• Journal of Electrochemical Science and Technology
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• 제2권3호
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• pp.146-151
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• 2011

The formation of Li-Si-O phases, $Li_4SiO_4$ and $Li_2SiO_3$ from the starting materials SiO and $Li_2O$ are analyzed using Vienna Ab-initio Simulation (VASP) package and the total energies of Li-Si-O compounds are evaluated using Projector Augmented Wave (PAW) method and correlated the structural characteristics of the binary system SiO-$Li_2O$ with experimental data from electrochemical method. Despite $Li_2SiO_3$ becomes stable phase by virtue of lowest formation energy calculated through VASP, the experimental method shows presence of $Li_4SiO_4$ as the only product formed when SiO and $Li_2O$ reacts during slow heating to reach $550^{\circ}C$ and found no evidence for the formation of $Li_2SiO_3$. Also, higher density of $Li_4SiO_4$(2.42 g $ml^{-1}$) compared to the compositional mixture $1SiO_2-2Li_2O$ (2.226 g $ml^{-1}$) and better cycle capacity observed through experiment proves that $Li_4SiO_4$ as the most stable anode supported by better cycleabilityfor lithium ion battery remains as paradox from the point of view of VASP calculations.

• Journal of Ceramic Processing Research
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• 제13권spc1호
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• pp.37-41
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• 2012

A lithium ion conducting borosilicate glass was fabricated by a conventional melt quenching technique from a mixture of Li2CO3, B2O3 and SiO2 powders. The Li ion conductivity of the lithium borosilicate glasses was evaluated in terms of the SiO2/B2O3 ratio. In the Li2O-B2O3-SiO2 ternary glass, the glass forming region decreases with an increasing Li2O content. At the same Li2O, the crystallization tendency of the glass samples increases with the SiO2/B2O3 ratio, resulting in a reduced glass forming region in the Li2O-B2O3-SiO2 ternary glass. The electrical conductivity moderately depends on the SiO2/B2O3 ratio in the Li2O-B2O3-SiO2 ternary glass. The conductivity of the glasses slightly increases with the SiO2/B2O3 ratio. The observed phenomenon can be explained by the modification of the glass structure as a function of the SiO2 content.

• 대한화학회지
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• 제50권3호
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• pp.232-236
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• 2006

형광체의 특성을 향상시키기 위하여 Y1.99-xMxCe0.01SiO5(M=Li, La, Nd, and Gd)를 환원분위기에서 1350oC, 10시간동안 고상반응법으로 합성하였다. 상용품인 청색 형광체와 비교를 했을 때, 다양한 원소를 치환한 Y2SiO5:Ce 청색 형광체의 발광 특성이 우수 하다는 것을 관찰 할 수 있었다. 특히, 1mol%의 Li 이온이 도핑된 Y2SiO5:Ce 청색 형광체의 광 발광 특성이 가장 높았다. Y2SiO5:(Ce,Li) 청색 형광체의 입도형상을 주사전자현미경으로 분석한 결과, 입자의 크기가 약 3m인 유사구형임을 확인하였다.

• 한국전기전자재료학회논문지
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• 제25권5호
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• pp.398-402
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• 2012

Synthesis of $Li_2MnSiO_4$ 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, $Li_2O$, MnO and $SiO_2$ powders, were used for calcination in air, it was difficult to develop the $Li_2MnSiO_4$ phase because the oxidation number of $Mn^{2+}$ could not be maintained. Therefore, two-step calcination was applied: $Li_2SiO_3$ was made from $Li_2O$ and $SiO_2$ at the first step, and $Li_2MnSiO_4$ was synthesized from $Li_2SiO_3$ and MnO at the second step. It was easy to make $Li_2MnSiO_3$ from $Li_2O$ and $SiO_2$. $Li_2MnSiO_4$ single phase was developed by the calcination at $900^{\circ}C$ for 24 hr in Ar atmosphere as the oxidation of $Mn^{2+}$ was prevented. However, the $Li_2MnSiO_4$ was ${\gamma}-Li_2MnSiO_4$, one of the polymorph of $Li_2MnSiO_4$, which could not be used as the cathode materials in Li-ion batteries. By applying the additional low temperature annealing at $400^{\circ}C$, the single phase ${\beta}-Li_2MnSiO_4$ powder was synthesized successfully through the phase transition from ${\gamma}$ to ${\beta}$ phase.

• 한국세라믹학회지
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• 제41권8호
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• pp.593-598
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• 2004

1 $\mu$m이하의 전고상 리튬 박막전지의 구현을 위해 펄스 레이저 증착법을 이용하여 Pt/TiO$_2$/SiO$_2$/Si 기판위에 LiCoO$_2$정극을 증착온도와 Li/Co 간의 몰 비율을 변화시켜가며 성장시켰다. 특히, Li/Co=1.2의 조성을 갖는 LiCoO$_2$를 50$0^{\circ}C$의 증착온도에서 성장시킬 경우 53 $\mu$Ah/$cm^2$-$\mu$m의 높은 초기 용량값을 가지며 100 싸이클 후에도 67.6%의 용량값을 유지하였다. LiCoO$_2$/Pt/TiO$_2$/SiO$_2$/Si위에 고체 전해질인 (Li, La)TiO$_3$를 비정질상으로 하여 PLD방법으로 낮은 온도대역에서 증착온도를 다양하게 하여 증착하였다. 10$0^{\circ}C$의 증착온도에서 LiCoO$_2$Pt/TiO$_2$/SiO$_2$/Si위에 성장시킨 (Li, La)TiO를 가지고 LiClO$_4$ in PC 안에서 Li anode와 충$.$방전 측정 결과 약 51$\mu$Ah/$cm^2$-$\mu$m의 초기 용량값을 나타내었으며 100싸이클 후에도 90%의 훌륭한 방전용량의 보존력을 나타내었다. 비정질상의 (Li, La)TiO$_3$ 고체 전해질은 전고상 박막전지로의 구현이 가능하다.

• Nuclear Engineering and Technology
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• 제55권8호
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• pp.2966-2976
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• 2023

A tritium breeder is a lithium-based material capable of producing tritium. Many researchers designing nuclear-fusion energy are studying tritium production using pebbles, which are solid-type breeders. The sphericity and size of the pebbles are critical in obtaining pebbles with good tritium-breeding efficiency. Furthermore, tritium-release efficiency can be increased by using pebbles with appropriate porosities. Promising raw materials for tritium-breeding materials include Li₄SiO₄ and Li₂TiO₃. Li₄SiO₄ has a higher lithium density than Li₂TiO₃ and exhibits excellent tritium-breeding efficiency. However, it has the disadvantage of being easily decomposed during the Li₄SiO₄-green-pebble sintering process because of its low structural stability at high temperatures and high lithium density. In this study, we attempted to determine the optimal conditions for manufacturing Li₄SiO₄ pebbles using the droplet-freeze-drying method. The optimal Li₄SiO₄ slurry conditions and sintering temperatures were determined. The optimal Li₄SiO₄ slurry-fabrication conditions were 3 wt% polyvinyl alcohol and 75 wt% Li₄SiO₄ based on the deionized-water weight content. The sintering temperature at which Li₄SiO₄ did not decompose and exhibited the optimum porosity of 10.8% was 900 ℃.

• Journal of Electrochemical Science and Technology
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• 제8권2호
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• pp.101-106
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• 2017

$Li_2SiO_3$ was used as a coating material to improve the electrochemical performance of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$. $Li_2SiO_3$ is not only a stable oxide but also an ionic conductor and can, therefore, facilitate the movement of lithium ions at the cathode/electrolyte interface. The surface of the $Li_2SiO_3$-coated $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ was covered with island-type $Li_2SiO_3$ particles, and the coating process did not affect the structural integrity of the $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ powder. The $Li_2SiO_3$ coating improved the discharge capacity and rate capability; moreover, the $Li_2SiO_3$-coated electrodes showed reduced impedance values. The surface of the lithium-ion battery cathode is typically attacked by the HF-containing electrolyte, which forms an undesired surface layer that hinders the movement of lithium ions and electrons. However, the $Li_2SiO_3$ coating layer can prevent the undesired side reactions between the cathode surface and the electrolyte, thus enhancing the rate capability and discharge capacity. The thermal stability of $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ was also improved by the $Li_2SiO_3$ coating.

• 한국전기전자재료학회논문지
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• 제30권7호
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• pp.447-453
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• 2017

In this study, $Li_2MnSiO_4$ cathode material and LiPON solid electrolyte were manufactured into thin films, and the possibility of their use in thin-film batteries was researched. When the RTP treatment was performed after $Li_2MnSiO_4$ cathode thin-film deposition on the SUS substrate by a sputtering method, a ${\beta}-Li_2MnSiO_4$ cathode thin film was successfully manufactured. The LiPON solid electrolyte was prepared by a reactive sputtering method using a $Li_3PO_4$ target and $N_2$ gas, and a homogeneous and flat thin film was deposited on a $Li_2MnSiO_4$ cathode thin film. In order to evaluate the electrochemical properties of the $Li_2MnSiO_4$ cathode thin films, coin cells using only a liquid electrolyte were prepared and the charge/discharge test was conducted. As a result, the amorphous thin film of RTP treated at $600^{\circ}C$ showed the highest initial discharge capacity of about $60{\mu}Ah/cm^2$. In cases of coin cells using liquid/solid double electrolyte, the discharge capacities of the $Li_2MnSiO_4$ cathode thin films were comparable to those without solid LiPON electrolyte. It was revealed that $Li_2MnSiO_4$ cathode thin films with LiPON solid electrolyte were applicable in thin film batteries.

• E2M - 전기 전자와 첨단 소재
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• 제10권2호
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• pp.166-171
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• 1997

The photomachinable glass-ceramics of Ag and CeO$_{2}$ added to Li$_{2}$O-Al$_{2}$O$_{3}$-SiO$_{2}$-K$_{2}$O glass system was investigated as a function of UV irradiation time. The temperature of optimum nucleation and crystal growth temperature were confirmed at 525.deg. C, 630.deg. C respectively using DTA and TMA. The phases of Li$_{2}$O.SiO$_{2}$ habit were lath-like and/or dendrite type and [002] direction of Li$_{2}$O.SiO$_{2}$ / Li$_{2}$O.2SiO$_{2}$ phases were changed according to the UV irradiation time by 400 W, 362 nm UV light source. Under that condition, the optimum UV irradiation time was 5 min.

• 전기화학회지
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• 제18권4호
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• pp.143-149
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• 2015

Planetary ball mill과 고상반응법을 사용하여 실리케이트계 탄소 코팅된 $Li_2MnSiO_4$ 양극활물질 분말을 합성하였으며 충방전 특성을 조사하였다. 전기화학적 활성을 지니는 ${\beta}-Li_2MnSiO_4$ 상을 형성하기 위하여 하소 온도와 분위기를 조절하였으며 ${\beta}-Li_2MnSiO_4$ 단일상에 가까운 탄소 코팅된 $Li_2MnSiO_4$ 활물질 분말을 제조할 수 있었다. 합성된 분말은 100 nm 정도 크기의 1차 입자가 뭉쳐있는 2차 입자 형태를 보였다. $Li_2MnSiO_4$ 활물질에서 Li의 삽입/탈리가 가능하려면 탄소의 첨가가 필요하였으며, 4.8 wt%의 탄소가 코팅된 $Li_2MnSiO_4$ 활물질에서 초기용량 192 mAh/g를 얻을 수 있었다.