With the advantages including wide ESW, superior conductivity, low viscosity and low cost, NaClO4-based WIS electrolyte can be considered as a promising candidate for high-voltage and high-rate aqueous carbon based SCs with good safety.
Portable and wearable sensors have attracted considerable attention in the healthcare field because they can be worn or implanted into a human body to monitor environmental information. However, sensors cannot work independently and require power. Flexible in-plane micro-supercapacitor (MSC) is a suitable power device that can be integrated with sensors on a single chip. Meanwhile, paper is an ideal flexible substrate because it is cheap and disposable and has a porous and rough surface that enhances interface adhesion with electronic devices. In this study, a new strategy to integrate MSCs, which have excellent electrochemical and mechanical performances, with sensors on a single piece of paper is proposed. The integration is achieved by printing Ni circuit on paper without using a precoating underlay. Ink diffusion is also addressed to some degree. Meanwhile, a UV sensor is integrated on a single paper, and the as-integrated device shows good sensing and self-powering capabilities. MSCs can also be integrated with a gas sensor on one-piece paper and can be charged by connecting it to a solar cell. Thus, it is potentially feasible that a flexible paper can be used for integrating MSCs with solar cell and various sensors to generate, store, and use energy.
Pseudocapacitance-induced electrochemical actuators (EC-actuators) have attracted great attention in robots and artificial intelligence technologies.Despite major efforts to design such EC-actuators, a molecular-level understanding of the deformation mechanism is still lacking. Here, a reversible deformation of a freestanding MnO 2 /Ni bilayer film is demonstrated and in situ electrochemical atomic force microscopy, in situ Raman spectroscopy, and density functional theory simulation are used to study the origin of the deformation. The results show that the electrochemical actuation of the MnO 2 /Ni film is highly related with the redox pseudocapacitive behavior of MnO 2 layer. Valence state variation of Mn element, shortening and lengthening of MnO bond, and insertion and extraction of Na + ions, which all result from the redox pseudocapacitance of MnO 2 during charging and discharging, eventually lead to the reversible contraction and expansion of MnO 2 morphology. Such action counters with the nonactive Ni layer, finally inducing the reversible deformation of the MnO 2 /Ni bilayer film. It is believed that the study can provide useful guidance to design better EC-actuators in the future.hope our study could provide useful guidance to design better EC-actuators in the future.
Aqueous zinc-ion batteries (ZIBs) are promising low-cost and high-safety energy storage devices. However, their capacity decay especially at the initial cyclic stage is a serious issue. Herein, we reveal that the dissolved oxygen in aqueous electrolyte has significant impact on the electrochemistry of Zn anode and ZIBs. After removing oxygen, the symmetrical set-up of Zn/Zn is capable of reversible plating/stripping with a 20-fold lifetime enhancement compared with that in oxygen enrichment condition. Taking aqueous Zn-MnO 2 battery as an example, although the presence of oxygen can contribute an extra capacity over 20% at the initial cycles due to the electrocatalytic activity of MnO 2 with oxygen, the corrosion of Zn anode can be eliminated in the oxygen-free circumstance and thus offering a better reversible energy storage system. The impact of the dissolved oxygen on the cycling stability also exists in other ZIBs using vanadiumbased compounds, Birnessite and Prussian blue analog cathodes.
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