Cobalt–Nickel Phosphate Composites for the All-Phosphate Asymmetric Supercapacitor and Oxygen Evolution Reaction

Abstract

Recently, design of cost-effective multifunctional electromaterials for supercapacitors and oxygen evolution reaction (OER) and enhancing their functionalities have become an emphasis in energy storage and conversion. Herein, a series of cheap and functional phosphate composites with different ratios of cobalt and nickel are synthesized using a simple polyalcohol refluxing method, and their excellent capacity and OER properties are systematically studied. Notably, owing to the different major role of Co and Ni elements in the phosphate composites for capacity and OER, the optimal electroconductibility, structural adjustment, electrochemical active sites, and activities for capacity and OER are obtained from the composites with the different ratios of Co/Ni. In addition, using high-capacity BiPO4 (BPO) as the negative electrodes, the new type of all-phosphate asymmetric supercapacitor (CNPO-40//BPO) shows a high energy density and reaches 36.84 W h kg–1 at a power density of 254.52 W kg–1. Its cyclic stability is also more excellent than that of the CNPO-40//AC device using commercial activated carbon as the negative electrodes. This study is beneficial to the more in-depth research on efficient dual-function electromaterials in capacity and OER and provides a high-efficient way to improve the practicality of asymmetric supercapacitors using the high-capacity Bi-based electromaterials as the negative electrodes.

Dumbbell-Shaped Ternary Transition-Metal (Cu, Ni, Co) Phosphate Bundles: A Promising Catalyst for the Oxygen Evolution Reaction

“…In recent times, several Earth-abundant transition metal-based OER catalysts with comparable activity have popped up, but they have failed to meet the benchmark required for extensive use. Among the different transition metals, nickel and cobalt in their different structural and chemical analogues have emerged to the situation and have shown great water oxidation activity. , Phosphides, , phosphonates, , phosphates, , hydroxides, , oxides, − and sulfides − of cobalt and nickel have been explored successfully as OER catalysts. Apart from these systems, different types of nanostructures, including the corresponding heterostructures, have also been studied for OER activity, but they have failed to meet the desired expectations.…”

ZIF-67 Derived Co2VO4 Hollow Nanocubes for High Performance Asymmetric Supercapacitors

“…This is because the active material does not have enough time to fully react with the electrolyte, and the utilization rate of the active material decreases [ 37 ]. Furthermore, the active material polarization effect becomes apparent as the scan rate increases [ 38 ]. The oxidation peaks at 0.15–0.2V and the reduction peaks at 0–0.5V can be clearly seen in the CV curves.…”

One-Step Rapid Conversion of Electroactive CoMnO Nanostructures Using a Deep Eutectic Solvent as the Template, Solvent, and Source

“…Ternary DES solvent was prepared by mixing the choline chloride (C 5 H 14 ClNO), glycerol, 25 and cobalt chloride (CoCl 2 •6H 2 O) precursors in the molar ratio of 1:2:0.06, as depicted in Scheme 1a. The mixture was transferred to a 50 mL beaker and heated at 75 °C at constant stirring conditions for 2 h. The obtained homogeneous solvent was sonicated in degassing mode for 10 min to remove formed air bubbles and stored in an airtight glass container.…”