Browsing by Author "Lee, Wen Chao"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    AQUEOUS LIQUID SOLUTIONS FOR LI-LIQUID BATTERY
    (Office of the Vice Chancellor for Research, 2012-04-13) Salim, Jason; Cheah, Seong Shen; Lee, Wen Chao; Mahootcheian Asl, Nina; Chen, Rongrong; Kim, Youngsik
    The evolvement of Lithium-ion battery industries has begun to carry the industries to step in a new revolution. Consequently, high demand in high energy density batteries in many electronic and electrical appliances, espe-cially energy storage industries been emerged. This new type of batteries has been in extensive research, such as lithium-water battery. Lithium-water battery is a newly developed battery with lithium as the anode and water as the cathode. Lithium is known as one of the most reac-tive metals in periodic table. Therefore, rigorous reaction will be observed when lithium is reacted with water and hence potentially providing an ex-tremely high energy density. This rigorous reaction can be converted into electrical energy and can be stored in a cell. Lithium-water battery is novel and hence, there is no standardized design. In this presentation, lithium anode is separated from water by liquid electrolyte and a ceramic solid electrolyte. The glass-ceramic solid electro-lyte which has Li1.3Ti1.7Al0.3(PO4)3 composition plays an important role of the design of this lithium–water battery. The main purpose of the solid electro-lyte is to separate water from lithium, avoiding a dangerous exothermic re-action. Also, the presence of the super-ionic conductor ceramic can provide very high lithium ion conductivity. The different sizes of solid electrolytes were used in designing Li-liquid battery cell. The effect of the electrolyte size on the voltage of the cell was studied to optimize the cell design. Then, the aqueous solutions containing different chemicals were tested as the liquid cathodes, and their electro-chemical performance were compared to those of the pure DI water. Further results will be presented in the poster presentation.
  • Thumbnail Image
    Item
    CHEMICAL AND PHASE TRANSFORMATION FROM VANADIUM SULFIDE TO OXIDE VIA A NEW CHEMICAL ROUTE FOR THE SYNTHESIS OF Βʹ-LIXV2O5 AS A HIGH PERFORMANCE CATHODE
    (Office of the Vice Chancellor for Research, 2014-04-11) Lee, Wen Chao; Mahootcheian Asl, Nina; Kim, Youngsik; Zhu, Likun
    The used of rechargeable lithium ion batteries are so widely nowadays on consumer electronics especially portable devices such as cellphones, laptops and etc. The advancement of technology has created batteries with providing high energy density without memory effect and minimum the self-discharge on standby mode. Even with these features, researchers are still trying to improve the batteries with more energy density, low cost, better safety and high durability. The energy density improves with high operation voltage and high capacity. All these features came from one source, material. The resources for current commercial cathode material are decreasing and so new alternative cathode with high performance is needed to replace the commercial cathode in the future. The high temperature vanadium pentoxide phase, βʹ-LixV2O5, was synthesized via a new chemical synthesis involving the evolution of vanadium oxides from the 600°C heat treatment of the pure LiVS2 in air. By employing this method of synthesis, well-crystalized, rod-shaped βʹ-LixV2O5 particles 20 – 30 μm in length and 3 – 6 μm in width were obtained. Moreover, the surface of βʹ-LixV2O5 particles was found to be coated by an amorphous vanadium oxysulfide film (~20 nm in thickness). In contrast to a low temperature vanadium pentoxide phase (LixV2O5), the electrochemical intercalation of lithium into the βʹ-LixV2O5 was fully reversible where 0.0 < x < 2.0, and it delivered a capacity of 310 mAh/g at a current rate of 0.07 C between 1.5 V and 4 V. Good capacity retention of more than 88% was also observed after 50 cycles even at a higher current rate of 2 C.
  • Thumbnail Image
    Item
    Electrochemical Lithium Harvesting from Waste Li-ion Batteries
    (Poster session presented at IUPUI Research Day 2013, Indianapolis, Indiana., 2013-04-05) Wolfe, Byron M., III; Lee, Wen Chao
    This study demonstrates the feasibility of using water and the contents of waste Li-ion batteries for the electrodes in a Li-liquid battery system. Li metal was collected electrochemically from a waste Li-ion battery containing Li-ion source materials from the battery’s anode, cathode, and electrolyte, thereby recycling the Li contained in the waste battery at the room temperature. The harvested Li metal in the battery system was discharged to produce the electricity by using water as the cathode. The discharge voltage of the water showed 2.7 V at 0.1 mA/cm2 versus Li metal harvested from waste Li-ion batteries, compared to 2.8 V versus fresh Li metal at the same current rate. Since the electrodes for this proposed battery system are water and the contents of waste Li-ion batteries, the cost of the battery decreases, which is an attractive strategy for a large size energy storage application. The new design of a battery cell is accompanied in this research. The cell design has two anodes and one cathode which allow it to charge and discharge simultaneously. Thus far, the designs for the cell have been finalized, and will soon be machined so that testing may follow. This drives toward the hopes that an actual battery will be made which can directly harvest the Li metal from a waste Li-ion battery and gain energy immediately. This research will hopefully introduce a new, higher-energy-potential battery while using waste Li-ion batteries which will drastically reduce the cost of Li-ion batteries.
  • Thumbnail Image
    Item
    Geometric Characteristics of Lithium Ion Battery Electrodes with Different Packing Densities
    (Office of the Vice Chancellor for Research, 2015-04-17) Lim, Cheolwoong; Lee, Wen Chao; Bo, Yan; Song, Zhibin; De Andrade, Vincent; De Carlo, Francesco; Kim, Youngsik; Zhu, Likun
    The microstructure of electrodes plays a critical role in determining the performance of lithium ion batteries (LIBs), because the microstructure can affect the transport and electrochemical processes within electrodes (1-3). Increasing the volume fraction of active materials in the electrode will increase the energy density. However, the electrodes’ structural properties could also be changed significantly and the critical physical and electrochemical processes in LIBs will be affected. Therefore, the performance of a LIB can be optimized for a specific operating condition by designing electrode microstructures. For instance, Hellweg suggested a spatially varying porous electrode model to improve lithium ion transport in electrolyte phase at high charge/discharge rates (4). He showed that the power density of the graded porosity electrode was higher than a homogeneous porosity electrode without energy loss. In this study, we investigate the realistic geometric characteristics of electrode microstructures under different packing densities and the effect of packing density on the performance of LIBs. Moreover, a spatially varying porous electrode will be studied to increase the electrode energy density without losing rate capability. To investigate geometric characteristics of porous microstructures, cathode electrodes were fabricated from a 94:3:3 (weight %) mixture of LiCoO2 (average particle radius = 5 μm), PVDF, and super-P carbon black. To change the packing density, initial thickness of the electrodes was set in a range of 40 ~ 80 μm. Then all electrodes were pressed down to 40 μm by using a rolling press machine. A synchrotron X-ray nano-computed tomography instrument (nano-CT) at the Advanced Phothon Source of Argonne National Lab was employed to obtain morphological data of the electrodes, with a spatial resolution of 60 nm. The morphology data sets were quantitatively analyzed to characterize their geometric properties. Fig. 1 shows the porosity (ε), specific surface area (As, μm-1), tortuosity (τ), and pore size distribution of 4 different electrode microstructures. The pore size distribution of the un-pressed electrode (ε =0.56, black color) demonstrates nonuniformly dispersed active material. The highest packing density electrode (ε =0.36, red color) shows the highest tortuosity. The charge/discharge experiments were also conducted for these 4 different electrodes. The geometric properties and cell testing results will be analyzed and reported. Acknowledgments: This work was supported by US National Science Foundation under Grant No. 1335850. Fig. 1 Geometric characteristics (porosity ε, specific surface area As, tortuosity τ, pore size distribution) of xray generated porous electrode microstructure with different packing densities.