Operando X-ray Scattering and Spectroscopic Analysis of Germanium Nanowire Anodes in Lithium Ion Batteries

Abstract

X-ray diffraction (XRD) and Fourier transform extended X-ray absorption fine structure (EXAFS) analysis of X-ray absorption spectroscopy (XAS) measurements have been employed to determine structural and bonding changes, as a function of the lithium content/state of charge, of germanium nanowires used as the active anode material within lithium ion batteries (LIBs). Our data, collected throughout the course of battery cycling (operando), indicate that lithium incorporation within the nanostructured germanium occurs heterogeneously, preferentially into amorphous regions over crystalline domains. Maintenance of the molecular structural integrity within the germanium nanowire is dependent on the depth of discharge. Discharging to a shallower cutoff voltage preserves partial crystallinity for several cycles.

Understanding the Reactivity of a Thin Li1.5Al0.5Ge1.5(PO4)3 Solid‐State Electrolyte toward Metallic Lithium Anode

“…This is similar to the lithiation process of the Ge reference electrode, which tends to form Li–Ge alloys and results in a significant decrease in peak magnitude. [ 19–21 ] The peak decrease is due either to the breakdown of the crystalline size or loss of crystallinity. This result clearly confirms that the reduction of LAGP is more pronounced at 80 °C than 25 °C, which is consistent with the results of HEXRD.…”

Structural Strategies for Germanium‐Based Anode Materials to Enhance Lithium Storage

“…Mohammad et al reported using a new oligosilylgermane compounds with weak GeH bonds as precursors for the rapid synthesis of Ge NWs in high yields (>80%), via an SLS mechanism, using In NPs as a seeding agent at a temperature range between 180 and 380 °C. Ge NWs also were synthesized using SFLS method, utilizing gold NPs as seeds . Sn seeded Ge NWs were grown onto stainless steel current collectors through a low cost SVG system .…”

“…Silberstein et al studied the phase transformations within Ge NWs throughout the course of LIBs cycling using operando X‐ray techniques. Experiment data indicated that Li incorporation within the nanostructured Ge occurs heterogeneously, preferentially into amorphous regions over crystalline domains.…”

Enhanced Li-storage performances of dually-protected CoGeO3 nanocomposites as anode materials for lithium ion batteries

“…The conversion between crystalline and amorphous Ge was believed to occur by virtue of amorphous Li 9 Ge 4 [49] or Li 15 Ge 4 [53] during Li-cycling. Very recently, amorphous Li-Ge was solidly confirmed with in-situ 7 Li NMR observation [54] and Operando X-ray techniques [55]. Herein, XRD measurements were carried out to identify the phase compositions of CoGCs/C-4 electrode after the 1 st discharge to 0.01 V (Figure 6b [16].…”