Direct Double Coating of Carbon and Nitrogen on Fluoride-Doped Li4Ti5O12 as an Anode for Lithium-Ion Batteries

Graphite as a commercial anode for lithium-ion batteries has significant safety concerns owing to lithium dendrite growth at low operating voltages. Li4Ti5O12 is a potential candidate to replace graphite as the next-generation anode of lithium-ion batteries. In this work, fluoride-doped Li4Ti5O12 was successfully synthesized with a direct double coating of carbon and nitrogen using a solid-state method followed by the pyrolysis process of polyaniline. X-ray diffraction (XRD) results show that the addition of fluoride is successfully doped to the spinel-type structure of Li4Ti5O12 without any impurities being detected. The carbon and nitrogen coating are distributed on the surface of Li4Ti5O12 particles, as shown in the Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (SEM-EDS) image. The Transmission Electron Microscopy (TEM) image shows a thin layer of carbon coating on the Li4Ti5O12 surface. The fluoride-doped Li4Ti5O12 has the highest specific discharge capacity of 165.38 mAh g−1 at 0.5 C and capacity fading of 93.51% after 150 cycles compared to other samples, indicating improved electrochemical performance. This is attributed to the synergy between the appropriate amount of carbon and nitrogen coating, which induced a high mobility of electrons and larger crystallite size due to the insertion of fluoride to the spinel-type structure of Li4Ti5O12, enhancing lithium-ion transfer during the insertion/extraction process.

EVALUASI COATING MATERIALS UNTUK MELINDUNGI BAKTERI PROBIOTIK PSEUDOALTEROMONAS PISCICIDA SELAMA PROSES MIKROENKAPSULASI DAN PENYIMPANAN

Disease is an obstacle in Pacific white shrimp culture that can cause economic losses. Probiotic bacteria Pseudalteromonas piscicida 1Ub RfR is able to improve the growth performance and immune responses of Pacific white shrimp and has the potential to be developed into dry products to make it more practical for use in the field. This study aims to obtain the best coating materials that can protect probiotic bacteria during the microencapsulation and storage process. This research was conducted in September-December 2020 at the Laboratory of Microbiology of IPB Sukabumi Campus and South-East Asia Food and Agricultural Science and Technology (SEAFAST). This research consists of 2 Chapters, Chapter 1 to obtain the best coating materials and Chapter 2 to obtain the best results after the microencapsulation process. Coating materials used in this study were whey protein and maltodextrin. The microencapsulation technique used is freeze drying and spray drying. The probiotic bacteria used was P. piscicida from Fish Health and Management Laboratory, Department of Aquaculture, FPIK IPB and was marked with rifampicin resistance (1Ub RfR). The research in Chapter 1 consisted of 4 treatments, including K (without coating material), A (single coating with whey protein), B (single coating with maltodextrin), and C (double coating with whey protein and maltodextrin). Furthermore, each treatment in Chapter 1 is continued for the microencapsulation process. The results showed that the treatment with double coating and encapsulated by freeze drying was the best probiotic products compared other treatments.

Double Coating as a Novel Technology for Controlling Urea Dissolution in Soil: A Step toward Improving the Sustainability of Nitrogen Fertilization Approaches

This research introduces a novel technology for reducing ordinary urea (OU) dissolution by developing double-coated urea (DCU) using phosphate rock (PR) as an outer layer to reduce its hydrolysis and sodium thiosulfate (STS) as an inner layer to inhibit the urease enzyme and nitrification process. Due to the double coating, the nitrogen content of DCU was lower than that of the OU (36.7% vs. 46.5%). The ultramorphological analysis using scanning electron microscopy (SEM) indicated that the controlled coating of urea, resulting from the outer layer of PR, was due to the adhesive effect of urea formaldehyde (UF), which was used as a glue. In addition, the transmission electron microscopy (TEM) analysis of the DCU revealed its high degree of agglomeration. The mechanical hardness of DCU was higher compared to that of OU (1.38 vs. 1.08 kgf). The seven-day dissolution rate test showed that OU reached 100% dissolution on the fifth day. The rate of DCU, however, was significantly lower (32% dissolution in the seventh day). Cumulative NO3− and NH4+ losses from a clay soil sample reached 68.3% and 7.6%, respectively, with OU measuring 40.5% compared to 4.9% for DCU 70 days after application. Field experiments showed a significant improvement in the marketable yield and agronomic nitrogen efficiency (ANE) of maize grains and zucchini fruits fertilized with DCU. Furthermore, the macro and micronutrient concentrations in maize grains and zucchini fruits showed an increase in the plants fertilized with DCU. In summary, double coating can be introduced as a novel technique to control urea dissolution in soil.

Functional Method of Designing Self-Compacting Concrete

The article presents a new functional method of designing self-compacting concrete (SCC). The assumptions of the functional method of designing self-compacting concrete were based on the double coating assumption (i.e., it was assumed that the grains of coarse aggregate were coated with a layer of cement mortar, whereas the grains of sand with cement paste). The proposed method is composed of four stages, each of which is responsible for the selection of a different component of the concrete mix. The proposed designing procedure takes into consideration such a selection of the mineral skeleton in terms of the volumetric saturation of the mineral skeleton, which prevents the blocking of aggregate grains, and the designed liquid phase demonstrated high structural viscosity and low yield stress. The performed experimental studies, the simulation of the elaborated mathematical model fully allowed for the verification of the theoretical assumptions that are the basis for the development of the method of designing self-compacting concrete.