Sulfur-Rich Graphene Nanoboxes with Ultra-High Potassiation Capacity at Fast Charge: Storage Mechanisms and Device Performance
Sulfur-Rich Graphene Nanoboxes with Ultra-High Potassiation Capacity at Fast Charge: Storage Mechanisms and Device Performance
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DOI：
10.1021/acsnano.0c09290
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发表时间：
2021-01-26
期刊：
影响因子：
17.1
通讯作者：
Mitlin, David
中科院分区：
文献类型：
--
作者：
Sun, Yiwei;Wang, Huanlei;Mitlin, David
钾离子存储碳的快速充电和高可逆容量是一个重大挑战。在这里，我们通过一步化学气相沉积合成了富硫石墨烯纳米盒（SGN），以提供卓越的速率和循环性能作为钾离子电池和钾离子电容器（PIC）阳极。SGN电极在0.05 A g（-1）下表现出516 mAh g（-1）的记录可逆容量，在1 A g（-1）下表现出223 mA h g（-1）的记录快速充电容量，以及在1000次循环后具有89%容量保持率的优异稳定性。此外，基于SGN的PIC显示出非常有利的Ragone图表特性：在505 W kg（-1）下为112 Wh kg（-1），在14618 W kg（-1）下为28 Wh kg（-1），6000次循环后容量保持率为92%。X射线光电子能谱分析说明了一个电荷存储序列主要基于可逆的离子结合在碳的结构化学缺陷和可逆形成的K-S-C和K2 S化合物。透射电子显微镜分析表明，由于离子嵌入，石墨烯的可逆膨胀，这是在低电压下的容量的第二来源。这种插层机制显示出即使在循环1000下也是稳定的。恒电流间歇滴定技术分析得出的扩散系数为10（-10）至10（-12）cm（2）s（-1），比不含S的碳高一个数量级。直接电分析/分析比较表明，化学结合的硫增加了可逆离子键合位点的数量，促进了反应控制的扩散控制动力学，并稳定了固体电解质界面。它还表明，初始库仑效率可以显着提高由标准的碳酸盐基电解质切换到醚基的。
It is a major challenge to achieve fast charging and high reversible capacity in potassium ion storing carbons. Here, we synthesized sulfur-rich graphene nanoboxes (SGNs) by one-step chemical vapor deposition to deliver exceptional rate and cyclability performance as potassium ion battery and potassium ion capacitor (PIC) anodes. The SGN electrode exhibits a record reversible capacity of 516 mAh g(-1) at 0.05 A g(-1), record fast charge capacity of 223 mA h g(-1) at 1 A g(-1), and exceptional stability with 89% capacity retention after 1000 cycles. Additionally, the SGN-based PIC displays highly favorable Ragone chart characteristics: 112 Wh kg(-1) at 505 W kg(-1) and 28 Wh kg(-1) at 14618 W kg(-1) with 92% capacity retention after 6000 cycles. X-ray photoelectron spectroscopy analysis illustrates a charge storage sequence based primarily on reversible ion binding at the structural-chemical defects in the carbon and the reversible formation of K-S-C and K2S compounds. Transmission electron microscopy analysis demonstrates reversible dilation of graphene due to ion intercalation, which is a secondary source of capacity at low voltage. This intercalation mechanism is shown to be stable even at cycle 1000. Galvanostatic intermittent titration technique analysis yields diffusion coefficients from 10(-10) to 10(-12) cm(2) s(-1), an order of magnitude higher than S-free carbons. The direct electroanalytic/analytic comparison indicates that chemically bound sulfur increases the number of reversible ion bonding sites, promotes reaction-controlled over diffusion-controlled kinetics, and stabilizes the solid electrolyte interphase. It is also demonstrated that the initial Coulombic efficiency can be significantly improved by switching from a standard carbonate-based electrolyte to an ether-based one.