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Operation of a 3D Li-ion m -battery

Thin Film Electrolytes for Energy Devices Jane P. Chang, University of California, Los Angeles, DMR 0932761. Outcome : Researchers at UCLA have synthesized ultra-thin ionic conductive films as solid state electrolytes for miniaturized energy storage devices.

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Operation of a 3D Li-ion m -battery

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  1. Thin Film Electrolytes for Energy DevicesJane P. Chang, University of California, Los Angeles, DMR 0932761 • Outcome: Researchers at UCLA have synthesized ultra-thin ionic conductive films as solid state electrolytes for miniaturized energy storage devices. • Impact: Conformal thin-film electrolytes enable the miniaturization of lithium (Li)-ion batteries based on nanowire (NW) electrodes for on-chip power integration or lowering the operating temperature of solid oxide fuel cells (SOFC). The solid electrolyte coating on an electrode surface can also modify the electrochemical reaction kinetics by suppressing undesired reactions. • Explanation: A number of 3D battery designs have been proposed, which involves a non-planar electrode structure and requires a conformal solid electrolyte grown over the electrode. The ALD LiAlSiO4 over SnO2 NWs was conformal and demonstrated the capability on suppressing the formation of Sn NPs during lithiation process, which impedes the application of SnO2 as the electrode. On the other hand, the ultrathin yttriastablized zirconia (YSZ) reduces resistive losses within the cell, allowing efficient cell performance even at reduced operating temperatures. Operation of a 3D Li-ion m-battery

  2. Ionic Conductivity Elevated by Temperature Jane P. Chang, University of California, Los Angeles, DMR 0932761 • To confirm the measured ionic conductivity was from Li transport, ionic conductivity as a function of temperature was measured on amorphous LiAlSiO4 and LixAlyO (LAO) films with thicknesses of 10 nm. The activation energy of LiAlSiO4 and LAO were found to be 0.89 and 0.46 eV, respectively, in good agreement with values reported in literature for bulk LiAlSiO4 and bulk Li-β-Al2O3, confirming that transport in the ALD films arises from Li+ conduction. LiAlSiO4 possesses a higher activation energy compared to LAO, showing the cation compositions, which affect the bonding environment of each atom in the material, plays an important role in Li transport. Ion conductivity of LiAlSiO4 and LAO films, as a function of temperature in comparison with data reported in literature of single crystal b-LiAlSiO4 (┴c) (-∆-), b-LiAlSiO4(//c) (◊), LiAlSiO4 (-▼-)and Li4.4Al0.4Si0.6O4 (-□-)

  3. LiAlSiO4 coating on SnO2 nanowire batteries Jane P. Chang, University of California, Los Angeles, DMR 0932761 • To assess the performance of ALD LiAlSiO4 as a solid electrolyte in integration with nanowires (NW) based electrodes, SnO2 NWs were chosen as SnO2 is a viable anode material. However, one issue for using SnO2 NW as the negative electrode in Li-ion battery is the formation of metallic Sn nanoparticles (NP) during battery cycling, resulting in short-circuit failure and Sn-catalyzed electrolyte decomposition. In order to prevent the formation of large Sn NPs, faster Li transport is required. LiAlSiO4 was applied over SnO2 NWs and demonstrated the capability to suppress the formation of Sn NPs. Li13Sn5 In-situ HRTEM imaging and corresponding SEAD patterns showing that the formation of Sn NPs during SnO2lithiation (top) was suppressed after a 6nm amorphous LiAlSiO4 was coated on the SnO2 NW (bottom).

  4. Synthesis of Ultrathin Yttria-Stabilized-ZirconiaJane P. Chang, University of California, Los Angeles, DMR 0932761 • Ultrathin yttria stabilized zirconia (Y2O3-ZrO2) was synthesized by radical enhanced atomic layer deposition (REALD), after the charactering the growth rate of each constituent oxide, Y2O3 and ZrO2. The growth rates were found to be 0.47 Å/cycle and 0.62 Å/cycle for Y2O3 and ZrO2, respectively. The cationic ratio of deposited YSZ film, prepared as a solid solution, was found to be correlated to the number of constituent oxide cycles. REALD YSZ film with 1:9 (Y-O)-(Zr-O) cycle ratio had a composition of 8.3 mol% of Y2O3, within the target stoichiometry of 8-9 mol% YSZ, a composition that has the highest oxygen conductivity. (a) Growth rate of Y2O3 and ZrO2 synthesized by REALD. (b) Atomic composition of ALD YSZ films as a function of (Y-O): (Zr-O) cycle ratios. It demonstrates the controllability of the YSZ composition by adjusting the ALD cycle ratios.

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