Optimization of sulphur content in LiMn2O4−ySyLiMn_2O_{4-y}S_y spinels as cathode materials for lithium-ion batteries

Sulphur doped lithium manganese spinels with a nominal composition of LiMn2O4-ySy (0≤y≤0.02) were synthesized by a modified sol-gel method followed by calcinations at 300 and 650 °C in air. The prepared materials were characterized in terms of physicochemical properties using X-ray powder diffraction (XRD), differential scanning calorimetry (DSC) and electrical conductivity studies (EC). Electrochemical characteristic of Li/Li+/LiMn2O4-ySy cells was examined by galvanostatic charge/discharge tests (CELL TEST), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). It was shown that small amount of sulphur in LiMn2O4 spinel enhances the structural integrity of the host material and increases the electrochemical performance

Novel method of preparation of C/Sn−SnO2C/Sn-SnO_2 nanocomposite Li-ion anode material derived from plant polysaccharides

C/Sn - SnO 2 nanocomposite was obtained in one step pyrolysis and carbore duction process, providing formation of tin - based nanograins encapsulated in carbon buffer matrix derived from plan t polysaccharide (potato starch). Electrical conductivity of t he obtained material was carried out within temperature range - 20÷ 40 ̊ C. Cyclic voltammetry (CV) and charge - discharge tests were pe rformed in Li/Li + /(C/Sn - SnO 2 ) R2032 - type coin cells within 0.02 ÷ 1 .5 V potential range. Furthermore , electrochemical impedance spectroscopy (EIS) was used to characterize electrochemica l properties of the nanocomposite. The C/Sn - SnO 2 anode material provided at least 538 mAh g -1 at C/20 – rate and revealed good coulombic efficiency and capacity retention in charge - discharge cell tests

A strategy to optimize the performance of bio-derived carbon aerogels by a structuring additive

In this work, we investigated the influence of gum arabic (GA) as a structuring additive, on the electrochemical behavior of bio-derived carbon aerogels (CAGs). Modified carbonaceous materials were prepared by the gelatinization process of potato starch (PS) with the addition of GA in various quantities, followed by the thermal treatment of the obtained gels in an inert gas atmosphere. The obtained anode materials were examined by X-ray diffraction (XRD), elemental analysis (EA), galvanostatic charge/discharge tests (GCDT), extensive cycling (LT-GCDT) and cyclic voltammetry (CV) methods. The highest electrochemical performance was achieved for carbon aerogel material, in which 1% w/w GA was added. The results showed that the proper composition of carbon precursor with a structuring promoter improves the rheological properties of starch gel and stabilizes the final aerogel structure affecting CAG functional properties

Nitrogen-doped carbon aerogels derived from starch biomass with improved electrochemical properties for Li-ion batteries

Among all advanced anode materials, graphite is regarded as leading and still-unrivaled. However, in the modern world, graphite-based anodes cannot fully satisfy the customers because of its insufficient value of specific capacity. Other limitations are being nonrenewable, restricted natural graphite resources, or harsh conditions required for artificial graphite production. All things considered, many efforts have been made in the investigation of novel carbonaceous materials with desired properties produced from natural, renewable resources via facile, low-cost, and environmentally friendly methods. In this work, we obtained N-doped, starch-based carbon aerogels using melamine and N(2) pyrolysis as the source of nitrogen. The materials were characterized by X-ray powder diffraction, elemental analysis, X-ray photoelectron spectroscopy, galvanostatic charge–discharge tests, cyclic voltammetry, and electrochemical impedance spectroscopy. Depending on the doping method and the nitrogen amount, synthesized samples achieved different electrochemical behavior. N-doped, bioderived carbons exhibit far better electrochemical properties in comparison with pristine ones. Materials with the optimal amount of nitrogen (such as MCAGPS-N8.0%—carbon aerogel made from potato starch modified with melamine and CAGPS-N1.2%—carbon aerogel made from potato starch modified by N(2) pyrolysis) are also competitive to graphite, especially for high-performance battery applications. N-doping can enhance the efficiency of Li-ion cells mostly by inducing more defects in the carbon matrix, improving the binding ability of Li(+) and charge-transfer process

Electrochemical properties and structure evolution of starch-based carbon nanomaterials as Li-ion anodes with regard to thermal treatment

The influence of the pyrolysis temperature on the structural, textural, and electrochemical properties of carbon aerogels obtained from potato, maize, and rice starches was analyzed. The carbonization of organic precursors, followed by gelatinization, exchange of solvent, and drying process, was carried out in an argon atmosphere at temperatures ranging from 600 °C to 1600 °C. The nanostructured carbons were characterized by X-ray powder diffraction (XRD) as well as N2-adsorption/desorption (N2-BET) methods. The electrochemical behavior of Li-ion cells based on the fabricated carbon anodes was investigated using the galvanostatic charge/discharge tests (GCDT) and electrochemical impedance spectroscopy (EIS). The results show that the thermal treatment stage has a crucial impact on the proper formation of the aerogel material’s porous structures and also on their working parameters as anode materials. The highest relative development of the external surface was obtained for the samples pyrolysed at 700 °C, which exhibited the best electrochemical characteristics (the highest specific capacities as well as the lowest charge transfer resistances)

Multifunctional carbon aerogels derived by sol–gel process of natural polysaccharides of different botanical origin

In this manuscript, we describe the results of our recent studies on carbon aerogels derived from natural starches. A facile method for the fabrication of carbon aerogels is presented. Moreover, the complete analysis of the carbonization process of different starch aerogels (potato, maize, and rice) was performed using thermogravimetric studies combined with a detailed analysis of evolved decomposition products. The prepared carbon aerogels were studied in terms of their morphology and electrical properties to relate the origin of starch precursor with final properties of carbon materials. The obtained results confirmed the differences in carbon aerogels’ morphology, especially in materials’ specific surface areas, depending on the botanical origin of precursors. The electrical conductivity measurements suggest that carbon aerogels with the best electrical properties can be obtained from potato starch

Materiały katodowe dla nowej generacji akumulatorów typu Li-ion

Od wielu lat kwestia uzyskania możliwie taniej energii do celów przemysło- wych i konsumpcyjnych nabiera coraz większej wagi. Wyczerpywanie się zaso- bów nieodnawialnych, jak również wymagania prawne w zakresie ochrony śro- dowiska zmuszają kraje o wysokim poziomie rozwoju gospodarczego do dywer- syfikacji źródeł wytwarzania i gromadzenia energii. Wśród szeregu urządzeń i układów do magazynowania energii, ze względu na obiecujące parametry użyt- kowe, do których należą: duża gęstość energii, wysokie napięcie pracy, niski współczynnik samorozładowania, dobra trwałość cykliczna oraz szeroki zakres temperatur pracy, na uwagę zasługują akumulatory Li-Ion. Obecnie jednym z największych wyzwań w konstrukcji systemów litowo-jonowych jest znale- zienie nowych rozwiązań materiałowych, które doprowadzą do zmniejszenia kosztów, poprawy parametrów pracy oraz bezpieczeństwa użytkowania ogniw

Synthesis and characteristic of C/Sn anode nanocomposites for high capacity lithium batteries

Gwałtowny rozwój techniki oraz wzrost zapotrzebowania na energię elektryczną przyczyniły się do opracowania bardziej wydajnych i jednocześnie niezawodnych źródeł magazynowania energii. Obecnie szczególną pozycję na rynku zajmują akumulatory litowe, które cechują się dużą gęstością magazynowanej energii, wysokim napięciem pracy oraz dobrą trwałością cykliczną. W powszechnie dostępnych odwracalnych ogniwach litowych, jako materiał anodowy stosowany jest głównie grafit. Wciąż jednak poszukuje się nowych aktywnych materiałów elektrodowych, które sprostałyby coraz to większym wymaganiom przemysłu elektronicznego i motoryzacyjnego. Obiecującym materiałem anodowym jest cyna. Jej pojemność teoretyczna (994 mAh/g) jest 2,5-krotnie większa od pojemności grafitu (372 mAh/g). Cyna wykazuje jednak znaczny wzrost objętości (do 300%) zachodzący podczas interkalacji jonów litu. W konsekwencji, w ogniwie pojawiają się ogromne naprężenia, które mogą prowadzić do jego zniszczenia. W celu rozwiązania tego problemu proponuje się utworzenie nanokompozytów C/Sn, w których amorficzny węgiel będzie stanowił matrycę zdolną do amortyzowania dużych zmian objętości nanocząstek cyny.Celem niniejszej pracy była synteza i charakterystyka nanokompozytów C/Sn. Nanoproszki tlenku cyny(IV) zsyntezowano metodą odwróconej mikroemulsji, używając dwóch różnych czynników strącających: węglanu amonu i amoniaku. Następnie otrzymany materiał pokryto substancją polimerową, stanowiącą źródło węgla. Tak utworzone prekursory kompozytów poddano pirolizie. Optymalne warunki preparatyki określono stosując metody analizy termicznej (EGA-TGA/DTG/SDTA). Analizę strukturalną badanych materiałów wykonano metodą rentgenowskiej dyfrakcji proszkowej (XRD). Morfologię powierzchni określono zaś w oparciu o metodę izotermy BET. Dodatkowe informacje dotyczące struktury i morfologii kompozytów uzyskano z transmisyjnej mikroskopii elektronowej (TEM). Pomiar właściwości elektrycznych (EC) przeprowadzono w warunkach prądu zmiennego.The growing demand of high capacity lithium batteries for portable electronics and electric vehicles creates a need for new and improved electrode materials. Commercial Li-Ion batteries employ graphite as the anode, as it complies with safety and stability issue. The capacity corresponding to the formation of LiC6 is 372 mAh/g. Significantly higher capacities can be achieved by using tin (Li22Sn5; 994 mAh/g). This metal alloy is promising anode material due to its lithium uptake at low potential and high theoretical capacity. However, the major problem related to this material is the cycling instability caused by the extremely large volume changes (up to 300%) during lithium intercalation. One possibility to solve this issue is formation of nanocomposites consisting of core/shell nanoparticles with an active core (tin) and a stabilizing shell (carbon). Such materials could benefit from their nanoporous morphology featuring local free space to compensate volume changes. The purpose of the present work, was to synthesize and characterize C/Sn nanocomposites. Tin dioxide nanopowders were synthesized using the reverse microemulsion technique. Then, the SnO2 grains were impregnated with polymers composition in water solution. To obtain C/Sn composites, the polymer/SnO2 composite precursors were pyrolysed. The detailed condition for preparation process was studied using thermal analysis method (EGA-TGA/DTG/SDTA). The structure and the morphology of the samples were characterized by XRD and BET analysis as well as visualized by transmission electron microscopy (TEM). The electrical properties of C/Sn composites were determined by ac 4-probe method