A solid-state battery cell, a method of manufacturing such a solid-state battery cell, and a solid-state battery-enabled system comprising such a solid-state battery cell

Abstract

A solid-state battery cell, a solid-state battery-enabled system including a solid-state battery cell, and a method of manufacturing such a solid-state battery cell, wherein the solid-state battery cell has an anode, formed using an anode material, a cathode, formed using a cathode material, a solid electrolyte arranged between the anode and the cathode, formed using an electrolyte material, a first interface material arranged between the anode and the solid electrolyte having first interface material side facing the anode and a second interface material side facing the solid electrolyte, and a second interface material arranged between the solid electrolyte and the cathode having first interface material side facing the solid electrolyte and a second interface material side facing the cathode.

Description

A SOLID-STATE BATTERY CELL, A METHOD OF MANUFACTURING SUCH A SOLID-STATE BATTERY CELL, AND A SOLID-STATE BATTERY- ENABLED SYSTEM COMPRISING SUCH A SOLID-STATE BATTERY CELLFIELD OF THE INVENTION

[0001] The present invention relates to a solid-state battery cell where all components of the battery, the cathode, electrolyte and anode, are solids, with interfaces between each component, and a method which allows for the fabrication of such a battery and a solid-state battery-enabled system comprising the above-mentioned solid-state battery.BACKGROUND

[0002] The concept of a rechargeable battery requires that ions are able to reside on both sides of an electrolyte placed in-between an anode and a cathode. This electrolyte needs to allow for the ions to pass through it but remain electrically insulating. On one side (the cathode), as part of a stable phase whose chemical stability ultimately provides the energy of the battery and metastable on the other (the anode), as a result of charging or applied voltage. The applied recharging voltage drives the ions into a storage, e.g. a network of atoms, or in between atomic planes in a crystalline phase, waiting for the circuit to be closed allowing them to pass through the electrolyte again recombining with the stable phase they belonged to.

[0003] The most pressing issues that current battery designs face relate to the interfaces between these three main constituents of the battery, as well as the fact that the electrolyte is a liquid, commonly a flammable carcinogen, which can cause fires, if the battery is damaged. As an example of both issues, one of the most commonly referred to problem is the formation of metal dendrites from the working ions. During discharge the ions travel through the electrolyte and accumulate at a few discreet sites on the surface of the cathode . At these sites, they build up and form so-called dendrites that extend into the liquid electrolyte and possibly all the way to the anode causing a short and destroying the battery.

[0004] With the discovery of fast ion transport in a solid, it became possible to solve this issue by creating an electrolyte that the metal dendrites could not penetrate, whileat the same time removing the dangerous flammable electrolyte. This marked the advent of solid-state batteries having a solid-state electrolyte, sparking a new field within battery research which has grown fast in the past decades.

[0005] A key challenge in the field of solid-state batteries is achieving interfacial compatibility between the solid electrolyte and both the anode and cathode, while also ensuring sufficient ion conductivity. For instance, in LiPON solid electrolytes, lithium-ion transport is often hindered at the interfaces. Additionally, the high elastic modulus and hardness of LiPON act as barriers against the growth of lithium dendrites. Unlike liquid electrolytes, where conductivity is determined by the choice of solvents, the conductivity in solid-state electrolytes depends on their structural framework.SUMMARY OF THE INVENTION

[0006] It is the object of the present invention to improve ionic conductivity at the interface between the anode / cathode and the solid electrolyte by addressing and eliminating the interfacial challenges commonly encountered in solid-state batteries, as described above.

[0007] In the first aspect of the invention, a solid-state battery cell is provided, comprising: an anode, formed using an anode material, a cathode, formed using a cathode material, a solid electrolyte arranged between the anode and the cathode, formed using an electrolyte material, a first interface material arranged between the anode and the solid electrolyte, having a first interface material side facing the anode and a second interface material side facing the solid electrolyte, a second interface material arranged between the solid electrolyte and the cathode, having a first interface material side facing the solid electrolyte and a second interface material side facing the cathode, wherein the first interface material side of the first interface material has an atomic composition essentially containing anode material and the second interface material side of the first interface material has an atomic composition essentiallycontaining electrolyte material, where the material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material, wherein the first interface material side of the second interface material has an atomic composition essentially containing electrolyte material and the second interface material side of the second interface material has an atomic composition essential containing cathode material, where the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material.

[0008] Accordingly, the first interface material may be seen as an interface region made of an interface material whose atomic composition is not fixed but changes from that of the anode material to that of the solid electrolyte material. Similarly, the second interface material may be seen as an interface region made of an interface material whose atomic composition is not fixed but changes from that of the solid electrolyte material to that of the cathode material. In that way, it is ensured that there are no abrupt changes in chemical composition between any or all of the anode, electrolyte, and cathode.

[0009] In an embodiment, the first and the second interface materials comprise a single-crystalline, polycrystalline or amorphous atomic arrangement, and where the atoms constituting to the first and the second interface materials form a chemical compound of varying atomic composition.

[0010] A chemical compound, as described in the present invention, refers to a pure substance formed through the chemical bonding of two or more different elements in a specific ratio. These bonds, such as ionic or covalent bonds, hold the constituent elements together, and breaking them into individual elements requires a chemical reaction. In contrast, mixtures and composite materials differ significantly: a mixture consists of two or more substances (elements or compounds) that are physically combined but not chemically bonded, allowing each to retain its own properties. Composites, on the other hand, are materials formed by combining distinct substances without chemical reaction, resulting in heterogeneous structures where each substance retains its physical and chemical characteristics.

[0011] The use of a chemical compound for interface materials offers a critical advantage over mixtures or composites. Mixtures and composites introduce additional boundaries between the constituent substances, exacerbating interface-related issues between the anode and electrolyte, as well as the electrolyte and cathode. An ion traversing a mixture or composite interface material encounters numerous additional boundaries, which increases resistance and hinders performance. In contrast, a chemical compound, being homogeneous at the molecular level, eliminates these additional boundaries.

[0012] This invention employs manufacturing methods such as Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD) to ensure that the interface material is a chemical compound, thereby avoiding the drawbacks associated with mixtures or composites.

[0013] In an alternative embodiment, the continuous gradient in the atomic composition for the first and the second interface materials includes linearly varying atomic composition or non-linearly varying atomic composition. The first interface material comprises in one embodiment a stepped gradient chemical compound comprising a plurality of layers, where the continuous gradient in the atomic composition from the composition of the anode material to the atomic composition of the electrolyte material is generated by a different percentage of the anode material and the electrolyte material in each layer. Similarly, the second interface material comprises in one embodiment a stepped gradient chemical compound comprising a plurality of layers, where the continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material is generated by a different percentage of the electrolyte material and the cathode material in each layer.

[0014] In a preferred embodiment, the first and / or the second interface material has a gradient in atomic composition in the direction perpendicular to the interface material sides, and where the composition in the directions parallel to the interface material sides is uniform.

[0015] The anode, solid-state electrolyte and the cathode are arranged on any type of a suitable substrate.

[0016] Accordingly, a solid-state battery is provided that eliminates completely sharp interfaces and create instead a new layer which binds the two adjacent materials, i.e. between the anode and solid-state electrolyte, and between the solid-state electrolyte and the cathode, respectively, such that ions traveling between them never see a drastic / abrupt difference in their chemical environment but rather move gradually from one to the other. This means that all the degradation mechanisms which are associated with the interfaces are no longer present.

[0017] In a second aspect of the invention, a solid-state battery-enabled system is provided comprising the above-mentioned solid-state battery. This may as an example include any type of battery driven vehicle, bicycle, device and a system.

[0018] In a third aspect of the invention, a method is provided for manufacturing a solid-state battery onto a substrate, where the solid-state battery comprises an anode, a cathode, and a solid electrolyte arranged between the anode and the cathode material, comprising: producing a first interface material between the anode and the solid electrolyte having a first interface material side facing the anode and a second interface material side facing the solid electrolyte, where the step of producing comprises: depositing an anode material and an electrolyte material in a controlled way such that the first interface material side of the first interface material has an atomic composition essentially containing anode material and the second interface material side of the first interface material has an atomic composition essentially containing electrolyte material, and where the controlling is such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material, producing a second interface material between the solid electrolyte and the cathode having a first interface material side facing the solid electrolyte and a second interface material side facing the cathode, where the step of producing comprises: depositing an electrolyte material and a cathode material in a controlled way such that the first interface material side of the second interface material hasan atomic composition essentially containing electrolyte material and the second interface material side of the second interface material has an atomic composition essentially containing cathode material, and where the controlling is such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material.

[0019] The step of depositing the anode material and the electrolyte material, and the electrolyte material and the cathode material, may in an embodiment comprise using chemical vapour deposition or physical vapour deposition.

[0020] Also, in an embodiment, the step of depositing the anode material and the electrolyte material in a controlled way comprises adjusting the atomic or molecular flux of the anode material and the electrolyte material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a pre-defined time interval.

[0021] Similarly, in an alternative embodiment, the step of depositing the electrolyte material and the cathode material in a controlled way comprises adjusting the atomic or molecular flux of the electrolyte material and the cathode material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a predefined time interval.

[0022] In an embodiment, the above-mentioned controlling comprises adjusting the atomic or molecular flux by one or more of the following methods: adjusting the power applied to a physical vapour deposition source over a time interval, or adjusting the pressure or flow of a precursor gas over a time interval, or adjusting the substrate temperature of a substrate on which the solid-state battery is built or the substrate potential over a time interval.

[0023] The anode may be produced from an anode material, or the cathode from a cathode material, or the solid electrolyte from an electrolyte, but this may as an example be manufactured In-Situ with a well know technique, e.g., sputtering technique just to mention an example.

[0024] Accordingly, a method is provided for producing a solid-state battery that eliminates sharp interfaces entirely by forming a new intermediate layer that seamlessly connects the adjacent materials — specifically between the anode and the solid-state electrolyte, as well as between the solid-state electrolyte and the cathode. This design ensures that ions traveling between these materials experience a smooth and gradual transition in their chemical environment, rather than encountering abrupt changes. As a result, all degradation mechanisms typically associated with interfacial issues are effectively eliminated.

[0025] The first and the second interface between the different components of the solid-state battery may “move” or “expand / contracf ’ depending on the state of the charge of the battery across the interfaces since they are integrated. There just needs to be a driving force from one end of the solid-state battery to the other and that during charging there is capacity to store the ions there at a minimal cost in energy. All the while, the components are electrically insulating, and ion conducting.

[0026] The elements that may be used as the ions in the solid-state battery discussed above can be, but are not limited to, lithium, iron, magnesium, aluminium, nickel, and sodium, where in each case ions of these elements are the charge carrier which transfer charge from the anode to the cathode during charging and from the cathode to the anode during discharge (use). For each material the combination of materials required for the cathode, solid electrolyte and anode changes.

[0027] The selection of materials for the cathode, solid electrolyte, and anode varies depending on the specific ion used. Ideally, the chemical composition of the solid electrolyte is engineered to transition from matching the anode's composition to the cathode's during synthesis, while maintaining this structure both after synthesis and throughout repeated charging and discharging cycles.

[0028] For a lithium ion battery an example of a cathode material would be cobalt lithium oxide and the most commonly the phases used are lithium transition metal oxides which have the alpha-NaFeO2 type structure. The general formula is normally written as LiA O2 (M = V,Cr,Fe,Co and Ni). In some cases, there are benefits of synthesizing mixtures of two or more metals on the M site and the method described here allows this type of cathode material.

[0029] In general cathode materials are typically oxides of transition metals, which can undergo oxidation to higher valences when lithium is removed. This is true for all cathode materials, they provide the stable sites that the ions are driven towards when the battery is in use and are driven from when the battery is being charged. For Li+ based batteries there are mainly three families of materials that have been most studied: layered LiCoO2 materials, LiMn2O4 spinels and then olivine structures with the composition LiMPO4 (M = Fe, Mn, etc.). They are considered by some to the most promising positive electrodes for lithium ion batteries. Generally the layered transition metal oxides are represented as LiMO2 with (M = Ni, Mn, Co, Al etc.). They have however not reached their full potential in e.g. the E.V.

[0030] There are a multitude of commercially used cathode materials that are either LiCoO2 synthesised with different methods or possibly derivatives of this base material. An example is the complex Li[Nio.8Coo.i5Alo.o5]02 (NCA) cathode.

[0031] An available syntheses route utilizing the method describe above would assume the cathode material to be synthesized with a given method, maximizing the performance of that layer as a cathode. This sample could then be transferred to a system where the gradient layer would be added. This system should then allow the composition of the depositing layer to vary from that of the cathode to that of the electrolyte, e.g. with the methods describe above.

[0032] Examples of solid lithium electrolytes include:Complex hydrides such as O.7Li(CB9Hio)O.3Li(CBnHi2),NASICON structure Lii+xAlxTi2-x(PO4)3 (LATP),Garnet structure, Li7La3Zr2Oi2(LLZO),LiPON, an oxynitride of L PO-iPerovskite structure [Li3xLaM-xTiO3(LLTO)],Anti-perovskite structure (L OCI).

[0033] The basic requirement of the electrolyte is to be electrically insulating and then provide fast ion transport. This applies regardless of which ion is being transported in which kind of a solid state battery.

[0034] The anode is the electrode the ions reside in when the battery is in its charged state. Commonly this is a slab of the metal ion the battery is based on e.g. Li, Mg, Fe, Al but commonly this is a scaffold or framework which allows the ions plenty of space to occupy without binding them too hard. Most commercial Li-ion batteries use graphite (LiCe) as the anode but other possible anode materials include: lithium transition metal oxides, vanadium oxides, lithium metal nitrides, silicon.

[0035] Currently there are a host of different anode materials under study but the overall goal of many research efforts seems to be to optimize the other components of the battery in order to allow the use of pure Li metal as the anode.

[0036] An alternative approach, and as mentioned previously, for synthesis a battery utilizing the proposed method is to synthesize sheets of a given composition of the cathode which vary in composition ranging from that of the cathode to that of the electrolyte and press them together for the type of step-wise change in composition between the cathode and the anode which would soften the transition from one to the other.

[0037] In an embodiment, the cathode, electrolyte and anode layers do not need to be deposited or synthesized in the same system or by the same method as the gradient layer that is applied between them. One approach would be to deploy a standard or known method to produce the cathode material layer. The sample / substrate / assembly could then be, as an example, transported to a deposition system capable of varying the composition of the atomic flux from that of the cathode composition to that of the electrolyte. Once this interface layer is finished and the final composition obtained mimics that of the electrolyte, the sample / substrate / assembly can be transported to the dedicated system used for the deposition of the electrolyte. Even if the conditions during this deposition do not allow the starting layer to have exactly the same structure as the cathode layer itself the abruptness of the interface will be significantly softer than between the cathode layer and the electrolyte directly.

[0038] Accordingly, based on the above, the solid-state battery and the method of manufacturing it is such that there are no interfaces between the anode, the solid electrolyte and the cathode. In this new design the composition changes gradually from that of the cathode to the electrolyte and finally to the anode. This increases the lifetime of solid state-battery significantly, since the interfaces are the source of most failures and reduction in performance.

[0039] Additionally, the charging and de-charging (how fast a battery can be charged and how much power it can deliver) is most often limited by the interfaces and the kinetics of ion transport across them. This problem is however eliminated, allowing the inherent kinetics of the materials involved to dictate these parameters. This would significantly reduce charging time and increase available peak power.

[0040] In general, the various aspects of the invention may be combined and coupled in any way possible within the scope of the invention. These and other aspects, features and / or advantages of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which

[0042] Figure 1 depicts graphically an example of a solid-state battery,

[0043] Figures 2 and 3 depict a solid-state battery according to the present invention,

[0044] Figure 4 illustrates graphically the smoothness between the anode, the first interface material, the solid electrolyte, the second interface material and the cathode as discussed in relation to figures 2 and 3, and

[0045] Figure 5 shows a flowchart of a method of manufacturing such a solid-state battery.DESCRIPTION OF EMBODIMENTS

[0046] Figure 1 depicts graphically an example of solid-state battery having three key layers, an anode 101, a solid electrolyte 103 and a cathode 103 supported by a substrate 106. Also shown is a cathode current collector 104 and anode current collector 105. This design may of course be different from what is shown here.

[0047] Embodiments illustrating how to improve ionic conductivity at the interfaces between the anode / cathode and the solid electrolyte and at the same time eliminating the interfacial challenges commonly encountered in such solid-state batteries in the scalability shown here, will be discussed below.

[0048] Figure 2 depicts an embodiment a solid-state battery 200 according to the present invention, comprising an anode 201 formed using an anode material, a cathode 203 formed using a cathode material and a solid electrolyte 202 arranged between the anode 201 and the cathode 203.

[0049] A preferred property for the solid electrolyte 202 is for it to be electrically insulating but a good ion conductor. Other preferred properties are that it has high mechanical strength, chemical stability, low material and processing costs, good interface compatibility, block redox species shuttling, suppression of dendrite growth, thermal stability and high ionic conductivity.

[0050] The solid-state battery 200 further comprises a first interface material 204 arranged between the anode 201 and the solid electrolyte 202 having first interface material side 205 facing the anode 201 and a second interface material side 206 facing the solid electrolyte 202.

[0051] The solid-state battery 200 further comprises a second interface material 207 arranged between the solid electrolyte 202 and the cathode 203 having first interface material side 208 facing the solid electrolyte 202 and a second interface material side 209 facing the cathode 203.

[0052] The first interface material side 205 of the first interface material 204 has an atomic composition which more or less consist of anode material and the second interface material side 206 of the first interface material 204 has an atomic composition which more or less consist of electrolyte material. The material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material, where the continuous gradient includes linearly varying atomic composition or non-linearly varying atomic composition.

[0053] The first interface material side 208 of the second interface material 207 has an atomic composition which more or less consists of electrolyte material and thesecond interface material side 209 of the second interface material 207 has an atomic composition which more or less consists of cathode material, where the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material, where the continuous gradient includes linearly varying atomic composition or non-linearly varying atomic composition.

[0054] It is important to note that the first interface material 204 and the second interface material 207 do not have abrupt boundaries, as suggested by the dotted box, which is included purely for illustrative purposes. This solid-state battery can be conceptualized as consisting of five distinct materials: the anode material 201, the first interface material 204, the solid electrolyte 202, the second interface material 207, and the cathode material. However, all these materials are seamlessly interconnected, forming a smooth and continuous structure.

[0055] As depicted in the zoomed up view 211 for the first interface layer 204, the first interface material comprises a stepped gradient chemical compound comprising a plurality of layers 210a-210g, where the continuous gradient in the atomic composition from the composition of the anode material to the atomic composition of the electrolyte material is generated by a different percentage of the anode material and the electrolyte material in each layer. Same applies for second interface material 207 (not shown as a zoomed-up view), where the continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material is generated by a different percentage of the electrolyte material and the cathode material in each layer. Moreover, as shown here, the first and the second interface materials 204. 207 have a gradient in atomic composition in the direction perpendicular to the interface material sides as indicate by the arrow 212, and where the composition in the directions parallel to the interface material sides is uniform.

[0056] Accordingly, the solid-state battery according to the present invention is without abrupt interfaces between the three main constituents of the battery, namely the anode 101, solid electrolyte 102 and the cathode 202.

[0057] Figure 3 illustrates example of materials for the three components for a solid- state battery according to the present invention, where Li anode is on the left 301, LiPON electrolyte 302 and then the LiCoCh cathode 303 on the right. As shown, the Li ions have been driven towards the anode where they find metastable sites among atoms from the electrolyte or they become part of the continuous Li metal layer. On the right the cathode material has been mostly striped from all the Li, and is now mainly the CO3O4 composition, albeit amorphous and porous allowing for the re-entry of the Li ions during discharging. Some of the advantages with this setup include, but are not limited to:There is no requirement that any of the components of a battery be a singlephase crystalline phase, they can all be amorphous. This means that there is no inherent need for e.g. a post-deposition annealing step allowing the crystallization of a stable phase simplifying all fabrication.The main difficulty in the design of solid-state batteries today is selecting materials that have the highest ion density and that the ions are loosely bound on the anode site and the opposite for the cathode. Ion current efficiency is also an issue, but the interfaces between these components is actually the greatest issue.The actual ion occupancy during deposition only dictates the state of the battery during synthesis, but this will change as soon as the battery is charged / discharged.By ensuring that during synthesis the correct amount of Li is present, i.e. that the battery is synthesized in its de-charged state, selective ion pathways will be a part of whatever structure results, ensuring fast and free flow of the ions in both directions.

[0058] Figure 4 illustrates graphically the smoothness between the anode 401 , the first interface material 404, the solid electrolyte 402, the second interface material 407 and the cathode 403 as discussed above, where these “5 -different materials” are “smoothed out” as indicated here. Also, shows is a cathode current collector 414 and an anode current collector 415.

[0059] Figure 5 shows a flowchart of a method according to the present invention for manufacturing a solid-state battery comprising an anode, a cathode and a solid electrolyte arranged between the anode and the cathode material.

[0060] In a first step (S 1) 501, a first interface material is produced between the anode and the solid electrolyte having a first interface material side facing the anode and a second interface material side facing the solid electrolyte. This may be done by depositing an anode material and an electrolyte material in a controlled way such that the first interface material side of the first interface material has an atomic composition essentially containing anode material and the second interface material side of the first interface material has an atomic composition essential containing electrolyte material. The controlling is preferably such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material.

[0061] In a second step (S2) 502, a second interface material is produced between the solid electrolyte and the cathode having first interface material side facing the solid electrolyte and a second interface material side facing the cathode. This may be done by depositing an electrolyte material and a cathode material in a controlled way such that the first interface material side of the second interface material has an atomic composition essentially containing electrolyte material and the second interface material side of the second interface material has an atomic composition essential containing cathode material. The controlling is preferably such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material.

[0062] It should be noted that the present invention is not limited to the sequence of the above-mentioned steps.

[0063] Said step of depositing the anode material and the electrolyte material, and the electrolyte material and the cathode material may include using chemical vapour deposition or physical vapour deposition.

[0064] Moreover, said step of depositing the anode material and the electrolyte material in a controlled way comprises adjusting the atomic or molecular flux of theanode material and the electrolyte material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a pre-defined time interval.

[0065] Further, said step of depositing the electrolyte material and the cathode material in a controlled way comprises adjusting the atomic or molecular flux of the electrolyte material and the cathode material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a pre-defined time interval.

[0066] Adjusting the atomic or molecular flux is obtained by one or more of the following: adjusting the power applied to a physical vapour deposition source over a time interval, or adjusting the pressure or flow of a precursor gas over a time interval, or adjusting a substrate temperature of a substrate on which the solid-state battery is built on or the substrate potential over a time interval.

[0067] Example:

[0068] When synthesizing a solid-state battery according to the present invention few a few key insights are required. First is that the entire structure is amorphous and can be deposited using reactive sputtering at room temperature. Reactive sputtering is simply the normal sputtering process, with Ar gas as the working gas but with the addition of oxygen in order to form oxides. These material combinations currently exist as commercial targets from most sputtering target manufacturers and so it is easy to synthesize each individual layer in the stack shown in figures 2 and 3 by sputtering from a single target. One could start with LiCoO2, and once the selected thickness was reached, the power over this target could be reduced while at the same time the LiPON target would be ignited and the power slowly increased. The amount of oxygen or nitrogen would possibly have to be adjusted using gas, but this is routine in reactive sputtering. Once the LiPON electrolyte target thickness had been reached, the power applied to this target would be slowly turned down and an Li target (or some other anode material) would be ignited, and the power increased.

[0069] With elemental targets a continuous battery may be designed in a more focused way. As an example is to start with co-depositing Lio.5Co02 as the working cathode,from elemental targets and then slowly reduce the Co (reduce the power applied to the Co target) for a target containing P (e.g. the original L PO-i) and add N (as another reactive gas) to make, in effect, the LiPON electrolyte. The recipe for the LiPON could be optimized prior in order to have a target set of parameters to aim for. This would then eventually be changed for Ti and Nb for the possible TiNb2O? anode.

[0070] The interfaces 204, 207 between the different components of the solid-state battery would move depending on the state of the charge of the battery across the interfaces since they are integrated. There just needs to be a driving force from one end of the battery to the other and that during charging there is capacity to store the ions there at a minimal cost in energy. All the while, the components are electrically insulating, and ion conducting.

[0071] One alternative solution to generate a higher capacity battery, one would need to move in such a continuous manner from e.g. V2O5, the cathode material measured with the highest capacity, through LiPON towards the Pure Li metal as the anode. On the anode side there are a host of materials mentioned, Sn, Ge and Si as well as the most common, C which fully lithiated takes the form LiCe. It also becomes possible to broaden the range of elements and compounds that are viable for battery fabrication due to less dependency on stable crystalline structures. This would also possibly reduce the need for elements that are scarce, faster but as the use of batteries is continually increasing the need of certain materials is putting immense pressure on the areas these materials are sourced from. This is true for instance for Co, which some large scale producers are gradually phasing out of their designs, often at a cost to performance.

[0072] Research show that it is possible to obtain an amorphous structure of some, or all of these materials, over a large range of lithium content such that the structure could be used as the anode. This is also a key insight regarding the viability of the idea, by focusing on an amorphous structure and by verifying the broad range in Li composition over which this structure is maintained, both the Li capacity as well as the ion-conduction naturally follow. Charging times for current battery designs are limited by interfaces since high ion currents flowing across them cause the typical degradation events that cause failure. Solid-state batteries are expected to suffer less from this issue with the proposed design eliminating it altogether.

[0073] While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

CLAIMS1. A solid-state battery cell, comprising: an anode, formed using an anode material, a cathode, formed using a cathode material, a solid electrolyte arranged between the anode and the cathode, formed using an electrolyte material, a first interface material arranged between the anode and the solid electrolyte, having a first interface material side facing the anode and a second interface material side facing the solid electrolyte, a second interface material arranged between the solid electrolyte and the cathode, having a first interface material side facing the solid electrolyte and a second interface material side facing the cathode, wherein the first interface material side of the first interface material has an atomic composition essentially containing anode material and the second interface material side of the first interface material has an atomic composition essentially containing electrolyte material, where the material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material, wherein the first interface material side of the second interface material has an atomic composition essentially containing electrolyte material and the second interface material side of the second interface material has an atomic composition essential containing cathode material, where the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material.

2. The solid-state battery cell according to claim 1, wherein the first and the second interface materials comprise a single -crystalline, polycrystalline, or amorphous atomic arrangement, and where the atoms constituting the first and the second interface materials form a chemical compound of varying atomic composition.

3. The solid-state battery cell according to claim 1, wherein the continuous gradient in the atomic composition for the first and the second interface materials includes linearly varying atomic composition or non-linearly varying atomic composition.

4. The solid-state battery cell according to claim 1, wherein the first interface material comprises a stepped gradient chemical compound comprising a plurality of layers, where the continuous gradient in the atomic composition from the composition of the anode material to the atomic composition of the electrolyte material is generated by a different percentage of the anode material and the electrolyte material in each layer.

5. The solid-state battery cell according to claim 1, wherein the second interface material comprises a stepped gradient chemical compound comprising a plurality of layers, where the continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material is generated by a different percentage of the electrolyte material and the cathode material in each layer.

6. The solid-state battery cell according to claim 1, wherein the first and / or the second interface material has a gradient in atomic composition in the direction perpendicular to the interface material sides, and where the composition in the directions parallel to the interface material sides is uniform.

7. A solid-state battery-enabled system comprising a solid-state battery according to claim 1.

8. A method of manufacturing a solid-state battery comprising an anode, a cathode, and a solid electrolyte arranged between the anode and the cathode material, comprising: producing a first interface material between the anode and the solid electrolyte having a first interface material side facing the anode and a second interface material side facing the solid electrolyte, where the step of producing comprises: depositing an anode material and an electrolyte material in a controlled way such that the first interface material side of the first interface material has an atomic composition essentially containing anode material and the second interface material side of the first interface material has an atomic composition essentially containing electrolyte material, and where the controlling is such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the anode material to the composition of the electrolyte material, producing a second interface material between the solid electrolyte and the cathode having a first interface material side facing the solid electrolyte and a second interface material side facing the cathode, where the step of producing comprises: depositing an electrolyte material and a cathode material in a controlled way such that the first interface material side of the second interface material has an atomic composition essentially containing electrolyte material and the second interface material side of the second interface material has an atomic composition essentially containing cathode material, and where the controlling is such that the material composition there between comprises a continuous gradient in atomic composition from the composition of the electrolyte material to the composition of the cathode material.

9. The method of claim 8, wherein the step of depositing the anode material and the electrolyte material, and the electrolyte material and the cathode material, comprises using chemical vapour deposition or physical vapour deposition.

10. The method according to claim 8, wherein the step of depositing the anode material and the electrolyte material in a controlled way comprises adjusting the atomic or molecular flux of the anode material and the electrolyte material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a predefined time interval.

11. The method according to claim 8, wherein the step of depositing the electrolyte material and the cathode material in a controlled way comprises adjusting the atomic or molecular flux of the electrolyte material and the cathode material, or their precursors, towards the electrolyte layer continuously and / or step-wise over a predefined time interval.

12. The method according to claim 10, wherein the step of adjusting the atomic or molecular flux is obtained by one or more of the following: adjusting the power applied to a physical vapour deposition source over a time interval, or adjusting the pressure or flow of a precursor gas over a time interval, or adjusting a substrate temperature of a substrate on which the solid-state battery is built or the substrate potential over a time interval.

13. The method according to any of the claim 8, further comprising producing the anode from an anode material, or the cathode from a cathode material, or the solid electrolyte from an electrolyte.

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