Revealing the Intercalation Mechanisms of Lithium, Sodium, and Potassium in Hard Carbon,Advanced Energy Materials

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Revealing the Intercalation Mechanisms of Lithium, Sodium, and Potassium in Hard Carbon
Advanced Energy Materials ( IF 24.4 ) Pub Date : 2020-04-15 , DOI: 10.1002/aenm.202000283
Stevanus Alvin ₁ , Handi Setiadi Cahyadi ₁ , Jieun Hwang ₂ , Wonyoung Chang ₃ , Sang Kyu Kwak ₄ , Jaehoon Kim _{1,

2,

5}

Affiliation

Hard carbon is the most promising anode material for sodium‐ion batteries and potassium‐ion batteries owing to its high stability, widespread availability, low‐cost, and excellent performance. Understanding the carrier‐ion storage mechanism is a prerequisite for developing high‐performance electrode materials; however, the underlying ion storage mechanism in hard carbon has been a topic of debate because of its complex structure. Herein, it is demonstrated that the Li⁺‐, Na⁺‐, and K⁺‐ion storage mechanisms in hard carbon are based on the adsorption of ions on the surface of active sites (e.g., defects, edges, and residual heteroatoms) in the sloping voltage region, followed by intercalation into the graphitic layers in the low‐voltage plateau region. At a low current density of 3 mA g^–1, the graphitic layers of hard carbon are unlocked to permit Li⁺‐ion intercalation, resulting in a plateau region in the lithium‐ion batteries. To gain insights into the ion storage mechanism, experimental observations including various ex situ techniques, a constant‐current constant‐voltage method, and diffusivity measurements are correlated with the theoretical estimation of changes in carbon structures and insertion voltages during ion insertion obtained using the density functional theory.

中文翻译：

揭示硬碳中锂，钠和钾的嵌入机理

硬碳由于其高稳定性，广泛的可用性，低成本和出色的性能，是钠离子电池和钾离子电池最有希望的负极材料。了解载流子存储机制是开发高性能电极材料的先决条件。然而，由于其复杂的结构，硬碳中潜在的离子存储机制一直是一个争论的话题。在此证明了Li ⁺ -，Na ⁺ -和K ⁺硬碳中的离子存储机制是基于离子在倾斜电压区域中的活性位点（例如，缺陷，边缘和残留的杂原子）表面上的吸附，然后嵌入低压高原的石墨层中地区。在3 mA g ^–1的低电流密度下，硬碳的石墨层被解锁以允许Li ⁺离子嵌入，导致锂离子电池达到平稳区域。为了深入了解离子存储机理，将包括各种异位技术，恒流恒压方法和扩散率测量在内的实验观察与使用密度获得的离子插入过程中碳结构和插入电压变化的理论估计相关联功能理论。

更新日期：2020-04-15

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