Search

In this study, a facile pyrolysis process is utilized to convert a mantis shrimp shell into a 3D bicontinuous porous, highly wrinkled, nitrogen-doped, graphene-like ultrathin carbon sheet (3D BWGC). The 3D BWGC achieves a high surface area of 2300 m2 g−1 and a pore volume of up to 1.63 cm3 g−1. The specific capacitance of the 3D BWGC in 0.5 M H2SO4 electrolyte is 370.9 F g−1 at a current density of 1 A g−1 and an operating voltage window of 1.1 V. By introducing Fe2+, the operating voltage window of 3D BWGC symmetric supercapacitors can reach 1.8 V in a neutral electrolyte, and a specific capacitance of 317.2 F g−1 can be obtained at a current density of 0.5 A g−1. Remarkably, the fabricated symmetric supercapacitors using 2 M MgSO4 + 0.05 M FeSO4 electrolyte demonstrated an energy density as high as 17.7 W h kg−1 at a power density of 180 W kg−1. The assembled supercapacitors exhibit good cycling performance, maintaining an initial capacitance of 87.2% over 30 000 cycles. These excellent performances indicate the promising prospects of 3D BWGC in high-performance electrochemical energy storage. [ABSTRACT FROM AUTHOR]

We developed a one-pot strategy to fabricate activated carbons by using water soluble phenol-formaldehyde resin as precursor and Na 2 CO 3 as activating agent. The prepared carbon materials have a typical hierarchical pore texture and a large specific surface area (SSA) of 1357 m 2 g −1 . When used as electrode materials for supercapacitors, the material shows a high specific capacitance of 226 F g −1 at 0.05 A g −1, good rate capability of 62.4% in the range of 0.05–20 A g −1 and outstanding cycling stability (only 2.5% loss in specific capacitance after 5000 cycles). These results suggest a low-cost and environmentally friendly design of electrode materials for high-performance supercapacitors. [ABSTRACT FROM AUTHOR]

The effect of activated carbon (AC) surface functional groups on the cycle performance of lead-carbon batteries was studied from hydrogen evolution and nano-lead electrodeposition on the surface of the AC. AC materials were modified by oxidation methods (hot air or acid treatment) to increase acidic groups and reduction processes (alkaline treatment or heat treatment in N 2 ) to increase alkaline groups. The surface functional groups were characterized by X-ray photoelectron spectroscopy and Boehm titration method. We used cyclic voltammetry and a three-electrode system to prepare nano-lead deposits on the surface of the AC, and studied its influence on hydrogen evolution of AC. The results show that acidic groups are beneficial to lead electrodeposition. In addition, the lead deposits with high activity covering the surface of AC could inhibit hydrogen evolution and the irreversible sulfation in lead-carbon batteries, and then result in longer cycle life under High-rate Partial-state-of-Charge conditions. [ABSTRACT FROM AUTHOR]

Capacitive lithium-ion batteries with a dual-energy storage mechanism can provide a high energy and power density, which are constructed by the addition of slightly porous carbon. Here, the effect from porous carbon, such as the proportion, specific surface area, pore size and electrical conductivity, on the rate performance is systematically studied using hybrid electrodes with LiNi 0.6 Co 0.2 Mn 0.2 O 2 and activated carbon or carbon aerogel. Compared with LiNi 0.6 Co 0.2 Mn 0.2 O 2 electrodes, the hybrid electrodes demonstrate a lower resistivity, smaller electrochemical polarization, stronger rate capability and stable capacity retention. Furthermore, Adding carbon aerogel into LiNi 0.6 Co 0.2 Mn 0.2 O 2 material is more conducive to enhancing the rate performance when compared with activated carbon. The lithium-ion full capacitor battery configured of a hard carbon anode and LiNi 0.6 Co 0.2 Mn 0.2 O 2 -carbon aerogel delivers a capacity of 97.3 mAhg−1 at 10C with an energy density reaching 323.8 Wh∙kg−1 (vs. the cathode), showing bright prospects in energy storage system with both high specific energy and power densities. [ABSTRACT FROM AUTHOR]