• Title/Summary/Keyword: battery voltage drop

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Preparation and Electrochemical Properties of Pr1-x (Sr, Ca)xCoO3 Cathode Materials for Zinc Air Batteries (아연공기전지용 Pr1-x (Sr, Ca)xCoO3 양극촉매 제조 및 전기화학적 특성)

  • Heo, Sang-Hun;Eom, Seung-Wook;Kim, Hyun-Soo
    • Journal of the Korean Electrochemical Society
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    • v.12 no.4
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    • pp.342-348
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    • 2009
  • Zn/Air secondary batteries are high energy density type and environment-friendly. Also, they have safer properties than batteries of other type by low manufacturing cost and using the electrolyte solution. But, they have a weak concerning large output discharge. Oxygen evolution reaction(OER) and oxgen reduction reaction(ORR) in aqueous solution make a result of a decrease of cell efficiency and life span. Therefore, to minimize the voltage drop from between OCV and charge/discharge voltage is key point. The problem should be solved through developing catalysts of high efficiency. In this study, we synthesized $Pr_{1-x}(Sr,\;Ca)_x\;CoO_3$ powders by citric method and then measured physical characteristics of each powder by XRD, SEM, TGA etc. We examined its electrochemical properties by the cathodic polarization, anodic polarization and cyclic voltammogram. We achieved results that new catalysts showed better performances than existing $La_{1-x}Sr_xCoO_3$, $La_{1-x}Ca_xCoO_3$, ect. catalysts prepared in our lab.

Analysis for Atomic Structural Deterioration and Electrochemical Properties of Li-rich Cathode Materials for Lithium Ion Batteries (리튬이차전지용 리튬과잉계 양극 산화물의 충방전 과정 중 원자 구조 열화 과정과 전기화학 특성에 대한 분석)

  • Park, Seohyeon;Oh, Pilgun
    • Applied Chemistry for Engineering
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    • v.31 no.1
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    • pp.97-102
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    • 2020
  • Recently, various degradation mechanisms of lithium secondary battery cathode materials have been revealed. As a result, many studies on overcoming the limitation of cathode materials and realizing new electrochemical properties by controlling the degradation mechanism have been reported. Li-rich layered oxide is one of the most promising cathode materials due to its high reversible capacity. However, the utilization of Li-rich layered oxide has been restricted, because it undergoes a unique atomic structure change during the cycle, in turn resulting in unwanted electrochemical degradations. To understand an atomic structure deterioration mechanism and suggest a research direction of Li-rich layered oxide, we deeply evaluated the atomic structure of 0.4Li2MnO3_0.6LiNi1/3Co1/3Mn1/3O2 Li-rich layered oxide during electrochemical cycles, by using an atomic-resolution analysis tool. During a charge process, Li-rich materials undergo a cation migration of transition metal ions from transition metal slab to lithium slab due to the structural instability from lithium vacancies. As a result, the partial structural degradation leads to discharge voltage drop, which is the biggest drawback of Li-rich materials.