• Journal of the Korean Electrochemical Society
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• v.1 no.1
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• pp.28-32
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• 1998

The electrochemical behavior of film and charge-discharge capacity of Li-ion cell in 1 M $LiPF_6/EC:DME$ (1 : 1, by volume ratio) electrolyte solution was studied using chronopotentiometry, cyclic voltammetry, chronoamperometry, and impedance spectroscopy. The first irreversible capacity was higher than the second irrversible capacity because of solvent decomposition. Especially, passivation film that is electron insulating and ionic conducting were formed on the MPCF by solvent decomposition during the first charge. The solvated Li is co-intercalated with solvent into MPCF electrode. Part of the MPCF is expoliated during co-intercalation of solvent-Li. The MPCF ends up nonuniformly covered by a relatively thick layer of exfoliated particles embedded in a matrix of product by solvent decomposition.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.4
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• pp.305-311
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• 2017

In this paper, the LLC resonant converter battery charger, using adaptive turn ratio scheme, is proposed to achieve high efficiency and wide range output voltage. The LLC converter high frequency transformer has an adaptively changed turn ratio by the auxiliary control circuitry. As a result, the optimal converter design with a large magnetizing inductance is easily achieved to minimize the conduction and the turn-off losses while providing widely regulated voltage gain capability to properly charge the Li-ion battery. The proposed converter operational principle and the optimal design considerations are illustrated in detail. Finally, several simulation results verify the proposed LLC resonant converter's effectiveness.

• Polymer(Korea)
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• v.26 no.1
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• pp.45-52
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• 2002

The separator made from the blends of high density polyethylene (HDPE) and ultrahigh molecular weight polyethylene (UHMWPE) was prepared by wet processing to use as Li-ion secondary battery. We investigated effects of the blending of the polymers and the film extension on the mechanical properties of the separator. The mechanical strength of separator increased with increasing molecular weights and contents of UHMWPE, for instance about $1000 kg/\textrm{cm}^2$ with the five times extended film of 6 wt% UHMWPE. The pores of the separator were very uniform with the size of 0.1~$0.12\mu\textrm{m}$. The shut-down characteristic quickly increased at around $130^{\circ}C$ and the fusion temperature was $160^{\circ}C$, so it could be applied to the lithium ion secondary battery.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.430-435
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• 2017

$Li_4Ti_5O_{12}$ (LTO) is an anode material for lithium ion battery, and the cycle performance is very good. The volume change of LTO during insertion and deinsertion of lithium ion is very small, so the cyclibility is very high. In this experiment graphene and CNT was added to increase the low conductivity of LTO which is the weak point of LTO. When graphene was located on the surface of LTO the conductivity did not increase so much because of the nano size LTO. Addition of CNT increased the conductivity because of the formation of the conducting network between LTO particle and the graphene. Carbon material addition was changed before and after the LTO manufacturing, and the capacity and the cyclibility was compared.

• Carbon letters
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• v.8 no.4
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• pp.335-339
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• 2007

Carbon/silicon composites were synthesized by mixing silicon powders with petroleum pitch and subsequent heat-treatment. The resultant composites were composed of carbon and nano-size crystalline silicon identified by XRD and EDX. FIB images and SEM images were taken respectively to detect the existence of silicon impregnated in carbon and the distribution of silicon on the carbon surface. The obtained carbon/silicon materials were assembled as half cell anodes for lithium ion secondary battery and their electrochemical properties were tested. The pitch/silicon composite (3 : 1 wt. ratio) heat treated at $1000^{\circ}C$ and mixed with 55.5 wt.% of graphite showed relatively good electrochemical properties such as the initial efficiency of 78%, the initial discharge capacity of 605 mAh/g, and the discharge capacity of 500 mAh/g after 20 cycles.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.11-15
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• 2017

Lithium-ion batteries are widely used, from lightweight to energy-intensive, from small devices to large ESSs. However, it is sensitive to the surrounding environment and there is a change in performance depending on the temperature change. In this study, the temperature dependence of the charge / discharge characteristics of the battery is shown through simulation and the distribution of the salt concentration in the electrolyte is observed when the sudden temperature change is applied.

• Transactions of Materials Processing
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• v.32 no.3
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• pp.136-144
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• 2023

This study analyzed the mechanical behavior of lithium-ion battery pouch material and predicted its formability. A homogenization method was used to evaluate the physical properties of the pouch, and a new hardening model was developed. The yield function for the plastic model was optimized, and the anisotropic property was determined. Also, the forming limits were measured and predicted using the M-K forming limit diagram. Finally, a square cup drawing experiment confirmed the accuracy of the measured mechanical properties and the formability calculation.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.5-12
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• 1999

By the PVA-precursor method, polycrystalline powder of $Li_xNi_{1-y}Co_yO_2$, cathode material for lithium battery, was synthesized. Using the powder as the cathode material, lithium ion batteries were fabricated, whose electrochemical properties were measured. The effect of changing synthetic conditions, such as PvA/metal mole ratio, concentration of PVA, degree of polymerization of PVA, pyrolysis condition, and metal stoichiometry, on the battery performance was investigated. Considering the initial performance of the cell, the optimum stoichiometry of the $Li_xNi_{1-y}Co_yO_2$, synthesized by the PVA-precursor method was observed to be x: 1.0 and y=0.26. A minor phase of $Li_2CO_3$, which was generated by the residual carbon in the powder precursor, deteriorated the performance of the cell. In order to eliminate the minor phase, the precursor had to be pyrolyzed under the flow of dry air. Annealing the powder at $500^{\circ}C$ under the flow of dry air also eliminated the minor phase, and the performance of the cell was largely improved by the treatment.

• Clean Technology
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• v.21 no.4
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• pp.265-270
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• 2015

In order to increase the capacity of the lithium ion battery, the capacity of the anode should be increased. SnO₂ and Li₄Ti₅O₁₂ were studied to replace the graphite as the anode materials. In this study, SnO₂/Li₄Ti₅O₁₂ composite materials were synthesized by solid-state method. The study reported here attempts to enhance the electrochemical capacity of Li₄Ti₅O₁₂ through the incorporation of SnO₂. Sn-based Li ion storage materials are loaded on Li₄Ti₅O₁₂ surface. The SnO₂/Li₄Ti₅O₁₂ composite material has higher capacity than Li₄Ti₅O₁₂, but the cycling capacity was decreased due to SnO₂.

• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2698-2700
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• 2010