Lithium spinel-type manganese oxide, its manufacturing method, and its uses

Abstract

To provide a positive electrode material including a spinel-type lithium manganese oxide having excellent charge / discharge characteristics and output characteristics at high temperatures, and a lithium secondary battery having excellent charge / discharge characteristics and output characteristics at high temperatures.SOLUTION: A positive electrode material includes a spinel-type lithium manganese oxide having a surface on which a phosphate and at least one metal element selected from aluminum, magnesium, zinc, nickel, cobalt, iron and calcium are contained and which is represented by the chemical formula Li1+XMn2-X-YMgYO4 (X and Y satisfy 0.02≤X≤0.10 and 0.05≤Y≤0.30, respectively), and which has a phosphorus / manganese molar ratio of 0.001 or more and 0.1 or less, and there is also provided a usage thereof.SELECTED DRAWING: None

Description

[Technical Field]

[0001] This invention relates to spinel-type lithium manganese oxide, a method for producing the same, and its applications, and more specifically, to spinel-type lithium manganese oxide with a phosphate deposit on its surface, a method for producing the same, and a lithium secondary battery using the same as an electrode. [Background technology]

[0002] Lithium-ion batteries have a higher energy density compared to other types of batteries, making them widely used as batteries for portable devices. Recently, their application to large-scale, high-capacity, and high-output applications, such as stationary and automotive use, is also progressing. Research is underway to further improve performance, including applications that have already been partially commercialized.

[0003] Currently, the positive electrode material for lithium secondary batteries mainly uses cobalt-based materials (LiCoO2) for small consumer batteries such as those in mobile phones, while nickel-based materials (LiNi) are used for stationary and automotive applications. 0.8 Co 0.15 Al 0.05 O2) and nickel-cobalt-manganese ternary materials (LiNi 0.5 Co 0.2 Mn 0.3 O2, etc., is the main material used. However, cobalt and nickel raw materials are scarce and expensive, and the output characteristics are not very high.

[0004] On the other hand, spinel-type lithium manganese oxide, a manganese-based material, is suitable for large batteries and applications requiring high power output because its raw material, manganese, is abundant and inexpensive, and it also has excellent power output characteristics and safety.

[0005] However, spinel-type lithium manganate has problems with high-temperature stability, that is, charge-discharge characteristics at high temperatures, particularly charge-discharge characteristics with a carbon counter electrode and storage characteristics, and solving this problem has been desired. For example, in Patent Document 1 and Patent Document 2, spinel-type lithium manganate containing a phosphate has been proposed in both cases, but there is still room for improvement in charge-discharge characteristics at high temperatures, particularly charge-discharge characteristics with a carbon counter electrode.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide spinel-type lithium manganate having excellent charge-discharge characteristics at high temperatures, particularly charge-discharge characteristics with a carbon counter electrode and output characteristics, and further to provide a lithium secondary battery using spinel-type lithium manganate as a positive electrode.

Means for Solving the Problems

[0008] The inventors of the present invention have intensively studied spinel-type lithium manganate. As a result, they have found that the present invention summarized below can achieve the above-described problems. That is, the present invention contains a phosphate and at least one metal element selected from aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on the surface, and has the chemical formula Li 1+X Mn 2-X-Y Mg YThis invention relates to spinel-type lithium manganate represented by O4 (wherein X and Y are 0.02 ≤ X ≤ 0.10 and 0.05 ≤ Y ≤ 0.30, respectively), characterized in that the phosphorus / manganese molar ratio is 0.001 or more and 0.1 or less, as well as a method for producing the same, and its uses. [Effects of the Invention]

[0009] When the spinel-type lithium manganese oxide of the present invention is used as a cathode material for lithium secondary batteries, it is possible to provide lithium secondary batteries with improved charge-discharge characteristics at high temperatures, particularly carbon counter electrode charge-discharge characteristics, and superior output characteristics compared to conventional materials. [Brief explanation of the drawing]

[0010] [Figure 1] This is a SEM-EDX image of the particle surface of phosphate-containing Mn3O4 obtained in Reference Example 1. [Figure 2] This is the XRD pattern of phosphate-containing spinel-type lithium manganate obtained in Reference Example 1. [Figure 3] This is an SEM-EDX image of the particle surface of phosphate-containing spinel-type lithium manganate obtained in Reference Example 1. [Modes for carrying out the invention]

[0011] The present invention will be described in detail below.

[0012] The spinel-type lithium manganate of the present invention contains a phosphate and at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on its surface. By containing a phosphate and at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on its surface, it is possible to obtain excellent charge-discharge characteristics at high temperatures when used as a positive electrode active material for lithium secondary batteries. At high temperatures, the charge-discharge cycle characteristics deteriorate due to the leaching of manganese by the reaction of the spinel-type lithium manganate with hydrogen fluoride, which is present in small amounts in the electrolyte of the lithium secondary battery. The presence of a phosphate and metal element on the surface of the spinel-type lithium manganate traps the hydrogen fluoride in the electrolyte, suppressing manganese leaching and making it possible to suppress the decrease in capacity during charge-discharge at high temperatures.

[0013] The spinel-type lithium manganate of the present invention has the chemical formula Li 1+X Mn 2-X-Y Mg Y O4 is represented by the formula O4 (where X and Y are 0.02 ≤ X ≤ 0.10 and 0.05 ≤ Y ≤ 0.30, respectively). If the value of X is less than 0.02, capacity degradation is likely to occur during charging and discharging at high temperatures, and if it exceeds 0.10, sufficient charge and discharge capacity cannot be obtained. Similarly, if the value of Y is less than 0.05, capacity degradation is likely to occur during charging and discharging at high temperatures, and if it exceeds 0.30, sufficient charge and discharge capacity cannot be obtained. X and Y of spinel-type lithium manganese oxide can be determined from compositional analysis. Examples of such methods include inductively coupled plasma emission spectrometry and atomic absorption spectrometry.

[0014] The spinel-type lithium manganate of the present invention has a phosphorus / manganese molar ratio of 0.001 or more and 0.1 or less. A phosphorus / manganese molar ratio of 0.001 or more and 0.1 or less allows for excellent charge / discharge characteristics at high temperatures and increased charge / discharge capacity when used as a positive electrode active material in lithium secondary batteries. A phosphorus / manganese molar ratio of less than 0.001 is undesirable because it tends to lead to a significant decrease in capacity during charge / discharge at high temperatures. A ratio greater than 0.1 is also undesirable because it results in a smaller charge / discharge capacity. A phosphorus / manganese molar ratio of 0.001 or more and 0.08 or less is preferred, and 0.005 or more and 0.05 or less is more preferred.

[0015] The spinel-type lithium manganate of the present invention preferably contains at least Li3PO4 as a phosphate. The phosphate used in synthesizing the spinel-type lithium manganate of the present invention is a phosphate containing at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium. When the phosphate raw material, manganese raw material, and lithium raw material are mixed and calcined, the phosphate reacts with the lithium raw material to produce Li3PO4. The produced Li3PO4 exists only on the surface of the spinel-type lithium manganate. Furthermore, the spinel-type lithium manganate of the present invention may also have phosphates containing at least one metal element other than Li3PO4 from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on its surface.

[0016] The spinel-type lithium manganate of the present invention, when used as a positive electrode active material in lithium secondary batteries, enables the acquisition of excellent charge-discharge characteristics at high temperatures and excellent output characteristics, resulting in a BET specific surface area of ​​0.3 m². 2 / g or more 1.5m 2 It is preferable that it be less than or equal to / g, and 0.3m 2 / g or more 0.6m 2 Less than / g is preferable.

[0017] When the spinel-type lithium manganate of the present invention is used as a positive electrode active material of a lithium secondary battery, excellent output characteristics can be obtained, and the filling property of the positive electrode mixture can be improved. Therefore, the average particle diameter of the secondary particles is preferably 4 μm or more and 8 μm or less, and more preferably 5 μm or more and 7 μm or less.

[0018] When the spinel-type lithium manganate of the present invention is used as a positive electrode active material of a lithium secondary battery, its crystallinity is increased, the elution of manganese is suppressed, the crystal structure change accompanying charge and discharge is suppressed, and excellent charge and discharge characteristics at high temperatures can be obtained. Therefore, the half-value width of the (400) plane by XRD measurement is preferably 0.005 or more and 0.06 or less, and more preferably 0.005 or more and 0.05 or less.

[0019] The measurement method of the half-value width was performed according to <Measurement of the half-value width by XRD> in the examples. In order to correct the error of the measuring device, after measuring a standard substance in advance, the half-value width of the standard substance was subtracted from the half-value width of the spinel-type lithium manganate to calculate it.

[0020] When the spinel-type lithium manganate of the present invention is used as a positive electrode active material of a lithium secondary battery, its composition is made uniform, and excellent charge and discharge characteristics at high temperatures can be obtained. Therefore, the relative standard deviation of the secondary particle diameter is preferably 60% or less, and more preferably 40% or less.

[0021] When the spinel-type lithium manganate of the present invention is used as a positive electrode active material of a lithium secondary battery, in order to obtain excellent charge and discharge characteristics at high temperatures, the average diameter of the primary particles is 0.5 μm or more and preferably 3.0 μm or less, and more preferably 1.0 μm or more and 2.5 μm or less.

[0022] The spinel-type lithium manganese oxide of the present invention is preferably such that the SO4 content is 0.3 wt% to 1.0 wt%, and more preferably 0.4 wt% to less than 0.7 wt%, in order to increase the charge-discharge capacity when used as a positive electrode active material for lithium secondary batteries and to obtain excellent charge-discharge characteristics at high temperatures.

[0023] The spinel-type lithium manganate of the present invention has high crystallinity and, when used as a positive electrode active material for lithium secondary batteries, it is preferable that the Na content be 3,000 wtppm or less, and more preferably 1,000 wtppm or less, in order to obtain excellent charge-discharge characteristics at high temperatures.

[0024] Next, the method for producing spinel-type lithium manganate according to the present invention will be described.

[0025] The spinel-type lithium manganate of the present invention is obtained by mixing a manganese raw material containing phosphorus and at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on its surface, along with a lithium raw material and a magnesium raw material, and then calcining and crushing the mixture at 850 to 950°C in air or in a high-concentration oxygen atmosphere (including a pure oxygen atmosphere). Alternatively, it can also be obtained by mixing a manganese raw material, a lithium raw material, a magnesium raw material and a phosphoric acid raw material containing at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium phosphates, and then calcining and crushing the mixture at 850 to 950°C in air or in a high-concentration oxygen atmosphere (including a pure oxygen atmosphere).

[0026] There are no particular restrictions on the manganese raw material, but crystallized Mn3O4, electrolytic MnO2, or Mn2O3 obtained by calcining crystallized Mn3O4 or electrolytic MnO2 are preferred because they allow for high packing when synthesizing spinel-type lithium manganate.

[0027] A manganese raw material containing phosphorus and at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium on its surface can be obtained by preparing a slurry containing Mn3O4 by crystallization, MnO2 by electrolysis, etc., and adding an alkaline aqueous phosphate solution and an acidic aqueous solution containing at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium to the slurry.

[0028] There are no particular restrictions on the lithium raw materials; for example, lithium carbonate, lithium hydroxide, lithium nitrate, lithium chloride, lithium iodide, lithium oxalate, etc., are examples, but the material is not limited to these.

[0029] There are no particular restrictions on the magnesium raw materials; for example, magnesium hydroxide, magnesium oxide, magnesium carbonate, etc., are examples, but the material is not limited to these.

[0030] Examples of phosphoric acid raw materials containing at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium phosphates include AlPO4, Al(H2PO4)3, Mg3(PO4)2, Mg(H2PO4)2, Zn3(PO4)2, Ni3(PO4)2, Ni2P2O7, Co3(PO4)2, Fe3(PO4)2, Ca3(PO4)2, CaHPO4, CaH2P2O7, and the like.

[0031] Examples of methods for mixing manganese raw materials, lithium raw materials, and magnesium raw materials, or methods for mixing manganese raw materials, lithium raw materials, magnesium raw materials, and phosphoric acid raw materials, include dry mixing and wet mixing.

[0032] The calcination process for obtaining spinel-type lithium manganate according to the present invention is carried out in air or a high-concentration oxygen atmosphere (including a pure oxygen atmosphere), i.e., in an oxygen atmosphere with an oxygen content of 18 to 100 vol%, at 850 to 950°C. Below 850°C, the BET specific surface area of ​​spinel-type lithium manganate tends to increase, and above 950°C, the oxygen deficiency of spinel-type lithium manganate increases, resulting in a decrease in charge-discharge cycle characteristics when used as a positive electrode active material for lithium secondary batteries. Calcination is preferably carried out at 900 to 930°C.

[0033] Since spinel-type lithium manganate tends to solidify secondary particles during calcination, it is crushed to obtain the desired particle size. The crushing method is preferably done by shear force to suppress the generation of fine powder and the increase in BET specific surface area.

[0034] After crushing the spinel-type lithium manganate, it is preferable to pass it through a sieve to remove coarse particles that exceed the thickness of the positive electrode. The sieve opening is preferably 50 μm or less.

[0035] By using the phosphate-containing spinel-type lithium manganate of the present invention as the positive electrode of a lithium secondary battery, it becomes possible to construct a lithium secondary battery that exhibits excellent charge-discharge cycle characteristics at high temperatures and superior output characteristics, which were not possible with conventional methods.

[0036] There are no particular restrictions on the composition of lithium secondary batteries other than the positive electrode, but the negative electrode should be made of a material that absorbs and desorbs Li, such as carbon-based materials, tin oxide-based materials, or Li4Ti5O 12 Examples of materials that form alloys with SiO and Li include silicon-based materials and aluminum-based materials. Examples of materials that form alloys with Li include silicon-based materials and aluminum-based materials. Examples of electrolytes include organic electrolytes obtained by dissolving Li salts and various additives in an organic solvent, Li ion conductive solid electrolytes, and combinations thereof. [Examples]

[0037] Next, the present invention will be described with reference to specific embodiments, but the present invention is not limited to these embodiments.

[0038] <Battery performance test> (1) Initial capacity measurement, lithium counter electrode charge / discharge cycle test 25 mg of spinel-type lithium manganate obtained in each example and 12.5 mg of conductive binder (product name: TAB-2, manufactured by Hosen) were mixed using an agate mortar. The resulting mixture was ground at a rate of 2 tons / cm² through a 16 mm diameter SUS mesh (SUS316). 2 The material was uniaxially pressed to form disc-shaped pellets, which were then dried under reduced pressure at 150°C for 2 hours to form the positive electrode.

[0039] A metallic lithium is used as the negative electrode, and 1 mol / dm³ of LiPF6 is added to a solvent consisting of ethylene carbonate and dimethyl carbonate in a volume ratio of 1:2. 3 A battery was constructed using a dissolved solution as the electrolyte, a polyethylene sheet (product name: Cellguard, manufactured by Polypore) as the separator, and a model cell (product name: Tomcell, manufactured by Nippon Tomcell Co., Ltd.) as the cell.

[0040] Using the fabricated battery, at 60°C, the cell voltage was between 4.3V and 3.0V, and the current density was 0.4mA / cm². 2 At a constant current, one charge-discharge cycle was performed, and the charge capacity of the first cycle was taken as the initial capacity. Subsequently, at 60°C, with a cell voltage between 4.3V and 3.0V, a current density of 1.3mA / cm² was measured. 2 The lithium counter electrode charge-discharge cycle characteristics were determined from the ratio of the discharge capacity at the 50th cycle to that at the 1st cycle, after performing 50 charge-discharge cycles at a constant current.

[0041] (2) Carbon counter electrode charge-discharge cycle test As the negative electrode, a spherulite graphite sheet (Hosen TSG-A1, nominal capacity 1.6mAh / cm²) is used. 2 After punching out a diameter of 16.156 mm, the material was processed at 3 tons / cm². 2Aside from using a uniaxially pressed material, adjusting the amount of positive electrode active material so that the negative electrode / positive electrode capacity ratio was 1.2, using a polypropylene gasket, and using a CR2032 type coin cell, the battery was manufactured using the same method as the lithium counter electrode charge-discharge cycle test.

[0042] Using the fabricated battery, at 24°C, with cell voltages between 4.25V and 3.0V, a current density of 0.14mA / cm² was obtained. 2 A constant current / constant voltage charging-constant current discharging cycle was performed. Then, at 24°C, with cell voltages between 4.25V and 3.0V, the current density was 0.28mA / cm². 2 One cycle of constant-current-constant-voltage charging followed by constant-current-discharging was performed, and the discharge capacity was defined as the battery capacity. Next, at 60°C, with cell voltages between 4.25V and 3.0V, 50 cycles of constant-current-constant-voltage charging followed by constant-current-discharging were performed at a current density equal to the 1-hour discharge rate relative to the battery capacity. The carbon counter electrode charge-discharge cycle characteristics were determined from the ratio of the discharge capacity of the 50th cycle to that of the 1st cycle. The termination condition for constant-voltage charging was defined as the point when the charging current decreased to 1 / 10 of the constant-voltage charging current.

[0043] (3) Output characteristics test The battery was fabricated using the same method as the lithium counter electrode charge-discharge cycle test, except that 10 mg of spinel-type lithium manganese oxide and 10 mg of conductive binder (product name: TAB-2, manufactured by Hosen) were used.

[0044] Using the fabricated battery, at 24°C, with cell voltages between 4.3V and 3.0V, a current density of 0.15mA / cm² was obtained. 2 After performing 3 charge / discharge cycles with a constant current, the charging current was 0.15 mA / cm². 2 , discharge current 5mA / cm 2 Three charge-discharge cycles were performed at a constant current. Current density: 5 mA / cm² 2 Discharge capacity and current density of 0.15 mA / cm² in the third cycle. 2 The output characteristics were determined from the ratio of the discharge capacity in the third cycle.

[0045] <Measurement of Composition Analysis, SO4 Content, and Na Content> For the composition, phosphorus / manganese molar ratio, SO4 content, and Na content of the spinel-type lithium manganate prepared in the examples and comparative examples, after dissolving the spinel-type lithium manganate in an aqueous hydrochloric acid-hydrogen peroxide mixed solution, it was analyzed with an inductively coupled plasma optical emission spectrometer (trade name: ICP-AES, manufactured by PerkinElmer Japan).

[0046] <Measurement of the Distribution State of Phosphorus and Metal Elements and the Average Particle Size of Primary Particles of Lithium Manganate> Regarding the spinel-type lithium manganate prepared in the examples and comparative examples, the distribution state of phosphorus and metal elements and the measurement of the average particle size of primary particles were carried out with a scanning electron microscope (trade name: JSM-IT500, manufactured by JEOL Ltd.).

[0047] <Measurement of the Half-Width by XRD> Regarding the spinel-type lithium manganate prepared in the examples and comparative examples, the measurement of the half-width by XRD was carried out with a powder XRD measurement device (trade name: Ultima IV, manufactured by Rigaku). The measurement conditions were as follows.

[0048] · Target: Cu · Output: 1.6 kW (40 mA - 40 kV) · Filter: Kβ filter · Divergence slit: 1° · Divergence vertical limit slit: 10 mm · Scattering slit: Open · Receiving slit; Open · Scanning mode: Continuous · Scan speed: 4.000° / min · Sampling width: 0.04° (2θ / θ) · Integration times: 1 time · Measurement range: 10 - 90° (2θ / θ) The obtained XRD data of the spinel-type lithium manganate were analyzed using the analysis software (PDXL2) attached to the powder X-ray diffraction measurement device, and the integral width of the (400) plane near 2θ = 44° was obtained.

[0049] In addition, in order to correct the error of the measuring device, the XRD standard substance (α-type quartz powder manufactured by NIST) was measured in advance, and the half-value width was obtained by subtracting the integrated width of the standard substance from the integrated width of spinel-type lithium manganate.

[0050] <Measurement of BET specific surface area> 1.0 g of the sample was placed in a glass cell for BET specific surface area measurement, and dehydration treatment was carried out at 150 °C for 30 minutes under a nitrogen stream to remove the moisture adhering to the powder particles.

[0051] The treated sample was measured for the BET specific surface area by the one-point method using a BET measuring device (trade name: MiCROMERITICS DeSorbIII, manufactured by Shimadzu Corporation) and a mixed gas of 30% nitrogen - 70% helium as the adsorption gas.

[0052] <Measurement of average particle diameter and relative standard deviation of secondary particles of lithium manganate> Using a particle size distribution measuring device (trade name: MT3000II series, manufactured by MicrotracBEL), the average particle diameter (D 50 ) and the standard deviation of the particle diameter were measured.

[0053] Based on the following formula, the relative standard deviation of the secondary particle diameter was obtained from the measured average particle diameter and standard deviation of the secondary particles.

[0054] Relative standard deviation (%) = (standard deviation of particle diameter) / (average particle diameter) × 100 Reference Example 1 Air was blown into pure water at 60 °C while stirring. While keeping the redox potential of the pure water constant at 100 mV with respect to the hydrogen electrode, a 2 mol / L manganese sulfate aqueous solution and a 20 wt% sodium hydroxide aqueous solution were continuously added to the pure water, respectively. Then, the obtained slurry was filtered, washed, and dried to obtain Mn3O4 with an average particle diameter of 3.8 μm.

[0055] A slurry was prepared by adding 2.5 L of pure water to 100 g of Mn3O4. While maintaining the slurry at 23°C and stirring, 300 g of 7.8 mmol / kg aluminum sulfate and 300 g of 31.3 mmol / kg diammonium phosphate were continuously and simultaneously added over 5 hours. The slurry was then filtered, washed with water, and dried at 110°C. The resulting material had an aluminum / manganese molar ratio and a phosphorus / manganese molar ratio of 0.0038. Figure 1 shows an SEM-EDS image of the particle surface. The SEM-EDS image revealed that aluminum and phosphorus were uniformly present on the particle surface. Furthermore, the XRD pattern observed was only Mn3O4, JCPDS No. 24-734. Therefore, the obtained material was considered to be Mn3O4 with amorphous aluminum phosphate uniformly supported on its surface.

[0056] 78.00 g of aluminum phosphate-supported Mn3O4, 22.00 g of Li2CO3 with an average particle size of 3 μm, and 1.77 g of Mg(OH)2 (manufactured by Wako Pure Chemical Industries, average particle size of 0.07 μm) were dry-mixed and calcined in a box-type furnace at 900°C for 6 hours while circulating air at a rate of 5 L / min, and then cooled to room temperature. The heating rate was 100°C / hr, and the cooling rate was 20°C / hr from 900°C to 600°C, and 100°C / hr from 600°C to room temperature. The obtained phosphate-containing spinel-type lithium manganate was crushed using a powerful small-scale pulverizer (product name: ForceMill, manufactured by Osaka Chemical) to obtain phosphate-containing spinel-type lithium manganate.

[0057] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.08 Mn 1.86 Mg 0.06The result was O4. Figure 2 shows the XRD pattern of the obtained phosphate-containing spinel-type lithium manganate. The XRD pattern was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). Figure 3 shows the SEM-EDS image of the surface of the phosphate-containing spinel-type lithium manganate particles. Aluminum and phosphorus were observed on the surface. Table 1 shows the phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of secondary particle diameter, average particle diameter of lithium manganate primary particles, SO4 content, and Na content, and Table 2 shows the battery performance.

[0058] [Table 1]

[0059] [Table 2]

[0060] Example 2 Lithium manganese phosphate containing phosphate was obtained using the same method as in Reference Example 1, except that the concentration of aluminum sulfate was 15.6 mmol / kg, the concentration of diammonium phosphate was 62.6 mmol / kg, and the amount of Li2CO3 mixed was 22.17 g.

[0061] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.07 Mn 1.87 Mg 0.06The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of aluminum and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0062] Example 3 A phosphate-containing spinel-type lithium manganate was obtained using the same method as in Example 2, except that the calcination temperature was set to 930°C.

[0063] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.07 Mn 1.87 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of aluminum and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0064] Reference example 2 Lithium manganese phosphate containing phosphate was obtained by the same method as in Reference Example 1, except that the concentration of aluminum sulfate was 3.9 mmol / kg, the concentration of diammonium phosphate was 15.7 mmol / kg, the amount of Li2CO3 mixed was 22.23 g, and the calcination temperature was 930°C.

[0065] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.09 Mn 1.85 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of aluminum and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0066] Example 5 Pure water at 60°C was stirred while air was blown into it. While maintaining a constant oxidation-reduction potential of 100 mV relative to the hydrogen electrode, a 2 mol / L manganese sulfate aqueous solution and a 20 wt% sodium hydroxide aqueous solution were continuously added to the pure water, respectively. The resulting slurry was then filtered, washed, and dried to obtain Mn3O4 with an average particle size of 3.8 μm.

[0067] 78.00 g of Mn3O4, 22.18 g of Li2CO3 with an average particle size of 3 μm, 1.77 g of Mg(OH)2 (manufactured by Wako Pure Chemical Industries, average particle size of 0.07 μm), and 1.61 g of Mg3(PO4)2·8H2O (manufactured by Kishida Chemical) were dry-mixed and calcined in a box-type furnace at 900°C for 6 hours while circulating air at a rate of 5 L / min, and then cooled to room temperature. The heating rate was 100°C / hr, and the cooling rate was 20°C / hr from 900°C to 600°C, and 100°C / hr from 600°C to room temperature. The obtained phosphate-containing spinel-type lithium manganate was crushed using a powerful small-scale pulverizer (product name: ForceMill, manufactured by Osaka Chemical) to obtain phosphate-containing spinel-type lithium manganate.

[0068] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.06 Mn1.87 Mg 0.07 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of magnesium and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0069] Example 6 Lithium spinel-type manganate containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.44 g and 1.82 g of Zn3(PO4)2·4H2O (manufactured by Kishida Chemical) was used as the phosphate.

[0070] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.08 Mn 1.86 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of zinc and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0071] Example 7 Lithium spinel-type manganese oxide containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.36 g and an aqueous solution was used in which 1.14 g of Mg(H2PO4)2·4H2O (manufactured by Junsei Chemical) was dissolved in 5 g of pure water as the phosphate.

[0072] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.06 Mn 1.87 Mg 0.07 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of magnesium and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0073] Example 8 Lithium manganese phosphate containing spinel was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.36 g, 0.83 g of Al(H2PO4)3 (manufactured by Junsei Chemical) was used as the phosphate, and the calcination temperature was 930°C.

[0074] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.07 Mn 1.87 Mg 0.06The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of aluminum and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0075] Example 9 Lithium spinel-type manganate containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.18 g and 1.33 g of CaHPO4·2H2O (manufactured by Wako Pure Chemical Industries) was used as the phosphate.

[0076] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.08 Mn 1.86 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of calcium and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0077] Example 10 Lithium spinel-type manganate containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.44 g and 0.86 g of CaH2P2O7 (manufactured by Wako Pure Chemical Industries) was used as the phosphate.

[0078] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.08 Mn 1.86 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of calcium and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0079] Example 11 Lithium spinel-type manganate containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.18 g and 2.11 g of Co3(PO4)2·8H2O (manufactured by Wako Pure Chemical Industries) was used as the phosphate.

[0080] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.10 Mn 1.84 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of cobalt and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0081] Example 12 Lithium spinel-type manganate containing phosphate was obtained in the same manner as in Example 5, except that the amount of Li2CO3 mixed was 22.20 g and 1.60 g of Ni2P2O7·7H2O (manufactured by Wako Pure Chemical Industries) was used as the phosphate.

[0082] The composition of the obtained phosphate-containing spinel-type lithium manganate is Li 1.10 Mn 1.84 Mg 0.06 The result was O4. Furthermore, XRD measurements revealed that the obtained phosphate-containing spinel-type lithium manganate was a mixed phase of JCPDS No. 35-782 (LiMn2O4) and No. 25-1030 (Li3PO4). In addition, SEM-EDS measurements of the surface of the phosphate-containing spinel-type lithium manganate particles revealed the presence of nickel and phosphorus on the particle surface. The phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of the lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of the secondary particle diameter, average particle diameter of the lithium manganate primary particles, SO4 content, and Na content are shown in Table 1, and the battery performance is shown in Table 2.

[0083] Comparative Example 1 Lithium spinel-type manganate was obtained in the same manner as in Example 5, except that phosphate was not added and the amount of Li2CO3 mixed was 21.21 g.

[0084] The composition of the obtained spinel-type lithium manganate is Li 1.07 Mn 1.87 Mg 0.06 The material was O4. Furthermore, XRD measurement revealed that the obtained spinel-type lithium manganate was JCPDS No. 35-782 (LiMn2O4) single phase. Table 1 shows the phosphorus / manganese molar ratio, BET specific surface area, average particle diameter of lithium manganate secondary particles, full width at half maximum of the (400) plane measured by XRD, relative standard deviation of secondary particle diameter, average particle diameter of lithium manganate primary particles, SO4 content, and Na content, and Table 2 shows the battery performance. From Table 2, it became clear that Comparative Example 1 had inferior carbon counter electrode cycle characteristics compared to the example. [Industrial applicability]

[0085] The phosphate-containing spinel-type lithium manganate of the present invention contains a specific phosphate and at least one metal element from among aluminum, magnesium, zinc, nickel, cobalt, iron, and calcium, and has a full width at half maximum, BET specific surface area, and secondary particle diameter as measured by XRD. Therefore, it can be used as a positive electrode active material for lithium secondary batteries that has excellent charge-discharge characteristics at high temperatures, especially for carbon counter electrodes, and also has excellent output characteristics.

Claims

1. The surface contains phosphate and at least one metallic element from among aluminum, magnesium, and zinc, and the chemical formula is Li １＋Ｘ Mn ２－Ｘ－Ｙ Mg Ｙ O ４ A positive electrode material for a battery with a carbon negative electrode, comprising spinel-type lithium manganese oxide represented by the formula (wherein X and Y are 0.02 ≤ X ≤ 0.10 and 0.05 ≤ Y ≤ 0.30, respectively), characterized in that the phosphorus / manganese molar ratio is 0.0074 or more and 0.0080 or less.

2. As phosphate, at least Li ３ PO ４ The positive electrode material according to claim 1, comprising spinel-type lithium manganate, characterized by containing the following:

3. BET specific surface area is 0.3 m² ２ / g or more 1.5m ２ A positive electrode material according to claim 1 or 2, comprising spinel-type lithium manganate characterized by being less than or equal to / g.

4. A positive electrode material according to any one of claims 1 to 3, comprising spinel-type lithium manganate, characterized in that the average particle diameter of the secondary particles is 4 μm or more and 8 μm or less.

5. A cathode material according to any one of claims 1 to 4, comprising spinel-type lithium manganate, characterized in that the (400) plane full width at half maximum measured by XRD is 0.005 or more and 0.06 or less.

6. A positive electrode material according to any one of claims 1 to 5, comprising spinel-type lithium manganate, characterized in that the relative standard deviation of the secondary particle size is 60% or less.

7. A cathode material according to any one of claims 1 to 6, comprising spinel-type lithium manganate, characterized in that the average diameter of primary particles observed by SEM is 0.5 μm or more and 3.0 μm or less.

8. SO ４ The cathode material according to any one of claims 1 to 7, comprising spinel-type lithium manganate, wherein the content of SO is 0.3 wt% or more and 1.0 wt% or less.

9. A positive electrode material according to any one of claims 1 to 8, comprising spinel-type lithium manganate, characterized in that the Na content is 3,000 wt ppm or less.

10. An electrode characterized by comprising the positive electrode material described in any one of claims 1 to 9.

11. A lithium secondary battery characterized by using the electrode described in claim 10 as the positive electrode, wherein the carbon negative electrode cycle characteristics are 83.9% or more and 86.9% or less.

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