One-step hydrothermal reduction method was used to prepare three-dimensional carbon fiber brush-based graphene–platinum (CFB/Pt–G) composites to improve the electrocatalytic oxygen reduction activity of cathode materials for seawater oxygen-dissolved battery. Characterization results show that the reduced graphene oxide of as-prepared graphene–platinum composite displays the few-layer folded structure. In addition, Pt nanoparticles with the polycrystalline structure dispplay a preferential growth along the crystal plane of (111) and are mainly distributed around the defect cavities of folded graphene. Electrochemical results show that the diffusion-limited current density of CFB/Pt–G composite tested with 1600 rpm/min in 3.5% NaCl solution reaches 5 mA/cm2, while that of CFB/G is only 2.64 mA/cm2. Battery discharge results show that the maximum volume power density of CFB/Pt–G–Mg battery with a stable open voltage of 1.73 V is 81 times as much as the commercial seawater battery SWB1200.

One disadvantage of deep cycle flooded lead-acid batteries is increasing water loss caused by use of (+) Pb-Sb / () Pb-Sb alloy grid. Water loss is generated by the emission of hydrogen gas from the () electrode during battery charging. In this paper, we maintain cycle life aspect through the development of hybrid flooded lead-acid batteries to which a (+) Pb- Sb / () Pb-Ca grid is applied and deal with the improvement of water loss. The amount of water loss compared to that of the () Pb-Sb grid decreased when Ca was added to the () Pb grid. For the () Pb-Ca grid, it was confirmed that the time to reach 0.0 V, at which water decomposition occurs, was increased compared to that of the () Pb-Sb grid at the NPV (Negative Potential Voltage). In the cycle life test conducted with the BCI (Battery Council International) standard, compared to the (+) Pb-Ca grid, the (+) Pb-Sb grid increased the life cycle of the batteries and the (+) Pb-Ca grid showed an early end of life due to PbO corrosion layer generation, as determined through SEM / EDS and Tear Down analysis. In conclusion, by addition of Sb to (+) Pb grid and Ca to () Pb grid, we developed a hybrid flooded lead-acid battery that meets user requirements to improve water loss characteristics and preserve cycle life characteristics.

Lithium-ion battery (LiB) is one of the special issues on nowadays and diverse researches to develop LiB with better performances have been carried out so far, especially, regarding improved properties of each component such as cathode, anode, separator and electrolyte. However, there are limited information on ‘processing’ to prepare each component, and especially fabrication of cathode is strongly dependent on thinky mixer to realize homogeneous dispersion of active materials and conductors in binders. Herein, we report on preparation of LiNi0.8Co0.1Mn0.1O2 (NCM811) based cathode materials with different carbon conductors (CNT and carbon black) using homogenizer and three-roll milling method. These processes are turned out perfect alternative to prepare cathode electrode. LiB cells were assembled using the dispersed electrode slurry and the performance of a cell was electrochemically stable, even in the case of a CNT conductor, which is normally difficult to make perfect dispersion because of its strong Van der Waals attraction between the tubes and π–π interactions.

목적 : 본 연구는 아동의 운동기능과 운동협응의 능력을 측정하고 운동장애의 진단을 위해 사용하고 있는 Movement Assessment Battery for Children-2(Movement ABC-2)를 국내 아동에게 적용하기 위 해 타당도와 신뢰도를 알아보고자 한 것이다. 연구방법 : 연구에 참여한 대상자는 선정기준을 만족한 총 87명을 대상으로 하였다. 타당도와 신뢰도 검증에 앞서 국외에서 개발된 Movement ABC-2의 평가지와 매뉴얼 번역을 실시하였다. 타당도는 내용타 당도와 동시타당도, 판별타당도 검증을 실시하였다. 신뢰도는 내적일치도, 검사-재검사 신뢰도 검증을 실시하였다. 결과 : 내용타당도는 평균 I-CVI가 .93으로 나타났으며, 동시타당도는 BOT-2 short form과 백분위의 상관관계를 비교한 결과 .795으로 양의 상관관계를 확인할 수 있었다. BOT-2와의 영역 간 상관관계는 조준 및 잡기(aiming & catching), 균형(balance) 영역에서 비슷한 과제가 포함된 영역 간에 유의한 양의 상관관계가 나타났다. 판별타당도는 성별, 연령별 차이를 비교한 결과, 성별에서는 모든 항목이 유의한 차이가 나타나지 않았으며, 연령별 차이에서는 ‘매트위에서 점프하기’를 제외하고 유의한 차이를 확인 할 수 있었다. 내적일치도는 Cronbach’s α 값이 .577의 수준을 보였으며, 검사-재검사 신뢰도는 .766 의 수준이었다. 결론 : 본 연구를 통해 Movement ABC-2가 국내아동에게 사용하기에 타당한 검사도구임을 검증하였으 며, 국내 치료사 및 임상가가 사용하기에 신뢰할 수 있는 도구임을 검증하였다. 이는 추후 Movement ABC-2의 다양한 활용을 기대할 수 있을 것으로 사료된다.

Tin/graphite composites are prepared as anode materials for Li-ion batteries using a dry ball-milling process. The main experimental variables in this work are the ball milling time (0–8 h) and composition ratio (tin:graphite=5:95, 15:85, and 30:70 w/w) of graphite and tin powder. For comparison, a tin/graphite composite is prepared using wet ball milling. The morphology and structure of the different tin/graphite composites are investigated using X-ray diffraction, Raman spectroscopy, energy-dispersive X-ray spectroscopy, and scanning and transmission electron microscopy. The electrochemical properties of the samples are also examined. The optimal dry ball milling time for the uniform mixing of graphite and tin is 6 h in a graphite-30wt.%Sn sample. The electrode prepared from the composite that is dry-ballmilled for 6 h exhibits the best cycle performance (discharge capacity after 50th cycle: 308 mAh/g and capacity retention: 46%). The discharge capacity after the 50th cycle is approximately 112 mAh/g, higher than that when the electrode is composed of only graphite (196 mAh/g after 50th cycle). This result indicates that it is possible to manufacture a tin/graphite composite anode material that can effectively buffer the volume change that occurs during cycling, even using a simple dry ball-milling process.

고용량 배터리에 대한 요구가 증가에 따라 기존 음극재보다 높은 용량(3,860 mAh/g)과 낮은 전기화학적 전위(– 3.040 V)를 갖는 리튬 금속 기반 음극재에 대한 연구가 활발하게 이루어지고 있다. 본 연구에서는 수열 합성을 통해 제작된 아나타제(anatase) 타입의 TiO2 나노 입자 기반한 PVdF-HFP/TiO2 복합체를 리튬 금속 음극의 계면 보호층으로 적용하였다. 결정구조 및 형상 분석을 통해 유/무기-리튬 나노복합체 박막의 형성을 확인하였다. 또한, 전지화학 테스트(사이클 테스트 및 전압 프로파일)를 통해 리튬 금속 음극의 전기화학 성능은 복합체 보호막이 TiO2 10 wt%, 코팅 두께 1.1 μm의 조건에서 가장 개선된 전기화학적 성능(콜롱 효율 유지: 77 사이클 동안 90% 이상) 발현을 확인하였다. 이를 통해, 처리하지 않은 리튬 전극 대비 본 보호층에 의한 리튬 금속 음극의 성능 안정화/개선 효과가 검증되었다.

The high level of lithium storage in synthetic porous carbons has necessitated the development of accurate models for estimating the specific capacity of carbon-based lithium-ion battery (LIB) anodes. To date, various models have been developed to estimate the storage capacity of lithium in carbonaceous materials. However, these models are complex and do not take into account the effect of porosity in their estimations. In this paper, a novel model is proposed to predict the specific capacity of porous carbon LIB anodes. For this purpose, a new factor is introduced, which is called normalized surface area. Considering this factor, the contribution of surface lithium storage can be added to the lithium stored in the bulk to have a better prediction. The novel model proposed in this study is able to estimate the lithium storage capacity of LIB anodes based on the porosity of porous carbons for the first time. Benefiting porosity value (specific surface area) makes the predictions quick, facile, and sensible for the scientists and experts designing LIBs using porous carbon anodes. The predicted capacities were compared with that of the literature reported by experimental works. The remarkable consistency of the measured and predicted capacities of the LIB anodes also confirms the validity of the approach and its reliability for further predictions.

대기오염물질 감축에 대한 국제적인 인식이 높아짐에 따라 친환경 선박에 대한 수요가 증가하고 있어 각국에서 전기추진선박 개발을 활발하게 수행하고 있다. 현재 전기추진선박에 대해서는 주로 전기추진시스템 및 전동기 연구를 주로 수행하고 있으며, 선박 관점 에서 전기추진시스템 및 배터리의 탑재를 고려한 국내 연안 차도선 개념설계 연구는 수행된 바가 없다. 본 연구에서는 배터리 차량 기반의 이동식 전원공급시스템을 주전원으로 하는 순수전기추진차도선의 개념설계 과정에서의 주요 고려사항에 대하여 검토하였다. 100척 이상의 국내 연안차도선의 제원을 분석하여, 요구사항 만족을 위한 선박의 주요제원 선정과 이동식 배터리 차량 탑재를 고려한 비손상, 손상 복원성능 검토를 수행하였고, 개념설계 과정에서 발생하는 문제의 원인분석을 통해 해결방안을 모색하였다.

The enhancement of heat transfer in cooling system of cylindrical lithium-ion battery pack is numerically investigated by installing fins on the cooling plate. Battery Design StudioⓇ software is used for modeling electro-chemical heat generation in the battery and the conjugated heat transfer is analyzed with the commercial package STAR-CCM+. The result shows that installing fins on the cooling plate increases the convective heat transfer on the surface and thus lowers the maximum temperature of the battery pack. As the length and thickness of the fins increase, heat transfer in the battery pack improves. Considering the geometry and airflow of the battery pack, the optimal values for the length and thickness of the fin are both 2mm. As the convective heat transfer coefficient of the surface increases, the maximum temperature of the battery pack is greatly reduced and the temperature gradient is greatly improved.

전 바나듐 레독스 흐름 전지(VRFB)는 유망한 대용량 에너지 저장 기술 중 하나이다. 이온교환막은 VRFB의 충⋅ 방전 성능 및 내구성을 좌우하는 핵심 구성 요소이다. 본 연구에서는 기존 탄화수소계 이온교환막의 단점을 보완하기 위해 우수한 물리적 및 화학적 안정성을 갖는 다공성 폴리테트라플루오로에틸렌(PTFE) 지지체의 세공에 불소부가 포함된 탄화수 소계 이오노머를 충진하는 방식으로 세공충진 음이온교환막(PFAEMs)을 제조하였다. 얇은 다공성 PTFE 지지체의 사용으로 전기적 저항을 현저히 낮출 수 있었으며 PTFE 지지체의 사용과 더불어 충진 이오노머에 불소부를 도입함으로써 막의 산화 안정성을 크게 향상시킬 수 있었다. 충⋅방전 성능 평가 결과, PFAEM에 불소부의 함량이 증가할수록 높은 전류 효율을 나타내었으며 낮은 전기적 저항으로 상용막 대비 우수한 전압 효율 및 에너지 효율을 보였다. 또한, 산화 안정성 및 충⋅방전 성능의 관점에서 소수성 PTFE 지지체의 사용이 더 바람직함을 확인하였다.

메타바나듐산 암모늄으로 제조한 전해액과 양이온교환막인 Nafion117을 활용하는 바나듐 레독스 흐름 전지 (vanadium redox flow battery, VRFB)의 전기화학적 성능을 평가하였다. VRFB의 전기화학적 성능은 전류밀도 60 mA/cm2에 서 측정하였다. 메타바나듐산 암모늄으로 제조된 전해액을 사용한 VRFB의 평균 전류효율은 94.9%, 평균 전압효율은 82.2%, 평균 에너지효율은 78.0%를 보였다. 그리고 메타바나듐산 암모늄으로 제조된 전해액을 사용한 VRFB의 각 효율은 바나딜 설 페이트(VOSO4)로 제조된 전해액을 사용한 VRFB의 각 효율과 비교하여 거의 동등한 값을 갖는다는 것을 확인하였다.

Morphology control of a graphene nanosheet (GNS) is important for graphene-based battery electrodes to exhibit the increased practical surface area and the enhanced ion diffusion into the nanosheets. Nevertheless, it is very difficult to minutely control the shape of graphene nanosheets based on the conventional GNS suspension methods. In this work, we fabricated wrinkle textures of free-standing GNS for large area using Langmuir–Schaefer technique. The wrinkles are oriented vertically to the direction of the monolayer compression. The textured structure of GNS was obtained by cross-deposition of each layer with controlling the orientation of the wrinkle direction. These wrinkles can cause Li-ion to diffuse into the voids created by them and raise the specific surface area between the GNSs. Consequently, as a prospective anode for Li-ion battery, the wrinkled GNS multilayer, exhibits the high specific capacity of ~ 740 mAh g− 1 at 100 mA g−1 and the great power capability with ~ 404 mAh g− 1 being delivered even at 2 A g− 1. Furthermore, outstanding cycle performance of the wrinkled GNS multilayer is achieved over 200 cycles at 300 mA g−1 with high Coulombic efficiency of ~ 96%.

To cope with automobile exhaust gas regulations, ISG and charging control systems are applied to HEV vehicles for the purpose of improving fuel economy. These systems require quick charge-discharge performance of high current. Therefore, a Module of the AGM battery with high energy density and EDLC(Electric Double Layer Capacitor) with high power density are constructed to study the charging and discharging behavior. In CCA, which evaluates the starting performance at -18 oC & 30 oC with high current, EDLC contributed for about 8 sec at the beginning. At 0 oC CA (Charge Acceptance), the initial Charging current of the AGM/EDLC Module, is twice that of the AGM lead acid battery. To play the role of EDLC during high-current rapid charging and discharging, the condition of the AGM lead-acid battery is optimally maintained. As a result of a Standard of Battery Association of Japan (SBA) S0101 test, the service life of the Module of the AGM Lead Acid Battery/EDLC is found to improve by 2 times compared to that of the AGM Lead Acid Battery.

To cope with automobile exhaust gas regulations, ISG (Idling Stop & Go) and charging control systems are applied to HEVs (Hybrid Electric Vehicle) for the purpose of improving fuel economy. These systems require quick charge/discharge performance at high current. To satisfy this characteristic, improvement of the positive electrode plate is studied to improve the charge/discharge process and performance of AGM(Absorbent Glass Mat) lead-acid batteries applied to ISG automotive systems. The bonding between grid and A.M (Active Material) can be improved by applying the Sand-Blasting method to provide roughness to the surface of the positive grid. When the Sand-Blasting method is applied with conditions of ball speed 1,000 rpm and conveyor speed 5 M/min, ideal bonding is achieved between grid and A.M. The positive plate of each condition is applied to the AGM LAB (Absorbent Glass Mat Lead Acid Battery); then, the performance and ISG life characteristics are tested by the vehicle battery test method. In CCA, which evaluates the starting performance at -18 oC and 30 oC with high current, the advanced AGM LAB improves about 25 %. At 0 oC CA (Charge Acceptance), the initial charging current of the advanced AGM LAB increases about 25 %. Improving the bonding between the grid and A.M. by roughening the grid surface improves the flow of current and lowers the resistance, which is considered to have a significant effect on the high current charging/discharging area. In a Standard of Battery Association of Japan (SBA) S0101 test, after 300 A discharge, the voltage of the advanced AGM LAB with the Sand-Blasting method grid was 0.059 V higher than that of untreated grid. As the cycle progresses, the gap widens to 0.13 V at the point of 10,800 cycles. As the bonding between grid and A.M. increases through the Sand Blasting method, the slope of the discharge voltage declines gradually as the cycle progresses, showing excellent battery life characteristics. It is believed that system will exhibit excellent characteristics in the vehicle environment of the ISG system, in which charge/discharge occurs over a short time.

In this study, soybean oil, which is used in a large variety of processed foods, is used as a carbon source. Soybean oil is successfully coated onto the surface of LiNi1/ 3Co1/3Mn1/3O2 (NCM) by a simple method. The physical and electrochemical properties of NCM/C hybrid materials are determined. As a result, a 5 nm thickness carbon coating layer is formed on the surface of the NCM, resulting in improved capability and cyclic performance in the battery. The NCM/C battery shows an initial discharge capacity of 159 mAh g−1 and 95% capacity retention after 100 cycles (a discharge capacity of 120 mAh g−1 and 94% retention are observed after 100 cycles for the NCM cathode).