• (DESCRIPTION) CATHODE ACTIVE MATERIAL FOR SECONDARY BATTERIES (TECHNICAL FIELD) The present invention relates to a cathode active material for secondary 5 batteries. More specifically, the present invention relates to a cathode active material for secondary batteries that exhibits a high capacity and superior stability at a high voltage, 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 driving 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, such as gasoline vehicles and diesel vehicles, using fossil fuels which are major causes of air pollution. Nickel metal hydride (Ni-MH) -1- 5 secondary batteries are generally used 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, high energy density high discharge voltage and power stability is currently underway and some are commercially available. In particular, lithium secondary batteries used for electric vehicles should have high energy density, exert high power within a short time and be used for 10 years or longer under harsh conditions, thus requiring considerably superior stability and long lifespan, as compared to conventional small lithium secondary batteries. In addition, secondary batteries used for electric vehicles (EVs), hybrid electric vehicles (HEVs) and 10 the like require rate characteristics and power characteristics according to driving conditions of vehicles. 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 a lithium cobalt composite oxide is disadvantageously 15 unsuitable for electric vehicles in terms of presence of extremely expensive cobalt as a main element and low safety. Accordingly, lithium manganese composite oxides having a spinel structure that comprise cheap and highly stable manganese are suitable for cathodes of lithium ion batteries for electric vehicles. -2- • However, in case of lithium manganese composite oxides, manganese is eluted into an electrolyte during charge and discharge at high temperatures and high currents, causing deterioration in battery characteristics. Accordingly, there is a need for a solution to prevent this phenomenon. Also, lithium manganese composite oxides 5 disadvantageously have smaller capacity per unit weight than conventional lithium cobalt composite oxides or lithium nickel composite oxides, thus having a limitation of increase in capacity per weight. Design of batteries to overcome this limitation is required so that lithium manganese composite oxides can be commercially applied to power sources for electric vehicles. 10 In order to solve these disadvantages, materials such as Li(NixMnyCoz02) (x+y+z=l) are used. In order to secure structural stability of such a layered-structure cathode active material, many researchers have studied cathode active materials with a layered structure containing LhMn03. The cathode active materials with a layered structure containing LhMn03 are 15 characterized in that Li is contained in a general transition metal layer made of LiM02 (M: transition metal) and they have super lattice peaks caused by the LhMn03 structure. Such a material contains a great amount of Mn, thus being advantageously considerably cheap and exhibiting considerably high capacity and superior stability at a high voltage. The material has a broad voltage area of 4.4 to 4.6V. After activation occurs in the 20 broad region, capacity increases. This increase in capacity is known to be caused by -3- • deintercalation of Li from the transition metal layer due to generation of oxygen, but opinions associated with the cause are still controversial. Clearly, after the activation domain, structural variation is serious and electrical properties are thus deteriorated. The reason for this is known that structural variation 5 causes conversion from a layered structure into a spinel structure and thus makes contact between domains loose. For these reasons, practical application of this substance to batteries is impossible at present. In order to solve these problems, in the related art, a method in which particles of the active material are coated after synthesis, has been attempted, but this method 10 disadvantageously causes an increase in preparation cost. Furthermore, as this method uses a post-treatment manner and does not substantially contribute to variation and improvement of inner structure, most structural variation is caused by formation of crystallinity at a high temperature of the synthesis process. (DISCLOSURE] 15 (TECHNICAL PROBLEM] Therefore, the present invention has been made to solve the above and other technical problems that have yet to be resolved. -4- • As a result of a variety of extensive and intensive studies and experiments, the present inventor developed a cathode active material for secondary batteries having a composition of Formula 1 as a cathode active material for secondary batteries and discovered that a secondary battery fabricated using this cathode active material exhibits 5 an increase in capacity and superior rate characteristics after an activation domain passes. The present invention has been completed, based on this discovery. [TECHNICAL SOLUTION) In accordance with one aspect of the present invention, provided is a cathode active material for secondary batteries represented by the following formula 1: 10 wherein O -14- • A transition metal composite precursor was synthesized by a coprecipitation method such that a ratio of transition metals was adjusted to Nis12l MnI6/21, primarily mixed with LhC03 as a lithium precursor, and then secondarily mixed with LbP04 such that a molar ratio of the primary mixture and LbP04 was 0.97 : 0.03. The secondary 5 mixture was incorporated into an electric furnace, was slowly heated from room temperature, maintained at 960°C for 10 hours, and cooled in the air to synthesize material. A cathode mix was prepared such that a ratio of cathode active material : 10 conductive material: binder was 90:6:4. The cathode was punched into a coin shape using the cathode mix to obtain a coin-type battery. An anode active material used herein was a Li-metal and an electrolyte used herein was an electrolytic solution of 1M LiPF6 in a carbonate electrolyte (ECIEMC=I:2). 15 A transition metal composite precursor was synthesized by a coprecipitation method such that a ratio of transition metals was adjusted to Ni4I2lMnISI2lC02/2I, primarily mixed with LhC03 as a lithium precursor, and then secondarily mixed with LbP04 such that a molar ratio of the primary mixture to LbP04 was 0.97:0.03. The secondary mixture was incorporated into an electric furnace, was slowly heated from -15- • room temperature and maintained at 960°C for 10 hours, and cooled in the air to synthesize 0.97(0.45LhMn03*0.5LiNio4Mno4Coo.202*0.05LiMn204)*0.03LhP04 as a cathode active material. A coin-type battery was fabricated in the same manner as in Example 1, except that the cathode active material was used. 5 A coin-type battery was fabricated in the same manner as in Example 1 except that 0.45LhMn03*0.5LiNio.sMnos02*0.05LiMn204 was prepared as a cathode active material. 10 A coin-type battery was fabricated in the same manner as in Example 2 except that 0.45LhMn03*0.5LiNio4Mno4Coo.202*0.05LiMn204 was synthesized as a cathode active material. The batteries of Examples 1 and 2 and Comparative Examples 1 and 2 were 15 charged at O.lC to 4.8V and discharged at O.IC to 2.5V at a 1st cycle, and charged at 0.2C to 4.5V and discharged at 0.2C to 2.5V at a 2nd cycle. Then, to evaluate rate characteristics, the batteries were discharged at 0.1 C, 0.2C, 0.5C, I.OC, I.5C and 2.0C to 2.5V at 3rd to 8th cycles, based on charging at 0.5C to 4.5V. Initial discharge -16- • capacity, initial charge/discharge efficiency and rate characteristics were measured. The results are shown in Table 1 below. Then, the charge and discharge cycle was repeated 30 times at 0.5C and cycle efficiency of discharge capacity, based on 9th/39th cycle, is shown in Table I below. 5 1st cycle 8th /3rd cycle 9th /39th 1st . cycle discharge discharge capacity charge/discharge capacity ratio discharge efficiency (%) capacity (mAh/g) (%) ratio (%) Ex. 1 255 85 74 93 Ex. 2 243 86 82 92 Compo Ex. 1 253 81 72 86 Comp. Ex. 2 244 82 80 84 As can be seen from Table I above, the batteries (Examples 1 and 2) using the cathode active material having a mixed composition ofthe present invention exhibited a slight decrease in initial capacity, as compared to batteries (Comparative examples 1 and 2) containing no lithium phosphate and this decrease was a considerably slight level 10 that did not have an effect on electrochemical performance. On the other hand, batteries using cathode active materials of examples exhibited increases in charge and discharge efficiencies and improvement in rate and cycle characteristics. The active material structurally collapsed during charge and discharge. In the structural collapse process, stable LbP04 is thought to inhibit structural collapse. 15 Also, this inhibition in structural collapse affects improvement in rate characteristics. -17- • Batteries used as power sources of vehicles and the like should be charged and discharged at a high rate due to inherent characteristics thereof. In addition, smallsized batteries also exhibit different behaviors according to the thickness of constituent electrodes, and superior rate and cycle characteristics are thus considerably important 5 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 ofthe invention as disclosed in the accompanying claims. 10 [INDUSTRIAL APPLICABILITY) As apparent from the afore-going, the non-aqueous electrolyte secondary battery based on a cathode comprising a cathode active material having a specific composition according to the present invention provides a secondary battery that exhibits high capacity and superior electric properties. 15 [Claim 1) [CLAIMS] A cathode active material represented by the following Formula 1, the 5 10 cathode active material being in the form of a solid solution or a composite: wherein O

Documents

Application Documents

#	Name	Date
1	1816-delnp-2013-GPA.pdf	2013-08-20
2	1816-delnp-2013-Form-5.pdf	2013-08-20
3	1816-delnp-2013-Form-3.pdf	2013-08-20
4	1816-delnp-2013-Form-2.pdf	2013-08-20
5	1816-delnp-2013-Form-18.pdf	2013-08-20
6	1816-delnp-2013-Form-1.pdf	2013-08-20
7	1816-delnp-2013-Description(Complete).pdf	2013-08-20
8	1816-delnp-2013-Correspondence-others.pdf	2013-08-20
9	1816-delnp-2013-Claims.pdf	2013-08-20
10	1816-delnp-2013-Abstract.pdf	2013-08-20
11	1816-DELNP-2013.pdf	2016-11-15
12	1816-DELNP-2013-FER.pdf	2018-05-18
13	1816-DELNP-2013-Verified English translation (MANDATORY) [11-08-2018(online)].pdf	2018-08-11
14	1816-DELNP-2013-Proof of Right (MANDATORY) [11-08-2018(online)].pdf	2018-08-11
15	1816-DELNP-2013-PETITION UNDER RULE 137 [11-08-2018(online)].pdf	2018-08-11
16	1816-DELNP-2013-PETITION UNDER RULE 137 [11-08-2018(online)]-1.pdf	2018-08-11
17	1816-DELNP-2013-Information under section 8(2) (MANDATORY) [11-08-2018(online)].pdf	2018-08-11
18	1816-DELNP-2013-FORM 3 [11-08-2018(online)].pdf	2018-08-11
19	1816-DELNP-2013-OTHERS-210818.pdf	2018-08-27
20	1816-DELNP-2013-Correspondence-210818.pdf	2018-08-27
21	1816-DELNP-2013-OTHERS-240818.pdf	2018-08-28
22	1816-DELNP-2013-Correspondence-240818.pdf	2018-08-28
23	1816-DELNP-2013-OTHERS [24-09-2018(online)].pdf	2018-09-24
24	1816-DELNP-2013-FER_SER_REPLY [24-09-2018(online)].pdf	2018-09-24
25	1816-DELNP-2013-COMPLETE SPECIFICATION [24-09-2018(online)].pdf	2018-09-24
26	1816-DELNP-2013-CLAIMS [24-09-2018(online)].pdf	2018-09-24
27	1816-DELNP-2013-ABSTRACT [24-09-2018(online)].pdf	2018-09-24
28	1816-DELNP-2013-FORM-26 [25-09-2018(online)].pdf	2018-09-25
29	1816-DELNP-2013-Power of Attorney-260918.pdf	2018-10-03
30	1816-DELNP-2013-Correspondence-260918.pdf	2018-10-03
31	1816-DELNP-2013-Response to office action [24-09-2020(online)].pdf	2020-09-24
32	1816-DELNP-2013-Response to office action [14-09-2021(online)].pdf	2021-09-14
33	1816-DELNP-2013-US(14)-HearingNotice-(HearingDate-09-11-2021).pdf	2021-10-17
34	1816-DELNP-2013-FORM-26 [10-11-2021(online)].pdf	2021-11-10
35	1816-DELNP-2013-US(14)-HearingNotice-(HearingDate-02-12-2021).pdf	2021-11-17
36	1816-DELNP-2013-FORM-26 [30-11-2021(online)].pdf	2021-11-30
37	1816-DELNP-2013-Correspondence to notify the Controller [30-11-2021(online)].pdf	2021-11-30
38	1816-DELNP-2013-Written submissions and relevant documents [14-12-2021(online)].pdf	2021-12-14
39	1816-DELNP-2013-PatentCertificate21-12-2021.pdf	2021-12-21
40	1816-DELNP-2013-IntimationOfGrant21-12-2021.pdf	2021-12-21
41	1816-DELNP-2013-POWER OF AUTHORITY [30-11-2022(online)].pdf	2022-11-30
42	1816-DELNP-2013-FORM-16 [30-11-2022(online)].pdf	2022-11-30
43	1816-DELNP-2013-ASSIGNMENT WITH VERIFIED COPY [30-11-2022(online)].pdf	2022-11-30
44	1816-DELNP-2013-RELEVANT DOCUMENTS [23-08-2023(online)].pdf	2023-08-23

Search Strategy

1	searchstrategy_19-12-2017.pdf