KR101938962B1 - Positive active material for potassium secondary batteries, potassium secondary batteries comprising the positive active material - Google Patents

Abstract

The present invention relates to a cathode active material for a potassium secondary battery, and a cathode active material according to the present invention is a crystalline material containing K, a transition metal, P and O, Wherein the Bragg angle (2?) Of the X-ray diffraction pattern is in the range of 14.7 to 15.7, 22.1 to 23.1, 25.5 to 26.5, and 29.7 to 30.8 when the relative intensity of the diffraction peak is 100% And an image showing a diffraction peak having a relative intensity of 5% or more as a columnar phase.

Description

FIELD OF THE INVENTION The present invention relates to a positive electrode active material for a potassium secondary battery, and a potassium secondary battery including the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

The present invention relates to a cathode active material for a potassium secondary battery and a potassium secondary battery comprising the same.

It is required to use the energy produced due to depletion of fossil fuels such as petroleum and coal and environmental pollution due to use in fossil fuels, and the energy produced by environmentally friendly methods such as solar energy, wind energy, Therefore, there is a growing interest in large-capacity secondary batteries that store the produced energy to meet the demand.

Lithium secondary batteries, which are the most popular secondary batteries so far, are capable of charging and discharging electric energy for a long period of time at a high density, and their use is rapidly increased for power sources for portable electronic devices and electric vehicles In addition, it is widely used for energy storage system (ESS) to store electric power generated by a power plant or to efficiently manage electric energy produced by solar energy or wind energy.

Lithium used in lithium secondary batteries has a problem that it is difficult to cope with a demand for a battery and an energy storage device which are not only high in price because limited resources are localized in a specific region, and are increasing.

In order to solve these problems, there is a growing interest in non-lithium batteries that do not use lithium as a main raw material. Non-lithium batteries use alkali metals, alkaline earth metals, Group 3A metals, transition metals and the like.

The alkali metal ion of Na ^+, K ⁺ is the secondary battery based on the endowment is much the price is significantly lower than that for Li-ion battery, in particular can be suitably used in a battery for ESS.

As cathode active materials for sodium ion batteries, layered metal oxides such as O3, P2 and P3, prussian blue having an open skeletal structure, phosphates, fluorescent phosphates, pyrophosphates and sulfides have been developed , Yet there are few substances that satisfy sufficient levels of capacity, longevity, and so on.

Potassium has a similar potential to lithium and has an excellent mobility of potassium ions, so the potential for secondary batteries is considerable, but has received little attention so far. Accordingly, studies on Prussian blue-like materials (KFe ^III Fe ^II (CN) ₆ ) disclosed in the following Patent Literature have been actively conducted as cathode active materials for potassium secondary batteries, and K _x TiS ₂ , K _x CoO ₂ , K _x MnO ₂ can also be used as a cathode active material. However, compared to a lithium secondary battery or a sodium secondary battery, a cathode active material for a potassium secondary battery has been rarely studied.

U.S. Patent No. 9385370

The object of the present invention is to provide a substance which can be used as a cathode active material for a potassium secondary battery and a potassium secondary battery comprising the substance.

In one embodiment of the present invention, when a crystalline material containing K, a transition metal, P and O is used and the relative intensity of the diffraction peak having the highest intensity in the powder X-ray diffraction pattern of the material is taken as 100% An image showing a diffraction peak having a relative intensity of 5% or more in a range of Bragg angles (2?) Of 14.7 to 15.7, A cathode active material for a potassium secondary battery.

In one embodiment of the invention, the material may have a composition of formula (I).

[Chemical Formula 1]

The present invention of the formula (K M1 _{a 1- a) (1- b} M2 _b M3) P _c O _d M2 and M3 are at least one element selected from the group consisting of Li, Na, Rb, Mg and Ca and M2 and M3 are at least one element selected from the group consisting of V, Ti, Fe, Cr, Mo, Mn, Co, Ni, Al, , Wherein the relative intensity of the highest intensity diffraction peak in the powder X-ray diffraction pattern is 100%, the Bragg angle of the X-ray diffraction pattern (2 &thetas; B, c ") showing a diffraction peak having a relative intensity of 5% or more in the range of 14.7 to 15.7, 22.1 to 23.1, 25.5 to 26.5 and 29.7 to 30.8, And d is 0? A? 0.2, 0? B? 0.7, 1.8? C? 2.2, and 6.8? D? 7.2.

According to one embodiment of the present invention, it is expected that reversible insertion / desorption of potassium ions is easy and structural stability is excellent, so that charge and discharge cycle characteristics are excellent, and it can be suitably used particularly for ESS.

The cathode active material for a potassium secondary battery according to an embodiment of the present invention may be a non-aqueous electrolyte.

According to another embodiment of the present invention, there is provided a potassium secondary battery comprising the cathode active material for the potassium secondary battery.

FIG. 1 is a graph showing the results of a Bragg angle (2?) Of a ray diffraction pattern of a cathode active material synthesized according to Example 1 of the present invention of 14.7 to 15.7, 22.1 to 23.1, 25.5 to 26.5, 29.7 to 30.8 Quot ;.
Fig. 2 shows the ray diffraction patterns of the cathode active material synthesized according to Examples 1 to 18 of the present invention.
Fig. 3 shows the ray diffraction patterns of the cathode active material synthesized according to Examples 19 to 36 of the present invention.
4 shows a line diffraction pattern of a cathode active material synthesized according to Example 37 of the present invention.
FIG. 5 shows the results of the first charge / discharge of the cathode active material synthesized according to Examples 1 to 6 of the present invention.
FIG. 6 shows the results of the first charge / discharge of the cathode active material synthesized according to Examples 7 to 12 of the present invention.
FIG. 7 shows the first charge / discharge results for the cathode active material synthesized according to Examples 12 to 18 of the present invention.
FIG. 8 shows the first charge / discharge results for the cathode active material synthesized according to Examples 19 to 24 of the present invention. FIG.
FIG. 9 shows the first charge / discharge results of the cathode active material synthesized according to Examples 25 to 30 of the present invention.
FIG. 10 shows the results of the first charge and discharge for the cathode active material synthesized according to Examples 31 to 36 of the present invention.
FIG. 11 shows the results of the first charge-discharge for the cathode active material synthesized according to Example 37 of the present invention.
FIG. 12 shows the 10th charge / discharge results of the cathode active material synthesized according to Examples 1 to 6 of the present invention.
FIG. 13 shows the 10th charge / discharge results for the cathode active material synthesized according to Examples 7 to 12 of the present invention.
FIG. 14 shows the 10th charge / discharge results of the cathode active material synthesized according to Examples 12 to 18 of the present invention.
FIG. 15 shows the 10th charge / discharge results for the cathode active material synthesized according to Examples 19 to 24 of the present invention.
FIG. 16 shows the 10th charge and discharge results for the cathode active material synthesized according to Examples 25 to 30 of the present invention.
FIG. 17 shows the 10th charge and discharge results for the cathode active material synthesized according to Examples 31 to 36 of the present invention. FIG.
18 shows the tenth charge / discharge result for the cathode active material synthesized according to Example 37 of the present invention.

Hereinafter, a potassium secondary battery having a cathode active material and an anode including the cathode active material according to exemplary embodiments will be described in more detail. However, the following embodiments are presented by way of example, and the present invention is not limited thereto, but the present invention is defined by the scope of the following claims.

The positive electrode active material for a potassium secondary battery according to the present invention comprises K, a transition metal, P and O, wherein, when the relative intensity of the diffraction peak having the highest intensity in the powder X-ray diffraction pattern is taken as 100% Wherein the phase exhibiting diffraction peaks at relative Bragg angles (2?) Of 14.7 to 15.7, 22.1 to 23.1, 25.5 to 26.5 and 29.7 to 30.8, Lt; / RTI >

When the X-ray diffraction pattern is used, the cathode active material has a tunnel-like crystal structure, and potassium ions having a relatively larger ion radius than lithium or sodium are easily inserted And can be desorbed, so that the structural stability is improved, the charge / discharge cycle characteristic is excellent, and a battery using a nonaqueous electrolyte can be constituted.

The positive electrode active material for a potassium secondary battery may further include at least one selected from Li, Na, Rb, Al, La, Gd and Lu.

Further, the cathode active material may be a compound represented by the following formula (1).

[Chemical Formula 1]

(K _1-a M _{1 a} ) (M 2 _{1 -b} M _{3 b} ) P _c O _d

Wherein M < 1 > is at least one element selected from among alkali metal elements and alkaline earth metals except K, and < EMI ID = And M2 and M3 are at least one element selected from transition metals.

For example, the cathode active material may be a compound represented by the following formula (2).

(2)

(K _1-a M _{1 a} ) (M 2 _{1 -b} M _{3 b} ) P _c O _d

Wherein M < 1 > is at least one element selected from among alkali metal elements and alkaline earth metals except K, and < EMI ID = M2 and M3 are at least one element selected from V, Ti, Fe, Cr, Mo, Mn, Co, Ni, Al, La, Gd and Lu.

For example, the cathode active material may be a compound represented by the following formula (3).

(3)

(K _1-a M _{1 a} ) (V _1-b M _{3 b} ) P _c O _d

Wherein M1 is at least one element selected from the group consisting of alkali metal elements and alkaline earth metal elements other than K, and 0 < = a < = 0.2, , M3 is at least one element selected from Ti, Fe, Cr, Mo, Mn, Co, Ni, Al, La, Gd and Lu.

For example, the cathode active material may specifically be KVP ₂ O ₇ , KTiP ₂ O ₇ , KCrP ₂ O ₇ , KFeP ₂ O _7, or KMoP ₂ O ₇ .

According to another embodiment of the present invention, there is provided a positive electrode comprising a positive electrode including the positive electrode active material of the above composition, a negative electrode disposed at a predetermined distance from the positive electrode, a separator disposed between the positive electrode and the negative electrode, The secondary battery may be a lithium secondary battery.

The positive electrode may include a current collector and a positive electrode active material layer formed on the current collector.

The current collector may be a metal current collector, for example, an aluminum foil may be used.

The positive electrode active material layer may be prepared by forming a mixture of a positive electrode active material powder having the above composition and a conductive material, a binder, and a solvent to form a laminate on the metal current collector, Lt; RTI ID = 0.0 > a < / RTI >

However, the present invention is not limited to the above-mentioned method, but may be a form other than the above-mentioned method.

As the conductive material, carbon black, graphite fine particles, or the like may be used, but not limited thereto, and any material that can be used as a conductive material in the related art can be used. For example, graphite such as natural graphite or artificial graphite; Carbon black such as carbon black, acetylene black, ketjen black, channel black, fines black, lamp black, and summer black; Conductive fibers such as carbon fiber and metal fiber; Metal powders such as aluminum and nickel powder; Conductive whiskers made of zinc oxide, potassium titanate and the like; Conductive metal oxides such as titanium oxide; And conductive materials such as polyphenylene derivatives can be used.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene and mixtures thereof, styrene butadiene rubber-based polymers, etc. May be used, but are not limited thereto and can be used as long as they can be used as bonding agents in the art.

As the solvent, N-methylpyrrolidone, acetone, water or the like may be used, but not limited thereto, and any solvent which can be used in the technical field can be used. The content of the cathode active material, the conductive agent, the binder, and the solvent may be adjusted according to the characteristics required for the potassium secondary battery, and one or more of them may not be used if necessary.

The negative electrode may include a current collector and a negative electrode active material layer formed on the current collector.

The negative electrode active material layer may be prepared by mixing the negative electrode active material powder, the conductive material, the binder and the solvent, and then coated directly on the metal current collector or dried. Alternatively, the negative electrode active material composition may be cast on a separate substrate, And then laminated on the current collector.

The negative electrode active material is not particularly limited as long as it is used in a potassium secondary battery and is capable of reversibly intercalating / deintercalating potassium ions, for example, potassium metal, potassium alloy, carbonaceous material and the like.

The material capable of reversibly intercalating and deintercalating potassium ions may be a carbon-based material as long as it is a carbon-based negative electrode active material generally used in a conventional lithium secondary battery. For example, crystalline carbon, amorphous carbon, or mixtures thereof. The crystalline carbon may be, for example, amorphous, plate-like, flake, spherical or fibrous natural graphite; Or artificial graphite, and the amorphous carbon may be, for example, soft carbon or hard carbon, mesophase pitch carbide, calcined coke, or the like.

The content of the negative electrode active material, the conductive material, the binder, and the solvent may be controlled or the content of the conductive material, the binder and the solvent may be controlled or some of the components may be omitted depending on the application and configuration of the potassium secondary battery.

It is preferable that the separator has a low resistance to the movement of ions contained in the electrolyte and a good wetting property of the electrolyte.

The separator may be a nonwoven fabric or a woven fabric selected from, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE) Polyethylene, polypropylene and the like, which are widely used in the art.

The electrolyte is preferably a non-aqueous electrolyte and may be composed of an organic material, and the organic material may include a potassium salt dissolved in an organic solvent.

The organic solvent may be any organic solvent that can be used in the art. Examples of the solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate , N, N-dimethylformamide, dimethylacetamide, dimethylsulfoxide, tetrahydrofuran, tetrahydrofuran, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, , Dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof.

The potassium salt may be used without limitation, as long as it can be used as a potassium salt in the art.

The electrolyte may be a solid electrolyte such as an organic solid electrolyte or an inorganic solid electrolyte. When a solid electrolyte is used, the solid electrolyte may also serve as a separator.

The positive electrode, the negative electrode, the separator, and the electrolyte are generally housed in a case, such as a lithium secondary battery, in the same manner as a battery manufacturing method, and finally made into a battery.

At this time, the anode, the cathode, and the separator are stacked and wound, or are folded into multiple layers, and then the electrolyte is injected into the case and sealed. Materials of various materials such as metal and plastic may be used as the material of the case, and the shape of the case may be various forms such as a cylindrical shape, a square shape, and a pouch shape.

The present invention will be described in more detail with reference to the following examples, but the present invention should not be construed as being limited to the following examples.

Manufacture of cathode active material for potassium secondary battery

Hereinafter, a method for producing the cathode active material of the potassium secondary battery according to the present invention will be described in detail.

Potassium secondary battery positive electrode active material for a prepared raw material is the main component, K, V, Ti, Fe, Cr, Mo, Mn, Co, Ni, P, potassium carbonate (K ₂ CO _3), vanadium oxide (V ₂ O ₅ ), titanium dioxide (TiO _2), iron oxide (Fe ₂ O _3), chromium oxide (Cr ₂ O _3), molybdenum oxide (Mo ₂ O _5), manganese oxide (Mn ₂ O _3), cobalt oxide (Co ₂ O ₃ ), nickel oxide (NiO) and ammonium phosphate ((NH ₄ ) HPO ₄ ) powders were used.

The raw materials were weighed to a predetermined composition and mixed so that the amount of the mixture per sample was 3 g. The mixing of the raw materials as described above was performed by hand for 30 minutes in the atmosphere.

The thus obtained mixture samples are carried out in a nitrogen gas atmosphere or an air atmosphere in which H ₂ gas is 0 to 25%, with nitrogen gas having a pressure of not less than atmospheric pressure but not higher than 20 atm as a main component. The firing temperature is preferably 700 ° C to 1100 ° C, and more preferably 800 ° C or more to obtain a cathode active material of high quality potassium secondary battery. The firing time may be in the range of 30 minutes to 100 hours, preferably 2 hours to 24 hours, considering the quality and productivity.

Hereinafter, the cathode active material of the present invention will be described in detail with reference to more specific examples.

[Example 1]

0.4888 g of K ₂ CO _3, 0.6432 g of V ₂ O _{5, and} 1.8680 g of (NH ₄ ) ₂ HPO ₄ were weighed out respectively as raw material powders of the cathode active material composition of the potassium secondary battery of Example 1, And 3 g of raw material powder mixture was obtained by mixing by hand. 3 g of the raw powder mixture thus mixed was charged into a crucible, and a sintering treatment was performed in which a mixed gas containing 15% of H ₂ gas as a main component was flowed into the furnace at a rate of 500 cc / minute and heated at 800 ° C for 24 hours Followed by pulverization to obtain a potassium secondary battery positive electrode active material composition.

In order to evaluate the performance of the prepared potassium secondary battery cathode active material, a potassium halide battery was prepared. The potassium antimatter was prepared by mixing a positive electrode active material powder made of KVP ₂ O ₇ synthesized as described above, carbon powder (Super P) as a conductive material and polyvinylidene fluoride (Pvdf) as a binder in a weight ratio of 75:15:15 , N-methyl pyrrolidone (NMP) as a solvent was added thereto, followed by mixing and stirring to prepare a positive electrode slurry. This slurry was applied to an aluminum foil as a current collector and dried at 120 DEG C for 8 hours or more using an oven to prepare a cathode. In addition, potassium foil was used as a cathode and a reference electrode.

A separator composed of a porous polyethylene membrane was disposed between the anode and the cathode thus prepared, and then an electrolytic solution (0.5M KPF6 / FEC: Ethyl methyl cabonate) was injected to form a coin cell ).

[Example 2]

A positive electrode was prepared in the same manner as in Example 1 except that the composition of the raw material powder was changed to 0.4952 g of K ₂ CO _3, 0.3258 g of V ₂ O _5, 0.2863 g of TiO _{2 and} 1.8927 g of (NH ₄ ) ₂ HPO ₄ , A coin cell was prepared.

[Example 3]

Except that the composition of the raw material powder was changed to 0.4952 g of K ₂ CO _3, 0.3259 g of V ₂ O _5, 0.2861 g of Fe ₂ O _{3 and} 1.8929 g of (NH ₄ ) ₂ HPO ₄ , And a coin cell was prepared.

[Example 4]

A positive electrode was prepared in the same manner as in Example 1 except that the composition of the raw material powder was 0.4528 g of K ₂ CO _3, 0.2979 g of V ₂ O _5, 0.5188 g of CrCl _{3, and} 1.7305 g of (NH ₄ ) ₂ HPO ₄ , A coin cell was prepared.

[Example 5]

A positive electrode was prepared in the same manner as in Example 1 except that the composition of the raw material powder was 0.4683 g of K ₂ CO _3, 0.3082 g of V ₂ O _5, 0.4335 g of MoO _{2 and} 1.7900 g of (NH ₄ ) ₂ HPO ₄ , A coin cell was prepared.

[Example 6]

The same procedure as in Example 1 was repeated except that the composition of the raw material powder was changed to 0.4958 g of K ₂ CO _3, 0.3262 g of V ₂ O _5, 0.2832 g of Mn ₂ O _{3, and} 1.8949 g of (NH ₄ ) ₂ HPO ₄ And a coin cell was prepared.

[Example 7]

The same procedure as in Example 1 was repeated except that the composition of the raw material powder was changed to 0.4950 g of K ₂ CO _3, 0.3257 g of V ₂ O _5, 0.2875 g of Co ₃ O _{4, and} 1.8918 g of (NH ₄ ) ₂ HPO ₄ And a coin cell was prepared.

[Example 8]

A positive electrode was prepared in the same manner as in Example 1 except that the composition of the raw material powder was 0.4983 g of K ₂ CO _3, 0.3279 g of V ₂ O _5, 0.2693 g of NiO, and 1.9045 g of (NH ₄ ) ₂ HPO ₄ , Coin cells were prepared.

[Example 9]

The composition of the raw material powder was the same as in Example 1 except that 0.4974 g of K ₂ CO _3, 0.2182 g of V ₂ O _5, 0.1917 g of TiO _2, 0.1916 g of Fe ₂ O _{3 and} 1.9011 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 10]

The composition of the raw material powder was the same as in Example 1 except that 0.4680 g of K ₂ CO _3, 0.2053 g of V ₂ O _5, 0.1804 g of TiO _2, 0.3575 g of CrCl _{3 and} 1.7888 g of (NH ₄ ) ₂ HPO ₄ were used , And a coin cell was produced.

[Example 11]

The composition of the raw material powder was the same as that of Example 1 except that 0.4790 g of K ₂ CO _3, 0.2101 g of V ₂ O _5, 0.1846 g of TiO _2, 0.2956 g of MnO _{2 and} 1.8307 g of (NH ₄ ) ₂ HPO ₄ , And a coin cell was produced.

[Example 12]

The composition of the raw material powder was the same as in Example 1 except that 0.4978 g of K ₂ CO _3, 0.2184 g of V ₂ O _5, 0.1918 g of TiO _2, 0.1895 g of Mn ₂ O _{3 and} 1.9025 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 13]

The composition of the raw material powder was the same as in Example 1 except that 0.4972 g of K ₂ CO _3, 0.2181 g of V ₂ O _5, 0.1916 g of TiO _2, 0.1925 g of Co ₃ O _{4 and} 1.9005 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 14]

The composition of the raw material powder was the same as in Example 1 except that the composition was changed to 0.4995 g of K ₂ CO _3, 0.2191 g of V ₂ O _5, 0.1925 g of TiO _2, 0.1799 g of NiO and 1.9090 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared, and a coin cell was produced.

[Example 15]

The composition of the raw material powder was the same as in Example 1 except that 0.4680 g of K ₂ CO _3, 0.2053 g of V ₂ O _5, 0.1803 g of Fe ₂ O _3, 0.3575 g of CrCl _{3 and} 1.7889 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 16]

The composition of the raw material powder was the same as in Example 1 except that 0.4790 g of K ₂ CO _3, 0.2101 g of V ₂ O _5, 0.1845 g of Fe ₂ O _3, 0.2956 g of MnO _{2 and} 1.8308 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 17]

Except that the composition of the raw material powder was changed to 0.4978 g of K ₂ CO _3, 0.2184 g of V ₂ O _5, 0.1917 g of Fe ₂ O _3, 0.1895 g of Mn ₂ O _{3 and} 1.9026 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 18]

Except that the composition of the raw material powder was changed to 0.4973 g of K ₂ CO _3, 0.2181 g of V ₂ O _5, 0.1915 g of Fe ₂ O _3, 0.1925 g of Co ₃ O _{4 and} 1.9006 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 19]

Except that the composition of the raw material powder was changed to 0.4995 g of K ₂ CO _3, 0.2191 g of V ₂ O _5, 0.1924 g of Fe ₂ O _3, 0.1800 g of NiO and 1.9091 g of (NH ₄ ) ₂ HPO _4. A positive electrode was prepared in the same manner to prepare a coin cell.

[Example 20]

The composition of the raw material powder was the same as in Example 1 except that 0.4517 g of K ₂ CO _3, 0.1981 g of V ₂ O _5, 0.3450 g of CrCl _3, 0.2788 g of MoO _{2 and} 1.7264 g of (NH ₄ ) ₂ HPO ₄ , And a coin cell was produced.

[Example 21]

Except that the composition of the raw material powder was changed to 0.4684 g of K ₂ CO _3, 0.2055 g of V ₂ O _5, 0.3578 g of CrCl _3, 0.1783 g of Mn ₂ O _{3 and} 1.7901 g of (NH ₄ ) ₂ HPO ₄ , To prepare a positive electrode, and a coin cell was produced.

[Example 22]

Except that the composition of the raw material powder was changed to 0.4679 g of K ₂ CO _3, 0.2052 g of V ₂ O _5, 0.3574 g of CrCl _3, 0.1812 g of Co ₃ O _{4 and} 1.7883 g of (NH ₄ ) ₂ HPO ₄ , To prepare a positive electrode, and a coin cell was produced.

[Example 23]

The composition of the raw material powder was the same as in Example 1 except that 0.4699 g of K ₂ CO _3, 0.2061 g of V ₂ O _5, 0.3589 g of CrCl _3, 0.1693 g of NiO and 1.7958 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared, and a coin cell was produced.

[Example 24]

The composition of the raw material powder was the same as in Example 1 except that 0.4793 g of K ₂ CO _3, 0.2103 g of V ₂ O _5, 0.2958 g of MoO _2, 0.1825 g of Mn ₂ O _{3 and} 1.8321 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 25]

The composition of the raw material powder was the same as in Example 1 except that 0.4789 g of K ₂ CO _3, 0.2101 g of V ₂ O _5, 0.2955 g of MoO _2, 0.1854 g of Co ₃ O _{4 and} 1.8302 g of (NH ₄ ) ₂ HPO ₄ were used. To prepare a positive electrode, and a coin cell was produced.

[Example 26]

The composition of the raw material powder was the same as in Example 1 except that the composition was changed to 0.4809 g of K ₂ CO _3, 0.2110 g of V ₂ O _5, 0.2968 g of MoO _2, 0.1733 g of NiO and 1.8381 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared, and a coin cell was produced.

[Example 27]

Except that the composition of the raw material powder was changed to 0.4976 g of K ₂ CO _3, 0.2183 g of V ₂ O _5, 0.1895 g of Mn ₂ O _3, 0.1927 g of Co ₃ O _{4 and} 1.9019 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 28]

Except that the composition of the raw material powder was changed to 0.4999 g of K ₂ CO _3, 0.2193 g of V ₂ O _5, 0.1903 g of Mn ₂ O _3, 0.1801 g of NiO and 1.9105 g of (NH ₄ ) ₂ HPO _4. A positive electrode was prepared in the same manner to prepare a coin cell.

[Example 29]

The composition of the raw material powder was the same as that of Example 1 except that the composition was changed to 0.4993 g of K ₂ CO _3, 0.2190 g of V ₂ O _5, 0.1933 g of Co ₃ O _4, 0.1799 g of NiO and 1.9084 g of (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner to prepare a coin cell.

[Example 30]

Except that the composition of the raw material powder was 0.4432 g of K ₂ CO _3, 0.6481 g of V ₂ O _5, 0.0263 g of Li ₂ CO _{3 and} 1.8823 g of (NH ₄ ) ₂ HPO ₄ , And a coin cell was prepared.

[Example 31]

The composition of the raw material powder was 0.4416 g of K ₂ CO _3, 0.6456 g of V ₂ O _5, 0.0376 g of Na ₂ CO ₃ , (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 32]

The composition of the raw material powder was 0.4351 g of K ₂ CO _3, 0.6362 g of V ₂ O _5, 0.0808 g of Rb ₂ O ₃ , (NH ₄ ) ₂ HPO ₄ A positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 33]

The composition of the raw material powder was 0.4934 g of K ₂ CO _3, 0.5844 g of V ₂ O _5, 0.0364 g of V ₂ O ₃ , (NH ₄ ) ₂ HPO ₄ The positive electrode was prepared in the same manner as in Example 1, and a coin cell was produced.

[Example 34]

A positive electrode was prepared in the same manner as in Example 1, except that the composition of the raw material powder was 0.4806 g of K ₂ CO _3, 0.5692 g of V ₂ O _5, 0.1133 g of Al ₂ O _{3, and} 1.8369 g of (NH ₄ ) ₂ HPO ₄ And a coin cell was prepared.

[Example 35]

A positive electrode was prepared in the same manner as in Example 1 except that 0.4786 g of K ₂ CO _3, 0.5668 g of V ₂ O _5, 0.1255 g of La ₂ O _{3 and} 1.8291 g of (NH ₄ ) ₂ HPO ₄ were used as raw material powders And a coin cell was prepared.

[Example 36]

The same procedure as in Example 1 was repeated except that the composition of the raw material powder was changed to 0.4766 g of K ₂ CO _3, 0.5645 g of V ₂ O _5, 0.1372 g of Gd ₂ O _{3, and} 1.8217 g of (NH ₄ ) ₂ HPO ₄ And a coin cell was prepared.

[Example 37]

The same as the composition of the raw material _{powder, K 2 CO 3 0.4345g, MoO} 2 0.9050g, (NH 4) in Example 1, except that the 2HPO ₄ 1.6605g to produce a positive electrode to prepare a coin cell.

XRD  analysis

Powder X-ray diffraction was performed to analyze the crystal structure of the cathode active material synthesized according to Examples 1 to 36, and the results are shown in FIGS. 1 to 3. FIG.

The X-ray diffraction analysis was performed using a diffractometer (model: D / MAX2500V / PC powder diffractometer,? = 1.5405?) Using a diffractometer (manufacturer: Rigaku Model: 2 > theta (2 &thetas;) was in the range of 10 to 80 DEG and 0.2 DEG per minute.

FIG. 1 shows XRD diffraction analysis results according to Example 1 of the present invention. The Bragg angle (2?) Of the X-ray diffraction pattern of the present invention is 14.7 ° to 15.7 °, 22.1 ° to 23.1 °, Deg.] To 26.5 [deg.], And 29.7 [deg.] To 30.8 [deg.].

2 to 4, in Examples 2 to 37 of the present invention, the Bragg angle (2?) Was 14.7 ° to 15.7 °, 22.1 ° to 23.1 °, 26.5 DEG and 29.7 DEG C to 30.8 DEG, respectively, and a diffraction peak having a relative intensity of 5% or more.

Evaluation of battery characteristics

The cell characteristics were evaluated with the thus prepared coin cell. The results are shown in FIGS. 5 to 18, and the numbers shown in FIGS. 4 to 18 indicate the order of the embodiments.

C-rate: 12 mA / g and cut-off: 2.0 V to 5.4 V were used for evaluating the characteristics of the battery.

Table 1 below shows the capacity of one cycle and ten cycles of the coin cell using the positive electrode prepared according to Examples 1 to 37. [

Example 1st cycle
Capacity (mAh / g) Tenth cycle
Capacity (mAh / g) charge Discharge charge Discharge One 117.5479 51.2634 65.8395 50.4012 2 78.4740 32.3062 45.0536 37.0842 3 89.4762 21.3546 46.4025 28.9539 4 56.5535 19.7825 32.3475 26.3301 5 56.5535 19.7825 32.3475 26.3301 6 69.7685 20.6473 32.2046 24.2256 7 174.3166 29.2949 50.7070 32.6744 8 270.5535 45.6793 49.9893 35.2444 9 253.4519 26.4667 36.9736 22.7879 10 68.4465 20.1204 31.3705 24.0434 11 187.1293 47.4293 49.6825 33.4117 12 36.7565 7.5408 10.6169 8.5019 13 36.7565 7.5408 10.6169 8.5019 14 286.0406 38.9994 37.7916 31.3147 15 182.0785 14.6451 24.1489 12.7888 16 242.3889 16.4903 79.7147 34.9506 17 117.0702 17.5034 26.0003 16.1618 18 242.2863 13.0562 35.6631 25.7841 19 329.7233 24.8532 34.0221 17.0443 20 631.0279 34.4352 56.9538 29.7499 21 21.9084 5.3025 12.8840 9.1126 22 754.5139 31.6436 37.7865 21.5670 23 257.4543 31.9925 41.2541 25.0494 24 711.8794 42.0565 80.6237 41.9073 25 1044.5680 53.9011 75.4187 41.9463 26 864.5000 55.2004 63.4230 35.6992 27 411.7310 18.1105 32.4082 16.6592 28 221.5977 34.1472 31.7954 20.1695 29 599.0928 24.7310 35.4204 19.8390 30 127.3513 66.2378 67.9234 64.9929 31 87.2183 47.7411 47.1652 44.3857 32 100.9744 53.3868 59.5881 55.4505 33 112.6637 59.8933 66.7075 58.2496 34 109.7573 41.9130 40.8234 37.3324 35 53.2168 16.8569 28.5120 23.7850 36 100.8606 44.7452 42.9312 39.5275 37 95.5956 35.9387 38.4399 34.1995

As shown in Table 1, it was confirmed that the positive electrode prepared according to Examples 1 to 37 of the present invention functions as a secondary battery.

In particular, in Example 1, Example 30, Example 31, Example 32, and Example 33, the discharge capacity at the first cycle was more than 50 mAh / g, the rate of decrease in the discharge capacity at the 10th cycle was low, It is expected to be excellent.

Claims (10)

K, a transition metal, a crystalline material comprising P and O,
The X-ray diffraction pattern had a Bragg angle (2?) Of 14.7 to 15.7, 22.1 to 23.1 (inclusive), and a relative intensity of the highest intensity diffraction peak , 25.5 ° to 26.5 °, and 29.7 ° to 30.8 °, wherein the phase exhibits a diffraction peak having a relative intensity of not less than 5%
Wherein the crystalline material has a composition represented by the following formula (1).
[Chemical Formula 1]
(K _1-a M _{1 a} ) (M 2 _{1 -b} M _{3 b} ) P _c O _d
(M1 is at least one alkali metal element other than K, M2 and M3 are at least one of transition metal elements, 0? A? 0.2, 0? B? 0.7, 1.8? C? 2.2 and 6.8? D? 7.2) delete The method according to claim 1,
Wherein the transition metal comprises at least one selected from the group consisting of V, Ti, Fe, Cr, Mo, Mn, Co, Ni, Al, La, Gd and Lu. The method according to claim 1,
Wherein the crystalline material comprises at least one selected from the group consisting of Li, Na, Rb, Al, La, Gd and Lu. The method according to claim 1,
Wherein the crystalline material comprises at least one selected from the group consisting of KVP ₂ O ₇ , KTiP ₂ O ₇ , KCrP ₂ O ₇ , KFeP ₂ O ₇ , and KMoP ₂ O ₇ . An anode, a cathode, and an electrolyte,
The positive electrode
K, the transition metal, P and O, and the relative intensity of the highest intensity diffraction peak in the powder X-ray diffraction pattern is 100%, the Bragg angle (2?) Of the X-ray diffraction pattern is 14.7 Wherein the phase exhibits a diffraction peak having a relative intensity of 5% or more in the range of 15.7 to 15.7, 22.1 to 23.1, 25.5 to 26.5, and 29.7 to 30.8,
Wherein the cathode active material has a composition represented by the following formula (1).
[Chemical Formula 1]
(K _1-a M _{1 a} ) (M 2 _{1 -b} M _{3 b} ) P _c O _d
(M1 is at least one alkali metal element other than K, M2 and M3 are at least one of transition metal elements, 0? A? 0.2, 0? B? 0.7, 1.8? C? 2.2 and 6.8? D? 7.2) delete The method according to claim 6,
Wherein the transition metal comprises at least one selected from V, Ti, Fe, Cr, Mo, Mn, Co, Ni, Al, La, Gd and Lu. The method according to claim 6,
Wherein the positive electrode active material comprises at least one selected from Li, Na, Rb, Al, La, Gd and Lu. The method according to claim 6,
Wherein the cathode active material comprises at least one selected from KVP ₂ O ₇ , KTiP ₂ O ₇ , KCrP ₂ O ₇ , KFeP ₂ O _7, and KMoP ₂ O ₇ .

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