Cathode composition

Abstract

A cathode composition for a battery of the following general formula is provided: Mg1+xNi1-xO2 or Mg1+xMn1-xO2; wherein the value of x is greater than 0. Additionally, a method for manufacturing a cathode composition for a battery, a cathode comprising said cathode composition, and an electrochemical cell comprising said cathode are provided.

Description

Technology Field

[0001] The present invention relates to a cathode composition. More specifically, the present invention relates to a cathode composition for a battery. The present invention further relates to a method for manufacturing a cathode composition for a battery. The present invention further relates to a cathode comprising a cathode composition and an electrochemical cell comprising said cathode. Background Technology

[0002] Lithium-rich cathode compositions for batteries are widely known. Typically, lithium-rich cathodes require a layered structure, which can lead to problems such as defects, trapped lithium ions, and the breakdown of layers during battery cycling. Furthermore, lithium-rich cathode compositions are generally manufactured through high-temperature synthesis, which is energy-intensive, costly, and can cause difficulties in controlling the reactions that occur to form the composition. More recently, lithium-rich disordered rock salt (DRS) structures have been studied as cathode materials. However, improving the energy density of lithium-rich DRS structures using known compositions and methods is a current challenge to overcome.

[0003] The present invention is designed to alleviate or overcome at least some of the aforementioned problems.

[0004] Summary of the Invention

[0005] According to a first aspect of the present invention, a cathode composition for a battery of the following general formula is provided: Mg 1+x Ni 1-x O2 or Mg 1+x Mn 1-x O2; In the above equation, the value of x is greater than 0.

[0006] The present invention provides a magnesium-based cathode composition for a battery that is stable and electrochemically active. In this composition, magnesium is the primary charge carrier rather than lithium, as in conventional lithium-ion batteries. Magnesium-based cathode compositions are difficult to manufacture synthetically; however, the inventors have shown for the first time that not only can the magnesium-based cathode composition be manufactured, but it can also be manufactured and cycled in a simple manner.

[0007] The composition itself is less expensive to produce and more practical than any previously reported cathode composition. In addition, the inventors have demonstrated electrochemical activity in this composition for the first time. Advantageously, the magnesium ion insertion process involves the insertion of two electrons, which can significantly improve the energy density and stability of the cathode compared to lithium-based cathode compositions.

[0008] The composition may be in the form of a single phase having a rock salt crystal structure such that the x-ray diffraction pattern of the composition using a Cu Ka radiation source does not have a peak at a value of less than 2θ of 35.

[0009] Conventional aligned or layered lithium and manganese-rich compositions (L h+x Tm i-x C k Here, Tm (where Tm is mainly Mn) has lithium ions in both alkaline and transition metal sites. In addition to the above, the X-ray diffraction pattern of such conventional compositions will have a peak at the 2θ value of 18. However, in the present invention, the X-ray diffraction pattern of the cathode composition does not have a peak at the 2θ value of 18. In other words, the single-phase crystal structure of the present invention has no spinel or layered structure and is considered to be a purely single-phase rock salt crystal structure. The single-phase crystal structure does not exhibit the R3(bar)m and / or C2 / m space group.

[0010] In particular, the above composition is provided as a single-phase rock salt crystal structure (i.e., a face-centered cubic lattice having an Fm3(bar)m space group), which may be a disordered rock salt crystal structure.

[0011] The value of x may be approximately 0.3 or less.

[0012] The composition is Mg 1.2 Ni 0.8 It could be O2.

[0013] The composition is Mg 1.2 Mn 0.8 It could be O2.

[0014] The value of x may be approximately 0.15 or less.

[0015] According to a second aspect of the present invention, a method for preparing a cathode composition according to a first aspect is provided, the method comprising the following steps: providing a magnesium nickel oxide precursor or a magnesium manganese oxide precursor; forming a cathode composition by high-energy milling the precursor using a plurality of milling balls at a constant milling speed for a constant milling period; wherein the magnesium nickel oxide precursor or the magnesium manganese oxide precursor has an oxidation state identical to the oxidation state of each component in the cathode composition.

[0016] Unlike known high-temperature synthesis methods, the present method for preparing a cathode composition does not require high temperatures. Furthermore, the present method provides greater control over the oxidation state of the transition metal in the composition because the precursor can be selected according to the required oxidation state, and applying the method to the precursor produces a cathode composition based on the oxidation state of the precursor without any risk of oxidation during the milling process.

[0017] The milling speed can be at least approximately 400 rpm.

[0018] The milling speed can be approximately 400 rpm to approximately 1000 rpm.

[0019] The milling speed can be approximately 400 rpm to approximately 800 rpm.

[0020] The milling speed can be approximately 800 rpm.

[0021] The milling period can be approximately 10 hours to approximately 180 hours.

[0022] The milling period can be approximately 40 hours to approximately 100 hours.

[0023] The milling period can be approximately 40 hours to approximately 80 hours.

[0024] The milling period may be approximately 40 hours to approximately 60 hours.

[0025] The ratio of precursor powder to milling balls by weight can be 1:4 to 1:20.

[0026] The magnesium nickel oxide precursor may contain magnesium oxide and nickel oxide in a molar ratio of 1+x magnesium oxide to 1-x nickel oxide.

[0027] The magnesium manganese oxide precursor may contain magnesium oxide and manganese oxide in a molar ratio of 1+x magnesium oxide to 1-x manganese oxide.

[0028] Multiple milling balls may contain tungsten carbide.

[0029] High-energy milling can be performed in a ball mill jar containing tungsten carbide.

[0030] Multiple milling balls may contain zirconium oxide.

[0031] High-energy milling can be performed in a ball mill vessel containing zirconium oxide.

[0032] Each of the multiple milling balls can have a diameter of approximately 0.5 mm to approximately 1 cm.

[0033] According to a third aspect of the present invention, a cathode comprising a cathode composition according to a first aspect is provided.

[0034] According to a fourth aspect of the present invention, an electrochemical cell comprising a cathode, an electrolyte, and an anode according to a third aspect is provided.

[0035] Within the scope of this application, it is expressly intended that the various embodiments, embodiments, examples, and alternatives, and in particular the individual features thereof, presented in the paragraphs, claims, and / or description and drawings below may be taken independently or in any combination. That is, all embodiments and / or features of any embodiments may be combined in any manner and / or combination, as long as such features are compatible. The applicant has the right to modify any originally submitted claim or to submit a new claim accordingly, including the right to modify any originally submitted claim to follow and / or incorporate any features of any other claim that were not originally claimed in such a manner. Brief explanation of the drawing

[0036] One or more embodiments of the invention will be described below merely as examples with reference to the attached drawings: Figure 1 shows the cathode composition Mg in Example 1. 1.2 Ni 0.8 Representing the potential as a function of capacitance with respect to O2; Figure 2 shows the cathode composition Mg in Example 2. 1.2 Mn 0.8 Representing the potential as a function of capacitance with respect to O2; Figure 3 shows the cathode composition Mg in Example 2. 1.2 Mn 0.8 This shows the X-ray diffraction pattern of O2. Specific details for implementing the invention

[0037] The present invention relates to a cathode composition for a battery of the following general formula: Mg 1+xNi 1-x O2 or Mg 1+x Mn 1-x O2; In the above equation, the value of x is greater than 0.

[0038] The above composition has a disordered rock salt structure, that is, it includes regions of rock salt having different cations, wherein said regions are disordered. In this way, the rock salt effectively forms a complex rock salt material.

[0039] The inventors determined that the cathode composition could be manufactured using ball milling technology. The starting material is selected according to the desired cathode material, which will be described in more detail below. The starting material is then subjected to ball milling for a certain milling period. The ball milling process is typically carried out at low temperatures or room temperature to ensure that the oxidation state of the metal cation is not altered during the process. Milling parameters can be appropriately selected. After the ball milling process is completed, the resulting material is a disordered rock salt cathode composition.

[0040] The ball milling process advantageously enables the oxidation state of the metal to be maintained in the final cathode composition. In this way, the oxidation state and the resulting final cathode composition can be carefully controlled.

[0041] Mg 1+x Ni 1-x For the O2 composition, the starting material is magnesium nickel oxide. The magnesium nickel oxide comprises a mixture of MgO and NiO, which is preferably provided in powder form. The ratio of MgO to NiO is selected according to the value of x in the final composition. In particular, the molar ratio of MgO to NiO is 1+x to 1-x.

[0042] Mg 1+x Mn 1-xFor the O2 composition, the starting material is magnesium manganese oxide. The magnesium manganese oxide comprises a mixture of MgO and MnO, which is preferably provided in powder form. The ratio of MgO to MnO is selected according to the value of x in the final composition. In particular, the molar ratio of MgO to MnO is 1+x to 1-x.

[0043] The ball milling process parameters can be any suitable parameters. In particular, they are as follows:

[0044] The ball milling period is sufficient time to prepare the cathode composition, which can be, for example, at least 10 hours.

[0045] The material of the ball and / or container may be any suitable material, such as, for example, tungsten carbide or zirconium oxide.

[0046] The ratio of balls to precursors can be any suitable ratio that provides sufficient milling to produce the cathode composition. For example, the ratio of precursors to milling balls by weight can be 1:4 to 1:20, while other suitable ratios may be used.

[0047] The milling speed can be any suitable milling speed sufficient for manufacturing the cathode composition, which can be, for example, at least approximately 400 rpm.

[0048] The composition can be incorporated into the cathode in any suitable form.

[0049] An aspect of the present invention includes a method for manufacturing a cathode composition for a battery, a cathode comprising said cathode composition, and an electrochemical cell comprising said cathode.

[0050] The present invention will be illustrated below with reference to the following embodiments.

[0051] Example 1

[0052] Mg 1.2 Ni 0.8 O2

[0053] A magnesium nickel oxide (MgNiO2) precursor was prepared to have a molar ratio of 1.2 MgO to 0.8 NiO. This corresponded to 8.95 g (44.75 wt%) MgO and 11.05 g (55.25 wt%) NiO. The precursor was provided in a 20 ml ball milling vessel made of tungsten carbide. Eighty tungsten carbide milling balls, each with a diameter of 5 mm, were also provided in the ball milling vessel. The precursor was milled using high-energy milling at a milling speed of 800 rpm for a milling period of at least 10 hours to form a cathode composition of the following chemical formula: Mg 1.2 Ni 0.8 O2. With this, 20 g of Mg in a ball mill container 1.2 Ni 0.8 It forms O2 powder. The composition has a disordered rock salt crystal structure. The oxidation state of Mg in MgO and the oxidation state of Ni in NiO is +2. Cathode composition Mg 1.2 Ni 0.8 The oxidation state of Mg and Ni in O2 is also +2. Figure 1 shows the cathode composition Mg 1.2 Ni 0.8 It represents the potential as a function of capacity with respect to O2, which demonstrates that the composition can be efficiently cycled.

[0054] Example 2

[0055] Mg 1.2 Mn 0.8 O2

[0056] Magnesium manganese oxide (MgMnO2) The precursor was prepared to have a molar ratio of 1.2 MgO to 0.8 MnO. This corresponded to 9.20 g (46 wt%) MgO and 10.80 g (54 wt%) MnO. The precursor was provided in a 20 ml ball milling vessel made of tungsten carbide. Eighty tungsten carbide milling balls, each with a diameter of 5 mm, were also provided in the ball milling vessel. The precursor was milled using high-energy milling at a milling speed of 800 rpm for a milling period of at least 10 hours to form a cathode composition of the following chemical formula: Mg 1.2 Mn 0.8 O2. With this, 20 g of Mg in a ball mill container 1.2 Mn 0.8 It forms O2 powder. The composition has a disordered rock salt crystal structure. The oxidation state of Mg in MgO and the oxidation state of Mn in MnO is +2. Cathode composition Mg 1.2 Mn 0.8 The oxidation state of Mg and Mn in O2 is also +2. Figure 2 shows the cathode composition Mg 1.2 Mn 0.8 It represents the potential as a function of capacity with respect to O2, which demonstrates that the composition can be efficiently cycled.

[0057] Cathode composition Mg 1.2 Mn 0.8 The X-ray diffraction pattern of O2 is shown in Fig. 3, which confirms the crystalline structure of the composition. The XRD pattern is characterized by a cationic disordered rock salt structure. The pattern is shown to exhibit a broad main peak consistent with a face-centered cubic lattice having the Fm3(bar)m space group, as shown in Fig. 3.

[0058] Various modifications may be made to the specific embodiments described above without departing from the scope of the invention as defined in the appended claims. Features of one embodiment may be used in other embodiments as an addition to or as a substitute for such embodiment.

Claims

Claim 1 Cathode composition for a battery of the following general formula: Mg 1+x Ni 1-x A cathode composition having a single phase form having a rock salt crystal structure such that, in the above formula, the value of x is greater than 0 and less than 1, and the X-ray diffraction pattern of the composition using a Cu Ka radiation source does not have a peak at a value less than 2θ=35°. Claim 2 A cathode composition according to claim 1, wherein the value of x is 0.3 or less. Claim 3 In paragraph 1, Mg 1.2 Ni 0.8 O2 cathode composition. Claim 4 A cathode composition according to claim 1, wherein the value of x is 0.15 or less. Claim 5 A method for manufacturing a cathode composition according to any one of claims 1 to 4, comprising the step of providing a magnesium nickel oxide precursor; and the step of forming a cathode composition by high-energy milling the precursor using a plurality of milling balls at a constant milling speed for a constant milling period, wherein the magnesium nickel oxide precursor has an oxidation state identical to the oxidation state of each component in the cathode composition. Claim 6 A manufacturing method according to claim 5, wherein the milling speed is at least 400 rpm. Claim 7 A manufacturing method according to claim 6, wherein the milling speed is 400 rpm to 1000 rpm. Claim 8 A manufacturing method according to claim 7, wherein the milling speed is 400 rpm to 800 rpm. Claim 9 A manufacturing method according to claim 8, wherein the milling speed is 800 rpm. Claim 10 A manufacturing method according to claim 5, wherein the milling period is 10 to 180 hours. Claim 11 A manufacturing method according to claim 10, wherein the milling period is 40 to 100 hours. Claim 12 A manufacturing method according to claim 11, wherein the milling period is 40 to 80 hours. Claim 13 A manufacturing method according to claim 12, wherein the milling period is 40 to 60 hours. Claim 14 A manufacturing method according to claim 5, wherein the ratio of precursor powder to milling balls by weight is 1:4 to 1:

20. Claim 15 In claim 5, the magnesium nickel oxide precursor is a method of preparation comprising magnesium oxide and nickel oxide in a molar ratio of 1+x magnesium oxide to 1-x nickel oxide. Claim 16 In paragraph 5, a manufacturing method comprising a plurality of milling balls including tungsten carbide. Claim 17 In paragraph 16, the manufacturing method wherein high-energy milling is performed in a ball mill vessel containing tungsten carbide. Claim 18 In paragraph 5, a manufacturing method comprising a plurality of milling balls containing zirconium oxide. Claim 19 In paragraph 18, the manufacturing method wherein high-energy milling is performed in a ball mill vessel containing zirconium oxide. Claim 20 In claim 5, a manufacturing method wherein each of the plurality of milling balls has a diameter of 0.5 mm to 1 cm. Claim 21 A cathode comprising a cathode composition according to any one of claims 1 to 4. Claim 22 An electrochemical cell comprising a cathode, an electrolyte, and an anode according to paragraph 21. Claim 23 delete Claim 24 delete Claim 25 delete

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