Abstract
The present invention relates to an electrode material for an electrochemical energy accumulator, in particular for a lithium-ion cell, comprising particles (10, 10, 10) of an active material (12) which can be lithiated, wherein the particles (10, 10, 10) are partially coated with a lithium-ion-conducting solid electrolyte (14), the solid electrolyte layer (14) having recesses (16).
Claims
1. An electrode material for an electrochemical energy store, comprising particles (10, 10, 10) of a lithiatable active material (12), where the particles (10, 10, 10) are partly coated with a lithium-ion-conducting solid electrolyte layer (14), characterized in that the solid electrolyte layer (14) has recesses (16).
2. The electrode material as claimed in claim 1, characterized in that a width (B) of the recesses (16) in the solid electrolyte layer (14) is in the range from 10 nm to 800 nm.
3. The electrode material as claimed in claim 1, characterized in that a thickness (D) of the solid electrolyte layer (14) is in the range from 20 nm to 500 nm.
4. The electrode material as claimed in claim 1, characterized in that the recesses (16) or the recesses (16) and the solid electrolyte layer (14) are at least partly covered or coated with an electronically conductive material (18).
5. The electrode material as claimed in claim 4, characterized in that the electronically conductive material (18) is composed of carbon.
6. The electrode material as claimed in claim 1, characterized in that the recesses (16) or the recesses (16) and the solid electrolyte layer (14) are at least partly covered or coated with a mixture of an electronically conductive material (18) and a lithium-ion-conducting material (20).
7. The electrode material as claimed in claim 1, characterized in that the coated particles (10, 10, 10) are embedded in a matrix (22) comprising a lithium-ion-conducting material.
8. The electrode material as claimed in claim 1, characterized in that the coated particles (10) are embedded in a matrix (22) composed of a composite material comprising a lithium-ion-conducting material and electronically conductive material.
9. An electrode, comprising at least one electrode material as claimed in claim 1.
10. An electrochemical energy store, comprising an electrode as claimed in claim 9.
11. The electrode material as claimed in claim 4, characterized in that the electronically conductive material (18) is selected from among carbon black, graphite or carbon nanotubes.
12. A cathode, comprising at least one electrode material as claimed in claim 1.
13. A lithium ion cell, comprising an electrode as claimed in claim 9.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Further advantages and advantageous embodiments of the subject matter of the invention are illustrated by the drawings and explained in the following description, with the features described being able to form subject matter of the present invention individually or in any combination, unless the contrary is clear from the context. It should be noted here that the drawings have only descriptive character and are not intended to restrict the invention in any way. The drawings show
[0040] FIG. 1a) a schematic view of a particle according to a first working example of the electrode material of the invention;
[0041] FIG. 1b) an enlargement of a section from FIG. 1a) in sectional view;
[0042] FIG. 1c) a schematic view of a further particle according to the first working example of the electrode material of the invention;
[0043] FIG. 2a) a schematic view of a particle partly coated with an electronically conductive material;
[0044] FIG. 2b) an enlargement of a section of FIG. 2a) in sectional view;
[0045] FIG. 2c) a schematic view of two further adjacent particles which are coated with an electronically conductive material;
[0046] FIG. 3a) a schematic view of a particle partly coated with an electronically and ionically conductive material;
[0047] FIG. 3b) an enlargement of a section of FIG. 3a) in sectional view;
[0048] FIG. 3c) a schematic view of two further adjacent particles which are coated with an electronically and ionically conductive material;
[0049] FIG. 4 a schematic view of particles which are embedded in a matrix.
DETAILED DESCRIPTION
[0050] FIG. 1a) depicts a particle 10 composed of a lithiatable active material 12. The active material 12 can be a cathode material, in particular a lithium-containing transition metal oxide such as lithium-cobalt oxide or lithium-cobalt oxide in which part of the cobalt has been replaced by manganese, nickel and/or aluminum. The active material can, in particular, be a lithium-nickel-manganese-cobalt oxide such as LiNi.sub.0.8Co.sub.0.1Mn.sub.0.1O.sub.2(NCM 8-1-1) or LiNi.sub.0.6Co.sub.0.2Mn.sub.0.2O.sub.2 (NCM 6-2-2). The particle 10 is partly coated with a lithium-ion-conducting solid electrolyte 14. The lithium-ion-conducting solid electrolyte can be a lithium phosphoroxynitride (LiPON), a garnet of the general formula Li.sub.yA.sub.3B.sub.2O.sub.12, a perovskite of the general formula Li.sub.3xLa.sub.2/3-xTiO.sub.3, a compound of the NASICON type, a lithium-ion-conducting sulfidic glass or an argyrodite of the formula Li.sub.6PS.sub.5X. In particular, the lithium-ion-conducting solid electrolyte can be composed of a lithium-lanthanum titanate (LLTO). The solid electrolyte layer 14 has recesses 16. The recesses 16 are, in particular, crack-like.
[0051] FIG. 1b) shows an enlargement of a section of FIG. 1a) in sectional view. As is depicted in this view, the width (B) of the recesses 16 can be in the range from 10 nm to 800 nm. For example, the width can be about 100 nm. The thickness (D) of the solid electrolyte layer 14 can be in the range from 20 nm to 500 nm.
[0052] FIG. 1c) shows a schematic three-dimensional view of a further particle which is composed of a lithiatable active material 12 and is partly coated with a lithium-ion-conducting solid electrolyte 14. The recesses on the rear side of the particle are indicated by broken lines.
[0053] FIG. 2a) depicts a particle 10 which is composed of a lithiatable active material 12 and is partly coated with a lithium-ion-conducting solid electrolyte 14. The solid electrolyte layer 14 has in particular crack-like recesses 16. In this embodiment, the recesses 16 and the solid electrolyte layer 14 are partly coated with an electronically conductive material 18. In particular, the regions of the solid electrolyte layer 14 which adjoin the recesses 16 are covered with the electronically conductive material 18. The electronically conductive material 18 can be composed of carbon, in particular conductive carbon black, graphite or carbon nanotubes. The enlarged sectional view of FIG. 2b) shows that the recess 16 of the solid electrolyte layer 14 is filled with the electronically conductive material 18 while the adjoining surface of the solid electrolyte layer 14 is likewise covered with the electronically conductive material 18. The conductive material can likewise be present in pores or crevices of the solid electrolyte.
[0054] FIG. 2c) shows two neighboring particles 10 and 10 which are each covered with an electronically conductive material 18. Here, it is possible, as shown in FIG. 2c), for the volume between the particles 10 and 10 to be filled with the electronically conductive material 18.
[0055] FIG. 3a) depicts a particle 10 which is composed of a lithiatable active material 12 and is partly coated with a lithium-ion-conducting solid electrolyte 14, with the solid electrolyte layer 14 having in particular crack-like recesses 16. The recesses 16 and the solid electrolyte layer 14 are, in this embodiment, partly coated with a mixture of an electronically conductive material 18 and a lithium-ion-conducting material 20. The electronically conductive material 18 can be made up of carbon particles such as carbon black. The lithium-ion-conducting material 20, or the particles of the lithium-ion-conducting material, can be, in particular, composed of lithium-ion-conducting sulfidic glasses or argyrodites of the formula Li.sub.6PS.sub.5X. The particles of the lithium-ion-conducting material 20 preferably correspond to the material of the solid electrolyte layer 14.
[0056] The enlarged sectional view of FIG. 3b) shows that the recess 16 of the solid electrolyte layer 14 is filled with the particles of the electronically conductive material 18 and the lithium-ion-conducting material 20, while the adjoining surface of the solid electrolyte layer 14 is likewise covered thereby. The electronically conductive and lithium-ion-conducting material can likewise penetrate into pores or crevices of the solid electrolyte 14. FIG. 3c) shows two neighboring particles 10 and 10 which are each covered with electronically conductive material 18 and the lithium-ion-conducting material 20. Here, it is possible, as shown in FIG. 3c), for the volume between the particles 10 and 10 to be filled with the electronically conductive material 18 and the lithium-ion-conducting material 20.
[0057] FIG. 4 shows particles 10 which are embedded in a matrix 22 comprising a lithium-ion-conducting material. The particles are coated with a lithium-ion-conducting solid electrolyte 14 and the recesses 16 are filled with an electronically conductive material 18. The particles can have a size of from 0.1 m to 10 m, for example from 1 m to 3 m. The matrix can comprise a polymer material or a glass-ceramic and a lithium salt. In some embodiments, the matrix 22 can be composed of a polymer based on polyethylene oxide (PEO) containing a lithium salt such as LiPF.sub.6, LiBF.sub.4, LiSbF.sub.6, LiAsF.sub.6, LiTFSI, LiClO.sub.4, LiBOB or LiDFOB. The matrix 22 particularly preferably comprises PEO and LiTFSI. In other embodiments, the particles can be embedded in a matrix 22 composed of a composite material comprising a lithium-ion-conducting material and an electronically conductive material. In these embodiments, the matrix can additionally contain an electronically conductive additive such as conductive carbon black or graphite, in particular carbon black.
