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Song, Hakhyeon,Im, Mintaek,Song, Jun Tae,Lim, Jung-Ae,Kim, Beom-Sik,Kwon, Youngkook,Ryu, Sangwoo,Oh, Jihun Elsevier 2018 Applied Catalysis B Vol.232 No.-
<P><B>Abstract</B></P> <P>Mass transfer, kinetics, and mechanism of electrochemical CO<SUB>2</SUB> reduction have been explored on a model mesostructure of highly-ordered copper inverse opal (Cu-IO), which was fabricated by Cu electrodeposition in a hexagonally-closed packed polystyrene template. As the number of Cu-IO layers increases, the formation of C<SUB>2</SUB> products such as C<SUB>2</SUB>H<SUB>4</SUB> and C<SUB>2</SUB>H<SUB>5</SUB>OH was significantly enhanced at reduced overpotentials (∼200 mV) compared to a planar Cu electrode. At the thickest layer, we observe for the first time the formation of acetylene (C<SUB>2</SUB>H<SUB>2</SUB>), which can be generated through a kinetically slow reaction pathway and be a key descriptor in the unveiling of the CC coupling reaction mechanism. Based on our experimental observation, a plausible reaction pathway in Cu mesostructures is rationalized.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ordered Cu-mesostructures for electrochemical CO<SUB>2</SUB> reduction. </LI> <LI> Mass transfer, kinetics and mechanisms of CO<SUB>2</SUB> reduction are suggested. </LI> <LI> Mesoporous-dependent C<SUB>1</SUB> and C<SUB>2</SUB> products formation. </LI> <LI> Acetylene is observed for the first time from electrochemical CO<SUB>2</SUB> reduction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Song, Jihun,Shin, Dong Ok,Byun, Seoungwoo,Roh, Youngjoon,Bak, Cheol,Song, Juhye,Choi, Jaecheol,Lee, Hongkyung,Kwon, Tae-Soon,Lee, Young-Gi,Ryou, Myung-Hyun,Lee, Yong Min The Korean Electrochemical Society 2022 Journal of electrochemical science and technology Vol.13 No.2
The microblade cutting method, so-called SAICAS, is widely used to quantify the adhesion of battery composite electrodes at different depths. However, as the electrode thickness or loading increases, the reliability of adhesion values measured by the conventional method is being called into question more frequently. Thus, herein, a few underestimated parameters, such as friction, deformation energy, side-area effect, and actual peeing area, are carefully revisited with ultrathick composite electrodes of 135 ㎛ (6 mAh cm<sup>-2</sup>). Among them, the existence of side areas and the change in actual peeling area are found to have a significant influence on measured horizontal forces. Thus, especially for ultrahigh electrodes, we can devise a new SAICAS measurement standard: 1) the side-area should be precut and 2) the same actual peeling area must be secured for obtaining reliable adhesion at different depths. This guideline will practically help design more robust composite electrodes for high-energy-density batteries.
3D electrochemical model for a Single Secondary Particle and its application for operando analysis
Song, Jihun,Park, Joonam,Appiah, Williams A.,Kim, Sung-Soo,Munakata, Hirokazu,Kanamura, Kiyoshi,Ryou, Myung-Hyun,Lee, Yong Min Elsevier 2019 Nano energy Vol.62 No.-
<P><B>Abstract</B></P> <P>We developed a 3D electrochemical model for simulating the electrochemical properties and revealing the internal properties of a single LiFePO<SUB>4</SUB> secondary particle during cycling. The main model parameters, such as the diffusion coefficient and rate constant, were optimized using rate capability data, which have been measured experimentally with a unique single particle measurement technique. We simulated voltage profiles at different c-rates from 2 to 20C, which were approximately equivalent to the experimental voltage profiles. The model estimated real-time overpotential, lithium ion concentration, and state-of-charge within the single particle, which have not been obtained experimentally, while changing design parameters and operating conditions. We validated the reliability and applicability of the model by comparing and analyzing the electrochemical results of various LiFePO<SUB>4</SUB> secondary particles with variable design parameters (i.e., solid volume fraction, secondary particle size, and primary particle size).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A single LiFePO<SUB>4</SUB> secondary particle shows high capacity retention at high C-rate. </LI> <LI> The particle was modeled with reflecting the experimental conditions. </LI> <LI> Performance can be easily predicted by different design parameters using simulation tool. </LI> <LI> Internal properties of a single particle were observed, which cannot be measured by experimental methods. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>This graphics illustrates a 24 μm LiFePO4 secondary particle consisting of millions of primary particles of 100–200 nm in diameter. We propose a 3D electrochemical model for simulating the electrochemical properties and unveiling the internal properties of the single particle while changing both particle design parameters and operating conditions.</P> <P>[DISPLAY OMISSION]</P>