Nickel- and cobalt-free cathodes for lithium-ion batteries and manufacturing methods

Abstract

A nickel-free and cobalt-free cathode for use in lithium (Li) batteries is provided. The cathode comprises Li a Al 1‑x‑y‑ z Fe x Mn y Zn z O 2‑d 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. 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 achieving high battery voltage and specific capacity comparable to or exceeding those of currently known Li(NiCoMn)O2 cathodes. The novel cathode chemistry according to embodiments of the present invention eliminates any potential cobalt supply problems and reduces the cost of the battery.

Description

Background Technology

[0001] In a typical solid-state lithium-ion battery (LIB), the anode and cathode are separated by an electrolyte. During the charging and discharging process, lithium ions move within the electrolyte between the anode and cathode.

[0002] Lithium cobalt oxide (LiCoO2) is commonly used as the cathode in lithium-ion batteries (LIBs). However, less than 10% of the cobalt supply comes as a primary product, with the remainder being a byproduct of nickel and copper production. Furthermore, the majority of global cobalt sources are concentrated in certain regions of the world, and there are growing concerns about child labor and unsafe working conditions in these areas.

[0003] Therefore, it is becoming increasingly difficult to meet the growing demand for Li-ion batteries, especially for electric vehicle (EV) applications where battery costs constitute a significant portion of the overall vehicle cost. Furthermore, current Li-ion battery technology cannot fully meet the requirements of current applications, and further development beyond current LIB technology is essential.

[0004] Recently, due to supply and cost issues related to cobalt availability, NCM (nickel, cobalt, manganese) and NCA (nickel, cobalt, aluminum) cathodes with reduced cobalt content are being used in EV applications. In addition, other cathode materials, including LiMn2O4 (lithium manganese oxide) with a spinel structure and olivine-type LiFePO4 (lithium iron phosphate), have been commercially available. Among these materials, LiCoO2 and NCM exhibit superior cycle life and charge / discharge efficiency and have been widely used. However, they are less competitive in applications requiring medium- to high-capacity batteries (such as EVs) because of their high cost due to the use of limited-supply nickel and cobalt. On the other hand, LiMn2O4 and LiFePO4 cathodes are less expensive and have abundant manganese / iron supplies, making them environmentally friendly, but their capacity is lower (140 mAh / g to 160 mAh / g).

[0005] Therefore, what is needed in the field is a nickel- and / or cobalt-free Li-ion battery, while simultaneously achieving high energy density to avoid supply issues and maintain cost competitiveness. However, it is difficult to completely eliminate cobalt from the cathode of a Li-ion battery (LIB) because doing so destabilizes the cathode's crystalline structure, leading to safety concerns.

[0006] However, given the technology considered as a whole when this invention was made, it is not obvious to those skilled in the art how to overcome the shortcomings of the prior art.

[0007] While certain aspects of conventional techniques have been discussed to facilitate the disclosure of this invention, the applicant does not deny these aspects and envisions that the claimed invention may cover one or more of the conventional techniques discussed herein.

[0008] This invention addresses one or more of the problems and deficiencies of the prior art discussed above. However, it is envisioned that this invention may prove useful in addressing other problems and deficiencies in many other technical fields. Therefore, the claimed invention should not be construed as limited to addressing any of the specific problems or deficiencies discussed herein.

[0009] In this specification, if a document, action, or knowledge item is referenced or discussed, such reference or discussion does not acknowledge that the document, action, or knowledge item, or any combination thereof, constitutes prior art as of the priority date, is publicly available, is known to the public, is part of common general knowledge, or otherwise is known to be related to any attempt to solve any problem covered in this specification. Summary of the Invention

[0010] In various embodiments, the present invention provides an improved Co-free / Ni-free Li-ion battery (LIB) cathode that exhibits good thermal stability and achieves high battery voltage and specific capacity comparable to or exceeding those of currently known Li(NiCoMn)O2 cathodes. The novel cathode chemistry according to embodiments of the present invention eliminates cobalt supply issues and reduces the cost of the battery.

[0011] Based on density functional theory (DFT) calculations, the inventors have determined the roles of Ni, Co, and Mn in NCM (nickel, cobalt, manganese) cathodes, where Mn stabilizes oxygen and Co / Ni compensates for Li+ removal. Through calculations on various elemental combinations, the inventors have determined that Al acts as Mn in NCM to stabilize oxygen, and Fe, Mn, and Zn act as Ni and Co. Calculations also show higher cell voltages for Al-Fe-Zn and Al-Mn-Zn combinations. Therefore, LiAl is proposed. x Fe y Zn z O2 and LiAl x Mn x Zn z O2 has been proposed as a novel cobalt-free cathode material.

[0012] Therefore, this invention provides a novel chemical composition for a cobalt-free layered transition metal oxide cathode for lithium-ion batteries. The proposed cobalt-free cathode offers lower costs and eliminates the future risk of unpredictable cobalt supply, enabling sustainable battery production.

[0013] The implementation method is applicable to a wide range of fields that require rechargeable batteries, including but not limited to electric vehicles, portable electronic devices, and various other applications that require high capacity, long cycle life, and low cost.

[0014] Therefore, the present invention includes features of construction, component combinations, and part arrangements exemplified in the disclosure set forth below, and the scope of the invention will be indicated in the claims. Attached Figure Description

[0015] For a more complete understanding of the present invention, reference should be made to the following detailed description in conjunction with the accompanying drawings, wherein:

[0016] Figure 1 This is a flowchart illustrating the coprecipitation method for synthesizing Li(AlFeMnZn)O2.

[0017] Figure 2 An exemplary XRD (x-ray diffraction) pattern of Li(AlMnFeZn)O2 (simulated) according to an embodiment of the present invention is shown. Detailed Implementation

[0018] In the following detailed description of preferred embodiments, reference is made to the accompanying drawings, which form part of the embodiments, and in the drawings, specific embodiments in which the invention may be practiced are illustrated by way of illustration. It should be understood that other embodiments and structural changes may be utilized without departing from the scope of the invention.

[0019] As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural indicators unless otherwise clearly stated. As used in this specification and the appended claims, the term “or” is generally used to mean “and / or” unless the context clearly indicates otherwise.

[0020] According to various embodiments, the present invention provides a novel Ni / Co-free cathode for use with Li-ion batteries, which is known to be subject to supply risks. Li-ion batteries employing the novel cathode achieve higher specific energy in the range of 160 mAh / g to 190 mAh / g compared to mainstream Li(NiCoMn)O2(NCM) cathodes.

[0021] The proposed cathode is a lithium-containing transition metal oxide with a layered rock salt structure (space group No. 166) containing at least one element from groups 1 to 3 listed below.

[0022] In response to the extraction / insertion of Li in the R3-m structure and the resulting changes in crystal structure and electronic state: 1) Group 1 elements provide structural stability, 2) Group 2 elements provide structural stability and compensation for charge changes, and 3) Group 3 elements provide only compensation for charge changes.

[0023] In NCM cathodes currently known in the art, Mn, Co, and Ni have been reported to function as Group 1, Group 2, and Group 3 elements, respectively. The functions described for Group 1 to Group 3 elements are determined based on the magnitude of the ionization tendency and energy of the transition metal or representative metal. If the atoms are arranged in order of ionization tendency (as shown below) and three atoms are selected, the one with the largest ionization tendency is designated as Group 1 element, followed by Group 2 and Group 3 elements with smaller ionization tendency values.

[0024] For example, in NCM, the ionization tendency of the three transition metals is Mn > Co > Ni, and they function as Group 1, Group 2, and Group 3 elements, respectively. The ionization energy order is Ni < Co < Mn.

[0025] 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

[0026] 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

[0027] The cathode proposed in this invention does not contain Ni or Co, and the elements are selected from the following list, which are advantageous as elements in groups 1 to 3.

[0028] B, C, Na, Mg, Al, Si, P, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Cu, Zn

[0029] 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:

[0030]

[0031] Al has a fixed charge of 3+ and becomes a group 1 element when it combines with Fe, Zn or Mn. The ionization energies of the three other elements are in the order Mn < Fe < Zn, thus grouping is performed.

[0032] Due to their layered rock salt structure, these materials should exhibit XRD peaks between 2θ = 17.5–20.5° (Cu-Kα X-ray source, where λ = 0.15418 nm).

[0033] Common synthetic methods for Li complex oxides include coprecipitation, citrate processes, hydrothermal processes, ion exchange, and solid-state reactions. The proposed cathode can be synthesized using these processes and is not limited by the chosen synthetic method. An example of a coprecipitation method used to synthesize the proposed cathode is explained below.

[0034] Generally, a precursor composed of multiple transition metals is prepared by co-precipitation, which is then mixed with a Li complex and the mixture is calcined. Figure 1 The flowchart illustrating the coprecipitation process is shown in the figure.

[0035] like Figure 1 As shown, nitrates, sulfates, hydrochlorides, and carboxylates can be used to synthesize precursors. Using, for example... Figure 1 The synthetic route shown can synthesize cathode active materials with the following composition:

[0036] Li a Al 1-x-y-z Fe x Mn y Zn z O 2-d Where a, x, y, z, and δ are within the following ranges:

[0037] 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.

[0038] The cathode synthesized by the method outlined above comprises a Li-containing transition metal oxide having space group R3-m (No. 166). This invention provides a cathode material for Li-ion secondary batteries containing at least 0.01 mol% Al as a representative elemental metal and at least two transition metals selected from Mn, Fe, and Zn.

[0039] The powder XRD pattern of the cathode is as follows: Figure 2 As shown (Bruker D3 Advance, l = 0.15418 nm, Cu-Kα X-ray source). Figure 2 As shown, the synthetic cathode according to the present invention should contain at least one peak corresponding to a lattice spacing of (104), (110), (113), (101), (102), or (003). The observed 003 peak should be located between 2θ = 17.5° and 20.5°.

[0040] References

[0041] [1]Muralidharan, Nitin, Essehli, Rachid, Hermann, Raphael P., Parejiya, Anand Vasudevbhai, Amin, Ruhul, Bai, Yaocai, Du, Zhijia, and Belharouak, Elias, LiNi x Fe y Al z O2,a novel cobalt-free layered cathode material for advanced Li-ion batteries,J.Power Sources,471(2020),228389.

[0042] [2]Li,W.,Lee,S.,Manthiram,A.,High-Nickel NMA:A Cobalt-FreeAlternative to NMC and NCA Cathodes for Lithium-Ion Batteries.Adv.Mater.2020,32,2002718.

[0043] [3]Cui Z,Xie Q,Manthiram A.,Zinc-Doped High-Nickel,Low-Cobalt Layered Oxide Cathodes for High-Energy-Density Lithium-Ion Batteries.ACS AppliedMaterials&Interfaces.2021Apr.13(13):15324-15332.

[0044] [4]Masaaki Hirayama,Hiroki Tomita,Kei Kubota,Ryoji Kanno,Structureand electrode reactions of layered rocksalt LiFeO2 nanoparticles for lithium battery cathode,J.Power Soures,196(2011),6809:Introduces LiFeO2 layeredcathode for lithium ion battery electrode material.

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

[0046] The advantages described above, as well as those obvious from the foregoing description, are obtained efficiently. Since certain changes can be made to the above construction without departing from the scope of the invention, everything contained in the foregoing description or shown in the accompanying drawings should be interpreted as illustrative rather than restrictive.

[0047] It will also be understood that the following claims are intended to cover all general and specific features of the invention described herein and all statements regarding the scope of the invention, and in terms of language, may be said to fall somewhere in between.

Claims

1. A cathode for use in a lithium (Li)-ion battery, the cathode comprising: Li a Al 1-x-y-z Fe x Mn y Zn z O 2-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, and the cathode comprises Zn, and any one of Fe and Mn, and comprises a Li-containing transition metal oxide having space group R3-m, wherein space group R3-m is No.

166. The cathode does not contain Ni or Co.

2. The cathode of claim 1, wherein the Li-containing transition metal oxide is synthesized using a synthesis method selected from co-precipitation, citrate process, hydrothermal, ion exchange and solid-state reaction.

3. A lithium-ion battery, comprising: Cathode, the cathode comprising Li a Al 1-x-y-z Fe x Mn y Zn z O 2-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, and the cathode contains Zn, and any one of Fe and Mn, and contains a Li-containing transition metal oxide having space group R3-m, and the cathode does not contain Ni and Co, wherein the space group R3-m is No.

166. Anode; and An electrolyte, wherein the electrolyte is positioned between the anode and the cathode.

4. A method for synthesizing a cathode for use in a Li-ion battery, the method comprising: One or more precursors are prepared at a desired ratio, the one or more precursors comprising Zn, and any one of Fe and Mn, and containing a Li-containing transition metal oxide having space group R3-m, wherein space group R3-m is No. 166; Prepare one or more Li complexes; Mix the one or more precursors with the one or more Li complexes; A mixture of the one or more precursors and the one or more Li complexes is calcined to synthesize a cathode, the cathode comprising Li. a Al 1-x-y-z Fe x Mn y Zn z O 2-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, and the cathode contains Zn, and any one of Fe and Mn, and contains a Li-containing transition metal oxide having space group R3-m, and the cathode does not contain Ni and Co.

5. The method of claim 4, wherein one or more nitrates, sulfates, hydrochlorides and carboxylates are used to prepare the one or more precursors.

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