Niobium carbide (NbC) is used as anode material for sodium-ion batteries for the first time. Ball-milled NbC delivers an initial charge capacity of 242 mAh g⁻¹ at 0.1 A g⁻¹ and a capacity of 126 mAh g⁻¹ after 1000 cycles at a high current density of 5 A g⁻¹ without carbon coating. Cyclic voltammetry curves demonstrate that the pseudocapacitive Na⁺ storage behavior dominates the electrochemical reaction, which is responsible for the good rate capability. Ex situ X-ray diffraction (XRD), transmission electron microscopy (TEM), and density functional theory (DFT) calculations show that the electrochemical reaction between NbC and Na is attributed to an adsorption mechanism.

中文翻译：

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碳化铌作为一种有前途的赝电容钠离子存储阳极

碳化铌（NbC）首次被用作钠离子电池的负极材料。球磨的 NbC在 0.1 A g ^-1下提供 242 mAh g ^-1的初始充电容量，在5 A g ^-1的高电流密度下在 1000 次循环后提供 126 mAh g ^-1的容量，没有碳涂层。循环伏安曲线表明，赝电容 Na ⁺存储行为主导着电化学反应，这是良好倍率性能的原因。非原位 X 射线衍射 (XRD)、透射电子显微镜 (TEM) 和密度泛函理论 (DFT) 计算表明，NbC 和 Na 之间的电化学反应归因于吸附机制。