CATHODE ACTIVE MATERIAL AND LITHIUM SECONDARY BATTERIES COMPRISING THE SAME

• Main Authors: MOON, JONG SEOK, CHOI, SHIN JUNG, LEE, MI SUN
• Format: Patent
• Language: English; Korean
• Published: 23.06.2015
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRICITY; PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSIONOF CHEMICAL INTO ELECTRICAL ENERGY

The present invention relates to a positive electrode active material comprising a fluorine doped lithium metal composite oxide in a layer structure. As a result of measuring impedance of a half cell applying to the positive electrode active material, [resistance of an electrolyte (RS) + resistance of solid electrolyte interface (RSEI) formed on surfaces of an electrode + resistance of charge transfer (RCT)] per unit area (cm^2) of a positive electrode is 8-30 Ω. According to the present invention, provided is a lithium secondary battery having low impedance by using the fluorine doped lithium metal composite oxide as the positive electrode active material so that discharge capacity and rate characteristic of the lithium secondary battery can be improved. 본 발명은 불소 도핑된 층상구조의 리튬 금속 복합산화물을 포함하고, 상기 양극 활물질을 적용한 반쪽 전지의 임피던스를 측정한 결과 양극 전극의 단위 면적(cm)당 [전해액의 저항(R) + 전극 표면에 형성된 SEI(solid electrolyte interface) 저항(R+ 전하 이동 저항(R)]가 8Ω 이상 30Ω 이하인 양극 활물질에 관한 것으로서, 본 발명에 따르면 불소가 도핑된 리튬 금속 복합산화물을 양극 활물질로 이용함으로써 낮은 임피던스를 갖는 리튬 이차전지를 제공할 수 있고, 이로 인하여 리튬 이차전지의 방전용량 및 율특성을 향상시킬 수 있다.