• Journal of Industrial and Engineering Chemistry
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• v.68
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• pp.140-145
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• 2018

Bulky carbon layer uniformly distributed with nanoscale $Fe_2O_3$ was prepared via a direct carbonation of $Fe^{3+}$-polyacrylonitrile complexes at $700^{\circ}C$ under $N_2$ flow. The iron oxide carbon composites exhibited an excellent cycling performance for lithium storage with a reversible capacity of ${\sim}810mAh\;g^{-1}$ after 250 cycles at a current rate of $100mA\;g^{-1}$. The enhancement was mainly attributed to dual functions of bulky carbon layer which facilitated the lithium-ion diffusion and accommodated the volume changes of active $Fe_2O_3$ during charge/discharge process. Our novel chemical strategy is quite effective for scalable fabrication of high capacity lithium-storage materials.

• Journal of Powder Materials
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• v.23 no.4
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• pp.317-324
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• 2016

Tin is one of the most promising anode materials for next-generation lithium-ion batteries with a high energy density. However, the commercialization of tin-based anodes is still hindered due to the large volume change (over 260%) upon lithiation/delithiation cycling. To solve the problem, many efforts have been focused on enhancing structural stability of tin particles in electrodes. In this work, we synthesize tin nano-powders with an amorphous carbon layer on the surface and surroundings of the powder by electrical wire explosion in alcohol-based liquid media at room temperature. The morphology and microstructures of the powders are characterized by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. The electrochemical properties of the powder for use as an anode material for lithium-ion battery are evaluated by cyclic voltammetry and a galvanometric discharge-charge method. It is shown that the carbon-coated tin nano-powders prepared in hexanol media exhibit a high initial charge specific capacity of 902 mAh/g and a high capacity retention of 89% after 50 cycles.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.131-138
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• 2019

To improve the performance of Si anodes in advanced Li-ion batteries, the design of the electrode plays a critical role, especially due to the large volumetric expansion in the Si anode during Li insertion. In our study, we used a simple fabrication method to prepare Si-based electrodes by grafting polyacrylic acid (PAA) to a carboxymethyl cellulose (CMC) binder (CMC-g-PAA). The procedure consists of first mixing nano-sized Si and the binders (CMC and PAA), and then coating the slurry on a Cu foil. The carbon network was formed via carbonization of the binders i.e., by a simple heat treatment of the electrode. The carbon network in the electrode is mechanically and electrically robust, which leads to higher electrical conductivity and better mechanical property. This explains its long cycle performance without the addition of a conducting agent (for example, carbon). Therefore, the partially carbonized CMC-g-PAA binder presented in this study represents a new feasible approach to produce Si anodes for use in advanced Li-ion batteries.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.36 no.1
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• pp.29-35
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• 2023

Herein we investigated the effect of the conductive agent on the electrochemical performance of the SiOx anode. SiOx anodes have a relatively low volume expansion (~160%) compared to Pure-silicon, but have a problem in that they have a poor electrical conductivity characteristic. In this study, physical and electrochemical measurements were performed using two 0-dimensional amorphous carbon conductive agents with different crystallinity and surface area. The crystal structure of the conductive agents and the local graphitization degree were analyzed through XRD and Raman, and the surface area of the particles was observed through BET. In addition, the electrical performance according to the graphitization degree of the conductive agents was confirmed through a 4-point probe. As a result of the electrochemical cycle and rate performance, it was confirmed that the performance of SiOx using a conductive agent having a low graphitization degree and a high surface area was improved. The results in this study suggest that the graphitization degree and surface area of the amorphous carbon conductive agent may play an important role in the SiOx electrode.

• Carbon letters
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• v.2 no.1
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• pp.72-75
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• 2001

The performance of Li-ion system based on $LiCoO_2$ and Graphite is well optimized for the 3C applications. The charge-discharge mode, the manufacturing process, the cell performance and the thermal reactions affecting safety has been explained in the engineering point of view. The energy density of the current LIB system is in the range of 300~400 Wh/l. In order to achieve the energy density higher than 500 Wh/l, the active materials should be modified or changed. Adopting new high capacity anode materials would be effective to improve energy density.

• Bulletin of the Korean Chemical Society
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• v.35 no.1
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• pp.257-260
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• 2014

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.307-312
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• 2017

In this study, the electrochemical performance of surface modified carbon using the PFO (pyrolyzed fuel oil) was investigated by chemical activation with KOH and $K_2CO_3$. PFO was heat treated at $390{\sim}400^{\circ}C$ for 1~3h to prepared the pitch. Three carbon precursors (pitch) prepared by the thermal reaction were 3903 (at $390^{\circ}C$ for 3h), 4001(at $400^{\circ}C$ for 1h) and 4002 (at $400^{\circ}C$ for 2h). Also, the effect of chemical activation catalysts and mixing time on the development of porosity during carbonization was investigated. The prepared carbon was analyzed by BET and FE-SEM. It was shown that chemical activation with KOH could be successfully used to develop carbon with specific surface area ($3.12m^2/g$) and mean pore size (22 nm). The electrochemical characteristics of modified carbon as the anode were investigated by constant current charge/discharge, cyclic voltammetry and electrochemical impedance tests. The coin cell using pitch (4002) modified by KOH has better initial capacity (318 mAh/g) than that of other pitch coin cells. Also, this prepared carbon anode appeared a high initial efficiency of 80% and the retention rate capability of 2C/0.1 C was 92%. It is found that modified carbon anode showed improved cycling and rate capacity performance.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.11
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• pp.757-764
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• 2012

The surface of graphite fiber fabric anode was modified with a hydrogel and a mixture of hydrogel and multiwall carbon nanotube, and their effectiveness were compared to the unmodified anodes in a batch microbial fuel cell (microbial fuel cells). The maximum power density of the MFC was determined by both performance of the anode and cathode. The maximum power density for the MFC with the anode modified with the mixture of hydrogel and multiwall carbon nanotube was $1,162mW/m^2$ which was 27.7% higher than that with the unmodified graphite fiber fabric anode. "The mixture of hydrogel and multiwall carbon nanotube is a good surface modifier for anode with high biological affinity and low activation losses."

• Korean Chemical Engineering Research
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• v.56 no.6
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• pp.798-803
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• 2018

In order to use Si as an anode material for lithium-ion battery, the particle size was controlled to less than $0.5{\mu}m$ and carbon was coated on the surface with the thickness less than 10 nm. The carbon fiber was grown on the Si surface with 50~150 wt%, and the carbon coating was carried out once again. The Si composite material was mixed with dissimilar metals to increase the conductivity, and graphite was mixed to improve cyclic life characteristics. The physical and electrochemical characteristics of composite materials were measured with XRD, SEM, TEM and coin cell. The discharge capacity of Si/PC/CNF/PC was lower than that of Si/PC (Pyrolytic Carbon)/CNF (Carbon Nano Fiber). However, the cyclic life of Si/PC/CNF/PC was higher. Initial discharge capacity of 1512 mA h g-1 at 0.2 C rate and initial efficiency of 78% were shown. It also showed a capacity retention of 94% in 10 cycles.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.9-12
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• 2008

The internal reforming of n-Butane on Ni-YSZ and Cu-Ceria-YSZ was investigated with anode granule at steam to carbon ratio from 0 to 3 and at temperature of $750^{\circ}C$. Although hydrogen production was lager at Ni-YSZ, resistivity for carbon deposition was better at Cu-Ceria-YSZ. These phenomena occur because unwanted side reaction go on with reforming reaction for hydrogen production at Ni-YSZ.