NICKEL AND COBALT-FREE CATHODE FOR LITHIUM-ION BATTERIES AND METHOD OF MANUFACTURE

Abstract

A nickel-free and cobalt-free cathode material for a lithium (Li) battery is provided. The cathode material includes, Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2-δ, wherein a, x, y, z, and δ are in the following ranges: 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1. In various embodiments, the present invention provides an improved Co-free/Ni-free Li-ion battery (LIB) cathode that exhibits good thermal stability and is capable of realizing a high cell voltage and specific capacity comparable to, or exceeding, currently known Li(NiCoMn)O.sub.2 cathodes. The novel cathode chemistry in accordance with the embodiments of the present invention eliminates any potential cobalt supply issues and lowers the overall cost of the battery.

Claims

1. A cathode material for use in a lithium (Li)-ion battery, the cathode material comprising: Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2-δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1.

2. The cathode material of claim 1, wherein the cathode material does not comprise cobalt (Co).

3. The cathode material of claim 1, wherein the cathode material does not comprise nickel (Ni).

4. The cathode material of claim 1, wherein the cathode material comprises at least 0.01 mol% Al and at least two transition metals selected from Mn, Fe and Zn.

5. The cathode material of claim 1, wherein the cathode material is synthesized using a method selected from co-precipitation, citrate process, hydrothermal, ion exchange and solid-state reactions.

6. A lithium (Li)-ion battery (LIB) comprising: a cathode composed of a cathode material comprising Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2- .sub.δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1. an anode; and an electrolyte positioned between the anode and the cathode.

7. The LIB of claim 6, wherein the cathode material does not comprise cobalt (Co).

8. The LIB of claim 6, wherein the cathode material does not comprise nickel (Ni).

9. The LIB of claim 6, wherein the cathode material comprises at least 0.01 mol% Al and at least two transition metals selected from Mn, Fe and Zn.

10. The LIB of claim 6, wherein the cathode material is synthesized using a method selected from co-precipitation, citrate process, hydrothermal, ion exchange and solid-state reactions.

11. A method for synthesizing a cathode material for a cathode of a lithium (Li)-ion battery, the method comprising: synthesizing one or more precursors comprising two or more transition metals selected from Al, Mn, Fe and Zn in a predetermined ratio; preparing one or more Li composites; mixing the one or more precursors with the one or more Li composites; and calcinating the mixture of the one or more precursors with the one or more Li composites to synthesize a cathode material comprising Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2- .sub.δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1.

12. The method of claim 11, wherein the one or more precursors do not comprise cobalt (Co).

13. The method of claim 11, wherein the one or more precursors do not comprise nickel (Ni).

14. The method of claim 11, wherein the one or more precursors comprise at least 0.01 mol% Al and at least two transition metals selected from Mn, Fe and Zn.

15. The method of claim 11, wherein the one or more Li composites is selected from LiCH.sub.3COO, LiCl, LiOH, LiNO.sub.3, Li.sub.2CO.sub.3, LiBr, LiCl, Li.sub.3C.sub.6H.sub.5O.sub.7, LiF, Lil, CH.sub.3CH(OH)COOLi, Li.sub.3PO.sub.4, CH.sub.3COCOOLi, Li.sub.2OS.sub.4 and Li.sub.2O.

16. The method of claim 11, wherein synthesizing the one or more precursors comprising two or more transition metals further comprises: dissolving the two or more transition metal composites in solution; mixing the solution of the two or more transition metal composites with one or more complexing agents selected from nitrates, sulfates, hydrochlorides, and carboxylates; and performing co-precipitation to synthesize the one or more precursors comprising the two or more transition metals.

17. The method of claim 11, further comprising, washing, filtrating and drying the one or more precursors prior to mixing the one or more precursors with the one or more Li composites.

18. The method of claim 11, further comprising, pulverizing, washing and drying after calcinating the mixture of the one or more precursors with the one or more Li composites to synthesize the cathode material comprising Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2- .sub.δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a fuller understanding of the invention, reference should be made to the following detailed description, taken in connection with the accompanying drawings, in which:

[0021] FIG. 1 is a flow diagram illustrating an exemplary co-precipitation method to synthesize Li(AlFeMnZn)O.sub.2, in accordance with an embodiment of the present invention.

[0022] FIG. 2 illustrates exemplary XRD (x-ray diffraction) patterns of Li(AlMnFeZn)O.sub.2 (simulated), in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0023] In the following detailed description of the preferred embodiments, reference is made to the accompanying drawings, which form a part thereof, and within which are shown by way of illustration specific embodiments by which the invention may be practiced. It is to be understood that other embodiments may be utilized, and structural changes may be made without departing from the scope of the invention.

[0024] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. As used in this specification and the appended claims, the term “or” is generally employed in its sense including “and/or” unless the context clearly dictates otherwise.

[0025] In accordance with various embodiments, the present invention provides a novel cathode for use with Li-ion batteries, that does not contain Ni or Co. A Li-ion battery employing the novel cathode achieves higher specific energy, when compared to a mainstream Li(NiCoMn)O.sub.2 (NCM) cathode, with 160-190 mAh/g.

[0026] The proposed cathode is a lithium containing transition metal oxide with layered rock-salt structure (space group No. 166) that contains at least one element from Group 1-3, as described in more detail below.

[0027] In response to extraction/insertion of Li in R3-m structure and the resulting changes in the crystal structure and electronic state: 1) Group 1 elements provide structural stabilities, 2) Group 2 elements provide both structural stability and compensation for the changes in the electric charges, and 3) Group 3 elements only provide compensation for the changes in the electric charges.

[0028] In the NCM cathodes currently known in the art, it is reported that Mn, Co, and Ni function as Group 1, 2, and 3 elements, respectively. The functions described for Groups 1-3 elements are determined based on the magnitude of the ionization tendencies and energies of the transition metal or representative metals. If one arranges atoms in the order of the ionization tendencies (as shown below) and then selects three atoms, the one with the largest ionization tendencies functions as a Group 1 element, followed by Group 2 and 3 elements for the ones with the smaller ionization tendency values.

[0029] For example, in NCM, the order of ionization tendencies of the three transition metals is Mn > Co > Ni functioning as Group 1, 2, and 3 elements, respectively. The order of the ionization energy is Ni < Co < Mn.

[0030] Ionization tendency: Li > Cs > Rb > K > Ba > Sr > Ca > Na > Mg > Th > Be > Al > Ti > Zr > Mn > Ta > Zn > Cr > Fe > Cd >Co > Ni > Sn > Pb > H2 > Sb > Bi > Cu > Hg > Ag > Pd > Ir > Pt > Au

[0031] Ionization energy: Ba < Ce < Sr < Ca < Sc < Zr < Ti < Nb < Sn < Pb < Mg < Mn < Ge < Mo < Fe < Si < Cr < Sb < Bi < Co < W < Zn < Ni < Cu

[0032] The proposed cathode material of the present invention does not contain Ni or Co, the elements are selected from the following list that are favorable as Group 1-3 elements: B, C, Na, Mg, Al, Si, P, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Cu, Zn

[0033] In particular, Al, Mn, Zn, and Fe are ideal elements because of their high theoretical capacity/potential and availability. The combinations of these elements and their functions are as follows:

TABLE-US-00001 Li(AlMnFe)O.sub.2 Al works as Mn in NCM (structural stability) Mn works as Co in NCM (charge compensation + stability) Fe works as Ni in NCM (charge compensation) Group 1 Group 2 Group 3 Li(AlZnFe)O.sub.2 Al works as Mn in NCM (structural stability) Fe works as Co in NCM (charge compensation + stability) Zn works as Ni in NCM (charge compensation) Group 1 Group 2 Group 3 Li(AlMnZn)O.sub.2 Al works as Mn in NCM (structural stability) Mn works as Co in NCM (charge compensation + stability) Zn works as Ni in NCM (charge compensation) Group 1 Group 2 Group 3

[0034] Al charge is fixed at 3+ and becomes Group 1 element when combined with Fe, Zn, or Mn, and the order of the ionization energies of the three other elements is Mn < Fe < Zn, hence the group allocations.

[0035] These materials, since they have layered rock-salt structure, should show XRD peaks between 2θ = 17.5 - 20.5° (Cu-Kα X-ray source with λ = 0.15418 nm).

[0036] Commonly used synthesis methods for Li composite oxides include, co-precipitation, citrate process, hydrothermal, ion exchange, and solid-state reactions. The proposed cathode can be synthesized using these processes and is not limited by the synthesis method selected. An example using the co-precipitation method for synthesizing the proposed cathode is explained below with reference to FIG. 1

[0037] Co-precipitation, in general, prepares precursors consisting of multiple transition metals, mixes them with Li composites, and calcinates the mixture. A flow chart illustrating the co-precipitation process is shown in FIG. 1.

[0038] With reference to FIG. 1, in general, the method for synthesizing a cathode material for a cathode of a lithium (Li)-ion battery includes synthesizing one or more precursors comprising two or more transition metals selected from Al, Mn, Fe and Zn in a predetermined ratio 125, preparing one or more Li composites 145, mixing the one or more precursors with the one or more Li composites 140 and calcinating the mixture of the one or more precursors with the one or more Li composites 150 to synthesize a cathode material comprising Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2. .sub.δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1.

[0039] As shown in FIG. 1, the one or more Li composites may be selected from LiCH.sub.3COO, LiCl, LiOH, LiNO.sub.3, Li.sub.2CO.sub.3, LiBr, LiCl, Li.sub.3C.sub.6H.sub.5O.sub.7, LiF, Lil, CH.sub.3CH(OH)COOLi, Li.sub.3PO.sub.4, CH.sub.3COCOOLi, Li.sub.2OS.sub.4 and Li.sub.2O. Additionally, nitrates, sulfates, hydrochlorides, and carboxylates can be used to synthesize the precursors.

[0040] More specifically, synthesizing the one or more precursors includes, dissolving the two or more transition metal composites in solution 105, mixing the solution of the two or more transition metal composites with one or more complexing agents selected from nitrates, sulfates, hydrochlorides, and carboxylates 115 and performing co-precipitation 120 to synthesize the one or more precursors comprising the two or more transition metals.

[0041] The method further includes washing/filtrating 130 and drying 135 the one or more precursors prior to mixing the one or more precursors with the one or more Li composites 140. The method also includes, pulverizing 155, washing 160 and drying 165 following the calcinating 150 the mixture of the one or more precursors with the one or more Li composites to synthesize the cathode material comprising Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2- .sub.δ, wherein a, x, y, z, and δ are in a range of 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1.

[0042] Using the synthesis route as illustrated in FIG. 1, cathode active materials with the following compositions can be synthesized: Li.sub.aAl.sub.1-x-y-z Fe.sub.xMn.sub.yZn.sub.zO.sub.2- .sub.δ, where a, x, y, z, and δ are in the following ranges: 0.95 ≤ a ≤ 1.2; 0 ≤ x ≤ 0.3; 0 ≤ y ≤ 0.3; 0 ≤ z ≤ 0.3; 0.5 ≤ x + y + z ≤ 0.99; 0 ≤ δ ≤ 0.1

[0043] The cathode synthesized by the method as outlined above comprises a Li containing transition metal oxide with space group R3-m (No.166). The invention provides a cathode material for Li-ion secondary batteries that contains at least 0.01 mol% of Al as a representative elemental metal and no less than two transition metals selected from Mn, Fe, and Zn.

[0044] Powder XRD patterns of the cathode described above are shown in FIG. 2 (Bruker D3 Advance, 1 = 0.15418 nm, Cu-Kα X-ray source). As illustrated in FIG. 2, the synthesized cathode in accordance with the present invention should contain at least one peak corresponding to (104), (110), (113), (101), (102), or (003) lattice spacings. The observed 003 peak should be located between 20 = 17.5° to 20.5°.

[0045] All referenced publications are incorporated herein by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply.

[0046] The advantages set forth above, and those made apparent from the foregoing description, are efficiently attained. Since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

[0047] It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.