The greater availability of sodium (Na) over lithium (Li) motivates development of a Na-ion battery that can compete with a Li-ion battery. In these batteries, both electrodes consist of hosts into which Li⁺ or Na⁺ can be inserted reversibly. Graphite has been the anode host for Li-ion batteries, but the Na⁺ ion is too large to be inserted easily between the flat graphene layers of common graphite. We report the synthesis and electrochemical performance of N-doped carbon nanofibers and tubules with an organic-liquid electrolyte and a large fraction of graphitic carbon and larger spacing (0.38–0.44 nm) between carbon sheets; the carbon hollow tubules yield ultrastable (10,000 cycles), high-rate capabilities of Na⁺ intercalation and deintercalation with reversible capacities up to 346 mAh g⁻¹.

与锂（Li）相比，钠（Na）的可用性更高，这推动了可与锂离子电池竞争的钠离子电池的发展。在这些电池中，两个电极均由主体组成，可以将Li ⁺或Na ⁺可逆地插入其中。石墨一直是锂离子电池的阳极主体，但Na ⁺离子太大，无法轻易插入普通石墨的平坦石墨烯层之间。我们报道了具有有机液体电解质和很大一部分石墨碳以及更大的碳板间距（0.38-0.44 nm）的N掺杂碳纳米纤维和小管的合成和电化学性能。碳空心管产生超稳定的（10,000个循环），高速率的Na ⁺可逆容量高达346 mAh g ^-1的嵌入和脱嵌。