KR101675110B1 - Composite positive active material, positive electrode including the same, and lithium battery including the positive electrode - Google Patents

Abstract

A first metal oxide having a layered structure; And a second metal oxide having a spinel phase structure, wherein the first metal oxide and the second metal oxide form a composite body, a positive electrode including the composite positive electrode active material, and a lithium battery employing the positive electrode.

Description

[0001] The present invention relates to a composite positive electrode active material, a positive electrode including the same, and a lithium battery including the positive active material, a positive electrode including the same,

A composite cathode active material, a positive electrode containing the same, and a lithium battery.

Studies have been actively conducted to improve the capacity of these lithium batteries while using lithium batteries as driving power sources for automobiles as well as portable electronic devices. In addition, as various devices become more complex and highly functional, the lithium battery used as an energy source of a device is increasingly required to have a higher voltage in addition to downsizing and weight reduction.

In order to realize a lithium battery complying with such necessity, a cathode active material having excellent lifetime characteristics and capacity characteristics and at the same time reducing voltage characteristics is required as charging and discharging are repeated.

One aspect is to provide a structurally stable cathode active material upon charge and discharge.

Another aspect is to provide a positive electrode comprising the complex cathode active material.

Another aspect is to provide a lithium battery including the above-described anode.

A first metal oxide having a layered structure along one side; And

There is provided a composite cathode active material having a spinel phase structure and containing a second metal oxide represented by the following general formula (1), wherein the first metal oxide and the second metal oxide form a complex.

[Chemical Formula 1]

Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈

1 < a < 1 in Formula 1,

M 'is at least one selected from Group 4 to Group 10 elements, Group 13 and Group 14 elements, and manganese (Mn) is excluded.

Another aspect is to provide a positive electrode comprising the complex cathode active material.

Another aspect is to provide a lithium battery including the above-described anode.

The composite cathode active material according to one embodiment improves structural stability at high voltage charging. When a positive electrode containing such a composite cathode active material is employed, it is possible to manufacture a lithium battery having excellent lifetime characteristics and reduced voltage reduction phenomenon when charge and discharge are repeatedly performed.

1 is an exploded perspective view of a lithium battery according to one embodiment.
FIGS. 2 to 4 are X-ray diffraction (XRD) analysis graphs of the composite cathode active materials of Production Examples 1-2 and 7-8 and the composite cathode active material of Comparative Production Example 1. FIG.
5A is an X-ray diffraction analysis graph of the composite cathode active material according to Production Example 3 and Production Example 7 and the composite cathode active material according to Comparative Preparation Example 1. FIG.
FIG. 5B is an enlarged view of a partial area of FIG. 5A.
Figure 5c spinel domain size (domain size) of the contents of Li ₂ CiMn ₃ O ₈ in the composite anode active material and Li ₂ CoMn ₃ O ₈ in Comparative Preparation Example 1, a composite positive electrode active material of Preparation Example 3 and Production Example 3, and Layer domain size change.
6A to 6F show charge / discharge profiles of the lithium battery manufactured according to Examples 1-3, Examples 7 and 8 and the lithium battery manufactured according to Comparative Example 1. FIG.
FIG. 7 is a graph showing the results of a cycle life and a voltage drop analysis in a lithium battery manufactured according to Examples 2, 3 and 7 and Comparative Example 1. FIG.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view of a composite cathode active material according to an embodiment of the present invention; FIG.

A first metal oxide having a layered structure; And a second metal oxide having a spinel phase structure and represented by the following general formula (1), wherein the first metal oxide and the second metal oxide form a complex.

[Chemical Formula 1]

Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈

1 < a < 1 in Formula 1,

M 'is at least one selected from Group 4 to Group 10 elements, Group 13 and Group 14 elements, and manganese (Mn) is excluded.

In the above formula (1), Mn is excluded from M ', for example, in the group consisting of V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, One or more metals selected.

The first metal oxide having the layered structure is at least one selected from the group consisting of a compound represented by the following formula (2) and a compound represented by the following formula (3).

(2)

xLi ₂ MO ₃ .yLiMeO ₂

 Wherein M and Me are independently at least one selected from the group consisting of 4 to 10, 13, and 14 elements, x + y = 1, 0 <x <1, 0 <y <1,

(3)

_{Li a Ni x Co y Mn z} M c O 2 - e M 'e

0 <x <1, 0 <b <1, 0 <c <1, 0 <x + y + z + c <1, 0? E <1, M is at least one selected from the elements of Groups 4 to 14, and M 'is an anion element of F, S, Cl, Br or a combination thereof.

In Formula 3, M is at least one element selected from the group consisting of Ga, Si, W, Mo, Cr, Cu, Zn, Ti, , Aluminum (Al) and boron (B).

The first metal oxide having the layered structure described above may include a plurality of crystal phases having different compositions. The plurality of crystalline phases can form a complex.

The first metal oxide may include a crystal phase belonging to the C2 / m space group and a crystal phase belonging to the R-3m space group. Here, the crystal phase belonging to the C2 / m space group is Li ₂ MO ₃ , and the layered crystal phase belonging to the R-3 m space group is LiMeO ₂ .

According to one embodiment, the second metal oxide may be intermixed in the layered crystal phase in the layered structure of the first metal oxide.

The composite according to one embodiment is a composite cathode active material represented by the following formula (4).

[Chemical Formula 4]

xLi ₂ MO ₃ .yLiMeO ₂ .z Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈

1, 0 <z <1, and 1 <a <1, and M, Me and M 'are independently selected from the group consisting of 4 Group to group 10, group 13, and group 14 elements, with the proviso that M &apos; and M are different.

The composite cathode active material has a structure in which Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈ having _a spinel structure is introduced into a composite of Li ₂ MO ₃ and LiMeO ₂ having a layered structure.

₂ LiMeO lithium transition metal oxide of a layered structure has a densest crystal structure by forming an ion-binding crystal structure. Oxygen ions having the largest ionic radius form a dense layer, and lithium ions and transition metal ions are arranged in the vacancies between the oxygen ions to increase the packing density of the lithium transition metal oxide. At this time, the transition metal oxide layer composed of the transition metal and oxygen and the oxygen octahedral layer surrounding the lithium ion are alternately arranged. The inside of the MeO ₂ layer forms a strong ionic bond, and MeO ₂ layer and MeO ₂ Because of the repulsive force of the Coulomb between the layers, lithium ion can intercalate / deintercalate, and lithium ion diffuses along the two-dimensional plane, resulting in high ion conductivity.

However, when lithium is released during the charging process, MeO ₂ When the crystal expands in the c-axis direction due to the repulsive force between the oxygen atoms in the layer or when the lithium completely escapes, it shrinks rapidly in the c-axis direction, and various phase changes may be caused.

On the other hand, the Li ₂ MO ₃ .LiMeO ₂ composite is a material attracting attention as a high capacity cathode active material. However, this material forms a uLi ₂ MnO ₃ (1-u) MO ₂ (0 <u <1) structure by the deintercalation of lithium from LiMeO _{2 up} to 4.4 V at the initial charge, with _{2 O (u-δ) Li} 2 MnO 3 · δMnO 2 · (1-u) MO 2 (0 <u <1, 0 <δ <1, u + δ = 1) are formed of different. That is, at least 4.4V is formed at the same time as the desorption of lithium Li ₂ O by the generation of oxygen in the Li ₂ MnO _3, is also accompanied also generate MnO _2. These processes can be represented by the following equation (1).

[Reaction Scheme 1]

Li ₂ MnO ₃ ? VLi ₂ O + vMnO ₂ + (1-v) Li ₂ MnO ₃

In the above reaction formula 1, 0 < v < 1.

As shown in Reaction Scheme 1, Li ₂ MnO ₃ has a phase transition at the time of initial charging unlike general layered LiMO ₂ . At this time, residual Li ₂ MnO ₃ amount is determined according to the cut-off voltage of the charge. Therefore, when the end voltage is increased for the high capacity use, the residual amount of Li ₂ MnO ₃ decreases. That is, when the cadence voltage is increased, the residual amount of Li ₂ MnO ₃ that stabilizes the structure decreases, and the Li ₂ MO ₃ .LiMeO ₂ composite becomes structurally unstable.

The discharge reaction, which is the reverse reaction of the reaction shown in Reaction Scheme 1, can be represented by the following Reaction Scheme 2.

[Reaction Scheme 2]

Li + MnO ₂ → LiMnO ₂

As for the initial charge-discharge reaction, it can be seen that two molar equivalents of lithium are removed from the molar equivalent of manganese at the time of charging, and one molar equivalent of lithium is returned at the time of discharging. Due to such characteristics, the charging / discharging efficiency is low and the life characteristic of the battery may deteriorate due to the phase transition. Therefore, a cathode active material composite capable of having a stable structure even under a high voltage is required.

Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈ (for example, Li ₂ CoMn ₃ O ₈ ) constituting the formula 4 in the composite cathode active material according to one embodiment is a cubic system spinel Structure. Transition metal ions in the layered and spinel cathode materials all occupy the octahedral sites. Layered structure, to achieve a six MO ₆ are six MO ₆ are arranged in three dimensions around a single MO _6. In the other hand, the spinel structure arranged in a two-dimensional manner around a MO _6, which in the transition metal ion Due to the difference in oxidation number. The spinel compound structure is three-dimensionally connected with the octahedral planes sharing the surface to provide a path for lithium ion migration during the charging and discharging process. Li ₂ CoMn ₃ O ₈ is rich in manganese deposits, low in cost, low in toxicity, retains MnO ₂ even when lithium is all reduced (ie, in a charged state), has little heat generation and is smaller than LiMO ₂ , Good cycle performance. However, the density is low and the capacity is decreased according to the temperature.

The composite cathode active material exhibits a layered structure similar to that of two components Li ₂ MO ₃ and LiMeO ₂ upon employment, and an excess lithium is substituted in the transition metal layer. In order to be applied as a high capacity anode, a cathode active material in which lithium is present in the transition metal layer within about 20% should be used. However, such a cathode active material has a minimum of 4.5 V

etc. The structural stability of the cathode active material at high voltage is important because it is a system capable of obtaining a high capacity by charging at least Li / Li +. For example, in the case of charging at about 4.4 V or more, Li ₂ MnO ₃ is accompanied by generation of oxygen and generation of MnO ₂ at the same time as lithium is desorbed. At this time, the higher the charge voltage, since the remaining amount of Li ₂ MnO ₃ based on the terminal voltage reduces the amount of Li ₂ MnO ₃ is decreased structural stability of the positive electrode active material.

However, the composite anode active material is _{Li 2 M '(1 + a} ) Mn (3-a) , such as having a spinel Li ₂ CoMn ₃ O ₈ in order to improve the phenomenon of reducing the structural integrity described above represented by the formula (4) O ₈ is introduced into a composite of a layered structure of Li ₂ MnO ₃ and LiMO ₂ , thereby improving the stability of the anode structure and improving the lifetime characteristics and voltage characteristics at high voltage charging.

In Formula 4, M and Me are independently selected from the group consisting of Mn, vanadium, Cr, Fe, Co, Ni, Zr, Selected from the group consisting of Al, Al, Boron, Ge, Ru, Sn, Ti, Nb, Mo and Pt. Wherein M 'is at least one metal selected from the group consisting of V, Cr, Fe, Co, Ni, Zr, Re, Al, B, Ge, Ru, Sn, Ti, Nb, It is one or more metals. However, M and M 'are differently selected.

The M 'may be Co, for example.

When Co is introduced as M 'of Li ₂ M' _{(1 + a)} Mn _(3-a) O ₈ , a new intermediate band is formed between the existing band gaps and the band gap energy is reduced, 1 &lt; / RTI &gt; metal oxide can be improved. In addition, the composite cathode active material into which Co is introduced has a high voltage stability as well as preventing a decrease in discharge capacity by suppressing the dissolution of manganese of the first metal oxide in the electrolyte and suppressing Jahn Teller distortion.

When a charge / discharge test is performed for a positive electrode containing a composite cathode active material according to one embodiment and a half-cell using a lithium metal as a counter metal, the average discharge voltage in the 50th cycle is calculated based on the average discharge voltage in the first cycle To 97.95%. Thus, it can be confirmed that the mean discharge voltage decay is decreased in the composite cathode active material of Formula 4.

According to one embodiment, 0 <x? 0.6, 0 <y? 0.5, 0 <z? 0.05,

-0.5? A? 0.5. When a charge / discharge test was conducted for a cathode including a composite cathode active material having such a composition and a lithium metal as a counter metal, the average discharge voltage in the 50th cycle was 97.5 To 99.95%. When the composite cathode active material having the above composition is used, the effect of reducing the average discharge voltage of the lithium battery is greater.

According to one embodiment, M is manganese (Mn), M 'is iron (Fe), iron

Is at least one metal selected from the group consisting of Co, Ni, Ru, Zr and Ti.

In the above formula (4), z is 0.005 to 0.1, for example 0.005, 0.025, 0.01, 0.05, 0.075 or 0.1.

In Formula 4, Me may be a composite cathode active material represented by Formula 5 below.

[Chemical Formula 5]

Ni _1-bc Co _b Mn _c

In the formula (5), 0 <b <0.5, 0.2 <c <0.5 and b + c = 1.

Composite positive electrode active material represented by the formula (5), for example, _{Ni 0 .4 Co 0 .2 Mn 0} .4, Ni 0.5 Co 0.2 Mn 0.3, Ni 0 .6 Co 0 .2 Mn 0 .2 or Ni _1/3 a _{Co 1/3 Mn 1/3} . And _{Li 2 M '(1 + a} ) Mn (3-a) O 8 , for example, _{Li 2 Co (1 + a)} Mn (3-a) O 8, Li 2 Ni (1 + a) Mn (3 _-a) O ₈ , Li ₂ Fe _{(1 + a)} Mn _(3-a) O ₈ , or Li ₂ Ti _{(1 + a)} Mn _(3-a) O ₈ .

The _{Li 2 M '(1 + a} ) Mn (3-a) O 8 is specifically _{Li 2 Co 1 .5 Mn 2 .5} O 8, Li 2 CoMn 3 O 8, Li 2 Ni 1 .5 Mn 2. _{5 O 8, Li 2 NiMn 3} O 8, Li 2 Fe 1 .5 Mn 2 .5 O 8, Li 2 FeMn 3 O 8, Li 2 TiMn 3 O 8, or _{Li 2 Ti 1 .5 Mn 2 .5} O ₈ .

The complex cathode active material represented by Formula 4 may be, for example, a compound represented by Formula 6 below

[Chemical Formula 6]

_{xLi 2 MnO 3 · yLiNi 1 -b-} c Co b Mn c O 2 · z Li 2 M '(1 + a) Mn (3-a) O 8

M 'in Formula 6 is at least one selected from the group consisting of Fe, Co, Ni and Ti, 0 <b <0.5, 0.2 <c <0.5, b + c = 1,

0 <x? 0.6, 0 <y? 0.5, 0 <z? 0.1, and -0.5? A?

In Formula _{6 LiNi 1 -b- c Co b Mn} c O 2 , for example, _{LiNi 0 .4 Co 0 .2 Mn 0} .4 O 2, LiNi 0.5 Co 0.2 Mn 0.3 O 2, or Is _{LiNi 1/3 Co 1/3} Mn 1/3 O 2.

According to one embodiment, the complex represented by the formula (4) includes, for example, a compound represented by the following formula (7).

(7)

xLi ₂ MnO ₃ .yLi Ni _b Co _d Mn _e O ₂ .z Li ₂ Co _{(1 + a)} Mn _(3-a) O ₈

0 <b <1, 0 <e <1, b + d + e = 1 and 0 <x? 0.6, 0 <y? 0.5, 0 <z? 0? A? 0.5.

The complex represented by Formula 4 may be, for example, 0.545 Li ₂ MnO ₃ .045 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ 0.005 Li ₂ CoMn ₃ O ₈ ; _{0.525Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.025 Li 2 CoMn 3 O 8; _{0.50Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.05Li 2 CoMn 3 O 8; _{0.54Li 2 MnO 3 · 0.45LiNi 0.4 Co} 0.2 Mn 0.4 O 2 · 0.01Li 2 Co 1 .5 Mn 2 .5 O 8; _{0.525Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.025Li 2 Co 1.5 Mn 2.5 O 8; _{0.50Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.05Li 2 Co 1 .5 Mn 2 .5 O 8; _{0.45Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.1Li 2 CoMn 3 O 8; _{0.45Li 2 MnO 3 · 0.45LiNi 0.4 Co} 0.2 Mn 0.4 O 2 · 0.1Li 2 Co 1 .5 Mn 2 .5 O 8; _{0.475Li 2 MnO 3 · 0.45LiNi 0 .4} Co 0 .2 Mn 0 .4 O 2 · 0.075 Li 2 CoMn 3 O 8; Or 0.475Li a _{2 MnO 3 · 0.45LiNi 0 .4 Co} 0 .2 Mn 0 .4 O 2 · 0.075Li 2 Co 1 .5 Mn 2 .5 O 8.

The composition of the composite cathode active material according to one embodiment can be confirmed by X-ray diffraction analysis.

In the composite cathode active material of Formula 4 according to one embodiment, a diffraction peak appears at a 2θ value of 36 to 37 ° in an X-ray diffraction measurement using a Cu-kα line.

Among LiMeO ₂ to the diffraction peak A is the value that appears at 2θ 36.85 ° to 36.95 constitutes a layered structure (e.g. (311) plane of Li ₂ Co _{(1 + a)} Mn _(3-a) O ₈ having a spinel structure, and the diffraction peak B at 2θ values of 36.43 to 36.50 degrees for the (101) plane of LiNiCoMnO ₂ Lt; / RTI &gt; The LiMeO ₂ constituting the layered structure in the composite cathode active material through the intensity ratio of the diffraction peak (for example, LiNiCoMnO ₂ ) and Li ₂ Co _{(1 + a)} Mn _(3-a) O ₈ having a spinel structure can be confirmed.

The half width at the diffraction peak B is 0.070 to 0.075 degrees, for example 0.07026 to 0.07344 degrees. And the half width at the diffraction peak A is 0.09 to 0.13 deg., For example, 0.09033 to 0.1224 deg.

The domain size (hereinafter referred to as a spinel phase domain size) of Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈ having the spinel phase structure described above is larger than the domain size of the layered structure. For example, the spinel phase domain size is 2.0 to 2.4 nm, for example, 2.210 to 2.310 nm. The domain size of LiMeO ₂ having a layered structure (hereinafter referred to as layered domain size) is 1.3 to 1.8 nm, for example, 1.328 to 1.799 nm.

The domain size of the Li ₂ MO ₃ .LiMeO ₂ structure having the layered structure is less than 2.0 nm.

The spinel phase domain size and the stratified domain size described above have peaks for the (311) plane of Li ₂ Co _{(1 + a)} Mn _(3-a) O ₈ having a spinel phase structure and LiMeO ₂ (FWHM) of the peak with respect to the (101) plane. This method will be described in more detail. The domain size La can be obtained from the half-width value of the diffraction peak using the Scherrer equation of the following equation (1).

[Formula 1]

La = (0.9?) / (? Cos?)

In Equation (1),? Is the X-ray wavelength (1.54 Å, and? Is the full width at half maximum ( FWHM) at the Bragg angle.

The composite cathode active material may have an average particle diameter of 10 nm to 500 μm, or 20 nm to 100 μm, or 1 μm to 30 μm. A lithium battery having improved physical properties can be provided when the average particle diameter of the composite cathode active material is in the above range.

Composite anode active material according to one embodiment is the tap density is from 0.5 to 3g / cm ^3. By using the composite cathode active material having such a tap density, a lithium battery improved in voltage and lifetime characteristics can be obtained.

A coating film may be formed on the surface of the composite cathode active material. If a coating film is further formed as described above, the use of a cathode containing such a composite cathode active material can improve charge / discharge characteristics, lifetime characteristics, and high-voltage characteristics.

According to one embodiment, the coating layer may include at least one selected from a conductive material, a metal oxide, and an inorganic fluoride.

The conductive material is at least one selected from a carbon-based material, a conductive polymer, ITO, RuO ₂ , and ZnO.

The carbon-based material may be crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in the form of amorphous, plate-like, flake, spherical or fibrous type, and the amorphous carbon may be soft carbon or hard carbon carbon fiber, carbon fiber, mesophase pitch carbide, fired cokes, graphene, carbon black, fullerene soot, carbon nanotubes, and carbon fiber, and the like, Anything that can be used is possible.

Examples of the carbon-based material include carbon nanotubes, fullerene, graphene, and carbon fibers. Examples of the conductive polymer include polyaniline, polythiophene, polypyrrole, and mixtures thereof.

Examples of the metal oxide include at least one selected from the group consisting of silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), and mixtures thereof.

The inorganic fluoride _{AlF 3, CsF, KF, LiF} , NaF, RbF, TiF, AgF, AgF₂, BaF 2, CaF 2, CuF 2, CdF 2, FeF 2, HgF 2, Hg 2 F 2, MnF 2, MgF _{2, NiF 2, PbF 2,} SnF 2, SrF 2, XeF 2, ZnF 2, AlF 3, BF 3, BiF 3, CeF 3, CrF 3, DyF 3, EuF 3, GaF 3, GdF 3, Fe F3, _{HoF 3, InF 3, LaF 3} , LuF 3, MnF 3, NdF 3, VOF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3, YbF 3, TIF 3 _{, CeF4, GeF 4, HfF 4} , SiF 4, SnF 4, TiF 4, VF 4, ZrF 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF 6, ReF 6, SF 6 and WF ₆ &Lt; / RTI &gt;

According to one embodiment, the coating film may comprise an oxide of a coating element, a hydroxide, an oxyhydroxide of a coating element, an oxycarbonate of a coating element, or a coating element compound of a hydroxycarbonate of a coating element. The compound constituting these coating layers may be amorphous or crystalline. As coating elements contained in the coating layer, at least one of Sc, Y, Nb, Cr, Mo, W, Mn, Fe, B, In, C, Sb, La, Ce, Sm, Gd, Mg, , Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr or a mixture thereof. The coating film forming process may be any coating method as long as it can coat the above compound by a method that does not adversely affect physical properties of the cathode active material (for example, spray coating, dipping, etc.) by using these elements, It will be omitted because it is well understandable to those engaged in the field.

According to one embodiment, the coating film may have a continuous film form or may have a discontinuous film, for example an island form.

Hereinafter, a method of manufacturing the composite cathode active material according to one embodiment will be described.

The method for producing the composite cathode active material is not particularly limited, but for example, a co-precipitation method, a solid phase method, and the like can be used.

First, the coprecipitation method will be described. A composite cathode active material having a uniform composition can be obtained.

A metal hydroxide represented by the following general formula (8a), a metal carbonate represented by the general formula (8b), a metal oxalate represented by the general formula (8c) or (8d) is mixed with a lithium compound and the mixture is heated in an air or oxygen atmosphere at 400 to 1200 ° C To obtain a composite cathode active material represented by the following formula (4).

[Chemical Formula 8a]

Me (OH) ₂

In Formula (8a), Me is at least one selected from the group consisting of Group 4 to Group 10 elements.

[Formula 8b]

MeCO ₃

In the above formula (8b), Me is at least one selected from the group 4 to group 10 elements.

[Chemical Formula 8c]

MeOC (= O) C (= O) O

[Chemical Formula 8d]

Me (C ₂ O ₄ )

In the above formulas (8c) and (8d), Me is at least one selected from the group 4 to group 10 elements.

[Chemical Formula 4]

xLi ₂ MO ₃ .yLiMeO ₂ .z Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈

Z <1, 0 <x <1, 0 <y <1, 0 <z <

M, Me and M 'are, independently from each other, at least one member selected from the group consisting of 4 to 10, 13 and 14 elements,

Except that M &apos; and M are selected differently.

Examples of the lithium compound include lithium carbonate (Li ₂ CO ₃ ), lithium sulfate (Li ₂ SO 4), lithium nitrate (LiNO ₃ ), lithium hydroxide (LiOH) and the like. Here, the lithium compound is stoichiometrically mixed with the metal compound represented by the general formulas (8a) to (8d) so as to obtain the composition of the composite cathode active material represented by the general formula (4).

The heat treatment is carried out at 400 to 1200 DEG C, for example, 900 DEG C under air or oxygen atmosphere. The heat treatment time is variable depending on the heat treatment temperature, but is performed in the range of, for example, 5 minutes to 20 hours.

The precursor mixture may be obtained by mixing the M precursor, the M precursor, the Me precursor, the Mn precursor, and the solvent in the compounds represented by Formulas 8a through 8d. Here, water, an alcohol-based solvent and the like are used as the solvent. As the alcoholic solvent, ethanol or the like is used.

The content of the solvent is 200 to 3000 parts by weight based on 100 parts by weight of the total amount of the M precursor, M 'precursor, Me precursor and Mn precursor. When the content of the solvent is within the above range, a mixture in which the precursors are uniformly mixed can be obtained. The mixing is carried out at, for example, 20 to 80 캜, for example, 60 캜.

M precursors include M carbonate, M sulfate, M age cateate, M chloride, and the like. And the M 'precursor, the Mn precursor and the Me precursor are the same as the M precursor except that M', Mn and Me are included instead of M, respectively.

The M precursor may be, for example, a manganese precursor. Specifically, the manganese precursor uses manganese sulfate, manganese nitrate, manganese chloride, and the like. The M 'precursor may be a cobalt precursor. Cobalt precursors include, for example, cobalt sulfate, cobalt nitrate, and cobalt chloride.

Me precursors include, for example, manganese precursors, nickel precursors and cobalt precursors. The manganese precursor and the cobalt precursor are as described above, and the nickel precursor is nickel sulfate, nickel nitrate, nickel chloride, and the like.

Adding a chelating agent and a pH adjusting agent to the precursor mixture to perform a coprecipitation reaction to obtain a precipitate. The precipitate thus obtained is filtered and heat-treated. The heat treatment is carried out at 20 to 110 캜, for example, at 80 캜. When the heat treatment temperature is in the above range, the reactivity of the coprecipitation reaction is excellent.

The chelating agent controls the rate of formation of the precipitate in the coprecipitation reaction, and includes ammonium hydroxide (NH ₄ OH), citric acid, and the like. The chelating agent content is used at a conventional level.

If sodium hydroxide is used as the pH adjusting agent (precipitant), the metal hydroxide represented by the above formula (8a) is obtained. When sodium carbonate is used as the pH adjusting agent, the metal carbonate represented by the above formula (8b) is obtained. When sodium oxalate is used as the pH adjusting agent, the metal oxalate represented by the general formula (8d) is obtained.

The pH adjusting agent serves to adjust the pH of the reaction mixture to 6 to 12, and examples thereof include ammonium hydroxide, sodium hydroxide (NaOH), sodium carbonate (Na ₂ CO ₃ ), sodium oxalate (Na ₂ C ₂ O ₄ ) do.

The metal compound may be represented by, for example, the following formula (8e).

[Chemical Formula 8e]

Ni _{1 -b- d} Co _b Mn _c X

In the formula 8e, 0 <b <0.5, 0.2 <c <0.5, b + c = 1, and X is -OH, -CO ₃ , or -C ₂ O ₄ .

The metal compounds include, for example, and the like _{Ni 0 .4 Co 0 .2 Mn 0} .4 (OH) 2.

Hereinafter, a method for producing the composite cathode active material according to the solid phase method is as follows.

M, M 'and Mn precursors are mixed to obtain a precursor mixture.

The mixing can be carried out mechanically using, for example, a ball mill, a bamboo mixer, a homogenizer, or the like. Zirconia balls can be used for mechanical mixing.

The mechanical mixing treatment time is variable, but is carried out for, for example, 20 minutes to 10 hours, for example, 30 minutes to 3 hours.

In the mechanical mixing, an alcohol solvent such as ethanol may be added to increase the mixing efficiency.

The content of the solvent is 100 to 3000 parts by weight based on 100 parts by weight of the total content of the M precursor, M 'precursor, Me precursor and Mn precursor. When the content of the solvent is in the above range, a mixture in which the precursor is dissolved evenly can be obtained.

The M precursors are, for example, M hydroxides, M oxides, or M carbonates. The M 'precursor and the Mn precursor are the same except that M' and Mn are used instead of M in the M precursor respectively.

The precursor mixture is then heat treated at 400 to 1200 ° C. Drying is accomplished through this heat treatment process.

The resultant product is mixed with a lithium compound and then heat-treated to obtain a composite cathode active material represented by the general formula (4). Here, the lithium compound may be the same as the compound described in the coprecipitation method described above. And the composition of the lithium compound is controlled so as to obtain the composite cathode active material of Chemical Formula (4).

The heat treatment is performed at 400 to 1200 ° C, for example, at 650 to 900 ° C under air or oxygen atmosphere.

The heat treatment time varies depending on the heat treatment temperature, but is performed for 3 to 20 hours.

The composite cathode active material according to one embodiment can be manufactured by a common manufacturing method such as spray pyrolysis in addition to the co-precipitation method and the solid phase method.

According to another aspect, there is provided a positive electrode comprising the aforementioned composite positive electrode active material.

According to another aspect, there is provided a lithium battery including the positive electrode.

The anode is prepared according to the following method.

A cathode active material composition in which a cathode active material, a binder and a solvent are mixed is prepared.

A conductive agent may further be added to the cathode active material composition.

The positive electrode active material composition is directly coated on the metal current collector and dried to produce a positive electrode plate. Alternatively, the cathode active material composition may be cast on a separate support, and then the film peeled from the support may be laminated on the metal current collector to produce a cathode plate.

The electrochemical active material composite according to one embodiment may be used as the positive electrode active material.

The electrochemical active material composite may further include a first cathode active material which is a cathode active material conventionally used in a lithium battery.

The first cathode active material may further include at least one selected from the group consisting of lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide, but is not limited thereto Any cathode active material available in the art may be used.

For example, Li _a A _{1 - b} B _b D ₂ , where 0.90? A? 1.8, and 0? B? 0.5; Li _a E _{1 -b} B _b O _{2 -c} D _c wherein, in the formula, 0.90? A? 1.8, 0? B? 0.5, 0 _{? C?} 0.05; LiE _{2 - b} B _b O _{4 - c} D _{c where} 0? B? 0.5, 0 _{? C?} 0.05; Li _a Ni _{1 -b- c} Co _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Co _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c D _? Wherein, in the formula, 0.90 _{? A?} 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _{1 -b- c} Mn _b B _c O _{2 - ?} F _? Wherein? 0.90? A? 1.8, 0 _? B _? 0.5, 0 _? C _? 0.05, 0 <? Li _a Ni _b E _c G _d O ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0.001? D? 0.1; Li _a Ni _b Co _c Mn _d GeO ₂ wherein 0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, 0? D? 0.5, and 0.001? E? 0.1. Li _a NiG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a CoG _b O ₂ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); Li _a MnG _b O ₂ (in the above formula, 0.90? A? 1.8, and 0.001? B? 0.1); Li _a Mn ₂ G _b O ₄ (in the above formula, 0.90? A? 1.8, 0.001? B? 0.1); QO _2; QS ₂ ; LiQS ₂ ; V ₂ O ₅ ; LiV ₂ O ₅ ; LiIO ₂ ; LiNiVO _4; Li _(3-f) J ₂ (PO ₄ ) ₃ (0 _{? F? 2} ); _{(0≤f≤2) Li (3-f} ) Fe 2 (PO 4) 3; A compound represented by any one of the formulas of LiFePO ₄ can be used.

In the above formula, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or combinations thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

The cathode active material may be, for example, a compound represented by the following formula (9), a compound represented by the following formula (10) or a compound represented by the following formula (11).

[Chemical Formula 9]

Li _a Ni _b Co _c Mn _d O ₂

0.90? A? 1.8, 0? B? 0.9, 0? C? 0.5, and 0? D? 0.9.

[Chemical formula 10]

Li ₂ MnO ₃

(11)

LiMO ₂

In the above formula (11), M is Mn, Fe, Co, or Ni.

Examples of the conductive agent include carbon black, graphite fine particle natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fiber; Metal powders or metal fibers or metal tubes such as carbon nanotubes, copper, nickel, aluminum, and silver; Conductive polymers such as polyphenylene derivatives, and the like, but not limited thereto, and any conductive polymer may be used as long as it can be used as a conductive agent in the art.

Examples of the binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyimide, polyethylene, polyester, polyacrylonitrile, polymethylmethacrylate, polytetrafluoroethylene (PTFE) Carboxymethylcellulose-styrene

 Butadiene rubber (SMC / SBR) copolymer, styrene-butadiene rubber-based polymer, or a mixture thereof.

As the solvent, N-methylpyrrolidone, acetone or water may be used.

But not limited to, all of those which can be used in the technical field.

The content of the composite cathode active material, the conductive agent, the binder, and the solvent is a level commonly used in a lithium battery. At least one of the conductive agent, the binder and the solvent may be omitted depending on the use and configuration of the lithium battery.

The negative electrode can be obtained by carrying out almost the same method except that the negative electrode active material is used instead of the positive electrode active material in the positive electrode manufacturing process described above.

As the negative electrode active material, a carbon-based material, silicon, a silicon oxide, a silicon-based alloy, a silicon-carbon-based material composite, a tin, a tin alloy, a tin-carbon composite or a metal oxide or a combination thereof is used.

The carbon-based material may be crystalline carbon, amorphous carbon or a mixture thereof. The crystalline carbon may be graphite such as natural graphite or artificial graphite in the form of amorphous, plate-like, flake, spherical or fibrous type, and the amorphous carbon may be soft carbon or hard carbon carbon fiber, carbon fiber, mesophase pitch carbide, fired cokes, graphene, carbon black, fullerene soot, carbon nanotubes, and carbon fiber, and the like, Anything that can be used is possible.

The negative electrode active material may be selected from the group consisting of Si, SiOx (0 <x <2, for example, 0.5 to 1.5), Sn, SnO ₂ or a silicon-containing metal alloy and mixtures thereof. At least one of Al, Sn, Ag, Fe, Bi, Mg, Zn, In, Ge, Pb and Ti may be used as the metal for forming the silicon alloy.

The negative electrode active material may include a metal / metalloid alloy that is alloyable with lithium, an alloy thereof, or an oxide thereof. For example, the metal / metalloid capable of being alloyed with lithium may be at least one selected from the group consisting of Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (Y is an alkali metal, an alkali earth metal, (Y is an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element, a transition metal, a rare earth element, or a combination element thereof, and is a transition metal, a rare earth element or a combination element thereof and not Si) , Sn), MnOx (0 < x? 2), and the like. 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, or a combination thereof. For example, the oxide of the metal / metalloid capable of alloying with lithium may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, SnO ₂ , SiO _x (0 <x <2) and the like.

For example, the negative electrode active material may include one or more elements selected from the group consisting of Group 13 elements, Group 14 elements, and Group 15 elements of the Periodic Table of the Elements.

For example, the negative electrode active material may include at least one element selected from the group consisting of Si, Ge, and Sn.

The content of the negative electrode active material, the conductive agent, the binder and the solvent is a level commonly used in a lithium battery.

The separator is interposed between the anode and the cathode, and an insulating thin film having high ion permeability and mechanical strength is used.

The pore diameter of the separator is generally 0.01 to 10 mu m, and the thickness is generally 5 to 20 mu m. Examples of the periferator include an olefin-based polymer such as polypropylene; A sheet or nonwoven fabric made of glass fiber, polyethylene or the like is used. When a solid polymer electrolyte is used as the electrolyte, the solid polymer electrolyte may also serve as a separator.

Of the separators, polyethylene, polypropylene, polyvinylidene fluoride or a multilayer film of two or more thereof may be used. Specific examples of the olefin-based polymer include polyethylene / polypropylene two-layer separator, polyethylene / polypropylene / polyethylene A three-layer separator, a polypropylene / polyethylene / polypropylene three-layer separator, and the like can be used.

The lithium salt-containing nonaqueous electrolyte is composed of a nonaqueous electrolyte and a lithium salt.

As the non-aqueous electrolyte, a non-aqueous electrolyte, an organic solid electrolyte, or an inorganic solid electrolyte is used.

The nonaqueous electrolytic solution includes an organic oil. These organic solvents may be used as long as they can be used as organic solvents in the art. Examples of the solvent include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate N, N-dimethylformamide, N, N-dimethylformamide, tetrahydrofuran, tetrahydrofuran, Dimethylacetamide, N, N-dimethylsulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether or mixtures thereof.

Examples of the organic solid electrolyte include a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, a polyelectrolytic lysine, a polyester sulfide, a polyvinyl alcohol, a polyvinylidene chloride, And the like can be used.

Examples of the inorganic solid electrolyte include Li ₃ N, LiI, Li ₅ NI ₂ , Li ₃ N-LiI-LiOH, Li ₂ SiS ₃ , Li ₄ SiO ₄ , Li ₄ SiO ₄ -LiI- ₃ PO ₄ -Li ₂ S-SiS _2, and the like can be used.

The lithium salt is a material that is readily soluble in the non-aqueous electrolyte, for _{example, LiPF 6, LiBF 4, LiSbF} 6, LiAsF 6, LiClO 4, LiCF 3 SO 3, Li (CF 3 SO 2) 2 N, LiC ₄ F ₉ SO ₃ , 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, . For the purpose of improving the charge-discharge characteristics and the flame retardancy, non-aqueous electrolytes include, for example, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylenediamine, glyme, hexamethylphosphoamide hexamethyl phosphoramide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N, N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, Etc. may be added. In some cases, a halogen-containing solvent such as carbon tetrachloride or ethylene trifluoride may be further added to impart nonflammability.

As shown in FIG. 1, the lithium battery 11 includes an anode 13, a cathode 12, and a separator 34. The positive electrode 13, the negative electrode 12 and the separator 14 described above are wound or folded and accommodated in the battery case 15. Then, the organic electrolyte is injected into the battery case 15 and the cap assembly 16 is sealed to complete the lithium battery 11. The battery case may have a cylindrical shape, a rectangular shape, a thin film shape, or the like. For example, the lithium battery may be a thin film battery. The lithium battery may be a lithium ion battery.

A separator may be disposed between the anode and the cathode to form a battery structure. The cell structure is laminated in a bi-cell structure, then impregnated with an organic electrolyte solution, and the obtained result is received in a pouch and sealed to complete a lithium ion polymer battery.

In addition, a plurality of battery assemblies may be stacked to form a battery pack, and such battery pack may be used for all devices requiring high capacity and high output. For example, a notebook, a smart phone, an electric vehicle, and the like.

A positive electrode containing a positive electrode active material containing a composite positive electrode active material according to one embodiment,

When the voltage (V, abscissa) with respect to the lithium metal and the charge / discharge capacity are differentiated by the above voltage (dQ / dV, vertical axis) in the charge / discharge test result of the half cell using lithium metal as the counter metal, Shows a redox peak existing in the spinel structure in the 2.0 to 3.0 V interval with respect to the lithium metal at the time of charge / discharge of the complex.

The lithium battery according to one embodiment is suitable for an electric vehicle (EV) because it has a high rate characteristic and a good life characteristic. For example, a hybrid vehicle such as a plug-in hybrid electric vehicle (PHEV).

Will be explained in more detail through the following examples and comparative examples. However, the embodiments are for illustrative purposes only and are not intended to be limiting.

Comparative Manufacturing Example  1: Preparation of composite cathode active material

Were synthesized by the coprecipitation method described below.

Composite positive electrode using nickel sulfate, cobalt sulfate and manganese sulfate as the starting material in the active material _{(0.55Li 2 MnO 3 0.45LiNi 0.} 4 Co 0 .2 Mn 0 .4 O 2) is so as to obtain the starting material with a stoichiometric .

Nickel sulfate, cobalt sulfate and manganese sulfate were dissolved in distilled water at a concentration of 2M to obtain a precursor mixture. NH ₄ OH as a chelating agent and NaOH as a precipitant were added to this precursor mixture and a coprecipitation reaction was carried out at 60 ° C. for 4 hours to obtain a precipitate (Ni, Co, Mn) (OH) ₂ .

The precipitate (Ni, Co, Mn) (OH) ₂ obtained by the above procedure was washed with distilled water and dried at 80 ° C for 24 hours, and then mixed with lithium carbonate. Here, the lithium carbonate is a composite positive electrode active material _{(0.55Li 2 MnO 3 · 0.45LiNi 0} . 4 Co 0.2 Mn 0.4 O 2) so as to obtain a mixed stoichiometrically.

The mixture of the composite anode active material was heat-treated at 900 ℃ 10 sigan target under an air atmosphere 0.55Li ₂ MnO ₃ · 0.45LiNi _{0. 4 Co 0 .2 Mn 0 .4 O} 2 was obtained.

Comparative Manufacturing Example  2: Preparation of a mixture of cathode active material

The comparison produced 0.55Li ₂ MnO ₃ obtained according to example _{1 · 0.45LiNi 0 .4 Co 0 .2} Mn 0 .4 O 2 and Li ₂ O ₃ CoMn ₈ to 97.5: 2.5 were mixed at a molar ratio of 0.55Li ₂ MnO ₃ · _{0.45LiNi 0 .4 Co 0 .2 Mn 0} .4 O 2 and Li ₂ to give a mixture of the CoMn ₃ O _8.

Comparative Manufacturing Example  3: Preparation of composite cathode active material

(0.55 Li ₂ MnO ₃ .0.40 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ - Ni) was performed in the same manner as in Comparative Example 1, except that nickel sulfate, cobalt sulfate, and manganese sulfate were selected to have a stoichiometric composition. 0.05 LiMn ₂ O ₄ ).

Manufacturing example  1: Preparation of composite cathode active material

(0.545Li ₂ MnO ₃ .045 LiNi _{0) was} obtained in the same manner as in Comparative Preparation Example 1, except that nickel sulfate, cobalt sulfate and manganese sulfate were selected in a composition that Li ₂ CoMn ₃ O ₈ was 0.5 mol% _0.4 was prepared _{Co 0 .2 Mn 0 .4 O 2} · 0.005Li 2 CoMn 3 O 8).

Manufacturing example  2: Preparation of composite cathode active material

Except that nickel sulfate, cobalt sulfate, and manganese sulfate were selected as the composition in which Li ₂ CoMn ₃ O ₈ was _2.5 mol%, and a composite cathode active material (0.525 Li ₂ MnO ₃ .0.45 Li ₂ Ni _0.4 Co _0.2 Mn _0.4 O ₂ 0.025 Li ₂ CoMn ₃ O ₈ ).

Manufacturing example  3: Preparation of composite cathode active material

(0.50Li ₂ MnO ₃ .0.45 Li ₂ Ni _0.4 Co _0.2 Mn (Mn ₂ O ₃₎₎ was prepared in the same manner as in Production Example 1, except that nickel sulfate, cobalt sulfate and manganese sulfate were selected in a composition that Li ₂ CoMn ₃ O ₈ was 5 mol% _0.4 O ₂ 0.05 Li ₂ CoMn ₃ O ₈ ).

Manufacturing example  4: Preparation of composite cathode active material

Li ₂ Co _{1 .5} Mn _{2 .5} O ₈ is 1 mol%, nickel sulfate, cobalt sulfate, and manganese sulfate

Composite positive electrode active material and by the same manner as in Preparation Example 1 except that the low-priced _{(0.54Li 2 MnO 3 · 0.45LiNi 0} .4 Co 0 .2 Mn 0 .4 O 2 · 0.01Li 2 Co 1 .5 Mn 2 .5 O ₈ ).

Manufacturing example  5: Preparation of composite cathode active material

_{Li 2 Co 1 .5 Mn 2 .5} O 8 is in and is carried out in the same manner as in Preparation Example 1, except that selection of nickel sulfate, cobalt sulfate, manganese sulfate in the composition is 2.5mol% composite positive electrode active material (0.525Li ₂ MnO _{3 · 0.45LiNi 0.4 Co 0.2 Mn 0.4 O} 2 · 0.0025Li 2 Co 1 .5 was prepared Mn _{2 .5} O _8).

Manufacturing example  6: Preparation of composite cathode active material

_{Li 2 Co 1 .5 Mn 2 .5} O 8 is in the proportion of sulfuric acid is 5mol% nickel, cobalt sulfate, and the composite positive electrode active material by the same manner as in Preparation Example 1, except that the selection of manganese sulfate (0.50Li ₂ MnO _{3 · 0.45LiNi 0.4 Co 0.2 Mn 0.4 O} 2 · 0.05Li 2 Co 1 .5 was prepared Mn _{2 .5} O _8).

Manufacturing example  7: Preparation of composite cathode active material

(0.45Li ₂ MnO ₃ .0.45LiNi _0.4 Co _0.2 (0.45 Li ₂ MnO ₃ .0) was prepared in the same manner as in Production Example 1, except that nickel sulfate, cobalt sulfate and manganese sulfate were selected in a composition that Li ₂ CoMn ₃ O ₈ was 10 mol% Mn _0.4 O ₂ 0.1 Li ₂ CoMn ₃ O ₈ ).

Manufacturing example  8: Preparation of composite cathode active material

(0.475Li ₂ MnO ₃ .0.45 Li ₂ Ni _0.4 Co _0.2 (0.5 mol%) was prepared in the same manner as in Production Example 1, except that nickel sulfate, cobalt sulfate and manganese sulfate were selected in a composition that Li ₂ CoMn ₃ O ₈ was 7.5 mol% Mn _0.4 O ₂ 0.075 Li ₂ CoMn ₃ O ₈ ).

Manufacturing example  9: Preparation of composite cathode active material

_{Li 2 Co 1 .5 Mn 2 .5} O 8 is in the proportion of sulfuric acid to be 10mol% nickel, cobalt sulfate, and is a composite positive electrode active material by the same procedure as in Preparation Example 4, except that the selection of manganese sulfate (0.45Li ₂ MnO _{3 · 0.45LiNi 0.4 Co 0.2 Mn 0.4 O} 2 · 0.1Li 2 Co 1 .5 was prepared Mn _{2 .5} O _8).

Manufacturing example  10: Preparation of composite cathode active material

_{Li 2 Co 1 .5 Mn 2 .5} O 8 is 7.5mol, and the composite positive electrode active material by the same manner as in Preparation Example 4, except that selection of nickel sulfate, cobalt sulfate, manganese sulfate in the composition are% (0.475Li ₂ MnO _{3 · 0.45LiNi 0.4 Co 0.2 Mn 0.4 O} 2 · 0.075Li 2 Co 1 .5 was prepared Mn _{2 .5} O _8).

Comparative Example  One

A slurry was prepared by mixing a composite cathode active material, a carbon conductive agent (Denka Black) and a binder PVDF in an NMP solvent at a weight ratio of 90: 5: 5 according to Comparative Preparation Example 1.

The prepared slurry was coated on an Al substrate (thickness: 15 탆) using a doctor blade, dried at 120 캜 under reduced pressure, and rolled by a roll press to form an electrochemical cell.

In the cell manufacturing process, metal lithium was used as a counter electrode and an electrolyte obtained by dissolving 1.3M LiPF 6 in a mixed solvent (EC: EMC: DEC = 3: 5: 2 by volume) was used as an electrolyte.

Comparative Example  2

An electrochemical cell was fabricated in the same manner as in Comparative Example 1 except that the composite cathode active material obtained in Comparative Preparation Example 2 was used in place of the composite cathode active material according to Comparative Preparation Example 1.

Comparative Example  3

An electrochemical cell was fabricated in the same manner as in Comparative Example 1, except that the cathode active material mixture was used in place of the composite cathode active material according to Comparative Preparation Example 3, in place of the composite cathode active material.

Example  1-10

An electrochemical cell was fabricated in the same manner as in Comparative Example 1, except that the composite cathode active material obtained in Production Example 1-10 was used instead of the composite cathode active material in Comparative Production Example 1, respectively.

Evaluation example  1: X-ray diffraction  analysis

1) The composite cathode active material of Production Examples 1-2 and 7-8 and the composite cathode active material of Comparative Production Example 1, the composite cathode active material of Production Examples 1-2 and 7-8, and the lithium composite oxide of Comparative Production Example 1 Was subjected to X-ray diffraction analysis using CuKα.

The X-ray diffraction analysis was performed using a Rigaku RINT2200HF + diffractometer using Cu Kradiation (1.540598 Å).

The X-ray analysis results are shown in Figs. 2 to 4. FIGS. 2 to 4 show the composite cathode active material of Production Example 2-3 and Production Example 7-8 and the composite cathode active material of Comparative Production Example 1, respectively. FIG. 3 and FIG. 4 respectively show Li ₂ CoMn ₃ O ₈ and (311) and (222) regions of Li ₂ CoMn ₃ O ₈ .

Case 2 to Li ₂ CoM _n3 O ₈ 10.0 mole% of 4 Preparation Example 7, Li ₂ when CoM _n3 O is ₈ is 7.5 mol% of the preparation 8, Li ₂ CoM _n3 O _8, 5.0% mol in cases when the preparation 3, Li ₂ O ₈ CoM _n3 of 2.5 mol%, if Production example 2, Li ₂ O ₈ CoM _n3 is 0 mol% is for the Comparative Production example 1.

The composite cathode active material of Production Example 2-3 and Production Example 7-8 is different from the composite cathode active material of Comparative Production Example 1 in Li ₂ CoMn ₃ O ₈ Phase, and it was confirmed that the composite cathode active material had a Li ₂ MnO ₃ -LiNiCoMnO ₂ -Li ₂ CoMn ₃ O ₈ phase. The mixing ratio of Li ₂ MnO ₃ and Li ₂ CoMn ₃ O ₈ was found through the intensity ratio of the diffraction peak appearing at 2θ values of 18.5 to 19.5 ° and the diffraction peak appearing at 21 to 23 ° of 2θ values, The diffraction peak appearing at 36 to 37 ° appeared as a peak corresponding to the (311) plane of Li ₂ CoMn ₃ O _{8 at} a position different from that of the conventional spinel phase.

2) The composite cathode active material of Production Example 3 and Production Example 7, the composite cathode active material of Comparative Production Example 1 and Li ₂ CoMn ₃ O ₈

X-ray diffraction analysis of the composite cathode active material of Production Example 3 and Production Example 7 and the composite cathode active material of Comparative Production Example 1 and Li ₂ CoMn ₃ O ₈ using CuKα was performed.

The X-ray diffraction analysis was performed using a Rigaku RINT2200HF + diffractometer using Cu Kradiation (1.540598 Å).

The X-ray analysis results are shown in Figs. 5A to 5C. 5B is an enlarged view of the case where 2? Is in a range of 30 to 40 DEG in FIG. 5A.

(Hereinafter referred to as diffraction peak B) of Li ₂ CoMn ₃ O ₈ having a spinel structure in FIG. 5A and a diffraction peak (hereinafter referred to as diffraction peak B) of LiNiCoMnO ₂ having a layered structure with respect to the (101) A), and the spinel phase domain size and the stratified domain size were calculated, respectively, and the results are shown in Table 1 below. The change in the spinel phase domain size and the layered domain size according to the content of Li ₂ CoMn ₃ O ₈ in the above Table 1 is shown in FIG.

division rescue
(Diffraction peak) 2? (?) FWHM (°) Domain size (nm) 0 mol% Li ₂ CoMn ₃ O ₈
(Li ₂ MnO ₃ -LiNiCoMnO ₂ )
(Comparative Production Example 1) Stratified
(Diffraction peak A) 36.87125 0.09033 1.799 Spinel phase
(Diffraction peak B) - - - 5 mol% Li ₂ CoMn ₃ O ₈
(Production Example 3) Stratified
(Diffraction peak A) 36.90926 0.09033 1.799 Spinel phase
(Diffraction peak B) 36.45173 0.07026 2.310 10 mol% Li ₂ CoMn ₃ O ₈
(Production Example 7) Stratified
(Diffraction peak A) 36.89431 0.1224 1.328 Spinel phase
(Diffraction peak B) 36.43668 0.07344 2.210 Li ₂ CoMn ₃ O ₈ Stratified
(Diffraction peak A) - - - Spinel phase
(Diffraction peak B) 36.34444 0.08568 1.894

From Table 1 and FIG. 5c, it can be seen that the spinel phase domain size decreases as the spinel phase content increases.

Evaluation example  2: Charging and discharging  characteristic

The lithium batteries produced in Example 1-8 and Comparative Examples 1 and 3 were subjected to first and second charge-discharge and cycle charge-discharge at 25 ° C.

The batteries prepared according to Example 1-8 and Comparative Example 1-3 were each charged with 0.1 C to 4.7 V CC and then discharged at a constant current of 0.1 C up to 2.5 V.

From the second charge, 2.5V 0.2C / 1C / 2C discharge was performed after charging to 0.05C current after charging 4.6V CC / CV 0.5C. The cycle was evaluated by charging 2.5 V 1C 50 times after charging 4.6V CC 1C.

The above-described cycle was repeated 50 times.

The initial efficiency, the rate performance, the discharge voltage drop, and the capacity retention rate are expressed by the following formulas 2 to 5. The initial discharge capacity is the discharge capacity in the first cycle.

[Formula 2]

Initial efficiency = {(primary cycle discharge capacity) / (primary cycle charge capacity)} x 100

[Formula 3]

Rate capability = {(2C discharge capacity) / (0.2C discharge capacity)} x 100

[Formula 4]

Discharge voltage drop [mV] = [average discharge voltage in 50 th cycle - average discharge voltage in 1st cycle]

The average discharge voltage is a discharge voltage corresponding to an intermediate value of the discharge capacity in each cycle.

[Formula 5]

Capacity retention rate [%] = [Discharge capacity at 50th cycle / Discharge capacity at 1st cycle] × 100

The initial efficiency and the rate-limiting performance obtained as a result of evaluating the charge-discharge characteristics of the lithium battery produced in Example 1-8 are shown in Table 2 below.

division
Primary cycle Rate performance 0.1C charge capacity
(mAh / g) 0.1C discharge capacity
(mAh / g) Initial efficiency (%) 2C / 0.2C (%) Example 1 352 268 76.2 70.5 Example 2 332 281 84.5 71.4 Example 3 307 249 81.0 74.5 Example 4 341 277 81.1 68.3 Example 5 337 287 85.1 61.8 Example 6 317 264 83.1 76.0 Example 7 237 178 75.0 - Example 8 271 206 76.1 -

From Table 2, it can be seen that the lithium battery produced according to Example 1-8 has excellent initial efficiency and rate-limiting performance.

The charge / discharge characteristics of the lithium battery prepared in Examples 9 and 10 were evaluated, and the results were almost the same as those in Example 1-8.

Table 3 shows the capacity retention rate and the discharge voltage drop among the charge / discharge characteristics evaluation results of the lithium battery manufactured according to Example 1-6 and Comparative Examples 1 and 3. Here, the discharge voltage drop refers to the difference between the discharge voltage in the 50th cycle and the discharge voltage in the one cycle

division Average voltage (V)
Discharge voltage
descent
(?) (MV) 50 cycles
Average voltage / cycle average voltage (%) Life (50th)
(%) One cycle 50 cycles Example 1 3.453 3.417 -36 98.95 83.8 Example 2 3.443 3.386 -57 98.96 85.8 Example 3 3.452 3.397 -55 98.34 83.4 Example 4 3.442 3.383 -59 98.29 83.9 Example 5 3.443 3.380 -63 97.67 83.6 Example 6 3.489 3.424 -65 99.85 84.8 Comparative Example 1 3.457 3.388 -69 - - Comparative Example 3 - - -67 - 83.3

With reference to Table 3 above, the lithium battery of Example 1-6 is superior in life characteristics, and has a voltage drop due to introduction of Li ₂ CoMn ₃ O ₈ , which is a spinel phase, as compared with the lithium battery obtained according to Comparative Examples 1 and 3 The phenomenon was improved.

Charging and discharging  profile

The charging / discharging profile of the lithium battery manufactured according to Examples 1-3, 7-8, and Comparative Example 1 was examined and shown in FIGS. 6A to 6F.

Charging and discharging conditions were about 0.1C constant current charging to about 4.7V during charging, and discharge was discharged to about 2.5V at a constant current of 0.1C.

The lithium battery produced according to Examples 1-3 and 7-8 exhibited a large initial capacity and reduced capacity reduction with increasing cycle as compared with Comparative Example 1, It was confirmed that a uniform profile appears without voltage drop. Activation of Li ₂ MnO ₃ was observed at about 4.5 V plateau. In the charge / discharge cycle, voltage flattening is observed at about 2.7 V compared to the lithium metal, so that the spinel phase can be seen.

FIG. 7 shows the differential charge / discharge curve in the first cycle of the lithium battery produced according to Examples 2, 3 and 7 and Comparative Example 1. FIG.

As shown in FIG. 7, according to Examples 2, 3 and 7, unlike Comparative Example 1, there was an oxidative reduction peak in the 2.5 to 2.7 V section.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. It will be apparent to those skilled in the art that various modifications and variations are possible in light of the above teachings will be. Accordingly, the scope of protection of the present invention should be determined by the appended claims.

11: Lithium battery 12: cathode
13: anode 14: separator
15: battery case 16: cap assembly

Claims (30)

A first metal oxide having a layered structure; And
1. A composite cathode active material having a spinel phase structure and comprising a second metal oxide represented by the following general formula (1), wherein the first metal oxide and the second metal oxide form a complex, and the complex is a compound represented by the following general formula (4)
[Chemical Formula 1]
Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈
1 < a < 1 in Formula 1,
M 'is at least one member selected from Group 4 to Group 10 elements, Group 13 and Group 14 elements, except for manganese (Mn)
[Chemical Formula 4]
xLi ₂ MO ₃ .yLiMeO ₂ .z Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈
X + y + z = 1, 0 <x <1, 0 <y <1, 0.005 z <0.05, -1 <a <1,
M is at least one element selected from the group consisting of manganese (Mn), vanadium (V), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), zirconium (Zr), rhenium (Re) At least one metal selected from the group consisting of germanium (Ge), ruthenium (Ru), tin (Sn), titanium (Ti), niobium (Nb), molybdenum (Mo)
M 'is at least one selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni) and titanium (Ti)
Me is at least one element selected from the group consisting of Mn, vanadium, chromium, iron, cobalt, nickel, zirconium, rhenium, aluminum, At least one metal selected from the group consisting of germanium (Ge), ruthenium (Ru), tin (Sn), titanium (Ti), niobium (Nb), molybdenum (Mo) and platinum (Pt) delete The method according to claim 1,
Wherein the first metal oxide having the layered structure comprises a plurality of crystal phases having different compositions. The method according to claim 1,
A second metal oxide in the layered structure of the first metal oxide
A composite cathode active material that is intermixed. delete The method according to claim 1,
In Formula 4 xLi ₂ MO ₃ · yLiMeO ₂ has a layered structure,
In formula (4), zLi ₂ M ' _{(1 + a)} Mn _(3-a) O ₈ has a spinel phase structure. delete The method according to claim 1,
When the charge / discharge test is performed on the positive electrode comprising the complex cathode active material and the lithium metal as the counter metal, the average discharge voltage in the 50th cycle is 97.5 to 99.95 based on the average discharge voltage in the first cycle. % Composite cathode active material. The method according to claim 1,
0? X? 0.6, 0? Y? 0.5, 0.005? Z? 0.05, and -0.5? A? 0.5 in the general formula (4). 10. The method of claim 9,
When the charge / discharge test is performed on the positive electrode comprising the complex cathode active material and the lithium metal as the counter metal, the average discharge voltage in the 50th cycle is 97.5 to 99.95 based on the average discharge voltage in the first cycle. % Composite cathode active material. The method according to claim 1,
In Formula 4, M is manganese (Mn). delete delete The method according to claim 1,
In Formula 4, Me is a composite cathode active material represented by the following Formula 5:
[Chemical Formula 5]
Ni _1-bc Co _b Mn _c
In the formula (5), 0 <b <0.5, 0.2 <c <0.5 and b + c = 1. The method according to claim 1,
The _{Li 2 M '(1 + a} ) Mn (3-a) O 8 is _{Li 2 Co (1 + a)} Mn (3-a) O 8, Li 2 Ni (1 + a) Mn (3-a) O ₈ , Li ₂ Fe _{(1 + a)} Mn _(3-a) O ₈ , or Li ₂ Ti _{(1 + a)} Mn _(3-a) O ₈ . The method according to claim 1,
The _{Li 2 M '(1 + a} ) Mn (3-a) O 8 is _{Li 2 Co 1 .5 Mn 2 .5} O 8, Li 2 CoMn 3 O 8, Li 2 Ni 1 .5 Mn 2 .5 O _{8, Li 2 NiMn 3 O 8} , Li 2 Fe 1 .5 Mn 2 .5 O 8, Li 2 FeMn 3 O 8, Li 2 TiMn 3 O 8, or _{Li 2 Ti 1 .5 Mn 2 .5} O 8 in Composite cathode active material. The method according to claim 1,
Wherein the composite cathode active material is a compound represented by Formula 6:
[Chemical Formula 6]
xLi ₂ MnO ₃ .yLi Ni _1-bc Co _b Mn _c O ₂ .z Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈
In Formula 6, M 'is at least one selected from the group consisting of Fe, Co, Ni, and Ti,
0 <b <0.5, 0.2 <c <0.5, b + c = 1, 0 <x? 0.6, 0 <y? 0.5, 0.005? Z? 0.05, and -0.5? A? The method according to claim 1,
Wherein the composite cathode active material represented by Formula 4 is a compound represented by Formula 7:
(7)
xLi ₂ MnO ₃ .yLi Ni _b Co _d Mn _e O ₂ .z Li ₂ Co _{(1 + a)} Mn _(3-a) O ₈
0 <b <1, 0 <d <1, 0 <e <1, b + d + e = 1, 0 <x? 0.6, 0? Y? 0.5, 0.005? Z? 0.05, 0? A? 0.5. The method according to claim 1,
Wherein the composite cathode active material is 0.545 Li ₂ MnO ₃ 0.45 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ 0.005 Li ₂ CoMn ₃ O ₈ ; 0.525 Li ₂ MnO ₃ 0.45 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ 0.025 Li ₂ CoMn ₃ O ₈ ; _{0.50Li 2 MnO 3 · 0.45LiNi 0.4 Co} 0.2 Mn 0.4 O 2 · 0.05 Li 2 CoMn 3 O 8; 0.54 Li ₂ MnO ₃ 0.45 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ 0.01 Li ₂ Co _1.5 Mn _2.5 O ₈ ; _{0.525Li 2 MnO 3 · 0.45LiNi 0.4 Co} 0.2 Mn 0.4 O 2 · 0.025Li 2 Co 1.5 Mn 2.5 O 8; Or 0.50 Li ₂ MnO ₃ 0.45 LiNi _0.4 Co _0.2 Mn _0.4 O ₂ 0.05 Li ₂ Co _1.5 Mn _2.5 O ₈ ; The method according to claim 1,
Wherein the domain size of the spinel phase structure is larger than the domain size of the layered structure. The method according to claim 1,
A composite cathode active material having a domain size of Li ₂ M ' _{(1 + a)} Mn _(3-a) O ₈ having a spinel phase structure of 2.0 to 2.4 nm. The method according to claim 6,
The domain size of the Li ₂ MO ₃ .LiMeO ₂ structure having the layered structure is less than 2.0 nm. The composite cathode active material The method according to claim 1,
Ray diffractometry using a Cu-k? Ray has a half width of a diffraction peak at a 2θ value of 36.43 to 36.50 ° of 0.070 to 0.075 °. The method according to claim 1,
A composite cathode active material on which a coating film containing at least one selected from the group consisting of a conductive material, a metal oxide, and an inorganic fluoride is formed on the surface of the composite cathode active material. 25. The method of claim 24,
The conductive material may be a carbon-based material, indium tin oxide (ITO, RuO ₂ And ZnO. 25. The method of claim 24,
The metal oxide is silica (SiO _2), alumina (Al ₂ O _3), zirconium oxide (ZrO _2), titanium oxide (TiO ₂₎ and a composite positive electrode active material is at least one selected from the group consisting of a mixture thereof. 25. The method of claim 24,
The inorganic fluoride _{AlF 3, CsF, KF, LiF} , NaF, RbF, TiF, AgF, AgF₂, BaF 2, CaF 2, CuF 2, CdF 2, FeF 2, HgF 2, Hg 2 F 2, MnF 2, MgF _{2, NiF 2, PbF 2,} SnF 2, SrF 2, XeF 2, ZnF 2, AlF 3, BF 3, BiF 3, CeF 3, CrF 3, DyF 3, EuF 3, GaF 3, GdF 3, Fe F3, _{HoF 3, InF 3, LaF 3} , LuF 3, MnF 3, NdF 3, VOF 3, PrF 3, SbF 3, ScF 3, SmF 3, TbF 3, TiF 3, TmF 3, YF 3, YbF 3, TIF 3 _{, CeF4, GeF 4, HfF 4} , SiF 4, SnF 4, TiF 4, VF 4, ZrF 4, NbF 5, SbF 5, TaF 5, BiF 5, MoF 6, ReF 6, SF 6 and WF ₆ And the composite cathode active material is at least one selected from the group consisting of: The method according to claim 1,
The results of charging / discharging tests of a cathode including a composite cathode active material and a lithium metal as a counter metal are shown as a voltage (V, abscissa) and a charge / discharge capacity (dQ / dV , Vertical axis), the complex cathode active material exhibits a redox peak existing in the spinel structure in a 2.0 to 3.0 V interval with respect to the lithium metal at the time of charging and discharging. An anode comprising the composite cathode active material according to any one of claims 1, 3, 4, 6, 8 to 11, 14 to 28. 29. A lithium battery employing the positive electrode according to claim 29.

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