Department of Chemistry, Indian Institute of Technology (Banaras Hindu University), Varanasi, Uttar Pradesh, 221005, India.
Department of Physics, Indian Institute of Technology (Indian School of Mines), Dhanbad 826004, India.
Phys Chem Chem Phys. 2022 Dec 21;25(1):555-569. doi: 10.1039/d2cp03847a.
Currently, enhancing the performance of electrochemical supercapacitors is the subject of intense research to fulfill the ever-increasing demand for grid-scale energy storage and delivery solution, thereby utilizing the full potential of renewable energy resources and decreasing our dependence on fossil fuels. Metal sulfides, such as cobalt sulfide (CoS), nickel sulfide (NiS), molybdenum sulfide (MoS), copper sulfide (CuS), and others, have recently emerged as a promising class of active electrode materials, alongside other supercapacitor electrode materials, due to their relatively high specific capacitance values and exceptional reversible redox reaction activities. The synthesis, characterizations, and electrochemical performances of single-phase nanocrystalline β-NiS are presented here and the electrode based on this material shows a specific capacitance of 1578 F g at 1 A g from the galvanostatic discharge profile, whereas a capacitance of 1611 F g at 1 mV s was obtained through the CV curve in 2 M KOH aqueous electrolyte. Additionally, the electrode also performs well in neutral 0.5 M NaSO electrolytes resulting in specific capacitance equivalent to 403 F g at 1 mV s scan rate. The high charge storage capacity of the material is due to the superior intercalative (inner) charge storage coupled with the surface (outer) charges stored by the β-NiS electrode and was found to be 72% and 28%, respectively, in aqueous 2 M KOH electrolyte. This intercalative charge storage mechanism is also responsible for its excellent cycling stability. Additionally, we assembled aqueous asymmetric supercapacitors (ASCs) with activated carbon (AC) as the negative electrode and the β-NiS electrode as the positive electrode. The combination of the β-NiS electrode and AC with excellent cycling stability resulted in the highest specific energy equivalent to ∼163 W h kg and a specific power of ∼507 W kg at 1 A g current rate.
目前，提高电化学超级电容器的性能是研究的热点，以满足对电网规模储能和输送解决方案的日益增长的需求，从而充分利用可再生能源的潜力，减少对化石燃料的依赖。金属硫化物，如硫化钴（CoS）、硫化镍（NiS）、硫化钼（MoS）、硫化铜（CuS）等，由于其相对较高的比电容值和出色的可逆氧化还原反应活性，已成为一类很有前途的活性电极材料，与其他超级电容器电极材料一起。本文介绍了单相纳米晶β-NiS 的合成、表征和电化学性能，基于该材料的电极在 1 A g 的恒电流放电曲线下表现出 1578 F g 的比电容，而通过在 2 M KOH 水性电解质中的 CV 曲线获得 1611 F g 的电容。此外，该电极在中性 0.5 M NaSO 电解质中也表现良好，在 1 mV s 的扫描速率下比电容等效于 403 F g。该材料具有高电荷存储容量，是由于β-NiS 电极的插层（内部）电荷存储与表面（外部）电荷存储相结合，在 2 M KOH 水性电解质中分别为 72%和 28%。这种插层电荷存储机制也是其优异循环稳定性的原因。此外，我们组装了以活性炭（AC）为负极和β-NiS 电极为正极的水性非对称超级电容器（ASC）。β-NiS 电极和具有优异循环稳定性的 AC 的组合导致最高的比能量等效于约 163 W h kg，在 1 A g 电流速率下的比功率约为 507 W kg。
