• Journal of the Korean Applied Science and Technology
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• v.32 no.4
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• pp.718-723
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• 2015

For the fabrication of the Si negative electrode in Li-ion batteries (LIBs) containing the cross-linking polymer binder, in this work, the urethane acrylate (UA) oligomer was synthesized via a simple synthetic process. The cross-linked poly(urethane acrylate) (CPUA)/carbone black (CB)/Si composite (CPUA/CB/Si composite) was fabricated through reactions between their reactive vinyl segments in the UA oligomer. Interestingly, the CPUA/CB/Si composite showed better cycle performance than the poly(vinylidene fluoride) (PVdF)/CB/Si composite (PVdF/CB/Si composite) and the polyurethane (PU)/CB/Si composite (PU/CB/Si composite). The CPUA/CB/Si composite had the best lithiation of about $2586mAh\;g^{-1}$. The UA oligomer showed a good compatibility with the electrode materials and current collector after and before a curing process.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.420-421
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• 2010

In this paper, a multi-module selective battery equalizer for series-connected Li-ion battery pack is proposed. Selective Equalizer (SE) scheme achieves smaller volume and lighter weight than individual cell equalizer (ICE) by minimizing the part count of bulky circuit element. However, SE scheme shows slow balancing speed when the voltage imbalance simultaneously occurs in more than one cell. The proposed multi-module overcomes the problem by employing multiple power converters. Prototype hardware is implemented and experimented with 14Ah battery cells to validate the performance of the proposed equalizer.

• Journal of Power Electronics
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• v.18 no.3
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• pp.910-922
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• 2018

Conventional battery state-of-charge (SoC) estimation methods either involve sophisticated models or consume considerable computational resource. This study constructs an enhanced coulomb counting method (Ah method) for the SoC estimation of lithium-ion batteries (LiBs) by expanding the Peukert equation for the discharging process and incorporating the Coulombic efficiency for the charging process. Both the rate- and temperature-dependence of battery capacity are encompassed. An SoC mapping approach is also devised for initial SoC determination and Ah method correction. The charge counting performance at different sampling frequencies is analyzed experimentally and theoretically. To achieve a favorable compromise between sampling frequency and accumulation accuracy, a frequency-adjustable current sampling solution is developed. Experiments under the augmented urban dynamometer driving schedule cycles at different temperatures are conducted on two LiBs of different chemistries. Results verify the effectiveness and generalization ability of the proposed SoC estimation method.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.71.2-71.2
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• 2012

There are rising demands for developing more efficient energy materials to stem the depletion of fossil fuels, which have prompted significant research efforts on proton exchange fuel cells (PEFCs) and lithium ion batteries (LIBs). To date, both PEFCs and LIBs are being widely developed to power small electronics, however, their utilization to medium-large sized electric power resources such as vehicle and stationary energy storage systems still appears distant. These technologies increasingly rely upon polymer electrolyte membranes (PEMs) that transport ions from the anode to the cathode to balance the flow of electrons in an external circuit, and therefore play a central role in determining the efficiency of the devices; as ion transport is a kinetic bottleneck compared to electrical conductivity, enormous efforts have been devoted to improving the transport properties of PEMs. In present study, we carried out an in-depth analysis of the morphology effects on transport properties of PEMs. How parameters such as self-assembled nanostructures, domain sizes, and domain orientations affect conductivities of PEMs will be presented.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.16-19
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• 2016

More efficient use of the battery pack is dependent upon how to measure the remaining capacity of the battery accurately. Among various measurement methods, the basic correction measurement method has still been a hot research topic area to reduce the errors. In this paper, the problems of the existing methods have been investigated and the research direction for measuring more accurate remaining capacity has been suggested by applying the numerical simulations in the future.

• Journal of the Semiconductor & Display Technology
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• v.15 no.2
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• pp.20-25
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• 2016

The parallel computer cluster system has been known as the powerful tool to solve a complex physical phenomenon numerically. The numerical analysis of large size of Li-ion battery pack, which has a complex physical phenomenon, requires a large amount of computing time. In this study, the numerical analyses were conducted for comparing the computing efficiency between the single workstation and the parallel cluster system both with multicore CPUs'. The result shows that the parallel cluster system took the time 80 times faster than the single work station for the same battery pack model. The performance of cluster system was increased linearly with more CPU cores being increased.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.351-351
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• 2008

리튬이차전지 산업의 눈부신 발전과 이에 의한 편리함의 이면에는 아직도 안전성 개선이라는 중요한 문제가 있다. 이에, 난연성 물질로 알려진 트리아진 유도체들을 전해액의 첨가제로 사용하여, 전지의 안전성 개선여부를 알아보았다. 전기화학적, 열적분석을 통하여 첨가제가 전지 성능에 미치는 영향과 열적안전성 개선에 대해서 토의하고자한다.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.69-71
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• 2018

기존 전기자전거의 경우에 사용되는 일반 배터리팩 방식에 비해 이중 배터리 팩 (Li-ion Batterty + Super Capacitor)의 방식이 동등 주행 성능 및 지속 시간 조건에서 무게 및 원가 저감이 가능하다. 또한 기존 승압형 Converter인 Boost Converter는 이중 배터리를 이용시 큰 inrush 전류를 발생시키고 이 전류로 인해 소자 파손에 문제가 있다. 따라서 본 논문에서는 입력 전압을 Li-ion Battery로, 출력 전압에 Super Capacitor를 연결하는 이중 배터리로 구성되고 기존 Boost converter 입력단에 Mosfet과 Diode를 추가하여 inrush 전류가 발생하지 않게 한다. 본 논문에서는 제안된 회로의 이론적 특성을 분석하고 실험을 통해 타당성을 검증하였다.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.265-270
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• 2013

Dialysis is the rate-limiting step in the preparation of aqueous silk fibroin (SF) solution. However, the traditional practice of dialyzing SF solution for at least 48 h to remove LiBr is not based on empirical evidence. The aim of the present study was to systematically measure LiBr content in SF solutions dialyzed for varying lengths of time and assess the potential toxicity of residual lithium ions in cells. Complete removal of lithium ions was not achieved even after 72 h of dialysis, with a residual lithium ion content in the solution of 22.85 mg/l. SF films prepared from solutions dialyzed for 8 and 24 h had predominantly random coil or b-sheet structures, respectively. The residual lithium had little cytotoxicity in NIH3T3 fibroblast cells, but viability was compromised in cells grown on SF film prepared from solution dialyzed for 24 h.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2002.12a
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• pp.410-413
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• 2002

일반적으로 휴대폰에는 리튬이온(Ll-lon) 전지(battery)를 많이 사용하고 있으며 그 전지(battery)를 충전시키기 위해 Microcontroller를 사용해서 과충전과 방전, 그리고 전지(battery) 보호와 충전에 대한 일정한 전류를 제어한다. 여기에서 충전 동작 시 필요한 일반직인 충전 전류 제어를 PWM의 방식에 의존하지 않고 인공지능 기법을 이용해 소프트웨어적으로 처리가 필요한 파라메터 값을 추정해 적용시키고자 한다. 따라서 개발한 충전시스템에 일반적인 충전 파라메터를 전압과 전류 그리고 시간으로 분류하여 Microcontroller에 그 파라메터를 적용시켜 PWM 방식으로 제어한 후에 실험에 의한 결과값을 얻는다. 그리고 이것들을 비교하여 보다 나은 충전시스템을 구현하기 위해 인공지능 기법 중에 하나인 신경망을 이용하여 전압과 전류 그리고 시간에 대한 파라메터를 처리하였다. 본 논문에서 신경망에 대한 파라메터의 학습을 일반 FC에서 구현하고 여기에서 추출된 학습 값을 Microcontroller에 적용시켜 입력값에 따라 다양한 PWM 신호를 발생시키도록 구현했다. 이후 실제적인 실험에 의한 결과값을 본 논문에서 서술하였다.