SIC SEPARATOR AND SIC CELL

Abstract

A separator and/or protective layer for a lithium cell. In order to enable rapid charging of the cell and to extend the service life of the cell, the separator and/or the protective layer encompasses a copolymer and/or a polymer blend, the copolymer encompassing at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing repeating unit, and/or the polymer blend encompassing at least one polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing polymer. Cells, and copolymers, polymer blends, and polymer electrolytes on the basis of polymers having a lithium-ion transference number >0.7, are also described.

Claims

1-20. (canceled)

21. A separator and/or protective layer for a lithium cell, comprising: at least one of: (i) a copolymer encompassing at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing repeating unit, and (ii) a polymer blend encompassing at least one polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing polymer.

22. The separator and/or protective layer as recited in claim 21, wherein at least one of: (i) the at least one mechanically stabilizing repeating unit encompasses at least one styrene-based repeating unit, and (ii) the at least one mechanically stabilizing polymer encompasses at least one styrene-based polymer.

23. The separator and/or protective layer as recited in claim 1, wherein at least one of: (i) the at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7 is designed to constitute a single-ion-conducting polyelectrolyte, and (ii) the at least one polymer having a lithium-ion transference number >0.7 encompasses a single-ion-conducting polyelectrolyte.

24. The separator and/or protective layer as recited in claim 23, wherein one of: (i) the at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7, or (ii) the at least one repeating unit for constituting a single-ion-conducting polyelectrolyte, encompasses at least one of a borate-based unit, a sulfonic acid-based unit, a sulfonylimide-based unit, a unit based on lithiated acrylic acid, and a unit based on methacrylic acid.

25. The separator and/or protective layer as recited in claim 23, wherein one of: (i) the at least one polymer having a lithium-ion transference number >0.7, or (ii) the at least one single-ion-conducting polyelectrolyte, encompasses at least one of a borate-based polyelectrolyte, a sulfonic acid-based polyelectrolyte, a sulfonylimide-based polyelectrolyte, a polyelectrolyte based on lithiated acrylic acid, a polyelectrolyte based on methacrylic acid.

26. The separator and/or protective layer as recited in claim 21, wherein the copolymer is a block copolymer, the block copolymer encompassing at least one block made of at least one repeating unit for constituting a single-ion-conducting polyelectrolyte, and at least one block made of at least one mechanically stabilizing styrene-based, repeating unit.

27. The separator and/or protective layer as recited in claim 21, wherein at least one of: (i) the copolymer encompasses at least one lithium-ion-conductive repeating unit, and (ii) the polymer blend encompasses at least one lithium-ion-conductive polymer.

28. The separator and/or protective layer as recited in claim 27, wherein the at least one lithium-ion-conductive repeating unit is at least one of an ethylene oxide unit, an oligoethylene glycol methacrylate unit, and an oligoethylene glycol methacrylate unit.

29. The The separator and/or protective layer as recited in claim 27, wherein the at least one lithium-ion-conductive polymer is at least one of polyethylene oxide, poly(oligoethylene glycol) methacrylate, and poly(oligoethylene glycol) methacrylate.

30. The separator and/or protective layer as recited in claim 26, wherein the block copolymer is one of a di-block copolymer, a tri-block copolymer, or multi-block copolymer.

31. The separator and/or protective layer as recited in claim 21, wherein the separator and/or the protective layer furthermore encompasses at least one inorganic single-ion conductor, the at least one inorganic single-ion conductor being at least one of a lithium argyrodite, and a sulfidic glass.

32. A lithium cell, comprising: a separator and/or a protective layer including at least one of: (i) a copolymer encompassing at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing repeating unit, and (ii) a polymer blend encompassing at least one polymer having a lithium-ion transference number >0.7 and at least one mechanically stabilizing polymer.

33. A lithium cell, comprising: a cathode; an anode; and a separator and/or a protective layer disposed between the cathode and the anode, the separator and/or the protective layer encompassing at least one of: (i) at least one polymer having a lithium-ion transference number >0.7, and (ii) at least one ceramic and/or glass-like, inorganic single-ion conductor having a lithium-ion transference number >0.7; wherein at least one of: (A) the cathode encompasses at least one of: (i) at least one polymer having a lithium-ion transference number >0.7, and (ii) at least one ceramic and/or glass-like, inorganic single-ion conductor, and (B) the anode encompasses at least one of (i) polymer having a lithium-ion transference number >0.7 and (ii) at least one ceramic and/or glass-like, inorganic single-ion conductor.

34. The lithium cell as recited in claim 33, wherein at least one of: (i) the at least one inorganic single-ion conductor of the separator and/or of the protective layer is at least one of a lithium argyrodite, and a sulfidic glass, (ii) the at least one inorganic single-ion conductor of the cathode is at least one of a lithium argyrodite, a sulfidic glass, and (iii) the at least one inorganic single-ion conductor of the anode being at least one of a lithium argyrodite and a sulfidic glass.

35. The lithium cell as recited in claim 34, wherein the at least one polymer, having a lithium-ion transference number >0.7, of the separator and/or of the protective layer encompasses a single-ion-conducting polyelectrolyte, and wherein at least one of: (i) the at least one polymer, having a lithium-ion transference number >0.7 of the cathode encompasses a single-ion-conducting polyelectrolyte, and (ii) the at least one polymer, having a lithium-ion transference number >0.7 of the anode encompasses a single-ion-conducting polyelectrolyte.

36. The lithium cell as recited in claim 35, wherein the at least one polymer having a lithium-ion transference number >0.7 or the at least one single-ion-conducting polyelectrolyte, of the separator and/or of the protective layer encompasses at least one of a borate-based polyelectrolyte, a sulfonic acid-based polyelectrolyte, a sulfonylimide-based polyelectrolyte, a polyelectrolyte based on lithiated acrylic acid, and a polyelectrolyte based on methacrylic acid, and wherein at least one of: (i) the at least one polymer, having a lithium-ion transference number >0.7, or the at least one single-ion-conducting polyelectrolyte, of the cathode encompasses one of a borate-based polyelectrolyte, a sulfonic acid-based polyelectrolyte, a sulfonylimide-based polyelectrolyte, a polyelectrolyte based on lithiated acrylic acid, and a polyelectrolyte based on methacrylic acid, and (ii) the at least one polymer having a lithium-ion transference number >0.7, or the at least one single-ion-conducting polyelectrolyte, of the anode encompasses at least one of a borate-based polyelectrolyte, a sulfonic acid-based polyelectrolyte. a sulfonylimide-based polyelectrolyte, a polyelectrolyte based on lithiated acrylic acid, and a polyelectrolyte based on methacrylic acid.

37. The lithium cell as recited in claim 33, wherein the separator and/or the protective layer encompasses a blend of at least one polymer having a lithium-ion transference number >0.7, the blend of the separator and/or protective layer including a single-ion-conducting polyelectrolyte, and at least one inorganic ion conductor, the at least one inorganic ion conductor including at least one of a lithium argyrodite and a sulfidic glass; and wherein at least one of: (i) the cathode encompasses a blend of at least one polymer having a lithium-ion transference number >0.7, the blend of the cathode including a single-ion-conducting polyelectrolyte, and at least one inorganic ion conductor, the at least one inorganic ion conductor including at least one of a lithium argyrodite and a sulfidic glass, and (ii) the anode encompasses a blend of at least one polymer having a lithium-ion transference number >0.7, the blend of the anode including at least one of a single-ion-conducting polyelectrolyte, and at least one inorganic ion conductor, the at least one inorganic ion conductor including at least one of a lithium argyrodite and a sulfidic glass.

38. The lithium cell as recited in claim 33, wherein one of: (i) the anode is a lithium metal anode, and the separator and/or the protective layer and the cathode encompass at least one single-ion-conducting polyelectrolyte, or (ii) the anode encompasses a particulate anode active material, and the separator and/or the protective layer, the cathode, and the anode encompass at least one single-ion-conducting polyelectrolyte.

39. A copolymer, the copolymer encompassing at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7, the at least one repeating unit including at least one of: a borate-based unit, a sulfonic acid-based unit, a sulfonylimide-based unit, a unit based on lithiated acrylic acid, a unit based on methacrylic acid, and a perfluoroether-based unit, and at least one styrene-based repeating unit.

40. A polymer blend, the polymer blend encompassing at least one polymer having a lithium-ion transference number >0.7, the at least one polymer including at least one of a borate-based polyelectrolyte, a sulfonic acid-based polyelectrolyte, a sulfonylimide-based polyelectrolyte, a polyelectrolyte based on lithiated acrylic acid, a polyelectrolyte based methacrylic acid, and a perfluoroether-based polymer, and at least one styrene-based polymer.

41. The copolymer as recited in claim 39, wherein the copolymer is a block copolymer, the block copolymer encompassing at least one block made of at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7 and at least one block made of at least one styrene-based, repeating unit.

42. The copolymer as recited in claim 39, wherein the copolymer further encompasses at least one lithium-ion-conductive repeating unit, the at least one lithium-ion-conductive repeating unit being at least one of an alkylene oxide unit, an ethylene oxide unit, an oligoethylene glycol methacrylate unit, and an oligoethylene glycol acrylate unit.

43. The polymer blend as recited in claim 40, wherein the polymer blend further encompasses at least one lithium-ion-conductive polymer, the at least one lithium-ion-conductive polymer encompassing at least one of polyethylene oxide, poly(oligoethylene glycol) methacrylate, and poly(oligoethylene glycol) acrylate.

44. The copolymer as recited in claim 41, wherein the block copolymer further encompasses at least one block made of at least one lithium-ion-conductive repeating unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0151] Further advantages and advantageous embodiments of the present invention are illustrated in the figures and explained in the description below. Be it noted in this context that the figures are merely descriptive in nature and are not intended to limit the present invention in any way.

[0152] FIG. 1 is a schematic cross section through an embodiment of a lithium cell according to the present invention.

[0153] FIG. 2 is a graph to illustrate the dependence between a minimally required transference number (t.sup.+.sub.min) for a cathodic polymer electrolyte in the context of an assumed ionic conductivity or diffusion coefficient of the cathodic polymer electrolyte in a cell in order to achieve a 1C, 2C, and 3C rate capability for the cell.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0154] FIG. 1 shows a lithium cell 1, in particular in the form of a solid-state cell, which encompasses a cathode 2 and an anode 3, a separator 4 being disposed between cathode 2 and anode 3. Anode 3 is a lithium metal anode made of metallic lithium. Separator 4 also performs the function of a protective layer with respect to dendrite formation from anode 3.

[0155] Separator 4 encompasses in particular at least one polymer having a lithium-ion transference number >0.7. Separator 4 can in particular encompass for that purpose at least one single-ion-conducting polyelectrolyte. For instance, separator 4 can encompass a borate-based polyelectrolyte and/or a sulfonic acid-based polyelectrolyte and/or an imide-based, in particular sulfonylimide-based, polyelectrolyte, and/or a polyelectrolyte on the basis of lithiated acrylic acid and/or methacrylic acid. Separator 4 can furthermore encompass at least one, in particular ceramic and/or glass-like, inorganic ion conductor, in particular single-ion conductor, having a lithium-ion transference number >0.7, for example a lithium argyrodite and/or a sulfidic glass (not depicted).

[0156] Cathode 2 encompasses an, in particular particulate, cathode active material 5, for example based on metal oxide such as nickel cobalt aluminum oxide (NCA), nickel cobalt manganese oxide (NCM), high-energy nickel cobalt manganese oxide (HE-NCM), lithium manganese oxide (LMO), and/or high-voltage spinels (HV-LMO), and/or based on sulfur, and, in particular constituting catholyte 6, at least one polymer having a lithium-ion transference number >0.7 and/or at least one, in particular ceramic and/or glass-like, inorganic ion conductor, in particular single-ion conductor, having a lithium-ion transference number >0.7. Cathode 2 can in particular encompass for this purpose at least one single-ion-conducting polyelectrolyte and/or at least one lithium argyrodite and/or sulfidic glass. For instance, cathode 2 can encompass a borate-based polyelectrolyte and/or a sulfonic acid-based polyelectrolyte and/or an imide-based, in particular sulfonylimide-based, polyelectrolyte, and/or a polyelectrolyte on the basis of lithiated acrylic acid and/or methacrylic acid. Cathode 2 furthermore encompasses a conduction additive 7, for example carbon black and/or graphite, to improve the electrical conductivity of cathode 2.

[0157] The at least one polymer having a lithium-ion transference number >0.7, in particular the at least one single-ion-conducting polyelectrolyte, of separator 4, and the at least one polymer having a lithium-ion transference number >0.7, in particular the at least one single-ion-conducting polyelectrolyte, of cathode 2 can be different or, if applicable, also at least similar.

[0158] FIG. 1 furthermore shows that cathode 2 is equipped with a current collector 8.

[0159] In the context of a special example embodiment, separator 4 encompasses a copolymer and/or a polymer blend, the copolymer encompassing at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7, in particular for constituting a single-ion-conducting polyelectrolyte, and at least one mechanically stabilizing repeating unit, and/or the polymer blend, encompassing at least one polymer having a lithium-ion transference number >0.7, in particular at least one single-ion-conducting polyelectrolyte, and at least one mechanically stabilizing polymer. The at least one mechanically stabilizing repeating unit can encompass or be at least one styrene-based repeating unit, and/or the at least one mechanically stabilizing polymer can encompass or be at least one styrene-based polymer. In particular, the at least one polymer having a lithium-ion transference number >0.7 of separator 4 and the at least one polymer having a lithium-ion transference number >0.7 of cathode 2 can differ from one another at least in that the at least one polymer having a lithium-ion transference number >0.7 of cathode 2 is devoid of a mechanically stabilizing, for example styrene-based, repeating unit, and/or devoid of a mechanically stabilizing, in particular styrene-based, polymer. The at least one repeating unit for constituting a polymer having a lithium-ion transference number >0.7, and/or the at least one polymer having a lithium-ion transference number >0.7, of separator 4, and the at least one polymer having a lithium-ion transference number >0.7 of cathode 2, can otherwise likewise be different or, in particular, can also be at least similar to one another or, if applicable, can even be identical.

[0160] FIG. 2 illustrates the results of calculations in which the minimally required lithium-ion transference numbers t.sup.+.sub.min, required in order to implement a charging operation at a constant C rate SOC=0% to SOC=75%, of a cathodic polymer electrolyte having an assumed conductivity or diffusion coefficient for a cell have been calculated. The basis here was a cell having a 10-m thick separator which, constituting a conventional polymer electrolyte, for instance PEO/LiTFSI, is embodied with a conductivity of 4 e.sup.4 S/cm, a salt diffusion coefficient of 1 e.sup.12 m.sup.2/s, and a lithium-ion transference number t.sup.+ of 0.25, and whose transport properties are not varied, and having a cathode that has a charge of 4 mAh/cm.sup.2 and likewise contains a polymer electrolyte, for instance PEO/LiTFSI, whose transport properties have, however, been varied. The transport properties of the polymer electrolyte of the cathode which were varied were in particular the conductivity I and the diffusion coefficient D of a conducting salt in the polymer electrolyte of the cathode.

[0161] FIG. 2 depicts the results for simulated charging operations at a constant C rate, namely for 1C in curve 10, for 2C in curve 11, and for 3C in curve 12. In FIG. 2, curve 12 at approximately 1 e.sup.2 S/cm can be interpreted to mean that for a constant current charge 3C, a transference number t.sup.+>0.5 is required. What was used for calculation of the graph depicted in FIG. 2, however, was a PEO-based polymer electrolyte, having a lithium-ion transference number t.sup.+ of 0.25, as a separator, which results in an additional concentration polarization and thus increases the demand in terms of the transference number of the polymer electrolyte of the cathode (catholyte). When a polymer having a lithium-ion transference number >0.7, and in particular a single-ion-conducting polyelectrolyte, for example having a lithium-ion transference number >0.8 or >0.9, is used as a separator and/or protective layer, the demands in terms of the minimally required lithium-ion transference numbers of the catholyte advantageously decrease as compared with what is depicted in FIG. 2. It is thus apparent, advantageously, that, for instance, a 3C charging operation can already be achieved with a catholyte conductivity of 1 e.sup.3 S/cm and a lithium-ion transference number >0.7, for instance already for a lithium-ion transference number t.sup.+=0.5, in the catholyte (not depicted in the Figures).