Endah Retno Dyartanti

Ionic Conductivity and Cycling Stability Improvement of PVDF/Nano-Clay Using PVP as Polymer Electrolyte Membranes for LiFePO4 Batteries

In this paper, we present the characteristics and performance of polymer electrolyte membranes (PEMs) based on poly(vinylidene fluoride) (PVDF). The membranes were prepared via a phase-inversion method (non-solvent-induced phase separation (NIPS)). As separators for lithium battery systems, additive modified montmorillonite (MMT) nano-clay served as a filler and poly(vinylpyrrolidone) (PVP) was used as a pore-forming agent. The membranes modified with an additive (8 wt % nano-clay and 7 wt % PVP) showed an increased porosity (87%) and an uptake of a large amount of electrolyte (801.69%), which generated a high level of ionic conductivity (5.61 mS cm−1) at room temperature. A graphite/PEMs/LiFePO4 coin cell CR2032 showed excellent stability in cycling performance (average discharge capacity 127 mA h g−1). Based on these results, PEMs are promising materials to be used in Polymer Electrolyte Membranes in lithium-ion batteries.

Study on characteristics of PVDF/nano-clay composite polymer electrolyte using PVP as pore-forming agent

Polyvinylidene fluoride (PVDF) based polymer electrolytes have a high dielectric constant, which can assist in greater ionization of lithium salts. The main advantages of PVDF are its durability in long battery operation and its ability to be a good ion conductor. However, the limitation of this polymer is its crystalline molecular structure. Dispersing nano-particles in the polymer matrix may improve the characteristics of the PVDF polymer. This paper aims to investigate the impact of nano-clay addition on the characteristics of PVDF polymer to be used as a polymer electrolyte membrane. In addition, the effect of poly(vinyl pyrrolidone) (PVP) is also investigated. The membrane was prepared by phase separation method whereas the polymer electrolyte membranes was prepared by immersing into 1 M lithium hexafluorophosphate (LiPF6) in ethylene carbonate/dimethyl carbonate (EC/DMC) electrolytes for 1 h. The membranes were characterized by scanning electron microscope (SEM), porosity and electrolyte uptake and ...

Preparation and characterization of nanocomposite polymer electrolytes poly(vinylidone fluoride)/nanoclay

Polymer electrolytes are defined as semi solid electrolytes used as separator in lithium ion battery. Separator used as medium for transfer ions and to prevent electrical short circuits in battery cells. To obtain the optimal battery performance, separator with high porosity and electrolyte uptake is required. This can reduce the resistance in the transfer of ions between cathode and anode. The main objective of this work is to investigate the impact of different solvent (Dimethyl acetamide (DMAc), N-methyl-2-pyrrolidone (NMP) and dimethyl formamide (DMF)), pore forming agent poly(vinylpyrolidone) (PVP) and nanoclay as filler in addition of membrane using phase inversion method on the morphology, porosity, electrolyte uptake and degree of crystallinity. The membrane was prepared by the phase inversion method by adding PVP and Nanoclay using different solvents. The phase inversion method was prepared by dissolving Nanoclay and PVP in solvent for 1-2 hours, and then add the PVDF with stirring for 4 hours at...

Synthesis of TiO2 by electrochemical method from TiCl4 solution as anode material for lithium-ion batteries

Metal oxide combined with graphite becomes interesting composition. TiO2 is a good candidate for Li ion battery anode because of cost, availability of sufficient materials, and environmentally friendly. TiO2 gravimetric capacity varied within a fairly wide range. TiO2 crystals form highly depends on the synthesis method used. The electrochemical method is beginning to emerge as a valuable option for preparing TiO2 powders. Using the electrochemical method, the particle can easily be controlled by simply adjusting the imposed current or potential to the system. In this work, the effects of some key parameters of the electrosynthesis on the formation of TiO2 have been investigated. The combination of graphite and TiO2 particle has also been studied for lithium-ion batteries. The homogeneous solution for the electrosynthesis of TiO2 powders was TiCl4 in ethanol solution. The electrolysis was carried out in an electrochemical cell consisting of two carbon electrodes with dimensions of (5 × 2) cm. The electrod...

Phase transformation of TiO2 powder prepared by TiCl4 hydrolysis-electrolysis

Metal oxide combined with graphite becomes an interesting composition. TiO2 is a good candidate for Li ion battery anode because of low cost, availability sufficient, and environmentally friendly. The form of TiO2 crystals is highly depended on the synthesis method used. The electrochemical method is beginning to emerge as a valuable option for preparing TiO2 powders. Using the electrochemical method, the particle phase can easily be controlled by simply adjusting the imposed current or potential to the system. The present work aims to investigate the effects of electrode distance in the electrolysis of TiCl4 solution to the phase transformation of anatase to rutile. The homogeneous solution for the electro-synthesis of TiO2 powders was TiCl4 in ethanol solution. The electrolysis was carried out in an electrochemical cell consisting of two carbon electrodes with dimensions of (5×2) cm. The electrodes were set parallel with various distances of 2.6 cm, 3 cm, and 4 cm between the electrodes and were immerse...

Improving lithium-ion battery performances by adding fly ash from coal combustion on cathode film

A lithium battery is composed of anode, cathode and a separator. The performance of lithium battery is also influenced by the conductive material of cathode film. In this research, the use of fly ash from coal combustion as conductive enhancer for increasing the performances of lithium battery was investigated. Lithium iron phosphate (LiFePO4) was used as the active material of cathode. The dry fly ash passed through 200 mesh screen, LiFePO4 and acethylene black (AB), polyvinylidene fluoride (PVDF) as a binder and N-methyl-2-pyrrolidone (NMP) as a solvent were mixed to form slurry. The slurry was then coated, dried and hot pressed to obtain the cathode film. The ratio of fly ash and AB were varied at the values of 1%, 2%, 3%, 4% and 5% while the other components were at constant. The anode film was casted with certain thickness and composition. The performance of battery lithium was examined by Eight Channel Battery Analyzer, the composition of the cathode film was examined by XRD (X-Ray Diffraction), and...

PROFIL FERMENTASI PADA PRODUKSI MINYAK MIKROALGA MENGGUNAKAN Nannochloropsis oculata DALAM MEDIUM BG-11

Abstract: The Government has launched a substitution program of petroleum based oil with renewable energy sources. One of the programs implemented is substitution of diesel oil by biodiesel. However, there is a problem with biodiesel raw material resources, i.e. alternative of crude palm oil avoiding competition of food utilization. The prospective one is microalgae oil. The objective of this study is to explore fermentation profile of Nannochloropsis oculata growing in medium BG-11. Experiments used a bioreactor equipped with a gas absorber and N. oculata cultured in medium BG-11. While culturing N. oculata, oxygen was supported in the gas absorber by circulating the medium through bioreactor – absorber – bioreactor. Sampling was carried out periodically once a day (24 hours) and analysis of samples included cell temperature, salinity, pH, cell dry weight, and oil content. The data were presented in a graphical form of the parameter profile. Keywords: microalgae, fermentation profile, Nannochloropsis oculata., oil content

Effect of LiFePO4 Cathode Thickness on Lithium Battery Performance

Lithium ion battery is composed of three main parts, i.e. cathode, anode and electrolyte. In this work, we investigated the effect of LiFePO4 cathode composite’s thickness on performances of lithium battery. LiFePO4 cathode was prepared in a slurry that consisted of lithium iron phosphate (LiFePO4) powder as active material, acetylene black as conductive additive, polyvinylidene fluoride (PVDF) as binder, and N-methyl-2-pyrrolidone (NMP) as solvent. The slurry was then deposited on the aluminum substrate using doctor blade method in different thickness. The cathode layers were deposited with the thickness of 150, 200, 250 & 300 μm. The structure characterization of the material was analyzed by XRD, while the material’s morphology was analyzed by Scanning Electron Microscope (SEM). Performances of lithium ion battery with LiFePO4 cathode were evaluated using charge-discharge cycle test. It is found that battery made of cathode layer with 250 μm thickness shows the best performances.