High-Performance Si/SiO_<i>x</i> Nanosphere Anode Material by Multipurpose Interfacial Engineering with Black TiO_2–<i>x</i>

Bae, Juhye,Kim, Dae Sik,Yoo, Hyundong,Park, Eunjun,Lim, Young-Geun,Park, Min-Sik,Kim, Young-Jun,Kim, Hansu American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.7

<P>Silicon oxides (SiOx) have attracted recent attention for their great potential as promising anode materials for lithium ion batteries as a result of their high energy density and excellent cycle performance. Despite these advantages, the commercial use of these materials is still impeded by low initial Coulombic efficiency and high production cost associated with a complicated synthesis process. Here, we demonstrate that Si/SiOx nanosphere anode materials show much improved performance enabled by electroconductive black TiO2-x coating in terms of reversible capacity, Coulombic efficiency, and thermal reliability. The resulting anode material exhibits a high reversible capacity of 1200 mAh g(-1) with an excellent cycle performance of up to 100 cycles. The introduction of a TiO2-x layer induces further reduction of the Si species in the SiOx matrix phase, thereby increasing the reversible capacity and initial Coulombic efficiency. Besides the improved electrochemical performance, the TiO2-x coating layer plays a key role in improving the thermal reliability of the Si/SiOx nanosphere anode material at the same time. We believe that this multipurpose interfacial engineering approach provides another route toward high-performance Si-based anode materials on a commercial scale.</P>

TiO2-coated Nonstoichiometric SiO x Nanosphere for High Capacity Anode Material for Lithium Ion Batteries

Juhye Bae,김대식,Eunjun Park,박민식,김한수 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.7

Nonstoichiometric SiOx -based nanocomposites have gained considerable attention as promising anode materials for lithium-ion batteries because of their high capacity and relatively good cycle performance. However, their commercial use is still limited by some technical problems such as poor thermal reliability, dimensional stability, and safety. Herein we show that surface modification with TiO2 can effectively improve the thermal reliability of SiO x nanocomposites without sacrificing their capacity and cycle performance. We suggest that the TiO2 coating layer could significantly improve the thermal reliability of the SiO x nanocomposites. Even though the TiO2 phase introduced is less active, TiO2-coated nonstoichiometric SiO x nanocomposites showed electrochemical performance comparable with that of bare nonstoichiometric SiO x nanocomposite. We believe that the surface modification approach proposed herein will open up a new route toward high capacity Si-based anode materials for lithium-ion batteries.

여수 해만 해역의 해양 수질 및 해저 퇴적물 환경의 계절적 변동 특성

배재영(Jaeyoung Bae),한영탁(Yeongtak Han),오주혜(juhye Oh),Mai Duc Hung,조현서(Hyeonseo Cho) 한국해양환경·에너지학회 2019 한국해양환경·에너지학회 학술대회논문집 Vol.2019 No.11

Surface engineering of graphite anode material with black TiO_2-x for fast chargeable lithium ion battery

Kim, Dae Sik,Chung, Dong Jae,Bae, Juhye,Jeong, Goojin,Kim, Hansu Elsevier 2017 ELECTROCHIMICA ACTA Vol.258 No.-

<P><B>Abstract</B></P> <P>One of the most important challenges in the improvement of the lithium ion battery (LIB) for electric vehicle (EV) applications is its fast charging capability. However, currently used graphite anode materials cannot meet this requirement for EVs. Herein, we demonstrate that surface modification of graphite using oxygen-deficient black titanium oxide (TiO<SUB>2−x</SUB>) is an efficient way to improve the fast charging capability of graphite anode material for LIB. The proposed surface engineered anode material, 1 wt% TiO<SUB>2-x</SUB> coated graphite anode material, at a high rate of 5 C-rate, exhibited 98.2% of the capacity obtained at a rate of 0.2 C without any degradation of other performances. Full cell tests adopting LiCoO<SUB>2</SUB> as a cathode material with TiO<SUB>2-x</SUB> coated graphite anode material also confirmed that the TiO<SUB>2-x</SUB> coating layer can improve the fast charging capability of graphite anode material. Such an improvement in the fast charging capability has mainly been attributed to the modified interface between the anode and the electrolyte by surface-engineering of the TiO<SUB>2-x</SUB> layer on the surface of graphite. These results show that the approach presented in this work, interfacial engineering of graphite using oxygen deficient TiO<SUB>2-x</SUB>, deserves to be regarded as one of the most promising ways to develop an anode material with fast charging capability for high power LIB for EV applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Core shell structured TiO<SUB>2-x</SUB>@graphite was synthesized via sol-gel method. </LI> <LI> TiO<SUB>2-x</SUB>@graphite anode showed much improved fast charging capability. </LI> <LI> Fast charging capability of TiO<SUB>2-x</SUB>@graphite was confirmed using full cell. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A swelling-suppressed Si/SiO_<i>x</i> nanosphere lithium storage material fabricated by graphene envelopment

Yoo, Hyundong,Park, Eunjun,Kim, Hyekyoung,Bae, Juhye,Chang, Hankwon,Jang, Hee Dong,Kim, Hansu unknown 2016 Chemical communications Vol. No.

<P>A swelling-suppressed, Si nanocrystals-embedded SiOx nanospheres lithium storage material was prepared by graphene envelopment. The free void spaces formed between the graphene envelope and Si/SiOx nanospheres effectively accommodated the volume changes of Si/SiOx nanospheres during cycling, which significantly suppresses the swelling behavior and improves the capacity retention up to 200 cycles.</P>

Study of Failure Mode and Effect Analysis in Brachytherapy

Soon Sung Lee(이순성),Dong Wook Park(박동욱),Dong Oh Shin(신동오),Dong Wook Kim(김동욱),Kum Bae Kim(김금배),Yoon-Jin Oh(오윤진),Juhye Kim(김주혜),Na Hye Kwon(권나혜),Kyeong Min Kim(김경민),Sang Hyoun Choi(최상현) 한국방사선학회 2017 한국방사선학회 논문지 Vol.11 No.7

근접방사선치료는 일반적으로 외부방사선치료와 병행하여 수행되고 치료단계가 매우 복잡하며 이로 인해 방사선 사고가 발생될 수 있다. 본 연구에서는 이를 해결하기 위해 근접방사선치료에 사고유형과 영향 분석(Failure mode and effects analysis, FMEA) 방법을 적용하여 프로세스 맵을 구성하고 이를 기반으로 각 치료단계에 대한 위해도를 산출하였다. 프로세스 맵은 “외래 및 진료”와 “근접방사선 모의치료”, “CT 모의 치료”, “근접방사선치료계획”, “방사선치료”로 총 5단계로 구성하였으며, 각 치료단계를 세분화하여 세부단계를 작성하였다. 위해도를 산출하기 위해 의사와 의학물리사, 선량설계사, 방사선사, 간호사가 참여하여 세부단계마다 발생빈도와 심각도, 불검출도를 평가하였다. 전반적으로 프로세스 맵은 각 치료단계마다 환자 신원 확인 절차가 우선적으로 수행되며, 이는 다른 환자로 오인하여 서로 다른 치료계획이 수립되어 방사선사고가 발생될 우려가 있다. 프로세스 맵을 기반으로 작성한 세부단계에 대해 위해도를 평가한 결과, 전반적으로 “외래 및 진료”와 “근접방사선치료계획” 과정이 높은 위해도로 평가되었다. 직종마다 평가한 위해도는 서로 다른 경향을 보였으며, 간호사는 방사선치료를 제외한 모든 과정이 55점 이상의 위해도를 보였으며, “근접방사선 모의치료” 과정이 88.8점으로 가장 높았다. 방사선치료를 수행하는 의료기관마다 치 료단계가 다소 차이가 있으므로 해당 기관에 대한 프로세스 맵을 작성하고 위해도를 산출하여 중점관리 항목을 집중적으로 리스크 관리가 수행되어야 할 것으로 생각된다. Brachytherapy is generally performed in conjunction with external radiation therapy, and the treatment course is very complicated, which can lead to radiation accidents. In order to solve this problem, we designed the process map by applying the failure mode and effects analysis (FMEA) method to the Brachytherapy and scored the risk priority number (RPN) for each treatment course based on this process map. The process map consisted of five steps, Patient consulting , “Brachytherapy simulation , CT simulation , Brachytherapy treatment planning and Treatment . In order to calculate the RPN, doctor, medical physicist, dose planners, therapist, and nurse participated in the study and evaluated occurrence, severity, and lack of detectability at each detail step. Overall, the process map is preceded by a patient identification procedure at each treatment stage, which can be mistaken for another patient, and a different treatment plan may be established to cause a radiation accident. As a result of evaluating the RPN for the detailed steps based on the process map, overall Patient consulting and Brachytherapy treatment planning step were evaluated as high risk. The nurses showed a tendency to be different from each other, and the nurses had a risk of 55 points or more for all the procedures except Treatment , and the Brachytherapy simulation step was the highest with 88.8 points. Since the treatment stage differs somewhat for each medical institution performing radiotherapy, it is thought that the risk management should be performed intensively by preparing the process map for each institution and calculating the risk RPN.