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(De)Lithiation and Strain Mechanism in Crystalline Ge Nanoparticles

Abstract : Germanium is a promising active material for high energy density anodes in Li-ion batteries thanks to its good Li-ion conduction and mechanical properties. However, a deep understanding of the (de)lithiation mechanism of Ge requires advanced characterizations to correlate structural and chemical evolution during charge and discharge. Here we report a combined operando X-ray diffraction (XRD) and ex situ 7Li solid-state NMR investigation performed on crystalline germanium nanoparticles (c-Ge Nps) based anodes during partial and complete cycling at C/10 versus Li metal. High-resolution XRD data, acquired along three successive partial cycles, revealed the formation process of crystalline core–amorphous shell particles and their associated strain behavior, demonstrating the reversibility of the c-Ge lattice strain, unlike what is observed in the crystalline silicon nanoparticles. Moreover, the crystalline and amorphous lithiated phases formed during a complete lithiation cycle are identified. Amorphous Li7Ge3 and Li7Ge2 are formed successively, followed by the appearance of crystalline Li15Ge4 (c-Li15Ge4) at the end of lithiation. These results highlight the enhanced mechanical properties of germanium compared to silicon, which can mitigate pulverization and increase structural stability, in the perspective for developing high-performance anodes.
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Submitted on : Monday, May 30, 2022 - 8:42:29 AM
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Diana Zapata Dominguez, Christopher Berhaut, Anton Buzlukov, Michel Bardet, Praveen Kumar, et al.. (De)Lithiation and Strain Mechanism in Crystalline Ge Nanoparticles. ACS Nano, American Chemical Society, 2022, 16 (6), pp.9819-9829. ⟨10.1021/acsnano.2c03839⟩. ⟨cea-03681043⟩



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