Electrochemical Lithiation of Ge: New Insights by Operando Spectroscopy and Diffraction

Laura Loaiza (1) , Nicolas Louvain (2, 3) , Bernard Fraisse (2) , Athmane Boulaoued (2, 4, 5) , Antonella Iadecola (6, 3) , Patrik Johansson (5, 4) , Lorenzo Stievano (5, 2, 3) , Vincent Seznec (1, 5, 3) , Laure Monconduit (3, 2, 5)

1 LRCS - Laboratoire réactivité et chimie des solides - UMR CNRS 7314
2 ICGM - Institut Charles Gerhardt Montpellier - Institut de Chimie Moléculaire et des Matériaux de Montpellier
3 RS2E - Réseau sur le stockage électrochimique de l'énergie
4 Chalmers University of Technology [Göteborg]
5 ALISTORE-ERI - Advanced Lithium Energy Storage Systems - ALISTORE-ERI
6 SSOLEIL - Synchrotron SOLEIL

The relatively high cost of metallic germanium (Ge) as a lithium-ion battery negative electrode material is more than counterbalanced by its high capacity, high lithium diffusivity, and electronic conductivity. Using a unique and highly complementary set of operando characterization techniques, we propose a complete mechanism for the reversible lithiation of Ge. The electrochemical mechanism is found to be determined by the process of discharge/charge: (i) independent of the charge/discharge rate amorphous a-LiGe is proposed as the first intermediate during the lithiation of c-Ge, followed by Li7Ge3, and (ii) at low potential Li15Ge4 is observed, but only for moderate rates and never at low rates, where indeed an “overlithiated” phase is preferred. The complementarity of the data obtained from XAS, Raman spectroscopies, and XRD, all in operando mode, was crucial in order to understand the complex mechanism based on reversible formation of the various crystalline and amorphous phases.

Domaines: Matériaux

Laura Loaiza, Nicolas Louvain, Bernard Fraisse, Athmane Boulaoued, Antonella Iadecola, et al.. Electrochemical Lithiation of Ge: New Insights by Operando Spectroscopy and Diffraction. Journal of Physical Chemistry C, 2018, 122 (7), pp.3709 - 3718. ⟨10.1021/acs.jpcc.7b11249⟩. ⟨hal-01717911⟩