• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.347-350
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• 2000

The purpose of this study is to research and develop solid polymer electrolyte(SPE) for Li polymer battery. The temperature dependence of conductivity, impedance spectroscopy and electrochemical properties of PMMA/PVDF electrolytes as a function of a mixed ratio were reported for PMMA/PVDF based polymer electrolyte films, which were prepared by thermal gellification method of preweighed PMMA/PVDF, plasticizer and Li salt. The ion conductivity of PMMA/PVDF electrolytes was 10$\^$-3/S/cm, which may be applicable to a constituent of lithium secondary battery. 5PMMA20PVDFLiC1O$_4$PC$\sub$8/EC$\sub$8/ electrolyte remains stable up to 5V vs. Li/Li$\^$+/. Steady state current method and AC impedance were used for the determination of transference numbers in PMMA/PVDF electrolyte film. The transference number of 5PMMA20PVDFLiC1O$_4$PC$\sub$8/EC$\sub$8/ electrolyte is 0.55.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.12
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• pp.1033-1038
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• 2002

In this study, urethane acrylate macromer was synthesized and it was used in a gel polymer electrolyte (GPE), and then its electrochemical performances were evaluated. LiCoO$_2$/GPE/graphite cells were Prepared and their performances depending on discharge currents and temperatures were evaluated. The precursor consisting of urethane acrylate (UA), hexanediol dimethacrylate (HDDA) and benzoyl peroxide (BPO) had a low viscosity relatively ionic conductivity of the gel polymer electrolyte with UA at room temperature and -20$\^{C}$ was ca. 4.5 $\times$ 10$\^$-3/S$.$cm$\^$-1/ and 1.7 x 10$\^$-3/ S$.$cm$\^$-1/, respectively GPR was stable electrochemically up to potential of 4.i V vs. Li/Li$\^$+/. LiCoO$_2$/GPE/graphite cells showed good a high-rate and a low-temperature performance.

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.362-368
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• 2022

The application of polymer composite electrolyte in all-solid-state lithium-sulfur battery (ASSLSBs) can guarantee high energy density and improve the interface contact between electrolyte and electrode, which has a broader application prospect. However, the inherent insulation of the sulfur-cathode leads to a low electron/ion transfer rate. Carbon materials with high electronic conductivity and electrolyte materials with high ionic conductivity are usually selected to improve the electron/ion conduction of the composite cathode. In this work, PEO-LiTFSI-LLZO composite polymer electrolyte (CPE) with high ionic conductivity was prepared. The ionic conductivity was 1.16×10^-4 and 7.26×10^-4 S cm^-1 at 20 and 60℃, respectively. Meanwhile, the composite sulfur cathode was prepared with Sulfur, reduced graphene oxide and composite polymer electrolyte slurry (S-rGO-CPEs). In addition to improving the ion conductivity in the cathode, CPEs also replaces the role of binder. The influence of different contents of CPEs in the cathode material on the performance of the constructed battery was investigated. The results show that the electrochemical performance of the all-solid-state lithium-sulfur battery is the best when the content of the composite electrolyte in the cathode is 40%. Under the condition of 0.2C and 45℃, the charging and discharging capacity of the first cycle is 923 mAh g^-1, and the retention capacity is 653 mAh g^-1 after 50 cycles.

• Journal of the Korean institute of surface engineering
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• v.54 no.5
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• pp.213-221
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• 2021

In order to improve the energy density and safety of Li-ion batteries, the development of a separator with high thermal stability and electrolyte wettability is an important desire. Thus, the ceramic separator to replace the polymer type is one of the most promising materials that can prevent short-circuit caused by the formation of dendrite and thermal deformation. In this study, we introduce the fabrication of various anodic aluminum oxide membranes for the application of Li-ion battery separators with the advantages of improved mechanical/thermal stability, wettability, and a high rate of Li⁺ migration through the membrane. Two different types of through-holes and branched anodic aluminum oxide membranes are well used in lithium-ion battery separators, however, branched anodic aluminum oxide membranes exhibit the most improved performance with capacity (126.0 mAh g^-1 @ 0.3C), capacity drop at the high C-rate (30.6 %), and low internal resistance (8.2 Ω).

• Fire Science and Engineering
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• v.30 no.2
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• pp.114-122
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• 2016

This study is to analyze the explosion and fire risks due to high temperature and short circuit current of Lithium batteries. This study selected the typical types of Li-polymer batteries and Li-ion batteries as the test samples. The result of explosion risk assessment due to the high temperature showed that, while a Li-polymer battery had $170^{\circ}C$ explosion on average, a Li-ion battery had $187^{\circ}C$ explosion. The measurement result of temperature increase due to short circuit current revealed that, in case that protection circuit module (PCM) was normally working, there was little of temperature increase due to over-current limitation. However, in case that PCM was out of order, the temperature of a Li-polymer battery increased up to an average of $115.7^{\circ}C$ and the temperature of a Li-ion battery increased up to an average of $80.5^{\circ}C$, which showed the higher risks of fire and burn.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.909-910
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• 2013

• Bulletin of the Korean Chemical Society
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• v.35 no.2
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• pp.357-364
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• 2014

Size controlled, $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ cathode powders were prepared by co-precipitation method followed by heat treatment at temperatures between 750 and $850^{\circ}C$. The synthesized samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical performance. The synthesized $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ has a good electrochemical performance with an initial discharge capacity of $190mAhg^{-1}$ and good capacity retention of 100% after 30 cycles at 0.1C ($17mAg^{-1}$). The capacity retention of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ after calcined at $750^{\circ}C$ is better than that at 800 and $850^{\circ}C$ without capacity loss at various high C rates. This is ascribed to the minimized cation disorder, a higher conductivity, and higher lithium ion diffusion coefficient ($D_{Li}$) observed in this material. In the differential scanning calorimetry DSC profile of the charged sample, the generation of heat by exothermic reaction was decreased by calcined at high temperature, and this decrease is especially at $850^{\circ}C$. This behavior implies that the high temperature calcinations of $LiNi_{0.8}Co_{0.15}Al_{0.05}O_2$ prevent phase transitions with the release of oxygen.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.2
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• pp.162-168
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• 2002

The purpose of this study is to research and develop LiMnO$_2$-organic and Li$_{0.3}$MnO$_{2}$-organic composite with high energy density for Lithium ion polymer battery. This paper describes cyclic voltammetry, impedance sepctroscopy, electrochemical properties of LiMnO$_2$-organic and Li$_{0.3}$MnO$_{2}$-organic composite with polymer electrolyte as a function of a mixed ratio. The first discharge capacity of LiMnO$_2$-PAn with 3 wt.% PAn was 83mHA/g, while that of Li$_{0.3}$MnO$_{2}$-PPy composite was 136 mAh/g. The Ah efficiency was above 98% after the 2nd cycle. The LiMnO$_2$-PAn with DMcT 2 wt.% and Li$_{0.3}$MnO$_{2}$-PPy composites cathode with 5wt. PPy in PVDF-PC-EC-LiClO$_4$ electrolyte showed good capaity with cycling. The discharge capacity of LiMnO$_2$-PAn with wt.% DMcT was 80 and 130 mAh/g at 1st and 12th cycle, respectively. The capacity of LiMnO$_2$-PAn composite with 2 wt.% DMcT was higher than that of LiMnO$_2$-PAn composite.mposite.

• Proceedings of the KIPE Conference
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• 2014.11a
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• pp.70-71
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• 2014

In this paper, an advanced charging strategy for improving the charging performance of the Li-ion polymer battery is proposed, which is based on the battery characteristic. Simulation results show that the proposed charging current pattern can improve the charging speed of battery in comparison with the standard CC-CV (constant current - constant voltage) charging strategy and the pulse-charging strategy.

• Journal of Electrochemical Science and Technology
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• v.13 no.3
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• pp.339-346
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• 2022

Silicon (Si) has attracted considerable attention due to its high theoretical capacity compared to conventional graphite anode materials. However, Si-based anode materials suffer from rapid capacity loss due to mechanical failure caused by large volume change during cycling. To alleviate this phenomenon, crosslinked polymeric binders with strong interactions are highly desirable to ensure the electrode integrity. In this study, thermally crosslinked polyimide binders were used for Si-alloy anodes in Li-ion batteries. The crosslinked polyimide binder was found to have high adhesion strength, resulting in enhanced electrode integrity during cycling. Therefore, the Si-alloy anodes with crosslinked polyimide binder provide enhanced electrochemical performance, such as Coulombic efficiency, capacity retention, and cycle stability.