Promoting Ge Alloying Reaction via Heterostructure Engineering for High Efficient and Ultra-Stable Sodium-Ion Storage.
Promoting Ge Alloying Reaction via Heterostructure Engineering for High Efficient and Ultra-Stable Sodium-Ion Storage.
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DOI：
10.1002/advs.202002358
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发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
Chen Z
中科院分区：
文献类型：
--
作者：
Shang C;Hu L;Luo D;Kempa K;Zhang Y;Zhou G;Wang X;Chen Z
锗（Ge）基材料由于其高的理论比容量而被认为是钠离子电池的潜在阳极材料。然而，Ge基材料的导电性和Na+扩散性差，导致离子/电子传输延迟和钠存储效率不足，导致反应动力学缓慢。为了本质上最大化Ge的钠存储能力，开发了氮掺杂的碳涂覆的Cu 3Ge/Ge异质结构材料（Cu 3Ge/Ge@ N-C）以增强钠存储。Cu 3Ge/Ge@ N-C的豆荚状结构暴露了许多活性表面以缩短离子传输路径，而碳壳的均匀封装改善了电子传输，从而增强了反应动力学。理论计算表明，Cu 3Ge/Ge异质结构可以提供良好的电子传导，降低Na+扩散势垒，进一步促进Ge合金化反应，提高其贮钠能力，接近理论值。此外，氮掺杂碳在Cu 3Ge/Ge异质结构材料上的均匀封装有效地抑制了其体积膨胀并防止其分解，进一步确保了其在循环时的结构完整性。由于这些独特的优势，所制备的Cu 3Ge/Ge@ N-C电极表现出令人钦佩的放电容量，出色的倍率性能和延长的循环寿命（4.0 A g− 1下4000次循环后为178 mAh g− 1）。氮掺杂的碳包覆的Cu 3Ge/Ge异质结构被开发为用于快速和持久的钠存储的阳极材料。Cu 3Ge/Ge异质结构有效地促进了复合材料中Na+的扩散和电子传导，从而提高了Ge的储钠能力，加速了其氧化还原反应动力学。由于其结构上的优越性，可实现显著的过流能力、优异的倍率性能和增强的循环稳定性。
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). Nitrogen doped carbon‐coated Cu3Ge/Ge heterostructure is developed as anode material for fast and longevous sodium storage. Cu3Ge/Ge heterostructure efficiently promotes the Na+ diffusion and electron conduction in the composite, which enhances the sodium storage capability of Ge and accelerates its redox reaction kinetics. Attributed to the structural superiorities, a remarkable discharge capacity, superb rate capability and enhanced cyclic stability can be realized.
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