Cathode active material and lithium secondary battery comprising same

Abstract

The present invention relates to a cathode active material, and a lithium secondary battery comprising the same, the present invention provides a cathode active material, represented by the following Chemical Formula 1, wherein I003/I104 ratio is 1.6 or more, and R-factor value represented by the following Formula 1 is 0.40 to 0.44, and c-axis lattice constant (c) and a-axis lattice constant (a) satisfy 3(a)+5.555≤(c)≤3(a)+5.580:
R-factor=(I102+I006)/(I101)  Formula 1 wherein I003, I006, I101, I102, and I104 are the intensity of diffraction peaks on the (003), (006), (101), (102), and (104) planes by X-ray diffraction analysis using CuKα-rays,
Li.sub.α[(Ni.sub.xCo.sub.y).sub.1-βA.sub.β]O.sub.z  Chemical Formula 1 in the Chemical Formula 1, 0.95≤α≤1.1, 0.75≤x≤0.95, 0.03≤y≤0.25, 0<β≤0.2, and 1.9≤z≤2.1, and A is a dopant metal element, and the average oxidation number N of A is 3.05≤N≤3.35.

Claims

1. A cathode active material, represented by the following Chemical Formula 1, wherein I003/I104 ratio is 1.6 or more, and R-factor value represented by the following Formula 1 is 0.40 to 0.44, and c-axis lattice constant (c) and a-axis lattice constant (a) satisfy 3(a)+5.555≤(c)≤3(a)+5.580:
R-factor=(I102+I006)/(I101)  Formula 1 wherein I003, I006, I101, I102, and I104 are the intensity of diffraction peaks on the (003), (006), (101), (102), and (104) planes by X-ray diffraction analysis using CuKα-rays,
Li.sub.α[(Ni.sub.xCo.sub.y).sub.1-βA.sub.β]O.sub.z  Chemical Formula 1 in the Chemical Formula 1, 0.95≤α≤1.1, 0.75≤x≤0.95, 0.03≤y≤0.25, 0<β≤0.2, and 1.9≤z≤2.1, and A is a dopant metal element, and the average oxidation number N of A is 3.05≤N≤3.35.

2. The cathode active material of claim 1, wherein 0.88≤x≤0.92, and 0.08≤y≤0.12, in the Chemical Formula 1.

3. The cathode active material of claim 1, wherein the content of the dopant A is 12,000 ppm or less on the basis of the total weight of the active material.

4. The cathode active material of claim 1, wherein the content of the dopant A is 10,000 ppm or less on the basis of the total weight of the active material.

5. The cathode active material of claim 1, wherein the formation discharge capacity at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material is 200mAh/g or more.

6. The cathode active material of claim 1, wherein when charge and discharge at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material, the discharge capacity is 180 mAh/g or more in the 50.sup.th cycle.

7. The cathode active material of claim 6, wherein when charge and discharge at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material, the 1.sup.st cycle capacity÷50.sup.th cycle capacity ratio is 95% or more.

8. The cathode active material of claim 1, wherein the grain size of the cathode active material is 500 or more and 550 or less in Angstrom units.

9. A lithium secondary battery comprising: a cathode comprising the cathode active material according to claim 1; an anode comprising an anode active material; and an electrolyte.

10. A cathode active material, represented by the following Chemical Formula 1, wherein I003/I104 ratio is 1.6 or more, and R-factor value represented by the following Formula 1 is 0.40 to 0.44, and c-axis lattice constant (c) and a-axis lattice constant (a) satisfy 3(a)+5.555≤(c)≤3(a)+5.580:
R-factor=(I102+I006)/(I101)  [Formula 1] wherein I003, I006, I101, I102, and I104 are the intensity of diffraction peaks on the (003), (006), (101), (102), and (104) planes by X-ray diffraction analysis using CuKα-rays,
Li.sub.α[(Ni.sub.xCo.sub.y).sub.1-βA.sub.β]O.sub.z  [Chemical Formula 1] in the Chemical Formula 1, 0.95≤α≤1.1, 0.75≤x≤0.95, 0.03≤y≤0.25, 0<β≤0.2, and 1.9≤z≤2.1, and A is a dopant metal element, and the average oxidation number N of A is 3.05≤N≤3.35, and Mn is excluded from A.

11. The cathode active material of claim 10, wherein 0.88≤x≤0.92, and 0.08≤y≤0.12, in the Chemical Formula 1.

12. The cathode active material of claim 10, wherein the content of the dopant A is 12,000 ppm or less on the basis of the total weight of the active material.

13. The cathode active material of claim 10, wherein the content of the dopant A is 10,000 ppm or less on the basis of the total weight of the active material.

14. The cathode active material of claim 10 wherein the formation discharge capacity at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material is 200mAh/g or more.

15. The cathode active material of claim 10, wherein when charge and discharge at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material, the discharge capacity is 180 mAh/g or more in the 50.sup.th cycle.

16. The cathode active material of claim 15, wherein when charge and discharge at (Li/Li.sup.+) 4.3V of the coin cell comprising the cathode active material, the 1.sup.st cycle capacity÷50.sup.th cycle capacity ratio is 95% or more.

17. The cathode active material of claim 10, wherein the grain size of the cathode active material is 500 or more and 550 or less in Angstrom units.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic view of a lithium secondary battery according to one embodiment of the present invention.

(2) FIG. 2 is a schematic diagram of the content range of a representative dopant.

(3) FIG. 3 shows the relationship between the oxidation number and the cycle capacity retention rate of one Example and Comparative Examples of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(4) Hereinafter, the embodiments of the present invention will be described in detail.

(5) Meanwhile, it should be understood that the embodiments described herein are merely some examples of the present invention, and accordingly, these are not intended to be limiting and to be defined only by the scope of the claims appended hereto.

(6) In another embodiment of the present invention provides a lithium secondary battery comprising a cathode, a anode and an electrolyte, wherein the cathode comprises a current collector and a cathode active material layer formed on the current collector, wherein the cathode active material layer comprises the above-mentioned cathode active material.

(7) Descriptions related to the cathode active material are omitted as same as described above.

(8) The cathode active material layer may comprise a binder and a conductive material.

(9) The binder serves to appropriately bind cathode active material particles to each other and appropriately bind the cathode active material to the current collector, and as a representative example of the binder, polyvinylalcohol, carboxymethylcellulose, hydroxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, a polymer comprising ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, an epoxy resin, nylon, or the like, may be used, but the binder is not limited thereto.

(10) The conductive material is used in order to impart conductivity to the electrode, and any material may be used as long as it does not cause chemical changes in a battery to be configured and is an electron-conductive material, and as an example, a conductive material comprising a carbon based material such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or the like; a metal based material such as metal powder or metal fiber of copper, nickel, aluminum, silver, or the like; a conductive polymer such as a polyphenylene derivative, or the like; or a mixture thereof may be used.

(11) The anode comprises a current collector and an anode active material layer formed on the current collector, and the anode active material layer comprises an anode active material.

(12) An example of the anode active material comprises a material capable of reversibly intercalating and deintercalating lithium ions, a lithium metal, a lithium metal alloy, a material capable of doping and dedoping lithium, or a transition metal oxide.

(13) As the material capable of reversibly intercalating and deintercalating lithium ions, any carbon based anode active material may be used as long as it is generally used as a carbon material in a lithium ion secondary battery, as a representative example, crystalline carbon or amorphous carbon may be used, or crystalline carbon and amorphous carbon may be used together with each other.

(14) Examples of the crystalline carbon may comprise non-shaped or sheet, flake, spherical, or fiber-shaped natural graphite or artificial graphite, and examples of the amorphous carbon may comprise soft carbon (low-temperature fired carbon), hard carbon, mesophase pitch carbide, fired cokes, and the like.

(15) As the lithium metal alloy, an alloy of lithium and a metal selected from the group consisting of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn may be used.

(16) Examples of the material capable of doping and dedoping lithium may comprise Si, SiO.sub.x (0<x<2), a Si—Y alloy (Y is an element selected from the group consisting of alkali metals, alkali earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements, and a combination thereof, but is not Si), Sn, SnO.sub.2, Sn—Y (Y is an element selected from the group consisting of alkali metals, alkali earth metals, group 13 elements, group 14 elements, transition metals, rare earth elements, and a combination thereof, but is not Sn), and the like, and further, at least one thereof may also be mixed with SiO.sub.2 and then used.

(17) The element Y may be 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, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, and a combination thereof.

(18) Examples of the transition metal oxide may comprise vanadium oxide, lithium vanadium oxide, and the like.

(19) The anode active material layer may also comprise a binder, and selectively, the anode active material layer may further comprise a conductive material.

(20) The binder serves to appropriately bind anode active material particles to each other and appropriately bind the anode active material to the current collector, and as a representative example of the binder, polyvinylalcohol, carboxymethylcellulose, hydroxypropylcellulose, polyvinylchloride, carboxylated polyvinylchloride, polyvinylfluoride, a polymer comprising ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, acrylated styrene-butadiene rubber, an epoxy resin, nylon, or the like, may be used, but the binder is not limited thereto.

(21) The conductive material is used in order to impart conductivity to the electrode, and any material may be used as long as it does not cause chemical changes in a battery to be configured and is an electron-conductive material, and as an example, a conductive material comprising a carbon based material such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, or the like; a metal based material such as metal powder or metal fiber of copper, nickel, aluminum, silver, or the like; a conductive polymer such as a polyphenylene derivative, or the like; or a mixture thereof may be used.

(22) As the current collector, a material selected from the group consisting of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and a combination thereof may be used.

(23) As a material of the current collector, Al may be used, but is not limited thereto.

(24) The anode and the cathode may be manufactured by mixing active materials, the conductive material, and the binder in a solvent to prepare active material compositions, and applying the compositions on the current collector, respectively.

(25) Since a method of manufacturing an electrode as described above is well-known in the art, a detailed description thereof will be omitted in the present specification.

(26) As the solvent, N-methylpyrrolidone, or the like, may be used, but the solvent is not limited thereto.

(27) The cathode and the anode may be separated by a separator, and as the separator, any separator may be used as long as it is commonly used in lithium batteries.

(28) In particular, it is suitable to have low resistance to ion migration of the electrolyte and excellent ability to contain the electrolyte.

(29) For example, a material selected from glass fiber, polyester, teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and combinations thereof may be in the form of a nonwoven or woven fabric.

(30) The separator has a pore diameter of 0.01 to 10 μm and of which a thickness of 5 to 300 μm may be used.

(31) The lithium salt-containing non-aqueous electrolyte consists of a non-aqueous electrolyte and lithium.

(32) As the non-aqueous electrolyte, a non-aqueous electrolyte solution, a solid electrolyte, an inorganic solid electrolyte, or the like are used.

(33) As the non-aqueous electrolyte solution, for example, aprotic organic solvents such as N-methyl-2-pyrrolidinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxy ethane, tetrahydroxy franc, 2-methyl tetrahydrofuran, dimethyl sulfoxide, 1,3-dioxolon, formamide, dimethylformamide, dioxolon, acetonitrile, nitromethane, methyl formate, methyl acetate, phosphate triester, trimethoxy methane, dioxorone derivatives, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, ethers, methyl pyroionate and ethyl propionate, or the like may be used.

(34) As the organic solid electrolyte, for example, polyethylene derivatives, polyethylene oxide derivatives, polypropylene oxide derivatives, phosphate ester polymers, poly agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, polymers comprising ionic dissociating groups, or the like may be used.

(35) As the inorganic solid electrolyte, nitride, halide, sulfate, silicate of Li, or the like can be used, for example Li.sub.3N, LiI, Li.sub.5NI.sub.2, Li.sub.3N—LiI—LiOH, LiSiO.sub.4, LiSiO.sub.4—LiI—LiOH, Li.sub.2SiS.sub.3, Li.sub.4SiO.sub.4, Li.sub.4SiO.sub.4—LiI—LiOH, Li.sub.3PO.sub.4—Li.sub.2S—SiS.sub.2, or the like.

(36) The lithium salt may be used as long as it is commonly used in lithium batteries, as a material which is good to dissolve in the non-aqueous electrolyte, for example, at least one from LiCl, LiBr, LiI, LiClO.sub.4, LiBF.sub.4, LiB.sub.10Cl.sub.10, LiPF.sub.6, LiCF.sub.3SO.sub.3, LiCF.sub.3CO.sub.2, LiAsF.sub.6, LiSbF.sub.6, LiAlCl.sub.4, CH.sub.3SO.sub.3Li, CF.sub.3SO.sub.3Li, (CF.sub.3SO.sub.2).sub.2NLi, lithium chloroborate, lower aliphatic lithium carbonate, lithium tetraphenyl boronate, imide and the like may be used.

(37) Lithium secondary batteries may be classified as a lithium ion battery, a lithium ion polymer battery, and a lithium polymer battery depending on the kinds of separator and electrolyte used therein, be classified as a cylindrical battery, a prismatic battery, a coin type battery, a pouch type battery, and the like, depending on a shape thereof, and be classified as a bulk type battery and a thin film type battery depending on a size thereof.

(38) In addition, both lithium primary batteries and lithium secondary batteries are possible.

(39) Since structures and manufacturing methods of these batteries are well-known in the art, a detailed description thereof will be omitted.

(40) FIG. 1 schematically illustrates a representative structure of a lithium secondary battery according to one embodiment of the present invention.

(41) Referring to FIG. 1, the lithium battery 30 comprises a cathode 23, an anode 22, and a separator 24 disposed between the cathode 23 and the anode 22.

(42) The cathode 23, the anode 22, and the separator 24 described above are wound or folded to be accommodated in the battery container 25.

(43) Subsequently, an electrolyte is injected into the battery container 25 and encapsulated with an encapsulation member 26 to complete the lithium battery 30.

(44) The battery container 25 may be cylindrical type, prismatic type, thin film type, or the like.

(45) The lithium battery may be a lithium ion battery.

(46) The lithium battery is suitable for the use requiring high capacity, high output, and high temperature operation, such as electric vehicles, in addition to the use of conventional mobile phones, portable computers, and the like, and it may also be used in hybrid vehicles in combination with existing internal combustion engines, fuel cells, and supercapacitors.

(47) In addition, the lithium battery may be used for all other uses requiring high output, high voltage, and high temperature operation.

(48) Hereinafter, the present invention will be described with reference to some preferred examples and comparative examples.

(49) However, the examples are described herein to illustrate certain preferred embodiments of the present invention, and the present invention is not limited thereto.

Example: Preparation of Cathode Active Material

(50) To obtain the desired cathode active materials of Examples 1 to 7, and Comparative Examples 1 to 9, Ni.sub.0.9Co.sub.0.1(OH).sub.2, which is a nickel-based metal hydroxide precursor, and LiOH, which is a lithium supply material, were dry mixed with a lab mixer.

(51) Next, according to each Examples and Comparative Examples, TiO.sub.2 which is Ti supply material and B.sub.2O.sub.3 which is B raw material, Mg(OH).sub.2 which is Mg raw material, Al(OH).sub.2 which is Al raw material, and ZrO.sub.2 which is Zr raw material were mixed uniformly dry.

(52) A total of 4.0 kg of the dry mixture is filled in a mullite saggar and fired in a box-type sintering furnace in an air atmosphere, at elevated temperature of 6.56 hr, holding 16.88 hr and cooling 6.56 hr (Total 30 hrs firing at a temperature condition of 755° C.) for a total of 30 hours.

(53) Specific dopant content of the prepared active material is shown in Table 1 below.

(54) TABLE-US-00001 TABLE 1 Doping contents (ppm, on the basis of the total weight of the active Doping ratio (ppm, on the basis of the Average material) total weight of the active material) Oxidation Al B Mg Ti Zr total Al B Mg Ti Zr total Number Comparative 0 0 0 0 0 — Example 1 Comparative 5000 5000 0.000 0.000 0.000 1.000 0.000 1.000 4.00 Example 2 Comparative 5000 5000 1.000 0.000 0.000 0.000 0.000 1.000 3.00 Example 3 Comparative 5000 0 0 500 5500 0.956 0.000 0.000 0.044 0.000 1.000 3.04 Example 4 Comparative 5000 0 2000 5000 12000 0.525 0.000 0.233 0.241 0.000 1.000 3.01 Example 5 Comparative 5000 0 3000 5000 13000 0.470 0.000 0.313 0.216 0.000 1.000 2.90 Example 6 Comparative 10000 0 500 5000 15500 0.778 0.000 0.043 0.179 0.000 1.000 3.14 Example 7 Comparative 5000 0 1000 1000 7000 0.761 0.000 0.169 0.070 0.000 1.000 2.90 Example 8 Comparative 10000 0 200 2000 12200 0.898 0.000 0.020 0.083 0.000 1.000 3.06 Example 9 Example 1 5000 0 0 2500 7500 0.813 0.000 0.000 0.187 0.000 1.000 3.19 Example 2 5000 0 0 5000 10000 0.685 0.000 0.000 0.315 0.000 1.000 3.31 Example 3 5000 0 500 5000 10500 0.637 0.000 0.071 0.293 0.000 1.000 3.22 Example 4 5000 0 1000 5000 11000 0.595 0.000 0.132 0.273 0.000 1.000 3.14 Example 5 3000 0 500 5000 8500 0.513 0.000 0.095 0.393 0.000 1.000 3.30 Example 6 8000 0 500 5000 13500 0.737 0.000 0.051 0.212 0.000 1.000 3.16 Example 7 5000 0 500 2500 2500 10500 0.672 0.000 0.075 0.154 0.099 1.000 3.18

(55) The kind and content ratio of the metal element comprised in the complex oxide are measured by ICP (high frequency inductive coupling plasma) measurement.

(56) Further, since the raw material of manufactures, input ratio thereof, and the analysis value of ICP are almost corresponded, when the composite oxide cannot be measured by ICP, the kind and content ratio of the metal element comprised in the composite oxide are computed from the input ratio of the raw material of manufactures.

(57) Further, the structure of the active material was confirmed through XRD, and the results are shown in Table 2 below.

(58) TABLE-US-00002 TABLE 2 XRD List (003)/(104) R-factor a c Grain size (Å) c-axis/a-axis Comparative Example 1 1.621 0.413 2.872 14.2 563 4.943 Comparative Example 2 1.675 0.419 2.872 14.19 530 4.939 Comparative Example 3 1.622 0.406 2.872 14.18 554 4.938 Comparative Example 4 1.621 0.419 2.872 14.81 564 5.157 Comparative Example 5 1.705 0.421 2.872 14.19 569 4.94 Comparative Example 6 1.765 0.416 2.872 14.29 593 4.975 Comparative Example 7 1.65 0.408 2.871 14.19 555 4.943 Comparative Example 8 1.687 0.411 2.871 14.19 584 4.942 Comparative Example 9 1.6 0.437 2.872 14.19 542 4.94 Example 1 1.65 0.419 2.872 14.86 547 5.174 Example 2 1.657 0.42 2.872 14.19 524 4.941 Example 3 1.655 0.406 2.872 14.19 530 4.941 Example 4 1.687 0.411 2.871 14.2 562 4.946 Example 5 1.65 0.405 2.871 14.19 572 4.941 Example 6 1.65 0.413 2.871 14.2 560 4.946 Example 7 1.674 0.405 2.872 14.19 547 4.941

Example: Manufacturing of Coin Cell

(59) 90 wt % of each of the cathode active materials prepared in Examples and Comparative Examples, 5 wt % of carbon black as a conductive material, and 5 wt % of polyvinylidene fluoride (PVDF) as a binder were added to 5.0 wt % of N-methyl-2 pyrrolidone (NMP) as a solvent, thereby preparing cathode slurry.

(60) The cathode prepared slurry was applied onto an aluminum (Al) thin film (thickness: 20 to 40 μm) corresponding to a cathode current collector, vacuum-dried, and roll-pressed, thereby manufacturing a cathode.

(61) As an anode, a Li metal was used.

(62) A coin-cell type half-cell was manufactured using the cathode manufactured as described above, the Li metal as a counter electrode, and 1.0M LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) (1:1 vol %) as an electrolyte.

(63) Charge and discharge were performed in a range of 4.3 to 2.75V.

(64) The results are shown in Table 3 below.

(65) TABLE-US-00003 TABLE 3 1st 30th 50th 30/1 50/1 List CC DC Eff (%) CC DC Eff (%) CC DC Eff (%) % % Comparative Example 1 220.7 199 90.16 186.4 182.1 97.7 171.94 167.2 97.25 91.66 83.98 Comparative Example 2 222.3 200.7 90.3 195.6 191.3 97.8 182.38 177.5 97.31 95.1 88.18 Comparative Example 3 215.6 194.6 90.23 187.4 183.3 97.79 172.34 167.8 97.39 94.07 86.15 Comparative Example 4 214.1 191.5 89.42 192.6 190.2 98.76 187.99 171.3 91.13 99.37 89.48 Comparative Example 5 203.1 183.2 90.2 190.3 173.3 91.03 184.23 159.2 86.42 94.55 86.89 Comparative Example 6 198.5 180.5 90.97 186.2 168.6 90.56 174.55 149.3 85.55 93.4 82.71 Comparative Example 7 193.4 178.5 92.26 180.5 161.1 89.27 168.47 147.1 87.32 90.27 82.43 Comparative Example 8 212.4 193.1 90.92 188.5 180.9 95.98 169.54 164.4 96.96 93.59 85.06 Comparative Example 9 205.7 188.1 91.44 178 173.7 97.58 162.404 158.4 97.51 92.36 84.19 Example 1 210.5 190.8 90.64 190.2 189.8 99.75 186.74 176.2 94.38 99.49 92.39 Example 2 205.8 187.5 91.11 191.6 188.6 98.4 186.52 182.7 97.96 100.5 97.43 Example 3 204.6 188.9 92.29 192.5 190.4 98.92 188.29 186.1 98.85 100.8 98.56 Example 4 204.8 184.5 90.08 191.7 180.5 94.17 186.94 171 91.49 97.84 92.73 Example 5 204.8 190.1 92.83 192.5 190.5 99 188.54 186.2 98.78 100.2 97.96 Example 6 203.4 184.8 90.85 191.3 180.5 94.4 186.47 171.5 91.95 97.7 92.78 Example 7 203.4 185.2 91.05 191.3 181 94.66 186.47 172.5 92.48 97.75 93.11

(66) With respect to the cycle characteristics when Ti alone or Al alone, it may be confirmed that the discharge capacity retention rate is increased at 50 cycles than when two elements are simultaneously applied.

(67) However, even when using Ti and Al simultaneously, it may be confirmed that the cycle characteristics change with the change of the content of Ti.

(68) This may be confirmed that the cycle capacity retention rate is excellent when the average oxidation number N of the dopant is 3.05≤N≤3.35, and when the grain size is 500 to 550 Angstroms.

(69) After fixing the content of Al and Ti, it is confirmed that the initial discharge capacity decreases rapidly as the content of Mg increases.

(70) In addition, it is confirmed that the particle density is reduced, and the cycle characteristics is reduced.

(71) However, in the case of the addition of a small amount compared to the dopant together, even it may be confirmed that the cycle increases.

(72) The ratio at this time is a molar ratio, which is smaller than Al and Ti, and satisfies that 3<N when expressed by the oxidation number N of the dopant.

(73) It may be observed that Mg is participated in the ratio of I003/I104, and in the case of the addition of a predetermined amount, it may be confirmed that the effect is represented on the cycle performance by the relationship with other dopants.

(74) At this time, the preferable range of N is 3.05<N.

(75) Since the change in the Al content does not show a difference in a small range, when the range is widened, that is, when about 8000 ppm by addition amount is added, it confirms that it represents the implementation of preferable performance.

(76) At this time, the total amount of dopant addition is less than 15,000 ppm.

(77) At this time, the dopant oxidation number N converges to N, but satisfies the range of 3.05≤N≤3.35 by the tetravalent dopant.

(78) When seeing the results of when replacing part of Ti with Zr, it shows an effect with improvement in I003/I104, which indicates the degree of cation mixing.

(79) Because of this, it is confirmed that Ti and Zr may be used together as a tetravalent element.

DESCRIPTION OF SYMBOLS

(80) 30: Lithium Battery 22: Anode 23: Cathode 24: Separator 25: Battery container 26: Encapsulation member