NIMSAWARD2025-abstracts

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P1-1148Key Words: Operandomeasurements, Hard X-ray Photoelectron Spectroscopy, LiCoO2•Elucidating electrochemical reactions of electrode materials for lithium-ion batteries under charge/discharge cycles contributes to establishing guidelines for improving battery performance, such as capacity retention, energy density, and safety•Operandohard X-ray photoelectron spectroscopy (HAXPES) measurements enable us to probe the elemental composition and electronic states of a sample under battery operationsA laboratory-based HAXPES apparatus andbias application system was developedElectrochemical potential of LCO in response to the Li content xin LixCoO2was obtained by the Co3+peak position because the B 1s peak due to LBO was used as an internal standardConclusionThe investigation of electrochemical reactions ofLCO-LBO composite electrode under high-voltage operations is currently ongoingWe plan to perform operandoobservations of electrochemical reactions of LCO thin-film electrode deposited on a LLZT and its LCO/LLZT interfaceFuture PlanIntroduction•A laboratory-based operandoHAXPES apparatus equipped with a Cr-Kαsource (5414.9 eV) and bias application system was developedTheme underDiscussionBattery Materials Analysis Group, GREEN Tsukasa IWAMAE-mail：： IWAMA.Tsukasa@nims.go.jpCo3+peak shifted consistently with cell voltage changeThe value of shift corresponds to electrochemical potential change of LCO in response to the change of Li content xin LixCoO2Experimental and static observationOperandoobservationLCO-LBO composite electrodePt layer Nb layerLi layerLLZT (0.5 mm-t)10 mm10 mmPotential profiles in a range 3.0 –4.2 VThe test cell was cycled 10 times without significant capacity lossPt/LCO-LBO/Nb/LLZT/Li test cellCr-KαraysAnalyzerPotentiostatTest cell put onto the sample holderMain peak was broadened/narrowedin response to the oxidation/reduction of Co3+/4+ions after charge/discharge cycleCo 2p3/2and B 1s photoelectron spectra calibrated by LBO peakElectrode potential and position ofCo3+peak as a function of capacityCo 2p3/2and B 1s photoelectronspectra withoutcalibrationOperando Observation of Electrode Reactions of LiCoO2Electrode Constructed on a Solid Electrolyte Sheet Studied by Hard X-ray Photoelectron SpectroscopyCr-Kα(5414.9 eV)Ar-filled glove boxHemisphericalanalyzerBias-application systemPotentiostatCo-axial cablesTerminalsSampleholderTsukasa Iwama、Tsuyoshi Ohnishi, and Takuya Masuda