Sodium‐ion batteries are emerging as promising candidates for grid energy storage because of the abundant sodium resources and low cost. However, the identification and development of suitable anode materials is far from being satisfactory. Here, it is demonstrated that the Ti₂Nb₂O₉ nanosheets with tunnel structure can be used as suitable anode materials for sodium‐ion batteries. Ti₂Nb₂O₉ nanosheets are synthesized by liquid exfoliation combined with topotactic dehydration, delivering a high reversible capacity of 250 mAh g⁻¹ at 50 mA g⁻¹ at a suitable average voltage of ≈0.7 V. It is found that a low energy diffusion barrier, enlarged interlayer spacing, and exceptional nanoporosity together give rise to high rate performance characterized by pseudocapacitive behavior. The observed high reversible capacity, excellent rate capability, and good cyclability of Ti₂Nb₂O₉ nanosheets make this material competitive when compared to other sodium insertion anode materials.

中文翻译：

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具有伪电容特性的超薄Ti2Nb2O9纳米片可作为钠离子电池的高级阳极

钠离子电池由于其丰富的钠资源和低成本而正在成为电网储能的有希望的候选者。然而，合适的阳极材料的鉴定和开发远远不能令人满意。在此证明，具有隧道结构的Ti ₂ Nb ₂ O ₉纳米片可用作钠离子电池的合适负极材料。Ti ₂ Nb ₂ O ₉纳米片是通过液体剥离与全程脱水相结合合成的，在50 mA g ^-1时可产生250 mAh g ^-1的高可逆容量在≈0.7V的合适平均电压下，发现低能量扩散势垒，扩大的层间间距和出色的纳米孔隙度共同带来了以伪电容特性为特征的高倍率性能。与其他钠插入阳极材料相比，观察到的Ti ₂ Nb ₂ O ₉纳米片材的高可逆容量，出色的倍率性能和良好的循环性使该材料具有竞争力。