caa a22 4500 528785877 20190713030955.0 cr unu---uuuuu 180924s2015 xx s 000 0 eng 10.3929/ethz-b-000104246 doi 10.1038/ncomms9169 doi (ETHRESEARCH)oai:www.research-collection.ethz.ch:20.500.11850/104246 Combined operando X-ray diffraction-electrochemical impedance spectroscopy detecting solid solution reactions of LiFePO4 in batteries [Elektronische Daten] [Michael Hess, Tsuyoshi Sasaki, Claire Villevieille, Petr; id_orcid 0000-0001-6993-5021 Novak] Nat Commun Open access ethresearch Lithium-ion batteries are widely used for portable applications today; however, often suffer from limited recharge rates. One reason for such limitation can be a reduced active surface area during phase separation. Here we report a technique combining high-resolution operando synchrotron X-ray diffraction coupled with electrochemical impedance spectroscopy to directly track non-equilibrium intermediate phases in lithium-ion battery materials. LiFePO4, for example, is known to undergo phase separation when cycled under low-current-density conditions. However, operando X-ray diffraction under ultra-high-rate alternating current and direct current excitation reveal a continuous but current-dependent, solid solution reaction between LiFePO4 and FePO4 which is consistent with previous experiments and calculations. In addition, the formation of a preferred phase with a composition similar to the eutectoid composition, Li0.625FePO4, is evident. Even at a low rate of 0.1C, ∼20% of the X-ray diffractogram can be attributed to non-equilibrium phases, which changes our understanding of the intercalation dynamics in LiFePO4. Creative Commons Attribution 4.0 International http://creativecommons.org/licenses/by/4.0 ethresearch Hess Michael joint author Sasaki Tsuyoshi joint author Villevieille Claire joint author Novak Petr; id_orcid 0000-0001-6993-5021 joint author Nature Communications London : Nature Publishing Group 6, p. 8169 2041-1723 http://hdl.handle.net/20.500.11850/104246 text/html WWW-Backlink auf das Repository (Open access) 1 Journal Article ethresearch ETHRESEARCH 856 40 http://hdl.handle.net/20.500.11850/104246 text/html WWW-Backlink auf das Repository (Open access) ETHRESEARCH 700 1- Hess Michael joint author ETHRESEARCH 700 1- Sasaki Tsuyoshi joint author ETHRESEARCH 700 1- Villevieille Claire joint author ETHRESEARCH 700 1- Novak Petr; id_orcid 0000-0001-6993-5021 joint author ETHRESEARCH 773 0- Nature Communications London : Nature Publishing Group 6, p. 8169 2041-1723 BK010053 XK010053 XK010000 ETHRESEARCH ETHRESEARCH ETHRESEARCH Journal Article Open access