Anionic redox high energy cathodes

Abstract

A composition useful from making cathodes for use in lithium ion rechargeable batteries is comprised of an alloy of a lithium borate and a lithium metal oxide, wherein the metal is one or more of Co, Mn and Ni. The alloy may have other lithium salts such as lithium sulfate and lithium phosphate. The alloys may be useful in lithium ion batteries having solid electrolytes.

Description

ANIONIC REDOX HIGH ENERGY CATHODESCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This is a PCT International application which claims priority to U.S. Provisional Patent Application Number 63 / 556,154 filed on February 21, 2024, which is incorporated herein by reference in their entirety for all purposes.TECHNICAL FIELD

[0002] This disclosure relates to anionic redox high energy cathodes.BACKGROUND

[0003] Lithium ion batteries over the last three decades have become common place in the market. Initially, Co based oxide batteries first became commercially employed in portable electronics. With the advent of electrification of transportation vehicles, layered oxide materials containing Co, Mn and Ni have become more prevalent for batteries requiring liquid electrolytes due to the low electrical conductivity. Even with these materials, the energy density is desired to be improved to allow for greater range of all electric vehicles as well as the reduction of the use of Ni and Co and for safety reasons the use of solid state batteries.

[0004] More recently, excess lithium materials such as disordered oxide rock salt materials have been reported taking advantage of excess lithium content in oxides have metal compensating metal ions such as Nb, V, Zr and Mo. These have tended to have similar limitations as the layered oxide materials.

[0005] Accordingly, it would be desirable to provide a lithium battery cathode that improves energy density, reversible capacity and electrical conductivity for batteries including solid state batteries.SUMMARY

[0006] It has been discovered that lithium borate may be alloyed with a lithium metal oxide where the metal is Co, Mn, Ni or combination thereof. Alloy means the crystallography of the alloy is distinct from each of the alloy constituents. The inclusion of the borate salt may increase the initial capacity of the cathode. Further lithium salts may be blended with the lithium borate salt such as lithium sulfate and lithium phosphate to realizedesired balance of properties (e.g., cycle life, rate performance, capacity, energy density and the like).BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosure is best understood from the following detailed description when read in conjunction with the accompanying drawings. It is emphasized that, according to common practice, the various features of the drawings are not to-scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity.

[0008] FIG. 1 shows the capacity of batteries comprised of Co, Mn and Ni oxides alloyed with and without borate cathodes at two differing cycle rates.

[0009] FIG. 2 shows the capacity of batteries having cathodes comprised of Co oxide alloys with and without lithium borate at two differing cycle rates.

[0010] FIG. 3 shows capacity of batteries having cathodes comprised of Co oxide alloyed with and without lithium borate after 20 charge / discharge cycles.

[0011] FIG. 4 shows the initial and subsequent capacity of batteries having cathodes comprised of Mn oxide alloys with and without lithium borate.

[0012] FIG. 5 shows the capacity of batteries having cathodes comprised of Mn oxide alloys with and without lithium borate at two differing cycle rates.

[0013] FIG. 6 shows the initial and subsequent capacity of batteries having cathodes comprised of Ni oxide alloys with and without lithium borate.

[0014] FIG. 7 shows the capacity of batteries having cathodes comprised of Ni oxide alloys with and without lithium borate at two differing cycle rates.

[0015] FIG. 8 shows the X-ray powder diffractograms of material of the invention and not of the invention.DETAILED DESCRIPTION

[0016] The cathode is comprised of an alloy of a lithium metal oxide and a borate salt. The metal oxide is Mn, Co, or Ni oxide that may be a mixture of single metal oxide individually alloyed or a complex oxide having 2 or more of these metals that are then alloyed with the borate salt. Desirably, the alloy is comprised of Mn and it may be advantageous for the metal oxide to be solely a manganese oxide. Generally, the amount of the lithium borate salt may be any useful 0.1%, 1%, 5% or 10% to at most about 30%, 25% or 20% by mole of the alloy.

[0017] Further salts may be alloyed with the metal oxides and borate salt. Illustratively, other salts such as sulfate and phosphate salts may be alloyed. Generally, the amount of theborate salt may be any useful 0.1%, 1%, 5% or 10% to at most about 30%, 25% or 20% by mole of the alloy. Typically, the amount of other salts alloyed are in an amount that is at most about 60%, 50%, or 40% to 5%, 10% or 20% by mole of the total amounts of salts alloyed with the metal oxide. Desirably, the further salt is comprised of or consists of a lithium phosphate (e.g., in the absence of the lithium sulfate). The total amount of the lithium salts (e.g., lithium sulfate, lithium borate and lithium phosphate) is the same as described above for the lithium borate salt. If lithium sulfate is used to form the alloy, it desirably is present in a minor amount of the lithium salts used and preferably is less than any other salt used to form the alloy such as when both lithium phosphate and lithium sulfate are present.

[0018] Alloy as previous described is realized by the formation of a diffuse singular phase with less distinct peaks corresponding to a rock salt structure in powder X-ray diffraction. The less distinctiveness may be due to the alloy having a more amorphous nature or due to the particle size of the alloy particles. Some residual amount of lithium metal oxide or lithium salt may be present, but generally is less than 1% by volume of the alloy, which may be determined using the internal method standard using X-ray diffraction. As an illustration, Figure 8 shows the X-ray diffractograms of the starting lithium cobalt oxide (8a), lithium sulfate (8b) and the final alloy (8c), distinctly showing the formation of a homogeneous alloy. It is understood that when describing the alloy as having, for example, lithium phosphate present, it is taken to mean that the alloy is made from the lithium metal oxide and lithium salt to form the alloy.

[0019] While the disclosure has been described in connection with certain embodiments, it is to be understood that the disclosure is not to be limited to the disclosed embodiments but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as is permitted under the law.

[0020] The alloys useful to make the cathodes, may be made by any suitable method. Illustratively, the alloy may be made by milling the lithium borate and lithium metal oxide under sufficient energy input and time to form the alloy, such as realized on lab-scale or commercial planetary mills and may include known vibratory milling, stirred media milling and the like.

[0021] The cathode may be used to form a lithium ion battery having a liquid electrolyte or desirably a solid state battery. Any suitable battery component may be employed to make the lithium ion batteries such as those known in the art including, but not limited to anodes, separators and electrolytes as well as containers, terminals and the like.ILLUSTRATIONS

[0022] Illustration 1. A cathode comprising an alloy of a lithium borate and a lithium metal oxide, wherein the metal is comprised of one or more of Co, Mn and Ni.

[0023] Illustration 2. The cathode of illustration 1, wherein the lithium borate is from 1% to 30% by mole of the alloy.

[0024] Illustration 3. The cathode of either illustration 1 or 2, wherein the alloy is further comprised of a lithium sulfate, lithium phosphate or combination thereof.

[0025] Illustration 4. The cathode of 3 wherein the alloy has at most 30% of the lithium phosphate, lithium sulfate and lithium borate.

[0026] Illustration 5. The cathode of illustration 4, wherein the lithium borate is at least 50% by mole of the lithium phosphate, lithium sulfate and lithium borate present in the alloy.

[0027] Illustration 6. The cathode of any one of the preceding illustrations, wherein lithium phosphate is present in the alloy.

[0028] Illustration 7. The cathode of illustration 6, wherein lithium sulfate is absent or present at an amount less than the amount of lithium phosphate present in the alloy.

[0029] Illustration 8. The cathode of any one of the preceding illustrations, wherein the metal is Mn.

[0030] Illustration 9. A battery comprised of the cathode of any of the preceding illustrations.

[0031] Illustration 10. The battery of illustration 9, wherein the battery is a solid state battery.EXAMPLES

[0032] Lithium metal oxides: LiNiCL, LiMnOz and LiCoCb are alloyed with lithium salts: L13PO4, Li2SO4 and LiBO at various concentrations of the total amount of these salts and at various ratios of these salts as shown in Figures 1 to 7. The alloys are made by milling under argon in a lab-scale planetary mill for 60 hours with periodic stops for sampling and disruption of any agglomerates that may have formed on the walls of the mill. Sixty hours is determined to be sufficient to essentially form the alloy as illustrated from alloys of LiCoOz and LhPCU.

[0033] The batteries are formed using standard techniques to make * / 2 coin cells (i.e. lithium metal sheet as anode). The cathode has 87% by weight of the alloy, 10% by weight of carbon nanotubes and 3% of polyvinyldifluoride, “PVDF” (SOLEF 5140 PVDF). Prior to mixing with the PVDF, the alloy is coated with 10% carbon through ball milling. The loading of the cathode is 3 mg / cm2. The electrolyte is a proprietary solid electrolyte. The separator is CELGARD 2400. The formation cycle is at 0.03C (-0.25 mA / cm2) and forcycling with no CV (constant voltage) step unless otherwise noted in Figures 1-7, for example, to exemplify the capacity at differing charge and discharge rates. From the results shown in Figures 1-7, it is clear that the lithium borate may realize increased initial capacity of cathodes made from these alloys. It is also clear that it may be desirable for the lithium borate to be in combination with another lithium salt such as lithium phosphate, particularly as shown in Fig. 5 at lithium salt concentrations of 10% to 20% alloyed with manganese oxide.

Claims

What is claimed is:

1. A cathode comprising an alloy of a lithium borate and a lithium metal oxide, wherein the metal of the lithium metal oxide is comprised of one or more of Co, Mn and Ni.

2. The cathode of claim 1, wherein the lithium borate is from 1% to 30% by mole of the alloy.

3. The cathode of claim 1, wherein the alloy is further comprised of a lithium sulfate, lithium phosphate or combination thereof.

4. The cathode of 3 wherein the alloy has at most 30% of the lithium phosphate, lithium sulfate and lithium borate.

5. The cathode of claim 4, wherein the lithium borate is at least 50% by mole of the lithium phosphate, lithium sulfate and lithium borate present in the alloy.

6. The cathode of claim 1, wherein lithium phosphate is present in the alloy.

7. The cathode of claim 6, wherein lithium sulfate is absent or present at an amount less than the amount of lithium phosphate present in the alloy.

8. The cathode of claim 1 , wherein the metal is Mn.

9. A battery comprised of the cathode of any of the preceding claims.

10. The battery of claim 9, wherein the battery is a solid state battery.

Images