Germanium Quantum Dots Embedded in N‐Doping Graphene Matrix with Sponge‐Like Architecture for Enhanced Performance in Lithium‐Ion Batteries

Abstract

Germanium quantum dots embedded in a nitrogen-doped graphene matrix with a sponge-like architecture (Ge/GN sponge) are prepared through a simple and scalable synthetic method, involving freeze drying to obtain the Ge(OH)4 /graphene oxide (GO) precursor and subsequent heat reduction treatment. Upon application as an anode for the lithium-ion battery (LIB), the Ge/GN sponge exhibits a high discharge capacity compared with previously reported N-doped graphene. The electrode with the as-synthesized Ge/GN sponge can deliver a capacity of 1258 mAh g(-1) even after 50 charge/discharge cycles. This improved electrochemical performance can be attributed to the pore memory effect and highly conductive N-doping GN matrix from the unique sponge-like structure.

Extreme biomimetic approach for developing novel chitin-GeO2 nanocomposites with photoluminescent properties

“…Furthermore, the shift in the infrared spectra from 1,066 cm -1 , which corresponds to the C(3)-OH stretch [57] in chitin, to 1,071 cm -1 in the composite is well visible. Qin et al [58] reported that the formation of Ge-O-C bonds between germanium oxide and graphene oxide can be also indicated by the presence of a band at 1,380 cm -1 . However, in the case of this chitin-based composite, the absorbance at 1,378 cm -1 is assigned to CH bending and asymmetric deformation of CH 3 from chitin.…”

The Research Development of Quantum Dots in Electrochemical Energy Storage

“…Also the hybridized Ge/CNFs nanocomposite exhibited good Li storage performance, including high reversible capacity (1204 mA h g −1 at the current density of 200 mA g −1 ), high capacity retention (87.1% after 100 cycles), and rate property (760 mA h g −1 at 3000 mA g −1 ). Ge QDs embedded in an N‐doping GN matrix with a sponge‐like architecture (Ge/GN sponge) were prepared via freeze‐drying followed by a heat reduction process ( Figure a) . Figure b demonstrated that the Ge/GN sponge showed a good cycling stability, but it was not excellent; furthermore, the cycling stability could be advanced by developing a “double protection” method.…”

Multidimensional Germanium‐Based Materials as Anodes for Lithium‐Ion Batteries

“…Simultaneous carbon coating and the reduction of hollow ellipsoidal GeO 2 precursors facilitated the preparation of mesoporous and hollow ellipsoidal Ge encapsulated by a carbon source (Ge@C) that exhibited better cycling stability and higher rate capability than the solid analogue. In 2014, we also reported examples of embedding Ge NPs into an N‐doped porous carbon matrix (Figure ), such as a mesoporous Ge/N‐doped graphene (Ge/N‐GN sponge) and microporous Ge/N‐doped carbon nanofibers (Ge/N‐CNFs) . Compared with N‐GNs and N‐CNFs, an N‐doped mesoporous carbon matrix (CMK‐3)—a typical mesoporous carbon matrix—also acts as a rigid support and conductive framework, thereby providing good access to the electrolyte for fast charge transfer .…”

“… a) Schematic representation of the formation of a Ge/N‐GN sponge; b) TEM images of the Ge/N‐GN sponge; c) schematic representation of the formation of Ge/N−CNFs . EDA‐Ge‐PVP was obtained by dissolving GeO 2 in water‐ethanediamine (EDA) mixed solvent in the presence of polyvinylpyrrolidone (PVP).…”