• Advances in materials Research
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• v.4 no.2
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• pp.63-76
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• 2015

The energy crisis involving depletion of fossil fuel resource is not the sole driving force for developing renewable energy technologies. Another driving force is the ever increasing concerns on the air quality of our planet, associated with the continuous and dramatic increase of the concentration of greenhouse gas (mainly carbon dioxide) emissions. The internal combustion engine is a major source of distributed $CO_2$ emissions caused by combustion of gasoline derived largely from fossil fuel. Another major source of $CO_2$ is the combustion of fossil fuels to produce electricity. New technologies for generating electricity from sources that do not emit $CO_2$, such as water, solar, wind, and nuclear, together with the advent of plug-in hybrid electric vehicles (PHEV) and even all-electric vehicles (EVs), offer the potential of alleviating our present problem. Therefore, the relevant technologies in $LiFePO_4$ as cathode material for Li-ion batteries suitable to the friendly environment are reviewed aim to provide the vital information about the growing field for energies to minimize the potential environmental risks.

• Journal of Electrochemical Science and Technology
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• v.4 no.3
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• pp.102-107
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• 2013

The electrochemical properties of Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ and pure $LiFe_{0.5}Mn_{0.5}PO_4$ olivine cathodes are examined and the lattice parameters are refined by Rietveld analysis. The calculated atomic parameters from the refinement show that $Mg^{2+}$ doping has a significant effect in the olivine $LiFeMnPO_4$ structure. The unit cell volume is 297.053(2) ${\AA}^3$ for pure $LiFe_{0.5}Mn_{0.5}PO_4$ and is decreased to 296.177(1) ${\AA}^3$ for Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample. The doping of $Mg^{2+}$ cation with atomic radius smaller than $Mn^{2+}$ and $Fe^{2+}$ ion induces longer Li-O bond length in $LiO_6$ octahedra of the olivine structure. The larger interstitial sites in $LiO_6$ octahedra facilitate the lithium ion migration and also enhance the diffusion kinetics of olivine cathode material. The $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample with larger Li-O bond length delivers higher discharge capacities and also notably increases the rate capability of the electrode.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.8
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• pp.702-707
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• 2005

Spinel $LiMn_2O_4$ has become appealing because manganese is inexpensive and environmentally benign. In general, cathodes for lithium ion batteries include carbon as a conductive agent that provides electron transfer between the active material and the current collector. In this work, we selected Acetylene Black and Super P Black as conductive agents, and then carried out their comparative investigation for the performances of the $Li/LiMn_2O_4$ cells using different conductive agents with different particle size. In addition, their electrochemical impedance characteristic of $Li/Mn_2O_4$ cells using different conductive agents is effectively identified through a.c. impedance technique. As a consequence, $Li/LiMn_2O_4$ cells with Super P Black show better electrochemical performances ascribed to the significant contribution of feasible ionic conduction due to larger particle size than those with Acetylene Black.

• Journal of the Korean Electrochemical Society
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• v.8 no.4
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• pp.168-171
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• 2005

The electrochemical properties of $LiFePO_4$ as a cathode for Li-ion batteries were improved by incorporating conductive carbon into the $LiFePO_4$. X-ray diffraction analysis and SEM observations revealed that the carbon-coated $LiFePO_4$ consisted of fine single crystalline particles, which were smaller than the bare $LiFePO_4$. The electrochemical performance of the carbon-coated $LiFePO_4$ was tested under various conditions. The carbon-coated $LiFePO_4$ showed much better performance in terms of the discharge capacity and cycling stability than the bare $LiFePO_4$. The improved electrochemical performances were found to be attributed to the reduced particle size and enhanced electrical conductivity of the $LiFePO_4$ by the carbon.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.340-341
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• 2005

Lithium titanium oxide as anode material for energy storage prepared by novel synthesis method. $Li_4Ti_5O_{12}$ based spinel-framework structures are of great interest material for lithium-ion batteries. We describe here $Li_4Ti_5O_{12}$ a zero-strain insertion material was prepared by novel sol-gel method and by high energy ball milling (HEBM) of precursor to from nanocrystalline phases. According to the X-ray diffraction and scanning electron microscopy analysis, uniformly distributed $Li_4Ti_5O_{12}$ particles with grain sizes of 100nm were synthesized. Lithium cells, consisting of $Li_4Ti_5O_{12}$ anode and lithium cathode showed the 173 mAh/g in the range of 1.0 $\sim$ 3.0 V. Furthermore, the crystalline structure of $Li_4Ti_5O_{12}$ didn't transfer during the lithium intercalation and deintercalation process.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2939-2942
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• 2003

A new contactless Li-ion battery charging system was proposed. The conventional methods for charging Li-ion battery have some weak points. For example, there can be a contact failure, a poor waterproof, and a difficulty to standardize the battery charging systems. The new proposed system can overcome these weak points. The new charging system is composed of power transfer part and data transfer part. This paper focuses on the power transfer part for contactless battery charging. The power stage is mainly composed of PPRC(Push-pull Parallel Resonant Converter) and flyback converter. The new method of chaging Li-ion battery was proposed and PPRC + flyback-boost topology was analyzed. The proposed toplogy was tested under the constant voltage control and the constant current control which are adequate for charging Li-ion battery.

• Proceedings of the KIPE Conference
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• 2011.11a
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• pp.22-23
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• 2011

본 논문은 Battery의 열화 특성을 반영한 순차적 Step Charge를 통한, Mobile 기기용 Li-Ion Smart Battery의 Life Cycle 개선기술을 제안 하고자 한다. 현재 기술수준의 Li-Ion 2차전지 수명은 표준충방전 300~500cycle 내외이나. 초기용량을 희생하지 않고도 Smart Battery 내부의 ASOC(Absolute State of Charge)와 연동하여 Battery 수명열화 곡선을 추종하는 최적화된 가변 충전전압을 순차적 Step Charge로 제공하여 Li-Ion 2차 전지의 수명열화를 개선하고, 열화 특성의 검토 및 개선효과 확인을 논문의 목적으로 한다.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.22 no.7
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• pp.576-579
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• 2009

This paper suggests a autonomous linear Li-ion battery charger which can safely distribute power between an external power source(AC adapter, auto adapter, or USB source), battery, and the system load. Depending on an external power source's capability, the charger selects proper charging-mode automatically. The charger IC designed and fabricated on Dongbu HITEC's $0.35{\mu}m$ BCD process with layers of one poly and three metals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.04b
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• pp.27-28
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• 2009

This paper suggests a autonomous linear Li-ion battery charger which can safely distribute power between an external power source(AC adapter, auto adapter, or USB source), battery, and the system load. Depending on an external power source's capability, the charger selects proper charging-mode automatically. The charger IC designed and fabricated on Dongbu HITEC's $0.35{\mu}m$ BCD process with layers of one poly and three metals.

• Transactions on Electrical and Electronic Materials
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• v.18 no.5
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• pp.237-245
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• 2017

A novel battery model based on the manufacturer datasheet is proposed. According to this model, not only the steady state but also the dynamic charging performance of the Li-ion battery can be analyzed and evaluated. The major advantage of our model is that all the parameters can be directly obtained from the datasheet and no additional experiments are required. Moreover, the transition between charge and discharge stages was analyzed based on our model, and a novel Simulink module was built to predict the energy consumption of a battery-powered system. Experiments were carried out to verify the model accuracy. Although the new model was developed for the Li-ion battery, it is expected to be applicable to other batteries.