Polypyrrole-Derived Carbon Coated NiCoMn Layered Double Hydroxides for High-Performance Supercapacitors

Abstract

Supercapacitors are considered to be a kind of promising electronic device and energy storage system for the new generation of electric transportation, and they have received more and more attention for their advantages. In this work, a polypyrrole-derived carbon layer coated with NiCoMn layered double hydroxides (NCM-LDH) is directly anchored on a Ni foam by applying a facile hydrothermal technique combined with the moderate temperature carbonization treatment. Benefiting from the structural merits and multiple electro-active components, the as-prepared lamellar structured NF/NiCoMn-LDH@PPy-C (NCM@PPy-C for short) demonstrates an enhanced pseudocapacitive performance of about 3157.78 F g–1 at 1 A g–1. Meanwhile, its cyclic longevity is improved, and the cyclic efficiency reaches up to 90.57% after 10000 cycles at 20 A g–1. The development of a ternary hybrid can be explained by (i) multiple active sites, (ii) enhanced electron and ion transport, and (iii) structural stability. Moreover, coupled with the active carbon negative electrode, an assembled asymmetric supercapacitor, NF/NCM@PPy-C//AC, exhibits high energy densities and power densities (53.55 Wh kg–1@448.3 W kg–1 and 25.65 Wh kg–1@2715.88 W kg–1) with 1.8 V as the improved operating voltage, and awesome cycling life, retaining around 73% of its capacitance after 10000 cycles. This study presents an approach for creating electrode materials for supercapacitors using layered double hydroxides of transition metals.

Six polyoxotungstate-based transition metal compounds for electrochemical capacitor application and a comparative analysis of factors affecting capacitances

“…5, the cyclic voltammetry (CV) tests of copper-based polyoxotungstate compounds 1–3 were conducted in a potential window ranging from −0.66 to 0.3 V. Unlike the rectangular CV curves observed in double-layer capacitors, the CV curves of compounds 1–3 show clear multiple pairs of reversible redox peaks, which indicate that 1–3 -GCEs exhibit faradaic capacitive characteristics. 67–69 For compounds 1 and 2 -based electrodes (Fig. 5a and b), the mean peak potentials E 1/2 = ( E pa + E pc )/2 are −0.078 V (I–I′), −0.369 V (II–II′), and −0.601 V (III–III′) for the 1 -based electrode, and −0.044 V (I–I′), −0.372 V (II–II′), and −0.602 V (III–III′) for the 2 -based electrode at 200 mV·s −1 .…”