一种新型的碳复合钼掺杂的钒氧化物纳米线钠离子电池正极材料

A New Type Carbon Composited Molybdenum Doped Vanadium Oxide Nanowires as A Cathode Material for Sodium Ion Batteries

近年来,由于锂资源逐渐紧缺而导致其成本增加,锂离子电池发展受到限制.作为一个有潜力的替代者,有着相似电化学机制且成本较低的钠离子电池则发展迅速.但由于钠离子与锂离子相较有着更大半径,钠离子在脱嵌过程中,对大多数电极材料的晶体结构破坏严重.因此,开发新型电极材料对钠离子电池的进一步发展尤为重要.其中,层状钒氧化物作为正极材料被广泛研究.在这项工作中,作者基于钒氧化物,引入钼元素并与碳复合,首次设计合成了一种新型的碳复合钼掺杂的钒氧化物纳米线电极材料,并获得了优良的电化学性能.在50 mA·g^(-1)的电流密度下,最高放电比容量达135.9 mAh·g^(-1),在循环75次后仍有82.6 mAh·g^(-1)的可逆容量,容量保持率高达71.8%;在1000 mA·g^(-1)的高电流密度下循环并回到50 mA·g^(-1)后,可逆放电比容量仍能回复至111.5 mAh·g^(-1).研究结果证明,这种具有超大层间距的新型碳复合钼掺杂的钒氧化物纳米线是一种非常有潜力的储钠材料,为钠离子电池的进一步发展提供了一定的理论基础.

In recent years, the development of lithium ion batteries （LIBs） has been limited due to the insufficient lithium resource and increasing cost. As a promising candidate, sodium ion batteries （SIBs） with the similar electrochemical mechanism and lower cost than LIBs are developing rapidly. However, as a result of the larger radius of Na^＋ compared with Li^＋, the crystalline structures of the most electrode materials are damaged severely during the intercalation of Na^＋, which limits the electrochemical properties of SIBs. Thus, developing new types of electrode materials for SIBs is particularly important. Among the cathode materials, the layered vanadium oxides are being widely studied. In this work, for the first time, we designed and synthesized a new type of carbon composited molybdenum doped vanadium oxide nanowires （MVO/C） with the excellent electrochemical performances. The highest ca- pacity reached 135.9 mAh·g^-1 under 50 mA·g^-1. After 75 cycles, there was still 82.6 mAh·g^-1 with 71.8% capacity remaining. When the current density was first increased to 1000 mA·g^-1 and then went back to 50 mA·g^-1, a high reversible capacity of 111.5 mAh·g^-1 was obtained. The results demonstrated that the new type of carbon composited molybdenum doped vanadium oxide nanowires with a ultra-high interlayer spacing is a promising material for sodium storage, providing a theoretical foundation for the further development of SIBs.