Positive electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Abstract

This positive electrode active material for a non-aqueous electrolyte secondary battery contains a lithium transition metal complex oxide capable of occluding and releasing Li, and contains SrMnO3 in the interior or exterior of secondary particles of the lithium transition metal complex oxide.

Description

[Technical Field]

[0001] The present disclosure relates to a positive electrode active material for a non-aqueous electrolyte secondary battery, and a non-aqueous electrolyte secondary battery using the positive electrode active material. [Background technology]

[0002] The positive electrode active material contained in a non-aqueous electrolyte secondary battery may undergo a side reaction with the electrolyte, resulting in a decrease in battery capacity due to repeated charge and discharge. This tendency is particularly pronounced in batteries that use a positive electrode active material with a high energy density. Patent Document 1 discloses a positive electrode active material in which the surface of a spinel-type lithium manganese oxide is coated with nanoparticles of olivine-type lithium metal phosphate oxide or the like. Patent Document 2 also discloses a positive electrode active material in which fine particles of an oxide of a metal element such as Zr are attached to the surface of a lithium-containing composite oxide. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-191540 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-138197 Summary of the Invention

[0004] Secondary batteries using the positive electrode active materials disclosed in Patent Documents 1 and 2 have improved durability but lower battery capacity compared to secondary batteries using uncoated positive electrode active materials. The positive electrode active materials disclosed in Patent Documents 1 and 2 still have room for improvement in terms of battery capacity.

[0005] A positive electrode active material for a non-aqueous electrolyte secondary battery according to one embodiment of the present disclosure includes a lithium transition metal composite oxide capable of absorbing and desorbing Li, and SrMnO3 is contained inside or outside secondary particles of the lithium transition metal composite oxide.

[0006] A non-aqueous electrolyte secondary battery according to one embodiment of the present disclosure includes a positive electrode containing the above-described positive electrode active material for a non-aqueous electrolyte secondary battery, a negative electrode, and an electrolyte.

[0007] According to one aspect of the present disclosure, the durability and battery capacity of a secondary battery can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a longitudinal cross-sectional view of a cylindrical secondary battery as an example of an embodiment. [Figure 2] FIG. 2 shows the X-ray diffraction patterns of Example 2 and Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0009] A positive electrode active material in which the surface of a lithium transition metal composite oxide is coated with an oxide or the like can suppress side reactions such as electrolyte decomposition and elution of transition metals from the positive electrode active material during battery charge and discharge. However, the coating can impede lithium ion migration, resulting in a decrease in battery capacity. After extensive research into this issue, the present inventors have found that the durability and battery capacity of secondary batteries can be improved by using a positive electrode active material in which SrMnO3 is present inside or outside the secondary particles of a lithium transition metal composite oxide. It is believed that SrMnO3 suppresses side reactions while also exhibiting relatively good lithium ion conductivity.

[0010] An example of an embodiment of a nonaqueous electrolyte secondary battery according to the present disclosure will be described in detail below. Hereinafter, a cylindrical battery in which a wound electrode assembly is housed in a cylindrical battery case will be exemplified. However, the electrode assembly is not limited to the wound type and may be a laminated type in which multiple positive electrodes and multiple negative electrodes are alternately stacked one by one with separators interposed therebetween. Furthermore, the battery case is not limited to a cylindrical shape and may be, for example, a prismatic or coin-shaped battery case, or may be a battery case made of a laminate sheet including a metal layer and a resin layer.

[0011] FIG. 1 is an axial cross-sectional view of a cylindrical secondary battery 10 according to an embodiment. The secondary battery 10 shown in FIG. 1 includes an electrode assembly 14 and a nonaqueous electrolyte housed in an outer casing 15. The electrode assembly 14 has a wound structure in which a positive electrode 11 and a negative electrode 12 are wound with a separator 13 interposed therebetween. Examples of nonaqueous solvents (organic solvents) for the nonaqueous electrolyte include carbonates, lactones, ethers, ketones, and esters, and two or more of these solvents can be mixed. When two or more solvents are mixed, a mixed solvent containing a cyclic carbonate and a chain carbonate is preferably used. For example, ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and the like can be used as the cyclic carbonate, and dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and the like can be used as the chain carbonate. Examples of electrolyte salts that can be used for the non-aqueous electrolyte include LiPF, LiBF, LiCF, SO, and mixtures thereof. The amount of electrolyte salt dissolved in the non-aqueous solvent can be, for example, 0.5 to 2.0 mol / L. For ease of explanation, the following description will refer to the sealing body 16 side as "top" and the bottom side of the exterior body 15 as "bottom."

[0012] The open end of the exterior body 15 is sealed with the sealing body 16, thereby sealing the interior of the secondary battery 10. Insulating plates 17 and 18 are provided above and below the electrode body 14. The positive electrode lead 19 extends upward through a through hole in the insulating plate 17 and is welded to the underside of a filter 22, which is the bottom plate of the sealing body 16. In the secondary battery 10, a cap 26, which is the top plate of the sealing body 16 and is electrically connected to the filter 22, serves as the positive electrode terminal. On the other hand, the negative electrode lead 20 extends through a through hole in the insulating plate 18 toward the bottom of the exterior body 15 and is welded to the inner bottom surface of the exterior body 15. In the secondary battery 10, the exterior body 15 serves as the negative electrode terminal. Note that if the negative electrode lead 20 is installed at the terminal end, the negative electrode lead 20 passes outside the insulating plate 18, extends toward the bottom of the exterior body 15, and is welded to the inner bottom surface of the exterior body 15.

[0013] Exterior body 15 is, for example, a cylindrical metal exterior can with a bottom. A gasket 27 is provided between exterior body 15 and sealing body 16, ensuring the airtightness of the interior of secondary battery 10. Exterior body 15 has a grooved portion 21 that supports sealing body 16, formed, for example, by pressing the side surface from the outside. Grooved portion 21 is preferably formed in an annular shape along the circumferential direction of exterior body 15, and supports sealing body 16 on its upper surface via gasket 27.

[0014] The sealing body 16 includes a filter 22, a lower valve body 23, an insulating member 24, an upper valve body 25, and a cap 26, which are stacked in this order from the electrode body 14 side. Each component of the sealing body 16 has, for example, a disk or ring shape, and all components except for the insulating member 24 are electrically connected to each other. The lower valve body 23 and the upper valve body 25 are connected to each other at their respective centers, with the insulating member 24 interposed between their respective peripheral edges. If the internal pressure of the battery increases due to abnormal heat generation, for example, the lower valve body 23 may break, causing the upper valve body 25 to bulge toward the cap 26 and separate from the lower valve body 25, thereby cutting off the electrical connection between them. If the internal pressure continues to increase, the upper valve body 25 may break, and gas may be released from the opening 26a of the cap 26.

[0015] Hereinafter, the positive electrode 11, negative electrode 12, and separator 13 that constitute the secondary battery 10 will be described in detail, particularly the positive electrode active material contained in the negative electrode mixture layer that constitutes the positive electrode 11.

[0016] [Positive electrode] The positive electrode 11 has, for example, a positive electrode core such as a metal foil and a positive electrode composite layer formed on the positive electrode core. The positive electrode core can be a foil of a metal such as aluminum that is stable within the potential range of the positive electrode, or a film with such a metal disposed on the surface layer. The positive electrode composite layer contains, for example, a positive electrode active material, a binder, a conductive material, etc. The positive electrode can be produced, for example, by applying a positive electrode composite slurry containing the positive electrode active material, the binder, the conductive material, etc. to the positive electrode core, drying the slurry to form a positive electrode composite layer, and then rolling the positive electrode composite layer.

[0017] Examples of conductive materials contained in the positive electrode mixture layer include carbon particles such as carbon black (CB), acetylene black (AB), ketjen black, graphite, etc. These may be used alone or in combination of two or more.

[0018] Examples of binders contained in the positive electrode mixture layer include fluorine-based resins such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVdF), polyacrylonitrile (PAN), polyimide-based resins, acrylic-based resins, polyolefin-based resins, etc. These may be used alone or in combination of two or more.

[0019] The positive electrode active material contains a lithium transition metal composite oxide capable of absorbing and desorbing Li. The lithium transition metal composite oxide may have a spinel structure. Whether the lithium transition metal composite oxide has a spinel structure can be confirmed by X-ray diffraction (XRD).

[0020] The lithium transition metal composite oxide is, for example, a secondary particle formed by agglomeration of a plurality of primary particles. The particle size of the primary particles constituting the secondary particle is, for example, 0.05 μm to 1 μm. The particle size of the primary particle is measured as the diameter of the circumscribed circle in a particle image observed with a scanning electron microscope (SEM).

[0021] The volume-based median diameter (D50) of the secondary particles of the lithium transition metal composite oxide is, for example, 3 μm to 30 μm, preferably 5 μm to 25 μm, and particularly preferably 7 μm to 15 μm. D50 refers to the particle size at which the cumulative frequency of the smallest particle size in the volume-based particle size distribution is 50%, and is also called the median diameter. The particle size distribution of the composite oxide (Z) can be measured using a laser diffraction particle size distribution analyzer (e.g., MT3000II, manufactured by Microtrack Bell Corporation) using water as the dispersion medium.

[0022] Lithium transition metal composite oxides have the general formula Li 1+α Ni 0.5-x Mn 1.5-y M x+yO a F b (wherein 0≦α≦0.2, 0≦x<0.2, 0≦y<0.5, 0≦b≦0.2, 3.8≦a+b≦4.2, and M is at least one element selected from Ti, Fe, Al, Ge, Si, Nb, Ta, Zr, W, Mo, Sc, Y, and Er.) The mole fraction of each element constituting the lithium transition metal composite oxide can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy for elements other than F, and by ion chromatography (IC) measurement for F.

[0023] In the formula (1 + α) that represents the proportion of Li in the lithium transition metal composite oxide, α satisfies 0≦α≦0.2, and preferably 0≦α≦1.05. When α is less than 0, the battery capacity may be reduced compared to when α satisfies the above range. When α exceeds 0.2, the charge-discharge cycle characteristics may be reduced compared to when α satisfies the above range.

[0024] In 0.5-x, which indicates the ratio of Ni to the total number of moles of metal elements excluding Li in the lithium transition metal composite oxide, x satisfies 0≦x<0.2, preferably 0≦x≦0.15, and more preferably 0≦x≦0.1.

[0025] In 1.5-y, which indicates the ratio of Mn to the total number of moles of metal elements excluding Li in the lithium transition metal composite oxide, y satisfies 0≦y<0.5, preferably 0≦y≦0.3, and more preferably 0≦y≦0.1.

[0026] M (where M is at least one element selected from Ti, Fe, Al, Ge, Si, Nb, Ta, Zr, W, Mo, Sc, Y, and Er) relative to the total number of moles of metal elements excluding Li in the lithium transition metal composite oxide is an optional component, and x+y, which indicates the ratio thereof, satisfies x+y≧0.

[0027] The ratio b of F in the lithium transition metal composite oxide satisfies 0≦b≦0.2, and preferably 0≦b≦0.1. The inclusion of F in the lithium transition metal composite oxide improves the stability of the crystal structure of the lithium transition metal composite oxide. The stabilization of the crystal structure of the lithium transition metal composite oxide improves the durability of the secondary battery, for example.

[0028] The positive electrode active material contains SrMnO3 inside or outside secondary particles of a lithium transition metal composite oxide. SrMnO3 suppresses side reactions while having relatively good lithium ion conductivity, so by being present inside or outside the secondary particles of the lithium transition metal composite oxide, the durability and battery capacity of the secondary battery can be improved.

[0029] The molar fraction of Sr contained in SrMnO3 relative to the total number of moles of metal elements excluding Li contained in the lithium transition metal composite oxide is 0.1% to 5%, preferably 0.2% to 5%, and more preferably 2% to 5%.

[0030] Hereinafter, for convenience of explanation, the positive electrode active material containing the lithium transition metal composite oxide and SrMnO3 contained inside or outside the secondary particles of the lithium transition metal composite oxide will be referred to as "composite oxide (Y)." In the present disclosure, the positive electrode active material contained in the secondary battery may contain the composite oxide (Y) as a main component and may be substantially composed of the composite oxide (Y) alone. Note that the positive electrode active material may contain a composite oxide other than the composite oxide (Y) or other compounds within a range that does not impair the object of the present disclosure.

[0031] The presence of SrMnO3 in the composite oxide (Y) can be confirmed by X-ray diffraction (XRD), and the content of SrMnO3 in the composite oxide (Y) can also be measured by XRD.

[0032] The composite oxide (Y) can be synthesized, for example, by adding a Li source and an Sr source to a composite compound (X) that does not contain Li, mixing the mixture, and firing the mixture at 200°C to 1050°C. Examples of the composite compound (X) include composite oxides, hydroxides, carbonates, etc. that contain Ni, Mn, etc. Examples of the Li source include LiOH, etc. Examples of the Sr source include Sr(OH)2, SrCO3, Sr(NO3)2, etc. The Sr source may be either a powdery solid or an aqueous solution in which the Sr source is dissolved. From the viewpoint of dispersing Sr inside or outside the secondary particles of the lithium transition metal composite oxide, the method of adding an aqueous solution is preferred. When adding an aqueous solution, the Sr source is preferably Sr(NO3)2, which has high solubility in water, from the viewpoint of facilitating the preparation of the aqueous solution.

[0033] [Negative electrode] The negative electrode 12 has, for example, a negative electrode core such as a metal foil and a negative electrode composite layer provided on the surface of the negative electrode core. The negative electrode core can be a foil of a metal such as copper that is stable within the potential range of the negative electrode, or a film with such a metal disposed on the surface layer. The negative electrode composite layer contains, for example, a negative electrode active material and a binder. The negative electrode can be produced, for example, by applying a negative electrode composite slurry containing the negative electrode active material, the binder, etc. to the negative electrode core, drying it to form a negative electrode composite layer, and then rolling this negative electrode composite layer.

[0034] The negative electrode mixture layer contains, as the negative electrode active material, for example, a carbon-based active material that reversibly absorbs and releases lithium ions. Suitable carbon-based active materials include natural graphite such as flake graphite, lump graphite, and amorphous graphite, and artificial graphite such as lump artificial graphite (MAG) and graphitized mesophase carbon microbeads (MCMB). The negative electrode active material may be a Si-based active material composed of at least one of Si and a Si-containing compound, or a combination of a carbon-based active material and a Si-based active material.

[0035] The binder contained in the negative electrode mixture layer can be, as in the case of the positive electrode, fluororesin, PAN, polyimide, acrylic resin, polyolefin, etc., but styrene-butadiene rubber (SBR) is preferred. The negative electrode mixture layer also preferably contains CMC or a salt thereof, polyacrylic acid (PAA) or a salt thereof, polyvinyl alcohol (PVA), etc. Among these, it is preferable to use SBR in combination with CMC or a salt thereof, or PAA or a salt thereof.

[0036] [Separator] The separator is made of a porous sheet having ion permeability and insulating properties. Specific examples of the porous sheet include a microporous thin film, a woven fabric, and a nonwoven fabric. Suitable materials for the separator include polyolefins such as polyethylene and polypropylene, and cellulose. The separator may have either a single-layer structure or a laminated structure. A heat-resistant layer or the like may be formed on the surface of the separator.

[0037] <Example> The present disclosure will be further described below with reference to examples, but the present disclosure is not limited to these examples.

[0038] Example 1 [Synthesis of positive electrode active material] Obtained by coprecipitation, the composition is Ni 0.5 Mn 1.5 Nickel-manganese composite hydroxide (OH)4 was calcined at 500°C to obtain nickel-manganese composite oxide (X).

[0039] Next, an aqueous solution of nickel-manganese composite oxide (X), LiOH, and Sr(NO3)2 was mixed so that the molar ratio of the total amount of Ni and Mn to Li and Sr was 1:0.5:0.002. This mixture was calcined at 900°C for 10 hours and then pulverized to obtain lithium composite oxide (Y). XRD confirmed that the lithium composite oxide (Y) contained SrMnO3. The molar fraction of Sr contained in SrMnO3 relative to the total number of moles of metal elements excluding Li contained in the lithium transition metal composite oxide was 0.16%. Since the amount of Sr(NO3)2 used as the raw material was 0.2%, the remaining Sr is thought to have been converted to SrO, and the molar fraction of SrO can be calculated to be 0.04%.

[0040] [Preparation of positive electrode] The positive electrode active material, acetylene black, and polyvinylidene fluoride (PVdF) were mixed in a solids mass ratio of 96.3:2.5:1.2, and an appropriate amount of N-methyl-2-pyrrolidone (NMP) was added. The mixture was then kneaded to prepare a positive electrode composite slurry. The positive electrode composite slurry was applied to both sides of a positive electrode core made of aluminum foil, and the coating was dried. The coating was then rolled using a roller and cut to a predetermined electrode size to obtain a positive electrode with a positive electrode composite layer formed on both sides of the positive electrode core. An exposed portion was provided on a portion of the positive electrode, exposing the surface of the positive electrode core.

[0041] [Preparation of negative electrode] Natural graphite was used as the negative electrode active material. The negative electrode active material, carboxymethyl cellulose sodium (CMC-Na), and styrene-butadiene rubber (SBR) were mixed in an aqueous solution at a solids mass ratio of 100:1:1 to prepare a negative electrode composite slurry. The negative electrode composite slurry was applied to both sides of a negative electrode core made of copper foil, and the coating was dried. The coating was then rolled using a roller and cut to a predetermined electrode size to obtain a negative electrode with a negative electrode composite layer formed on both sides of the negative electrode core. An exposed portion was provided in part of the negative electrode, exposing the surface of the negative electrode core.

[0042] [Preparation of non-aqueous electrolyte] A non-aqueous solvent was prepared by mixing fluoroethylene carbonate (FEC), ethylene carbonate (EC), and ethyl methyl carbonate (EMC) in a volume ratio of 1:1:6. LiPF6 was dissolved in the non-aqueous solvent at a concentration of 1.0 mol / L to prepare a non-aqueous electrolyte.

[0043] [Battery construction] An aluminum lead was attached to the exposed portion of the positive electrode, and a nickel lead was attached to the exposed portion of the negative electrode, and the positive and negative electrodes were spirally wound with a polyolefin separator interposed therebetween, followed by radial press forming to produce a flat wound electrode assembly. This electrode assembly was housed in an exterior body made of an aluminum laminate sheet, and the nonaqueous electrolyte was poured into it. The opening of the exterior body was then sealed to obtain a nonaqueous electrolyte secondary battery with a design capacity of 650 mAh.

[0044] [Capacity retention rate evaluation] First, the battery fabricated above was charged at a constant current of 0.2 C in a temperature environment of 25°C until the battery voltage reached 4.9 V, and then charged at a constant voltage of 0.02 C at 4.9 V. Subsequently, it was discharged at a constant current of 0.2 C until the battery voltage reached 3.0 V. This charge-discharge cycle was repeated 7 times, and the battery was used as an initial battery.

[0045] The initial battery was subjected to the following cycle test. The discharge capacity at the first cycle and the discharge capacity at the 19th cycle of the cycle test were determined, and the capacity retention rate was calculated using the following formula.

[0046] Capacity retention rate (%) = (19th cycle discharge capacity ÷ 1st cycle discharge capacity) × 100 <Cycle test> The test cell was charged at a constant current of 0.2 C in a temperature environment of 25°C until the battery voltage reached 4.9 V, and then charged at a constant voltage of 0.02 C at 4.9 V. It was then discharged at a constant current of 0.2 C until the battery voltage reached 3.0 V. This charge / discharge cycle was repeated 19 times.

[0047] <Example 2> A battery was fabricated and evaluated in the same manner as in Example 1, except that an aqueous solution of nickel-manganese composite oxide (X), LiOH, and Sr(NO3)2 was mixed so that the molar ratio of the total amount of Ni and Mn to Li and Sr was 1:0.5:0.02. XRD confirmed that the lithium composite oxide (Y) contained SrMnO3. The molar fraction of Sr contained in SrMnO3 relative to the total number of moles of metal elements excluding Li contained in the lithium transition metal composite oxide was 0.96%.

[0048] <Comparative Example 1> A battery was fabricated and evaluated in the same manner as in Example 1, except that no Sr source was added and nickel manganese composite oxide (X) and LiOH were mixed so that the molar ratio of the total amount of Ni and Mn to Li was 1:0.5. XRD did not confirm any peaks derived from SrMnO3 in the lithium composite oxide (Y).

[0049] <Comparative Example 2> A lithium composite oxide (Z) was synthesized by adding an aqueous solution of Sr(NO3)2 to the lithium composite oxide (Y) obtained in Comparative Example 1 so that the molar ratio of the total amount of Ni and Mn to Sr was 1:0.002, and the mixture was fired at 900°C for 10 hours and then pulverized, and a battery was fabricated and evaluated in the same manner as in Comparative Example 1, except that this was used as the positive electrode active material. XRD did not confirm any peaks derived from SrMnO3 in the lithium composite oxide (Y).

[0050] <Comparative Example 3> A battery was fabricated and evaluated in the same manner as in Comparative Example 2, except that an aqueous solution of Sr(NO3)2 was added to the lithium composite oxide (Y) obtained in Comparative Example 1 so that the molar ratio of the total amount of Ni and Mn to Sr was 1:0.02. XRD did not confirm any peaks derived from SrMnO3 in the lithium composite oxide (Y).

[0051] The results of the discharge capacity and capacity retention rate at the 19th cycle for the batteries of the examples and comparative examples are summarized in Table 1. Table 1 also shows whether or not SrMnO3 was detected, the molar fraction of SrMnO3, and the molar fraction of SrO calculated from the difference between the amount added and the molar fraction of SrMnO3.

[0052] [Table 1]

[0053] All of the batteries of the Examples had higher discharge capacities and capacity retention rates than the batteries of the Comparative Examples. The battery of Comparative Example 3 had a high capacity retention rate but a low discharge capacity. Furthermore, X-ray diffraction patterns of Example 2 and Comparative Example 3 are shown in Figure 2 as an example showing peaks derived from SrMnO3. [Explanation of symbols]

[0054] 10 Secondary battery 11 Positive electrode 12 Negative electrode 12a End of winding 13 Separator 14 Electrode body 15 Exterior body 16 Sealing body 17,18 Insulating plate 19 Positive lead 20 Negative lead 21 Grooved part 22 filters 23 Lower valve body 24 Insulating material 25 Upper valve body 26 Cap 26a opening 27 Gasket

Claims

1. A positive electrode active material containing a lithium transition metal composite oxide capable of absorbing and releasing Li, The secondary particles of the lithium transition metal composite oxide are formed inside or outside of SrMnO ３ Including, SrMnO relative to the total number of moles of metal elements excluding Li contained in the lithium transition metal composite oxide ３ The molar fraction of Sr contained in is 2% to 5%; The lithium transition metal composite oxide is a positive electrode active material for a non-aqueous electrolyte secondary battery, and is represented by the general formula Li1+αNi0.5-xMn1.5-yMx+yOaFb (wherein 0≦α≦0.2, 0≦x<0.2, 0≦y<0.5, 0≦b≦0.2, 3.8≦a+b≦4.2, and M is at least one element selected from Ti, Fe, Al, Ge, Si, Nb, Ta, Zr, W, Mo, Sc, Y, and Er).

2. a positive electrode comprising the positive electrode active material for a non-aqueous electrolyte secondary battery according to claim 1; a negative electrode; and an electrolyte.

3. SrMnO inside or outside the secondary particles ３ a method for producing a positive electrode active material for a non-aqueous electrolyte secondary battery, which contains a lithium transition metal composite oxide capable of absorbing and desorbing Li, the lithium transition metal composite oxide being represented by the general formula Li1+αNi0.5-xMn1.5-yMx+yOaFb (wherein 0≦α≦0.2, 0≦x<0.2, 0≦y<0.5, 0≦b≦0.2, 3.8≦a+b≦4.2, and M is at least one element selected from Ti, Fe, Al, Ge, Si, Nb, Ta, Zr, W, Mo, Sc, Y, and Er), The lithium transition metal composite oxide is obtained by mixing a composite compound (X) that does not contain Li but contains Mn, a Li source, and an aqueous solution in which a Sr source is dissolved, and then baking the mixture at 200°C to 1050°C.

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