Ti3C2Tx MXene with High Pseudocapacitive Activity and Large Potential Window in a Mild AlCl3 Aqueous Electrolyte,Small Methods

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Ti3C2Tx MXene with High Pseudocapacitive Activity and Large Potential Window in a Mild AlCl3 Aqueous Electrolyte
Small Methods ( IF 10.7 ) Pub Date : 2023-04-13 , DOI: 10.1002/smtd.202201526
Yongqiu Xian ₁ , Bin Wang ₁ , Zifeng Lin ₁

Affiliation

MXenes have been extensively explored as supercapacitor electrodes, especially in acidic aqueous electrolytes, where ultrahigh specific capacitance can be achieved; however, their narrow working potential window (≤ 1.0 V) limits the acquisition of high energy. Neutral and alkaline electrolytes can be used to extend the working potential window but MXenes in these electrolytes are less pseudocapacitive active, which leads to reduced charge storage. In this study, it is shown that Ti₃C₂T_x MXene in a mild AlCl₃ aqueous electrolyte can operate at a wide potential range from 0 to −1.3 V versus Hg/Hg₂SO₄ and retain high pseudocapacitive activity. Thus, a high capacity of up to 85 mAh g⁻¹ is achieved, surpassing its performance in H₂SO₄ electrolyte of 78 mAh g⁻¹. More interestingly, most of the capacity is released at a more negative potential range than that in acidic electrolytes, making it more suitable as a negative electrode material. In situ electrochemical quartz crystal microbalance results suggest that the high capacity originates from the pseudocapacitive intercalation/deintercalation of H⁺ instead of Al³⁺, providing the possibility of coupling MXene anodes with proton redox active cathodes to achieve high-energy and high-power devices.

中文翻译：

Ti3C2TX MXene 在温和的 AlCl3 水电解质中具有高赝电容活性和大电位窗口

MXenes 作为超级电容器电极已被广泛探索，特别是在酸性水性电解质中，可以实现超高比电容；然而，它们狭窄的工作电位窗口（≤ 1.0 V）限制了高能量的获取。中性和碱性电解质可用于扩展工作电位窗口，但这些电解质中的 MXene 赝电容活性较低，这会导致电荷存储减少。在这项研究中，结果表明，温和的 AlCl _{3水性电解质中的 Ti}₃ C ₂ T _x MXene相对于 Hg/Hg ₂ SO ₄可以在 0 至 -1.3 V 的宽电位范围内工作，并保持高赝电容活性。因此，实现了高达85mAh g ^{-1的高容量，超过了其在H}₂ SO ₄电解质中的78mAh g ^-1的性能。更有趣的是，大部分容量是在比酸性电解质更负的电位范围内释放的，这使得它更适合作为负极材料。原位电化学石英晶体微天平结果表明，高容量源于H ⁺而不是Al ³⁺的赝电容嵌入/脱嵌，为MXene阳极与质子氧化还原活性阴极耦合以实现高能和高功率器件提供了可能性。

更新日期：2023-04-13

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