In this study, polyimide (PI)-based activated carbon fibers (ACFs) were prepared for application as electrode materials in electric double-layer capacitors by varying the steam activation time for the PI fiber prepared under identical cross-linking conditions. The surface morphology and microcrystal structural characteristics of the prepared PI-ACFs were observed by field-emission scanning electron microscopy and X-ray diffractometry, respectively. The textural properties (specific surface area, pore volume, and pore size distribution) of the ACFs were calculated using the Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, and non-local density functional theory equations based on N2/ 77 K adsorption isotherm curve measurements. From the results, the specific surface area and total pore volume of PI-ACFs were determined to be 760–1550 m2/ g and 0.36–1.03 cm3/ g, respectively. It was confirmed that the specific surface area and total pore volume tended to continuously increase with the activation time. As for the electrochemical properties of PI-ACFs, the specific capacitance increased from 9.96 to 78.64 F/g owing to the developed specific surface area as the activation time increased.

The waste secondary battery contains a significant amount of valuable metals, making its recycling highly desirable. However, conventional chemical methods for recycling are environmentally unfriendly and cost-ineffective. Rather than the chemical method, this paper deals with a mechanical method for recovering electrode materials from waste secondary batteries by blowing pressurized air onto the interface area between the electrode and the separator. Especially, in this study, the effective blowing angle were searched by simulating the separation of the electrode material from the separator through 1-way fluid structure interaction analysis based on the Cohesive Zone Modeling technique.

Graphitic carbon nitride (g-C3N4) has attracted extensive attention in energy storage due to its suitable and tunable bandgap, high chemical/thermal stability, earth abundance and environmental friendliness. However, its conductivity should be improved to work as the electrode materials in supercapacitors. In this report, we have prepared a two-dimensional composite (CN-PANI) based on g-C3N4 and polyaniline (PANI) by in-situ polymerization, which can be efficiently applied as electrode material for supercapacitors. The introduction of PANI can increase the conductivity of the electrode, and the porous structure of g-C3N4 can provide enough channels for the transport of electrolyte ions and improve the electrode stability. As a result, the obtained CN-PANI demonstrates excellent specific capacitance (234.0 F g− 1 at 5 mV/s), good rate performance and high cycling stability (86.2% after 10,000 cycles at 50 mV/s), showing great potential for high-rate supercapacitors.

In this study, we developed a facile and template-free strategy for the preparation of activated porous carbon beads (APCBs) from polyacrylonitrile. The chemical activation with KOH was found to enhance the pore properties, such as specific surface area (SSA), pore volume, and pore area. The APCBs exhibited a large SSA of 1147.99 m2/g and a pore area of 131.73 m2/g. The APCB-based electrodes showed a good specific capacitance of 112 F/g at 1 A/g in a 6 M KOH electrolyte, and excellent capacitance retention of 100% at a current density of 5 A/g after 1000 cycles. Therefore, the APCBs prepared in this study can be applied as electrode materials for electric double-layer capacitors.

The porous carbons with high specific surface area and excellent electrochemical properties were prepared using three types of green needle coke as raw materials. Electrochemical performances of the porous carbons derived from different microstructure green needle coke were investigated. The XRD and Raman spectra demonstrated that the content of the ordered carbon microcrystals were decreased and the content of amorphous and cross-linked structure were increased in the porous carbons with comparison to the raw materials. The results of N2 adsorption–desorption analysis verified that the content of ordered microcrystalline structure in the raw materials evidently influence the specific surface area and pore size distribution of the porous carbons. The porous carbon with 1665 m2 g−1 specific surface area and 2.89 nm average pore size has shown that the specific capacitance was 288 F g−1 at the current density 1 A g−1. Furthermore, the capacity retention was 94.93% and the Coulombic efficiency was 92.87% after 5000 charge/discharge cycles.

Necessity of novel energy storage devices extensively increased due to consumption of high power in various devices. To address the issues, in this report, we are addressing with a composite Iron Sulfide/reduced Graphene Oxide ( Fe3S4/rGO) synthesized using the standard solvothermal method. X-ray diffraction and Field Emission Scanning Electron Microscope analysis results confirmed that Face-Centered cubic crystal structure of Fe3S4 and rGO’s surface is decorated with a mean diameter of < 50 nm Fe3S4 respectively. Transmission Electron Microscopy images show further evidence that dispersed Fe3S4 on the rGO surface. Fe3S4/ rGO exhibits specific capacitance of 560 F/g than its individual counterparts ( Fe3S4 = 200 F/g and rGO = 145 F/g) at 1 A/g of current density and maximum cyclic stability of 91% capacitance retention after 2000 cycles that may be the influence of synergy between the composite materials.

Sustainable biomass-derived porous carbons demonstrate excellent capacitive properties owing to their heteroatom-rich nature and distinct textural feature. Herein, a series of nitrogen-/phosphorus-/oxygen-containing microporous carbons (CWWN/ P/O-MPCs) have been successfully fabricated by etching in H2O2 solution, pre-treatment of camphor wood wastes with KOH solution and subsequent carbonization. As an electrode material for supercapacitors, the typical microporous carbon (CWW-N/P/O-MPCs-0.5) exhibits a remarkably high specific capacitance of 245 F g− 1 at 0.5 A g− 1, corresponding to an impressively large volumetric capacitance of 208 F m− 3, and excellent long-term stability over 10,000 cycles. The excellent electrochemical performance can be ascribed to the optimal combination of heteroatom groups and ultrafine micropores.

Graphene is a single atomic layer of carbon atoms, and has exceptional electrical, mechanical, and optical characteristics. It has been broadly utilized in the fields of material science, physics, chemistry, device fabrication, information, and biology. In this review paper, we briefly investigate the ideas, structure, characteristics, and fabrication techniques for graphene applications in lithium ion batteries (LIBs). In LIBs, a constant three-dimensional (3D) conductive system can adequately enhance the transportation of electrons and ions of the electrode material. The use of 3D graphene and graphene-expansion electrode materials can significantly upgrade LIBs characteristics to give higher electric conductivity, greater capacity, and good stability. This review demonstrates several recent advances in graphenecontaining LIB electrode materials, and addresses probable trends into the future.

The design and fabrication of photoelectrochemical (PEC) electrodes for efficient water splitting is important for developing a sustainable hydrogen evolution system. Among various development approaches for PEC electrodes, the chemical vapor deposition method of atomic layer deposition (ALD), based on self-limiting surface reactions, has attracted attention because it allows precise thickness and composition control as well as conformal coating on various substrates. In this study, recent research progress in improving PEC performance using ALD coating methods is discussed, including 3D and heterojunction-structured PEC electrodes, ALD coatings of noble metals, and the use of sulfide materials as co-catalysts. The enhanced long-term stability of PEC cells by ALD-deposited protecting layers is also reviewed. ALD provides multiple routes to develop improved hydrogen evolution PEC cells.

Transparent conducting electrodes (TCEs) are attracting considerable attention as an important component for emerging optoelectronic applications such as liquid crystal displays, touch panels, and solar cells owing to their attractive combination of low resistivity (< 10-3 Ω cm) and high transparency (>80%) in the visible region. The solutionbased process has unique properties of an easy fabrication procedure, scalability, and low cost compared to the conventional vacuum-based process and may prove to be a useful process for fabricating TCEs for future optoelectronic applications demanding large scale and flexibility. In this paper, we focus on the introduction of a solution-based process for TCEs. In addition, we consider the powder materials used to fabricate solution-based TCEs and strategies to improve their transparent conducting properties.

Activated carbons (ACs) were prepared by activation of coal tar pitch (CTP) in the range of 700°C-1000°C for 1-4 h using potassium hydroxide (KOH) powder as the activation agent. The optimal activation conditions were determined to be a CTP/KOH ratio of 1:4, activation temperature of 900°C, and activation time of 3 h. The obtained ACs showed increased pore size distribution in the range of 1 to 2 nm and the highest specific capacitance of 122 F/g in a two-electrode system with an organic electrolyte, as measured by a charge-discharge method in the voltage range of 0-2.7 V. In order to improve the performance of the electric double-layer capacitor electrode, various mixtures of CTP and petroleum pitch (PP) were activated at the optimal activation conditions previously determined for CTP. Although the specific capacitance of AC electrodes prepared from CTP only and the mixtures of CTP and PP was not significantly different at a current density of 1 A/g, the AC electrodes from CTP and PP mixtures showed outstanding specific capacitance at higher current rates. In particular, CTP-PP61 (6:1 mixture) had the highest specific capacitance of 132 F/g, and the specific capacitance remained above 90% at a high current density of 3 A/g. It was found that the high specific capacitance could be attributed to the increased micro-pore volume of ACs with pore sizes from 1 to 2 nm, and the high power density could be attributed to the increased meso-pore volume.

Commercial activated-carbon used as the electrode material of an electric double-layer capacitor (EDLC) was posttreated with various acids and alkalis to increase its capacitance. The carbon samples prepared were then heat-treated in order to control the amount of acidic functional groups formed by the acid treatments. Coin-type EDLC cells with two symmetric carbon electrodes were assembled using the prepared carbon materials and an organic electrolyte. The electrochemical performance of the EDLC was measured by galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy. Among the various activated carbons, the carbon electrodes (CSsb800) prepared by the treatments of coconutshell-based carbon activated with NaOH and H3BO5, and then heat treated at 800˚C under a flow of nitrogen gas, showed relatively good electrochemical performance. Although the specific-surface-area of the carbon-electrode material (1,096m2/g) was less than that of pristine activated-carbon (1,122m2/g), the meso-pore volume increased after the combined chemical and heat treatments. The specific capacitance of the EDLC increased from 59.6 to 74.8 F/g (26%) after those post treatments. The equivalent series resistance of EDLC using CSsb800 as electrode was much lower than that of EDLC using pristine activated carbon. Therefore, CSsb800 exhibited superior electrochemical performance at high scan rates due to its low internal resistance.

Odorous compounds produced from blackwater commonly cause domestic nuisance complaints. In this study, aseries of experiments was conducted to apply an electrolytic oxidation system to abate the odor problems fromblackwater. The electrolytic process removes odorous compounds from the liquid sources using direct and indirectoxidation; therefore, the system performance mainly relies on electrode materials. Four different electrodematerials, SS304, SS316, Ti, Ti/IrO₂, were applied, and the electrolytic oxidation showed that hydrogen sulfideand organic constituents were effectively removed. However, the weights of electrodes, SS304 and SS316, weredecreased by 7.5~8% due to the electrochemical decomposition from the anode surface. In order to improve thedurability and economical feasibility, SS304 was used as the cathode while Ti/IrO₂ was used as the anode. Theelectrode combination with the different materials (Ti/IrO₂:SS304) showed the same odor removal efficiency asthat using the same material (Ti/IrO₂:Ti/IrO₂). Consequentially, the electrolytic reaction to oxidize odorous andorganic constituents in humane manure was strongly affected by the electrode materials, and its combination needsto be carefully selected to achieve better performance.

Powder library of pseudo four components Li-Ni-Co-Ti compounds were prepared for exploring the composition region with the single phase of the layer-type structure by using combinatorial high-throuput preparation system "M-ist Combi" based on electrostatic spray deposition method. The new layer-type compounds were found wider composition region than the previous report. This process is promising way to find multi component functional materials.

50/50 vol% LSM-YSZ의 복합공기극(LSM=La1-xSrxMnO3(0≤x≤0.5))이 콜로이드 증착법에 의해 준비으며 주사전자현미경과 임피던스 분석기에 의해 연구되어졌다. 재현성있는 임피던스 스펙트럼들이 LSM-YSZ/YSZ/LSM-YSZ로 구성된 향상된 셀을 사용함으로써 얻어졌다. 이러한 셀들의 임피던스 스펙트럼들은 작동온도에 강하게 영향을 받았으며, 가장 안정된 조건은 900˚C에서 도달되어졌다. 900˚C에서 공기//공기 셀에 대해 측정된 전형적인 임피던스 스펙트럼들은 2개의 불완전한 호(depressed arc)로 구성되었다. LSM전극에 대한 YSZ의 첨가는 LSM-YSZ 공기극의 저항 감소를 가져왔으며, 전해질 표면의 불순물의 영향을 제거하기 위한 연마는 공기극 저항을 더욱 감소시켰다. 또한 촉매층(Ni 혹은 Sr)을 가진 LSM-YSZ 전극은 촉매층이 없는 경우에 비해 공기극 저항의 감소를 가져왔다. LSM-YSZ 공기극 저항은 전극조성, 전해질의 형태, 인가 전류에 의해 영향을 받았다.

강유전체 재료의 하부전극으로 사용되고 있는 Pt/Ti 박막의 접착력에 대한 열처리 분위기의 영향을 연구하였다. 시편의 접착력은 90˚ 필 테스트 방법을 사용하여 정량적으로 측정하였다. 열처리 후 사용된 분이기에 관계없이 모두 접착력이 감소하였는데 특히 산소분위기에서 열처리 한 시편의 접착력이 매우 크게 감소하였다. AES depth profile과 단면 TEM을 이용하여 계면반응을 관찰한 결과 산소열처리시에는 Ti가 외부에서 확산해 온 산소와 반응하여 rutile TiO2상이 형성됨을 알 수 있었다. 그러므로 산소열처리 후에 일어나는 접착력의 급격한 감소 원인은 열처리시 취약한 TiO2상이 형성되며 이로 인해 Ti 접착층이 고갈되기 때문임을 알 수 있었다.

Ta2O5 박막은 실리콘산화막, 실리콘질화막 박막에 비해 유전율은 높으나 누설전류밀도가 높고, 절연파괴강도가 낮아 DRAM의 커패시터용 재료로서 실용화가 되지 못하고 있다. 본 연구에서는 LPCVD법으로 형성시킨 300Å 두께의 Ta2O5 유전체박막에 대해 후속열처리 또는 전극재료를 변화시켜 열악한 전기적 특성의 원인을 규명하고자 하였다. 그 결과 다결정 실리콘 전극의 경우 성막상태의 Ta2O5 박막은 전극에 의한 환원반응에 의해 전기적 특성이 열화됨을 알 수 있었고, 이를 TiN 전극의 사용으로 억제시킬 수 있었다. 다결정 실리콘 전극의 경우 성막상태의 Ta2O5 유전체는 누설정류밀도가 10-1A/cm2, 절연파괴강도가 1.5MV/cm 정도였으며, 800˚C에서 O2열처리를 하면 전기적 특성은 개선되나, 유전율이 낮아진다 TiN 전극을 채용할 경우 누설전류밀도 10-6~10-7A/cm2, 절연파괴강도 7~12MV/cm 로 ONO(Oxide-Nitride-Oxide) 박막과 비슷한 Ta2O5 고유전막을 얻을 수 있었다.