Exploitation of carbon materials by efficient and environment-friendly methods is of great scientific and technical significance in meeting the demands of energy storage devices. Here, we demonstrate a low-cost, simple and readily scalable approach for the synthesis of hierarchically N-doped porous carbon (NPC) from an eco-unfriendly and fast-growing hydrophyte, i.e., the stem medulla of water hyacinths. During carbonization treatment, the alkaline or alkali earth elements that naturally exist within the stem medulla can induce the formation of pores accompanying a self-activation process analogous to KOH-activation of carbon materials. The optimized NPC shows a specific area as high as 1005 m² g⁻¹ with a hierarchical porous structure, and manifests excellent electrochemical performance as anode materials for both Li-ion batteries (LIBs) and Na-ion batteries (SIBs), in terms of specific capacity, cycling stability, and rate capability, benefitting from the synergistic effects of the hierarchical porous structure and N-doping.

中文翻译：

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由水葫芦绿色高效地制造多层N掺杂多孔碳，用于高性能锂/钠离子电池†

通过高效，环境友好的方法开采碳材料对满足储能设备的需求具有重大的科学技术意义。在这里，我们展示了一种低成本，简单且易于扩展的方法，该方法可从对生态不利且生长迅速的水生植物（即水葫芦的茎髓）合成层次化的N掺杂多孔碳（NPC）。在碳化处理过程中，茎髓中自然存在的碱金属或碱土金属元素会伴随着类似于碳材料的KOH活化的自活化过程而诱发孔的形成。优化的NPC的比表面积高达1005 m ² g ^-1 具有分层的多孔结构，并且在比容量，循环稳定性和倍率性能方面都受益于协同效应，在锂离子电池（LIB）和钠离子电池（SIB）的阳极材料方面均表现出优异的电化学性能多孔结构和氮掺杂的关系。