상세정보
학술지
High-rate Cycling Performance and Surface Analysis of LiNi1-xCox/2Mnx/2O2 (x=2/3, 0.4, 0.2) Cathode Materials
- 발행일
- 201901
- 출처
- Materials Chemistry and Physics, v.222, pp.1-10
- ISSN
- 0254-0584
- 출판사
- Elsevier
- 협약과제
- 18PB2600, 전기차 주행거리 연장을 위한 고에너지밀도 (300 Wh/kg) 리튬이차전지용 전해액 상용화기술 개발, 김광만
- 초록
- The electrochemical performance of layered LiNi1-xCox/2Mnx/2O2 cathode materials (x = 2/3, 0.4, 0.2; so-called NCM333, NCM622, NCM811) in 1.0 M LiPF6-dissolved conventional carbonate-based electrolyte during formation at a 0.1 C-rate and consequent cycling at a 1.0 C-rate is measured and considered together with the results of morphology observation, impedance spectroscopy, and surface analysis. X-ray photoelectron spectroscopy (XPS) is carried out on the surface of the cathode materials before and after formation and cycling to investigate the effects of solid electrolyte interphase (SEI) formation on the electrochemical performance. As the Ni content increases, the initial specific capacity increases but the capacity retention ratio decreases. High-rate cycling overrides the SEI formation on the NCM surfaces, but NCM622 suffers great changes in the SEI components with a thick layer resulting in large interfacial resistance. It is also proved that NCM811 shows significant dissolution and accumulation of Ni species on the surface, contributing structural degradation and leading to fast capacity fading.
- KSP 제안 키워드
- Capacity fading, Carbonate-based electrolyte, Cathode materials, Electrochemical performance, High rate, Impedance spectroscopy(IS), Ni content, Ni species, SEI formation, Structural degradation, Thick layer