CATHODE ACTIVE MATERIAL FOR LITHIUM SECONDARY BATTERY [TECHNICAL FIELD] The present invention relates to a cathode active material for secondary batteries. More specifically, the present invention relates to a cathode active material for secondary batteries that exhibits a high capacity and superior rate characteristics based on a specific composition. [BACKGROUND ART] Technological development and increased demand for mobile equipment have 10 led to a rapid increase in the demand for secondary batteries as energy sources. Among these secondary batteries, lithium secondary batteries having high energy density and voltage, long lifespan and low self-discharge are commercially available and widely used. In addition, increased interest in environmental issues has brought about a great 15 deal of research associated with electric vehicles (EVs) and hybrid electric vehicles (HEVs) as substitutes for vehicles using fossil fuels such as gasoline vehicles and diesel vehicles which are major causes of air pollution. These electric vehicles generally use -1- nickel metal hydride (Ni-MH) secondary batteries as power sources of electric vehicles (EVs), hybrid electric vehicles (HEVs) and the like. However, a great deal of study associated with use of lithium secondary batteries with high energy density and discharge voltage is currently underway and some are commercially available. 5 In particular, lithium secondary batteries used for electric vehicles should have high energy density, exhibit great power within a short time and be used for 10 years or longer under harsh conditions in which charge and discharge based on high current are repeated within a short time, thus requiring considerably superior stability and long lifespan, as compared to conventional small lithium secondary batteries. 10 Conventional lithium secondary batteries generally utilize a lithium cobalt composite oxide having a layered structure for a cathode and a graphite-based material for an anode. However, such lithium cobalt composite oxide is disadvantageously unsuitable for electric vehicles in terms of presence of extremely expensive cobalt as a main element and low safety. In order to solve these disadvantages, materials such as 15 Li(NiMnyCoZO2) (x+y+z=1) are used. In order to secure structural stability of such a layer-structure cathode active material, many researchers have studied cathode active materials with a layered structure containing Li2MnO3. The cathode active materials with a layered structure containing Li2MnO3 is characterized in that Li is contained in a general transition metal -2- layer made of LiMO2 (M: transition metal) and they have super lattice peaks caused by the Li2MnO3 structure. Such a material advantageously contains a great amount of Mn and is thus considerably cheap and exhibits considerably high capacity at a high voltage. The material has a flat voltage region of 4.4 to 4.6V. After activation occurs 5 in the flat region, capacity increases. This increase in capacity is known to be caused by deintercalation of Li from the transition metal layer due to generation of oxygen, but is still controversial. Capacity increases after the activation region, but rate characteristics are clearly rapidly deteriorated. Due to these characteristics, this material is practically 10 inapplicable to batteries at present. In order to solve these problems in the related art, a method in which the active material is coated with particles after it is synthesized, has been attempted, but this method disadvantageously causes an increase in preparation cost. Furthermore, this method uses a post-treatment manner and does not contribute to variation and 15 improvement in substantial internal structure, most structural variation is caused by formation process of crystalline at a high temperature of the synthesis process. [DISCLOSURE] [TECHNICAL PROBLEM) -3- Therefore, the present invention has been made to solve the above and other technical problems that have yet to be resolved. As a result of a variety of extensive and intensive studies and experiments to solve the problems as described above, the present inventor developed a cathode active 5 material for secondary batteries having a mix composition of Formula 1 as a cathode active material for secondary batteries and discovered that, when a secondary battery is fabricated using this cathode active material, the secondary battery exhibits an increase in capacity after the activation region as well as superior rate characteristics. The present invention has been completed, based on this discovery. 10 [TECHNICAL SOLUTION] In accordance with one aspect of the present invention, provided is a cathode active material for secondary batteries, comprising at least one compound selected from the following Formula 1: xLi2MO3*yLiM'02*zLi3PO4 (1) 15 wherein M is at least one element selected from 1 period or 2 period metals having an oxidation number of +4, M' is at least one element selected from 1 period or 2 period metals having a mean oxidation number of +3, 0.15 x<_ 0.9, 0.1:5 y< 0.9, 0 A transition metal composite precursor was synthesized by a coprecipitation method such that a ratio of transition metals was adjusted to Nio.25Mno,75, primarily 5 mixed with Li2CO3 as a lithium precursor, and then secondarily mixed with Li3PO4 such that a molar ratio of the primary mixture and Li3PO4 was 0.97: 0.03. The secondary mixture was incorporated into an electric furnace, was slowly heated from room temperature, maintained at 960°C for 10 hours, and cooled in an ice bath to synthesize 0.485Li2MnO3*0.485LiNio.5Mno.502*0.03Li3PO4 as a cathode active material. 10 0.5Li2MnO3*0.5LiNio,5Mno,502 was synthesized as a cathode active material in the same manner as in Example 1 except that Li3PO4 was not mixed. A transition metal composite precursor was synthesized by a coprecipitation 15 method such that a ratio of transition metals was adjusted to Nio.1875Mno.6s75Coo.125, primarily mixed with Li2CO3 as a lithium precursor, and then secondarily mixed with Li3PO4 such that a molar ratio of the primary mixture and Li3PO4 was 0.97 : 0.03. The secondary mixture was incorporated into an electric furnace, was slowly heated from -14- room temperature and maintained at 960°C for 10 hours, and cooled in an ice bath to synthesize 0.485Li2MnO3*0.485LiNio.37sMno.375Coo.2502*0.03Li3PO4 as a cathode active material. 5 0.5Li2MnO3*0.5LiNio.375Mno.37sCoo.2502 was synthesized as a cathode active material in the same manner as in Example 2 except that Li3PO4 was not mixed. A cathode mix in which a ratio of cathode active material : conductive material : binder was 90:6:4 was prepared using each of the cathode active materials 10 prepared in Examples 1 to 2 and Comparative Examples 1 to 2. The cathode was pressed using the cathode mix to obtain two coin-type batteries. An anode active material used herein was a Li-metal and an electrolyte used herein was an electrolytic solution in which 1 M LiPF6 was dissolved in a carbonate electrolyte. The battery thus fabricated was discharged at 0.1C up to 4.8V and discharged at 0.1C up to 2.5V at the 15 1St cycle, and charged at 0.2C to 4.5V and discharged at 0.2C to 2.5V at the 2"d cycle. Then, to measure rate characteristics, the battery was discharged at O.1C, 0.2C, 0.5C, 1.OC, 1.5C and 2.OC up to 2.5V as the 3d to 8th cycles based on charge at 0.5C up to 4.5V. The initial discharge capacity, initial charge/discharge efficiency and rate characteristics were measured. The results are shown in Table 1 below. -15- 1St cycle discharge 1St 8t cycle/3` cycle charge/discharge discharge capacity capacity (mAh/g) efficiency (%) ratio (%) Ex. 1 259 82 72 Comp. Ex. 1 262 78 56 Ex. 2 241 83 80 Comp. Ex. 2 245 81 63 As can be seen from Table 1 above, the battery using the cathode active material having a mixed composition of the present invention exhibited a slight decrease in initial capacity, as compared to a battery containing no lithium phosphate, 5 which is a considerably slight level that does not have an effect on electrochemical performance. Batteries using cathode active materials of Examples exhibited increases in charge and discharge efficiencies and, in particular, improvement in rate characteristics during high-rate discharge (in particular, 2.OC discharge at the 8t" cycle). Batteries used as a power source of vehicles and the like should be charged and 10 discharged while exhibiting rate characteristics due to inherent characteristics thereof. In addition, small batteries also exhibit different behaviors according to the thickness of constituent electrodes and superior rate characteristics are considerably important requirements. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. 5 INDUSTRIAL APPLICABILITY] As apparent from the afore-going, a non-aqueous electrolyte secondary battery based on a cathode comprising a cathode active material having a specific mix composition provides a secondary battery that exhibits a high capacity and superior rate characteristics. 10 [CLAIMS] (Claim 1 ] A cathode active material for secondary batteries, comprising at least one compound selected from the following Formula 1: xLi2MO3*yLiM'O2*zLi3PO4 (1) 5 wherein M is at least one element selected from 1 period or 2 period metals having an oxidation number of +4; M' is at least one element selected from 1 period or 2 period metals having a mean oxidation number of +3; and 0.15 x5 0.9, 0.15 y5 0.9, 0

Documents

Application Documents

#	Name	Date
1	Power of Authority.pdf	2012-11-07
2	Form-5.pdf	2012-11-07
3	Form-3.pdf	2012-11-07
4	Form-1.pdf	2012-11-07
5	9501-delnp-2012-Form-18-(27-11-2012).pdf	2012-11-27
6	9501-delnp-2012-Correspondence Others-(27-11-2012).pdf	2012-11-27
7	9501-DELNP-2012-FER.pdf	2018-07-16
8	9501-DELNP-2012-Verified English translation (MANDATORY) [12-09-2018(online)].pdf	2018-09-12
9	9501-DELNP-2012-Proof of Right (MANDATORY) [12-09-2018(online)].pdf	2018-09-12
10	9501-DELNP-2012-PETITION UNDER RULE 137 [12-09-2018(online)].pdf	2018-09-12
11	9501-DELNP-2012-OTHERS-140918.pdf	2018-09-18
12	9501-DELNP-2012-Correspondence-140918.pdf	2018-09-18
13	9501-DELNP-2012-OTHERS-260918.pdf	2018-10-03
14	9501-DELNP-2012-Correspondence-260918.pdf	2018-10-03
15	9501-DELNP-2012-PETITION UNDER RULE 137 [08-01-2019(online)].pdf	2019-01-08
16	9501-DELNP-2012-OTHERS [08-01-2019(online)].pdf	2019-01-08
17	9501-DELNP-2012-FER_SER_REPLY [08-01-2019(online)].pdf	2019-01-08
18	9501-DELNP-2012-CLAIMS [08-01-2019(online)].pdf	2019-01-08
19	9501-DELNP-2012-ABSTRACT [08-01-2019(online)].pdf	2019-01-08
20	9501-DELNP-2012-PatentCertificate18-01-2019.pdf	2019-01-18
21	9501-DELNP-2012-IntimationOfGrant18-01-2019.pdf	2019-01-18
22	9501-DELNP-2012-Response to office action (Mandatory) [30-01-2019(online)].pdf	2019-01-30
23	9501-DELNP-2012-RELEVANT DOCUMENTS [21-02-2020(online)].pdf	2020-02-21
24	9501-DELNP-2012-RELEVANT DOCUMENTS [23-08-2021(online)].pdf	2021-08-23
25	9501-DELNP-2012-RELEVANT DOCUMENTS [27-09-2021(online)].pdf	2021-09-27
26	9501-DELNP-2012-RELEVANT DOCUMENTS [15-09-2022(online)].pdf	2022-09-15
27	9501-DELNP-2012-POWER OF AUTHORITY [30-11-2022(online)].pdf	2022-11-30
28	9501-DELNP-2012-FORM-16 [30-11-2022(online)].pdf	2022-11-30
29	9501-DELNP-2012-ASSIGNMENT WITH VERIFIED COPY [30-11-2022(online)].pdf	2022-11-30

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1	9501DELNP2012_02-07-2018.pdf