• Title/Summary/Keyword: Discharging Performance

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Thermally Conductive Polymer Composites for Electric Vehicle Battery Housing (전기자동차 배터리 하우징용 열전도성 고분자 복합재료)

  • Yoon, Yeo-Seong;Jang, Min-Hyeok;Moon, Dong-Joon;Jang, Eun-jin;Oh, Mee-Hye;Park, Joo-Il
    • Journal of the Korea Convergence Society
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    • v.13 no.4
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    • pp.331-337
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    • 2022
  • Manufactured thermoplastic composite materials to replace the metal materials used as battery housing materials for electric vehicles with lightweight materials. As the matrix material, nylon 6 which is a polymer material was used. Boron Nitrate(BN), which has high thermal conductivity, was used to provide heat dissipation performance. The heat dissipation characteristics of the thermally conductive polymer composite material according to the BN content and particle size were analyzed. The thermal conductivity value increased as the filler content increased, and composite materials particle size of 60 to 70㎛ and BN content of 50%, the thermal conductivity was 1.4 W/mK. The larger the particle size, the wider the inter-particle interface contact surface, which means that a thermal path was formed. wider the interfacial contact surface between the particles, and the thermal path was formed. A battery housing was manufactured using the manufactured thermally conductive polymer composite material, and the temperature change during charging and discharging of the cell was observed, and the possibility as a substitute material for the battery housing was confirmed.

Nanofibers Comprising Mo2C/Mo2N Nanoparticles and Reduced Graphene Oxide as Functional Interlayers for Lithium-Sulfur Batteries (Mo2C/Mo2N 나노 입자와 환원된 그래핀 옥사이드가 복합된 나노 섬유 중간층이 적용된 리튬-황 전지)

  • Lee, Jae Seob;Yang, Ji Hoon;Cho, Jung Sang
    • Korean Chemical Engineering Research
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    • v.60 no.4
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    • pp.574-581
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    • 2022
  • Nanofibers comprising reduced graphene oxide (rGO) and Mo2C/Mo2N nanoparticles (Mo2C/Mo2N rGO NFs) were prepared for a functional interlayer of Li-S batteries (LSBs). The well-dispersed Mo2C and Mo2N nanoparticles in the nanofiber structure served as active polar sites for efficient immobilization of dissolved lithium polysulfide. The rGO nanosheets in the structure also provide conductive channels for fast ion/electron transport during charging-discharging and ensured reuse of lithium polysulfide during redox reactions through a fast charge transfer process. As a result, the cell assembled with Mo2C/Mo2N rGO NFs-coated separator and pure sulfur electrode (70 wt% of sulfur content and 2.1 mg cm-2 of sulfur loading) showed a stable discharge capacity of 476 mA h g-1 after 400 charge-discharge cycles at 0.1 C. Furthermore, it exhibited a discharge capacity of 574 mA h g-1 even at a high current density of 1.0 C. Therefore, we believe that the proposed unique nanostructure synthesis strategy could provide new insights into the development of sustainable and highly conductive polar materials as functional interlayers for high performance LSBs.

The Study for EV Charging Infrastructure connected with Microgrid (마이크로그리드와 연계된 전기자동차 충전인프라에 관한 연구)

  • Hun Shim
    • Journal of Internet of Things and Convergence
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    • v.10 no.1
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    • pp.1-6
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    • 2024
  • In order to increase the use of electric vehicles (EVs) and minimize grid strain, microgrid using renewable energy must take an important role. Microgrid may use fossil fuels such as small diesel power, but in many cases, they can be supplied with energy from renewable energy, which is an eco-friendly energy source. However, renewable energy such as solar and wind power have variable output characteristics. Therefore, in order to meet the charging and discharging energy demands of electric vehicles and at the same time supply load power stably, it is necessary to review the configuration of electric vehicle charging infrastructure that utilizes diesel power or electric vehicle-to-grid (V2G) as a parallel energy source in the microgrid. Against this background, this study modelized a microgrid that can stably supply power to loads using solar power, wind power, diesel power, and V2G. The proposed microgrid uses solar power and wind power generation as the primary supply energy source to respond to power demand, and determines the operation type of the load's electric vehicles and the rotation speed of the load synchronous machine to provide stable power from diesel power for insufficient generations. In order to verify the system performance of the proposed model, we studied the stable operation plan of the microgrid by simulating it with MATLAB /Simulink.

Recent Progress in Air-Conditioning and Refrigeration Research : A Review of Papers Published in the Korean Journal of Air-Conditioning and Refrigeration Engineering in 2016 (설비공학 분야의 최근 연구 동향 : 2016년 학회지 논문에 대한 종합적 고찰)

  • Lee, Dae-Young;Kim, Sa Ryang;Kim, Hyun-Jung;Kim, Dong-Seon;Park, Jun-Seok;Ihm, Pyeong Chan
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.29 no.6
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    • pp.327-340
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    • 2017
  • This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2016. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of flow, heat and mass transfer, the reduction of pollutant exhaust gas, cooling and heating, the renewable energy system and the flow around buildings. CFD schemes were used more for all research areas. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results of the long-term performance variation of the plate-type enthalpy exchange element made of paper, design optimization of an extruded-type cooling structure for reducing the weight of LED street lights, and hot plate welding of thermoplastic elastomer packing. In the area of pool boiling and condensing, the heat transfer characteristics of a finned-tube heat exchanger in a PCM (phase change material) thermal energy storage system, influence of flow boiling heat transfer on fouling phenomenon in nanofluids, and PCM at the simultaneous charging and discharging condition were studied. In the area of industrial heat exchangers, one-dimensional flow network model and porous-media model, and R245fa in a plate-shell heat exchanger were studied. (3) Various studies were published in the categories of refrigeration cycle, alternative refrigeration/energy system, system control. In the refrigeration cycle category, subjects include mobile cold storage heat exchanger, compressor reliability, indirect refrigeration system with $CO_2$ as secondary fluid, heat pump for fuel-cell vehicle, heat recovery from hybrid drier and heat exchangers with two-port and flat tubes. In the alternative refrigeration/energy system category, subjects include membrane module for dehumidification refrigeration, desiccant-assisted low-temperature drying, regenerative evaporative cooler and ejector-assisted multi-stage evaporation. In the system control category, subjects include multi-refrigeration system control, emergency cooling of data center and variable-speed compressor control. (4) In building mechanical system research fields, fifteenth studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, renewable energies, etc. Proposed designs, performance tests using numerical methods and experiments provide useful information and key data which could be help for improving the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the analyses of indoor thermal environments controlled by portable cooler, the effects of outdoor wind pressure in airflow at high-rise buildings, window air tightness related to the filling piece shapes, stack effect in core type's office building and the development of a movable drawer-type light shelf with adjustable depth of the reflector. The subjects of building energy were worked on the energy consumption analysis in office building, the prediction of exit air temperature of horizontal geothermal heat exchanger, LS-SVM based modeling of hot water supply load for district heating system, the energy saving effect of ERV system using night purge control method and the effect of strengthened insulation level to the building heating and cooling load.

Optimization of Characteristic Change due to Differences in the Electrode Mixing Method (전극 혼합 방식의 차이로 인한 특성 변화 최적화)

  • Jeong-Tae Kim;Carlos Tafara Mpupuni;Beom-Hui Lee;Sun-Yul Ryou
    • Journal of the Korean Electrochemical Society
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    • v.26 no.1
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    • pp.1-10
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    • 2023
  • The cathode, which is one of the four major components of a lithium secondary battery, is an important component responsible for the energy density of the battery. The mixing process of active material, conductive material, and polymer binder is very essential in the commonly used wet manufacturing process of the cathode. However, in the case of mixing conditions of the cathode, since there is no systematic method, in most cases, differences in performance occur depending on the manufacturer. Therefore, LiMn2O4 (LMO) cathodes were prepared using a commonly used THINKY mixer and homogenizer to optimize the mixing method in the cathode slurry preparation step, and their characteristics were compared. Each mixing condition was performed at 2000 RPM and 7 min, and to determine only the difference in the mixing method during the manufacture of the cathode other experiment conditions (mixing time, material input order, etc.) were kept constant. Among the manufactured THINKY mixer LMO (TLMO) and homogenizer LMO (HLMO), HLMO has more uniform particle dispersion than TLMO, and thus shows higher adhesive strength. Also, the result of the electrochemical evaluation reveals that HLMO cathode showed improved performance with a more stable life cycle compared to TLMO. The initial discharge capacity retention rate of HLMO at 69 cycles was 88%, which is about 4.4 times higher than that of TLMO, and in the case of rate capability, HLMO exhibited a better capacity retention even at high C-rates of 10, 15, and 20 C and the capacity recovery at 1 C was higher than that of TLMO. It's postulated that the use of a homogenizer improves the characteristics of the slurry containing the active material, the conductive material, and the polymer binder creating an electrically conductive network formed by uniformly dispersing the conductive material suppressing its strong electrostatic properties thus avoiding aggregation. As a result, surface contact between the active material and the conductive material increases, electrons move more smoothly, changes in lattice volume during charging and discharging are more reversible and contact resistance between the active material and the conductive material is suppressed.