Germanium Nanograin Decoration on Carbon Shell: Boosting Lithium‐Storage Properties of Silicon Nanoparticles

Abstract

A novel heterostructured Si@C@Ge anode is developed via a two‐step sol–gel method. A facile and straightforward Ge decoration significantly boosts the Li‐storage performance of core–shell Si@C nanoparticles on both mechanics and kinetics. The Si@C@Ge anode shows unprecedented electrochemical performance in terms of accessible capacity, cycling stability, and rate capability when compared to those of a core–shell Si@C anode. Based on the experimental results and analysis of the mechanism, it is evident that high‐conductivity Ge nanograins on the surface facilitates the Li diffusivity and electron transport and guarantees high ion accessibility. Moreover, it is the Ge nanograins that serve as buffering cushion to tolerate the mechanic strain distribution on the electrode during lithiation/delithiation processes.

Unique Structural Design and Strategies for Germanium‐Based Anode Materials Toward Enhanced Lithium Storage

“…Therefore, tremendous efforts have been devoted into fabricating nanostructured materials, such as nanoparticles, [17,[37][38][39] nanowires, [13][14][15]40] nanotubes, [16,[41][42][43] nanofibers, [44,45] and nanorods. Furthermore, the bulk-form germanium materials have limited active area, which leads to sluggish lithium-ion diffusion.…”

“…To alleviate or eliminate the adverse influence of these problems, some strategies have been applied to optimize the electrochemical properties, including structural modification, [11,[13][14][15][16][17][18][19][20] modification by surface coating, [21][22][23][24] forming germaniumbased alloys, [25][26][27] and forming binary [28][29][30][31][32][33] or ternary [34][35][36] germanium-based composites. Based on our previous studies and experience, we found that the complete and effectively surface coating on nanostructures with high structural robustness is vital to achieving good electrochemical performance in terms of high specific capacity, superior long-term cyclability, and good rate capability.…”

Engineering Carbon Distribution in Silicon‐Based Anodes at Multiple Scales

“…[15a] What's more, the electrochemical performance such as initial coulombic efficiency [38] and cycling stability [39] can be fur- ther enhanced through decorating metal nanocrystals on the carbon shell. Despite the various carbon coating strategies proposed,r ealizing uniform and conformal carbon coatings is still ac hallenge.…”

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

“…After annealing, the GeO 2 was carbon thermal reduced to Ge while the PVA was carbonized, Ge NPs distributed in the carbon matrix and supported by N‐doped carbon foam was obtained . A novel heterostructured Si@C@Ge anode was developed via a two‐step sol‐gel method as show in Figure . First, Si NPs were encapsulated with a resorcinol‐formaldehyde resin (RF) polymer layer by using a surfactant template sol‐gel coating method.…”