Effect of Intrinsic Pore Distribution on Ion Diffusion Kinetics of Supercapacitor Electrode Surface

Abstract

The electrolyte ion diffusion kinetics have an important impact on electrochemical energy storage. Herein, we report the effect of the intrinsic porosity of NiCoP on accelerating electrolyte ion diffusion kinetics and accommodating volume expansion during the charge/discharge process. The pore distribution model of electrode/electrolyte was designed and optimized by the finite element simulation, demonstrating the visualization and quantitative analysis of the diffusion process of the electrode/electrolyte interface with intrinsic porous structure. When the pore area ratio reached 50.01%, the theoretical diffusion coefficient of 1.41 × 10–11 m2 s–1 would be conducive to the rapid diffusion of electrolytes. The electrode gained a specific capacity of 2805 F g–1 at a current density of 1 A g–1 based on the measured diffusion coefficient (1.79 × 10–10 m2 s–1), superior to 1.44-times that of the pristine electrode. The diffusion barriers of intrinsic porous NiCoP (3.19 eV) and conventional NiCoP (47.10 eV) were calculated by the density functional theory calculations, respectively. The intrinsic porous NiCoP was prepared by the hydrothermal treatment, annealing, and phosphating processes. The pore distribution was regulated by the concentration of NaHCO3 as a pore-forming additive. This work combines simulations and experiments to form a method to optimize diffusion kinetics at the electrode/electrolyte interface.

Benchmarking the ragone behaviour and power performance trends of pseudocapacitive batteries

“…Though Regime I is not realistically feasible, except through intentionally restricting electron diffusion and promoting ion diffusion, it does allow for an understanding of the distinct physical phenomena due to electrons and ions in the Ragone trends we shall explore in Regime II. Regime II is an optimized situation where electron diffusion is matched with ionic drift-diffusion to ensure charge balance [58][59][60][61][62]. Regime III is an unfavourable situation where the ionic drift-diffusion is severely restricted, leading to highly unfavourable resistive performance of the device and shall therefore not be considered in this study.…”

A self-supported porous NiMo electrocatalyst to boost the catalytic activity in the hydrogen evolution reaction

“…Compared with the planar structure of NiMo/NF, the porous structure of NiMo/Ni/NF can provide a larger space and surface area for the active material, which is conducive to the contact between the electrode surface and the electrolyte, and for providing a transport path for the electrolyte ions. 41…”

“…the contact between the electrode surface and the electrolyte, and for providing a transport path for the electrolyte ions. 41 To obtain more insight into the morphology of the prepared electrocatalyst, the catalyst samples separated on the nickel foam substrate were sonicated in ethanol. Fig.…”

Theoretical and Experimental Aspects of Electrocatalysts for Oxygen Evolution Reaction

“…Meanwhile, the hydrogen adsorption free energy of different adsorption sites also showed continuous step changes, suggesting that a continuous hydrogen overflow channel could be formed on the catalyst surface. The DFT method can even be combined with finite element simulations to demonstrate the electrochemical deposition kinetics process at the complex electrode/liquid electrolyte interface, thus providing an important reference for experimental and mechanism analysis [33–35] …”

“…The DFT method can even be combined with finite element simulations to demonstrate the electrochemical deposition kinetics process at the complex electrode/liquid electrolyte interface, thus providing an important reference for experimental and mechanism analysis. [33][34][35] Herein, this work aims to design and prepare efficient OER catalysts by combining DFT as a theoretical tool with material structure characterization/analytical methods. The design ideas of OER catalysts are based on the current three typical reaction mechanisms as a pointcut (Scheme 1), including adsorbate evolving mechanism (AEM), lattice oxygen-mediated mechanism (LOM), and unconventional bifunctional mechanism (BM).…”