Uniform thin film based polymer separators for rechargeable Li-ion batteries

Battery separator’s main function is to prevent physical contact of the electrodes while permitting ions to flow freely. They itself does not participate in any cell reactions, however, its properties significantly determine the performance and safety of the batteries. For high energy and power densities, the separator is required to be very thin and highly porous, while it adversely affects the safety and cycle life of the battery as a result of the reduced mechanical strength. The safety requirement is a top priority for rechargeable Li-ion batteries, especially these used in hybrid electric vehicles and power tools. Battery separators need to have excellent porosity, as well as low cost, lightness and durability

Usage of Layer-by-Layer Method for Obtaining Polyelectrolyte Multilayer Films Containing Transition Metal Cations

The alternating layer-by-layer deposition of oppositely charged polyelectrolytes at solid substrates is an attractive technique for preparation of nanostructured surface coatings of controlled thickness. This paper reports the results of covalently binding of cobalt (II) and copper (II) ions within polyelectrolyte multilayers (PEMs). We have used polycation as polyethyleneimine (BPEI) and polyanion as poly(acrylic acid) (PAA) and the electrostatic layer-by-layer assembly technique to make uniform thin film coating on solid template with controllable thickness. Thermodynamic characteristics as stability constant, free Gibbs energy, enthalpy and entropy of complex forming processes of these polyelectrolytes with Co(II) and Cu(II) cations in solution were calculated by modified method of Bjerrum. The correlation between log ОІ values and some of the fundamental properties of the metal ions are discussed. It was found that the ratio of Me:L in water solvent is 1:4 in the investigating systems Cu2+:BPEI and Co2+:BPEI and in the systems CРѕ2+:PAA and CРѕ2+:PAA - 1:2. PEMs were deposited onto silicon wafers, glass slides, or coated on silica oxide particles. Dipping solutions of different pH were used in order to find the optimum conditions for absorbing maximum amount of metal cations. These PEMs films are found to offer high capacity and selectivity for copper over cobalt in both acidic and alkaline media. Preliminary investigation have shown that metal containing PEMs has catalytic activity for oxidation of toluene with molecular in mild condition. The alternating layer-by-layer deposition of oppositely charged polyelectrolytes at solid substrates is an attractive technique for preparation of nanostructured surface coatings of controlled thickness. This paper reports the results of covalently binding of cobalt (II) and copper (II) ions within polyelectrolyte multilayers (PEMs). We have used polycation as polyethyleneimine (BPEI) and polyanion as poly(acrylic acid) (PAA) and the electrostatic layer-by-layer assembly technique to make uniform thin film coating on solid template with controllable thickness. Thermodynamic characteristics as stability constant, free Gibbs energy, enthalpy and entropy of complex forming processes of these polyelectrolytes with Co(II) and Cu(II) cations in solution were calculated by modified method of Bjerrum. The correlation between log ОІ values and some of the fundamental properties of the metal ions are discussed. It was found that the ratio of Me:L in water solvent is 1:4 in the investigating systems Cu2+:BPEI and Co2+:BPEI and in the systems CРѕ2+:PAA and CРѕ2+ :PAA - 1:2. PEMs were deposited onto silicon wafers, glass slides, or coated on silica oxide particles. Dipping solutions of different pH were used in order to find the optimum conditions for absorbing maximum amount of metal cations. These PEMs films are found to offer high capacity and selectivity for copper over cobalt in both acidic and alkaline media. Preliminary investigation have shown that metal containing PEMs has catalytic activity for oxidation of toluene with molecular in mild condition

High energy density ecologically friendly batteries for grid connection of renewable sources and electric vehicles

Aqueous Rechargeable lithium batteries (ARLBs) could be an attractive alternative to bypass safety issues of lithium-ion batteries with organic electrolyte. Moreover, the fast lithium diffusion in aqueous electrolyte media could allow for the operations under high electric current conditions required especially for high power supply [1]. In 1994, J. Dahn et al reported a VO2/LiMn2O4 rechargeable aqueous battery [2]. However, this type of batteries had serious issues with cyclability. In this work, we report for the first time on a system comprising in an aqueous electrolyte, and on large-scale ARLB based on this concept with enhanced cycle performance and energy density

High energy density ecologically friendly batteries for grid connection of renewable sources and electric vehicles

Aqueous Rechargeable lithium batteries (ARLBs) could be an attractive alternative to bypass safety issues of lithium-ion batteries with organic electrolyte. Moreover, the fast lithium diffusion in aqueous electrolyte media could allow for the operations under high electric current conditions required especially for high power supply [1]. In 1994, J. Dahn et al reported a VO2/LiMn2O4 rechargeable aqueous battery [2]. However, this type of batteries had serious issues with cyclability. In this work, we report for the first time on a system comprising in an aqueous electrolyte, and on large-scale ARLB based on this concept with enhanced cycle performance and energy density

Development of novel sulfur/carbon cathode composites using spray pyrolysis and study of their electrochemical performance in lithium-sulfur batteries

The eminent global energy crisis and growing ecological concerns in the past two decades have led to intensive development in the fields of green transportation such as electric and hybrid electric vehicles (HEV), as well as clean energy sources such as wind and solar power. These technologies demand low cost, safe, and environmentally friendly energy storage systems. Therefore, development of novel economically feasible and ecologically friendly high performance batteries is crucial. Lithium/ sulfur (Li/S) batteries have the highest energy density (2600 Wh/kg) and theoretical capacity (1672 mAh/g) among all known systems [1,2]

Silica from Kazakhstan Rice Husk as an Anode Material for LIBs

This paper reports the synthesis of the silica (SiO2) from Kyzylorda rice husk (RH) and investigation of its electrochemical behaviour as an anode material for the lithium-ion battery. Rice husk, considered as agricultural waste material, contains a substantial amount of amorphous silica, carbon, and minor other mineral composition, which have potential industrial and scientific applications. Due to the high theoretical capacity of silicon (4200 mAh g-1) and silicon dioxide (1965 mAh g-1), Si-containing compounds are considered as a promising candidate for a new generation of anode materials for lithium-ion batteries. In this work, the technology of amorphous SiO2 extraction from Kyzylorda region rice husk is developed. The silica powder was obtained by burning the rice husk and treating the obtained ash with the sodium hydroxide and hydrochloric acid. The extracted SiO2 and intermediate products were studied by the SEM, XRD, XRF, XPS, TGA in comparison with commercial silica. The RH of the Kyzylorda region has 12% of Si. The electrochemical characteristics of assembled coin cell type battery were tested by using cyclic voltammetry and galvanostatic charge/discharge cycling. Results show that silica synthesized from agriculture waste has the same performance as commercial analog. The initial discharge capacity of the battery with synthesized silicon dioxide was 1049 mAhg-1. The reversible discharge capacity in the second and subsequent cycles is about 438 mAhg-1

Efficient Polysulfides Conversion Kinetics Enabled by Ni@CNF Interlayer for Lithium Sulfur Batteries

Recent advances in the development of lithium-sulfur batteries (Li-S) demonstrated their high effectiveness owing to their tremendous theoretical specific capacity and high theoretical gravimetrical energy. Nevertheless, the potential commercialization of Li-S is significantly held by the insulating nature of sulfur and complicated RedOx reactions during the electrochemical charge-discharge processes. This paper presents nickel nanoparticles embedded carbon nanofibers interlayer (Ni@CNF) between a cathode and a separator as an additional physical barrier against lithium polysulfides shuttle for their efficient conversion during the charge-discharge cycling. Furthermore, the interlayer provides an auxiliary electron pathway with subsequent lowering of the charge transfer resistance. The electrochemical analysis of a Li-S cell with the Ni@CNF interlayer demonstrated high initial discharge capacities of 1441.2 mAh g-1 and 1194.2 mAh g-1 at 0.1 and 1.0 C rates, respectively, with remarkable capacity retention of ~83% after 100 cycles. This study revealed the advantageous impact of Ni@CNF towards solving the major issues of lithium-sulfur batteries, i.e., sluggish kinetics and the shuttle effect

NANOSCALE THERMAL TRANSPORT AND ELASTIC PROPERTIES OF LITHIATED AMORPHOUS SI THIN FILMS

Silicon is the heart of modern electronics and due to it is high theoretical storage capacity it also attracted much attention as a possible anode material for the next generation Li-ion batteries. Heat conduction is one of the major properties in the development of Li-ion batteries for energy conversion systems and it is of paramount importance to have comprehensive understanding of heat dissipation on the scale of electrochemical storage device. In this work we report ex-situ study of nanoscale thermal transport and elastic properties of lithiated amorphous Si (a-Si) anode films using picosecond time-domain thermoreflectance (TDTR). Radio frequency (rf) magnetron sputtering was used to deposit a ∼330 nm thick a-Si films on glass substrate. Near-surface nanoscale thermal transport measurements show 40% increase in thermal conductivity of a-Si upon electrochemical lithiation reaching up to 2.2 W m-1K−1. This sizeable increase might be due to Li+ ion-mediated heat conduction during lithiation process. The standard deviation of measured thermal conductivity was slightly higher likely due to inhomogeneous lateral and cross-plane Li+ ions distribution in the sub-surface film region. Nanosecond laser pulsed induced surface acoustic waves (SAWs) measurements showed the decrease in Young’s modulus after lithiation on nanometre scale, which is attributed to volumetric expansion of Si upon Li+ ions insertio

Noneluting Enzymatic Antibiofilm Coatings

We developed a highly efficient, biocompatible surface coating that disperses bacterial biofilms through enzymatic cleavage of the extracellular biofilm matrix. The coating was fabricated by binding the naturally existing enzyme dispersin B (DspB) to surface-attached polymer matrices constructed via a layer-by-layer (LbL) deposition technique. LbL matrices were assembled through electrostatic interactions of poly­(allylamine hydrochloride) (PAH) and poly­(methacrylic acid) (PMAA), followed by chemical cross-linking with glutaraldehyde and pH-triggered removal of PMAA, producing a stable PAH hydrogel matrix used for DspB loading. The amount of DspB loaded increased linearly with the number of PAH layers in surface hydrogels. DspB was retained within these coatings in the pH range from 4 to 7.5. DspB-loaded coatings inhibited biofilm formation by two clinical strains of <i>Staphylococcus epidermidis</i>. Biofilm inhibition was ≥98% compared to mock-loaded coatings as determined by CFU enumeration. In addition, DspB-loaded coatings did not inhibit attachment or growth of cultured human osteoblast cells. We suggest that the use of DspB-loaded multilayer coatings presents a promising method for creating biocompatible surfaces with high antibiofilm efficiency, especially when combined with conventional antimicrobial treatment of dispersed bacteria