Facile Synthesis of Ge@C Core–Shell Nanocomposites for High‐Performance Lithium Storage in Lithium‐Ion Batteries

Abstract

Herein, we report a facile and "green" synthetic route for the preparation of Ge@C core-shell nanocomposites by using a low-cost Ge precursor. Field-emission scanning electron microscopy and transmission electron microscopy analyses confirmed the core-shell nanoarchitecture of the Ge@C nanocomposites, with particle sizes ranging from 60 to 100 nm. Individual Ge nanocrystals were coated by a continuous carbon layer, which had an average thickness of 2 nm. When applied as an anode materials for lithium-ion batteries, the Ge@C nanocomposites exhibited a high initial discharge capacity of 1670 mAh g(-1) and superior rate capability. In particular, Ge@C nanocomposite electrodes maintained a reversible capacity of 734 mAh g(-1) after repeated cycling at a current density of 800 mA g(-1) over 100 cycles.

Ge Nanoparticles Encapsulated in Nitrogen-Doped Reduced Graphene Oxide as an Advanced Anode Material for Lithium-Ion Batteries

“…1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 the electrolyte to form solid electrolyte interphase (SEI) film, resulting in the capacity loss during the first cycle. 21,57,58 The large peak between 0 and 0.51 V is assigned to the reduction of Ge. From the second cycle onward, three apparent peaks located at 0.01, 0.31, and 0.48 V can be attributed to the formation of Li x Ge alloy.…”

“…[18][19][20][21][22][23][24][25] Nevertheless, the practical application of Ge is hindered by the pulverization problem caused by the large volume changes during Li insertion/extraction processes, thus leading to the loss of electrical conductivity and consequently a rapid capacity decline upon cycling. [26][27][28][29][30][31] Previously studies have demonstrated that decreasing the Ge particle size into the nanometer range could alleviate the stress produced during Li uptake and release processes and suppress the tendency of the nanostructure to fracture.…”

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

“…synthesized two Ge/C hybrids with clustered and non‐clustered nanostructures that were both located inside hollow carbon shells . In 2013, a facile solution‐phase‐reduction method was employed to synthesize Ge@C nanocomposites . The as‐prepared Ge@C hybrid, which was coated with a continuous carbon layer with an average thickness of 2 nm, maintained a reversible capacity of 907 mA h g −1 at 4 A g −1 .…”

Freeze‐Drying‐Assisted Synthesis of Hierarchically Porous Carbon/Germanium Hybrid for High‐Efficiency Lithium‐Ion Batteries

“…reported a facile method to prepare Ge@C core–shell composites. The evaluated electrochemical performance indicated that the composites can deliver a high capacity up to 734 mA h g −1 at 0.8 A g −1 14. Guo et al.…”

“…With a theoretical specific capacity of 1600 mAh g −1 , four times higher than that of conventional graphite anode, germanium (Ge) is an excellent candidate as an anode material for LIBs 10–14. It exhibits not only good lithium conductivity (400 times faster than Si), but also high electrical conductivity (104 times higher than Si).…”