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成果報告書詳細
管理番号20190000000581
タイトル*2018年度中間年報 革新型蓄電池実用化促進基盤技術開発(国立大学法人東北大学)
公開日2019/6/14
報告書年度2018 - 2018
委託先名国立大学法人東北大学
プロジェクト番号P16001
部署名次世代電池・水素部
和文要約
英文要約RISING2 (FY2016-FY2020) FY2018 Annual Report, Tohoku University, Japan

We measured temperature dependence of diffusion coefficients for various electrolytes for revolutional batteries by pulse-field-gradient(PFG)-NMR method. We analyzed the mobilities and the structure of the electrolyte materials from the NMR results and computer simulations. Some electrolytes show not only the main solvent peaks expected from the nominal composition but also weak unknown peaks in the 1H NMR spectra. We found a correlation between the quantity of electrochemical reaction and a specific weak NMR signal intensity. We propose a possible structure model of the electrolyte solution from the results of a double resonance NMR, the temperature dependence of NMR spectra and DOSY diffusion analysis. The solvent peaks were identified from the spectrum shape and the diffusion coefficients for 13C and 1H. The solvated cations show diffusion coefficients smaller than the solvents. We observed various solvated states of anions. The anions that show smaller diffusion coefficients than solvent or cations are attributed to the formation of large size complex ions. Besides, in some specific electrolytes the anions show higher diffusion coefficients than the solvent. We have been investigating structure and ion transport mechanism of such electrolytes in detail. We measured diffusion coefficient of PbSnF4 solid electrolyte in high temperature region. Measured value is 2×10-10 (m2/s) at 300 °C. This value is in good agreement with the experimental results of conductivity and NMR T1 relaxation time.
Sodium gluconate (SG) and potassium gluconate (PG) were tested as an electrolyte additive for the prevention of dendrite formation. The obtained results of the zinc electrode have been investigated using cyclic voltammetry (CV) and scanning electron microscopy (SEM) studies. CV was carried out in 7 M KOH + 0.2 M ZnO with and without the addition of 5 mM additives, and then, Zn working electrode was observed by SEM. Importantly, the experimental results of CV and SEM show that the additives of SG and PG can bring a reversible behavior of 300 cycles of CVs at the potential range of 100 mV from open circuit potential and a significant improvement in surface Zn morphology and result in the reduction of dendritic growth. We have focused on OH ions which are important species of Zn anode reactions. Firstly, we check the possibility of the observation of OH ions in Raman Spectra. Raman line of OH ions at 3600 cm-1 are strongly dependent on the concentration of KOH. Subsequently, we have taken in situ Raman spectra for composite Zn electrode. Raman lines of the electrode components of ZnO, PTFE and acetylene black were clearly observed on in situ Raman spectrum at OCP. This in situ Raman spectrum at OCP directs to the variation of Raman spectra at various potentials.
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