4), the surface of the substrate layer will be completely covered by the protective layer 2.

Figure 5 shows a surface profile of the substrate layer

The profile line is formed by a succession of peaks and troughs.

The baseline is the middle line of the profile line.

The mean arithmetic deviation Ra is the arithmetic mean of the absolute values of the deviations between the peaks of peaks or troughs and the baseline.

The standard deviation Rq is the square mean of the deviations between the peaks or troughs and the baseline.

Apart from the classical roughness characteristics Ra and Rq, which inform the vertical component of surface roughness, two characteristic quantities of the horizontal component of surface roughness are defined:

The average distance between two successive ascending crossings of the baseline, marked Sm, is defined from a roughness profile. $S_m=\frac{1}{N}\sum _{i=1}^N{S}_i$

Sm, translates to the average width of the surface cavities or to an average grain size.

The mean square slope, denoted Δq, is the mean square of the slope of the roughness profile.

The mean square wavelength, denoted λq, is defined from the mean square roughness Rq and mean square slope Δq. ${\lambda }_q=2\pi \frac{R_q}{{\Delta }_q}$

λq is the periodicity of surface roughness.

Thus, as shown in Figure 4, barrier layer 2 preferably has an average grain size of about 40 times less than Sm or λq, which are parameters characterizing the horizontal component of the surface roughness of the substrate layer.

This condition being met, the barrier layer can be deposited on any substrate morphology (smooth, rough, striated, etched by chemical attack or by electron or ion bombardment, granular, etc.).

Examples 1 to 12

A variety of liquid electrolyte supercapacitors (viscosity ≤ 2 centistoke at 25 °C) are produced.

Each supercapacitor has a barrier layer of titanium nitride (TiNx) with a given mean grain size, thickness and stoichiometry.

A stoichiometry x is defined as the ratio of the number of nitrogen atoms (N) to the number of titanium atoms (Ti) contained in the barrier layer.

The resulting supercapacitor is measured for its lifetime.

For a supercapacitor, a service life n corresponds to a power supply for n hours at 70 degrees Celsius at a voltage between 2.3 and 2.8 volts.

The supercapacitor is considered to have reached its end of life when the supercapacitor has lost 20% of its initial capacity.

The results are given in Table 1, of which examples 1 to 5 and 8 to 10 are not part of the invention. - What? Tableau 1 - Durée de vie d'un supercondensateur à électrolyte liquide en fonction de paramètres de la couche barrière (taille de grains, épaisseur, stoechiométrie)

	Taille de grain (nm)	Epaisseur (µm)
Exemple 1	40 ± 5	0,23	0,80	125
Exemple 2	40 ± 5	0,25	0,95	300
Exemple 3	40 ± 5	0,35	0,95	600
Exemple 4	30±5	0,21	0,77	200
Exemple 5	30 ±5	0,08	0,95	300
Exemple 6	30±5	0,20	0,99	1000
Exemple 7	30±5	0,30	0,85	1000
Exemple 8	30±5	0,39	0,96	3000
Exemple 9	20±5	0,08	0,97	600
Exemple 10	20±5	0,16	0,83	900
Exemple 11	20±5	0,15	0,95	1200
Exemple 12	20±5	0,23	0,99	2100

Figures 6 to 14 are diagrams showing the parameters of a barrier layer (stoichiometry, density, thickness) for different supercapacitor lifetimes.

The diagrams in Figures 6 to 8 have been drawn for a grain size of 40 ± 5 nanometres.

In Figure 6 the grey area represents a service life of more than 500 years.

In the diagram in Figure 7, the grey area corresponds to a service life of more than 1000.

In the diagram in Figure 8, the grey area corresponds to a service life of more than 2000 years.

Figures 9 to 11 have been drawn for a grain size of 30 ± 5 nanometres.

In Figure 9, the grey area represents a service life of more than 500 years.

In the diagram in Figure 10, the grey area corresponds to a service life of more than 1000.

In the diagram in Figure 11, the grey area corresponds to a service life of more than 2000 years.

Figures 12 to 14 have been drawn for a grain size of 20 ± 5 nanometres.

In Figure 12 the grey area represents a service life of more than 500 years.

In the diagram in Figure 13, the grey area corresponds to a service life of more than 1000.

In the diagram in Figure 14, the grey area corresponds to a service life of more than 2000 years.

Examples 13 to 24

A variety of lithium-polymer solid electrolyte batteries are being produced (viscosity > 2 centistoke at 25 degrees Celsius).

Each battery contains a barrier layer of titanium nitride (TiNx) with a given mean grain size, thickness and stoichiometry.

A stoichiometry x is defined as the ratio of the number of nitrogen atoms (N) to the number of titanium atoms (Ti) contained in the barrier layer.

The battery life is measured.

For a battery, a lifetime n corresponds to n charge and discharge cycles between 2 and 3,3 volts at 90 degrees Celsius (battery operating temperature), with a charge phase of 4 hours and a discharge phase of 2 hours.

The battery is considered to have reached its end of life when the battery has lost 20% of its original capacity.

The results are given in Table 2, of which examples 13 to 17 and 20 to 22 are not part of the invention. - What? Tableau 2 - Durée de vie d'une batterie à électrolyte solide en fonction de paramètres de la couche barrière (taille de grains, épaisseur, stoechiométrie)

	Taille de grain (nm)	Epaisseur (µm)
Exemple 13	40±5	0,23	0,80	1100
Exemple 14	40±5	0,25	0,95	1200
Exemple 15	40±5	0,35	0,95	1350
Exemple 16	30±5	0,21	0,77	950
Exemple 17	30±5	0,08	0,95	400
Exemple 18	30±5	0,20	0,99	1200
Exemple 19	30±5	0,30	0,85	1100
Exemple 20	30±5	0,39	0,96	1300
Exemple 21	20±5	0,08	0,97	550
Exemple 22	20±5	0,16	0,83	1050
Exemple 23	20±5	0,15	0,95	1100
Exemple 24	20±5	0,23	0,99	1200

Figure 15 is a diagram representing the parameters of a barrier layer (stoichiometry, density, thickness) for different battery lifetimes. This diagram was drawn for grain sizes of 20 ± 5 nm, 30 ± 5 nm and 40 ± 5 nm. Examples 13 to 24 are shown on this diagram.

In this diagram, the area shown in black corresponds to a lifetime of 1000 or more.

It should be noted that in the case of a solid electrolyte energy storage device, the average grain size of the barrier layer has little influence on the lifetime of the energy storage device.

Figure 16 shows in a schematic manner the steps of a process for assembling an electrochemical device conforming to an implementation of the invention.

In a first step 100, a surface of the collector layer 1 is stripped. This stripping step involves removing a superficial film of oxides and surface deposits (greases, hydrocarbons, etc.) present on the surface of the collector layer 1.

The first step of the process is for example by plasma ion bombardment or treatment. The gas used is argon (and may contain dihydrogen H2 or ammonia NH3). The working pressure is between 10-1 and 10-3 millibar. The power of the plasma generator is between 1 and 10 kilowatts and the treatment time is about 10 to 30 seconds.

In a second step, parameters (grain size, thickness, stoichiometry) of a barrier layer are selected according to the desired lifetime.

In this step, reference is made to the diagrams in Figures 6 to 14 or to the diagram in Figure 15.

In a third step 300, a barrier layer 2 with controlled grain size, thickness and stoichiometry is applied to the surface stripped from the collector layer 1.

The deposition is carried out at a working pressure of 10-2 to 10-4 millibars, with an electron cannon power of 25 to 75 kilowatts, the substrate (collector) being maintained at a temperature below 100 degrees Celsius, with a gas flow (N2 nitrogen) of 10 to 104 cm3 (standard cubic centimeters per minute).

Another possibility is that this third stage is carried out by an arc evaporation deposition technique. The deposition is carried out at a working pressure of 10-2 to 10-4 millibars, with an arc generator power of 25 to 75 kilowatts, the substrate (collector) being maintained at a temperature below 100 degrees Celsius, with a gas flow (N2 nitrogen) of 10 to 104 cm3 (standard cubic centimeters per minute).

Another possibility is that this third step is carried out by a reactive magnetron spray deposition technique, where the deposition is carried out at a working pressure of 10-2 to 10-4 millibars, with a reactive magnetron generator power of 5 to 30 kilowatts, the substrate (collector) being kept at a temperature below 100 degrees Celsius, with a gas flow (N2 nitrogen) of 10 to 104 cm3 (standard cubic centimetres per minute).

In a fourth step 400, an electrode layer 3 and the associated collector layer 1 are assembled so that the barrier layer 2 extends between electrode layer 3 and collector layer 1.

In the assembly process just described, a barrier layer is laid on a surface of a collector layer.

In the case of a solid electrolyte energy storage device, the barrier layer could be deposited on an electrode layer.

In this case, at step 300, the barrier layer 2 with controlled grain size, thickness and stoichiometry can be deposited on a surface of electrode layer 3.

The deposition is carried out at a working pressure of 10-2 to 10-4 millibars, at a power of 0.5 to 5 kilowatts, the substrate (electrode) being maintained at a temperature below 25 degrees Celsius, with a gas flow (N2 nitrogen) of 1 to 103 cm3 (standard cubic centimetres per minute).

Figure 17 is a diagram schematically representing the techniques of depositing the barrier layer according to stoichiometric parameters and barrier layer grain size.

The electron gun reactive evaporation deposition techniques (domain A) are suitable for obtaining a stoichiometry x between 0,7 and 0,8 and a grain size between 40 and 50 nanometres.

Arc-reactive evaporation deposition techniques (domain B) are suitable for obtaining stoichiometry x between 0.9 and 1 and grain size between 30 and 40 nanometres.

Plasma-assisted electron cannon reactive evaporation deposition techniques (C-domain) are suitable for obtaining x stoichiometry between 0.8 and 1 and grain size between 20 and 30 nanometres.

The deposition techniques by reactive magnetron spray (domain D) are suitable for obtaining a stoichiometry x between 0.95 and 1.05 and a grain size between 10 and 20 nanometres.

For a lifetime of a liquid electrolyte energy storage device in standard application of the continuous-feed type (lifetime n = 1000), the energy storage device shall include a barrier layer whose parameters are defined by field E. Field E corresponds to a stoichiometry between 0,85 and 1,05 and a grain size between 10 and 30 nanometres.

For a standard electric vehicle-type solid electrolyte energy storage device lifetime (lifetime n = 1000), the energy storage device shall comprise a barrier layer whose parameters are defined by domain F. Domain E corresponds to a stoichiometry between 0,75 and 1,05 and a grain size between 10 and 40 nanometres.

Figure 18 is a diagram schematically representing a barrier layer structure according to the deposition conditions.

The diagram includes a first zone (Zone 1) in which the structure of the deposited material is porous granular, a second zone (Zone 2) in which the structure of the deposited material is columnar and a third zone (Zone 3) in which the structure of the deposited material is crystalline.

The deposit morphology offering the highest density is obtained by crystalline growth (Zone 3). However, such growth is not possible because the substrate (collector or electrode) is polycrystalline and rough.

If not, the most suitable deposition morphology to meet the density requirement is obtained by column growth (Zone 2). This type of growth is observed in the case of deposition by reactive magnetron spraying and in some configurations of deposition by reactive evaporation by plasma-activated electron gun.

A deposit morphology that can also meet the density requirement is obtained by granular growth (Zone 1). This type of growth is observed in the case of either arc-reactive evaporation or plasma-free electron cannon-reactive evaporation deposition. However, the resulting layers are naturally porous and the density requirement is only attainable if the grain size is very small (apparent diameter less than 20 nanometers measured in atomic force microscopy for example), which requires working at very low pressures (< 10 milliTorr) difficult to achieve the nitration reaction, and then requires the presence of a flow of diazote (N2).

A dense deposit morphology can only be obtained if the oxides and hydroxides on the surface of the substrate (e.g. alumina and aluminium hydroxide for an aluminium-based collector, copper oxides CuOx for a copper-based collector) are removed before the deposit itself.

Claims (12)

1. A power storage device including an electrode layer (3, 5, 9, 11) and a collector layer (1, 7) associated with the electrode layer, also including a barrier layer (2, 6, 8, 12) formed from a metallic nitride MeN_x wherein Me is one or more metals, the barrier layer (2, 6, 8, 12) being inserted between the electrode layer (3, 5, 9, 11) and the collector layer (1, 7), the barrier layer (2, 6, 8, 12) being adapted to prevent diffusion of ions contained in an electrolyte (13, 14, 16) up to the collector layer (1, 7), characterized in that the barrier layer (2, 6, 8, 12) has a stoichiometry value x comprised between 0.85 and 1.05, a grain size comprised between 10 and 30 nanometers and a thickness comprised between 0.15 and 0.30 micrometers.
2. The device according to claim 1, wherein the barrier layer (2, 6, 8, 12) is formed from titanium nitride (TiN), chromium nitride (CrN) or titanium nitride-aluminium (TiAlN).
3. The device according to one of claims 1 or 2, wherein the barrier layer (2, 6, 8, 12) exhibits a columnar structure.
4. The device according to claim 3, wherein the barrier layer (2, 6, 8, 12) is formed by reactive magnetron sputtering or by reactive evaporation by plasma-activated electron gun.
5. The device according to one of claims 1 or 2, wherein the barrier layer (2, 6, 8, 12) has a granular structure.
6. The device according to any of claim 5, wherein the barrier layer is formed by reactive arc evaporation or by reactive electron-gun evaporation without plasma activation.
7. A method for a power storage device assembly including an electrode layer (3, 5, 9, 11) and a collector layer (1, 7) associated with the electrode layer (3, 5, 9, 11), including a step (400) that consists of inserting, between the electrode layer (3, 5, 9, 11) and the collector layer (1, 7), a barrier layer (2, 6, 8, 12) formed from a metallic nitride MeN_X, wherein Me is a one metal or more metals,the barrier layer (2, 6, 8, 12) being adapted to prevent diffusion of ions contained in an electrolyte (13, 14, 16) up to the collector layer (1, 7), characterized in that the barrier layer (2, 6, 8, 12) has a stoichiometry value x comprised between 0.85 and 1.05, a grain size comprised between 10 and 30 nanometers and a thickness comprised between 0.15 and 0.30 micrometers.
8. The method according to claim 7, including a step (200) that consists of selecting grain-size, thickness and stoichiometry parameters of the barrier layer (2, 6, 8, 12) in accordance with a lifetime sought for the power storage device.
9. The method according to one of claims 7 or 8, including a step (300) that consists of forming the barrier layer (2, 6, 8, 12) by deposition onto a surface of the collector layer (1, 7).
10. The method according to one of claims 7 or 8, including a step (300) that consists of forming the barrier layer (2, 6, 8, 12) by deposition onto a surface of the electrode layer (3, 5, 9, 11).
11. The method according to one of claims 7 through 10, including a preliminary step (100) that consists of scouring a surface of the collector layer (1, 7) intended to be in contact with the barrier layer (2, 6, 8, 12).
12. The method according to one of claims 7 through 11, including a step (300) that consists of forming the barrier layer (2, 6, 8, 12) by reactive magnetron sputtering, by reactive evaporation by plasma-activated electron gun, by reactive arc evaporation or byreactive electron-gun evaporation without plasma activation.