Achieving Ultrafast and Stable Na-Ion Storage in FeSe2 Nanorods/Graphene Anodes by Controlling the Surface Oxide
Achieving Ultrafast and Stable Na-Ion Storage in FeSe2 Nanorods/Graphene Anodes by Controlling the Surface Oxide
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通过控制表面氧化物在 FeSe2 纳米棒/石墨烯阳极中实现超快且稳定的钠离子存储
DOI：
10.1021/acsami.8b06318
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发表时间：
2018-07-04
影响因子：
9.5
通讯作者：
Song, Huaihe
中科院分区：
文献类型：
--
作者：
Li, Dan;Zhou, Jisheng;Song, Huaihe
设计用于钠离子存储的具有上级速率和循环性能的过渡金属硒化物（TMS）仍然是巨大的挑战。为了实现这一任务，表面氧化物对钠离子存储行为的FeSe 2的影响进行了研究，通过设计FeSe，具有不同的氧化物含量。发现表面氧化物对FeSe 2的活性有抑制作用。与具有较低氧化物含量的大尺寸FeSe 2相比，具有较高表面氧化物含量的石墨烯上的小尺寸FeSe表现出明显较差的性能。通过控制氧化物含量，制备的FeSe 2纳米棒/石墨烯在0.1 A/g下具有459 mAh/g的高容量和优异的上级倍率性能。当电流密度从0.1 A/g增加到5 A/g时，容量仅下降10%。即使在25 A/g（类似于50 C）下，它也能提供227 mAh/g的容量，800次循环后几乎没有衰减。探讨了表面氧化物的影响机理。该氧化物可以转化为具有高机械强度和低导电性的钠化壳，其产生相变电阻以抑制FeSe 2核的钠化，阻止Na离子和电子在随后的钠化过程中的转移。了解表面氧化物对钠离子存储的影响将有助于设计TMS和其他活性材料。
Designing transitional metal selenides (TMSes) with superior rate and cyclic performance for sodium-ion storage remains great challenges. To achieve this task, the influence of surface oxides on Na-ion storage behavior of FeSe2 is investigated by designing FeSe, with varying oxide content. It is found that surface oxide has an inhibitory effect on the activity of FeSe2. Small-sized FeSe, on graphene with higher surface oxide content exhibits obviously inferior performance compared to large-sized FeSe2 with lower oxide content. By controlling oxide content, the prepared FeSe2 nanorods/graphene exhibits a high capacity of 459 mAh/g at 0.1 A/g and superior rate performance. Only 10% capacity decrease occurs with the increase in current density from 0.1 to 5 A/g. Even at 25 A/g (similar to 50 C), it delivers a capacity of 227 mAh/g with almost no decay after 800 cycles. The influence mechanism of surface oxide is investigated. The oxide can be converted to a sodiated shell with high mechanical strength and poor conductivity, which generates phase-transition resistance to suppress the sodiation of FeSe2 core, blocks the transfer of Na-ions and electrons in subsequent sodiation processes. Understanding the effect of surface oxide on Na-ion storage will be helpful in designing TMSes and other active materials.