KR20100036280A - Solid-state battery and method for manufacturing of such a solid-state battery - Google Patents

Abstract

Batteries based on solid-state electrolytes are known in the art. These (planar) energy sources, or solid-state batteries, efficiently convert chemical energy into electrical energy and can be used as the power sources for portable electronics. The invention relates to a method for manufacturing of a solid-state battery. The invention also relates to a battery obtained by performing such a method. The invention further relates to an electronic device provided with such a battery.

Description

SOLID-STATE BATTERY AND METHOD FOR MANUFACTURING OF SUCH A SOLID-STATE BATTERY}

The present invention relates to a method for manufacturing a solid state battery. The invention also relates to a battery obtained by performing the method. The invention further relates to an electronic device provided with the battery.

Batteries based on solid electrolytes are known in the art. These (planar) energy sources, or 'solid batteries', can efficiently convert chemical energy into electrical energy and be used as power sources for portable electronics. These batteries of small size can be used to supply electrical energy, for example, to microelectronic modules, in particular integrated circuits (IC). An example of this is disclosed in international patent application WO2005 / 027245, wherein a solid thin film battery, in particular a lithium ion battery, comprises a structured silicon substrate on which a stack of silicon anodes, solid electrolytes, and cathodes are successively deposited. An example of a suitable solid electrolyte is LiPON (lithium phosphorus oxynitride). Now, LiPON is one of the most possible and most used electrolytes for all solid lithium ion batteries. This material is a good insulator for electrons (σ _el = 10 ^-14 S / cm at 25 ° C), and a relatively good conductor compared to lithium ions (compared to other solid electrolytes) (σ _ion at 25 ° C). = 2 · 10 ^-6 S / cm). In addition, LiPON is electrochemically stable. However, the lithium ion conductivity of most liquid electrolytes is about twice as high as LiPON. Nevertheless, the performance of solid electrolytes can still approach (or perhaps exceed) the performance of liquid electrolytes because the solid electrolytes can be made very thin and the resistance of the solid electrolyte decreases as the electrolyte thickness decreases. ). For this reason, it is important to make the solid electrolyte as thin as possible, unless the breakdown field on the electrolyte is exceeded. However, it has been found that depositing pinhole-free LiPON layers with a thickness of less than 1 micron is very difficult, where a single pinhole in a solid electrolyte can generate shorted electrodes, thus generating a shorted battery. It is well known. Thus, in order to prevent the formation of pinholes in the electrolyte layer and thus to prevent a shorted battery, all existing solid batteries have in common an electrolyte layer with a safe thickness of about 3 microns or thicker.

It is an object of the present invention to provide an improved method for manufacturing all solid state batteries comprising a relatively thin pinhole free electrolyte layer.

It is an object of the invention to A) deposit a first electrode on a substrate, B) deposit a solid electrolyte layer on the first electrode, and C) deposit a second electrode on the solid electrolyte. It can be achieved by providing a method according to the present incorporating wherein step B) comprises steps D) and E), and step D) comprises a solid electrolyte layer having an initial layer thickness exceeding the desired final layer thickness. And depositing on the first electrode, step E) comprising reducing the initial layer thickness of the electrolyte layer deposited during step D) to the final layer thickness. First by depositing a sufficiently thick relatively thick electrolyte layer for safe erasure of the pinholes, and subsequently reducing the thickness of the relatively thick pinhole-free electrolyte layer to the desired final thickness (by removing excess electrolyte material) An electrolyte layer can be produced. The relatively thin solid electrolyte layer of the battery obtained by carrying out the method according to the invention reduces the resistance of the electrolyte and thus reduces the resistance of such a battery, which will benefit the performance of the battery. In order to prevent the formation of pinholes in the electrolyte layer, it is generally suitable to initially deposit a sufficiently thick electrolyte layer. In this way, the pinholes initially formed in the electrolyte layer are filled and closed by the electrolyte material, so that the pinhole-free electrolyte layer can be realized. It is conceivable to apply an electrolyte layer with an initial thickness of one or several micros. However, applying an electrolyte layer with an excess initial layer thickness is generally not preferred because this results in a relatively large excess of electrolyte material, thus generating a significant loss of material (during step E). Therefore, it is generally desirable to deposit an electrolyte layer sufficient for the initial layer thickness to prevent pinhole formation, since the final loss of electrolyte material can be kept to a minimum in this way. For this purpose, it is desirable to deposit a solid electrolyte layer in which an initial layer thickness of at least 500 nm is deposited on the first electrode during step D). The initial layer thickness of the solid electrolyte layer during step E) is preferably reduced to a final layer thickness of preferably 500 nm, preferably 100 nm, more preferably less than 60 nm. In this way, a significant reduction in the impedance of the electrolyte layer can be achieved, resulting in significantly improved battery performance.

In a preferred embodiment of the method according to the invention, the thickness of the solid electrolyte layer is reduced by etching back the electrolyte layer to the desired final layer thickness during step E). In general, etching techniques such as dry etching and wet etching are known for patterning layers, where etching techniques are commonly combined with conventional photolithographic masking. In an alternative embodiment, the excess electrolyte material is removed by polishing techniques, in particular by chemical-mechanical polishing (“CMP”) techniques, where the removable pads are biased against the electrolyte surface to be polished and slurry The insertion of microparticles includes fine-sized abrasive particles (and other raw materials) in between. As a result of the CMP treatment, the layer thickness of the electrolyte layer can also be reduced to the desired final thickness.

The solid electrolyte is preferably _{Li 5 La 3 Ta 2 O 12} ( garnet-type _{rating), LiPON, LiNbO 3, LiTaO} 3, Li 9 SiAlO 8, and _{Li 0 .5 La 0 .5 TiO 3} ( perovskite - Type) and at least one material selected from the group consisting of: Other solid electrolyte materials that can be preferably applied are lithium ortho tungstate (Li ₂ WO ₄ ), lithium germanium oxynitride (LiGeON), Li ₁₄ ZnGe ₄ O ₁₆ (lysicon), Li ₃ N, beta-alumina, or _{Li 1 .3 Ti 1 .7 Al 0} . ₃ (PO ₄ ) ₃ (nacicon-type). The proton conductive electrolyte can be formed, for example, by TiO (OH), or ZrO ₂ H _x .

The first electrode commonly comprises a cathode and the second electrode commonly comprises an anode (or vice versa). In a preferred embodiment, the cathode is made of at least one material selected from the group consisting of LiCoO ₂ , LiMn ₂ O ₄ , LiFePO ₄ , V ₂ O ₅ , MoO ₃ , WO ₃ , and LiNiO ₂ . It has been found that at least these materials are very suitable for application to lithium ion energy sources. Examples of cathodes for proton based energy sources are Ni (OH) ₂ and NiM (OH) ₂ , where M is formed by one or more elements selected from the group of, for example, Cd, Co, or Bi. It can also be clear that other cathode materials can be used in the battery obtained by the method according to the invention. The anode is preferably Li metal, Si-based alloys, Sn-based alloys, Al, Si, SnO _x , Li ₄ Ti ₅ O ₁₂ , SiO _x , LiSiON, LiSnON, and LiSiSnON, in particular Li _x SiSn _0.87 O _It is made of at least one material selected from the group consisting of _1.20 N _1.72 .

Preferably, at least one electrode of the energy source according to the invention is applied for the storage of at least one active species of the following elements: hydrogen (H), lithium (Li), beryl rate (Be), magnesium (Mg) ), Aluminum (Al), copper (Cu), silver (Ag), sodium (Na), and potassium (K), or any other suitable element assigned to group 1 or group 2 of the periodic table. Thus, the battery obtained by the method according to the invention can be based on a variety of insertion mechanisms and therefore can be used for other types of (stock-type) battery cells, for example Li-ion battery cells, NiMH battery cells and the like. Suitable for forming. In a preferred embodiment the at least one electrode, in particular the battery anode, comprises at least one of the following materials: C, Sn, Ge, Pb, Zn, Bi, Sb, Li and preferably doped Si. Combinations of these materials can also be used to form the electrode (s). Preferably, n type or p type doped Si is used as the electrode, or doped Si related compounds such as SiGe or SiGeC are used as the electrode. Other suitable materials may also be applied as anodes, and any other suitable element assigned to one of groups 12-16 of the periodic table as an anode, if the electrode material of the battery is applied for insertion and storage of the reactive species described above Can be applied. The materials described above are particularly suitable for application to lithium ion based battery cells. When a hydrogen based battery cell is applied, the anode comprises a hydride forming material such as AB ₅ -type materials, in particular LaNi ₅ , and magnesium-based alloys, in particular Mg _x Ti _{1- x} .

The method preferably further comprises steps F) and G), wherein step F) comprises depositing a first current collector on the substrate prior to deposition of the first electrode according to step A), and step G) Depositing a second current collector over the second electrode after depositing the second electrode according to step C). The current collectors allow the battery to be easily connected to the electronic device. Preferably, the current collectors are made of at least one of the following materials: Al, Ni, Pt, Au, Ag, Cu, Ta, Ti, TaN and TiN. Other kinds of current collectors can also be applied, for example, preferably doped semiconductor materials such as Si, GaAs, InP.

In a preferred embodiment, the method further comprises step H), wherein step H) comprises depositing an electron-conductive barrier layer on the substrate prior to the deposition of the first electrode according to step A), wherein the barrier layer is It is adapted to at least substantially prevent the diffusion of active species contained by the first electrode in the substrate. In this way, the substrate and the electrochemical cell will be chemically separated, so that the performance of the electrochemical cell can be kept relatively long lasting. When a lithium ion based cell is applied, the barrier layer is preferably made of at least one of the following materials: Ta, TaN, Ti, and TiN. It may also be clear that other suitable materials may be used to act as the barrier layer. In general, it would be desirable to dispose a barrier layer between the anode and an adjacent substrate.

In a preferred embodiment the substrate is applied and the substrate is ideally suited for application to surface treatments for patterning substrates which can facilitate the patterning of the electrode (s). The substrate is more preferably made of at least one of the following materials: C, Si, Ti, Ge, Al, Cu, Ta and Pb. Combinations of these materials can also be used to form the substrate (s). Preferably, n type or p type doped Si or Ge is used as the substrate, or doped Si related compounds and / or Ge related compounds such as SiGe or SiGeC are used as the substrate. In addition to the relatively rigid material, and Kapton ^® foil substantially flexible material, such can be used for the preparation of the substrate. It may also be clear that other suitable materials may be used as the substrate material.

In a particularly preferred embodiment the surface of at least one electrode facing the electrolyte is at least partially patterned. In this way the effective contact surface area between the electrode (s) and the electrolyte is substantially increased in relation to the typical relatively soft contact surface of the electrode (s), proportional to the rated capacity of the battery obtained by the method according to the invention. Causes an increase. Patterning the surface of one or multiple electrodes facing the electrolyte may be implemented by various methods such as selective wet chemical etching, physical etching (reactive ion etching), mechanical imprinting, and chemical mechanical polishing (CMP). Can be. The pattern of electrode (s) that increases the contact surface area between the electrode (s) and the electrolyte can be shaped in various ways. Preferably, the patterned surface of the at least one electrode is provided with a plurality of cavities, in particular pillars, trenches, slits or holes, in particular the cavities can be applied in a relatively accurate manner. have. In this way the increased performance of the battery can also be predetermined in a relatively accurate manner.

The invention also relates to a battery obtained by carrying out the method according to the invention comprising a first electrode, an electrolyte layer and a second electrode which is subsequently deposited on a substrate. The electrolyte layer is preferably relatively thin, wherein the thickness of the electrolyte layer is less than 500 nm, preferably less than 100 nm, more preferably less than 60 nm, and particularly preferably substantially 50 nm. In addition, the electrolyte layer is substantially homogeneous (no pinholes) to prevent short circuits of the first and second electrodes. Other (preferred) embodiments and advantages of the battery according to the invention have already been disclosed above.

The invention also relates to an electronic device provided with at least one battery according to the invention and at least one electronic component connected to the battery. At least one electronic component is preferably at least partially inserted into the substrate of the battery. In this way a system in a package (Sip) can be implemented. In SiP, one or more electronic components and / or devices, such as integrated circuits (ICs), actuators, sensors, receivers, transmitters, and the like, are at least partially embedded in a substrate of a battery in accordance with the present invention. The battery according to the invention is ideally suited for relatively small high power electronic applications such as (bio) implants, hearing aids, autonomous network devices, and nerve and muscle stimulation devices, and textile electronics, washable electronics, preformed batteries Is suitable for providing power to flexible electronic devices such as a host of applications requiring e-paper, e-paper and portable electronic applications.

The invention is illustrated by the following non-limiting examples.

1 shows a cross-sectional view of a known solid battery comprising a relatively thin electrolyte layer.

2a to 2d show the manufacture of a battery according to the invention;

1 shows a schematic cross-sectional view of a battery 1 known from the prior art. An example of the battery 1 shown in FIG. 1 is also disclosed in international patent application WO2005 / 027245. The known battery 1 comprises a lithium ion cell stack 2 of an anode 3, a solid electrolyte 4, and a cathode 5, the cell stack 2 comprising one or more electronic components ( 7) is disposed on the substrate 6 on which it is embedded. In this embodiment, the substrate 6 is made of native silicon and the anode 3 is made of amorphous silicon (a-Si). The cathode ₅ is made of V ₂ O ₅ and the solid electrolyte is made of LiPON. A lithium barrier layer 8 is deposited over the substrate 6 between the battery stack 2 and the substrate 6. In this example, the lithium diffusion barrier layer 8 is made of tantalum. The conductive tantalum layer 8 acts as a chemical barrier because this layer prevents the diffusion of lithium ions (or other active species) initially contained by the stack 2 into the substrate 6. When lithium ions leave the stack 2 and enter the substrate 6, the performance of the stack 2 is affected. In addition, this diffusion severely affects the electronic component (s) 7 embedded in the substrate 6. In this embodiment, the lithium diffusion barrier layer 8 also acts as a current collector for the anode 3 in the known battery 1. The battery 1 further comprises an additional current collector 9 made of aluminum deposited on top of the battery stack 2 and in particular on top of the cathode 5. Deposition of the individual layers 3, 4, 5, 8, 9 can be accomplished by, for example, CVD, sputtering, E-beam deposition or sol-gel deposition. In this embodiment, a relatively thin electrolyte layer 4 with a thickness of about 100 nm is deposited over the anode 3. The advantage of applying a relatively thin electrolyte layer 4 is the relatively small resistance of this layer 4 which is desirable for the performance of the battery. However, a substantial risk of depositing a relatively thin electrolyte layer is the formation of pinholes 10 in the electrolyte layer 4 causing short circuits of the anode 3 and the cathode 5. Thus, conventional thin film all solid-state batteries generally have thicker electrolyte layers (about a few microns) compared to electrolyte layer 4 as shown by loss of battery performance to prevent pinhole formation in electrolyte layer 4. Is equipped.

2a to 2d show the manufacture of a battery 11 according to the invention. In FIG. 2A it is shown that the barrier layer 12, the anode 13, and the solid electrolyte 14 are subsequently deposited on the substrate 15 with one or more electronic components 16. As shown in this figure, an initially relatively thick electrolyte layer 14 as compared to the desired final layer thickness (shown in dashed lines) is deposited on the anode 13 to adhere the pinhole-free electrolyte layer 14. do. The initial thickness of electrolyte layer 14 is about 500 nm in this embodiment. The upper surface of the electrolyte layer 14 may have irregularities 17. To remove these irregularities 17, the electrolyte layer 14 is planarized by conventional etching and / or polishing techniques (see FIG. 2B). After planarization of the electrolyte layer 14, the thickness of the layer 14 is reduced (in addition) to a desired layer thickness of, for example, 50 nm (see FIG. 2C). This relatively thin electrolyte layer 14 will be free of pinholes and thus can physically separate the anode 13 and cathode 18 to be deposited on the electrolyte 14 (FIG. 2D). A current collector 19 is deposited on top of cathode 18. The relatively thin electrolyte layer 14 will have a relatively small resistance which would be desirable for the performance of the battery 1 according to the invention. Thus by carrying out the method according to the invention a relatively thin high performance battery 11 can be manufactured in a relatively simple and effective manner.

It is noted that the above-described embodiments illustrate rather than limit the invention, and that those skilled in the art can design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. The use of the verb "comprise" and its utilization does not exclude the presence of elements or steps other than those stated in a claim. Singular articles preceding an element do not exclude the presence of a plurality of such elements. The simple fact that certain measures are listed in different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims (18)

As a method for manufacturing a solid state battery, A) depositing a first electrode on the substrate, B) depositing a solid electrolyte layer on the first electrode, and C) depositing a second electrode on said solid electrolyte, Said step B) comprises steps D) and E), said step D) comprising depositing a solid electrolyte layer with an initial layer thickness exceeding a desired final layer thickness on said first electrode, Wherein said step E) comprises reducing an initial layer thickness of an electrolyte layer deposited during said step D) to said final layer thickness. The method of claim 1, During the step D), the solid electrolyte layer having an initial layer thickness of at least 500 nm is deposited on the first electrode. The method according to claim 1 or 2, During the step E), the initial layer thickness of the solid electrolyte layer is reduced to a final layer thickness of less than 500 nm, preferably of 100 nm, more preferably of less than 60 nm. 4. The method according to any one of claims 1 to 3, The thickness of the solid electrolyte layer during step E) is reduced by etching back the electrolyte layer to the desired final layer thickness. The method according to any one of claims 1 to 4, During the step E), the thickness of the solid electrolyte layer is reduced by polishing the electrolyte layer to the desired final layer thickness. 6. The method according to any one of claims 1 to 5, Wherein the first electrode is formed by an anode and the second electrode is formed by a cathode. 7. The method according to any one of claims 1 to 6, The method for manufacturing a solid battery further comprises the step F) and the step G), wherein step F) comprises depositing a first current collector on the substrate before deposition of the first electrode according to step A). Wherein said step G) comprises depositing a second current collector on said second electrode after depositing said second electrode according to said step C). 8. The method according to any one of claims 1 to 7, The method further comprises the step H) comprising depositing an electron-conductive barrier layer on the substrate prior to the deposition of the first electrode according to step A), wherein the barrier layer is formed into the substrate. A method of manufacturing a solid battery, adapted to at least substantially prevent diffusion of active species contained by one electrode. A battery obtained by performing the method according to any one of claims 1 to 8, A battery comprising a first electrode, an electrolyte layer, and a second electrode subsequently deposited on a substrate. The method of claim 9, And the electrolyte layer is substantially homogeneous. 11. The method according to claim 9 or 10, The thickness of the electrolyte layer is less than 500 nm, preferably 100 nm, more preferably less than 60 nm. The method according to any one of claims 9 to 11, The solid electrolyte is Li ₅ La ₃ Ta ₂ O ₁₂ , LiPON, LiNbO ₃ , Li ₃ N, beta-alumina, Li _1.3 Ti _1.7 Al _0.3 (PO ₄ ) ₃ LiTaO ₃ , LiGeON, Li ₂ WO ₄ , Li ₁₄ ZnGe ₄ O ₁₆ , _{Li 9 SiAlO 8, Li 0 .5} La 0 .5 TiO 3, TiO (OH), ZrO _2, and is made of at least one material selected from the group consisting of H _x, the battery. The method according to any one of claims 9 to 12, At least one of the first and second electrodes is adapted for storage of ions of at least one of H, Li, Be, Mg, Cu, Ag, Al, Na and K elements. The method according to any one of claims 9 to 13, At least one of the first and second electrodes is made of at least one of C, Sn, Ge, Pb, Zn, Bi, Sb, and preferably doped Si materials. The method of claim 14, And the substrate comprises Si. An electronic device provided with at least one battery according to any one of claims 9 to 15. The method of claim 16, The at least one electronic component, in particular an integrated circuit (IC), is at least partially embedded in the substrate of the battery. 18. The method according to claim 16 or 17, The electronic device and the battery form a system in a package (SiP).

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