WO2020095239A1

WO2020095239A1 - A solid-state battery

Info

Publication number: WO2020095239A1
Application number: PCT/IB2019/059564
Authority: WO
Inventors: Pasquale Forte; Erik KOEP
Original assignee: Eldor Corporation S.P.A.; S2 Batteries Llc
Priority date: 2018-11-07
Filing date: 2019-11-07
Publication date: 2020-05-14
Also published as: EP3878031A1; CN113853697A; IT201800010128A1

Abstract

A solid-state battery comprising a positive electrode (2), a negative electrode (3), and an electrolyte (4) interposed between said positive (2) and negative (3) electrodes. At least one of either the positive electrode (2), the negative electrode (2), or the electrolyte (4) is defined by a thin film made of a ceramic material exhibiting high ionic conductivity. The thin film is of the monolithic type and has a carbon content ranging from 0.1% to 10% in atomic percent. The thin amorphous material can, alternatively, be used to form the base of a wide variety of devices, such as fuel cells, sensors, and membranes.

Description

A SOLID-STATE BATTERY

Technical Field

This invention relates to a thin ceramic film, preferably used in a solid-state battery, more preferably in a solid-state battery of the lithium-ion type.

This invention has its main application in the automotive sector, but can, in general, be associated with other areas too.

In fact, thin ceramic films have many significant commercial applications, such as, for example, barrier coatings in anti-corrosion or heat-resistant applications, or even as electrolytes for electrochemical devices.

Prior art

With reference to the technical field that is most important for the purposes of this invention, batteries in the automotive sector usually consist of a positive and negative electrode separated by an ionically conductive but electrically insulating electrolyte.

As is well known, batteries can be of the "primary" or "secondary" type, depending on whether or not they can be recharged, i.e. according to the type of chemical reaction underlying the ion movement and that, in the case of secondary batteries, must be reversible.

Secondary batteries, which are the focus of this invention, are available in a wide variety of types and sizes, but are generally defined by the mobile ion. Therefore, secondary lithium batteries are typically based on the conduction of the mobile lithium ion.

The electrolyte interposed between the two electrodes can be of the liquid or solid type.

The so-called "thin films", usually of the amorphous type, are generally used as solid electrolytes, since the edges of the grains tend to prevent the movement of lithium ions within the electrolyte.

In fact, considering that lithium is propagated in solid-state ionic conductors by means of an interstitial method, amorphous or nanocrystalline materials show consistently higher ionic conductivity than their crystalline counterparts.

The development and use of thin films have recently, therefore, become increasingly important, which has led to the production of thin films of various thicknesses (from a few nanometres to several microns) and composed of a wide variety of materials.

Disadvantageously, however, the thin films on the market today, or otherwise presented in studies of the sector, have significant drawbacks, first of all, the high cost of production.

In fact, the thin films currently on the market, or otherwise presented in studies of the sector, necessitate long deposition times and very high production costs. For this reason, although solid-state batteries have shown remarkable performance in the aerospace and defence industries, they have, so far, been little used in the microelectronics and automotive sectors, which, in terms of numbers, are obviously much more significant from the point of view of economics.

The purpose of the present invention is therefore to provide a thin ceramic film and a solid-state battery that overcome the drawbacks of the prior art described above.

In particular, the purpose of this invention is to make available a thin ceramic film and a high-performance solid-state battery, which are, at the same time, economical to produce.

Said purposes are achieved by a solid-state battery exhibiting the characteristics of one or more of the following claims from 1 to 17.

In particular, the battery comprises a positive electrode, a negative electrode, and an electrolyte interposed between said electrodes.

According to one aspect of this invention, at least one of either the positive electrode (cathode), the negative electrode (anode), or the electrolyte is defined by a thin film made of amorphous, inorganic material exhibiting high ionic conductivity and electric isolation. According to an additional aspect of the invention, which is alternative to or complementary to the preceding one, the thin film of inorganic amorphous material contains an alkaline metal, a metalloid, or non-metal forming the glass and an anionic species.

The alkaline metal is preferably lithium or sodium.

The metalloid or non-metal is preferably an element from Group 13, Group 14, Group 15, or Group 16 of the periodic table.

The anionic species is preferably a chalcogen or from the nitrogen group. The ionic species is preferably oxygen.

The thin film preferably has a carbon content ranging from 0.1 % to 10% in atomic percent.

More preferably, the carbon content is lower than 2% in atomic percent, i.e. ranging from 0.1 % to 2% in atomic percentage.

It should be noted that the carbon particles within the thin film are preferably evenly distributed so that the ceramic film is of the monolithic type.

In other words, by examining the thin film by means of appropriate analysis techniques it is not possible to identify markedly different areas of carbon concentration, except, of course, for small variations that are entirely random.

Film analysis techniques can be, for example, X-ray photoelectron spectroscopy (XPS) or secondary-ion mass spectrometry (SIMS), thanks to which it is possible to analyse the stoichiometry and crystallography of thin films, enabling a detailed analysis of the chemical composition of the materials.

Brief description of the drawings

These and other features, together with their advantages, will be clearer from the following illustrative, and therefore non-limiting, description of a preferred, and therefore non-limiting, embodiment of a thin ceramic film and of a solid-state battery as illustrated in the attached Figure 1 , which schematically shows the composition of a solid-state battery according to this invention.

Description of a preferred embodiment

With reference to the attached figure, the number 1 denotes a solid-state battery according to this invention.

This battery 1 is, preferably, a secondary (i.e. rechargeable) lithium-ion (or lithium) battery. More preferably, this battery 1 is of the intercalated type. The intercalated battery is a specific type of secondary lithium battery, wherein both the anode and the cathode are composed of intercalation compounds that, in the case of lithium batteries, are defined by impregnated or intercalated elemental lithium, rather than being directly applied.

The structure of the battery 1 in the solid state with thin films involves the presence of a positive electrode 2, or cathode, a negative electrode 3, or anode, and an electrolyte 4 interposed between them.

In the preferred embodiment, the positive electrode 2, electrolyte 4, and negative electrode 3 are stacked sequentially to create an electrochemical storage device. When the current collectors are connected to a prescribed load, the battery 1 is discharged, enabling the lithium ions to pass from the anode to the cathode and to force the electrons through the electrical circuit.

According to the invention, at least one of either the positive electrode 2, the negative electrode 3, or the electrolyte 4 is defined by a thin film made of a ceramic material exhibiting ionic conductivity and electric isolation.

Said thin film is preferably, made of amorphous ceramic material, which is also the object (independent) of this invention and better described below. The thin film made of inorganic amorphous material preferably contains an alkaline metal, a metalloid, or non-metal forming the glass and an anionic species. The metalloid or non-metal is preferably an element from Group 13, Group 14, Group 15, or Group 16 of the IUPAC periodic table.

The alkaline metal is preferably lithium or sodium.

In the embodiments using lithium, sample compounds are UBO2, UPO3, Li6Si07Li2Ge03, UAIO2, and U2SO4. The polymorphs of the previous compounds, such as U3BO3, LUBOs, U6B4O9, U3B11O18, LUP2O7, Li6Si207 are also excellent examples.

In the embodiments using sodium, sample compounds are Na3B03, Na3P03, Na4Si04, LUGe04, UAIO2 e Na2S04. The polymorphs of the preceding compounds are also excellent examples. Doping the B site can improve performance. Examples include (1 -x) UBO2-XU2SO4 e (1 -x) UBO2-XUPO3. Polymorphs of amorphous glasses doped at site B can also be used.

Returning to the battery, in the preferred embodiment, both the positive electrode 2 and the negative electrode 3, and the electrolyte 4, are defined by thin films of ceramic material.

Alternatively, however, only the electrolyte 4 could be made from said thin ceramic film.

The thickness of the electrolyte 4 typically ranges from 100 nm to 50 pm and is continuous enough to prevent contact between the positive 2 and negative 3 electrodes.

The negative electrode 3 can, for example, be made from ceramics or organic/inorganic glass with mixed ionic/electronic conduction properties, such as graphite, silicon, silicon alloys (U22SU), lithium titanium (LUTisO-^), lithium metal (Li), or indium (In).

In its preferred embodiment, however, the negative electrode 3 is made of amorphous carbon

The positive electrode 2 can, for example, be made from inorganic ceramics with mixed ionic/electronic conduction properties, preferably amorphous vanadium oxide (V2O5), lithium nickel manganese oxide (Li2Mn3Ni08), or, alternatively, lithium cobalt oxides (UC0O2) or NCA (Li(NiCoAI)0₂).

The electrolyte 4 can, for example, be made from inorganic, lithium-ion conductive and electronically insulating ceramics.

The material used is preferably amorphous lithium metaborate (UB02). Alternatively, however, one of the following, other compounds could also be used: amorphous lithium phosphate glass, amorphous lithium glass, lithium conduction garnet (such as LLZO, LizLa3Zr20i2), lithium phosphate (U3PO4), or lithium sulphide (U2S).

In other embodiments, the thin films listed above could be replaced by other ceramic films, such as metal oxides for condensers such as Ru02 and ZrSnTi04, insulators such as Zr02 and AI2O3, or others.

The central aspect of this invention is that at least the electrolyte 4, but preferably also the positive electrode 2 and the negative electrode 4, have a carbon content ranging from 0.1 % to 10% in atomic percentage, more preferably ranging from 0.1 % to 2%.

In the embodiment described here, however, the carbon content is about 7% in atomic percentage.

In particular, unlike what can be happen in known materials, where the accidental presence of carbon particles is still possible, the carbon particles 5 within the thin film according to the invention are evenly distributed so that the ceramic film is of the monolithic type.

A substrate and an electrode are prepared, on which the electrolyte is then deposited in the form of a thin amorphous film, preferably by pyrolysis in a flame spray (Flame Spray Pyrolysis), thanks to which it is possible to see the carbon particles 5 uniformly distributed in the material. As a result, the other electrode is deposited on top of the electrolyte 4 to form a current collector.

The invention achieves its intended purposes and significant advantages are thus obtained.

In fact, the production of a solid-state battery equipped with one or more overlapping thin films made as described above is highly performing and, at the same time, economical to produce.

Moreover, the preparation of a thin ceramic film composed of an inorganic amorphous material containing an alkaline metal, a metalloid, or non-metal forming the glass and an anionic species makes the film extremely economical to produce.

Claims

1. A solid-state battery comprising:

- a positive electrode (2);

- a negative electrode (3);

- an electrolyte (4) interposed between said positive (2) and negative (3) electrodes;

wherein said at least one of either the positive electrode (2), the negative electrode (2), or the electrolyte (4) is defined by a thin film made of a ceramic material exhibiting ionic conductivity,

characterised in that said thin film is of the monolithic type and has a carbon content ranging from 0.1 % to 10% in atomic percent.

2. The battery according to claim 1 , wherein only the electrolyte (4) is defined by a thin monolithic film of ceramic material exhibiting high ionic conductivity and has a carbon content ranging from 0.1 % to 10% in atomic percent.

3. The battery according to claim 1 , wherein both the positive electrode (2) and the negative electrode (3), and the electrolyte (4), are defined by thin films of ceramic material.

4. The battery according to any one of the preceding claims, wherein said thin film is made of amorphous ceramic material exhibiting ionic conductivity.

5. The battery according to any one of the preceding claims, wherein said carbon content is defined by a plurality of carbon particles (5) evenly distributed within the thin film.

6. The battery according to any one of the preceding claims, wherein the negative electrode (3) is made of organic or inorganic ceramic or glass material exhibiting mixed ionic/electronic conductivity.

7. The battery according to any one of the preceding claims, wherein the positive electrode (2) is made of inorganic ceramic material exhibiting mixed ionic/electronic conductivity, preferably selected from the following:

- lithium cobalt oxide (UC0O2),

- NCA (Li(NiCoAI)0₂).

- LMNO (LiMn1.5Nio.5O4)

8. The battery according to any one of the preceding claims, wherein the electrolyte (4) is made of inorganic, electronically insulating, lithium-ion conductive ceramic material.

9. The battery according to any one of the preceding claims, wherein the electrolyte (4) is made of amorphous lithium metaborate (LiBo2).

10. The battery according to any one of the preceding claims, wherein said thin film has a carbon content ranging from 0.1 % to 2% in atomic percent.

1 1. The battery according to any of the preceding claims, wherein said thin film has ionic conductivity of at least 1 x1 O ⁸ S/cm and electronic conductivity of less than 1 x1 O ¹⁰ S/cm.

12. The battery according to any one of the preceding claims, wherein said thin film has a mass crystallinity lower than 10%.

13. The battery according to any of the preceding claims, wherein said thin film has a thickness of less than 10 microns.

14. The battery according to any of the preceding claims, wherein said thin film comprises an alkaline metal, a metalloid, or a non-metal forming a glass and an anionic species.

15. The battery according to claim 14, wherein the alkaline metal is lithium or sodium.

16. The battery according to claim 14 or 15, wherein the metalloid or non- metal is classified in groups 13, 14, 15, or 16 of the IUPAC periodic table.

17. The battery according to any of the claims from 14 to 16, wherein the anionic species is oxygen.