Irregular Rock Salt-Type Material and Method for Forming the Same

Abstract

The disordered rock salt type (DRS) having improved properties has a cation containing lithium and one other metal, and an anion containing oxygen and fluorine, and one or more of phosphorus, sulfur, and nitrogen. Substituting one or more of P, S, and N at the oxygen anion site can achieve an improved cycle life of the battery and / or can be useful for fabricating a safer battery.

Description

【Technical Field】 【0001】 The present invention relates to the field of battery technology. 【Background Art】 【0002】 Lithium metal oxides are used to formulate cathode materials for lithium-ion batteries. The cathode is derived from several basic crystallographic structural types, such as spinel-type, olivine-type, and layered oxide structures. The layered oxide structure includes a lithium-excess type structure, and additional lithium is present within the structure. 【0003】 Recently, irregular rock-salt-type structures, such as those formed from certain lithium metal oxides, have attracted attention. Compounds represented by the following formula: xLi 3 NbO 4 ·(1-x)LiMO 2 (1) (wherein M is a divalent or trivalent cation) have been shown to be a promising class of transition metal oxides for use as cathodes in lithium-ion batteries. The compounds of formula (1) are considered to have an irregular rock-salt type in which the random atomic arrangement of lithium and transition metal ions is filled in the closest cubic structure. These irregular rock-salt type compositions provide the ability to contain up to three lithium atoms per formula unit, which is more than conventional lithium-excess type layered materials. Formula (1) can be expressed as converted to Li x M y N z O w and represented. 【0004】 The irregular rock-salt type structure is an attractive cathode material for next-generation lithium-ion batteries because it has a higher specific energy density (e.g., a higher theoretical energy density) than state-of-the-art cathode materials such as layered lithium metal oxide structures. For example, certain irregular rock-salt type structure materials have a theoretical weight energy density of about 1120 Wh / kg, while LiMn 2 O 4The active material has a theoretical weight energy density of about 492 Wh / kg, and LiMn 1.5 Ni 0.5 O 4 has a theoretical weight energy density of about 691 Wh / kg. This energy density is particularly attractive when relatively low-cost raw materials such as manganese are used as components of the disordered rock salt structure. Thus, disordered rock salt-type materials can achieve a relatively high energy density at a relatively low material cost. To achieve an equivalent energy density, known cathode materials require relatively high-cost raw materials such as cobalt or nickel. 【0005】 Disordered rock salt-type materials tend to have a shorter cycle life compared to current lithium-ion batteries. Recently, as described in Patent Document 1, attempts have been reported to improve the cycle life of disordered rock salt-type batteries by substituting a part of oxygen with fluorine. However, there is still a desire to provide a battery including a disordered rock salt-type cathode that has a longer life and other desirable attributes such as a safer battery. 【Prior Art Documents】 【Patent Documents】 【0006】 【Patent Document 1】 U.S. Patent No. 10,280,092 【Summary of the Invention】 【0007】 The inventors have discovered an improved disordered rock salt type (DRS). The DRS can exhibit a longer long - term cycle life. The DRS can show a lower oxygen redox voltage, which can further enable a safer battery (showing a lower charge voltage plateau on the oxygen redox plateau). The low charge voltage of the plateau is an advantage in that the battery's electrolyte is exposed to conditions less likely to cause oxidation. Adding F in combination with any one or all of P, S, and N has been found to result in the aforementioned desirable attributes while maintaining the same initial capacity, and at the same time, the life and other attributes are also improved. Each of these replaces a part of the oxygen (anion) in the disordered rock salt structure. In the DRS, the main component of the anion is oxygen, and the remainder contains F, P, S, and N (O substituents) as described above. The molar ratio of F / (P, S, and N) can be any useful value, but desirably is 1 or more up to 100, 50, 25, 20, or 15. The combination of F with any one of P, S, and N improves one or more attributes that may be different. That is, P, S, and N can be used alone or in combination depending on the desired attribute(s). 【0008】 As used herein, when a main component is specified, it means more than 50 mole % of that component, or substantially all (99% or less, readily understood from the context in which it is used). That is, the component specified as the main component is present in an amount exceeding 50% - 99%, 90, 80%, 70%, or 60% of that component. When a minor component is the specified component, it is present in an amount of less than 50% to about 1%, and the remainder is the component specified as the main component. 【0009】 This composition includes an irregular rock salt type having a cation containing lithium and at least one other metal, and an anion containing oxygen, fluorine, and one or more of phosphorus, sulfur, and nitrogen. Desirably, oxygen is the main component of the anion, and the sub-components include F and one or more of P, S, and N. Fluorine is the main component of two or more of F, S, P, and N. Exemplarily, the F / (P, S, and N) ratio is desirably at least 1 to 100, 50, 25, 10, 5, or 2. 【0010】 DRS can be used in primary and secondary lithium-ion batteries. DRS can be used with any suitable electrolyte, separator, and anode, such as those known in the art. 【Brief Description of the Drawings】 【0011】 【Figure 1】 X-ray diffraction plots of the irregular rock salt type of the present invention and the irregular rock salt type not of the present invention. 【Figure 2】 Shows the first cycle capacity and Coulomb efficiency of the half cells of the irregular rock salt type of the present invention and the irregular rock salt type not of the present invention. 【Figure 3】 Plots of the first cycle capacity and (dQ / dV) of a battery having the irregular rock salt type cathode of the present invention and the cathode of the irregular rock salt type not of the present invention. 【Figure 4】 Plots of the first cycle capacity and (dQ / dV) of a battery having the irregular rock salt type cathode of the present invention and the cathode of the irregular rock salt type not of the present invention. 【Figure 5】 Plots of the first cycle capacity and (dQ / dV) of a battery having the irregular rock salt type cathode of the present invention and the cathode of the irregular rock salt type not of the present invention. 【Figure 6】 Shows the capacity versus the number of cycles of the battery of the present invention and the battery not of the present invention. 【Figure 7】 Shows the capacity versus the number of cycles of the battery of the present invention and the battery not of the present invention. 【Figure 8】Shows the capacity with respect to the number of cycles of the battery of the present invention and the battery that is not of the present invention. 【Mode for Carrying Out the Invention】 【0012】 The following definitions apply to some of the aspects described with respect to some embodiments of the present invention. These definitions may also be extended herein. Each term is further explained and illustrated throughout the description, drawings, and examples. Any interpretation of the terms in this description shall be considered in light of the complete description, drawings, and examples presented herein. 【0013】 Unless the context clearly dictates otherwise, the singular forms "a", "an", and "the" include the plural. Thus, for example, a reference to an object can include a plurality of objects unless the context clearly dictates otherwise. 【0014】 The rate "C" refers to either the discharge current as a fraction or multiple of the "1C" current value at which a battery (substantially fully charged state) would discharge substantially completely in 1 hour, or the charge current as a fraction or multiple of the "1C" current value at which a battery (substantially fully discharged state) would charge substantially completely in 1 hour, depending on the context. 【0015】 When certain battery characteristics can vary with temperature, such characteristics are specified at 30 degrees Celsius unless the context clearly dictates otherwise. 【0016】 The ranges shown herein include their endpoints. Thus, for example, the range from 1 to 3 includes the values 1 and 3, as well as intermediate values. 【0017】 The composition and morphology (e.g., structure) of the DRS are useful for the formulation of the electrodes of an electrochemical cell. More specifically, the DRS may be used to form a cathode. A lithium-ion battery includes an electrolyte formulation having a lithium salt present in a concentration suitable for conducting lithium ions through the electrolyte formulation between the cathode and the anode during discharge and recharge operations. 【0018】 In the disordered rock salt type, both lithium and transition metals occupy the octahedral sites of the cubic close-packed lattice. In an electrochemical reaction, the diffusion of lithium proceeds by lithium hopping from one octahedral site to another via intermediate tetrahedral sites. Lithium in the intermediate tetrahedral site is in an activated state in lithium diffusion. The activated tetrahedral lithium ions share faces with the following four octahedral sites: (i) the site previously occupied by the lithium ion itself, (ii) the vacancy to which the lithium ion moves, and (iii and iv) two sites that can be occupied by lithium, transition metal, or vacancy. 【0019】 The composition may be a disordered rock salt type (DR) including those having the following formula: Li x M’ y M z O 2-(a+b) F a Z b where 1.0 < x < 1.75, 0 ≦ y < 0.55, 0.1 < z < 1, 0 ≦ (a + b) < 0.7, (b > 0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo, M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, Sn, Bi, and Sb, and Z is one or more of P, N, and S. Additional dopants such as Na and Mg that substitute for Li may be included, which may be in any useful amount, but generally up to about 10 mol% or from 5 mol% to 0.01 mol% of lithium, and such dopants are present in the DR. 【0020】 The amounts of F and Z can be the main or minor components of anions (i.e., O, F, and one or more of P, S, and N). Exemplarily, (a + b) is 0.05 to 1.5, 1, 0.95, 0.8, 0.65, 0.5. It may be desirable for a to be 0.05 to 0.25. Z may be any combination of P, N, and S, or just one of them. When two or more are present, the ratio of P, N, and S may be any useful ratio depending on the desired property. For example, when a decrease in redox potential is desired, it may be desirable to have S present. It may also be desirable for S to be the main component among P, S, and N present in the composition. 【0021】 The composition may have any desirable Li of 1 or more, but as represented by x, it may be desirable for Li to be at least 1.1, 1.15, 1.2 to 1.65, 1.5, or 1.4. 【0022】 The cationic composition may be the metals described, but as represented by M, it is desirable for at least one of the metals to include one or more of Ti, Mn, Fe, Co, V, Cr, Ni, and Cu. It may be desirable for M to include Ti and Mn. This composition may, exemplarily, be one in which M' includes Nb. When Nb is present, it may be desirable for M to include Mn. Exemplarily, M' may be Nb and M may be Mn. When Nb and Mn are present regardless of the presence or absence of other metals, they may be present in a Mn / Nb molar ratio of 1 or 2 to 200, 150, 100, 75, 50, 25, or 10. 【0023】 DRS can be prepared by any suitable method such as those known in the art for producing an irregular rock salt type. Exemplary methods are described in Patent Document 1, U.S. Patent No. 10,978,706, and ACS Appl Mater Interfaces. 2019 Oct 2;11(39):35777 - 35787, each of which is incorporated herein by reference. 【0024】 Exemplarily, the DRS preferably includes micro-sized clusters or aggregates of sub-micro-sized particles, which may be useful for increasing the capacity and energy density of the battery cathode. The micro-sized clusters are also referred to herein as secondary particles. The secondary particles preferably have an average particle size (e.g., diameter) on the micrometer scale, such as from 1 micrometer to 20 micrometers. The sub-micro-sized particles aggregate to form secondary particles. The sub-micro-sized particles are also referred to herein as primary particles. The terms "primary" and "secondary" indicate that the primary particles are formed before the secondary particles and the secondary particles are aggregates of the primary particles. The primary particles have an average particle size (e.g., diameter) on the nanometer scale, such as less than 400 nanometers. The sub-micro primary particles of the disordered rock salt-type material can provide desirable conductivity, and the micro-sized secondary particles of the disordered rock salt-type material result in a high electrode energy density. 【0025】 To form the micro-sized clusters, the precursor suspension can be milled to form a mixture of primary particles in the suspension. The precursor includes a metal compound and is selected based on the desired composition of the DRS material. One or more of the precursors can be compounds containing oxygen, fluorine, and one or more of P, S, and N (e.g., metal compounds), such as oxides, hydroxides, oxynitrides, nitrides, nitrates, sulfides, sulfates, sulfites, phosphates, phosphites, fluorides, and combinations thereof. Examples of precursors include Mn 2 O 3 , LiOH, Nb 2 O 5 , LiF, NbF 5Examples may include the like. To dope one or more of P, S, and N into the oxygen sites, at least one precursor contains one of these elements. Possible precursors for P, S, and N include the element P, S or N, metal nitrides (e.g., lithium nitride), metal nitrates, metal nitrites, metal phosphates, metal phosphides, metal phosphites, metal sulfites, metal sulfates, metal sulfides (e.g., lithium sulfide), where the metal is desirable in DRSs and their combinations. 【0026】 The precursors may be mixed in a liquid such as water in a desired amount to achieve the desired DRS stoichiometry to form a suspension. Milling can be performed by any method useful for achieving the desired particle size, examples of which include a micro media mill, ball mill, planetary mill, or attrition mill. The primary particles can have an average particle size of up to 2 micrometers, 1 micrometer, 400 nanometers (nm), 200 nm, or 100 nm. For example, the average particle size may be 50 nm, 40 nm, 30 nm, 20 nm or less. An example of a suitable micro bead mill is the Buhler PML2 mill (Buhler Group). 【0027】 Next, the suspension of precursor particles can be dried by any suitable method such as spray drying to form secondary particles. Spray drying may be performed using any known commercially available spray dryer such as a mini spray dryer such as the Buchi B-290 model. 【0028】 Next, the spray-dried precursor particles can be heated to the annealing temperature. At the annealing temperature, the precursors within the secondary particles react to form a single phase. Desirably, the temperature and time are such that the resulting DRS retains the form of the micro-sized spray-dried secondary particles. The annealing temperature may be 500 °C, 750 °C to 900 °C, 1000 °C or 1200 °C over 10 minutes, 1, 2, 3, or 5 hours to 12 or 24 hours. 【0029】 The annealing process may be carried out in any suitable atmosphere, which may be static or flowing. The annealing environment may be under a noble gas, nitrogen, air, or dry air, and combinations thereof to achieve the desired partial pressure of one or more gases. In other embodiments, the annealing conditions may be selected based on the composition of the rock-salt-type precursor, such as which metal is present. For example, manganese-based compositions can utilize the above conditions (e.g., 750 - 900 °C for 6 - 24 hours), while compositions based on other metals can have a wider, higher, or lower range of temperatures, and / or a wider, longer, or shorter range of time periods, or multiple-step annealing. 【0030】 In an alternative embodiment, instead of milling the lithium-containing precursor with other precursors and spray-drying, the lithium source may be held until the annealing step. For example, spherical secondary particles can be produced as described above, except that the precursor lacks lithium. These are then mixed with a lithium compound and annealed as described above. Mixing can be in any suitable and desirable way that minimizes the grinding of the spray-dried secondary particles, such as in a V blender. 【0031】 The DRS phase can be formed prior to milling. For example, the DRS phase can be formed by solid-state chemical methods such as solid redox reactions of oxide ions, which can employ milling of the precursor. The formed DRS phase can be milled and subsequently spray-dried, and other additives such as carbon can be added. One or more carbon precursors can include acetylene black, carbon black, carbon fiber, graphite, carbon nanotube KJ600, etc. One or more carbon precursors may be milled at a ratio where the rock-salt-type powder represents the main component and the carbon precursor represents the minor component. For example, the ratio of DRS powder to carbon precursor(s) can be 60:40 to 99:1. 【0032】 The cathode can be formed using DRS by any suitable method such as those known in the art. For example, the DRS powder may be mixed with a binder such as a polymer useful for making the cathode (e.g., a polyfluoropolymer such as polyvinylidene fluoride) and one or more solvents to form a slurry. Non-limiting examples of the one or more solvents can be aprotic polar solvents such as N-methyl-2-pyrrolidinone (NMP). Next, the slurry may be deposited on a metal current collector (e.g., stainless steel, copper, or any suitable conductive metal foil), and the solvent may be removed to form the cathode. 【0033】 Desirably, the DRS of the cathode has an average secondary particle size of 1 to 20 micrometers. Each of the secondary particles is an aggregate of primary particles. The primary particles of the DRS desirably have the average particle size described herein and may contain other particles that can be useful such as increasing the conductivity (e.g., carbon or other inorganic highly ion-conductive particles). 【0034】 The DRS cathode may be used in a rechargeable lithium-ion battery cell. The battery cell includes a cathode, an anode, a separator, and an electrolyte. The battery or battery cell may be formed in any suitable atmosphere such as those common in the art. For example, a high-purity argon atmosphere may be used to limit unwanted mixing from chemical species present in the atmosphere. 【0035】 Examples Example 1. A composition comprising an irregular rock salt type having a cation containing lithium and at least one other metal, and an anion containing oxygen and fluorine, and one or more of phosphorus, sulfur, and nitrogen. 【0036】 Example 2. The composition according to Example 1, wherein oxygen is the main component of the anion. 【0037】 Example 3. The composition according to Example 2, wherein fluorine is the main component of the fluorine and one or more of phosphorus, sulfur, and nitrogen. 【0038】 Example 4. The composition according to Example 1, wherein the molar ratio F / (P, S, and N) is 1 to 25. 【0039】 Example 5. The irregular rock salt type is represented by the following: Li x M’ y M z O 2-(a+b) F a Z b Here, 1.0 < x < 1.75, 0 ≤ y < 0.55, 0.1 < z < 1, 0 ≤ (a + b) < 0.7, (b > 0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo, M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb, and Z is one or more of P, N, and S. The composition according to Example 1. 【0040】 Example 6. The composition according to Example 5, wherein (a + b) is 0.05 to 1.5. 【0041】 Example 7. The composition according to Example 6, wherein (a + b) is 0.05 to 0.95. 【0042】 Example 8. The composition according to any one of Examples 5 to 7, wherein a is 0.05 to 0.25. 【0043】 Example 9. The composition according to any one of Examples 5 to 8, wherein Z is P, N, or S. 【0044】 Example 10. The composition according to any one of Examples 5 to 9, wherein M’ is Nb and y is greater than 0. 【0045】 Example 11. The composition according to any one of Examples 5 to 10, wherein x is 1.1 to 1.65. 【0046】 Example 12. The composition according to any one of Examples 5 to 11, wherein x is 1.15 to 1.5. 【0047】 The composition according to any one of Examples 5 to 12, wherein x is 1.2 to 1.4. 【0048】 The composition according to any one of Examples 5 to 13, wherein M contains one or more of Ti, Mn, Fe, Co, V, Cr, Ni, and Cu. 【0049】 The composition according to Example 14, wherein M contains Ti and Mn. 【0050】 Example 16. A cathode of a rechargeable battery, comprising an irregular rock salt-type powder having a cation containing lithium and one other metal, and an anion containing oxygen and fluorine, and one or more of phosphorus, sulfur, and nitrogen. 【0051】 Example 17. The irregular rock salt-type powder is represented by the following: Li x M’ y M z O 2-(a+b) F a Z b Here, 1.0 < x < 1.75, 0 ≦ y < 0.55, 0.1 < z < 1, 0 ≦ (a + b) < 0.7, (b > 0) M’ is one of Ti, Ta, Zr, W, Nb, or Mo, M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb, and Z is one or more of P, N, and S. The cathode according to Example 16. 【0052】 Example 18. The cathode according to Example 16 or 17, having a reduced anion redox voltage compared to an irregular rock salt-type cathode having no P, S, or N. 【0053】 Example 19. The cathode according to Example 17, wherein at least a part of Z contains S. 【0054】 Example 20. The cathode according to Example 19, wherein Z is composed of only S. 【0055】 Example 21. The cathode according to any one of Examples 17 to 20, wherein M' contains Nb and M contains Mn. 【0056】 Example 22. The cathode according to Example 21, wherein the molar ratio of Mn / Nb is 1 to 10. 【0057】 Example 23. The cathode according to Example 22, wherein the molar ratio of Mn / Nb is 2 to 5. 【0058】 Example 24. A lithium-ion battery comprising the cathode according to any one of Examples 16 to 23. 【0059】 Example 25. The cathode according to Example 16, wherein y is greater than 0.01. 【Examples】 【0060】 Comparative Example (Control): The disordered rock salt type is Mn 2 O 3 、Li 2 CO 3 、Nb 2 O 5 、and LiF precursor were used to synthesize in an amount aimed at realizing the disordered rock salt type represented by Li 1.31 Mn 0.4 Nb 0.1 Ti 0.19 O 1.77-x F 0.23 A x (where x is zero). The precursors were mixed in deionized water to form a suspension, which was milled using a zirconia medium in a planetary ball mill for 5 hours to form a mixture. The mixture was dried at 100 °C for 12 hours under air, and then annealed at 800 °C for 4 hours and 900 °C for 12 hours under an argon flow to obtain the disordered rock salt type (DRS). The DRS was milled with a carbon precursor (any one of acetylene black, carbon black, carbon fiber, graphite, carbon nanotube, or KJ600) at a weight ratio of 93:7 (powder to carbon). 【0061】 Example: The irregular rock salt type of the example was manufactured by the same method as above, but different dopant precursors were added in the first mixing to replace 0.01 and 0.02 moles of oxygen / fluorine present in the irregular rock salt type of the comparative example (i.e., x is 0.01 or 0.02). Phosphorus, Li 3 N, and Li 2 S were used as dopant precursors for P, N, and S dopants, respectively. 【0062】 Half-cells having an area similar to that of a coin-type cell were fabricated and electrochemically cycled between 1.5 and 4.6 V against a Li anode at 30 °C. 【0063】 The battery cells were formed in a glove box (M-Braun, O 2 and humidity content <0.1 ppm) filled with high-purity argon. The cathode was prepared by mixing the active cathode mixture with poly(vinylidene fluoride) (PVDF, Sigma Aldrich) and 1-methyl-2-pyrrolidinone (NMP, Sigma Aldrich) and conductive carbon to a ratio of active material:carbon:PVDF = 90:7:3. The resulting slurry was deposited on a stainless-steel current collector with a pipette and dried to form a composite cathode film of about 2 mg / cm 2 . For the anode, a thin Li foil (about 300 μm, Gotion) was cut to the required size. Each battery cell included a composite cathode film, a polypropylene separator (Celgard 2400), and a lithium foil anode. A lithium hexafluorophosphate (LiFP 6 ) containing electrolyte (1.0 M LiPF6 in EC / EMC (1:2 v / v)) in a mixture of additive (2 wt%) and ethylene carbonate (EC) and ethyl methyl carbonate (EMC) was used. The battery cells were sealed and cycled at 30 °C between 1.5 and 4.6 V at a C / 20 formation rate and a C / 3 cycle rate (where 1C = 300 mAh / g). 【0064】 The X-ray diffraction of the irregular rock salt type for the control and the examples is shown in FIG. 1. The doping level of the example shown in FIG. 1 corresponds to an amount where x is 0.02. The X-ray plot shows an irregular rock salt type structure. However, in the example doped with phosphorus, some residual LiF is shown, which indicates that the formation method when using phosphorus as a dopant may require different conditions (e.g., changes in temperature or milling time) to completely react LiF. 【0065】 The specific capacity and Coulombic efficiency of the first cycle of the control and the examples doped at x = 0.01 and 0.02 are shown in FIG. 2. The specific capacity and Coulombic efficiency are determined using the half-cell as described above. The results show that the specific capacity and Coulombic efficiency of the first cycle were essentially the same in the examples doped with S and N. The decrease in the specific capacity of the example doped with P is due to the presence of LiF and the incomplete formation of the irregular rock salt type. 【0066】 The voltage profiles of the first cycle of the control and the examples containing sulfur and dV / dQ (Q = capacity) are shown in FIG. 3 of the battery. The material doped with sulfur shows a lower voltage plateau on the oxygen redox plateau. Sulfur can release electrons more easily, thereby providing a more delocalized electron cloud on oxygen and making oxidation easier. Since the electrolyte does not need to have oxidation stability, a low charging voltage plateau can be an advantage. The material doped with sulfur also shows that the overvoltage (dQ / dV plot) between charge and discharge is smaller, which may enable a battery with lower impedance and better energy efficiency. The voltage profiles of the first cycle of the examples and the control doped with N and P are shown in FIGS. 4 and 5. 【0067】 The examples doped with N and P show improved long-term cycle life compared to the control (F-doped only). (See FIGS. 6-8). However, the samples doped with S show lower cycle performance, which may be related to a greater contribution of oxygen redox capacity. In other words, as the capacity contributed by oxygen in the doped material becomes larger (compared to the control), the cycle life will decrease. However, since oxygen redox occurs at a lower potential in the samples doped with S, the cycle performance of the samples doped with S can be improved by lowering the upper voltage cutoff.

Claims

[Claim 1] A composition comprising an irregular rock salt type having a cation containing lithium and at least one other metal, and anions containing oxygen and fluorine, as well as one or more of phosphorus, sulfur, and nitrogen. [Claim 2] The composition according to claim 1, wherein oxygen is the main component of the anion. [Claim 3] The composition according to claim 2, wherein fluorine is one or more main components selected from fluorine, phosphorus, sulfur, and nitrogen. [Claim 4] The composition according to claim 1, wherein the molar ratio F / (P, S, and N) is 1 to 25. [Claim 5] The aforementioned irregular rock salt type is represented as follows: Li ｘ M' ｙ M ｚ O ２－（ａ＋ｂ） F ａ Z ｂ The composition according to claim 1, where 1.0 < x < 1.75, 0 ≤ y < 0.55, 0.1 < z < 1, 0 ≤ (a + b) < 0.7, (b > 0) M' is one of Ti, Ta, Zr, W, Nb, or Mo, M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb, and Z is one or more of P, N, and S. [Claim 6] The composition according to claim 5, wherein a is 0.05 to 0.

25. [Claim 7] The composition according to claim 5, wherein x is 1.1 to 1.

65. [Claim 8] The composition according to claim 5, wherein M comprises one or more of Ti, Mn, Fe, Co, V, Cr, Ni, and Cu. [Claim 9] A cathode for a rechargeable battery, comprising an irregular rock salt type powder having cations comprising lithium and one other metal, and anions comprising oxygen and fluorine, and one or more of phosphorus, sulfur, and nitrogen. [Claim 10] The aforementioned irregular rock salt type powder is represented as follows: Li ｘ M' ｙ M ｚ O ２－（ａ＋ｂ） F ａ Z ｂ Herein, 1.0 < x < 1.75, 0 ≤ y < 0.55, 0.1 < z < 1, 0 ≤ (a + b) < 0.7, (b > 0) M' is one of Ti, Ta, Zr, W, Nb, or Mo, M is one or more of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Al, Zr, Y, Mo, Ru, Rh, and Sb, and Z is one or more of P, N, and S, the cathode according to claim 9. [Claim 11] The cathode according to claim 9 or 10, wherein the cathode has a reduced anion redox voltage compared to an irregular rock salt type cathode that does not have P, S, or N. [Claim 12] The cathode according to claim 11, wherein at least a portion of Z includes S. [Claim 13] The cathode according to claim 10, wherein M' includes Nb and M includes Mn. [Claim 14] The cathode according to claim 13, wherein the molar ratio Mn / Nb is 1 to 10. [Claim 15] A lithium-ion battery comprising the cathode described in Claim 11.

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