Aniline Tetramer‐Graphene Oxide Composites for High Performance Supercapacitors

Polyaniline (PANI), a promising conducting polymer for supercapacitor, exhibits high specific capacitance and good rate capability. However, it suffers from low cycling stability due to the breakage or scission of polymer chains and loss of contact caused by the volume change during the charge–discharge, as well as the irreversible oxidation and reduction. Here, a strategy for using aniline tetramers loaded on graphene oxide (AT‐GO) is developed to prevent chain breaking and increase the tolerance of volume change. The potential window is also controlled to reduce the irreversible reactions. In a three electrode test, AT‐GO exhibits a good cycling stability with specific capacitance remaining more than 93 to 96% after 2000 cycles. In a two electrode test, the specific capacitance remains 97.7% of its initial specific capacitance after 2000 cycles by suppressing the side reactions. AT‐GO also shows a high specific capacitance of more than 769 F g^?1 at 1 A g^?1 and it remains 581 F g^?1 at 60 A g^?1, suggesting a good rate capability. These results suggest that AT‐GO is a promising electrode material for practical applications.     

Achieving High Rate Performance in Layered Hydroxide Supercapacitor Electrodes

Layered hydroxides (LHs) are promising supercapacitor electrode materials with high specific capacitances. However, they generally exhibit poor energy storage ability at high current densities due to their insulating nature. Nickel‐cobalt‐aluminum LHs are synthesized and chemically treated to form LHs with enhanced conductivity that results in greatly enhanced rate performances. The key role of chemical treatment is to enable the partial conversion of Co²⁺ to a more conductive Co³⁺ state that stimulates charge transfers. Simultaneously, the defects on the LHs caused by the selective etching of Al promoted the electrolyte diffusion within LHs. As a result, the LHs show a high specific capacitance of 738 F g^?1 at 30 A g^?1, which is 57.2% of 1289 F g^?1 at 1 A g^?1. The strategy provides a facile and effective method to achieve high performance LHs for supercapacitor electrode materials.     

All‐Solid‐State,Foldable, and Rechargeable Zn‐Air Batteries Based on Manganese Oxide Grown on Graphene‐Coated Carbon Cloth Air Cathode

Pliable, safe, and inexpensive energy storage devices are in demand to power modern flexible electronics. In this work, a foldable battery based on a solid‐state and rechargeable Zn‐air battery is introduced. The air cathode is prepared by coating graphene flakes on pretreated carbon cloth to form a dense, interconnected, and conducting carbon network. Manganese oxide hierarchical nanostructures are subsequently grown on the large surface area carbon network, leading to high loading of active catalyst per unit volume while maintaining the mechanical and electrical integrity of the air cathode. Solid‐state and rechargeable Zn‐air battery with such air cathode exhibits similar polarization curve and resistance at its flat and folded states. The folded battery is able to deliver a power density as high as ≈32 mW cm^?2 and good cycling stability of up to 110 cycles. In addition, the flat battery shows similar discharge/charge curve and stable cycling performance after 100 times of repeated folding and unfolding, indicating its high mechanical robustness.     

Flexible and Highly Scalable V2O5‐rGO Electrodes in an Organic Electrolyte for Supercapacitor Devices

Vanadium pentoxide–reduced graphene oxide (rGO) free‐standing electrodes are used as electrodes for supercapacitor applications, eliminating the need for current collectors or additives and reducing resistance (sheet resistance 29.1 Ω □^?1). The effective exfoliation of rGO allows improved electrolyte ions interaction, achieving high areal capacitance (511.7 mF cm^?2) coupled with high mass loadings. A fabricated asymmetric flexible device based on rGO/V₂O₅‐rGO (VGO) consists of approximately 20 mg of active mass and still delivers a low equivalent series resistance (ESR) of 3.36 Ω with excellent cycling stability. A prototype unit of the assembled device with organic electrolyte is shown to light up eight commercial light‐emitting diode bulbs.