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

Abstract

Herein, an approach is reported to prepare porous a carbon/Ge (C/Ge) hybrid. In this hybrid, Ge nanoparticles are closely embedded in a highly conductive and flexible carbon matrix. Such a hybrid features a high surface area (128.0 m(2) g(-1)) and a hierarchical micropore-mesopore structure. When used as an anode material in lithium-ion batteries (LIBs), the as-prepared hybrid [C/Ge (60.37%)] exhibits an improved lithium storage performance with regard to its capacity and rate capability compared to its counterparts. More specifically, it can maintain a specific capacity as high as 906 mAh g(-1) at a high current density of 0.6 A g(-1) after 50 cycles. The excellent lithium storage performance of the C/Ge (60.37%) sample can be attributed to synergetic effects between the carbon matrix and Ge nanoparticles. The method we adopted is simple and effective, and can be extended to fabricate other nanomaterials.

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

“…Porous Ge–carbon hybrid anode with an interconnected carbon buffering network and mesoporous structure, delivered a long cycle life over 2000 cycles with a low capacity fading of 0.006% per cycle . Porous C/Ge hybrid with high surface area of 128.0 m 2 g −1 and hierarchical micropore‐mesopore structure exhibited specific capacity of 906 mAh g −1 at a current density of 0.6 A g −1 after 50 cycles . 3D mesoporous Ge coated with carbon (3D‐Ge/C) prepared by carbothermal reduction showed excellent cyclability, almost 86.8% capacity retention, corresponding to a charge capacity of 1216 mAh g −1 after 1000 cycles at a 2 C rate.…”

Germaniumbasierte Nanomaterialien für wiederaufladbare Batterien

“…Gegenüber der magnesiothermischen Reduktion hat die Wasserstoffreduktion den Vorteil, dass keine Säurekorrosion erforderlich ist, was das Verfahren umweltfreundlicher gestaltet . Ein weiteres vielversprechendes Merkmal der Wasserstoffreduktion ist, dass in Ge/C‐Hybriden verschiedene Arten von Hohlräumen, wie mesoporöses, hohles Ge und poröses amorphes Ge, erhalten werden können.…”

“…Zyklus bei einer Stromdichte von 160 mA g −1 ergaben. Mesoporöse hohle Germanium@Kohlenstoff‐Nanostrukturen, hierarchische Mikroporen/Mesoporen‐Kohlenstoff/Ge(C/Ge)‐Hybride und hohler Kohlenstoff mit verkapseltem Germanium (Ge@HCS; Abbildung ) zeigten alle ähnlich hohe reversible Kapazitäten, z. B.…”

Capillary-Induced Ge Uniformly Distributed in N-Doped Carbon Nanotubes with Enhanced Li-Storage Performance

“…The lithium storage mechanism of the Ge@N‐CNTs was investigated by using cyclic voltammetry (CV), as shown in Figure b. There is a small reduction peak located at 0.16 V in the first cycle, which could be attributed to the formation of Li–Ge phase . This peak disappears, however, after the first cycle, and new peak appears at 0.36 V, suggesting the phase transition from lithiated Li x Ge to amorphous Ge .…”

“…There is a small reduction peak located at 0.16 V in the first cycle, which could be attributed to the formation www.advancedsciencenews.com small 2017, 13, 1700920 of Li-Ge phase. [43][44][45][46] This peak disappears, however, after the first cycle, and new peak appears at 0.36 V, suggesting the phase transition from lithiated Li x Ge to amorphous Ge. [47] In the case of Ge/N-CNTs, there is an obvious reduction peak centered at 1.3 V in the first cycle, which could be assigned to the formation of a solid electrolyte interphase (SEI) film between the Ge nanoparticles and the electrolyte ( Figure S5, Supporting Information).…”