{Reference Type}: Journal Article
{Title}: Promoting Ge Alloying Reaction via Heterostructure Engineering for High Efficient and Ultra-Stable Sodium-Ion Storage.
{Author}: Shang C;Hu L;Luo D;Kempa K;Zhang Y;Zhou G;Wang X;Chen Z;
{Journal}: Adv Sci (Weinh)
{Volume}: 7
{Issue}: 22
{Year}: Nov 2020
{Factor}: 17.521
{DOI}: 10.1002/advs.202002358
{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 Cu3Ge/Ge heterostructure material (Cu3Ge/Ge@N-C) is developed for enhanced sodium storage. The pod-like structure of Cu3Ge/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 Cu3Ge/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 Cu3Ge/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 Cu3Ge/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).