Energy Harvesting by Nickel Prussian Blue Analogue Electrode in Neutralization and Mixing Entropy Batteries

Abstract

Some industries usually reduce the concentration of protons in acidic wastewater by conducting neutralization reactions and/or adding seawater to industrial effluents. This work proposes a novel electrochemical system that can harvest energy originating from entropic changes due to alteration in the concentration of sodium ions along wastewater treatment. Preparation of a self-assembled material from nickel Prussian blue analogue (NPBA) was the first step to obtain such electrochemical system. Investigation into the electrochemical properties of this material helped to evaluate its potential use in neutralization and mixing entropy batteries. Assessment of parameters such as the potentiodynamic profile of the current density as a function of the concentration of protons and sodium ions, charge capacity, and cyclability as well as the reversibility of the sodium ion electroinsertion process aided estimation of the energy storage efficiency of the system. Frequency-domain measurements and models and the proposed charge compensation mechanism provided the rate constants at different dc potentials. After each charge/discharge cycle, the NPBA electrode harvested 12.4 kJ per mol of intercalated sodium ion in aqueous solutions of NaCl at concentrations of 20 mM and 3.0 M. The full electrochemical cell consisted of an NPBA positive electrode and a negative electrode of silver particles dispersed in a polypyrrole electrode. This cell extracted 16.8 kJ per mol of intercalated ion after each charge/discharge cycle. On the basis of these results, the developed electrochemical system should encourage wastewater treatment and help to achieve sustainable growth.

Electrochemical Systems for Renewable Energy Conversion from Salinity and Proton Gradients

“…67,68 An electrode consisting of silver particles dispersed in PPy (Ag/PPy) was prepared and used as the negative electrode in a MEB system. 61 A full cell consisting of NiHCF (positive) and Ag/PPy (negative) electrodes afforded 16.8 kJ per mol of sodium ion for each electrochemical cycle as demonstrated by charge/ discharge curves ( Figure 9). The negative electrode removed and provided chloride anions during the oxidation and the reduction processes, respectively.…”

“…In fact, Gomes et al 61 used thin NiHCF films to check the applicability of PBA in MEB. The average anodic and cathodic peak potentials relative to the potential measured for the electrolytic 20 mM NaCl solution as a function of the molar concentration logarithm demonstrated that it is possible to use this electrode to convert energy from a highly saline water source (Figure 8a): the authors extracted 12.4 kJ per mol of sodium ion after a charge/ discharge cycle, which is equivalent to the area between the discharge curve in a 3.0 M NaCl aqueous solution and the charge curve in a 20 mM NaCl aqueous solution (Figure 8b).…”

“…62 In the early 1970s, it was accidentally ) for the NiHCF film allowed an electrochemical energy extraction of 12.4 kJ per mol of sodium ion per cycle. Adapted from Gomes et al 61 discovered that metals and polyacetylene doped with iodine display similar conductive properties. Since then, a considerable quantity of new conductive polymers have been synthesized.…”

Salinity‐Difference‐Driven Power Generation by a Hybrid Capacitive Approach

“…proposed a pseudocapacitor based on the ion intercalation/de‐intercalation mechanism for energy‐harvesting and employed transition metal oxides as cation electrodes with Ag for the anion electrode to enhance the performance of this pseudocapacitor. Other cation electrodes have also been studied, such as hexacyanoferrate compounds . However, this battery‐like approach is challenged by the gradual leaching loss of Ag, which is an expensive material with limited availability.…”

“…Other cation electrodes have also been studied, such as hexacyanoferrate compounds. [17][18][19] However, this battery-like approachi sc hallenged by the gradual leachingl oss of Ag, which is an expensive material with limited availability.R ecently,Y oon et al [20] proposed an asymmetric capacitor that used sodium manganese oxides and AC as electrodes and ion-exchange membranes,w hichr esulted in an expensive device.Ah ybrid capacitor, [21][22][23] also known as as econd-generation supercapacitor that typically couples insertion-and adsorption-type electrodes and combines two charge-storage mechanisms,h as attracted much attention becauseo fi ts high energya nd powerd ensities.A ccordingly,t his concept has been introduced into capacitive deionizationf or desalination. [24] In this work, we propose ac ost-effective technique called "hybrid capacitive mixing" (HCM) that extracts SGE without using expensivem embranes or Ag.…”