Controlled synthesis of three-phase NixSy/rGO nanoflake electrodes for hybrid supercapacitors with high energy and power density

Abstract

Composition design and morphology control of electrode materials are effective strategies to enhancing the specific capacity, rate capability, and cycling life of electrochemical energy storage devices. Here we report our findings in the design and synthesis of a three-phase nickel sulfide (NiS-Ni 3 S 2-Ni 3 S 4 , denoted as TP-Ni x S y) with 3D flower-like architecture assembled from interconnected nanoflakes, which delivers a specific capacity of 724 C g-1 at a current density of 1 A g-1. When integrated with reduced graphene oxide (rGO), a TP-Ni x S y /rGO composite nanoflake electrode, derived from a hydrothermal process, demonstrates not only higher specific capacity (807 C g-1 at 1 A g-1) but also better rate capability (~72% capacity retention as the current density was increased from 1 to 20 A g-1). Moreover, a hybrid energy storage device, constructed from a TP-Ni x S y /rGO positive electrode and a graphene-based negative electrode, shows a high energy density of 46 Wh kg-1 at a power density of 1.8 kW kg-1. It retained an energy density of 32 Wh kg-1 at power density of 17.2 kW kg-1 , demonstrating its viability and potential for practical applications.

Flexible Solid‐State Asymmetric Supercapacitors Based on Nitrogen‐Doped Graphene Encapsulated Ternary Metal‐Nitrides with Ultralong Cycle Life

“…The electrode materials are playing a vital role to enhance the energy density of SCs by increasing its operating potential window. The electrode materials of SCs should possess high catalytic activity, excellent electrical conductivity, extraordinary surface area, exclusive porous architecture, outstanding mechanical stability, and low production cost . Moreover, the fabrication of asymmetric SCs (ASCs) has recently drawn research interest among scientists, since it can integrate battery‐type Faradic electrode as energy sources as well as a capacitor‐type electrode as power sources to enhance the energy density of the SCs .…”

“…The electrode materials of SCs should possess high catalytic activity, excellent electrical conductivity, extraordinary surface area, exclusive porous architecture, outstanding mechanical stability, and low production cost . Moreover, the fabrication of asymmetric SCs (ASCs) has recently drawn research interest among scientists, since it can integrate battery‐type Faradic electrode as energy sources as well as a capacitor‐type electrode as power sources to enhance the energy density of the SCs . Generally, carbon‐based electrical double layer capacitive (EDLC) materials have been extensively used in industrial sectors due to the high electrical conductivity, large specific surface area, remarkable electrochemical stability, and cost‐effectiveness .…”

Effect of Graphene Oxide Thin Film on Growth and Electrochemical Performance of Hierarchical Zinc Sulfide Nanoweb for Supercapacitor Applications

“…The possible charge storage mechanism, as shown in Figure , indicated that OH −1 moves easily from one electrode surface to another electrode, which may result because of the optimum conductivity and suitable large specific surface area of the electrode surface available during the charge and discharge process . The specific capacitance was computed using the following Equation , …”

Construction of (Ni, Cu) Se2//Reduced Graphene Oxide for High Energy Density Asymmetric Supercapacitor

“…To ensure the veracity of measurement, the charge stored in asymmetric supercapacitor was balanced, as the equation of Q+=Q−, where Q+ and Q− stand for the charge stored in the positive and negative electrode, respectively, and the equation of Q=Cm‐UM=CA+UA, where the Cm‐, CA+, U, M and A stand for the mass specific capacitance and areal specific capacitance (F g −1 and F cm −2 respectively), the potential window, effective mass and effective area of work electrode individually. The calculation of energy density and power density of asymmetric supercapacitors follows Equations (6) and : …”