Polipirol | cink ćelija sa vodenim rastvorom elektrolita i svojstvima superkapabaterije

Electrochemical oxidative polymerization at constant current density was used to produce polypyrrole (PPY) at graphite electrode from aqueous acidic electrolyte containing 0,1 mol dm-3 pyrrole and 1,0 mol dm-3 HCl. PPY electrode was than used as cathode while zinc electrode served as anode in electrochemical cell with an aqueous electrolyte containing 2,0 mol dm-3 NH4Cl and 1,1 mol dm-3 ZnCl2. The relevant electrochemical parameters of this cell were evaluated from electrochemical experiments. It was observed that charge of Zn|PPY cell started at voltage between 0,5 and 0,7 V and proceeded up to 1,5 V. Charge/discharge of the cell was dependent on charge/discharge current density with open circuit voltage of the fully discharged cell around 1,3 V. The estimated values of specific energy were between 46 and 68 W h kg-1 while specific power values were between 125 and 380 W kg-1, which suggested that Zn|PPY cell had “supercapaterry” behavior.Elektroda na bazi polipirola (PPY) dobijena je elektrohemijskom oksidativnom polimerizacijom na grafitnoj elektrodi u uslovima konstantne gustine struje. Kao elektrolit za sintezu, korišćen je vodeni rastvor 0,1 mol dm-3 pirola i 1,0 mol dm-3 HCl. Formirana je elektrohemijska ćelija u kojoj je elektroda na bazi PPY korišćena kao katoda dok je anoda bila elektroda od cinka, a elektrolit se sastojao od vodenog rastvora 2,0 mol dm-3 NH4Cl i 1,1 mol dm-3 ZnCl2. Procena relevantnih elektrohemijskih i električnih parametara ove ćelije bazirana je na elektrohemijskim eksperimentima. Utvrđeno je da je proces punjenja/pražnjenja zavisio od struje punjenja/pražnjenja, punejnje ćelije započinje na naponu između 0,5 i 0,7 V, a završava se na naponu od oko 1,3 V. Procenjene vrednosti energije bile su između 46 i 68 W h kg-1, dok se za specifičnu snagu dobijaju vrednosti između 125 i 380 W kg-1, što ukazuje na superkapabaterijska svojstva Zn|PPY ćelije

Application of polypyrolle based electrode materials in conversion and accumulation of electrical energy

Problematika ove doktorske disertacije izložena je u dve tematske celine. Prva je posvećena razmatranju elektrode na bazi elektrohemijski formiranog plipirola (PPY) kao elektrodnog materijala u konverziji energije, dok se druga celina odnosi na razmatranje elektrohemijski formirane elektrode na bazi PPY kao katodnog i anodnog materijala za primenu u akumulaciji električne energije na bazi vodenih rastvora elektrolita. Elektroda na bazi PPY formirana je anodnom oksidativnom polimerizacijom pirola na elektrodi od staklastog ugljenika u uslovima konstantne gustine struje (galvanostatski). Za potrebe razmatranja fotoelektrohemijskog ponašanja elektrode na bazi PPY, elektrohemijska sinteza je sprovedena u vodenom rastvoru elektrolita koji je sadržavao pored pirola natrijum-nitrat i azotnu kiselinu. Polimerizacija je ostvarena anodnom gustinom struje od j = 1,0 mA cm-2 u trajanju od 3 h. Za razmatranje PPY kao elektrodnog materijala u akumulaciji električne energije, elektrode na bazi PPY dobijene su iz vodenog rastvora 1,0 mol dm-3 HCl hlorovodonične kisline kada su razmatrane kao katode u sistemu ZnPPY, dok je za razmatranje u sistemima PPYPbO2, odnosno PbSO4PPY korišćen vodeni elektrolit 1,0 mol dm-3 H2SO4. Elektrohemijsaka polimerizacija je ostvarena u galvnostatskim uslovima, gustinom struje od 2 mA cm–2 u trajanju od 1 h i 0,3 h za sisteme PPYPbO2 i PbSO4PPY respektivno. Za potrebe fotoelektrohemijskih eksperimentata formirane su elektrode na bazi bakar-sulfida, i PPY modofikovane bakar-sulfidom, korišćenjem postupka naizmenične jonske adsorpcije i reakcije (SILAR). Kao rastvor katjonskog prekursora korišćen je vodeni rastvor 0,050 mol dm-3 bakar(II) - nitrata, dok je za formiranje sulfida korišćen rastvor 0,10 mol dm-3 natrijum - sulfida. Ispitana su fotoelektrohemijska svojstva elektrode od PPY, bakar-sulfida i PPY modifikovane bakar-sulfidom, u potenciostatskim uslovima u anodnoj i katdnoj oblsti, u mraku i pri osvetljenju, u vodenom elektrolitu sastava 0,5 mol dm-3 NaNO3 i 0,2 mol dm-3 tiouree i 0,025 mol dm-3 Na2S. Ispitivane su elektrohemijske i električne karakteristike sistema ZnPPY, PPYPbO2 i PbSO4PPY. Utvrđeno je da ZnPPY ćelija sa vodenim rastvorom elektrolita sastava 2,0 mol dm-3 NH4Cl i 1,1 mol dm-3 ZnCl2, ima prosečan napon pražnjenja od 0,85 V i specifični kapacitet pražnjenja od 52 mAh g-1. PPYPbO2 ćelija sa vodenim rastvorom elektrolita sastava 1,0 mol dm-3 H2SO4 i 0,5 mol dm-3 (NH4)2SO4 ima prosečni napon pražnjenja od 0,9 V i specifični kapacitet pražnjenja od 88 mAh g-1. Prosečan napon pražnjenja za PbSO4PPY ćeliju iznosio je 0,65 V, a specifični kapacitet pražnjenja 50 mAh g-1. Specifična energija pražnjenja do radnog potencijala od 0,5 V, efikasnost iskorišćenja energije i specifična snaga su pocenjenje na 45 mWh g-1 (56%), 326 mW g-1 za Zn|PPY ćeliju; 76 mWh g-1 (45%), 584 za PPY|PbO2 ćeliju 37 mWh g-1 (51%), 574 mWh g-1 za PbSO4|PPY ćeliju. Na osnovu ovih vrednosti pomenute ćelije su svrstane u tzv. superkapabaterije.The problematics of this dissertation is dedicated to application of electrochemically formed polypyrrole as electrode material in conversion of electrical energy and cathodic and anodic material in systems for accumulation of electrical energy with aqueous electrolytes. In both cases PPY electrode was form by electrochemical anodic polymerization of pyrrole monomer on glassy carbon electrode at constant current (galvanostatially). Depending on the further application, different composition of electrolytes was used, for PPY used in photoelectrochemical investigations, nitrate based electrolyte was used, while chloride based and sulfate based electrolytes were used for application of PPY as electrode material in electrochemical cells: ZnPPY and PPYPbO2, PbSO4PPY respectively. Coper-sulfate electrode and coper-sulfate modified PPY electrode were formed by SILAR process on glassy carbon and PPY electrochemically formed on glassy carbon electrode. Cationic precursor solution was 0.050 mol dm-3 copper (II) – nitrate, and 0.10 mol dm-3 sodium sulfide as a solution of anionic precursor. Photo electrochemical behavior of these electrodes was investigated at constant anodic and cathodic potentials in dark and under illumination in water electrolyte consisted of 0.5 mol dm-3 NaNO3, 0.2 mol dm-3 tiourea and 0.025 mol dm-3 Na2S. Electrochemical and electrical characteristics of the cells based on PPY based electrode comined zinc, lead oxide and lead sulfate electrodes in aqouous based electrolyte were determined. Zn|PPY cell in which PPY based electrode served as cathode and zinc electrode as anode with electrolyte composed of 2.0 mol dm-3 NH4Cl and 1.1 mol dm-3, exibited the open circuit voltage of 1.3 V, average discharge voltage of 0.85 V and specific discharge capacity of 52 mAh g-1. PPY|PbO2 cell in which PPY based electrode whas anode and PbO2 as chatode with electrolyte composed of 1.0 mol dm-3 H2SO4 and 0.5 M (NH4)2SO4 had the open circuit voltage of 1.5 V, average discharge voltage of 0.9 V, and specific discharge capacity of 88 mAh g-1. PbSO4|PPY cell with PPY cathode and lead sulfate anode with the same sulfateelectrolyte had the open circuit voltage of 1.1 V, average discharge voltage of 0.65 V and specific discharge capacity of 50 mAh g-1. The specific discharge energy to the useful discharge potentials of ~ 0.5 V, charge-discharge energy efficiency, as well as specific power, were estimated to 45 mWh g-1 (56%), 326 mW g-1 for Zn|PPy cell; 76 mWh g-1 (45%), 584 for PPY|PbO2 cell, and 37 mWh g-1 (51%), 574 mWh g-1 for PbSO4|PPY cell. Based on estimated specific energy and power, the investigated cells were classified as “supercapattery” type of electrochemical power sources

The initial characteristics of the polypyrrole based aqueous rechargeable batteries with supercapattery characteristics

The electrochemically synthesized polypyrrole (PPy) is investigated as a possible active material of the low-cost aqueous based secondary power sources in combination with zinc, lead oxide, and lead sulfate. The discharge capacity of the polypyrrole in the chloride-based electrolyte (for the Zn|PPy cell) is in the range 110 mAh g −1 of PPy, while in the sulfate-based electrolyte ∼150 mAh g −1 of PPy (for the PbSO 4 |PPy and PPy|PbO 2 cells), which is close to the theoretically calculated values. Electrochemical and electrical parameters, reactions in the cells, specific capacity, specific capacitance, energy, and power, for the Zn|PPy, PPy|PbO 2 and PbSO 4 |PPy cells are determined. In addition, the energy efficiency, for the considered systems is estimated. Obtained values of the specific power and energy, could classified investigated systems as a battery type hybrid superacapacitors or “supercapattery”.Published version [http://technorep.tmf.bg.ac.rs/handle/123456789/4221]This is the peer-reviewed version of the following article: Grgur B, Janačković M, Jugović B, Gvozdenović M. The initial characteristics of the polypyrrole based aqueous rechargeable batteries with supercapattery characteristics. in Materials Science and Engineering B-Advanced Functional Solid-State Materials. 2019;243:175-182. [doi:10.1016/j.mseb.2019.04.013

The improved photooxidation stability of the SILAR deposited copper sulfide on polypyrrole

The copper sulfide is successfully deposited onto electrochemically formed polypyrrole, by successive ion-adsorption and reaction (SILAR) processes. The photoelectrochemical behavior of the polypyrrole, copper sulfide and copper sulfide modified polypyrrole are investigated in the sulfide based solution, under cathodic and anodic polarization. The improvement of the photooxidation stability, as well as activity of copper sulfide modified polypyrrole is achieved. Such behavior is explained by recombination of electrons from Cu2-xS conducting band with the holes of the PPy LUMO