• Korean Chemical Engineering Research
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• v.56 no.3
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• pp.320-326
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• 2018

In this study, Graphite/Silicon/Carbon (G/Si/C) composites were synthesized to improve the electrochemical properties of Graphite as an anode material of lithium ion battery. The prepared G/Si/C composites were analyzed by XRD, TGA and SEM. Also the electrochemical performances of G/Si/C composites as the anode were performed by constant current charge/discharge, rate performance, cyclic voltammetry and impedance tests in the electrolyte of $LiPF_6$ dissolved inorganic solvents (EC:DMC:EMC=1:1:1 vol%). Lithium ion battery using G/Si/C electrode showed better characteristics than graphite electrode. It was confirmed that as the silicon content increased, the capacity increased but the capacity retention ratio decreased. Also, it was shown that both the capacity and the rate performances were improved when using the Silicon (${\leq}25{\mu}m$). It is found that in the case of 10 wt% of Silicon (${\leq}25{\mu}m$), G/Si/C composites have the initial discharge capacity of 495 mAh/g, the capacity retention ratio of 89% and the retention rate capability of 80% in 2 C/0.1 C.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.439-445
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• 2022

In this study, Silicon and petroleum pitch were coated on the surface of Si/C fiber manufactured using electrospinning to improve the electrochemical performances. SiO₂/PAN fiber was prepared by electrospinning with TEOS and PAN at various ratios dissolved in DMF. The characteristics of carbonization, reduction, and pitch coating processes were investigated for the optimal process of the pitch coated Si/C fiber anode composite. Anode composite prepared with TEOS/PAN = 4/6 (CR-46) after carbonization and reduction process has a capacity of 657 mAh/g. To improve capacity and stability, Si powder and PFO pitch were coated at the surface of CR-46. When the pitch composition was fixed at 10 wt%, it was found that the capacity increased as the weight ratio of silicon increased, but the stability decreased. The pitch coated Si/C fiber composite with 10 wt% silicon has high capacity of 982.4 mAh/g and capacity retention of 86.1%. In the test to evaluate rate performance, the rate capability was 80.2% (5C/0.1C).

• Proceedings of the Materials Research Society of Korea Conference
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• 2003.03a
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• pp.151-151
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• 2003

최근 휴대폰용 LCD, 컴퓨터용 TFT LCD, 가정용 PDP 등 평판 디스플레이 산업의 발달에 힘입어 평판 디스플레이 장치의 구동 칩 실장 부품인 TCP(tape carrier package), COF(chip on film) 제조 산업 또한 발전하고 있다. 이들 TCP, COF는 디스플레이 장치의 경박화에 따라 보다 가는 선폭의 회로가 요구되어지는데 이를 위해 회로를 구성하는 기본소재로 얇은 두께의 동박이 사용된다. 회로기판용 동박으로는 압연동박과 전해동박이 함께 사용되어 왔으나 박막의 제조가 어려운 압연동박의 단점과 면에 수직한 주상정 조직이 발달해 있어 일반 압연 동박에 비해 접착력이 뛰어나며 전류밀도 또는 티타늄 음극 드럼 회전 속도를 조절하여 두게 조절이 용이한 전해동박의 장점으로 인해 현재 압연동박의 전해동박으로의 대체가 증가하고 있다. 전해동박의 제조공정은 크게 제박 공정과 후처리 공정으로 나눌 수 있다. 전해동박은 먼저 드럼형태의 티타늄 음극과 불용성 납 양극으로 이루어진 제박기에 고 전류를 가하여 황산구리 용액 중 구리를 티타늄 음극에 석출시킴으로서 구리 원박을 제조한 후 접착력 향상을 위한 노듈 형성, 방식, 방청, 내열성 향상 등을 위한 여러 개의 단위 셀 조합으로 이루어진 후처리 공정을 거쳐 제조된다.

• Journal of Adhesion and Interface
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• v.24 no.1
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• pp.9-16
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• 2023

Silicon has been studied as an anode material for next-generation lithium ion batteries due to its high theoretical electrochemical capacity. However, the extreme volume change during the lithiation/delithiation and the inherently low electronic conductivity of silicon hamper the practical application of silicon anodes. Conductive polymer binders are effective means to solve these problems, and it has been reported that the performance of the silicon anode can be greatly improved through the proper molecular design of the conductive polymer binders. In this paper, representative recent studies on conductive polymer binders for silicon anodes will be introduced, and through this, binder design strategies to overcome the limitations of silicon anodes will be explored.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.213-214
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• 2023

The burden of housing heating costs has increased as energy prices such as global oil prices (28.1%), LNG (38%) and minerals (100%) have soared due to the Ukraine crisis. Accordingly, an electrically conductive cement composites had developed using waste carbon materials such as waste cathode materials, waste CNTs, and waste carbon fibers, and the heat generation performance was evaluated.

• Clean Technology
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• v.29 no.3
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• pp.178-184
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• 2023

Transition metal chalcogenides have garnered significant attention as anode materials for sodium-ion batteries due to their high theoretical capacity. Nevertheless, their practical application is impeded by their limited lifespan resulting from substantial volume expansion during cycling and their low electrical conductivity. To tackle these issues, this study devised a solution by synthesizing a nanostructured anode material composed of porous CNT (carbon nanotube) spheres and (Ni,Co)Se₂ nanocrystals. By employing spray pyrolysis and subsequent heat treatments, a porous-structured (Ni,Co)Se₂-CNT composite microsphere was successfully synthesized, and its electrochemical properties as an anode for sodium-ion batteries were evaluated. The synthesized (Ni,Co)Se₂-CNT microsphere possesses a porous structure due to the nanovoids that formed as a result of the decomposition of the polystyrene (PS) nanobeads during spray pyrolysis. This porous structure can effectively accommodate the volume expansion that occurs during repeated cycling, while the CNT scaffold enhances electronic conductivity. Consequently, the (Ni,Co)Se₂-CNT anode exhibited an initial discharge capacity of 698 mA h g^-1 and maintained a high discharge capacity of 400 mA h g^-1 after 100 cycles at a current density of 0.2 A g^-1.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.607-612
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• 2021

Silicon (Si) is one of the promising active materials to replace the widely used graphite because of its low electrochemical potential and high theoretical capacity. However, Si anodes still face in problems with the huge volume expansion and continuous decomposition of the electrolyte during repeated charge and discharge processes. To address these issues, a cross-linkable waterborne polyurethane (CWPU) based on a bio-oil, castor oil, was prepared and reacted with Tris(2,3-epoxypropyl) isocyanurate (TGIC) linkers, resulting in the formation of a mechanically robust 3D network structure. Si anodes fabricated with the CWPU-TGIC exhibited stable cycling performances and excellent discharge capacities. The results revealed that the CWPU-TGIC binder efficiently accommodates the large volume change for Si anode during charge and discharge cycles. Overall, the eco-friendly binder shows great promise in improving the electrochemical performances of Si anodes.

• Journal of the Korean Electrochemical Society
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• v.21 no.3
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• pp.55-60
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• 2018

The demand for LIBs with higher energy densities has increased continuously because the emergence of wider and more challenging applications including HEV and EV has became imperative. However, in the case of anode material, graphite is insufficient to meet this need. To meet such demand, several type of negative electrode materials like silicon, tin, SiO, and transition metal oxide have been investigated for the advanced lithium secondary batteries. Recently, lithium vanadium oxide, which has a layered structure, is assumed as one of the promising anode material as alternative of graphite. This material shows a high volumetric capacity, which is 1.5 times higher than that of graphite. However, relative low electrical conductivity and particle fracture, which results in the electrolyte decomposition and loss of electric contact between electrode, induce rapid capacity decay. In this report, we investigated the effect of electrolyte additive on the electrochemical characteristics of lithium vanadium oxide.

• Applied Chemistry for Engineering
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• v.26 no.1
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• pp.80-85
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• 2015

Silicon/carbon composites as anode materials for lithium-ion batteries were examined to find the cycle performance and capacity. Silicon/carbon composites were prepared by a two-step method, including the magnesiothermic reduction of SBA-15 (Santa Barbara Amorphous material No. 15) and carbonization of phenol resin. The electrochemical behaviors of lithium ion batteries were characterized by charge/discharge, cycle, cyclic voltammetry and impedance tests. The improved electrochemical performance attributed to the fact that silicon/carbon composites suppress the volume expansion of the silicon particles and enhance the conductivity of silicon/carbon composites (30 ohm) compared to that of using the pure silicon (235 ohm). The anode electrode of silicon/carbon composites showed the high capacity approaching 1,348 mAh/g and the capacity retention ratio of 76% after 50 cycles.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.203-209
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• 2023

Cobalt sulfide nanocomposites were synthesized through a simple hydrothermal method as anode materials for sodium ion batteries (SIBs). In this work, a cobalt sulfide nanoparticle (CoS-NF) and a cobalt sulfide nanocomposite integrated with reduced graphene oxide (CoS@G-NC) were fabricated for electrochemical energy storage performance of battery. The as-prepared CoS@G-NC electrode exhibited reversible and stable cycle performance (62 % after 30 cycles at current density of 200 mA g^-1). The improved electrochemical property was attributed to the small grain growth and uniform distribution of cobalt sulfide during synthesis, which maximized the diffusion pathway for sodium ions and effectively suppressed the delamination and volume expansion of cobalt sulfide during the conversion reaction. The results provide promising anode materials for next-generation SIBs.