GB2601779A

GB2601779A - Electrolyte material with LiPON-coated particles, battery cell, and method for manufacturing the electrolyte material

Info

Publication number: GB2601779A
Application number: GB2019438.7A
Authority: GB
Inventors: Glossmann Tobias; Chang Hansen
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2020-12-10
Filing date: 2020-12-10
Publication date: 2022-06-15
Also published as: GB202019438D0; WO2022122309A1

Abstract

An electrolyte material 1 for a battery cell 2 comprises a plurality of solid particles 7 coated with a lithium-based nitride 8. The lithium-based nitride is preferably a lithium phosphorus oxynitride (LiPON), but may also comprise a lithium silicon phosphorous oxyntride (LiSiPON) and/or lithium silicon phosphorous hydronitride (LiSiPHN). The solid particles are preferably made of a solid sulfide or oxysulfide compound and is preferably a LGPS-type material such as Li10GeP2S12. The nitride coating is preferably applied to the solid particles using atomic layer deposition (ALD). A battery cell comprising a lithium metal anode 4, a cathode 6 and the electrolyte material 1 is also disclosed.

Description

ELECTROLYTE MATERIAL WITH LiPON-COATED PARTICLES, BATTERY CELL,

AND METHOD FOR MANUFACTURING THE ELECTROLYTE MATERIAL

FIELD OF THE INVENTION

[0001] The invention relates to an electrolyte material for a battery cell, wherein the electrolyte material is present in a plurality of solid particles. The invention also relates to a battery cell using the electrolyte material as electrolyte. Another aspect of the invention relates to a method for manufacturing an electrolyte material.

BACKGROUND INFORMATION

[0002] In conventional lithium-ion battery cells with liquid electrolyte, lithium metal may build dendrites during repeated cycles of charging and discharging the battery cell. With an increased growth of the dendrites this may lead to short circuits within the cell, e.g. between anode and cathode, leading to a critical failure of the battery cell.

[0003] To prevent such failure due to short circuits, US 2016/211 567 A discloses a battery incorporating hybrid gel/solid electrolyte, comprising a lithium phosphorous oxynitride (LiPON) anode protector.

[0004] Such a coating of the anode may reduce the overall energy density of the battery cell due to its thickness. However, dendrites still lead to thermal runaway in this setup.

[0005] WO 191 213 40 Al discloses an electrolyte structure for a battery cell including a first portion configured as a thin film solid electrolyte and a second portion disposed adjacent to the first portion. The second portion includes a porous ceramic fiber material that contacts the electrolyte. The electrolyte structure is configured to be positioned between a positive electrode and a lithium metal negative electrode. The porous ceramic fiber material mechanically supports the electrolyte by strengthening it against internal and external stresses associated with fabrication and/or operation of the battery cell. The porous ceramic fiber material also provides a substrate on which the electrolyte is deposited, grown or otherwise formed.

[0006] Subject matter of current research are solid electrolytes with increased performance. For example, solid electrolytes made of sulfides or oxysulfides are high-performing, but suffer from poor chemical interface stability with lithium metal anodes.

[0007] It is the object of the present invention to provide a solid battery cell with increased chemical stability, in particular with respect to the solid electrolyte within the battery cell. This object is solved by an electrolyte material according to claim 1, a battery cell according to claim 7 as well as a method for manufacturing an electrolyte material according to claim 8. Non-trivial developments of the invention are subject matter of the dependent claims.

SUMMARY OF THE INVENTION

[0008] The present disclosure overcomes one or more shortcomings of the prior art and provides additional advantages. Embodiments and aspects of the disclosure described in detail herein are considered to be part of the claimed disclosure.

[0009] In one non-limiting embodiment of the present disclosure, an electrolyte material for a battery cell is described. The electrolyte material comprises a plurality of solid particles. According to the invention, each of the particles of the plurality comprises a respective coating with a lithium-based nitride. The lithium-based nitride may be lithium phosphorus oxynitride (LiPON), lithium silicon phosphorus oxynitride (LiSiPON) and/or lithium silicon phosphorus hydronitride (LiSiPHN). In other words, the electrolyte material is provided by the lithium-based-nitrid coated solid particles, or in parficalur the lithium phosphorous oxynitride-coated solid particles. Advantageously, each of the particles of the plurality is fully coated with the lithium-based nitride, or more particular the lithium phosphorous oxynitride. Alternatively or additionally at least some of the particles of the plurality are only partially covered with the lithium-based nitride, or more particular the lithium phosphorous oxynitride. In other words, each of the particles of the plurality is at least partially coated with lithium-based nitride, or more particular with lithium phosphorous oxynitride. In this context, at least partially coated" means that the respective particle is partially or fully coated.

[0010] The respective coating of the particles may be provided by a layer of lithium phosphorous oxynitride on a surface of the respective particle. Said layer may partially or fully cover the surface of the respective particle. In the present context, "solid' means that the particles are at least partially present in a solid phase. The term "solid phase" is therein to be understood in contrast to a gaseous or liquid phase. In some embodiments the electrolyte material is provided only by the lithium phosphorous oxynitride coated solid particles. In other embodiments, the electrolyte material may be supplemented by one or more additives. In other words, the electrolyte material may additionally comprise the one or more additives.

[0011] By the coating of the particles, stability issues of the particles in the context of a lithium-ion cell can be addressed. This is in particular the case when the particles of the plurality of particles are made of a solid sulfide compound or a solid oxysulfide compound. Said solid sulfide compound may for example be made of lithium, germanium, phosphorous, and sulfur. More particularly, the solid sulfide compound may be a so-called LOPS-type material. An example of LOPS-type materials is Li10GeP2S12. Alternatively or additionally, the solid sulfide compound may be argyrodite type sulfide electrolyte. As already mentioned, sulfide or oxysulfide electrolytes suffer from a poor chemical interface stability with the lithium metal anode material. Coating the particles with the lithium phosphorous oxynitride (LiPON) can solve this stability issue. If the coating or the layer of LiPON is thin enough, the performance of the particles with respect to its function as electrolyte is not affected. For example, the respective coating of each of the particles may have a thickness of less than 100 nanometer or less than 10 nanometer. In comparison, the particles of the plurality may each have a size between 1 micrometer and 1 centimeter, in particular between 1 micrometer and 1 millimeter. The coating of the particles may for example be provided by atomic layer deposition (ALD). The coating with atomic layer deposition results in a thin and continuous layer, in particular with a very constant thickness.

[0012] In one non-limiting embodiment of the present disclosure, a battery cell is described. The battery cell comprises an anode made of lithium and a cathode. Between the anode and the cathode the claimed electrolyte material is arranged. In other words, an electrolyte of the battery cell is provided by the electrolyte material. More particularly, the electrolyte of the battery cell may be provided by a plurality of solid particles. Each of the solid particles comprises a respective coating with lithium phosphorous oxynitride (LiPON). The electrolyte of the battery cell may additionally comprise other materials, e.g. one or more additives.

[0013] The present disclosure also claims a method for manufacturing an electrolyte material. The method comprises the following steps: in a first step, a plurality of solid particles is provided. In a second step, each of the particles is coated with lithium phosphorous oxide. According to a further development, the coating of the particles is performed by atomic layer deposition. In other words, the coating of the particles may take place in an atomic layer deposition process. Alternatively, of course, the coating can be carried out by any other suitable method.

[0014] From the method for manufacturing an electrolyte material a method for manufacturing a battery cell can be derived. Said method for manufacturing the battery cell may comprise additional steps compared to the method for manufacturing the electrolyte material. In a first one of the additional steps, an anode made of lithium and a cathode may be provided. In a second one of the additional steps, the lithium phosphorous oxynitride particles are arranged between the anode and the cathode.

[0015] All disclosed features of the electrolyte material equally apply to and are claimed for the battery cell, the method for manufacturing the electrolyte material, as well as the method for manufacturing the battery cell. In other words, all disclosed features within the scope of the present application are explicitly disclosed for each of the electrolyte material, the battery cell, and both methods for manufacturing.

[0016] Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawings. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respectively indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

[0017] The novel features and characteristics of the disclosure are set forth in the independent claims. The accompanying drawings, which are incorporated in and constitute part of this disclosure, illustrate exemplary embodiments and together with the description, serve to explain the disclosed principles. In the figures, the same reference signs are used throughout the figures to refer to identical features and components. Some embodiments of the system and/or methods in accordance with embodiments of the present subject-matter are now described in the following, by way of example only, and with reference to the accompanying figures.

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings show in: [0019] Fig. 1 an exemplary embodiment of a battery cell with an electrolyte material provided by a plurality of LiPON-coated particles; and [0020] Fig. 2 different steps of an exemplary method for manufacturing the battery cell.

[0021] In the figures same elements or elements having the same function are indicated by the same reference signs.

DETAILED DESCRIPTION

[0022] In the present document, the word "exemplary" is used herein to mean "serving as an example, instance, or illustration". Any embodiment or implementation of the present subject-matter described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0023] While the disclosure is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will be described in detail below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure.

[0024] The terms "comprises", "comprising", "include(s)", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, system or method that comprises a list of components or steps does not include only those components or steps but may include other components or steps not expressly listed or inherent to such setup or system or method. In other words, one or more elements in a system or apparatus preceded by "comprises" or "comprise" does not or do not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

[0025] In the following detailed description of the embodiments of the disclosure, reference is made to the accompanying drawings that form a part hereof, and in which are shown by way of illustration specific embodiments in which the disclosure may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present disclosure. The following description is, therefore, not to be taken in a limiting sense.

[0026] The present disclosure will be described herein in the following with reference to the accompanying drawings. In the following description, well-known functions or details are not described in detail since they would obscure the description with unnecessary detail.

[0027] Fig. 1 shows an exemplary embodiment of a battery cell 2. The battery cell 2 is configured for usage in a battery for providing electrical power. Such a battery may comprise one or more battery cells 2. The battery cells 2 of a battery may be connected in electrically conductive manner. The battery cells 2 may for example be connected in series and/or in parallel. In a common embodiment, several battery cells 2 are connected in series forming a group, wherein several groups are connected in parallel. The battery can for example be used in a motor vehicle, in particular to provide electrical power for driving the vehicle. In other words, the battery may be configured to supply an electric engine of the vehicle with electrical power for driving the vehicle.

[0028] Referring again to Fig. 1, the battery cell 2 comprises an anode and a cathode. The anode comprises a current collector 3 and a lithium metal anode 4. In other words, the current collector 3 and the lithium metal anode 4 together form the anode of the battery cell 2. The current collector 3 is made of copper in the present case. The cathode comprises a current collector 5 and a cathode electrolyte mixture 6. In other words, the current collector 5 and the cathode electrolyte mixture 6 together form the cathode of the battery cell 2 in the present embodiment. The current collector 5 is made of aluminium in the present embodiment.

[0029] In between the anode and the cathode, or more specifically in between the lithium anode 4 and the cathode electrolyte mixture 6, an electrolyte 1 is arranged. In other words, the electrolyte 1 made of electrolyte material is arranged between the anode and the cathode of the battery cell 2.

[0030] The electrolyte material forming the electrolyte 1 comprises a plurality of solid particles 7. The solid particles 7 may be present in a solid phase, in contrast to a gaseous or liquid phase. In general, the particles 7 may be formed from any sulfide material. Advantageous representatives of the class of sulfides are oxysulfides, LOPS type sulfides and argyrodite type sulfides. Materials form the class of oxysulfides may generally have particularly good properties for forming the particles 7 of the electrolyte material. The oxysulfide solid particles 7, for example, may contain an oxysulfide-based solid electrolyte represented by compositional formula Li4-x[M'kM"1-d1-xPxS4_z0z, where M' is comprised of Si, Ge, Sn, As, Se, Te, Cl, Br, I, Al, and M" is comprised of Si, Ge, Sn, As, Se, Te Cl, Br, I, Al, where 0.33 5 x 5 0.65, where 0.0 5 k 5 0.5, and 0.0 z a. 1.0. Additionally or alternatively, the solid particles 7 may contain a LOPS type sulfide-based solid electrolyte represented by compositional formula Li m.-:1-P s where M' is comprised of Si, Ge, Sn, xx* x-4, As, Se, Te Cl, Br, I, or Al, where 0.33 5 x 5 0.65, where 0.1 5 k 50.5, and 0.1 z 1.0. Additionally or alternatively, the solid particles 7 may contain an argyrodite type sulfide-based solid electrolyte represented by compositional formula Li7,2yPS6,y M'x, where M' is comprised of Cl, Br, or I and where 0.8 x1.7 and 0<y-0.25x+0.5.

[0031] In the present embodiment, the particles 7 are made of a solid sulfide compound or a solid oxysulfide compound. In other words, the particles 7 may be formed from the solid sulfide material or the solid oxysulfide material. Sulfide compounds consisting of lithium, germanium, phosphorous, and sulfur have proven to impart very advantageous properties to the electrolyte material. So in a very advantageous embodiment, the particles 7 are made of lithium, germanium, phosphorous, and sulfur. These sulfide materials are also known as LOPS-type sulfide materials. These LOPS-type sulfide materials have some of the highest conductivity of any electrolyte material. A drawback of said sulfide materials is their instability in contact with lithium metal. This may lead to degradation due to the adjacent lithium anode 4. For example, the particles 7 can be made of Li10GeP2S12, which is an example of the above-mentioned LOPS-type sulfide materials.

B

[0032] To prevent this type of degradation, the particles 7 are each at least partially coated with a lithium-based nitride B. In the present embodiment, the lithium-based nitride 8 is lithium phosphorous oxynitride 8 (LiPON 8). Addiotionally or alternatilvely the lithium-based nitride may be provided by lithium silicon phosphorus oxynitride (LiSiPON) and/or lithium silicon phosphorus hydronitride (LiSiPHN).

[0033] The particles 7 comprise a thin layer of LiPON 8 on their surface. In the present embodiment, the particles 7 are fully coated with LiPON 8. In other words, the complete surface of the particles 7 is covered with the layer of LiPON 8. In other embodiments, it is possible that at least some particles 7 are not fully coated with LiPON 8. If this is the case, the surface of at least some of the particles 7 is not completely covered with the layer of LiPON B. For example, the coating of the particles 7 with LiPON 8 is characterized by features derived by atomic layer deposition as a coating mechanism. In other words, the coating of the particles 7 with LiPON 8 can be provided by atomic layer deposition. LiPON may for example have the chemical formula Li2P02N. In the present embodiment, the lithium phosphorus oxynitride forming the coating of the particles is represented by compositional formula Li2SibP0cHdNe, where: 2a6, (Li); 0<=b<=2, (Si); 2c6, (0); 0<=d<=2, (H); and 0 (N). In the present embodiment, with a polymer pre-cursor based LiPON material, it is possible to achieve up to 6 parts lithium and 1.7 parts nitrogen. A ratio of oxygen to phosphorous may be at least 2.

[0034] The coating by atom layer deposition results in a very thin and even coating of the particles 7. By the resulting thin coating it is further ensured that the LiPON 8 coating does not affect the performance of the electrolyte 1 or the electrolyte material, respectively. By contrast, thick layers of LiPON 8 affect the performance of the electrolyte 1 or the electrolyte material, respectively, due to the space consumption of the LiPON 8 coating. In particular, the coating of the particles 7 with LiPON 8 may have a thickness of at least 100 nanometers or preferably at least 10 nanometers. Such a thickness is achievable by atomic layer deposition. A coating which is as thin as the one mentioned in the above does not affect the performance of the electrolyte 1 or the electrolyte material, respectively, or affects the performance only to a neglectable extent. By way of decoating it is possible to utilize the great conductivity and processability of the sulfide or oxysulfide compound materials as electrolyte 1. On the other hand, the usability within the scope of lithium cells comprising a lithium anode 4 is improved.

[0035] Referring now to Fig. 2, different steps of manufacturing the battery cell 2 are shown. In a first step Si a plurality of the particles 7 is provided. In a second step S2 the particles 7 are coated with LiPON 8 by atomic layer deposition. In other words, in step 52 an atomic layer deposition process is used for coating the particles 7 with LiPON 8. Steps Si and 52 together may form an exemplary procedure for manufacturing an electrolyte 1 or an electrolyte material, respectively.

[0036] By an additional step S3 the exemplary method for manufacturing the battery cell 2 is created. In the additional step S3, the electrolyte material, in particular the LiPONcoated particles 7, are arranged between an anode and a cathode.

[0037] It should be appreciated that other coating processes may be used for coating the particles 7 with LiPON 8 in step S2. The coating of the particles 7 by the atomic layer deposition process is therefore to be understood as a non-limiting example.

List of reference signs 1 electrolyte material 2 battery cell 3 current collector 4 lithium metal anode current collector 6 electrolyte mixture 7 particles 8 UPON

Claims

CLAIMS1. An electrolyte material for a battery cell, wherein the electrolyte material is provided by a plurality of solid particles, characterized in that each of the particles comprises a respective coating with lithium-based nitride.
2. The electrolyte material according to claim 1, characterized in that the lithium-based nitride forming the coating of the particles is represented by compositional formula LiaSibPO,HdNe, where: 2a6, (Li); 0<=b<=2, (Si); 2c6, (0); 0<=d<=2, (H); and 0e2, (N).
3. The electrolyte material according to claim 1 or 2, characterized in that the lithium-based nitride is formed by lithium phosphorus oxynitride (LiPON), lithium silicon phosphorus oxynitride (LiSiPON) and/or lithium silicon phosphorus hydronitride (LiSiPHN).
4. The electrolyte material according to any one of claims 1 to 3, characterized in that the particles of the plurality are made of a solid sulfide compound or a solid oxysulfide compound.
5. The electrolyte material according to claim 4, characterized in that the solid sulfide compound is made of lithium, germanium, phosphorus, and sulfur.
6. The electrolyte material according to any one of claims 1 to 5, characterized in that the particles of the plurality each have a size between lpm and 1mm.
7. The electrolyte material according to any one of claims 1 to 6, characterized in that the respective coating of the particles have a thickness of less than 100nm or less than 10nm.
8. The electrolyte material according to any one of claims 1 to 7, characterized in that the respective coating of the particles is provided by atomic layer deposition.
9. A battery cell comprising: - an anode made of lithium, - a cathode, and - the electrolyte material according to any one of claims 1 to 8, which is arranged between the anode and the cathode.
10. A method for manufacturing an electrolyte material, the method comprising the following steps: - providing a plurality of solid particles; and - coating each of the particles with a lithium-based nitride.
11. The method according to claim 10, characterized in that the coating of the particles is performed by atomic layer deposition.