Hard carbons with a disordered graphitic structure show promise as anode materials in next generation Na-ion batteries with stable and high sodiation/desodiation capacities. Since the mechanism of adsorption is not stoichiometric, as opposed to the case of Li-intercalation into graphite (LiC₆), the search for an upper limit for the reversible capacity is an important task. We herein present a highly nanoporous nitrogen doped carbon obtained from ionothermal carbonization of a Zn-imidazolium framework that shows a stable cycling capacity of 496 mAh g^-1 at 30 mA g^-1 and 280 mAh g^-1 at 5 A g^-1 thus demonstrating exceptionally high capacity and outstanding rate performance. Although the reversible capacity was obtained only after extensive SEI formation, our results reveal the potential for much higher reversible capacities than usually observed today using carbons with a tailored porosity in Na-ion batteries. The electrochemical behavior is explained by improved utilization through a nanoscopic transport pore system and large graphitic interlayer distances. Initial SEI formation is herein used to passivate the carbon surface and obtain an ion-sieving coating. The ion sieving can allow for stable cycling at high capacity without further SEI formation because of a formed physical barrier between solvent molecules and metallic sodium.

具有无序石墨结构的硬质碳有望在下一代Na-离子电池中用作阳极材料，具有稳定且高的除氧化/脱硫能力。与锂嵌入石墨（LiC ₆）的情况相反，由于吸附机理不是化学计量的，因此寻找可逆容量的上限是重要的任务。我们在本文中提出了一种从锌-咪唑骨架的离子热碳化获得的高度纳米多孔氮掺杂碳，其在30 mA g ^-1下显示出496 mAh g ^-1的稳定循环容量，在5 A g ^-1下显示出280 mAh g ^-1的稳定循环容量。因此证明了超高的容量和出色的速率性能。尽管可逆容量仅在大量SEI形成后才获得，但我们的结果表明，与如今在Na离子电池中使用具有特定孔隙率的碳时所观察到的可逆容量相比，如今可逆容量要高得多。通过纳米传输孔系统和大石墨层间距离的改进利用来解释电化学行为。最初的SEI形成在本文中用于钝化碳表面并获得离子筛分涂层。由于在溶剂分子和金属钠之间形成了物理屏障，因此离子筛可以实现高容量的稳定循环而无需进一步形成SEI。