Lv Jia-He, Wang Jing-Song, He Bin, Wu Tao, Lu An-Hui, Zhang Wenrui, Xu Juping, Yin Wen, Hao Guang-Ping, Li Wen-Cui
State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian, 116024, P. R. China.
Spallation Neutron Source Science Center, Dongguan, 523803, P. R. China.
Adv Sci (Weinh). 2024 Nov;11(42):e2407538. doi: 10.1002/advs.202407538. Epub 2024 Sep 16.
Amorphous carbon holds great promise as anode material for sodium-ion batteries due to its cost-effectiveness and good performance. However, its sodium storage mechanism, particularly the insertion process and origin of plateau capacity, remains controversial. Here, an extended adsorption/insertion-filling sodium storage mechanism is proposed using petroleum coke-derived amorphous carbon as a multi-microcrystalline model. Combining in situ X-ray diffraction, in situ Raman, theoretical calculations, and neutron scattering, the effective storage form and location of sodium ions in amorphous carbon are revealed. The sodium adsorption at defect sites leads to a high-potential sloping capacity. The sodium insertion process occurs in both the pseudo-graphite phase (d > 0.370 nm) and graphite-like phase (0.345 ≤ d < 0.370 nm) rather than the graphite phase, contributing to low-potential sloping capacity. The sodium filling into accessible closed pores forms quasi-metallic sodium clusters, contributing to plateau capacity. The threshold of the effective interlayer spacing for sodium insertion is extended to 0.345 nm, breaking the consensus of insertion interlayer threshold and enhancing understanding of closed pore filling. The extended adsorption/insertion-filling mechanism explains the sodium storage behavior of amorphous carbon with different microstructures, providing theoretical guidance for the rational design of high-performance amorphous carbon anodes.
非晶碳因其成本效益和良好性能，作为钠离子电池的负极材料具有巨大潜力。然而，其储钠机制，特别是嵌入过程和平原容量的起源，仍存在争议。在此，以石油焦衍生的非晶碳为多微晶模型，提出了一种扩展的吸附/嵌入-填充储钠机制。结合原位X射线衍射、原位拉曼光谱、理论计算和中子散射，揭示了钠离子在非晶碳中的有效存储形式和位置。缺陷位点处的钠吸附导致高电位倾斜容量。钠嵌入过程发生在准石墨相（d > 0.370 nm）和类石墨相（0.345 ≤ d < 0.370 nm），而非石墨相，这导致低电位倾斜容量。钠填充到可及的封闭孔隙中形成准金属钠簇，从而产生平台容量。钠嵌入的有效层间距阈值扩展到0.345 nm，打破了嵌入层间距阈值的共识，增强了对封闭孔隙填充的理解。扩展的吸附/嵌入-填充机制解释了不同微观结构的非晶碳的储钠行为，为高性能非晶碳负极的合理设计提供了理论指导。
