Estudi de l'evolució de la capacitat de bescanvi catiònic durant el compostatge de diversos materials

Peer Reviewe

Dual extended Kalman filter for state of charge estimation of lithium–sulfur batteries

Lithium-Sulfur is a promising technology for the next generation of batteries and research efforts for early-stage prototype implementation increased in recent years. For the development of a suitable Battery Management System, a state estimator is required; however, lithium-sulfur behavior presents a large non-observable region that may difficult the convergence of the state estimation algorithm leading to large errors or even instability. A dual Extended Kalman Filter is proposed to circumvent the non-observability region. This objective is achieved by combining a parameter estimation algorithm with a cell model that includes non-linear behavior such as self-discharge and cell degradation. The resulting dual Kalman filter is applied to lithium–sulfur batteries to estimate their State-of-Charge incorporating the effects of degradation, temperature, and self-discharge deviations.Peer ReviewedObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No Contaminant::7.b - Per a 2030, ampliar la infraestructura i millorar la tecnologia per tal d’oferir serveis d’energia moderns i sos­tenibles per a tots els països en desenvolupament, en particular els països menys avançats, els petits estats insulars en desenvolupament i els països en desenvolupament sense litoral, d’acord amb els programes de suport respectiusObjectius de Desenvolupament Sostenible::7 - Energia Assequible i No ContaminantPostprint (published version

Automatització i programació dels fulls de càlcul

En la “Convocatòria d’ajuts per a projectes de millora de l’any 2003/2004” presentàvem el projecte “Temes de càlcul numèric amb el full de càlcul”. Amb aquell projecte proposàvem la utilització dels fulls de càlcul com a eina per a l’automatització dels processos numèrics implicats en els diferents temes que es poden impartir en un curs de Càlcul Numèric. La finalitat d’aquell projecte era la de fer un ús interactiu dels fulls de càlcul per a la resolució de problemes numèrics. El projecte que ara presentem persegueix anar més enllà de l’ús interactiu que es pot fer dels full de càlcul i explotar les capacitats que tenen per a ser programats. Els objectius a assolir son diversos: · Creació de fulls de càlcul de suport per a la docència. · Utilització dels fulls de càlcul com a potent eina de càlcul · Iniciar a l’alumne en el mon de l’algoritmia per tal d’adquirir destresa en els processos de modelització de solucions als problemes plantejats. · Introduir a l’alumne en el mon de l’algorítmia i la programació estructurada. · Iniciar a l’alumne en el llenguatge de programació “Visual Basic for Applications” (VBA), llenguatge de programació inclòs en el full de càlcul “Excel”

Tubular CoFeP@CN as a Mott–Schottky catalyst with multiple adsorption sites for robust lithium-sulfur batteries

The shuttle effect and the sluggish reaction kinetics of lithium polysulfide (LiPS) seriously compromise the performance of lithium–sulfur batteries (LSBs). To overcome these limitations and enable the fabrication of robust LSBs, here the use of a Mott–Schottky catalyst based on bimetallic phos- phide CoFeP nanocrystals supported on carbon nitride tubular nanostruc- tures as sulfur hosts is proposed. Theoretical calculations and experimental data confirm that CoFeP@CN composites are characterized by a suitable electronic structure and charge rearrangement that allows them to act as a Mott–Schottky catalyst to accelerate LiPS conversion. In addition, the tubular geometry of CoFeP@CN composites facilitates the diffusion of Li ions, accommodates volume change during the reaction, and offers abundant lithi- ophilic/sulfiphilic sites to effectively trap soluble LiPS. Therefore, S@CoFeP@ CN electrodes deliver a superior rate performance of 630 mAh g-1 at 5 C, and remarkable cycling stability with 90.44% capacity retention over 700 cycles. Coin cells with high sulfur loading, 4.1 mg cm-2, and pouch cells with 0.1 Ah capacities are further produced to validate their superior cycling stability. In addition, it is demonstrated here that CoFeP@CN hosts greatly alleviate the often overlooked issues of low energy efficiency and serious self-discharging in LSBs.Peer ReviewedPostprint (author's final draft

NbSe2 meets C2N: a 2D-2D heterostructure catalysts as multifunctional polysulfide mediator in ultra-long-life lithium–sulfur batteries

The shuttle effect and sluggish conversion kinetics of lithium polysulfides (LiPS) hamper the practical application of lithium–sulfur batteries (LSBs). Toward overcoming these limitations, herein an in situ grown C2N@NbSe2 heterostructure is presented with remarkable specific surface area, as a Li–S catalyst and LiPS absorber. Density functional theory (DFT) calculations and experimental results comprehensively demonstrate that C2N@NbSe2 is characterized by a suitable electronic structure and charge rearrangement that strongly accelerates the LiPS electrocatalytic conversion. In addition, heterostructured C2N@NbSe2 strongly interacts with LiPS species, confining them at the cathode. As a result, LSBs cathodes based on C2N@NbSe2/S exhibit a high initial capacity of 1545 mAh g-1 at 0.1 C. Even more excitingly, C2N@NbSe2/S cathodes are characterized by impressive cycling stability with only 0.012% capacity decay per cycle after 2000 cycles at 3 C. Even at a sulfur loading of 5.6 mg cm-2, a high areal capacity of 5.65 mAh cm-2 is delivered. These results demonstrate that C2N@NbSe2 heterostructures can act as multifunctional polysulfide mediators to chemically adsorb LiPS, accelerate Li-ion diffusion, chemically catalyze LiPS conversion, and lower the energy barrier for Li2S precipitation/decomposition, realizing the “adsorption-diffusion-conversion” of polysulfides.Award-winningPostprint (author's final draft

Atomically dispersed Fe in a C2N based catalyst as a sulfur host for efficient lithium–sulfur batteries

Lithium–sulfur batteries (LSBs) are considered to be one of the most promising next generation energy storage systems due to their high energy density and low material cost. However, there are still some challenges for the commercialization of LSBs, such as the sluggish redox reaction kinetics and the shuttle effect of lithium polysulfides (LiPS). Here a 2D layered organic material, C2N, loaded with atomically dispersed iron as an effective sulfur host in LSBs is reported. X-ray absorption fine spectroscopy and density functional theory calculations prove the structure of the atomically dispersed Fe/C2N catalyst. As a result, Fe/C2N-based cathodes demonstrate significantly improved rate performance and long-term cycling stability. Fe/C2N-based cathodes display initial capacities up to 1540 mAh g-1 at 0.1 C and 678.7 mAh g-1 at 5 C, while retaining 496.5 mAh g-1 after 2600 cycles at 3 C with a decay rate as low as 0.013% per cycle. Even at a high sulfur loading of 3 mg cm-2, they deliver remarkable specific capacity retention of 587 mAh g-1 after 500 cycles at 1 C. This work provides a rational structural design strategy for the development of high-performance cathodes based on atomically dispersed catalysts for LSBs.Peer ReviewedPostprint (author's final draft

Tubular CoFeP@CN as a Mott–Schottky Catalyst with Multiple Adsorption Sites for Robust Lithium−Sulfur Batteries

The shuttle effect and the sluggish reaction kinetics of lithium polysulfide (LiPS) seriously compromise the performance of lithium–sulfur batteries (LSBs). To overcome these limitations and enable the fabrication of robust LSBs, here the use of a Mott–Schottky catalyst based on bimetallic phosphide CoFeP nanocrystals supported on carbon nitride tubular nanostructures as sulfur hosts is proposed. Theoretical calculations and experimental data confirm that CoFeP@CN composites are characterized by a suitable electronic structure and charge rearrangement that allows them to act as a Mott–Schottky catalyst to accelerate LiPS conversion. In addition, the tubular geometry of CoFeP@CN composites facilitates the diffusion of Li ions, accommodates volume change during the reaction, and offers abundant lithiophilic/sulfiphilic sites to effectively trap soluble LiPS. Therefore, S@CoFeP@CN electrodes deliver a superior rate performance of 630 mAh g at 5 C, and remarkable cycling stability with 90.44% capacity retention over 700 cycles. Coin cells with high sulfur loading, 4.1 mg cm, and pouch cells with 0.1 Ah capacities are further produced to validate their superior cycling stability. In addition, it is demonstrated here that CoFeP@CN hosts greatly alleviate the often overlooked issues of low energy efficiency and serious self-discharging in LSBs.This work was supported by the European Regional Development Funds and by the Spanish Ministerio de Economía y Competitividad through the project ENE2016-77798-C4-3-R, and ENE2017-85087-C3. C.Q.Z., R.F.D., K.X., D.W.Y., T.Z., and X.W. thank the China Scholarship Council for the scholarship support. The authors acknowledge funding from Generalitat de Catalunya 2017 SGR 327 and 2017 SGR 1246. ICN2 acknowledges the support from the Severo Ochoa Programme (MINECO, grant no. SEV-2017-0706) and was funded by the CERCA Programme/Generalitat de Catalunya. J.L. is a Serra Húnter Fellow and is grateful to MICINN/FEDER RTI2018-093996-B-C31, GC 2017 SGR 128 and to ICREA Academia program

Exploring the nanoscale origin of performance enhancement in Li1.1_{1.1}Ni0.35_{0.35}Mn0.55_{0.55}O2_2 batteries due to chemical doping

Despite significant potential as energy storage materials for electric vehicles due to their combination of high energy density per unit cost and reduced environmental and ethical concerns, Co-free lithium ion batteries based off layered Mn oxides presently lack the longevity and stability of their Co-containing counterparts. Here, we demonstrate a reduction in this performance gap via chemical doping, with Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$ achieving an initial discharge capacity of 159 mAhg$^{-1}$ at C/3 rate and a corresponding capacity retention of 94.3% after 150 cycles. We subsequently explore the nanoscale origins of this improvement through a combination of advanced diffraction, spectroscopy, and electron microscopy techniques, finding that optimized doping profiles lead to an improved structural and chemical compatibility between the two constituent sub-phases that characterize the layered Mn oxide system, resulting in the formation of unobstructed lithium ion pathways between them. We also directly observe a structural stabilization effect of the host compound near the surface using aberration corrected scanning transmission electron microscopy and integrated differential phase contrast imaging.Comment: 20 pages, 8 figure

“Muntanyes i refugis”: investigadors de l’IBB publiquen un estudi genètic sobre endemismes de les muntanyes de Grècia

Noticia publicada en la web institucional del Instituto Botánico de Barcelona el 5 de noviembre de 2015 -- Disponibles PDFs en español y catalán y capturas de pantalla de la noticia en la web.Peer reviewe

Speciation and genetic diversity in Centaurea subsect. Phalolepis in Anatolia

14 p., mapas, tablasMountains of Anatolia are one of the main Mediterranean biodiversity hotspots and their richness in endemic species amounts for 30% of the flora. Two main factors may account for this high diversity: the complex orography and its role as refugia during past glaciations. We have investigated seven narrow endemics of Centaurea subsection Phalolepis from Anatolia by means of microsatellites and ecological niche modelling (ENM), in order to analyse genetic polymorphisms and getting insights into their speciation. Despite being narrow endemics, all the studied species show moderate to high SSR genetic diversity. Populations are genetically isolated, but exchange of genes probably occurred at glacial maxima (likely through the Anatolian mountain arches as suggested by the ENM). The lack of correlation between genetic clusters and (morpho) species is interpreted as a result of allopatric diversification on the basis of a shared gene pool. As suggested in a former study in Greece, post-glacial isolation in mountains would be the main driver of diversification in these plants; mountains of Anatolia would have acted as plant refugia, allowing the maintenance of high genetic diversity. Ancient gene flow between taxa that became sympatric during glaciations may also have contributed to the high levels of genetic diversity.This work was supported by the Spanish Ministerio de Ciencia e Innovación [project CGL2010/18631] and Generalitat de Catalunya [Ajuts a Grups de Recerca Consolidats 2014-SGR514-GREB]Peer reviewe