https://hdl.handle.net/10481/14202 2026-04-20T07:53:24Z https://hdl.handle.net/10481/98990 Band-like electron transport in 2D quantum dot periodic lattices: the effect of realistic size distributions Skibinsky Gitlin, Erik Sebastian; Rodríguez Bolívar, Salvador; Califano, Marco; Gómez Campos, Francisco Manuel Electron mobility in nanocrystal films has been a controversial topic in the last few years. Theoretical and experimental studies evidencing carrier transport by hopping or showing band-like features have been reported in the past. A relevant factor to analyze transport results is the progressive improvement in quantum dot superlattice fabrication, leading to better regimented structures for which band-like transport would be more relevant. This work presents an efficient model to compute temperature- dependent band-like electronic mobilities in 2D quantum dot arrays when a realistic quantum dot size distribution is considered. Comparisons with experimental results are used to estimate these size distributions, in good agreement with data of the samples. https://hdl.handle.net/10481/98987 Application of variable-order fractional calculus to the modeling of calendar aging in lithium-ion batteries López Villanueva, Juan Antonio; Rodríguez Iturriaga, Pablo; Parrilla Roure, Luis; Rodríguez Bolívar, Salvador Battery aging is one of the key challenges that electrochemical energy storage faces. Models for both cycling and calendar aging are valuable for quantitatively assessing their contribution to overall capacity loss. Since batteries are stored and employed under varying conditions of temperature and state of charge in their real-life operation, the availability of a suitable model to anticipate the outcome of calendar aging in lithium-ion batteries under dynamic conditions is of great interest. In this article, we extend a novel model to predict the capacity loss due to calendar aging by using variable-order fractional calculus. For this purpose, some theoretical difficulties posed by variable-order definitions are discussed and compared by applying them to fit experimental results with a multi-parameter optimization procedure. We show that employing a variable-order model allows for a significant improvement in accuracy and predictive ability with respect to its constant- order counterpart. We conclude that variable-order models constitute an interesting alternative for reproducing complex behavior in dynamical systems, such as aging in lithium-ion batteries https://hdl.handle.net/10481/98270 A novel Dual Fractional-Order Extended Kalman Filter for the improved estimation of battery state of charge Rodríguez Iturriaga, Pablo; Alonso-del-Valle, Jorge; Rodríguez Bolívar, Salvador; Anseán, David; Viera, Juan Carlos; López Villanueva, Juan Antonio Fractional-order models are gaining increasing relevance in battery modeling in light of the experimental measurements from Electrochemical Impedance Spectroscopy (EIS) tests, unequivocally indicating the presence of equivalent circuit components with an impedance of non-integer order. To attain their discrete state-space representation, the approach based on the Grünwald–Letnikov (GL) definition of the fractional derivative has been widely used, albeit its applicability beyond driving cycles remains open to discussion. In this article, we present a novel Dual Fractional-Order Extended Kalman Filter (DFOEKF) for the simultaneous estimation of State of Charge (SOC) and all fractional parameters, based on the multiple-RC approximation instead. We discuss the parameter identification of fractional-order elements on a NMC811/Si-Gr cell from both frequency and time-domain data, highlighting the importance of EIS measurements for the search of appropriate time-domain values. We validate the performance of this method experimentally at different operation stages, as well as its robustness to incorrect initializations, obtaining a SOC root-mean-square (RMS) error of 0.28% and a voltage RMS error of 15.2 mV in 20 complete charge–discharge cycles. The greatly accurate estimation results both within and outside the driving cycle stage make this method an interesting alternative for the fractional modeling of LIBs in online applications. https://hdl.handle.net/10481/98252 A method for the lifetime sensorless estimation of surface and core temperature in lithium-ion batteries via online updating of electrical parameters Rodríguez Iturriaga, Pablo; Anseán, David; López Villanueva, Juan Antonio; González, Manuela; Rodríguez Bolívar, Salvador Online temperature estimates are essential to the thermal monitoring and control of battery cells for battery management systems (BMSs). Due to hardware limitations, there has been a surge in interest in sensorless approaches for both surface and core temperatures. On this account, several methods have been proposed in the literature for the coestimation of state of charge (SOC) and temperature via RC-based electrical and thermal models and Extended Kalman Filters (EKFs). However, the stability and reliability of these schemes over the complete cell lifetime, when the effects of battery aging become apparent, have not been addressed thoroughly. In this article, a dual state-parameter estimation is carried out on an enhanced equivalent circuit model to coestimate the SOC and SOH on a commercial nickel-rich, silicon–graphite cell throughout its entire lifetime. A thermal model has been characterized based on the previous electrical model for the estimation of surface and core temperature of the cell. The continuous updating and correction of electrical parameters prove to be critical for temperature estimations to remain accurate in the long run, yielding a root mean square error (RMSE) in surface temperature below 1.2 °C for as long as 800 cycles.