Andrzej P. Nowak

Aquatic biomass containing porous silica as an anode for lithium ion batteries

A composite electrode was manufactured by pyrolysis of Red Algae (Polysiphonia fucoides) covered by diatoms (Diatomophyceae). Electrodes were tested as a half cell with capacity of 500 mA h g−1 after 80 cycles. XPS analysis shows formation of lithium silicate under reduction of silica in an aprotic electrolyte containing LiPF6 salt.

Tin oxide nanoparticles from laser ablation encapsulated in a carbonaceous matrix – a negative electrode in lithium-ion battery applications

This report concerns carbonaceous electrodes doped with tin(II) oxide nanoparticles. Tin nanoparticles are obtained by pulsed laser ablation in water. Crystalline nanoparticles have been encapsulated in a carbonaceous matrix formed after pyrolysis of a mixture consisting of tin/tin(IV) oxide nanoparticles and gelatine. The obtained material is characterized by means of X-ray diffraction, selected area diffraction, scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray analysis. Battery charging/discharging tests exhibit a capacity of 580 mA h g−1 for current densities of 100 mA g−1. The cycling performance of the material suggests that the tested nanocomposite can be used as an anode for lithium-ion batteries.

Biosilica from sea water diatoms algae—electrochemical impedance spectroscopy study

Here, we report on an electrochemical impedance study of silica of organic origin as an active electrode material. The electrode material obtained from carbonized marine biomass containing nanoporous diatoms has been characterised by means of XRD, IR, SEM and EIS. Different kinds of crystallographic phases of silica as a result of thermal treatment have been found. The electrode is electrochemically stable during subsequent cyclic voltammetry measurements taken in the potential range from 0.005 up to 3.0 V vs. Li/Li+. The material has been found to exhibit high charge capacitance of 521 mAh g−1 being cycled at a rate C/20 with capacity retention of about 97%. Electrochemical impedance spectroscopy performed at an equilibrated potential E = 0.1 V in the temperature range 288–294 K discloses low charge transfer resistivity and low diffusional impedance.

ELECTROCHEMICAL ACTIVITY OF COMPOSITE MATERIAL POLY(3, 4-ETHYLENEDIOXYTHIOPHENE) MODIFIED BY SILVER HEXACYANOFERRATE

An electrochemical way to prepare poly(3, 4-ethylenedioxythiophene) (pEDOT) modified by silver hexacyanoferrate (Aghcf) is presented. The electrode material is synthesized in two-stage procedure. The first stage is galvanic silver electrodeposition on a glassy carbon substrate electrode. The second step is silver stripping followed by Aghcf formation during monomer oxidation. Deposited composite layer is compact but not homogenous in a micro-scale. The low spin iron centre redox activity depends on a kind of the electrolyte. Potassium and nitrate ions are the most suitable for redox couple reversibility. The redox activity diminishes in contact with electrolytes in series KNO3 > K2SO4 > KBr. In the presence of chloride ions redox activity of silver hexacyanoferrate is inhibited. Spectroelectrochemical measurements proved electrochromic character of the film.

Composites of tin oxide and different carbonaceous materials as negative electrodes in lithium-ion batteries

Tin and tin oxide have been considered as suitable materials with a high theoretical capacity for lithium ion batteries. Their low cost, high safety, and other technical benefits placed them as promising replacements for graphite negative electrodes. The problem to overcome with tin oxide, as well as with other metallic materials, is high volume changes during alloying/dealloying, subsequent pulverization, delamination from current collectors following continuous degradation of the anode. To solve these issues, different approaches have been applied. A number of various architectures from nanostructures to core-shell, porous, anchored, and encapsulated have been studied to improve cycling performance. Much attention was paid to incorporate carbonaceous materials. Here, summarized results regarding utilization of the tin oxide-carbonaceous negative electrode material are presented.