KR20160026307A - Positive active material for rechargeable lithium battery, method of preparing the same, and rechargeable lithium battery including the same - Google Patents

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, a producing method thereof, and a lithium secondary battery comprising the same. Provided is the positive electrode active material for a lithium battery in a crystal lattice structure of a compound in which a reversible intercalation and deintercalation of lithium is enabled, wherein a crystal lattice is controlled such that the thickness of an MO slab is large and the thickness of an inter slab is small from a crystal structure analysis by a Rietveld method when using space group R-3m in a crystal structure model on the basis of an x-ray diffraction analysis on the crystal lattice structure of a compound in which a reversible intercalation and deintercalation of lithium is enabled and a crystal lattice is not controlled.

Description

TECHNICAL FIELD The present invention relates to a cathode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same. BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

One embodiment of the present invention relates to a cathode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery including the same.

Recently, with regard to the tendency to miniaturize and lighten portable electronic devices, there is an increasing need for high performance and large capacity of batteries used as power sources for these devices.

Cells generate electricity by using materials that can electrochemically react to the positive and negative electrodes. A typical example of such a battery is a lithium secondary battery that generates electrical energy by a change in chemical potential when intercalation-deintercalation of lithium ions occurs in the positive electrode and the negative electrode .

The lithium secondary battery is manufactured by using a material capable of reversible intercalation-deintercalation of lithium ions as a positive electrode and a negative electrode active material, and filling an organic electrolyte or a polymer electrolyte between the positive electrode and the negative electrode.

As a cathode active material of a lithium secondary battery, a lithium composite metal compound is used. For example, composite metal oxides such as LiCoO ₂ , LiMn ₂ O ₄ , LiNiO ₂ and LiMnO ₂ have been studied.

Of the above cathode active materials, Mn-based cathode active materials such as LiMn ₂ O ₄ and LiMnO ₂ are easy to synthesize and are relatively inexpensive and have excellent thermal stability compared to other active materials in overcharging, However, it has a disadvantage of low capacity.

LiCoO ₂ is a typical cathode active material commercially available and commercially available since it has good electric conductivity, high battery voltage of about 3.7 V, excellent cycle life characteristics, stability and discharge capacity. However, since LiCoO ₂ is expensive, it accounts for more than 30% of the battery price, which causes a problem of poor price competitiveness.

LiCoO ₂ has the highest discharge capacity of the battery among the above-mentioned cathode active materials, but it has a disadvantage that it is difficult to synthesize. In addition, the high oxidation state of nickel causes a decrease in battery life and electrode life, and there is a problem that self discharge is severe and reversibility is low. In addition, it is difficult to commercialize it because the stability is not completely secured.

An embodiment of the present invention provides a cathode active material for a high-output lithium secondary battery having excellent output characteristics, a method for producing the same, and a lithium secondary battery including the same.

One embodiment of the present invention is a crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium,

Based on the X-ray diffraction analysis of the crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium which does not control the crystal lattice by controlling the crystal lattice, the space group R-3m is subjected to a crystal structure model The present invention provides a cathode active material for a lithium battery, which has a large thickness of MO slab and a small thickness of inter slab due to crystal structure analysis by the Rietveld method when used.

At this time, the inter slab / MO slab ratio which is the ratio between the MO slab and the inter slab may be 1.25 or less.

The thickness of the MO slab may be 2.105 to 2.205.

Also, the thickness of the inter slab may be 2.624 to 2.634.

The compound capable of reversible intercalation and deintercalation of lithium controlled by the crystal lattice can be obtained by the Rietveld method when the space group R-3m is used in the crystal structure model based on the X-ray diffraction analysis, The degree of cation mixing can be less than 1.5%.

The compound capable of reversible intercalation and deintercalation of lithium controlled by the crystal lattice may not exhibit an impurity peak in the 7Li MAS NMR analysis.

Further, the compound is _a compound represented by the formula Li _a A _{1 - b} X _b D _{2 (0.90≤a≤1.8,0≤b≤0.5), Li a A 1} - b X b O 2 -c T c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), LiE 1 _{- b} X _b O _{2 - c} D _{c (0≤b≤0.5, 0≤c≤0.05), LiE 2} -b X b O 4-c T c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1 -b- c Co b X _c D _α (0.90 ≦ a ≦ 1.8, 0 ≦ _b ≦ 0.5, 0 ≦ _c ≦ 0.05, 0 ≦ a ≦ 2), Li _a Ni _{1 -b c} Co _b X _c O _{2 -α} T _α ? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni _{1 -b- c} Co _b X _c O _{2 - ?} T ₂ (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni ₁ -bc Mn _b X _c D _? (0.90 _{? A?} 1.8, , 0? C? 0.05, 0??? 2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T _? (0.90 _{? A?} 1.8, 0 _? B _? 0.5, , 0 & lt _{;? &Lt}; 2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T ₂ (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni _b e _c G _d O _{2 - e} T _e (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1 , 0≤e≤0.05), Li a Ni b Co c Mn d G e O 2 - f T f (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5 , 0.001≤e≤0.1, 0≤f≤0.05), Li a NiG b O 2 - c T c (0.90 ≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a CoG b O 2 - c T c (0.90≤a≤ 1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a _{MnG b O 2 - c T c} (0.90≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a Mn 2 G b O 2 -c T c (0.90≤a≤1.8, 0.001≤b ? 0.1, 0? C? 0.05), Li _a MnG _b PO ₄ (0.90? A? 1.8, 0.001? B? 0.1), LiNiVO ₄ , and Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? ₂ ). Wherein A is at least one element selected from the group consisting of Ni, Co, Mn or a combination thereof and X is at least one element selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, , S, P or a combination thereof, E is Co, Mn or a combination thereof, T is F, S, P or a combination thereof, G is a combination of Al, Cr, Mn, Fe, Mg, La , Ce, Sr, V, or combinations thereof, and J is V, Cr, Mn, Co, Ni, Cu, or combinations thereof.

The compound capable of reversible intercalation and deintercalation of lithium may be a lithium nickel cobalt manganese composite oxide.

The lithium nickel cobalt manganese composite oxide is represented by the following general formula (1).

[Chemical Formula 1]

Li [LizA (1-z-a) Da] EbO2-b

Wherein A is at least one element selected from the group consisting of Mg, Al, Zr, B and Ti, E is at least one element selected from the group consisting of P, F and S, 0.05? Z? 0.1, 0? A? 0.05 and 0? B? 0.05, and 0.48??? 0.81, 0.09?? 0.29 and 0.09??

According to another embodiment of the present invention, there is provided a method of manufacturing a lithium secondary battery, comprising: dry-mixing a lithium-supplying material and a transition metal precursor;

The present invention also provides a method for producing a positive electrode active material for a lithium secondary battery.

At this time, in the step of firing the mixture to form the lithium composite compound,

The firing temperature may be 700 to 1,050 占 폚.

The lithium supplying material may be Li2CO3, LiOH, Li2O, Li2O2.

Another embodiment of the present invention is a negative electrode comprising a positive electrode and a negative electrode active material including the above-described positive electrode active material for a lithium secondary battery; And an electrolyte. &Lt; IMAGE &gt;

According to an embodiment of the present invention, there is provided an anode active material for a lithium secondary battery having a high output cell characteristic excellent in output characteristics, a method for producing the same, and a lithium secondary battery including the same.

1 is a schematic view of a lithium secondary battery.
Fig. 2 shows the results of 7Li MAS NMR of Example 1. Fig.
3 shows the results of 7Li MAS NMR of Comparative Example 1. Fig.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited thereto, and the present invention is only defined by the scope of the following claims.

first, In one embodiment of the present invention, in the crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium,

Based on the X-ray diffraction analysis of the crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium which does not control the crystal lattice by controlling the crystal lattice, the space group R-3m is subjected to a crystal structure model The present invention provides a cathode active material for a lithium battery, which has a large thickness of MO slab and a small thickness of inter slab due to crystal structure analysis by the Rietveld method when used.

More specifically, the cathode active material controlling the crystal lattice can improve the battery characteristics of the lithium secondary battery. More specifically, according to one embodiment of the present invention, a cathode active material having controlled crystal lattice can provide a cathode active material having a high output characteristic improved in an output characteristic than a cathode active material not controlling a crystal lattice.

The inter slab / MO slab ratio which is the ratio of the MO slab and the inter slab may be 1.25 or less.

The thickness of the MO slab may be 2.105 to 2.205.

The thickness of the inter slab may be 2.624 to 2.634.

The above MO slab and inter slab can be confirmed by XRD Rietveld Refinement analysis, and the interaction of the metal ions in the MO 6 octahedral crystal structure, which is a crystal structure, will be reduced by the change of the MO slab, and the change of the MO slab and the inter slab The cathode active material controlled by the crystal lattice exhibits an improved effect in terms of reversible migration of Li ions and cell conductivity, thereby providing a high output cathode active material.

The compound capable of reversible intercalation and deintercalation of lithium controlled by the crystal lattice can be obtained by Rietveld method using the space group R-3m in a crystal structure model based on X-ray diffraction analysis method, the cation mixing degree may be 1.5% or less. Cation mixing is present in the Li layer at the same ion as Ni, so that the degree of reduction of intercalation and deintercalation of lithium can be known. As described above, the cathode active material having the crystal lattice control has a low value of less than 1.5% Li can help reversible migration.

In addition, a compound capable of reversible intercalation and deintercalation of lithium controlled by the crystal lattice may not exhibit an impurity peak in the 7Li MAS NMR analysis. The 7Li MAS NMR analysis shows that the cathode active material having the crystal lattice controlled therein has no impurity peak, the degree of shift of the peak is also small, and the broadness of the peak becomes large, thereby decreasing the crystallinity at the surface. This is expected to increase the crystallinity in the bulk in the XRD analysis and to control the crystallinity of cubic crystals without excessive crystallinity on the surface.

For example, the compound capable of reversible intercalation and deintercalation of lithium may be Li _a A _{1 - b} X _b D ₂ (0.90? A? 1.8, _{0 ? B?} 0.5), Li _a A _{1 - b} X _b O _{2 - c} T _c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), LiE 1 - b X b O 2 - c D c (0 _{? B?} 0.5, 0 _{? C?} 0.05), LiE _{2 - b} X _b O _{4 - c} T _c (0 _? B _? 0.5, 0 _? C _? 0.05), Li _a Ni _{1 -b - c} Co _b X _c D _? (0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, _{≤2), Li a Ni 1 -b-} c Co b X c O 2 -α T α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <α <2), Li a Ni _1-bc Co _b X _c O _2-α T ₂ (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0 <α <2), Li a Ni 1 -b- c Mn b X c D α (0.90≤a≤1.8, 0≤b ? 0.5, 0? C? 0.05, 0??? 2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T _? (0.90 _{? A?} 1.8, 0 _? B _? 0.5, ? 0.05, 0 <? <2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T ₂ (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni _b e _c G _d O _{2 - e} T _e (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1 , 0≤e≤0.05), Li a Ni b Co c Mn d G e O 2 - f T f (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5 , 0.001≤e≤0.1, 0≤e≤0.05), Li a NiG b O 2 - c T c (0.90 ≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a CoG b O 2 - c T c (0.90≤a≤ 1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a _{MnG b O 2-c T c} (0.90≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a Mn 2 G b O 2 - c T c (0.90? A? 1.8, 0.001? B? 0.1, 0? C? 0.05), Li _a MnG _b PO ₄ (0.90? A? 1.8, 0.001? B? 0.1), LiNiVO ₄ , and Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? ₂ ).

Wherein A is at least one element selected from the group consisting of Ni, Co, Mn or a combination thereof and X is at least one element selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, Wherein E is Co, Mn or a combination thereof, T is F, S, P or a combination thereof, and G is at least one element selected from the group consisting of Al, Cr, Mn, Fe, Mg , La, Ce, Sr, V, or combinations thereof, and J may be V, Cr, Mn, Co, Ni, Cu, or combinations thereof.

The compound capable of reversible intercalation and deintercalation of lithium may be a lithium nickel cobalt manganese composite oxide.

The lithium nickel cobalt manganese composite oxide is represented by the following general formula (1).

[Chemical Formula 1]

Li [LizA (1-z-a) Da] EbO2-b

Wherein A is at least one element selected from the group consisting of Mg, Al, Zr, B and Ti, E is at least one element selected from the group consisting of P, F and S, 0.05? Z? 0.1, 0? A? 0.05 and 0? B? 0.05, and 0.48??? 0.81, 0.09?? 0.29 and 0.09??

According to another embodiment of the present invention, there is provided a method of manufacturing a lithium secondary battery, comprising: dry-mixing a lithium-supplying material and a transition metal precursor;

The present invention also provides a method for producing a positive electrode active material for a lithium secondary battery.

At this time, in the step of firing the mixture to form the lithium composite compound,

The firing temperature may be 700 to 1,050 占 폚.

Here, when the firing temperature is lower than 700 캜, rapid deterioration of the battery characteristics at normal temperature and high temperature may occur. If the firing temperature is higher than 1,050 占 폚, the capacity and capacity retention rate may be drastically lowered.

The lithium supplying material may be Li2CO3, LiOH, Li2O, Li2O2.

The description of the manufactured positive electrode active material is the same as that of the embodiment of the present invention described above, so a detailed description thereof will be omitted.

In still another embodiment of the present invention, there is provided a lithium secondary battery including a positive electrode, a negative electrode and an electrolyte, wherein the positive electrode includes a current collector and a positive electrode active material layer formed on the current collector, A lithium secondary battery comprising a positive electrode active material.

The description related to the cathode active material is the same as that of the above-described embodiment of the present invention, and thus will not be described.

The cathode active material layer may include a binder and a conductive material.

The binder serves to adhere the positive electrode active material particles to each other and to adhere the positive electrode active material to the current collector. Typical examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl Polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-acrylonitrile, styrene-butadiene rubber, Butadiene rubber, acrylated styrene-butadiene rubber, epoxy resin, nylon, and the like, but not limited thereto.

The conductive material is used for imparting conductivity to the electrode. Any conductive material can be used without causing any chemical change in the battery. Examples of the conductive material include natural graphite, artificial graphite, carbon black, acetylene black, Carbon-based materials such as black and carbon fiber; Metal powders such as copper, nickel, aluminum, and silver, or metal-based materials such as metal fibers; Conductive polymers such as polyphenylene derivatives; Or a mixture thereof may be used.

The negative electrode includes a current collector and a negative active material layer formed on the current collector, and the negative active material layer includes a negative active material.

The negative electrode active material includes a material capable of reversibly intercalating / deintercalating lithium ions, a lithium metal, an alloy of lithium metal, a material capable of doping and dedoping lithium, or a transition metal oxide.

As a material capable of reversibly intercalating / deintercalating lithium ions, any carbonaceous anode active material commonly used in lithium ion secondary batteries can be used as the carbonaceous material. Typical examples thereof include crystalline carbon , Amorphous carbon, or a combination thereof. Examples of the crystalline carbon include graphite such as natural graphite or artificial graphite in the form of amorphous, plate-like, flake, spherical or fibrous type. Examples of the amorphous carbon include soft carbon (soft carbon) Or hard carbon, mesophase pitch carbide, fired coke, and the like.

As the lithium metal alloy, a lithium-metal alloy may be selected from the group consisting of lithium, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, An alloy of a selected metal may be used.

As the material capable of doping and dedoping lithium, Si, SiOx (0 <x <2), Si-Y alloy (Y is an alkali metal, an alkali earth metal, a Group 13 element, a Group 14 element, Sn, Sn-Y (wherein Y is at least one element selected from the group consisting of alkali metals, alkaline earth metals, Group 13 elements, Group 14 elements, transition metals, rare earth elements, and combinations thereof) Or an element selected from the group consisting of combinations thereof, but not Sn), and at least one of them may be mixed with SiO2. The element Y may be at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Se, Te, Po, and combinations thereof.

Examples of the transition metal oxide include vanadium oxide, lithium vanadium oxide, and the like.

The negative electrode active material layer also includes a binder, and may optionally further include a conductive material.

The binder serves to adhere the anode active material particles to each other and to adhere the anode active material to the current collector. Typical examples thereof include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl chloride, Such as polyvinyl chloride, polyvinyl fluoride, polymers comprising ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, Styrene-butadiene rubber, epoxy resin, nylon, and the like may be used, but the present invention is not limited thereto.

The conductive material is used for imparting conductivity to the electrode. Any conductive material can be used without causing any chemical change in the battery. Examples of the conductive material include natural graphite, artificial graphite, carbon black, acetylene black, Carbon-based materials such as black and carbon fiber; Metal powders such as copper, nickel, aluminum, and silver, or metal-based materials such as metal fibers; Conductive polymers such as polyphenylene derivatives; Or a mixture thereof may be used.

The collector may be selected from the group consisting of a copper foil, a nickel foil, a stainless steel foil, a titanium foil, a nickel foam, a copper foil, a polymer substrate coated with a conductive metal, and a combination thereof.

As the current collector, Al may be used, but the present invention is not limited thereto.

The negative electrode and the positive electrode are prepared by mixing an active material, a conductive material and a binder in a solvent to prepare an active material composition, and applying the composition to a current collector. The method of manufacturing the electrode is well known in the art, and therefore, a detailed description thereof will be omitted herein. As the solvent, N-methylpyrrolidone or the like can be used, but it is not limited thereto.

The electrolyte includes a non-aqueous organic solvent and a lithium salt.

The non-aqueous organic solvent serves as a medium through which ions involved in the electrochemical reaction of the battery can move.

The non-aqueous organic solvent may be a carbonate, ester, ether, ketone, alcohol, or aprotic solvent. Examples of the carbonate solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC) EC), propylene carbonate (PC), and butylene carbonate (BC) may be used. As the ester solvent, methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate ,? -butyrolactone, decanolide, valerolactone, mevalonolactone, caprolactone, and the like can be used. Examples of the ether solvent include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, and tetrahydrofuran. As the ketone solvent, cyclohexanone may be used have. As the alcoholic solvent, ethyl alcohol, isopropyl alcohol and the like can be used. As the aprotic solvent, R-CN (R is a linear, branched or cyclic hydrocarbon group having 2 to 20 carbon atoms, , A double bond aromatic ring or an ether bond), and dioxolanes such as 1,3-dioxolane, sulfolanes, and the like can be used.

The non-aqueous organic solvent may be used alone or in admixture of one or more. If the non-aqueous organic solvent is used in combination, the mixing ratio may be appropriately adjusted according to the desired cell performance. .

In the case of the carbonate-based solvent, it is preferable to use a mixture of a cyclic carbonate and a chain carbonate. In this case, when the cyclic carbonate and the chain carbonate are mixed in a volume ratio of 1: 1 to 1: 9, the performance of the electrolytic solution may be excellent.

The non-aqueous organic solvent according to an embodiment of the present invention may further include an aromatic hydrocarbon-based organic solvent in the carbonate-based solvent. In this case, the carbonate-based solvent and the aromatic hydrocarbon-based organic solvent may be mixed in a volume ratio of 1: 1 to 30: 1.

The aromatic hydrocarbon-based organic solvent may be an aromatic hydrocarbon-based compound represented by the following formula (1).

[Chemical Formula 1]

(Wherein R ₁ to R ₆ are each a hydrogen, a halogen, a C ₁ to C 10 alkyl group, a haloalkyl group or a combination thereof)

The aromatic hydrocarbon-based organic solvent is selected from the group consisting of benzene, fluorobenzene, 1,2-difluorobenzene, 1,3-difluorobenzene, 1,4-difluorobenzene, 1,2,3- , 1,2,4-trifluorobenzene, chlorobenzene, 1,2-dichlorobenzene, 1,3-dichlorobenzene, 1,4-dichlorobenzene, 1,2,3-trichlorobenzene, 4-trichlorobenzene, iodobenzene, 1,2-diiodobenzene, 1,3-diiodobenzene, 1,4-diiodobenzene, 1,2,3-triiodobenzene, 1,2,4 - triiodobenzene, toluene, fluorotoluene, 1,2-difluorotoluene, 1,3-difluorotoluene, 1,4-difluorotoluene, 1,2,3-trifluorotoluene, 1,2,4-trifluorotoluene, chlorotoluene, 1,2-dichlorotoluene, 1,3-dichlorotoluene, 1,4-dichlorotoluene, 1,2,3-trichlorotoluene, 1,2,4 - trichlorotoluene, iodotoluene, 1,2-diiodotoluene, 1,3-diiodotoluene, 1,4-diiodotol Yen, it is 1,2,3-tree-iodo toluene, 1,2,4-iodo toluene, xylene, and selected from the group consisting of.

The non-aqueous electrolyte may further include vinylene carbonate or an ethylene carbonate-based compound represented by the following formula (2) to improve battery life.

(2)

(The [formula 2], R ₇ and R ₈ are each hydrogen, a halogen group, a cyano group (CN), nitro group (NO ₂₎ or a C1 to a to C5 fluoroalkyl group, at least one of the R ₇ and R ₈ Is a halogen group, a cyano group (CN), a nitro group (NO ₂ ) or a C1 to C5 fluoroalkyl group.

Representative examples of the ethylene carbonate-based compound include diethylene carbonate, diethylene carbonate, dibromoethylene carbonate, nitroethylene carbonate, cyanoethylene carbonate, fluoroethylene carbonate, and the like, such as difluoroethylene carbonate, chloroethylene carbonate, dichloroethylene carbonate, . When such a life improving additive is further used, its amount can be appropriately adjusted.

The lithium salt is dissolved in an organic solvent to act as a source of lithium ions in the cell to enable operation of a basic lithium secondary battery and to promote the movement of lithium ions between the anode and the cathode. The lithium salt Representative examples are _{LiPF 6, LiBF 4, LiSbF 6} , LiAsF 6, LiC 4 F 9 SO 3, LiClO 4, LiAlO 2, LiAlCl 4, LiN (C x F 2x + 1 SO 2) (C y F 2y ₊₁ SO ₂₎ (where, x and y are natural numbers), LiCl, LiI, and _{LiB (C 2 O 4) 2} ( lithium bis oxalate reyito borate (lithium bis (oxalato) borate; LiBOB) is selected from the group consisting of The concentration of the lithium salt is preferably in the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity Can exhibit excellent electrolyte performance, and lithium ions can effectively migrate.

Depending on the type of the lithium secondary battery, a separator may exist between the positive electrode and the negative electrode. The separator may be a polyethylene / polypropylene double layer separator, a polyethylene / polypropylene / polyethylene triple layer separator, a polypropylene / polyethylene / poly It is needless to say that a mixed multilayer film such as a propylene three-layer separator and the like can be used.

The lithium secondary battery can be classified into a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the type of the separator and electrolyte used. The lithium secondary battery can be classified into a cylindrical shape, a square shape, a coin shape, Depending on the size, it can be divided into bulk type and thin type. The structure and the manufacturing method of these batteries are well known in the art, and a detailed description thereof will be omitted.

FIG. 1 schematically shows a representative structure of the lithium secondary battery of the present invention. 1, the lithium secondary battery 1 includes an anode 3, a cathode 2, and an electrolyte impregnated in the separator 4 existing between the anode 3 and the cathode 2 , And a sealing member (6) for sealing the battery container (5).

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

Example

Example  One

The lithium source was charged into the mixer at a ratio (Li / Metal = 1.07) at which the amount of the lithium source was 1.07 mol per mol of the NCM complex transition metal hydroxide (molar ratio Ni: Co: Mn = 60:20:20) and the transition metal hydroxide, . Then, the dry mixed powder was heat-treated at 890 캜 for 8 hours to prepare a lithium composite compound.

Example  2

A cathode active material was prepared in the same manner as in Example 1, except that the ratio of lithium source to lithium source was 1.05 mol (Li / Metal = 1.05) relative to 1 mol of transition metal hydroxide.

Comparative Example  One

The lithium source was charged into the mixer at a ratio (Li / Metal = 1.03) of the NCM complex transition metal hydroxide (molar ratio Ni: Co: Mn = 60:20:20) and 1.0 mol of the lithium source relative to 1 mol of the transition metal hydroxide, . Then, the dry mixed powder was heat-treated at 890 캜 for 8 hours to prepare a lithium composite compound.

Coin cell  Produce

(Solvent) N-methyl-2-pyrrolidone (NMP) was added to 95% by weight of the positive electrode active material prepared in the above Examples and Comparative Examples, 2.5% by weight of carbon black as a conductive agent and 2.5% ) To 5.0 wt% to prepare a positive electrode slurry.

The positive electrode slurry was coated on an aluminum (Al) thin film as a positive electrode current collector having a thickness of 20 to 40 mu m, followed by vacuum drying and roll pressing to produce a positive electrode.

Li-metal was used as the cathode.

A coin-cell type half-cell was fabricated by using the thus prepared positive electrode and Li-metal as a counter electrode and using 1.15M LiPF6EC: DMC (1: 1 vol%) as an electrolyte solution.

Experimental Example

Experimental Example  1: Evaluation of battery characteristics

Table 1 below shows initial formations and rate characteristic data at 25 DEG C and 4.3 V in the above Examples and Comparative Examples.

Formation
Discharge capacity (mAh / g) efficiency 2.0C
Discharge capacity 2.0C
efficiency 3.0 C
Discharge capacity 3.0 C
efficiency 4.0C
Discharge capacity 4.0C
efficiency Example 1 178.27 89.34 163.41 94.12 154.82 86.59 130.29 71.66 Example 2 179.42 89.91 163.68 94.72 155.32 85.93 128.85 68.91 Comparative Example 1 179.19 89.41 162.29 92.92 149.94 74.19 113.15 62.88

As can be seen from the above Table 1, Examples 1 and 2 show characteristics of a high-output battery excellent in efficiency characteristics as compared with Comparative Example 1. [

More specifically, it is possible to control the crystal lattice to obtain better efficiency characteristics at a higher rate than the cathode active material that does not control the crystal lattice.

Experimental Example  2: X-ray diffraction  analysis

The crystal structures of Examples 1 and 2 and Comparative Example 1 were analyzed by the Rietveld method when the space group R-3m through X-ray diffraction analysis was used in the crystal structure model. The results are shown in Table 2. It is confirmed that the thickness of the MO slab is larger and the thickness of the inter slab is smaller than that of the comparative example 1, and that the degree of cation mixing is 1.5% or less.

inter slab MO slab inter slab / MO slab cation mixing Example 1 2.62478 2.11156 1.243 1.30% Example 2 2.62947 2.10762 1.248 1.50% Comparative Example 1 2.63481 2.10422 1.252 2%

Experimental Example  3: 7 Li MAS NMR  analysis

Example 1 and Comparative Example 1 were subjected to 7Li MAS NMR analysis. The analysis was performed at NMR frequency: 194.2676 MHz, Delay time: 10 sec, Number of scan: 400, π / 2 pulse: 9 μs, Reference: LiCl = 0 ppm. The results are shown in FIGS. 2 and 3. Unlike the comparative example, it can be confirmed that the impurity peak does not appear in the examples.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. As will be understood by those skilled in the art. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive.

1: lithium secondary battery 2: negative electrode
3: anode 4: separator
5: Battery container 6: Sealing member

Claims (13)

In the crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium,
Based on the X-ray diffraction analysis of the crystal lattice structure of a compound capable of reversible intercalation and deintercalation of lithium which does not control the crystal lattice by controlling the crystal lattice, the space group R-3m is subjected to a crystal structure model The thickness of the MO slab is large and the thickness of the inter slab is small due to the crystal structure analysis by the Rietveld method when used.
The method according to claim 1,
Wherein an inter slab / MO slab ratio between the MO slab and the inter slab is 1.25 or less.
The method according to claim 1,
And the thickness of the MO slab is 2.105 to 2.205.
The method according to claim 1,
Wherein the inter slab has a thickness of 2.624 to 2.634.
The method according to claim 1,
The compound capable of reversible intercalation and deintercalation of lithium controlled by the crystal lattice can be obtained by the Rietveld method when the space group R-3m is used in the crystal structure model based on the X-ray diffraction analysis, Wherein the cation mixing degree is 1.5% or less from the crystal structure analysis by the lithium secondary battery.
The method according to claim 1,
Wherein the crystal lattice-controlled compound capable of reversible intercalation and deintercalation of lithium has no impurity peak in the 7Li MAS NMR analysis.
The method according to claim 1,
The compound is represented by Li _a A _{1 - b} X _b D ₂ (0.90? A? 1.8, _{0 ? B?} 0.5), Li _a A _{1 - b} X _b O _{2 - c} T _c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05), LiE 1 - b X b O 2 - c D c _{(0≤b≤0.5, 0≤c≤0.05), LiE 2} -b X b O 4-c T c (0≤b≤0.5, 0≤c≤0.05), Li a Ni 1 -b- c Co b X _c D _α (0.90 ≦ a ≦ 1.8, 0 ≦ _b ≦ 0.5, 0 ≦ _c ≦ 0.05, 0 ≦ a ≦ 2), Li _a Ni _{1 -b c} Co _b X _c O _{2 -α} T _α ? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni _{1 -b- c} Co _b X _c O _{2 - ?} T ₂ (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni ₁ -bc Mn _b X _c D _? (0.90 _{? A?} 1.8, , 0? C? 0.05, 0??? 2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T _? (0.90 _{? A?} 1.8, 0 _? B _? 0.5, , 0 & lt _{;? &Lt}; 2), Li _a Ni _{1 -b- c} Mn _b X _c O _{2 - ?} T ₂ (0.90? A? 1.8, 0? B? 0.5, 0? C? 0.05, 0 <? <2), Li _a Ni _b e _c G _d O _{2 - e} T _e (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1 , 0≤e≤0.05), Li a Ni b Co c Mn d G e O 2 - f T f (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5 , 0.001≤e≤0.1, 0≤f≤0.05), Li a NiG b O 2 - c T c (0.90 ≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a CoG b O 2 - c T c (0.90≤a≤ 1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a _{MnG b O 2 - c T c} (0.90≤a≤1.8, 0.001≤b≤0.1, 0≤c≤0.05), Li a Mn 2 G b O 2 -c T c (0.90≤a≤1.8, 0.001≤b ? 0.1, 0? C? 0.05), Li _a MnG _b PO ₄ (0.90? A? 1.8, 0.001? B? 0.1), LiNiVO ₄ , and Li _(3-f) J ₂ (PO ₄ ) ₃ (0? F? ₂ ).
Wherein A is at least one element selected from the group consisting of Ni, Co, Mn or a combination thereof and X is at least one element selected from the group consisting of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, , S, P or a combination thereof, E is Co, Mn or a combination thereof, T is F, S, P or a combination thereof, G is a combination of Al, Cr, Mn, Fe, Mg, La , Ce, Sr, V, or combinations thereof, and J is V, Cr, Mn, Co, Ni, Cu, or combinations thereof.
The method according to claim 1,
Wherein the compound capable of reversible intercalation and deintercalation of lithium is a lithium nickel cobalt manganese composite oxide.
The method according to claim 1,
Wherein the lithium nickel cobalt manganese composite oxide is represented by the following formula (1).
[Chemical Formula 1]
Li [Li _z A _(1-za) D _a ] E _b O _{2 -b}
And in formula 1 A = Ni _α Co _β Mn _γ, D is one or more elements selected from the group consisting of Mg, Al, Zr, B and Ti, E is one member selected from the group consisting of P, F and S 0.10? Z? 0.1, 0? A? 0.05, and 0? B? 0.05, and 0.48??? 0.81, 0.09?? 0.29, and 0.09?? 0.32.
A step of dry-mixing the lithium-supplying material and the transition metal precursor, and firing the mixture to form a lithium composite compound;
Wherein the positive electrode active material is a positive electrode active material.
11. The method of claim 10,
In the step of firing the mixture to form a lithium composite compound,
And the firing temperature is 700 to 1,050 占 폚.
11. The method of claim 10,
Wherein the lithium supplying material is Li2CO3, LiOH, Li2O, Li2O2.
A positive electrode comprising the positive electrode active material for a lithium secondary battery according to any one of claims 1 to 9;
A negative electrode comprising a negative electrode active material; And
Electrolyte
And a lithium secondary battery.

Images