Electrochemical effect of lithium tungsten oxide modification on LiCoO2 thin film electrode

Tetsutaro Hayashi, Jiro Okada, Eiji Toda, Ryuichi Kuzuo, Yasutaka Matsuda, Naoaki Kuwata, Junichi Kawamura

    Research output: Contribution to journalArticlepeer-review

    18 Citations (Scopus)

    Abstract

    We fabricated a lithium tungsten oxide (LWO)-modified LiCoO2 (LCO) thin film electrode by pulsed laser deposition and investigated the reason for its lower resistance as compared with a bare LCO electrode. X-ray diffraction revealed that the LWO layer has a randomly oriented Li2WO4 structure with tetragonal symmetry. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (EDX) indicated that the LWO modification changes the LCO particle surface, and the electrochemical impedance spectroscopy demonstrated that the LWO modification on LCO decreases the lithium ion transfer resistance at the interface between the positive electrode and the liquid electrolyte and increases the frequency factor at the interface. X-ray photoemission spectroscopy, EDX, and electron energy loss spectroscopy (EELS) indicated the presence of phosphate on the surface of the unmodified LCO electrode after electrochemical tests, but EDX and EELS did not indicate the presence of phosphate in the LWO-modified LCO electrode. The absence of phosphates apparently alleviates the hindrance of Li+ ion diffusion and increases the frequency factor in LCO, resulting in lowered Li+ ion transfer resistance at the interface.

    Original languageEnglish
    Pages (from-to)559-567
    Number of pages9
    JournalJournal of Power Sources
    Volume285
    DOIs
    Publication statusPublished - 2015 Jul 1

    Keywords

    • Lithium-ion battery
    • Low resistance
    • Positive electrode
    • Surface modification

    ASJC Scopus subject areas

    • Renewable Energy, Sustainability and the Environment
    • Energy Engineering and Power Technology
    • Physical and Theoretical Chemistry
    • Electrical and Electronic Engineering

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