Mukherjee Santanu, Turnley Jonathan, Mansfield Elisabeth, Holm Jason, Soares Davi, David Lamuel, Singh Gurpreet
Department of Mechanical and Nuclear Engineering, Kansas State University, Manhattan, KS 66506, USA.
National Institute of Standards and Technology, Boulder, CO 80305, USA.
R Soc Open Sci. 2019 Aug 14;6(8):190437. doi: 10.1098/rsos.190437. eCollection 2019 Aug.
Growing concerns regarding the safety, flammability and hazards posed by Li-ion systems have led to research on alternative rechargeable metal-ion electrochemical storage technologies. Among the most notable of these are Na-ion supercapacitors and batteries, motivated, in part, by the similar electrochemistry of Li and Na ions. However, sodium ion batteries (SIBs) come with their own set of issues, especially the large size of the Na ion, its relatively sluggish kinetics and low energy densities. This makes the development of novel materials and appropriate electrode architecture of absolute significance. Transition metal dichalcogenides (TMDs) have attracted a lot of attention in this regard due to their relative ease of exfoliation, diverse morphologies and architectures with superior electronic properties. Here, we study the electrochemical performance of Mo-based two-dimensional (2D) layered TMDs (e.g. MoS, MoSe and MoTe), exfoliated in a superacid, for battery and supercapacitor applications. The exfoliated TMD flakes were interfaced with reduced graphene oxide (rGO) to be used as composite electrodes. Electron microscopy, elemental mapping and Raman spectra were used to analyse the exfoliated material and confirm the formation of 2D TMD/rGO layer morphology. For supercapacitor applications in aqueous electrolyte, the sulfide-based TMD (MoS) exhibited the best performance, providing an areal capacitance of 60.25 mF cm. For SIB applications, TMD electrodes exhibited significantly higher charge capacities than the neat rGO electrode. The initial desodiation capacities for the composite electrodes are 468.84 mAh g (1687.82 C g), 399.10 mAh g (1436.76 C g) and 387.36 mAh g (1394.49 C g) for MoS, MoSe and MoTe, respectively. Also, the MoS and MoSe composite electrodes provided a coulombic efficiency of near 100 % after a few initial cycles.
人们对锂离子系统的安全性、易燃性和危害日益担忧，这促使人们对替代性可充电金属离子电化学存储技术展开研究。其中最值得注意的是钠离子超级电容器和电池，部分原因是锂离子和钠离子的电化学性质相似。然而，钠离子电池（SIBs）也有其自身的一系列问题，特别是钠离子尺寸较大、动力学相对迟缓以及能量密度较低。这使得新型材料和合适的电极结构的开发具有绝对的重要性。过渡金属二硫属化物（TMDs）由于相对易于剥离、形态多样且具有优异电子性能的结构，在这方面引起了广泛关注。在此，我们研究了在超强酸中剥离的钼基二维（2D）层状TMDs（如MoS、MoSe和MoTe）在电池和超级电容器应用中的电化学性能。剥离的TMD薄片与还原氧化石墨烯（rGO）结合用作复合电极。利用电子显微镜、元素映射和拉曼光谱分析剥离的材料，并确认二维TMD/rGO层形态的形成。对于水性电解质中的超级电容器应用，硫化物基TMD（MoS）表现出最佳性能，提供了60.25 mF cm的面积电容。对于SIB应用，TMD电极表现出比纯rGO电极显著更高的充电容量。MoS、MoSe和MoTe复合电极的初始脱钠容量分别为468.84 mAh g（1687.82 C g）、399.10 mAh g（1436.76 C g）和387.36 mAh g（1394.49 C g）。此外，经过几个初始循环后，MoS和MoSe复合电极的库仑效率接近100%。
