• Journal of Electrochemical Science and Technology
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• 제11권4호
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• pp.352-360
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• 2020

Lithium cobalt oxide (LiCoO₂, LCO) has been widely used as a cathode material for Li-ion batteries (LIBs) owing to its excellent electrochemical performance and highly reproducible synthesis even with mass production. To improve the energy density of the LIBs for their deployment in electro-mobility, the full capacity and voltage of the cathode materials need to exploited, especially by operating them at a higher voltage. Herein, we doped LCO with divalent calcium-ion (Ca²⁺) to stabilize its layered structure during the batteries' operation. The Ca-doped LCO was synthesized by two different routes, namely solid-state and co-precipitation methods, which led to different average particle sizes and levels of dopant's homogeneity. Of these two, the solid-state synthesis resulted in smaller particles with a better homogeneity of the dopant, which led to better electrochemical performance, specifically when operated at a high voltage of 4.5 V. Electrochemical simulations based on a single particle model provided theoretical corroboration for the positive effects of the reduced particle size on the higher rate capability.

• Journal of Electrochemical Science and Technology
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• 제13권3호
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• pp.407-415
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• 2022

Surface coating of cathodes is an essential process for all-solid-state batteries (ASSBs) based on sulfide electrolytes as it efficiently suppresses interfacial reactions between oxide cathodes and sulfide electrolytes. Based on computational calculations, Li₃PO₄ has been suggested as a promising coating material because of its higher stability with sulfides and its optimal ionic conductivity. However, it has hardly been applied to the coating of ASSBs due to the absence of a suitable coating process, including the selection of source material that is compatible with ASSBs. In this study, polyphosphoric acid (PPA) and (NH₄)₂HPO₄ were used as source materials for preparing a Li₃PO₄ coating for ASSBs, and the properties of the coating layer and coated cathodes were compared. The Li₃PO₄ layer fabricated using the (NH₄)₂HPO₄ source was rough and inhomogeneous, which is not suitable for the protection of the cathodes. Moreover, the water-based coating solution with the (NH₄)₂HPO₄ source can deteriorate the electrochemical performance of high-Ni cathodes that are vulnerable to water. In contrast, when an alcohol-based solvent was used, the PPA source enabled the formation of a thin and homogeneous coating layer on the cathode surface. As a consequence, the ASSBs containing the Li₃PO₄-coated cathode prepared by the PPA source exhibited significantly enhanced discharge and rate capabilities compared to ASSBs containing a pristine cathode or Li₃PO₄-coated cathode prepared by the (NH₄)₂HPO₄ source.

• 한국전기전자재료학회논문지
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• 제37권4호
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• pp.445-450
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• 2024

The expansion of lithium-ion battery usage beyond portable electronic devices to electric vehicles and energy storage systems is driven by their high energy density and favorable cycle characteristics. Enhancing the stability and performance of these batteries involves exploring solid electrolytes as alternatives to liquid ones. While sulfide-based solid electrolytes have received significant attention for commercialization, research on amorphous-phase glass solid electrolytes in oxide-based systems remains limited. Here, we investigate the glass transition temperatures and sintering behaviors by changing the molecular ratio of Li₂O/B₂O₃ in borate glass comprising Li₂O-B₂O₃-Al₂O₃ system. The glass transition temperature is decreasing as increasing the amount of Li₂O. When we sintered at 450℃, just above the glass transition temperature, the samples did not consolidate well, while the proper sintered samples could be obtained under the higher temperature. We successfully obtained the borate glass ceramics phases by melt-quenching method, and the sintering characteristics are investigated. Future studies could explore optimizing ion conductivity through refining processing conditions, adjusting the glass former-to-modifier ratio, and incorporating additional Li salt to enhance the ionic conductivity.

• International journal of advanced smart convergence
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• 제13권1호
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• pp.206-211
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• 2024

This study used a total of 205,565 datasets of 'voltage', 'current', '℃', and 'time(s)' to systematically analyze the properties and performance of solid electrolytes. As a method for characterizing solid electrolytes, a linear regression model, one of the machine learning models, is used to visualize the relationship between 'voltage' and 'current' and calculate the regression coefficient, mean squared error (MSE), and coefficient of determination (R^2). The regression coefficient between 'Voltage' and 'Current' in the results of the linear regression model is about 1.89, indicating that 'Voltage' has a positive effect on 'Current', and it is expected that the current will increase by about 1.89 times as the voltage increases. MSE found that the mean squared error between the model's predicted and actual values was about 0.3, with smaller values closer to the model's predictions to the actual values. The coefficient of determination (R^2) is about 0.25, which can be interpreted as explaining 25% of the data.

• Journal of Electrochemical Science and Technology
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• 제11권3호
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• pp.282-290
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• 2020

In this article, we report the effect of blended cathode materials on the performance of all-solid-state lithium-ion batteries (ASLBs) with oxide-based organic/inorganic hybrid electrolytes. LiFePO₄ material is good candidates as cathode material in PEO-based solid electrolytes because of their low operating potential of 3.4 V; however, LiFePO₄ suffers from low electric conductivity and low Li ion diffusion rate across the LiFePO₄/FePO₄ interface. Particularly, monoclinic Li₃V₂(PO₄)₃ (LVP) is a well-known high-power-density cathode material due to its rapid ionic diffusion properties. Therefore, the structure, cycling stability, and rate performance of the blended LiFePO₄/Li₃V₂(PO₄)₃ cathode material in ASLBs with oxidebased inorganic/organic-hybrid electrolytes are investigated by using powder X-ray diffraction analysis, field-emission scanning electron microscopy, Brunauer-Emmett-Teller sorption experiments, electrochemical impedance spectroscopy, and galvanostatic measurements.

• 한국자기공명학회:학술대회논문집
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• 한국자기공명학회 2000년도 동계총회 및 제16회 자기공명 학술발표회
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• pp.27-27
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• 2000

• 한국세라믹학회지
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• 제53권6호
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• pp.712-718
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• 2016

In this study, we investigate the effect of the$Li_3BO_3$ additive on the densification and ionic conductivity of garnet-type $Li_7La_3Zr_2O_{12}$ solid electrolytes for all-solid-state lithium batteries. We analyze their densification behavior with the addition of $Li_3BO_3$ in the range of 2-10 wt.% by dilatometer measurements and isothermal sintering. Dilatometry analysis reveals that the sintering of $Li_7La_3Zr_2O_{12}-Li_3BO_3$ composites is characterized by two stages, resulting in two peaks, which show a significant dependence on the $Li_3BO_3$ additive content, in the shrinkage rate curves. Sintered density and total ion conductivity of the system increases with increasing $Li_3BO_3$ content. After sintering at $1100^{\circ}C$ for 8 h, the $Li_7La_3Zr_2O_{12}-8$ wt.% $Li_3BO_3$ composite shows a total ionic conductivity of $1.61{\times}10^{-5}Scm^{-1}$, while that of the pure $Li_7La_3Zr_2O_{12}$ is only $5.98{\times}10^{-6}Scm^{-1}$.

• 한국전기화학회:학술대회논문집
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• 한국전기화학회 2003년도 전지기술심포지움
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• pp.153-168
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• 2003

Polymer electrolytes - solid polymeric membranes with dissolved salts - are being intensively studied for use in all-solid-state lithium-metal-polymer consumer electronic device. The low ionic conductivity at room temperature of existing polymer electrolytes, however, has seriously hindered the development of such batteries for many applications. The incorporation of salts molten at room temperature (room temperature ionic liquids or RTILs) into polymer electrolytes may be the necessary solution to overcoming the inherent ionic conductivity limitations of 'dry' polymer electrolytes.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.232-235
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• 1998

ion conducting polymers have been extensively investigated because of their potential application as an electrolyte in solid state batteries [1]. Among the polymer electrolytes, solid polymer electrolytes (SPEs) composed of ion conducting polymer and alkali metal salt have many advantages such as high ionic conductivity, high energy density and light weight. This made them suitable replacement for liquid electrolytes. (omitted)

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.3-4
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• 2007

Many electrochemical power devices such as solid state batteries and solid oxide fuel cell have been studied and developed for solving energy and environmental problems. Fuel cell is a modular, high efficient and environmentally energy conversion device, it has become a promising option to replace the conventional fossil fuel based electric power plants. This paper offers some new perspectives on fuel cell development and commercialization which come from the broad consideration of the commercialization efforts of the entire fuel cell industry.