Pseudocapacitance contribution in boron-doped graphite sheets for anion storage enables high-performance sodium-ion capacitors
Pseudocapacitance contribution in boron-doped graphite sheets for anion storage enables high-performance sodium-ion capacitors
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DOI：
10.1039/c8mh00156a
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发表时间：
2018-05
影响因子：
13.3
通讯作者：
F. Yu;Zaichun Liu;Renwu Zhou;Deming Tan;Hongxia Wang;Faxing Wang
中科院分区：
文献类型：
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作者：
F. Yu;Zaichun Liu;Renwu Zhou;Deming Tan;Hongxia Wang;Faxing Wang
金属离子混合电容器具有高功率密度和高能量密度的优点，是当前储能领域研究的热点之一。为了改善传统金属-离子混合电容器电极材料法拉第反应迟缓的问题，插层伪电容材料被开发为有吸引力的候选材料。然而，以前报道的插层/脱层反应中的假电容都是基于阳离子(Li+、Na+、Zn2+等)的。在这项工作中，我们利用阴离子存储的优势，证明了掺硼石墨片具有很高的伪电容贡献。BG电极可以通过表面控制的假电容反应和扩散受限的插层/脱嵌反应可逆地存储阴离子(Pf6−)。以BG为阴极制备的钠离子混合电容器具有优异的电化学性能。密度泛函理论计算表明，B掺杂可以显著降低Pf6-−在石墨层中的扩散能垒。
Research on metal-ion hybrid capacitors is emerging as one of the hottest topics in energy storage fields because of their combination of high power and energy densities. To improve the sluggish faradaic reaction in traditional electrode materials for metal-ion hybrid capacitors, intercalation pseudocapacitive materials have been developed as attractive candidates. However, all the previously reported pseudocapacitances in intercalation/deintercalation reactions are based on cations (Li+, Na+, Zn2+etc.). In this work, we demonstrated the high pseudocapacitance contribution in boron-doped graphite (BG) sheets by taking advantage of anion storage. The BG electrode can reversibly store anions (PF6−) through both a surface-controlled pseudocapacitive reaction and a diffusion-limited intercalation/deintercalation reaction. The fabricated Na-ion hybrid capacitor with a BG cathode exhibits superior electrochemical performance. Density functional theory (DFT) calculation reveals that B-doping can significantly reduce the PF6− diffusion energy barrier in the graphite layers.