KR20110085600A - Electrode-active anion-deficient lithium transition-metal phosphate, method for preparing the same, and electrochemical device using the same - Google Patents

Abstract

PURPOSE: A negative ion-deficient lithium transition metal phosphate compound, a producing method thereof, and an electrochemical device using thereof are provided to improve the ion conductivity, and the chemical stability. CONSTITUTION: A negative ion-deficient lithium transition metal phosphate compound is marked with chemical formula 1: Li_(1-x)M(PO_4)_(1-y). In the chemical formula 1, x is greater than 0 and smaller than 0.15. M is marked with chemical formula 2 M^A_aM^B_bM^T_tFe_(1-(a+b+t)). In the chemical formula 2, M^A is selected from the group consisting of group 2 elements.

Description

Anion-deficient lithium transition metal phosphate compound as an electrode active material, a method of manufacturing the same, and an electrochemical device using the same.

The present invention relates to an anion deficient lithium transition metal phosphate compound as an electrode active material, a method for producing the same, and an electrochemical device using the same.

Lithium secondary batteries have advantages of being lighter and higher in capacity than other secondary batteries such as nickel cadmium batteries (Ni // Cd) and nickel-hydrogen batteries (Ni // MH). Therefore, it serves as a power source for portable electric and electronic devices such as mobile phones, notebook computers, game consoles, and vacuum cleaners. Recently, the market is rapidly expanding to medium and large lithium secondary batteries for electric bicycles, electric scooters, service robots, electric vehicles, and power storage devices.

BACKGROUND ART Lithium secondary batteries have been generally manufactured using lithium cobaltate (LiCoO ₂ ) as a positive electrode active material, carbon material as a negative electrode active material, lithium hexafluorophosphate (LiPF ₆ ) as an electrolyte, and the like. However, lithium cobalt as a main positive electrode active material is not only unstable in the supply and demand of cobalt as a main component, but also has a high cost of cobalt, it is economically impossible to apply to the medium-large lithium secondary battery that requires a large amount. Therefore, spinel-structured lithium manganate (LiMn ₂ O ₄ ), etc., in which cobalt is replaced with another low-cost transition metal, has been commercially used, and a lithium transition, which may be represented by an olivine-type lithium iron phosphate (LiFePO ₄ ), may be used. Commercialization of metal phosphate compounds is underway.

The lithium transition metal phosphate compound having an olivine structure has high crystal structural stability and stability to chemical reactions, and has advantages of high capacity, long life, and low cost of a battery. Nevertheless, the commercialization is not easily proceeded due to the disadvantages of low electron conductivity, low ion conductivity and generation of impurities by side reactions. In particular, since the composition and crystal structure of the lithium transition metal phosphate compound are sensitively changed according to the preparation method, it is difficult to produce a desired composition and crystal structure, and it is difficult to produce fine particles having a homogeneous composition and crystal structure. It is difficult to prevent the production of compounds containing impurities that do not have an oxidation number). These problems of the prior art make the material and battery characteristics worse, resulting in a decrease in productivity, reliability, and economics, which has been a barrier to the commercialization of lithium transition metal phosphate compounds.

For example, in the case of lithium manganese phosphate (LiMnPO ₄ ), impurities such as Mn ₃ O ₄ , Mn ₂ O ₃ , MnO ₂ , MnP, Mn ₃ (PO ₄ ) ₄ are additionally generated, and are contained in the impurities. Most of the manganese is in a state where the oxidation number exceeds +2, because electronically, manganese has a strong tendency to be more than +3, and is easily oxidized during manufacturing and application. Lithium manganese phosphate compounds containing manganese having an oxidation number of +3 or more do not have a complete olivine structure and are compounds containing impurities. Since most impurities do not have electrochemical activity, lithium manganese phosphate containing manganese having an oxidation number of +3 or more exhibits poor characteristics as a battery material than lithium manganese phosphate composed only of manganese having an oxidation number of +2. Therefore, efforts have been made to prevent the generation of manganese having an oxidation number of more than +3.

The present invention provides an anion deficient lithium transition metal phosphate compound to overcome the problems of the prior art. Korean Patent Application No. 2009-0005540 discloses anion-deficient lithium iron phosphate Li _{1 - x} Fe (PO ₄ ) _1-y and its preparation method, but the compound according to the present invention is a Group 2 element, Group 13 element, Sc Is different from Korean Patent Application 2009-0005540 in that it must include at least one element selected from the group consisting of Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo. .

In addition, although there are known publications that disclose non-stoichiometric lithium transition metal phosphate compounds, the non-stoichiometric compounds disclosed in these publications are not anion-deficient but are cationic or cationic-deficient. It is different.

For example, European Patent Application EP-A-1,094,532 discloses a process for the production of compounds represented by Li _x M _y PO ₄ , where 0 <x ≦ 2, 0.8 ≦ y ≦ 1.2, and M is 3d. At least one metal having orbitals.

European Patent Application Publication No. EP-A-1,094,533 and Korean Patent Application Publication No. 2001-0025117 disclose a compound represented by the formula Li _x M _y PO ₄ , where 0 <x ≦ 2, 0.8 ≦ y ≦ 1.2, and M Contains a 3d transition state, and the grains of Li _x M _y PO ₄ are less than 10 micrometers.

US Patent Application Publication No. 2006 / 0263286A1 and Japanese Patent Application Publication No. 2006-131485 disclose a method for preparing Li _{1 + x} Fe _{1 + y} PO ₄ having an olivine structure, where -0.2≤x≤0.2 and -0.2 ≤ y ≤ 0.2.

US Patent Application Publication 2007 / 0207080A1 discloses a process for preparing Li _x M _y PO ₄ compounds having an olivine structure. The method produces a solution comprising the ions, Li ⁺ ions and PO ₄ ^{3 −} ions of the transition metal M, drying the solution to form starting material particles and having an olivine structure from the starting material particles. Forming Li _x M _y PO ₄ (0.8 ≦ _x ≦ 1.2, 0.8 ≦ _y ≦ 1.2) compound particles and coating the carbon layer on the Li _x M _y PO ₄ compound particles.

PCT Publication No. WO2003 / 077335 and Korean Patent Application Publication No. 2004-0094762 disclose compounds of the formula A _{a + x} M _b P _{1 - x} Si _x O ₄ as electrode materials, where A is Li, Na, K, and Selected from the group consisting of mixtures thereof, wherein 0 <a <1.0, 0 ≦ x ≦ 1, M comprises one or more metals which can be oxidized to a higher valence state, and also 0 <b <2, M, a, b and x are chosen to maintain the electrical neutrality of the compound.

However, the non-stoichiometric lithium transition metal phosphate compounds disclosed in the above-listed documents are all cationic or cation deficient compounds in which the molar ratio of anion PO ₄ is 1 and the molar ratio of M, which is a cation, is changed, such as Li _x M _y PO _4. In contrast to the anion-deficient non-stoichiometric lithium transition metal phosphate compound according to the present invention, it does not fundamentally solve the problems of the prior art.

In this regard, referring to the type of non-stoichiometric lithium transition metal phosphate compound, a ceramic material such as lithium transition metal phosphate compound is an ionic compound composed of cation (M ^{y +} ) and anion (X ^{y −} ), There are four possible point defects in nonstoichiometric ionic compounds.

The first is a cationic excess nonstoichiometric compound and the formula is represented by M _{1 + z} X. In this chemical formula, the composition ratio of anion (X ^{y −} ) is 1, which means that all the lattice points where anion (X ^{y −} ) should be present in the MX crystal structure are all disposed, and cation (M ^{y +} ) 'S composition ratio of 1 + z fills all the lattice points where cations (M ^{y +} ) should be, and the excess z moles of cations (M ^{y +} ) are arranged at interstitial sites rather than magnetic sites. Means. This point defect is called interstitial cation defect in crystallography. When there is 1 mole of negatively charged anion (X ^{y −} ) of -y and 1 + z mole of positively charged cation (M ^{y +} ) of ^{+ y} , charge neutralization cannot be achieved. Therefore, the cation is not a positive charge of + y but a cation (M ^{y ' +} ) of + y' [y '= y / (1 + z)], and the oxidation number of the cation decreases from + y to + y'.

The second is a cation deficient nonstoichiometric compound and the formula is represented by M _{1 - z} X. It is the composition ratio is 1, the anion (X ^{y -)} in MX crystal structure ^- anion (X ^y) in the formula means a state that is arranged both to all the grid points should be, and the composition ratio of the cation (M ^{y +)} 1 -z means that all the lattice points to which the cation (M ^{y +} ) should be filled are not filled and z molar vacancies are formed. This point defect is called cationic vacancy defect in crystallography. anion with a negative charge of -y ^(y X ^-) is 1 mol and + y positive charge when the cation (M ^{y +)} is less than 1 mol with 1-z of not be able to achieve charge neutrality. Therefore, the cation is not a positive charge of + y but a cation (M ^{y ' +} ) of + y' [y '= y / (1-z)], and the oxidation number of the cation increases from + y to + y'.

Third is an anion deficient nonstoichiometric compound and the formula is represented by MX _{1 -z} . In this chemical formula, the composition ratio of cation (M ^{y +} ) is 1, which means that all the lattice points where cation (M ^{y +} ) should be present in the MX crystal structure are all arranged, and the composition ratio of anion (X ^{y −} ) is 1 -z is an ^anion; means a state in which the public formed by z moles does not fill all of the all of the grid points to have the (X ^y). This defect is called anionic vacancy defect in crystallography. When there is 1 mole of positively charged cation (M ^{y +} ) and 1 negative moiety of negative ^y (X ^{y −} ) of -y, charge neutralization cannot be achieved. Common cations in ceramic materials are transition metal cations, and the oxidation number of the transition metal can be changed in a certain region, but the oxidation number of the anion is difficult to change. Therefore, the cation is not a positive charge of + y but a cation (M ^{y ' +} ) of + y' [y '= y (1-z)], and the oxidation number of the cation decreases from + y to + y'.

Fourth is an anion excess nonstoichiometric compound and the formula is represented by MX _{1 + z} . In this chemical formula, the composition ratio of cation (M ^{y +} ) is 1, which means that all the lattice points where cation (M ^{y +} ) should be present in the MX crystal structure are all arranged, and the composition ratio of anion (X ^{y −} ) is 1 + z means that all the lattice points where anions (X ^{y −} ) should be present are filled, and the excess z moles of anions (X ^{y −} ) are arranged at positions between lattice positions rather than magnetic sites. This point defect is called interstitial anion defect in crystallography. When there is 1 mole of positively charged cations (M ^{y +} ) and 1 negative moiety of negative ^y (X ^{y −} ), there is no charge neutrality. Therefore, the cation is not a positive charge of + y but a cation (M ^{y ' +} ) of + y' [y '= y (1 + z)], and the oxidation number of the cation increases from + y to + y'.

The problem to be solved by the present invention is to provide an anion-depleted lithium transition metal phosphate compound having high ion conductivity, low electrochemically inert impurities and improved electrode active material properties, and also a method for manufacturing the same and electrochemical using the same It is to provide an element.

The present invention is based on the unpredictable finding that electrochemical usefulness and performance can be surprisingly improved by controlling the amount and distribution of anionic vacancy of lithium transition metal phosphate compounds.

Anion-deficient non-stoichiometric lithium transition metal phosphate compound of the present invention is a compound represented by the following formula (1).

(Formula 1) Li _{1 - x} M (PO ₄ ) _1-y

In Formula 1, 0 ≦ x ≦ 0.15, 0 <y ≦ 0.05, M is represented by the following Formula 2,

(Formula 2) M ^A _a M ^B _b M ^T _t Fe _{1- (a + b + t)}

In Formula 2, M ^A is at least one element selected from the group consisting of Group 2 elements, M ^B is at least one element selected from the group consisting of Group 13 elements, M ^T is Sc, Ti, At least one element selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, where 0 ≦ a <1, 0 ≦ b <0.575, and 0 ≦ t≤1, 0≤ (a + b) <1, and 0 <(a + b + t) ≤1.

In another aspect, the present invention, generating a lithium transition metal phosphate precursor; Mixing the precursor with water under a reaction condition at a temperature of 200 to 700 ° C. and a pressure of 180 to 550 bar to synthesize an anion deficient lithium transition metal phosphate compound; It provides a method for producing an anion-depleted lithium transition metal phosphate compound comprising calcining the result, or after granulating and calcining.

Lithium transition metal phosphate compounds prepared by the prior art have generally been pointed out as a fundamental disadvantage that the low ionic conductivity, that is, the diffusion coefficient of lithium ions. In addition, since it is difficult to control the oxidation number of the transition metal during the manufacturing and application process, impurities that do not have an electrochemical activity easily occur. In the anion deficient lithium transition metal phosphate compound according to the present invention, these problems are fundamentally solved by anion vacancy in the crystal resulting from the anion depletion.

When anionic vacancy is formed, the diffusion path of lithium ions is expanded, and lithium ion diffusion is promoted during the desorption process by the repulsive force of lithium and transition metal cations arranged around the vacancy, thereby increasing the diffusion coefficient of lithium ions and improving ion conductivity. do. As the diffusion coefficient of lithium ions increases, the concentration gradient of lithium ions decreases from the surface portion of the crystal grains to the center portion, so that the resistance due to concentration polarization caused by the lithium ion diffusion rate difference decreases, thereby reducing the charge voltage and The spacing between the discharge voltages becomes relatively narrow. In addition, physical properties as an electrode material are improved, such as electrode resistance is reduced, output characteristics are improved, and discharge capacity is increased.

In addition, since the lithium transition metal phosphate compound of the present invention is in a state in which anion is deficient, the oxidation number of the metal cation contained in the compound is also lowered to satisfy the charge neutrality. Thus, the anion vacancy in the crystal suppresses oxidation of the transition metal to produce impurities having low electrochemical activity, thereby improving the characteristics of the electrode active material.

As a result, the anion-deficient non-stoichiometric lithium transition metal phosphate compound according to the present invention has higher ion conductivity and chemical stability than the conventional lithium transition metal phosphate compound, and ultimately improves the output, high capacity, and long-term performance of electrochemical devices including secondary batteries. The life characteristic can be aimed at. In addition, the production method according to the present invention is easier to produce anion-deficient non-stoichiometric lithium transition metal phosphate compound, compared to the prior art, and has high productivity, reliability and economy.

FIG. 1A is a scanning electron microscope (SEM) photograph taken at 1,000 times magnification showing particles of anion-deficient lithium manganese phosphate synthesized and granulated and calcined according to Example 1. FIG. FIG. 1B is a scanning electron microscope (SEM) photograph of a 50,000-fold magnification of a part of the granule of FIG. 1A, and shows nanometer-sized ultrafine particles constituting the granule.
2A, 2B, 2C, 2D, 2E, 2F, 2G, and 2H are X-ray diffraction spectroscopy of lithium manganese phosphate prepared in Examples 1, 4, 5, 8, 9, 12, 13, and 14, respectively. The results of Rietveld refinement on the (XRD) pattern are shown.
Graphs (a) to (u) of FIG. 3 are X-ray diffraction spectroscopy (XRD) patterns of the compounds prepared in Examples 1 to 21, respectively.
4A, 4B, 4C, 4D, and 4E are Example 1 and Comparative Example 1 (FIG. 4A), Example 5 and Comparative Example 5 (FIG. 4B), Example 9 and Comparative Example 9 (FIG. 4C), and Examples. The impedances of the lithium transition metal phosphate compounds prepared in Example 13, Comparative Example 13 (FIG. 4D), Example 14, and Comparative Example 14 (FIG. 4E) are compared.
5A, 5B, 5C, 5D, and 5E are Examples 1 and Comparative Example 1 (FIG. 5A), Example 5 and Comparative Example 5 (FIG. 5B), Example 9, and Comparative Example 9 (FIG. 5C), respectively. The lithium transition metal phosphate compounds prepared in Example 13 and Comparative Example 13 (FIG. 5D), Example 14 and Comparative Example 14 (FIG. 5E) were measured by using the galvanostatic intermittent titration technique (GITT) method in various charging and discharging states. One lithium ion diffusion coefficient is shown.
6 shows the molar ratio (P / M) of the anion PO ₄ to M in terms of the lithium ion diffusion coefficient of lithium manganese cobalt nickel iron prepared in Examples 14, 18, 19, 20, and 21 and Comparative Examples 14 and 15; A graph organized by variables.
7A, 7B, and 7C are charge and discharge graphs of a lithium secondary battery using the anion deficient lithium manganese phosphate prepared in Examples 1, 2, and 3, respectively, as a positive electrode active material.
8 is a comparative graph of charge and discharge of a lithium secondary battery using lithium manganese phosphate prepared in Example 2 (graph (a)) and Comparative Example 2 (graph (b)) as a positive electrode active material.

In the compound according to the present invention represented by Li _{1 - x} M (PO ₄ ) _1-y (0 ≦ _x ≦ 0.15, 0 < _y ≦ 0.05), the molar ratio of M as a cation is 1, and the molar ratio of anion PO ₄ is An anion-deficient non-stoichiometric lithium transition metal phosphate compound of less than 1, which is different from the conventional lithium transition metal phosphate compound in terms of composition and structure.

In the formula (1), the range of the lithium ion molar ratio is for lithium ions as a constituent of the anion deficient lithium transition metal phosphate compound. In fact, when preparing a lithium transition metal phosphate compound as an electrode active material, in order to compensate lithium volatilized during the calcination process or maximize a discharge capacity of a lithium secondary battery, an excess lithium precursor is generally introduced as a reactant. The molar ratio of lithium ions contained in the phosphate compound may be higher than the molar ratio of lithium ions in the above formulas. However, lithium ions introduced for the above purpose are not contained in the anion-deficient lithium transition metal phosphate compound according to the present invention, but exist in the form of impurities having electrochemical activity. A representative example is lithium ions present in the form of crystal surface defects.

In Formula 1, y corresponds to the amount of anion vacancy, and as the vacancy of the anion PO ₄ is generated, the average oxidation number of M or the amount of +1 valent lithium ions is reduced to satisfy the charge neutrality. For example, in the stoichiometric lithium transition metal phosphate compound LiMPO ₄ , if the porosity of the anion PO ₄ is produced without changing the average oxidation number of M, Li is a positive amount of PO ₃ reduced to satisfy the charge neutrality. Should be reduced by a factor This formation of the vacancy between the anion PO ₄ and the triple cation Li together is called the Schottky defect and is one of the typical cavitation mechanisms. According to this mechanism, x = 3y is satisfied and thus 0 <x ≦ 0.15 when 0 <y ≦ 0.05. However, in the anion-depleted lithium transition metal phosphate compound of the present invention, since the oxidation number of M may change, x and y may change independently of each other without satisfying the relationship of x = 3y. That is, regardless of the range of y, x may have a value less than 0, or may have a value greater than 0.15. For example, it may be in the range -1 <x <1. However, in consideration of structural, chemical stability and electrochemical activity in the manufacturing and application process, the preferred range of x is 0 ≦ x ≦ 0.15.

In Formula 1, y representing the amount of anion vacancy is 0 <y ≦ 0.05. In the case of y ≦ 0, the compound is not an anion deficient compound, and in the case of y> 0.05, the structure of the compound may be unstable and thus the electrochemical activity may be lowered. Moreover, the preferable range of y is 0.01≤y≤0.05, the range of more preferable y is 0.02≤y≤0.05, and the most preferable range of y is 0.03≤y≤0.05.

In Formula 2, M ^A has an oxidation number of +2, M ^B has an oxidation number of +3. On the other hand, Fe generally has oxidation numbers of +2 and +3, and M ^T may have various oxidation numbers of +1 to +7. Therefore, depending on the content of M ^A , M ^B , M ^T , Fe, the oxidation number of M ^T and Fe is changed to satisfy the charge neutrality. If the average oxidation number of M composed of cations having different oxidation numbers is v, when 0 ≦ x ≦ 0.15 and 0 <y ≦ 0.05, the average oxidation number v of M is 1.85 ≦ v <2.15. If 0.01 ≦ y ≦ 0.05, 1.85 ≦ v ≦ 2.12, 0.02 ≦ y ≦ 0.05, 1.85 ≦ v ≦ 2.09, and 0.03 ≦ y ≦ 0.05, 1.85 ≦ v ≦ 2.06. When the average oxidation number of M ^T is v ^T , and the average oxidation number of Fe is v ^F , v is expressed as in Equation 1 below, and M ^A , M ^B , M ^T , The content of Fe and the oxidation number of M ^T and Fe are limited.

(Formula 1) v = 2a + 3b + v ^T t + v ^F {1- (a + b + t)}

When all of Fe is +2, v ^F = 2, and v may be simply expressed as in Equation 2 below. (In the Formula 1, The average oxidation number of M v ^{T T} + 1 close to the greater the possibility contain Fe +3 valence, there can not use the Equation 2 for containing the Fe ^{+ 3.)}

(Formula 2) v = b + (v ^T -2) t + 2

Group 2 elements constituting M ^A enhances the stability of the crystal structure, thereby improving chemical stability and lifespan characteristics. Preferably, M ^A is at least one element selected from Mg and Ca, more preferably Mg. Since M ^A has an oxidation number of +2, the compound may have a stable structure when the M ^A content a is 0 ≦ a ≦ 1. However, when a = 1, since the compound does not have electrochemical activity and is not useful as an electrode active material, the range of a is limited to 0 ≦ a <1. The preferred range of a is 0 ≦ a ≦ 0.30, more preferably 0 ≦ a ≦ 0.15.

The Group 13 element constituting M ^B lowers the average oxidation number of the transition metal M ^T , prevents oxidation, improves electrochemical activity, and suppresses generation of impurities. Preferably, M ^B is at least one element selected from B, Al, and Ga, more preferably Al. Since M ^B has an oxidation number of +3, it cannot be employed above a certain level. In the formulas (1) and (2), when M ^B can be dissolved to the maximum, when the average oxidation number of M ^T is +1, where 0 ≦ x ≦ 0.15 and 0 <y ≦ 0.05, the upper limit of M ^B content b Is 0.575. Preferred range of b is 0 ≦ b ≦ 0.20, more preferably 0 ≦ b ≦ 0.10.

M ^T is one or more elements selected from the group consisting of Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, which are 4-5 cycle transition metal elements except Fe. to be. The transition metal has various oxidation numbers and electrochemical activities of +1 to +7, and most of the essential properties (such as theoretical capacity and voltage) of the electrode active material are greatly influenced by what the transition metal is. Therefore, M ^T can be configured according to the use of the battery system to be used. Preferably, M ^T is at least one element selected from Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, Mo, and more preferably one kind selected from Mn, Co, Ni The above element.

Anion-depleted lithium transition metal phosphate compound according to the present invention is a group consisting of Group 2 elements, Group 13 elements, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo At least one element selected from must be included. Preferably, the anion-depleted lithium transition metal phosphate compound according to Formula 1 is crystalline, and may exhibit various crystal structures according to the arrangement of the polyacid anion PO ₄ , which is a tetragonal structure, but has an olivine structure. Is particularly preferred.

The anion-depleted lithium transition metal phosphate compound according to the present invention can be used as an electrode active material of capacitors and other electrochemical devices, including secondary batteries, memory devices, and hybrid capacitors (P-EDLC), in particular, secondary batteries It is suitable as a positive electrode active material of.

The electrode can be prepared by conventional methods known in the art. For one example thereof, an electrode may be prepared by mixing an binder with an anion deficient lithium transition metal phosphate compound as a cathode active material and preparing an electrode slurry, and coating the prepared electrode slurry on a current collector. At this time, a conductive material can also be used.

The present invention provides an electrochemical device comprising (a) an anode comprising an anion-deficient lithium transition metal phosphate compound, (b) a cathode, (c) a separator, and (d) an electrolyte. The electrochemical device of the present invention may be prepared by, for example, inserting a porous separator between an anode and a cathode by a conventional method known in the art and introducing an electrolyte. The negative electrode, the separator, and the electrolyte to be applied together with the positive electrode of the present invention are not particularly limited, and conventional ones that may be used in the conventional electrochemical device may be used. The electrochemical device provided by the present invention includes all devices that undergo an electrochemical reaction, and specific examples thereof include various secondary batteries, memory devices, and capacitors including hybrid capacitors. In particular, a lithium secondary battery including a lithium metal secondary battery, a lithium ion secondary battery, a lithium ion polymer secondary battery or a lithium metal polymer secondary battery among the secondary batteries is preferable. Since the anion-depleted lithium transition metal phosphate compound according to the present invention has higher ion conductivity and higher physical and chemical stability than conventional lithium transition metal phosphate compounds, high capacity, high output, long life and improved output power of the battery using the same Not only can the characteristics be improved, but also a more homogeneous electrode plate can be produced, thereby reducing the battery manufacturing failure rate.

The anion-depleted lithium transition metal phosphate compound according to the present invention may be prepared by changing the reactant mixture ratio, reaction temperature, reaction pressure and the like based on hydrothermal synthesis using subcritical water or supercritical water. Using the manufacturing process of the present invention, it can be treated for several seconds at high temperature and high pressure to form an anion-deficient lithium transition metal phosphate compound. In addition, since the lithium component is already contained before the calcination step, a separate process for mixing with the lithium precursor is not necessary in the calcination step, and the heat treatment time required for the lithium diffusion is not necessary, so that the final electrode active material manufacturing time can be shortened. Can be. In particular, the lithium transition metal phosphate compound is advantageous because the particle size is small because the electron conductivity and ionic conductivity is low, and according to the manufacturing process of the present invention can produce ultra-fine particles without a separate ultra-fine atomization process, it is easy to commercialize . In the subcritical water and supercritical water, the crystallization of the lithium transition metal phosphate compound proceeds very quickly. Therefore, when a phosphate compound having a higher solubility than that of the metal precursor is used, the phosphate compound participates in the crystallization relatively little and releases the pores of the phosphate anion. Easy to create Therefore, the anion-deficient lithium transition metal phosphate compound can be easily produced through the manufacturing process of the present invention.

Specifically, the anion-depleted lithium transition metal phosphate compound according to the present invention may be prepared according to a method comprising the following steps.

(a) mixing a precursor of metal M, a phosphate compound, an alkalizing agent, and a lithium precursor to produce a lithium transition metal phosphate precursor;

(b) mixing the lithium transition metal phosphate precursor of step (a) with water under reaction conditions of temperature 200 ~ 700 ℃, pressure 180 ~ 550bar to synthesize an anion deficient type lithium transition metal phosphate compound, and synthesized Drying;

(c) calcining the result of step (b) or calcining after granulation.

Each step will be described in more detail below.

Step (a) : A precursor of metal M, a phosphate compound, an alkalizing agent, and a lithium precursor are mixed to generate a lithium transition metal phosphate precursor

The precursor of the metal M is not particularly limited as long as it is a compound capable of ionizing as salts containing M of Formula (1). It is preferably a water-soluble compound. Non-limiting examples of such metal precursors include nitrates, sulfates, acetates, carbonates, oxalates, halides, oxides, hydroxides, alkoxides, and mixtures thereof containing M. In particular, nitrates, sulfates, acetates are preferable.

The phosphoric acid compound is not particularly limited as long as it can be ionized as a compound containing a phosphate anion. It is preferably a water-soluble compound. Non-limiting examples of the phosphate compound include phosphoric acid, ammonium phosphate, ammonium hydrogen phosphate, lithium phosphate, phosphate containing one or more of the constituent elements of M in Formula 1, and mixtures thereof. In particular, phosphoric acid is preferred.

The alkalizing agent is not particularly limited as long as the reaction solution is made alkaline. Non-limiting examples of the alkalizing agent include alkali metal hydroxides, alkaline earth metal hydroxides, ammonium hydroxide, ammonium salts, tetra-alkyl ammonium hydroxide (TRAH), and mixtures thereof. In particular, alkali metal hydroxide and ammonium hydroxide are preferable.

As the lithium precursor, any water-soluble salt containing lithium and ionizing can be used without limitation, and non-limiting examples thereof include lithium hydroxide, lithium nitrate, lithium sulfate, lithium acetate, and mixtures thereof. In particular, lithium hydroxide is preferred because it not only serves as a lithium source but also increases alkalinity.

In step (a), Li / M, which is the ratio of the number of moles of Li contained in the lithium precursor and the number of moles of M contained in the precursor of the metal M, is suitably 1.0 to 20, preferably 1.0 to 10. When the Li / M is too small, only a small amount of lithium participates in the synthesis reaction of the lithium transition metal phosphate compound, so that the precursor of the metal M, which has not reacted with lithium, generates impurities such as an oxide, for example. The purity of the will be lowered. On the other hand, when the molar ratio is too large, economical efficiency is lowered because excessively added lithium has to be recovered or discarded from the discharge liquid.

In step (a), the alkali equivalent ratio of the mixture of the metal M precursor, the phosphate compound, the alkalizing agent, and the lithium precursor is preferably 1 to 10, but is not limited thereto. An alkali equivalent ratio is defined as the ratio of the equivalent number of hydroxide ions contained in the said mixture, and the equivalent number of acidic groups (nitrate group, sulfuric acid group, etc.). When the alkali equivalence ratio is too small, impurities are present in the product, and when the alkali equivalence ratio is too large, the alkaline component of the wastewater becomes excessively high.

When mixing the precursor of metal M, a phosphate compound and an alkalizing agent, and a lithium precursor, the mixing method and order of these are not restrict | limited. For example, these may be mixed with water at once or added to water, respectively, or the metal M precursor and the phosphate compound may be first mixed with the alkalizing agent and the lithium precursor, and then mixed with water.

Step (b) : mixing the lithium transition metal phosphate precursor with water under subcritical or supercritical reaction conditions to synthesize an anion deficient lithium transition metal phosphate compound, and drying the synthesized compound

The reaction pressure and reaction temperature should be suitable for the production of the anion deficient lithium transition metal phosphate compound of the specified composition. In the present invention, the subcritical or supercritical condition means a pressure of 180 to 550 bar at a temperature in the range of 200 to 700 ° C., it is appropriate to maintain this condition appropriately, and a continuous reactor is preferable. If the reaction temperature is less than 200 ℃ unsuitable to obtain a single-phase high crystalline anion-deficient lithium transition metal phosphate compound, if the temperature is higher than 700 ℃ increases the cost of the manufacturing apparatus. Alkali metal hydroxides such as lithium, sodium, and potassium have high solubility in water at room temperature and atmospheric pressure, but when the density of water decreases due to high temperature and high pressure, the solubility decreases significantly. In the case of lithium hydroxide, it is necessary to maintain a temperature of 200 to 700 ° C. and a pressure of 180 to 550 bar together to significantly reduce the solubility.

Moreover, it is preferable that pH at the time of reaction is larger than 4.0 and 12.0 or less. If the pH is 4.0 or less, it is not preferable because the produced anion-deficient lithium transition metal phosphate compound is dissolved in the low pH range. On the other hand, if the pH exceeds 12.0, it is economical because by-product formation, equipment corrosion, waste of alkalizing agent is caused, and additional process for washing and draining of excess alkalizing agent is required. Degrades.

Mixing is also suitable for continuous mixers, such as in the form of tubes. In such a mixer, the anion deficient lithium transition metal phosphate compound is formed homogeneously.

The reaction product is then cooled, concentrated and dried. Before drying the concentrate, it may be washed with clean water to remove the impurity salts, ionic impurities that may remain in the concentrate.

The average particle size of the anion-depleted lithium transition metal phosphate compound produced in step (b) is 0.01-5 μm. Preferably it is 0.01-1 micrometer, More preferably, it is 0.01-0.5 micrometer.

Step (c) : calcined the dried resultant of step (b), or calcined after granulation

In the step (c), the anion-depleted lithium transition metal phosphate produced in step (b) is not suitable for use as a cathode active material of a lithium secondary battery due to insufficient crystallinity and very small average primary particle size. The crystallinity is improved and appropriately sized granules are made suitable for use as the active material. It is appropriate that the positive electrode active material of the lithium secondary battery has an average particle size of about 1 to 100 µm in size of a granule.

Granulation may be performed simultaneously with drying, and may be performed using various methods known in the art, such as spray drying, fluidized bed drying, and vibration drying. Spray drying is preferred because it can form spherical granules and increase the tab density of the granules.

In addition, calcination improves the crystallinity of the anion deficient lithium transition metal phosphate compound and improves the adhesion between the crystals. Calcination is preferably carried out immediately after step (b). Particularly, when the granulation and calcining steps are continuously performed, the primary particles constituting the granules are grown while being crystallographically stabilized. If the calcination process is not performed, lithium iron phosphate crystals are not stabilized and the unstable surface collapses, resulting in poor initial charge / discharge performance of the battery, and a low specific surface area and low tap density. As the volume per volume is low, it is not preferable.

Although there is no restriction | limiting in particular as a range of calcination temperature and time, 300-1200 degreeC and 1 to 48 hours are preferable. If the calcination temperature is too low or the calcination time is too short, sintering between the primary particles may not sufficiently occur, so that the primary particles have low crystallinity, a large specific surface area, and low electrode tap density. In addition, low-crystalline lithium iron phosphate is changed to a different material during the charge and discharge process, the battery performance such as charge and discharge capacity, battery life, output, etc. are reduced. On the other hand, if the calcination temperature is too high or the calcination time is long, disadvantages such as phase decomposition are caused as a result of excessive sintering, and the process cost is increased. There is no particular limitation as to the calcination atmosphere, but an inert or reducing atmosphere is preferred in order to prevent oxidation of the transition metal.

A binder, a sintering aid, a dopant, a coating agent, a reducing agent, an oxidizing agent, a carbon precursor, a metal oxide, and lithium before, after, or during one or more of the steps (a), (b), and (c) of the manufacturing step. One or more additives selected from the group consisting of compounds may be additionally added.

The binder may be used for sphericalization of the granules and for improving particle size, and non-limiting examples thereof include water, ammonia water, polyvinyl alcohol (PVA), and mixtures thereof.

Sintering aids can be used to lower the firing temperature or increase the sintering density when firing the granules at high temperatures, non-limiting examples of which include metal oxides and precursors thereof, such as boron oxide, magnesium oxide, aluminum oxide, and the like; And lithium compounds such as lithium fluoride, lithium hydroxide, lithium carbonate and precursors thereof.

Doping agents and coating agents are used to improve the durability of the anion-deficient lithium transition metal phosphate compound. Non-limiting examples thereof include metal oxides such as magnesium oxide, aluminum oxide, titanium oxide, zirconium oxide and precursors thereof.

Reducing or oxidizing agents can be used to control the atmosphere of each preparation step to a reducing or oxidizing atmosphere. In the case of anion-deficient lithium transition metal phosphate compound, a reducing agent may be appropriately used in the manufacturing process for reasons of improving electron conductivity and suppressing oxidation of the transition metal. Non-limiting examples of reducing agents include hydrazine, sodium phosphite, sodium sulfite, sodium nitrite, potassium iodide, sugar, fructose, oxalic acid, ascorbic acid, hydrogen, carbon, hydrocarbons, and mixtures thereof. Non-limiting examples of oxidants include oxygen, chlorine, bromine, hydrogen peroxide, permanganic acid, permanganate, hypochlorite, chlorate, ozone, and mixtures thereof.

Acids are used to accelerate the reaction. Non-limiting examples of acids include phosphoric acid, pyrophosphoric acid, polyphosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, acetic acid, oxalic acid and their compounds, and mixtures.

The carbon precursor may be coated on the surface of the anion deficient lithium transition metal phosphate compound to be used to improve electron conductivity. Non-limiting examples of carbon precursors include graphite, sugar, fructose, oxalic acid, ascorbic acid, starch, cellulose, polyvinyl alcohol (PVA), polyethylene glycol (PEG), and mixtures thereof.

In order to increase the content of lithium in the anion-deficient lithium transition metal phosphate precursor, a lithium compound may be added in the firing step. Non-limiting examples of such lithium compounds include lithium fluoride, lithium hydroxide, lithium carbonate, lithium nitrate, lithium acetate, and mixtures thereof.

Variables affecting the composition of the anion-deficient lithium transition metal phosphate compound include a mixing ratio of a metal precursor, a phosphate compound, an alkalizing agent, a lithium precursor, and water; PH of the mixed solution; Since there are reaction temperature and reaction pressure, the composition ratio of the compound can be controlled by controlling these variables. There may be optimal combinations of parameters for preparing compounds having a specific composition, but the combination of parameters for obtaining compounds of a particular composition is not limited to one. One of ordinary skill in the art may know, without undue experimentation, any combination of these variables to obtain a specific composition.

The present invention will be described in more detail with reference to Examples and Comparative Examples. However, the following examples are provided to illustrate the present invention, and the scope of the present invention is not limited thereto.

Preparation of Anion Deficiency Compounds in which Metal M is a Combination of Mn and Fe

0.25 mol of manganese sulfate (MnSO ₄ ) and 0.75 mol of iron sulfate (FeSO ₄ ) as precursors of metal M, 1 mol of phosphoric acid as phosphoric acid compound, and 27.8 g of sugar as reducing agent in 1.6 L of water, and as alkalizing agent A second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water as a lithium precursor were prepared.

The two aqueous solutions were treated in the following steps (a), (b) and (c) to prepare anion-deficient lithium manganese phosphate.

Step (a): The two aqueous solutions were pumped continuously by pressurizing to 250 bar at room temperature and mixed in a mixer to produce a slurry containing a lithium transition metal phosphate precursor.

Step (b): pressurizing and pumping ultrapure water heated to 450 ° C. to 250 bar to the precursor slurry of step (a) and mixing in a mixer; The final mixed solution was transferred to a reactor maintained at 380 ° C. and 250 bar and held for 7 seconds, thereby continuously synthesizing a low crystalline anion deficient lithium transition metal phosphate compound; Cool to concentrate; Sugar was mixed as a carbon precursor in this concentrate at a 10% weight ratio relative to the lithium transition metal phosphate compound in the concentrate, followed by drying through a spray dryer to form granules.

Step (c): The dried granules formed through spray drying in step (b) were calcined at 700 ° C. for 10 hours to obtain anion-deficient lithium transition metal phosphate compound having improved crystallinity and improved adhesion between crystals. .

In step (b), the pH of the final mixed solution mixed in the mixer was 8.5.

Scanning electron microscopy (SEM) analysis was performed to evaluate the particle size and shape of the final product. Figure 1a shows a granulated particle size of about 5 ~ 30μm taken by enlarging the granulated particles 1,000 times. FIG. 1B is a magnification of 50,000 times a part of the granules, and shows nanometer-sized ultrafine particles constituting the granules.

FIG. 2A is a result of Rietveld refinement of X-ray diffraction spectroscopy (XRD) pattern of the prepared compound, which is modeled to calculate the occupancy of ions in the unit cell. it was confirmed that the _{Li 0 .89 (Mn 0 .25 Fe} 0 .75) (PO 4) 0.96. (As mentioned above, in order to maximize the discharge capacity of the lithium secondary battery, improve the charging and discharging efficiency, etc., Li is added in an excessive amount during the manufacturing process of the lithium transition metal phosphate compound, and the molar ratio of Li in the composition ratio is added in excess for this purpose. Except for Li, that is, only the amount of Li constituting the constituent of the anion-depleted lithium transition metal phosphate compound according to the present invention is shown.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn and Fe

A first aqueous solution in which 0.50 mol of manganese sulfate, 0.50 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water. .

The two aqueous solutions were subjected to the same methods and conditions as in steps (a), (b) and (c) of Example 1, except that the pH measurements of the final mixtures mixed in the mixer in step (b) were different. Similarly, the pH value is different depending on the type and composition of the raw materials in the other examples described below) to prepare anion-deficient lithium manganese phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .90 (Mn 0 .50 Fe} 0 .50) (PO 4) 0.96.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn and Fe

0.75 mol of manganese sulfate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution of 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water was prepared. .

The two aqueous solutions were treated according to the same methods and conditions as in step (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .90 (Mn 0 .75 Fe} 0 .25) (PO 4) 0.97.

Preparation of Anion Deficiency Compounds in which Metal M is Mn

A first aqueous solution in which 1 mol of manganese sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese phosphate.

Modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product, by calculating the occupancy of the ions in the unit cell, it was confirmed that the compound is Li _0.91 Mn (PO ₄ ) _0.97 . Figure 2b is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

 Preparation of Anion Deficiency Compounds in which Metal M is Combination of Co and Fe

0.25 mol of cobalt nitrate (Co (NO ₃ ) ₂ ) 0.25 mol of iron, 0.75 mol of iron sulfate, 1 mol of phosphoric acid, 27.8 g of sugar dissolved in 1.6 L of water, 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water The dissolved second aqueous solution was prepared.

The two aqueous solutions were treated according to the same methods and conditions as those of Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium cobalt phosphate.

Modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product to calculate the occupancy of ions in the unit cell, the compound is Li _0.91 (Co _0.25 Fe _0.75 ) (PO ₄ ) _0.97 Confirmed. Figure 2c is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Co and Fe

A first aqueous solution in which 0.50 mol of cobalt nitrate, 0.50 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water. .

The two aqueous solutions were treated according to the same methods and conditions as those of Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium cobalt phosphate.

Performing an inductively coupled plasma spectroscopy (ICP) analysis of the final product was confirmed that the compound is a _{Li 0 .91 (Co 0 .50 Fe} 0 .50) (PO 4) 0.97.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Co and Fe

A first aqueous solution containing 0.75 mol of cobalt nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar in 1.6 L of water, and a second aqueous solution of 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water were prepared. .

The two aqueous solutions were treated according to the same methods and conditions as those of Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium cobalt phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .90 (Co 0 .75 Fe} 0 .25) (PO 4) 0.97.

Preparation of Anion Deficiency Compounds in which Metal M is Co

A first aqueous solution in which 1 mol of cobalt nitrate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water.

The two aqueous solutions were treated according to the same methods and conditions as in step (a), (b) and (c) of Example 1 to prepare anion-deficient lithium cobalt phosphate.

Modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product to calculate the occupancy of the ions in the unit cell, it was confirmed that the compound is Li _0.90 Co (PO ₄ ) _0.97 . Figure 2d is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Ni and Fe

0.25 mol of nickel nitrate (Ni (NO ₃ ) ₂ ), 0.75 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water. The dissolved second aqueous solution was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in step (a), (b) and (c) of Example 1 to prepare anion-deficient lithium iron phosphate.

Modeling the results of Rietveld method on the X-ray diffraction spectroscopy (XRD) pattern of the final product to calculate the occupancy of ions in the unit cell, the compound is Li _0.91 (Ni _0.26 Fe _0.74 ) (PO ₄ ) _0.97 Confirmed. Figure 2e is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Ni and Fe

A first aqueous solution in which 0.50 mol of nickel nitrate, 0.50 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution of 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water was prepared. .

The two aqueous solutions were treated according to the same methods and conditions as in step (a), (b) and (c) of Example 1 to prepare anion-deficient lithium iron phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .92 (Ni 0 .50 Fe} 0 .50) (PO 4) 0.97.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Ni and Fe

A first aqueous solution in which 0.75 mol of nickel nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution of 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water was prepared. .

The two aqueous solutions were treated according to the same methods and conditions as in step (a), (b) and (c) of Example 1 to prepare anion-deficient lithium iron phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .92 (Ni 0 .75 Fe} 0 .25) (PO 4) 0.98.

Preparation of Anion Deficiency Compounds in which Metal M is Ni

A first aqueous solution in which 1 mol of nickel nitrate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium nickel phosphate.

Modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product to calculate the occupancy of the ions in the unit cell, it was confirmed that the compound is Li _0.93 Ni (PO ₄ ) _0.98 . Figure 2f is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, and Ni

1/3 mol of manganese sulfate, 1/3 mol of cobalt nitrate, 1/3 mol of nickel nitrate, 1 mol of phosphoric acid, 27.8 g of sugar dissolved in 1.6 L of water, 1.5 mol of ammonia and 2 mol of lithium hydroxide A second aqueous solution dissolved in L was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese phosphate nickel.

By modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product to calculate the occupancy of ions in the unit cell, the compound is Li _0.89 (Mn _0.33 Co _0.33 Ni _0.33 ) (PO ₄ ) _It was confirmed that it is _0.96 . Figure 2g is the result of the Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar dissolved in 1.6 L of water, 1.5 mol of ammonia and 2 mol of lithium hydroxide. A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

By modeling the Rietveld method performed on the X-ray diffraction spectroscopy (XRD) pattern of the final product, and calculating the occupancy of ions in the unit cell, the compound is Li _0.90 (Mn _0.25 Co _0.25 Ni _0.25 Fe _0.25 ) (PO ₄ ) confirmed that it is _0.97 . Figure 2h is the result of Rietveld method for the X-ray diffraction spectroscopy (XRD) pattern.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mg and Fe

0.07 mol of magnesium sulfate (MgSO ₄ ), 0.93 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution of 1.5 mol of ammonia and 2 mol of lithium hydroxide in 1.2 L of water. Was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium magnesium phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the above compound is a _{Li 0 .88 (Mg 0 .07 Fe} 0 .93) (PO 4) 0.96.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mg and Mn

A first aqueous solution in which 0.10 mol of magnesium sulfate, 0.90 mol of manganese sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, and a second aqueous solution in which 1.5 mol of ammonia and 2 mol of lithium hydroxide were dissolved in 1.2 L of water.

The two aqueous solutions were treated according to the same methods and conditions as those of Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium magnesium phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .92 (Mg 0 .10 Mn} 0 .90) (PO 4) 0.97.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Al, Mn, and Fe

0.03 mol of aluminum nitrate (Al (NO ₃ ) ₃ ), 0.78 mol of manganese sulfate, 0.19 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, 1.5 mol of ammonia and 2 mol of lithium hydroxide. A second aqueous solution dissolved in 1.2 L of water was prepared.

The two aqueous solutions were treated according to the same methods and conditions as those of Steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium aluminum manganese phosphate.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .85 (Al 0 .03 Mn} 0 .78 Fe 0 .19) (PO 4) 0.98.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1.1 mol of phosphoric acid, and 27.8 g of sugar dissolved in 1.6 L of water, 1.5 mol of ammonia, and 2 mol of lithium hydroxide. A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

In step (b), the pH of the final mixed solution mixed in the mixer was 7.9.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .94 (Mn 0 .25 Co} 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) 0.98.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1.2 mol of phosphoric acid, 27.8 g of sugar dissolved in 1.6 L of water, 1.5 mol of ammonia, and 2 mol of lithium hydroxide. A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

In step (b), the pH of the final mixed solution mixed in the mixer was 6.6.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .97 (Mn 0 .25 Co} 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) 0.99.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar were dissolved in 1.6 L of water, 2.0 mol of ammonia and 2 mol of lithium hydroxide. A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

In step (b), the pH of the final mixed solution mixed in the mixer was 9.2.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .89 (Mn 0 .25 Co} 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) 0.96.

Preparation of Anion Deficiency Compounds in which Metal M is Combination of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, 27.8 g of sugar in 1.6 L of water, 2.5 mol of ammonia and 2 mol of lithium hydroxide, 1.2 L of water A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

In step (b), the pH of the final mixed solution mixed in the mixer was 9.5.

Subjected to inductively coupled plasma spectroscopy (ICP) analysis of the final product was identified as the compound is a _{Li 0 .86 (Mn 0 .25 Co} 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) 0.95.

Comparative Example 1 : Preparation of a stoichiometric compound consisting of a combination of metal M and Mn and Fe

0.25 mol of manganese oxalate (MnC ₂ O ₄ ) and 0.75 mol of iron oxalate (FeC ₂ O ₄ ) as a metal precursor, 1 mol of diammonium phosphate ((NH 4) ₂ HPO ₄ ) as a phosphate compound, lithium carbonate (Li ₂₎ CO ₃ ) 0.55 mol was prepared.

The raw materials were processed in the following steps (a), (b), and (c) to prepare stoichiometric lithium manganese phosphate by solid state reaction of the prior art.

Step (a): The raw materials were first mixed for 8 hours at a speed of 350 rpm using zirconia ball milling.

Step (b): The first mixture of step (a) is secondly mixed with 32.4 g of a carbon precursor sugar and subjected to a first heat treatment for 6 hours in an argon atmosphere at 500 ° C. to form a carbon-coated low crystalline lithium transition metal. Phosphoric acid compound was obtained.

Step (c): The low crystalline compound of step (b) was subjected to a second heat treatment for 5 hours in an argon atmosphere at 675 ° C. to obtain a high crystalline stoichiometric lithium transition metal phosphate compound.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is a _{Li (Mn 0 .25 Fe 0 .75} ) PO 4.

Comparative Example 2 : Preparation of a stoichiometric compound consisting of a combination of metal M and Mn and Fe

0.50 mol of manganese oxalate, 0.50 mol of iron oxalate, 1 mol of diammonium phosphate, and 0.55 mol of lithium carbonate were prepared.

The raw materials were treated according to the same methods and conditions as those of steps (a), (b) and (c) of Comparative Example 1 to prepare a stoichiometric lithium manganese phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is a _{Li (Mn 0 .50 Fe 0 .50} ) PO 4.

Comparative Example 3 : Preparation of a stoichiometric compound consisting of a combination of metal M and Mn and Fe

0.75 mol of manganese oxalate, 0.25 mol of iron oxalate, 1 mol of diammonium phosphate, and 0.55 mol of lithium carbonate were prepared.

The raw materials were treated according to the same methods and conditions as those of steps (a), (b) and (c) of Comparative Example 1 to prepare a stoichiometric lithium manganese phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is a _{Li (Mn 0 .75 Fe 0 .25} ) PO 4.

Comparative Example 4 : Preparation of the stoichiometric compound wherein the metal M is Mn

1 mol of manganese oxalate, 1 mol of diammonium phosphate, and 0.55 mol of lithium carbonate were prepared.

The raw materials were treated according to the same methods and conditions as those of (a), (b) and (c) of Comparative Example 1 to prepare stoichiometric lithium manganese phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. Inductively coupled plasma spectroscopy (ICP) analysis was performed to confirm that the compound was LiMnPO ₄ .

Comparative Example 5 : Preparation of a stoichiometric compound consisting of a metal M in combination of Co and Fe

0.25 mol of cobalt acetate (Co (CH ₃ CO ₂ ) ₂ ) and 0.75 mol of iron oxalate, 1 mol of monoammonium phosphate (NH ₄ H ₂ PO ₄ ) as a phosphate compound, 0.525 mol of lithium carbonate as a lithium precursor The first aqueous solution dissolved and the second aqueous solution in which 1 mol of citric acid was dissolved in distilled water as a gelling agent and a carbon precursor were prepared.

The two aqueous solutions were treated in the following steps (a), (b) and (c) to prepare stoichiometric lithium cobalt phosphate by the sol-gel method of the prior art.

Step (a): A second aqueous solution was slowly added to the first aqueous solution to form a mixed aqueous solution.

Step (b): The mixed aqueous solution of step (a) was heat-treated until gelled at 70 ° C. to obtain a lithium transition metal phosphate precursor precursor gel.

Step (c): The gel obtained in step (b) was subjected to a first heat treatment for 3 hours in a nitrogen atmosphere at 500 ° C. and a second heat treatment at 675 ° C. for 10 hours to obtain a stoichiometric lithium transition metal phosphate compound.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, she was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound Li (Fe Co _{0 .25 0 .75)} PO _4.

Comparative Example 6 : Preparation of a stoichiometric compound consisting of a metal M in combination of Co and Fe

A first aqueous solution in which 0.50 mol of cobalt acetate, 0.50 mol of iron oxalate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in Steps (a), (b) and (c) of Comparative Example 5 to prepare stoichiometric lithium cobalt phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound Li (Fe Co _{0 .50 0 .50)} PO _4.

Comparative Example 7 : Preparation of a stoichiometric compound consisting of a combination of metal and Co in Fe

A first aqueous solution in which 0.75 mol of cobalt acetate, 0.25 mol of iron oxalate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in Steps (a), (b) and (c) of Comparative Example 5 to prepare stoichiometric lithium cobalt phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound Li (Fe Co _{0 .75 0 .25)} PO _4.

Comparative Example 8 : Preparation of stoichiometric compound wherein Metal M is Co

A first aqueous solution in which 1 mol of cobalt acetate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water were prepared.

The two aqueous solutions were treated according to the same methods and conditions as in Steps (a), (b) and (c) of Comparative Example 5 to prepare stoichiometric lithium cobalt phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. Inductively coupled plasma spectroscopy (ICP) analysis was performed to confirm that the compound was LiCoPO ₄ .

Comparative Example 9 : Preparation of a stoichiometric compound consisting of a metal M in combination of Ni and Fe

0.25 mol of nickel acetate (Ni (CH ₃ CO ₂ ) ₂ ), 0.75 mol of iron oxalate, 1 mol of ammonium monophosphate, 0.525 mol of lithium carbonate in distilled water, and a second solution of 1 mol of citric acid in distilled water. An aqueous solution was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Comparative Example 5 to produce stoichiometric lithium iron phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is _{Li (Ni 0 .25 Fe 0 .75} ) PO 4.

Comparative Example 10 : Preparation of the stoichiometric compound consisting of a metal M in combination with Ni and Fe

A first aqueous solution in which 0.50 mol of nickel acetate, 0.50 mol of iron oxalate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water were prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Comparative Example 5 to produce stoichiometric lithium iron phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is _{Li (Ni 0 .50 Fe 0 .50} ) PO 4.

Comparative Example 11 : Preparation of the stoichiometric compound in which the metal M is a combination of Ni and Fe

A first aqueous solution in which 0.75 mol of nickel acetate, 0.25 mol of iron oxalate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Comparative Example 5 to produce stoichiometric lithium iron phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is _{Li (Ni 0 .75 Fe 0 .25} ) PO 4.

Comparative Example 12 : Preparation of the Stoichiometry Compound Where Metal M is Ni

A first aqueous solution in which 1 mol of nickel acetate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 1 mol of citric acid was dissolved in distilled water were prepared.

The two aqueous solutions were treated according to the same methods and conditions as those of steps (a), (b) and (c) of Comparative Example 5 to prepare a stoichiometric lithium phosphate.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. Inductively coupled plasma spectroscopy (ICP) analysis was performed to confirm that the compound was LiNiPO ₄ .

Comparative Example 13 : Preparation of a stoichiometric compound wherein the metal M is a combination of Mn, Co, and Ni

A first aqueous solution in which 0.3 mol of manganese acetate, 0.3 mol of cobalt acetate, 0.3 mol of nickel acetate, 0.9 mol of ammonium monophosphate, and 0.473 mol of lithium carbonate were dissolved in distilled water, and a second aqueous solution in which 0.9 mol of citric acid was dissolved in distilled water.

The two aqueous solutions were treated in the following steps (a), (b) and (c) to prepare stoichiometric lithium manganese cobalt nickel with a sol-gel method of the prior art.

Step (a): A second aqueous solution was slowly added to the first aqueous solution to form a mixed aqueous solution.

Step (b): The mixed aqueous solution of Step (a) was heat treated until gelled at 80 ° C. to obtain a lithium transition metal phosphate precursor precursor gel.

Step (c): The gel obtained in step (b) was subjected to a first heat treatment for 4 hours in an argon atmosphere at 350 ° C. and a second heat treatment at 600 ° C. for 10 hours to obtain a stoichiometric lithium transition metal phosphate compound.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is a _{Li (Mn 0 .33 Co 0 .33} Ni 0 .33) PO 4.

Comparative Example 14 Preparation of a Stoichiometric Compound in which Metal M is Combination of Mn, Co, Ni, and Fe

A first aqueous solution of 0.25 mol of manganese acetate, 0.25 mol of cobalt acetate, 0.25 mol of nickel acetate, 0.25 mol of iron oxalate, 1 mol of ammonium monophosphate, and 0.525 mol of lithium carbonate in distilled water, and a second solution of 1 mol of citric acid dissolved in distilled water. An aqueous solution was prepared.

The two aqueous solutions were treated in the following steps (a), (b) and (c) to prepare stoichiometric lithium manganese cobalt nickel with a sol-gel method of the prior art.

Step (a): A second aqueous solution was slowly added to the first aqueous solution to form a mixed aqueous solution.

Step (b): The mixed aqueous solution of step (a) was heat treated until gelled at 70 ° C. to obtain a lithium transition metal phosphate precursor precursor gel.

Step (c): The gel obtained in step (b) was subjected to a first heat treatment for 5 hours at 500 ° C. in an argon atmosphere and a second heat treatment at 650 ° C. for 10 hours to obtain a stoichiometric lithium transition metal phosphate compound.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed that by performing the inductively coupled plasma spectroscopy (ICP) analysis of the compound _{Li (Mn 0 .25 Co 0 .25} Ni 0 .25 Fe 0 .25) PO 4.

Comparative Example 15 Preparation of Anion Deficiency Compounds in which Metal M Composed of Mn, Co, Ni, and Fe

0.25 mol of manganese sulfate, 0.25 mol of cobalt nitrate, 0.25 mol of nickel nitrate, 0.25 mol of iron sulfate, 1 mol of phosphoric acid, and 27.8 g of sugar dissolved in 1.6 L of water, 3 mol of ammonia and 2 mol of lithium hydroxide, 1.2 L of water. A second aqueous solution dissolved in was prepared.

The two aqueous solutions were treated according to the same methods and conditions as in steps (a), (b) and (c) of Example 1 to prepare anion-deficient lithium manganese cobalt nickel iron.

Analysis of the X-ray diffraction spectroscopy (XRD) pattern for the final product confirmed the crystalline olivine structure. In addition, it was confirmed subjected to inductively coupled plasma spectroscopy (ICP) analysis that the compound is a _{Li 0 .83 (Mn 0 .25 Co} 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) 0.94.

Measurement and evaluation of characteristics and performance

The properties and performance of the compounds according to the examples were measured and evaluated as follows.

Crystal Structure and Impurity Analysis

X-ray diffraction spectroscopy (XRD) analysis of the compounds prepared in Examples 1 to 21 was carried out to investigate the crystal structure of the compounds and the presence of impurities. Graphs (a) to (u) of FIG. 3 are X-ray diffraction spectroscopy (XRD) patterns of the compounds prepared in Examples 1 to 21, respectively.

Each graph of FIG. 3 shows that the crystal structure of the compounds prepared in Examples 1 to 21 is an olivine structure, and shows that impurities having a structure other than the crystalline structure of the olivine structure are not mixed.

Negative ion vacancy ( vacancy ) Measure

The X-ray diffraction spectroscopy (XRD) pattern was analyzed by Rietveld method to confirm that the actual anion vacancies exist in the non-stoichiometric lithium transition metal phosphate compound of the present invention. 2A, 2B, 2C, 2D, 2E, 2F, 2G, and 2H, respectively, show the X-ray diffraction patterns of the compounds prepared in Examples 1, 4, 5, 8, 9, 12, 13, and 14, respectively. This is the result of the Rietveld method. Tables 1, 2, 3, 4, 5, 6, 7, and 8 are calculated by modeling the crystal structure of the position of the ions in the unit cell determined by performing the Rietveld method and the Rietveld method. It shows the share of Li, Mn, Co, Ni, Fe, and P. In Tables 1 to 8, the x, y, z coordinates of the constituent elements are different from each other because the attraction and repulsion between the constituent elements are changed by Coulomb's law due to the anion vacancy, whereby the crystal structure of the compound is deformed. (deformation).

Rietveld method results for the lithium manganese phosphate prepared in Example 1 atom x y z Share Li 0.00000 0.00000 0.00000 0.8875 Mn 0.97463 0.28200 0.25000 0.2518 Fe 0.97463 0.28200 0.25000 0.7482 P 0.41640 0.09448 0.25000 0.9625

Rietveld method results for the lithium manganese phosphate prepared in Example 4 atom x y z Share Li 0.00000 0.00000 0.00000 0.9109 Mn 0.97961 0.28178 0.25000 1.0000 P 0.41547 0.09124 0.25000 0.9703

Rietveld method results for lithium cobalt phosphate prepared in Example 5 atom x y z Share Li 0.00000 0.00000 0.00000 0.9055 Co 0.97900 0.27800 0.25000 0.2537 Fe 0.97900 0.27800 0.25000 0.7463 P 0.40700 0.08800 0.25000 0.9685

Rietveld method results for lithium cobalt phosphate prepared in Example 8 atom x y z Share Li 0.50000 0.50000 0.50000 0.8962 Co 0.97840 0.27894 0.25000 1.0000 P 0.41680 0.09490 0.25000 0.9654

Rietveld method results for lithium nickel phosphate prepared in Example 9 atom x y z Share Li 0.00000 0.00000 0.00000 0.9109 Ni 0.97362 0.28199 0.25000 0.2616 Fe 0.97362 0.28199 0.25000 0.7384 P 0.41380 0.093640 0.25000 0.9703

Result of Rietveld method on lithium nickel phosphate prepared in Example 12 atom x y z Share Li 0.00000 0.00000 0.00000 0.9325 Ni 0.98250 0.27560 0.25000 1.0000 P 0.41670 0.09430 0.25000 0.9775

Rietveld results of lithium manganese phosphate nickel prepared in Example 13 atom x y z Share Li 0.00000 0.00000 0.00000 0.8916 Mn 0.97252 0.28183 0.25000 0.3333 Co 0.97252 0.28183 0.25000 0.3333 Ni 0.97252 0.28183 0.25000 0.3333 P 0.41110 0.09309 0.25000 0.9638

Rietveld results of lithium manganese phosphate nickel iron prepared in Example 14 atom x y z Share Li 0.00000 0.00000 0.00000 0.8962 Mn 0.97470 0.28161 0.25000 0.2527 Co 0.97470 0.28161 0.25000 0.2456 Ni 0.97470 0.28161 0.25000 0.2532 Fe 0.97470 0.28161 0.25000 0.2485 P 0.41970 0.09474 0.25000 0.9654

The occupancy ratio of each element shown in Tables 1, 2, 3, 4, 5, 6, 7, and 8 is the molar ratio of phosphorus (P), while the molar ratio of M, that is, the sum of the molar ratios of metal elements excluding Li is 1. Shows that it is 0.9625 to 0.9775, less than 1. In addition, inductively coupled plasma spectroscopy (ICP) results analyzed in Examples 2, 3, 6, 7, and 10-21 also showed that the molar ratio of M was 1 while the molar ratio of phosphorus (P) was 0.95 to 0.99, which was less than 1. give. Through this, it was confirmed that the lithium transition metal phosphate compound prepared in Examples according to the present invention is an anion-deficient non-stoichiometric compound. On the other hand, inductively coupled plasma spectroscopy (ICP) analysis of the lithium transition metal phosphate compounds prepared in Comparative Examples 1 to 14, it was confirmed that the molar ratio (M: P) of M and P is a stoichiometric compound of 1: 1.

Electrode resistance and Lithium ion  Diffusion coefficient

Li _{1 - x} M (PO ₄ ) _1-y, an anion _- depleting lithium transition metal phosphate compound of the present invention, has a lithium ion diffusion coefficient superior to that of LiMPO _{4, which} is a stoichiometric lithium transition metal phosphate compound because of its anion vacancy, As a result, when the battery is constructed, the electrode resistance is lower.

Anion lack type lithium transition metal phosphate compound and a stoichiometric lithium transition metal in order to compare the resistance of the electrode between the phosphate compound, the first embodiment of _{Li 0 .89 (Mn 0 .25 Fe} 0 .75) (PO 4) compared to _0.96 example _{1 Li (Mn 0 .25 Fe 0} .75) PO 4, embodiment 5 of the _{Li 0 .91 (Co 0 .25 Fe} 0 .75) (PO 4) 0.97 Comparative example 5 Li (Co _0.25 Fe _0.75) PO _4, example 9 of _{Li 0 .91 (Ni 0 .26 Fe} 0 .74) (PO 4) 0.97 Comparative example 9 of the Li (Ni _0.25 Fe _0.75) of PO _4, example 13 Li _{0. 89 (Mn 0 .33 Co 0 .33} Ni 0 .33) (PO 4) _0.96 and Comparative example _{13 Li (Mn 0.33 Co 0.33 Ni} 0.33) PO 4, example 14 Li _{0 .90} (Mn _{0 .25 Co 0 .25 Ni 0 .25 Fe 0} .25) (PO 4) 0.97 and Comparative example 14 of Li (Mn _{0 .25 0 .25} Co Ni Fe _{0 .25 0 .25)} for the PO ₄ GITT (Galvanostatic Intermittent The potential change and impedance were measured using the Titration Technique. The measured impedances are shown in Figs. 4A, 4B, 4C, 4D, and 4E, respectively, which are Nyquist Plots representing the impedance according to the measurement frequency in a complex plane. In the Nyquist plot, Z 'and Z''represent the real and imaginary parts of the complex impedance Z, respectively. The resistance of the electrode can be calculated by measuring the impedance, and it is possible to know what type of resistance depends on the shape of the Nyquist plot. 4A to 4E show that the electrode resistances of FIGS. 4A to 4E consist of a solid electrolyte interface resistance (SEI resistance) and a charge transport resistance (CT resistance). Able to know.

As shown in Figure _{4a, Li 0 .89 (Mn 0} .25 Fe 0 .75) (PO 4) and the electrode resistance of 294Ω is _0.96, the stoichiometry _{Li (Mn 0 .25 Fe 0 .75} ) PO 4 is 669Ω the bar and from which the _{Li 0 .89 (Mn 0 .25 Fe} 0 .75) (PO 4) 0.96 it can be seen an approximately 2.27-fold superior in terms of electrode resistance. As shown in Figure _{4b, Li 0.91 (Co 0.25 Fe} 0.75) (PO 4) and the electrode resistance of 322Ω is _0.97, the stoichiometry _{Li (Co 0 .25 Fe 0 .75} ) PO 4 is 683Ω the bar, from which the _{Li 0 .91 (Co 0 .25 Fe} 0 .75) (PO 4) 0.97 it can be seen an approximately 2.12-fold superior in terms of electrode resistance. As shown in Figure _{4c, Li 0 .91 (Ni 0} .26 Fe 0 .74) (PO 4) and the electrode resistance of 329Ω is _0.97, the stoichiometry _{Li (Ni 0 .25 Fe 0 .75} ) PO 4 is As a result, it was found that Li _0.91 (Ni _0.26 Fe _0.74 ) (PO ₄ ) _0.97 was about 2.17 times better in terms of electrode resistance. As it is shown in Figure _{4d, Li 0 .89 (Mn 0} .33 Co 0 .33 Ni 0 .33) (PO 4) and the electrode resistance of 313Ω is _0.96, the stoichiometry Li (Mn _{0 .33} Co _{0 .33} Ni _{0 .33)} PO ₄ it can be seen therefrom Li _0.89 717Ω the _{bar, (Mn 0.33 Co 0.33 Ni 0.33} ) (PO 4) 0.96 to around 2.29 times superior in terms of electrode resistance. As shown in Figure _{4e, Li 0 .90 (Mn 0} .25 Co 0 .25 Ni 0 .25 Fe 0 .25) (PO 4) and the electrode resistance of 315Ω is _0.97, the stoichiometry Li (Mn _{0 .25 Co 0 .25 Ni 0 .25 Fe 0} .25) PO 4 is 679Ω the bar, from which _{Li 0.90 (Mn 0.25 Co 0.25 Ni} 0.25 Fe 0.25) (PO 4) 0.97 to know about 2.16 times superior in terms of electrode resistance Can be.

Comparing the electrode resistances, if the anion of the lithium transition metal phosphate compound is insufficient, it can be seen that the electrode resistance is reduced by 2.1 to 2.3 times in common regardless of the composition ratio of the elements constituting M, which is a result of the anion shortage This is because the vacancy of the anion formed as facilitates the diffusion of lithium ions and reduces the electrode resistance. In addition, there is no correlation between the electrode resistance and the composition of M means that the anion vacancy affects the diffusion of lithium ions regardless of the composition of M.

Example 1 of the _{Li 0 .89 (Mn 0 .25 Fe} 0 .75) (PO 4) 0.96 and Comparative Example 1 of _{Li (Mn 0 .25 Fe 0 .75} ) PO 4, Embodiment 5 of the Li _{0 .91 (Co 0 .25 Fe 0 .75)} (PO 4) of _0.97 as in Comparative example _{5 Li (Co 0 .25 Fe 0} .75) of PO _4, example _{9 Li 0.91 (Ni 0.26 Fe 0.74} ) (PO 4) _0.97 as in Comparative example 9 of the _{Li (Ni 0 .25 Fe 0 .75} ) PO 4, embodiment 13 of the _{Li 0.89 (Mn 0.33 Co 0.33 Ni} 0.33) (PO 4) 0.96 Comparative example 13 of Li (Mn _{0 .33 Co 0 .33 Ni 0 .33) PO} 4 of example _{14 Li 0.90 (Mn 0.25 Co 0.25} Ni 0.25 Fe 0.25) (PO 4) 0.97 and of Comparative example _{14 Li (Mn 0 .25 Co 0} .25 Ni 0 _{For .25} Fe _{0 .25} ) PO ₄ , the lithium ion diffusion coefficient was measured under various charge and discharge conditions using the GITT method. Figures 5a, 5b, 5c, 5d, and 5e shows the results, respectively, showing the dependence of the lithium ion diffusion coefficient depending on the lithium ion concentration. 5A to 5E, in the charging process of a battery in which lithium ions inside the active material decrease, the diffusion coefficient of lithium ions gradually increases. This is because as lithium ions decrease, diffusion of lithium ions becomes easier. On the contrary, in the discharging process, lithium ions inside the active material are increased, thereby decreasing the diffusion coefficient of lithium ions.

As shown in Figure _{5a, Li 0 .89 (Mn 0} .25 Fe 0 .75) (PO 4) Lithium-ion diffusion coefficient of _0.96 is ^{2.784 × 10 -10 ~ 7.014 × 10} -9 cm 2 depending on the charge and discharge state / s _{and, Li (Mn 0 .25 Fe 0} .75) of the Li-ion diffusivity is the PO ₄ ^{3.187 × 10 -11 ~ 6.387 × 10} -10 cm 2 / s, from which, Li _0.89 (Mn _0.25 Fe _0.75 ) (PO ₄₎ is _0.96 to know the approximately 4.62 ~ 10.98 times Great according to, lithium ion diffusion coefficients in terms of charge-discharge conditions as compared with the stoichiometric _{Li (Mn 0 .25 Fe 0 .75} ) PO 4. As shown in FIG. 5B, the Li ion diffusion coefficient of Li _0.91 (Co _0.25 Fe _0.75 ) (PO ₄ ) _0.97 is 2.832 × 10 ⁻¹⁰ to 6.497 × 10 ⁻⁹ cm ² / s, depending on the state of charge and discharge. lithium ion diffusion coefficients of _{Co 0 .25 Fe 0 .75) PO} 4 is ^{3.122 × 10 -11 ~ 6.257 × 10} -10 inde cm ² / s, from _{which, Li 0 .91 (Co 0 .25} Fe 0 .75 ) (PO ₄ ) _0.97 is about 5.29 ~ 10.38 times better than the stoichiometric Li (Co _0.25 Fe _0.75 ) PO ₄ in terms of lithium ion diffusion coefficient depending on the state of charge and discharge. As shown in FIG. 5C, the Li ion diffusion coefficient of Li _0.91 (Ni _0.26 Fe _0.74 ) (PO ₄ ) _0.97 is 2.491 × 10 ⁻¹⁰ to 5.877 × 10 ⁻⁹ cm ² / s depending on the state of charge and discharge, and Li ( Ni _{0 .25} Fe _{0 .75)} of the Li-ion diffusivity is the PO ₄ ^{2.989 × 10 -11 ~ 5.990 × 10} -10 cm 2 / s, from _{which, Li 0 .91 (Ni 0 .26} Fe 0 .74 ) (PO ₄ ) _0.97 is about 4.59 ~ 9.81 times better than stoichiometric Li (Ni _0.25 Fe _0.75 ) PO ₄ , depending on the state of charge and discharge in terms of lithium ion diffusion coefficient. As shown in FIG. 5D, the Li ion diffusion coefficient of Li _0.89 (Mn _0.33 Co _0.33 Ni _0.33 ) (PO ₄ ) _0.96 is 1.008 × 10 ⁻⁹ to 9.935 × 10 ⁻⁹ cm ² / s depending on the state of charge and discharge, _{Li (Mn 0 .33 Co 0 .33} Ni 0 .33) of the Li-ion diffusivity is the PO ₄ ^{3.675 × 10 -11 ~ 5.962 × 10} -10 cm 2 / s, from which, Li _{0 .89} (Mn _{0 .33 Co 0 .33 Ni 0 .33)} (PO 4) 0.96 the stoichiometry _{Li (Mn 0.33 Co 0.33 Ni 0.33} ) compared to the PO _4, in terms of lithium ion diffusion coefficient according to the charge and discharge state of about 12.02 ~ 27.43 times Great It can be seen. As shown in FIG. 5E, the Li ion diffusion coefficient of Li _0.90 (Mn _0.25 Co _0.25 Ni _0.25 Fe _0.25 ) (PO ₄ ) _0.97 is 4.140 × 10 ^-10 to 8.415 × 10 ^-9 cm ² / s depending on the state of charge and discharge. and, Li lithium ion diffusion coefficients of _{(Mn 0 .25 Co 0 .25 Ni} 0 .25 Fe 0 .25) PO 4 is the ^{2.998 × 10 -11 ~ 6.962 × 10} -10 cm 2 / s, from which, Li _{0.90 (Mn 0.25 Co 0.25 Ni 0.25} Fe 0.25) (PO 4) 0.97 is compared with the stoichiometric _{Li (Mn 0 .25 Co 0 .25} Ni 0 .25 Fe 0 .25) PO 4, Li-ion diffusivity in the charging and surface It can be seen that it is about 8.39 ~ 13.81 times superior depending on the discharge state.

Through comparison of the lithium ion diffusion coefficient, when the anion of the lithium transition metal phosphate compound is insufficient, it can be seen that the lithium ion diffusion coefficient increases by about 27 times, from which the anion vacancies facilitate the diffusion of lithium ions. It is confirmed that it is effective.

Table 9 shows the lithium ion diffusion coefficients of the anion deficient type lithium transition metal phosphate compounds prepared in Examples 15, 16, and 17 by GITT method. All the same, the lithium ion diffusion coefficient was measured at 40% state of charge (SOC).

Lithium Ion Diffusion Coefficient of the Lithium Transition Metal Phosphate Compounds Prepared in Examples 15-17 Example compound Lithium Ion Diffusion Coefficient (cm ² / s) Example 15 _{Li 0 .88 (Mg 0 .07 Fe} 0 .93) (PO 4) 0.96 2.315 × 10 ^-9 Example 16 _{Li 0 .92 (Mg 0 .10 Mn} 0 .90) (PO 4) 0.97 2.697 × 10 ^-9 Example 17 _{Li (.19 Al 0 .03 Mn 0} .78 Fe 0) 0 .85 (PO 4) 0.98 2.214 × 10 ^-9

From Table 9, it can be seen that even in the case of an anion-depleted lithium transition metal phosphate compound containing a non-transition metal, it has an improved lithium ion diffusion coefficient of 10 ⁻⁹ . In addition, Figures 5a to 5e, and Table 9 shows that, regardless of the composition of M, the vacancy caused by the lack of anion has the effect of facilitating the diffusion of lithium ions.

6 shows the relationship between the molar ratio (P / M) of the anion PO ₄ to M and the lithium ion diffusion coefficient. Here, the lithium ion diffusion coefficient is measured at 40% state of charge (SOC) using the GITT method for the lithium manganese cobalt nickel iron prepared in Examples 14, 18, 19, 20, and 21 and Comparative Examples 14 and 15. It is. As can be seen from FIG. 6, the lithium ion diffusion coefficient can be improved by setting the molar ratio P / M to less than one. In particular, when P / M is 0.95 ≦ P / M ≦ 0.99, the lithium ion diffusion coefficient is better than when P / M = 1, and is more excellent when 0.96 ≦ P / M ≦ 0.98. On the other hand, as the P / M is changed from 0.95 to 0.94, the diffusion coefficient increases rapidly, due to the excessive generation of anionic vacancy and partial collapse of the crystal structure. Since crystal structure collapse lowers the electrochemical activity, it is not desirable to generate excessive anion vacancy.

Charge and discharge  Characterization

Characterization of the lithium secondary battery prepared using the anion-deficient lithium transition metal phosphate compound of the present invention was performed as follows.

The conductive material is a mixture of Super-P ^® (conductive carbon black produced by TIMCAL Graphite & Carbon Inc., Switzerland) and vapor-grown carbon fiber (VGCF) in a weight ratio of 1: 1. As a binder, KF1100 (polyvinylidene fluoride produced by Kureha Chemical Ind. Co., Ltd., Japan) was used, and an anion-deficient lithium transition metal phosphate compound, a conductive material, and a binder had a weight of 90: 5: 5. Mixing in proportions constituted the electrode slurry. The electrode slurry was applied on an aluminum thin film at a rate of 0.3 m / min, and dried at an applicator front chamber temperature of 90 ° C. and a rear chamber temperature of 120 ° C. to prepare a positive electrode. The electrolyte was prepared by dissolving 1 mol of LiPF ₆ in a solvent in which ethylene carbonate (EC): ethyl methyl carbonate (EMC) was mixed in a 1: 2 volume ratio. Coin cell-type lithium secondary batteries were prepared and charged and discharged at 0.1 C rate constant current using a Maccor series 4000.

7A, 7B, and 7C are charge and discharge graphs of a lithium secondary battery using the anion deficient lithium manganese phosphate prepared in Examples 1, 2, and 3, respectively, as a positive electrode active material. When the cutoff voltage of discharge is set to 3.0 V, the discharge capacity of the anion-depleted lithium manganese phosphate according to the present invention is about 136 to 149 mAh / g depending on the content of manganese. Compared with the charging potential, the difference between the charge potential and the discharge potential is narrow. 8 is a comparison of the charge and discharge graph of the lithium secondary battery using the lithium manganese phosphate prepared in Example 2 and Comparative Example 2 as a positive electrode active material, 129 mAh / In contrast to the discharge capacity of g, the anion-depleted lithium manganese phosphate of Example 2 has a higher discharge capacity of about 138 mAh / g.

The anion-depleted lithium transition metal phosphate compound according to the present invention can be used as an electrode active material of capacitors and other electrochemical devices, including secondary batteries, memory devices, and hybrid capacitors (P-EDLC), in particular of secondary batteries It is suitable as a positive electrode active material.

Claims (24)

An anion deficient type lithium transition metal phosphate compound represented by the following Chemical Formula 1, which is an electrode active material.
(Formula 1) Li _{1 - x} M (PO ₄ ) _1-y
In Formula 1, 0 ≦ x ≦ 0.15, 0 <y ≦ 0.05, M is represented by the following Formula 2,
(Formula 2) M ^A _a M ^B _b M ^T _t Fe _{1- (a + b + t)}
In Formula 2, M ^A is at least one element selected from the group consisting of Group 2 elements, M ^B is at least one element selected from the group consisting of Group 13 elements, M ^T is Sc, Ti, At least one element selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, where 0 ≦ a <1, 0 ≦ b <0.575, and 0 ≦ t≤1, 0≤ (a + b) <1, and 0 <(a + b + t) ≤1.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein 0.01 ≦ y ≦ 0.05.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein 0.02 ≦ y ≦ 0.05.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein 0.03 ≦ y ≦ 0.05.
The method according to claim 1, M ^A is at least one element selected from the group consisting of Mg and Ca, M ^B is at least one element selected from the group consisting of B, Al, and Ga, M ^T is Ti, Anion-depleted lithium transition metal phosphate compound which is at least one element selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, and Mo.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein M ^A is Mg, M ^B is Al, and M ^T is at least one element selected from the group consisting of Mn, Co, and Ni.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein 0 ≦ a ≦ 0.30 and 0 ≦ b ≦ 0.20.
The anion deficient lithium transition metal phosphate compound according to claim 1, wherein 0 ≦ a ≦ 0.15 and 0 ≦ b ≦ 0.10.
The anion deficient type lithium transition metal phosphate compound according to claim 1, which has an olivine crystal structure.
A cathode of a secondary battery comprising the anion-depleted lithium transition metal phosphate compound according to any one of claims 1 to 9.
(a) a positive electrode comprising an anion deficient lithium transition metal phosphate compound according to any one of claims 1 to 9,
(b) a cathode,
(c) a membrane, and
(d) electrolyte
Secondary battery comprising a.
(a) mixing a precursor of metal M, a phosphate compound, an alkalizing agent, and a lithium precursor to produce a lithium transition metal phosphate precursor;
(b) mixing the lithium transition metal phosphate precursor of step (a) with water under reaction conditions of temperature 200 ~ 700 ℃, pressure 180 ~ 550bar to synthesize an anion deficient type lithium transition metal phosphate compound, and synthesized Drying;
(c) calcining, or granulating and then calcining the result of step (b),
A method for producing an anion deficient type lithium transition metal phosphate compound represented by Chemical Formula 1, which is an electrode active material.
(Formula 1) Li _{1 - x} M (PO ₄ ) _1-y
In Formula 1, 0 ≦ x ≦ 0.15, 0 <y ≦ 0.05, M is represented by the following Formula 2,
(Formula 2) M ^A _a M ^B _b M ^T _t Fe _{1- (a + b + t)}
In Formula 2, M ^A is at least one element selected from the group consisting of Group 2 elements, M ^B is at least one element selected from the group consisting of Group 13 elements, M ^T is Sc, Ti, At least one element selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, Y, Zr, Nb, and Mo, where 0 ≦ a <1, 0 ≦ b <0.575, and 0 ≦ t≤1, 0≤ (a + b) <1, and 0 <(a + b + t) ≤1.
The method for producing an anion deficient lithium transition metal phosphate compound according to claim 12, wherein 0.01 ≦ y ≦ 0.05.
The method for producing an anion deficient type lithium transition metal phosphate compound according to claim 12, wherein 0.02 ≦ y ≦ 0.05.
The method for producing an anion deficient lithium transition metal phosphate compound according to claim 12, wherein 0.03 ≦ y ≦ 0.05.
Of claim 12 wherein, M ^A is at least one element selected from the group consisting of Mg and Ca, M ^B is at least one element selected from the group consisting of B, Al, and Ga, M ^T is Ti, A method for producing an anion deficient lithium transition metal phosphate compound, which is at least one element selected from the group consisting of V, Cr, Mn, Co, Ni, Cu, Zn, Zr, Nb, and Mo.
The method of claim 12, wherein M ^A is Mg, M ^B is Al, and M ^T is at least one element selected from the group consisting of Mn, Co, and Ni. .
The method for producing an anion deficient lithium transition metal phosphate compound according to claim 12, wherein 0 ≦ a ≦ 0.30 and 0 ≦ b ≦ 0.20.
The method for producing an anion deficient lithium transition metal phosphate compound according to claim 12, wherein 0 ≦ a ≦ 0.15 and 0 ≦ b ≦ 0.10.
The method for producing an anion-depleted lithium transition metal phosphate compound according to claim 12, which has an olivine crystal structure.
The method of claim 12, wherein the pH of the reaction conditions of step (b) is greater than 4.0 and less than or equal to 12.0.
The method for producing an anion deficient lithium transition metal phosphate compound according to claim 12, wherein the primary particle average size of the anion deficient lithium transition metal phosphate compound synthesized in step (b) is 0.01 to 5 µm.
13. The process of claim 12, wherein during (a) to (c), before, after or during one or more of the steps, hydrazine, sodium phosphite, sodium sulfite, sodium nitrite, potassium iodide, sugar, fructose, oxalic acid, ascorbic acid Method for producing an anion-depleted lithium transition metal phosphate compound, characterized in that at least one reducing agent selected from the group consisting of hydrogen, carbon, and hydrocarbons.
13. The process of claim 12, wherein in steps (a) to (c), before, after or during one or more of the steps, graphite, sugar, fructose, oxalic acid, ascorbic acid, starch, cellulose, polyvinyl alcohol (PVA), A method for producing anion-deficient lithium transition metal phosphate compound, characterized in that at least one carbon precursor selected from the group consisting of polyethylene glycol (PEG) is added.

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