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.

This paper reports the microstructure and electrochemical properties of Si-Al-Fe ternary amorphous alloys prepared by rapid solidification as an anode for lithium secondary batteries. The microstructure was analyzed using XRD and HR-TEM with EDS mapping. In accordance with DSC analysis, annealing was performed to crystallize the active nano-Si in the amorphous alloy. Thus, nano-Si forms (~80 nm) embedded in the matrix alloy, such as Fe₂Al₃Si₃, FeSi₂, and Fe_0.42Si_2.67, were successfully synthesized. The electrode based on the Si-Al-Fe ternary alloy delivered an initial discharge capacity of approximately 700 mAh ^g-1, and exhibited a high Coulombic efficiency of 99.0~99.6% from the 2^nd to 70^th cycles.

This work investigated the effects of different conductive agents on the electrochemical properties of anodes. SiOx possesses high theoretical capacity and shows excellent cycle performance; however, the low initial coulombic efficiency and poor electrical conductivity limit its applications in real batteries. In this study, electrodes were fabricated using two different conductive agents, and the resulting physical and electrochemical properties were analyzed. SEM observations confirmed the formation of a CNT conductive network throughout the electrodes, while the electrical conductivity contributed to the electrode was confirmed by impedance measurements. Thus, the electrode fabricated with the CNT conductive agent showed greater capacity and superior cycle performance than did the electrode fabricated using the DB conductive agent.

SiO_x nanoparticles were granulated, and their microstructures and effects on electrochemical behaviors were investigated. In spite of the promising electrochemical performance of SiO_x, nanoparticles have limitations such as high surface area, low density, and difficulty in handling during slurry processing. Granulation can be one solution. In this study, pelletizing and annealing were conducted to create particles with sizes of several decades of micron. Decrease in surface area directly influences the initial charge and discharge process when granules are applied as anode materials for Li-ion batteries. Lower surface area is key to decreasing the amount of irreversible phase-formation, such as Li₂Si₂O₅, Li₂SiO₃ and LuSiO₄, as well as forming the solid electrolyte interface. Additionally, aggregation of nanoparticles is required to obtain further enhancement of the electrochemical behavior due to restrictions that there be no Li₄SiO₄-related reaction during the first discharge process.

The effect of various lithium sources such as LiCl, LiOH, and Li-metal on the microstructure and electrochemical properties of granulated SiO_x powders were investigated. Various lithium sources were metallurgically added for a passive pre-lithiation of SiO_x to improve its low initial coulombic efficiency. In spite of using the same amount of Li in various sources, as well as the same process conditions, different lithium silicates were obtained. Moreover, irreversible phases were formed without reduction of SiO_x, which might be from additional oxygen incorporation during the process. Accordingly, there were no noticeable electrochemical enhancements. Nevertheless, the Li₄SiO₄ phase changes the initial electrochemical reaction, and consequently the relationship between the microstructure and electrochemical properties of metallurgically pre-lithiated SiO_x could provide a guideline for the optimization of the performance of lithium ion batteries.

Renewable energy sources such as solar, wind and hydro provides utilizing renewable power and reduce the using fossil fuels. On the other hand, it is too critical to apply power system due to the intermittent nature of renewable energy sources, the continuous fluctuations of the power load, and the storage with high energy density. Energy storage system, including pumped-hydroelectric energy storage, compressed-air energy storage, superconducting magnetic energy storage, and electrochemical devices like batteries, super capacitors and others have shown that solve some of the challenges. In this paper, were view the current state of applications of energy storage systems, and atomic layer deposition technology, graphene materials on the energy storage systems and processes.

Synthesis of Li2MnSiO4 was attempted by the conventional solid-state reaction method, and the phase formation behavior according to the change of the calcination condition was investigated. When the mixture of the three source materials, Li2O, MnO and SiO2 powders, were used for calcination in air, it was difficult to develop the Li2MnSiO4 phase because the oxidation number of Mn2+ could not be maintained. Therefore, two-step calcination was applied: Li2SiO3 was made from Li2O and SiO2 at the first step, and Li2MnSiO4 was synthesized from Li2SiO3 and MnO at the second step. It was easy to make Li2SiO3 from Li2O and SiO2. Li2MnSiO4 single phase was developed by the calcination at 900℃ for 24 hr in Ar atmosphere as the oxidation of Mn2+ was prevented. However, the Li2MnSiO4 was γ -Li2MnSiO4, one of the polymorph of Li2MnSiO4, which could not be used as the cathode materials in Li-ion batteries. By applying the additional low temperature annealing at 400℃, the single phase β -Li2MnSiO4 powder was synthesized successfully through the phase transition from γ to β phase.