Promoting Ge Alloying Reaction via Heterostructure Engineering for High Efficient and Ultra‐Stable Sodium‐Ion Storage

Abstract

Germanium (Ge)-based materials have been considered as potential anode materials for sodium-ion batteries owing to their high theoretical specific capacity. However, the poor conductivity and Na + diffusivity of Ge-based materials result in retardant ion/electron transportation and insufficient sodium storage efficiency, leading to sluggish reaction kinetics. To intrinsically maximize the sodium storage capability of Ge, the nitrogen doped carbon-coated Cu 3 Ge/Ge heterostructure material (Cu 3 Ge/Ge@N-C) is developed for enhanced sodium storage. The pod-like structure of Cu 3 Ge/Ge@N-C exposes numerous active surface to shorten ion transportation pathway while the uniform encapsulation of carbon shell improves the electron transportation, leading to enhanced reaction kinetics. Theoretical calculation reveals that Cu 3 Ge/Ge heterostructure can offer decent electron conduction and lower the Na + diffusion barrier, which further promotes Ge alloying reaction and improves its sodium storage capability close to its theoretical value. In addition, the uniform encapsulation of nitrogen-doped carbon on Cu 3 Ge/Ge heterostructure material efficiently alleviates its volume expansion and prevents its decomposition, further ensuring its structural integrity upon cycling. Attributed to these unique superiorities, the as-prepared Cu 3 Ge/Ge@N-C electrode demonstrates admirable discharge capacity, outstanding rate capability and prolonged cycle lifespan (178 mAh g −1 at 4.0 A g −1 after 4000 cycles). Sodium-ion batteries (SIBs) have attracted great attention as one of the most promising energy storage devices.

Tailoring Ultrafast and High‐Capacity Sodium Storage via Binding‐Energy‐Driven Atomic Scissors

“…The peaks located at 0.63 V in the first cycle can be attributed to the SEI film. [ 59 ] Furthermore, the small peak located at 0.35 V is associated with the alloying reaction to form the Na x Ge alloy. [ 59 ]…”

“…The peaks located at 0.63 V in the first cycle can be attributed to the SEI film. [59] Furthermore, the small peak located at 0.35 V is associated with the alloying reaction to form the Na x Ge alloy. [59] To further investigate the electrochemical reaction mechanism of the GeTiS 3 anode, in situ Raman and XRD analyses were conducted at a current density of 25 mA g −1 within its initial cycle (Figure 4b,c).…”

“…[59] Furthermore, the small peak located at 0.35 V is associated with the alloying reaction to form the Na x Ge alloy. [59] To further investigate the electrochemical reaction mechanism of the GeTiS 3 anode, in situ Raman and XRD analyses were conducted at a current density of 25 mA g −1 within its initial cycle (Figure 4b,c). At stage I, a redshift of the Raman peaks of GeTiS 3 at 59.6, 80.1, and 97.2 cm −1 can be observed (Figure 4b).…”

Encapsulating Sulfides into Tridymite/Carbon Reactors Enables Stable Sodium Ion Conversion/Alloying Anode with High Initial Coulombic Efficiency Over 89%

“…The surging progress of Li‐ion batteries (LIBs) is impeded by aspects related to the overconsumption of Li and other indispensable/rare elements. [ 1–6 ] Alternatively, research interests are turned to more affordable Na‐ion batteries (SIBs), driven by the low cost/good natural abundance of Na (23 600 ppm in the earth), attainable Co‐free battery technology and their good safety ability of being discharged deeply or kept at 0 V. [ 7–9 ] However, the relatively high electron affinity and large ionic radius for Na (≈102 pm, 34% exceeding ≈76 pm of Li + ) endows SIBs with less output capacity, poor charge‐storage reversibility and inferior capacity retention in long‐term cycling. [ 10–13 ] Particularly, their initial Coulombic efficiency (ICE) often stays below 70% due to a great deal of dead Na + insertion in commercial carbonate electrolytes.…”

Boosting Fast Sodium Ion Storage by Synergistic Effect of Heterointerface Engineering and Nitrogen Doping Porous Carbon Nanofibers

“…[4][5][6][7][8][9][10] Nevertheless, SIBs anodes suffer from sluggish dynamics and structure pulverization issues owing to the larger ionic radius of Na + , leading to poor cycling performance and fast capacity degradation during sodiation/desodiation reaction. [11][12][13][14] Thus, it is urgent to develop the anode electrode for SIBs to realize the ideal Na + sodiation/desodiation and alleviate the strain and stress from the volume changes during charging and discharging.A variety of anode materials have been explored in SIBs, including carbonaceous materials, [15][16][17] alloy materials, [18,19] metal oxides/sulfides, etc. [20][21][22] Among all the materials, metal sulfides (MS x , M = Sn, Sb, Fe, etc.)…”