Atomic Sulfur Covalently Engineered Interlayers of Ti3C2 MXene for Ultra-Fast Sodium-Ion Storage by Enhanced Pseudocapacitance
Atomic Sulfur Covalently Engineered Interlayers of Ti3C2 MXene for Ultra-Fast Sodium-Ion Storage by Enhanced Pseudocapacitance
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原子硫共价工程 Ti3C2 MXene 中间层通过增强赝电容实现超快速钠离子存储
DOI：
10.1002/adfm.201808107
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发表时间：
2019-03-07
影响因子：
19
通讯作者：
Tao, Xinyong
中科院分区：
文献类型：
--
作者：
Luo, Jianmin;Zheng, Jianhui;Tao, Xinyong
2D MXenes由于其高导电性和大的氧化还原活性表面积而在电化学储能领域得到了广泛的应用。然而，由具有小层间距的多层 MXene 制成的电极表现出缓慢的动力学和低钠离子存储容量。在此，展示了 Ti3C2 MXene 具有扩展和设计的层间距，可实现出色的存储能力。经过十六烷基三甲基溴化铵预处理后，S原子成功嵌入Ti3C2层间，通过Ti-S键合形成理想的层间扩展结构，而原始Ti3C2几乎无法嵌入。当退火温度为450℃时，S原子插层Ti3C2（CT-S@Ti3C2-450）电极在0.1 A g（-1）下提供了550 mAh g（-1）的改进的Na离子容量（在15 A g（-1）下约为120 mAh g（-1），这是基于MXene的最佳Na+存储速率性能）远），并且通过增强的赝电容在 10 A g(-1) 下超过 5000 次循环具有出色的循环稳定性。理论计算和动力学分析也验证了增强的钠离子存储能力。将CT-S@Ti3C2-450阳极与商用交流阴极耦合，组装的Na+电容器在高功率密度（8240 W kg(-1)）下提供高能量密度（263.2 Wh kg(-1)）和出色的循环性能。
2D MXenes have been widely applied in the field of electrochemical energy storage owning to their high electrical conductivity and large redox-active surface area. However, electrodes made from multilayered MXene with small interlayer spacing exhibit sluggish kinetics with low capacity for sodium-ion storage. Herein, Ti3C2 MXene with expanded and engineered interlayer spacing for excellent storage capability is demonstrated. After cetyltrimethylammonium bromide pretreatment, S atoms are successfully intercalated into the interlayer of Ti3C2 to form a desirable interlayer-expanded structure via Ti-S bonding, while pristine Ti3C2 is hardly to be intercalated. When the annealing temperature is 450 degrees C, the S atoms intercalated Ti3C2 (CT-S@Ti3C2-450) electrode delivers the improved Na-ion capacity of 550 mAh g(-1) at 0.1 A g(-1) (approximate to 120 mAh g(-1) at 15 A g(-1), the best MXene-based Na+-storage rate performance reported so far), and excellent cycling stability over 5000 cycles at 10 A g(-1) by enhanced pseudocapacitance. The enhanced sodium-ion storage capability has also been verified by theoretical calculations and kinetic analysis. Coupling the CT-S@Ti3C2-450 anode with commercial AC cathode, the assembled Na+ capacitor delivers high energy density (263.2 Wh kg(-1)) under high power density (8240 W kg(-1)), and outstanding cycling performance.