Linking pore-size, local atomic structure and electrochemical properties in hard carbon anodes for sodium-ion batteries

Hard carbons are promising anode materials for sodium-ion batteries. However, explicitly linking electrochemical properties to the underlying structural mechanisms, and ultimately the synthetic route, is challenging due to the disordered, multi-length scale features of both the carbons themselves, and the sodium-insertion products. Here we propose to collect small- and wide-angle (total scattering) data on a series of hard carbons with a range of average pore sizes as a function of Na-insertion to determine which areas of the carbon are suitable for the formation of quasimetallic sodium nanoclusters, giving clues as to whether pore size or local structural/electronic environment limits the cluster size and hence low-voltage capacity.

硬碳（Hard carbons）是极具应用前景的钠离子电池（Sodium-ion Batteries）负极材料。然而，由于碳材料本身及钠嵌入产物均具备无序且多尺度的结构特征，想要将电化学性能与内在结构机制乃至合成路径明确关联，仍存在较大挑战。本研究拟针对一系列平均孔径范围各异的硬碳材料，采集其随钠嵌入程度变化的小角与广角（全散射）数据，以此明确碳材料中哪些区域适宜准金属态钠纳米团簇的形成，进而揭示孔径大小或局部结构/电子环境是否会限制团簇尺寸，最终影响低电压容量。