• Journal of the Korean Electrochemical Society
• /
• v.2 no.1
• /
• pp.46-49
• /
• 1999

Lithium cobalt oxide cathode for thin-film rechargeable lithium batteries were fablicated by electron-beam evaporation. Annealed lithium cobalt oxide, which was deposited on to stainless steel substrate, showed well-developed (003) planes of the hexagonal structure and potential plateau at $\~3.9 V$. Lithium cobalt oxide thin films had the stoichiometric Li/co ratio at high deposition rates and exhibited high discharge capacity at $15{\AA}/s$. As the annealing temperature increased, discharge capacity increased with maximum value at $700^{\circ}C$, but showed low capacity as a result of reaction with substrate above $700^{\circ}C$. Unuiformity of the lithium and cobalt in the depth profile gave initial capacity loss with charge/discharge performance.

• Journal of the Korean Electrochemical Society
• /
• v.11 no.4
• /
• pp.242-255
• /
• 2008

In lithium-ion batteries(LIB), the development of electrolytes had mainly focused on the characteristics of lithium cobalt oxide($LiCoO_2$) cathode and graphite anode materials since the commercialization in 1991. Various studies on compatibility between electrode and electrolytes had been actively developed on their interface. Since then, as they try to adopt silicon and tin as anode materials and three components(Ni, Mn, Co), spinel, olivine as cathode materials for advanced lithium batteries, conventional electrolyte materials are facing a lot of challenges. In particular, requirements for electrolytes performance become harsh and complicated as safety problems are seriously emphasized. In this report, we summarized the research trend of electrolyte materials for the electrode materials of lithium rechargeable batteries.

• Journal of the Korean Chemical Society
• /
• v.50 no.3
• /
• pp.243-246
• /
• 2006

The LiCoO2 thin films were prepared on the Pt/Ti/SiO2/Si substrate by spin coating using citrate sol. The citrate sol was spin-coated on substrate and dried at 380oC for 15 min. to evaporate the solvents and remove the organic materials. The as-deposited films were annealed at 750oC for 10 min. in air for crystallization. The X-ray diffraction patterns for the film have been indexed hexagonal system with space group R3m. The active area of LiCoO2 films for electrochemical test was about 11cm2. A Li foil and 1M LiClO4 in propylene carbonate(PC) and ethylene carbonate(EC) (1:1)were used as an anode and an electrolyte, respectively. The galvanostatic charge-discharge test was carried out at constant current density ranging from 5 A/cm2 in the voltage window between 4.2 and 3.0 V. The first discharge capacity of the film is 0.35Ah/cm2-m. The cycling behavior of the LiCoO2 film is also reported.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.05a
• /
• pp.228-231
• /
• 1996

We prepared $LiCo_{1-x}Ni_{x}O_2$ by reacting stoichiometric mixture of LiOH.$H_2O$, $CoCO_3$.$xH_2O$ and $Ni(OH)_2$ (mole ratio respectively) and heating at $850^{\circ}C$ for 5h. We awared through XRD that from 0 to 0.5 at x in $LiCo_{1-x}Ni_{x}O_2$ is well formed for hexagonal structure, but the more $LiCo_{1-x}Ni_{x}O_2$ involve NI, the more hexagonal structure is not well formed. In the result of charge/discharge test, charge/discharge characteristic of $LiCo_{1-x}Ni_{x}O_2$ is similar to that of $LiCoO_2$. Therefore, $LiCo_{1-x}Ni_{x}O_2$ is superior to $LiCoO_2$ for Li secondary battery

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.20 no.5
• /
• pp.443-449
• /
• 2007

The structural and thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ electrode during cycling process was studied. The sample was prepared by simple combustion method. Although there were irreversible changes on the initial cycle, O3 stacking for $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ structure was retained during the first and subsequent cycling process. Impedance of the test cell was decreased after the first charge-discharge process, which would be of benefit to intercalation and deintercalation of lithium ion on subsequent cycling. As expected, cycling test for 75 times increased impedance of the cell a little, instead, thermal stability of $Li[Co_{0.1}Ni_{0.15}Li_{0.2}Mn_{0.55}]O_2$ was improved. Moreover, based on DSC analysis, the initial exothermic peak was shifted to high temperature range and the amount of heat was also decreased after cycling test, which displayed that thermal stability was not deteriorated during cycling.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1995.11a
• /
• pp.340-342
• /
• 1995

We prepared $LiCo_{1-x}Ni_{x}O_2$ by reacting stoichiometric mixture of LiOH.$H_2O$, $CoCO_3$.$xH_2O$ and $Ni(OH)_2$(mole ratio respectively) and heating at $850^{\circ}C$ for 5n. In the result of X-ray diffraction analysis, along fluctuation of the function of x in $LiCo_{1-x}Ni_{x}O_2$(003) peak and (104) peak indensities and ratio were varied. We awared through XRD that from 0 to 0.5 at x in $LiCo_{1-x}Ni_{x}O_2$ is well formed for hexagonal structure at one step heat treatment($850^{\circ}C$), but if Ni involve at $LiCo_{1-x}Ni_{x}O_2$ hexagonal structure is not well formed. In the result of charge/discharge tests charge/discharge capacity and effiency is different about various cathode. Therefore, the appropriate charge/discharge method must be selected for good characteristics.

• Applied Chemistry for Engineering
• /
• v.16 no.4
• /
• pp.507-512
• /
• 2005

When carbon electrode is used as an anode in Li ion battery, passivation film forms on the electrode surface during the initial charge process due to so called Solid-Electrolyte Interphase (SEI). The passivation film formed by solvent decomposition during the initial charge process affects charge/discharge capacity. In this paper, 1 M $LiPF_6,EC:DEC$ (1 : 1, volume ratio) electrolyte with $Li_2CO_3$, at various temperatures, the electrochemical characteristics of passivation film formed on Kawasaki Mesophase Fine Carbon electrode surface were investigated by using chronopotentiometry, cyclic voltammetry, and impedance spectroscopy. Experimental observations indicated that as solvent decomposition occurred, the decomposition voltage was strongly dependent on ionic conductivity, which was low in the process at low temperature. The impedance of passivation film formed during the initial charge process, were dependent on the temperature.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.11
• /
• pp.1029-1035
• /
• 2008

$LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ cathode materials prepared from different precursors in lithium rechargeable batteries were characterized by various analytical methods. $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ powders were synthesized by using solid-state reaction method and their physical and chemical properties were analyzed by XRD, SEM, particle size analyzer and TCP-AES. These materials showed different crystallinity, particle size, surface morphology and chemical composition. Also, the charge/discharge cycling of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ electrodes was carried out under various cut-off voltages and it showed different behaviors. It was found that the electrochemical cyclability of $LiNi_{1/3}Co_{1/3}Mn_{1/3}O_2$ was strongly related to its crystallinity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.107-110
• /
• 1997

LiMn$_2$O$_4$ is prepared by reacting stoichiometric mixture of LiOH . $H_2O$ and MnO$_2$ (mole ratio 1 ; 1) and heating at 80$0^{\circ}C$, $700^{\circ}C$ for 24h, 36h, 48h, 60h and 72h. We obtained through X-ray diffraction that lattice parameter varied as function of calcined temperature and time. Cathode active materials calcined at 80$0^{\circ}C$ for 36h, (111)/(311) peak ratio was 0.37. It showed good charge/discharge characteristics. When (111)/(311) peak ratio was 0.37, it was that crystal structure is formed very well. In the result of charge/discharge test, when heated at 80$0^{\circ}C$ for 36h, charge/discharge characteristics of LiMn$_2$O$_4$ is the best.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.201.2-201.2
• /
• 2015

현대 디지털 사회에서 고효율 에너지와 파워소스에 관한 요구가 커짐에 따라 차세대 에너지 저장 소자에 대한 연구가 계속되고 있다. 그 중 리튬이온 배터리, 슈퍼커패시터, 그리고 연료 전지들이 우리의 일상생활에서 점점 더 중요하게 자리잡아가고 있는데 이런 다양한 에너지 저장소자 중 슈퍼커패시터가 많은 관심을 받고 있다. 이는 긴 수명, 빠른 충-방전 속도, 높은 에너지 밀도, 그리고 안전함 때문이다. 슈퍼커패시터는 에너지 저장 메커니즘에 따라 두 가지로 분류될 수 있는데 전기이중층 커패시터(EDLC)와 슈도커패시터(pseudocapacitor)로 나누어질 수 있다. 슈도커패시터는 active 물질과 전해질 이온 간의 전기화학적 반응으로 인해 EDLC보다 더 많은 에너지를 저장할 수 있다. 그러므로 지금까지 새로운 형태의 슈도용량성 물질을 만들기 위한 노력이 집중되고 있다. 본 연구에서는 전기화학적증착 방법을 통해 graphene-like ${\beta}$-nickel hydroxide (${\beta}-Ni(OH)_2$) 나노판 구조를 전도성 직물에 합성하였다. ${\beta}-Ni(OH)_2$ 슈도커패시터의 유연하고 효율적인 비용의 전극으로서 높은 비정전용량, 우수한 전기화학 가역성, 그리고 뛰어난 사이클 안정성을 보였다. 이런 쉬운 방법으로 유연한 전도성 직물에 합성된 metal hydroxide/oxide 나노구조는 웨어러블 에너지 저장소자와 변환소자 분야에 사용될 것으로 기대된다.