%0 Journal Article
%A Dellen, Christian
%A Gehrke, Hans-Gregor
%A Möller, Sören
%A Tsai, Chih-Long
%A Breuer, Uwe
%A Uhlenbruck, Sven
%A Guillon, Olivier
%A Finsterbusch, Martin
%A Bram, Martin
%T Time-of-flight secondary ion mass spectrometry study of lithium intercalation process in LiCoO$_2$ thin film
%J Journal of power sources
%V 321
%@ 0378-7753
%C New York, NY [u.a.]
%I Elsevier
%M FZJ-2016-02540
%P 241-247
%D 2016
%X A detailed time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of the lithium de-/intercalation in thin films of the insertion cathode material lithium cobalt oxide is presented. The LiCoO2 (LCO) thin films are deposited by radio frequency magnetron sputtering at 600 °C, having a (003) preferred orientation after the deposition. The thin electrode films are cycled with liquid electrolyte against lithium metal, showing 80-86% extractable capacities. After disassembling the cells, the depth resolved elemental distribution in the LCO is investigated by ToF-SIMS and glow discharge optical emission spectroscopy. Both techniques show a stepwise lithium distribution in charged state, leading to a lithium depleted layer close to the surface. In combination with the electrochemical results, the qualitative comparison of the different lithium depth profiles yields a reversible lithium extraction in the depleted area below the stability limit for bulk materials of LCO. For bulk LCO, a phase change normally occurs when the lithium concentration in LixCoO2 is lower than x=0.5. As a possible cause for the inhibition of the phase change, the preferred orientation and thus pinning of the crystal structure of the film by the substrate is proposed.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000377729200027
%R 10.1016/j.jpowsour.2016.04.084
%U https://juser.fz-juelich.de/record/809434