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This study demonstrates the increased integrity of graphite–SiOx–C hierarchical structure using 3-aminopropyltrimethoxysilane (APS). Furthermore, the carbon coating contributes to elec-trode stability.

Artificial graphites have been used in various applications, for example, as anode materials for Li-ion batteries, C/C composites, and electrodes for aluminum smelting, due to their unique mechanical strength and high thermal and electrical conductivity. Artificial graphites can be manufactured by a series of kneading, molding, carbonization and graphitization processes with an additional impregnation process. In this study, the influence of the process variables in the kneading and carbonization/graphitization process on the properties of the resulting carbon block was systemically investigated. During the kneading process, the optimum kneading temperature was 90 °C higher than the softening point of the binder pitch; thus, the binder pitch reached its maximum fluidity. On the other hand, during the carbonization and graphitization process, the structural properties of carbon blocks prepared at different heat treatment temperatures were examined and their structural change and evolution were closely described according to the temperature and divided into low-temperature carbonization and high-temperature carbonization/graphitization. Based on this study, we expect to provide a better understanding of setting the parameters for thermally conductive carbon block manufacturing.

A solid electrolyte interphase (SEI) on an anode is a critical issue in lithium-ion batteries because it is related to cycling stability. In this study, we introduce a semi-ionic C F bond on the surface of graphite (SICF) via plasma fluorination to introduce a LiF-based SEI layer on the anode during the first cycle. In the charge-discharge profiles and cyclic voltammetry curves, a peak related to the LiF-based SEI formation was clearly observed for SICF. In particular, SICF had an excellent long-term cycling stability of 98.8% for 100 cycles (1.0 C-rate). From the anodes of the disassembled coin cells, it was found that semi-ionic C F bonds improved the formation of a stable LiF-based SEI layer and decreased the number of side reactions with HF, which was produced from PF5. Moreover, SICF exhibited a lower volume expansion compared to that of the pristine anode and the anode with covalent C F bonds. Therefore, introducing a semi-ionic C F bond via plasma fluorination is a key strategy for forming a LiF-based SEI layer on the graphite anode surface that enhances the cycling stability of lithium-ion batteries.

In this study, Needle and Regular coke, which has different crystalline and orientation characteristics, were graphitized, and the effect of crystal changes on electrochemical performance was investigated. The initial efficiency and capacity were mainly influenced by the shapes and specific surface areas of the particles, and the graphitized sample showed excellent initial efficiency due to having a lower specific surface area (decrease in exposed edge surfaces) than the coke. However, rate performance shows excellent in the graphitized sample of regular coke due to its defects and short lithium-ion transport path.

This study examined the effects of micro- (crystallinity) and macro (orientation)-crystalline properties of graphite on the initial efficiency, discharge capacity, and rate performance of anodic materials. Needle coke and regular coke were selected as raw materials and pulverized to 2–25 μm to determine the effects of crystalline properties on particle shape after pulverization. Needle coke with outstanding crystallinity had high initial efficiency, and smaller particles with larger specific surface areas saw increased irreversible capacity due to the formation of SEI layers. Because of cavities existing between crystals, the poorer the crystalline properties were, the greater the capacity of the lithium ions increased. As such, regular coke had a 30 mAh/g higher discharge capacity than that of needle coke. Rate performance was more affected by particle size than by crystalline structure, and was the highest at a particle distribution of 10–15 μm.

Low-cost sodium ion batteries (SIBs) have shown hopeful perspective for large-scale energy storage systems. However, the development of carbon anode materials with high gravimetric and volumetric capacity is still a challenge. Herein, we propose a novel dense and N, P co-doped carbon derived from high density crosslinked bacterial cellulose (BC) with hexachlorocyclotriphosphazene (HCCP), which simultaneously combines high gravimetric and volumetric capacity. The as-prepared electrode demonstrates a high reversible capacity of 223 mAh g−1 at 0.05 A g−1 and superior rate performance (145 mAh g−1 at 10 A g−1) based on the overall electrode materials. The full SIBs with this electrode show a high energy density (156.1 Wh kg−1) as well as a high Coulombic efficiency in the potential range of 0–4.2 V. Density functional theory (DFT) calculation and kinetic analysis reveals that the synergistic effect of N, P co-doped configurations contributes to the superior sodium storage performance. Moreover, this electrode possesses high pressing density of 1.40 g cm−3, which increases the volumetric capacity greatly (from 97.2 to 312.2 mAh cm−3). This work proposes a new idea towards the development of low-cost bacterial cellulose that can be used in practical applications for high gravimetric and volumetric performance SIBs.

The pitch-based activated carbons were prepared with KOH/KMnO4 as a multiple function activation agent to increase the specific capacitance of a supercapacitor electrode active material. And the porous structure and electrochemical properties of activated carbon were analyzed on varying amounts of KMnO4. KMnO4 was decomposed into K2O, MnO, and O2 at the activation temperature of KOH, and MnO was introduced to activated carbon. K2O/O2 reacts with a surrounding pitch to generate micropores and forms a pathway that exposes MnO to the outside. It also affects to the specific surface area of activated carbon like KOH chemical activation. The enhanced specific surface area and introduced MnO in activated carbon led to a 28.9% increase in specific capacitance.

Activated carbon fibers (ACFs) were treated by electroless plating of CuO to improve their removal performance for volatile organic compounds (VOCs). The properties of these samples(CuO@ACFs) were evaluated by X-ray photoelectron spectroscopy (XPS), BET and N2O chemisorption to determine the area and dispersion of metallic CuO. The removal efficiency for benzene was investigated by gas chromatography (GC). The breakthrough time of CuO@ACFs increased by approximately 120% compared to that of untreated ACFs at benzene of 100 ppm. CuO@ACFs removed 100% of the benzene in 20 h, indicating this material can be used as a removal technology for VOCs.

An evaluation module based on the liquid discharge trajectory equation was developed to improve the safety as a result of chemical leakage accidents. An evaluation was performed on leakage based on changes in the vessel pressure and discharge height during a leakage accident involving a vertical storage tank containing 35% hydrochloric acid (HCl). In addition, areal locations of hazardous atmospheres (ALOHA) and the Phast program were used to evaluate the impact and dispersion range of the discharged hazardous chemicals. The evaluation results showed that installing the mitigation system resulted in a maximum 72.8% reduction in the damage impact range in the emergency response planning guideline (ERPG)-2 distance. It was also confirmed by the Phast analysis that the dispersion range and pattern were changed according to the presence of a dike. The dispersion range decreased by up to 40% depending on the presence of the dike. It was concluded that the dispersion range is related to the physical and chemical characteristics of hazardous chemicals.

In this study, the effects of activation parameters in the steam activation of polyacrylonitrile-based carbon fibers on pore formation properties were investigated. The activation temperature was used as a primary parameter, and the activation time was adjusted for each condition to obtain similar levels of activation yields. Based on the activation yield of activated carbon fibers (ACFs), the activation energy was calculated as 142.2 kJ/mole. As a result of BET analysis, it was confirmed that the specific surface area and pore volume of ACFs were improved as the activation temperature was increased. The sample treated at 850 during 45 min showed a high specific surface area (1041.9 m2/g) and a pore volume (0.49 cm3/g). This developed pore structures improved the gas adsorption properties of ACFs.

Fly ash consists of various metal oxides which can remove SO2 gas by the catalyst effect. When fly ash is added in the preparation process of pitch-based activated carbon, the pitch particles aggregate and fly ash is embedded in the activated carbon. To increase SO2 gas removal performance, activated carbon was prepared by surface-treated fly ash and petroleum-based pitch. Carboxyl groups were introduced into the fly ash by malic acid treatment. The introduced carboxyl groups acted as an activation agent to create micropore around the fly ash, and created micropores were exposed to the fly ash outside of the activated carbon. The exposed fly ash increased removal amount of SO2 gas by a catalytic effect of the metal oxides. The SO2 gas removal performance improved by 34% because of the catalyst effect of the exposed fly ash and improvement in the micropore structure in the activated carbon.

The textural (Brunauer–Emmett–Teller (BET)/density functional theory (DFT) surface energy) and chemical (oxygen-containing functional groups) properties of activated carbon fibers (ACFs) according to the electron-beam (E-beam) dose were investigated, and their dimethyl methylphosphonate (DMMP) gas sensing ability was tested. The E-beam attacked the basal plane in ACFs and generated additional lattice defects. The E-beam-irradiated ACFs exhibited a 22.2% change in resistance when upon exposure to DMMP gas. After E-beam irradiation, the surface energy of the ACFs increased because of increased roughness and oxygen-containing functional group content. As a result, the number of active sites capable of detecting DMMP increased, and the sensitivity increased.

In this study, we evaluated the potential use of CuO-ZnO combination structures with activated carbon fibers (ACFs) for the adsorption (by ACFs) and electrochemical detection (by CuO-ZnO) by of SO2 gas. The gas adsorptivity was concluded to improve as a result of the synergetic effects of physical adsorption by the micropores and mesopores, the specific surface area developed by chemical activation and the chemical adsorption reaction between SO2 and the transition metals introduced in the CuO-ZnO combination structures. From comparison of the SO2 sensing properties, the CuO-ZnO combination structures with ACFs exhibited the fastest sensing capability. This result can be attributed to the larger specific surface area of the semiconductor, which extended its depletion layer by forming p-type CuO/n-type ZnO junctions. This phenomenon led to good SO2 detection through a decrease in the resistance; thus, the contributions of the sensing responses of p-type CuO and n-type ZnO represent a predominant characteristic of the sensor. These types of mechanisms were proven through various physicochemical and electrical characterization methods, especially through evaluation of the SO2 sensing capability of the CuO-ZnO combination structures with ACFs. The reversible sensing capability indicates that the p-n junction structure changed the electrical properties of the ACFs, leading to an intriguing sensing mechanism.

To increase the energy density of today's batteries, studies on adding Si-based materials to graphite have been widely conducted. However, adding a Si-based material in the slurry mixing step suffers from low distribution due to the self-aggregation property of the Si-based material. Herein, a hierarchical structure is proposed to increase the integrity by using APS to provide a bonding effect between graphite and SiO

The bio-absorbent of Robinia pseudoacacia (R. pseudoacacia) bark was modified with sulfuric acid and their nitrate removal efficiency in water phase was investigated. At 2.5 ppm, the nitrate removal efficiency of R. pseudoacacia bark modified with 2, 4, 6, 8 and 10 M H2SO4 was 54, 61, 69, 72 and 72%, respectively, and the maximum removal efficiency was increased by 100% as compared with the raw R. pseudoacacia bark. The XPS analysis results reveal that the acidic functional groups such as carboxylic, carbonyl and phenol groups were increased by 48% in the 8M H2SO4 modified R. pseudoacacia bark, and the specific surface area and the total pore volume increased by two-times to 4.94m2/g and 0.0113 cc/g, respectively. In addition, 0.1 M sodium hydroxide performed as the best desorption agent for desorption rates using hydrochloric acid, sodium hydroxide and ethylenediamine tetraacetic acid (EDTA), in order to recover the nitrate. Collectively, these results could be employed as economical and practical engineering data for the development of nitrate removal process.

After flame-retardant treatment by the two different agents, the thermal behaviors of Lyocell fibers are discussed. In this research, H3PO4 and NaCl reduced the degradation rate and increased the char yield of the Lyocell fibers, and also increased the limiting oxygen index with the char yield increased. After treatment, the integral procedure decomposition temperature and the activation energy of Lyocell fibers are significantly increased by various concentration factors. These phenomena were indicated by the dehydration, rearrangement, formation of carbonyl groups, the evolution of carbon monoxide and dioxide, and carbonaceous residue formation. These effects were indicating the slow pathway of flame retardancy for the Lyocell fibers and are attributed to the two different flame-retardant agent treatments.

To enhance mechanical properties through improvement of dispersion stability of carbon black (CB) in epoxy resins, fluorine functional groups were introduced on the CB surface by fluorination. The changes in the chemical properties and dispersion stabilities after fluorination were evaluated with different partial pressures of fluorine gas. The mechanical properties of the fluorinated CB/epoxy composites were evaluated by the test of tensile, impact strengths and creep behavior. The fluorinated CB/epoxy composites showed approximately 1.6 and 1.1 times enhancement in the tensile and impact strengths compared to that of neat epoxy, respectively. Moreover, when a constant load was applied at 323 K, the fluorinated CB/epoxy composites lasted longer and had smaller strain changes than those of the raw CB/epoxy composites. Thus, well-dispersed CB by fluorination in epoxy resins effectively transfers mechanical stress.

To achieve high-performance nitric oxide (NO) gas sensing, expanded graphite (EG) was modified with SnO2 and fluorine functional groups. SnO2 was introduced into EG with an aqueous solution of SnCl2, whereas the fluorine functional groups were introduced via fluorine gas. The properties of the samples were analyzed by field-emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and NO gas sensing. A SnO2 phase from the SnCl2 solution formed on and uniformly coated the EG surface. The number of fluorine functional groups increased with increasing fluorination temperature. The EG/SnO2 fluorinated at 400 ℃ exhibited the highest NO gas sensitivity (5.2%). The SnO2 induced the adsorption of NO gas, and the fluorine functional groups transferred electrons from the EG surface to the NO gas adsorbed onto SnO2. Therefore, the high NO gas sensitivity is attributed to the synergistic effect of the introduced SnO2 and fluorine functional groups.

To enhance the thermal properties of epoxy composites, expanded graphite (EG) was oxyfluorinated and embedded into epoxy resin as a reinforcement. The maximum thermal conductivity was obtained for epoxy composites with oxyfluorinated EG, representing a 62% increase compared to that of neat epoxy. Additionally, the glass transition temperature (Tg) and integral procedural decomposition temperature of epoxy composites with oxyfluorinated EG show the increase of 6% (4.4 °C) and 106% (264 °C), respectively, which indicated the improvement in thermal stability. These results can be attributed to the interfacial interaction between epoxy and oxyfluorinated EG, which formed strong interfacial interactions between the epoxy resin and EG due to the presence of oxygen- and fluorine-containing functional groups in oxyfluorinated EG.

C F bonds are introduced on activated carbon (AC) by fluorination, and the resulting fluorinated AC (FAC) is fabricated into electrodes to investigate the effect of C F bonds on the capacitive deionization (CDI) performance. The concentration of C F bonds on the AC surface is a high as 19.5%, but the specific surface area of FAC is reduced by etching of the pore walls. Nevertheless, the specific capacitance of FAC is up to 30% higher than that of raw AC (RAC). The negative surface charge formed by the electronegativity difference between carbon and fluorine causes an increase in the open circuit potential (OCP) of the CDI cell, which results in a higher charge efficiency. Therefore, the specific electrosorption capacity of FAC is 16.5 mg g−1, which increased by 59% compare to that of RAC. These results are attributed to multiple factors of the negative surface charge and the OCP formed by C F bonds, which diminish the co-ion expulsion effect, thereby enhancing the CDI performance.