Browsing by Autor "Anders Lundblad"

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Crystal structure and Hirshfeld surface analysis of poly[tris(μ4-benzene-1,4-dicarboxylato)tetrakis(dimethylformamide)trinickel(II)]: a two-dimensional coordination network
(International Union of Crystallography, 2019) Cesario Ajpi; Leopoldo Suescun; Naviana Leiva; Anders Lundblad; Göran Lindbergh; Saúl Cabrera
The crystal structure of the title compound, [Ni3(C8H4O4)3(C3H7NO)4], is a two-dimensional coordination network formed by trinuclear linear Ni3(tp)3(DMF)4 units (tp = terephthalate = benzene-1,4-di-carboxyl-ate and DMF = di-methyl-formamide) displaying a characteristic coordination mode of acetate groups in polynuclear metal-organic compounds. Individual trinuclear units are connected through tp anions in a triangular network that forms layers. One of the DMF ligands points outwards and provides inter-actions with equivalent planes above and below, leaving the second ligand in a structural void much larger than the DMF mol-ecule, which shows positional disorder. Parallel planes are connected mainly through weak C-H⋯O, H⋯H and H⋯C inter-actions between DMF mol-ecules, as shown by Hirshfeld surface analysis.
Effect of Partial Cycling of NCA/Graphite Cylindrical Cells in Different SOC Intervals
(Institute of Physics, 2020) Fabian Andres Benavente; Maria Varini; Anders Lundblad; Saúl Cabrera; Göran Lindbergh
A quasi-realistic aging test of NCA/graphite lithium-ion 18650 cylindrical cells is performed during a long-term low c-rate cycling and using a new protocol for testing and studying the aging. This to emulate a characteristic charge/discharge profile of off-grid PV-battery systems. The cells were partially cycled at four different cut-off voltages and two state of charge ranges (ΔSOC) for 1000 and 700 cycles over 24 months. Differential voltage analysis shows that a combination of loss of active material (LAM) and loss of lithium inventory (LLI) are the causes of capacity loss. Cells cycled with high cut-off voltages and wide ΔSOC (20% to 95%) were severely affected by material degradation and electrode shift. High cut-off voltage and narrow ΔSOC (65% to 95%) caused greater electrode degradation but negligible cell unbalance. Cell impedance is observed to increase in both cells. Cells cycled with middle to low cut-off voltages and narrow ΔSOC (35%–65% and 20% to 50%) had comparable degradation rates to calendar-aged cells. Cycling NCA/graphite cells with low c-rate and high cut-off voltages will degrade the electrode in the same way high c-rate would do. However, low c-rate at low and middle cut-off voltages greatly decrease cell degradation compared to similar conditions at middle to high c-rate, therefore increasing battery lifetime.
Electrochemical Evaluation of the Aging Process for NCA/Graphite Cylindrical Cells Intended for Off-Grid PV Applications
(Institute of Physics, 2018) Fabian Andres Benavente; Anders Lundblad; Saúl Cabrera; Maria Varini; Göran Lindbergh
The aging of lithium ion batteries in off-grid photovoltaic (PV) energy systems is evaluated. Off-grid PV systems can improve their reliability and efficiency by storing the excess of energy produced during sunny days and using it when no other source of energy is available. Due to its high energy density, high efficiency, and constantly drop in prices, lithium ion batteries are the most suitable option to be integrated in the system as energy storage [1]. Although the impressive features, lithium ion batteries properties need to be studied further in order to achieve more efficient renewable energy systems [2]. One of the determinant property to be evaluated is the lifetime of the lithium ion battery, which is determined by aging factors [3]. In this work we have studied the capacity fade and impedance increase as aging factors. State of charge (SOC) profiles corresponding to most common applications found in off-grid PV-systems were used to cycle NCA/graphite cylindrical for 8 months in the laboratory. Four SOC ranges were used to cycle the cells; Low ΔSOC (20% to 50%), middle ΔSOC (35% to 65%), high ΔSOC (65% to 95%), and and full ΔSOC (20% to 95%). Electrochemical techniques were used to characterize both capacity fade and impedance increase in full cells. Discharge at C/25 rate was performed to measure the capacity every 100 cycles. Impedance increase due to the solid electrolyte interface (SEI) formation and other unwanted process was determined by performing electrochemical impedance spectroscopy (EIS) measurements along with hybrid power pulse characterization techniques. Half cells and symmetrical cells were built to identify aging process on the NCA and graphite electrodes independently with the same electrochemical techniques described above. From Figure 1- a) we can observe a relatively large capacity fade of the C/25 discharge capacity on cells cycled at high ΔSOC, and almost similar behavior was observed in cells cycled at full ΔSOC. Whereas, for cells cycled at low ΔSOC and middle ΔSOC the capacity fade is small in comparison. Comparison between dV/dQ curves show a shifting and growing of peaks as the number of cycles increase. These changes are more evident in cells cycled at high ΔSOC and full ΔSOC, Figure 1- b) . The EIS measurements show a relatively large increase of impedance in the Nyquist plot for the cells cycled at high ΔSOC and full ΔSOC, along with a formation of a second semicircle at the mid frequency range, which is also observed for cells cycled at low ΔSOC and middle ΔSOC, Figure 1- c) . Bibliography [1] D. Parra and M. K. Patel, “Effect of tariffs on the performance and economic benefits of PV-coupled battery systems,” Appl. Energy , vol. 164, pp. 175–187, 2016. [2] Y. Zhang, A. Lundblad, P. E. Campana, F. Benavente, and J. Yan, “Battery sizing and rule-based operation of grid-connected photovoltaic-battery system: A case study in Sweden,” Energy Convers. Manag. , vol. 133, pp. 249–263, 2017. [3] M. Klett, R. Eriksson, J. Groot, P. Svens, K. Ciosek Högström, R. W. Lindström, H. Berg, T. Gustafson, G. Lindbergh, and K. Edström, “Non-uniform aging of cycled commercial LiFePO4//graphite cylindrical cells revealed by post-mortem analysis,” J. Power Sources , vol. 257, pp. 126–137, 2014. Figure 1
Loss-of-load probability analysis for optimization of small off-grid PV-battery systems in Bolivia
(Elsevier BV, 2017) Fabian Andres Benavente; Anders Lundblad; Pietro Elia Campana; Yang Zhang; Saúl Cabrera; Göran Lindbergh
Photovoltaic/battery system sizing for rural electrification in Bolivia: Considering the suppressed demand effect
(Elsevier BV, 2018) Fabian Andres Benavente; Anders Lundblad; Pietro Elia Campana; Yang Zhang; Saúl Cabrera; Göran Lindbergh
Rural electrification programs usually do not consider the impact that the increment of demand has on the reliability of off-grid photovoltaic (PV)/battery systems. Based on meteorological data and electricity consumption profiles from the highlands of Bolivian Altiplano, this paper presents a modelling and simulation framework for analysing the performance and reliability of such systems. Reliability, as loss of power supply probability (LPSP), and cost were calculated using simulated PV power output and battery state of charge profiles. The effect of increasing the suppressed demand (SD) by 20% and 50% was studied to determine how reliable and resilient the system designs are. Simulations were performed for three rural application scenarios: a household, a school, and a health centre. Results for the household and school scenarios indicate that, to overcome the SD effect, it is more cost-effective to increase the PV power rather than to increase the battery capacity. However, with an increased PV-size, the battery ageing rate would be higher since the cycles are performed at high state of charge (SOC). For the health centre application, on the other hand, an increase in battery capacity prevents the risk of electricity blackouts while increasing the energy reliability of the system. These results provide important insights for the application design of off-grid PV-battery systems in rural electrification projects, enabling a more efficient and reliable source of electricity.
Synthesis and Characterization of LiFePO4–PANI Hybrid Material as Cathode for Lithium-Ion Batteries
(Multidisciplinary Digital Publishing Institute, 2020) Cesario Ajpi; Naviana Leiva; Max Vargas; Anders Lundblad; Göran Lindbergh; Saúl Cabrera
This work focuses on the synthesis of LiFePO4-PANI hybrid materials and studies their electrochemical properties (capacity, cyclability and rate capability) for use in lithium ion batteries. PANI synthesis and optimization was carried out by chemical oxidation (self-assembly process), using ammonium persulfate (APS) and H3PO4, obtaining a material with a high degree of crystallinity. For the synthesis of the LiFePO4-PANI hybrid, a thermal treatment of LiFePO4 particles was carried out in a furnace with polyaniline (PANI) and lithium acetate (AcOLi)-coated particles, using Ar/H2 atmosphere. The pristine and synthetized powders were characterized by XRD, SEM, IR and TGA. The electrochemical characterizations were carried out by using CV, EIS and galvanostatic methods, obtaining a capacity of 95 mAhg-1 for PANI, 120 mAhg-1 for LiFePO4 and 145 mAhg-1 for LiFePO4-PANI, at a charge/discharge rate of 0.1 C. At a charge/discharge rate of 2 C, the capacities were 70 mAhg-1 for LiFePO4 and 100 mAhg-1 for LiFePO4-PANI, showing that the PANI also had a favorable effect on the rate capability.
Synthesis and spectroscopic characterization of Fe3+-BDC metal organic framework as material for lithium ion batteries
(Elsevier BV, 2022) Cesario Ajpi; Naviana Leiva; Anders Lundblad; Göran Lindbergh; Saúl Cabrera
Synthesis and spectroscopic characterization of NiII coordination network: Poly-[tris(µ4-Benzene-1,4-dicarboxylato)-tetrakis(µ1-dimethylformamide-κ1O)-trinickel(II)] as material for lithium ion batteries
(Elsevier BV, 2022) Cesario Ajpi; Naviana Leiva; Max Vargas; Anders Lundblad; Göran Lindbergh; Saúl Cabrera
The compound Ni3(C8H4O4)3(C3H7NO)3, poly-[tris(µ4-Benzene-1,4-dicarboxylato)-tetrakis(µ1-dimethylformamide-κ1O)-trinickel(II)], was synthesized by the solvothermal method prepared via reaction between NiCl2•6H2O and terephthalic acid using N,N-dimethylformamide (DMF) as solvent. The structure was characterized by powder X-ray diffraction and infrared spectroscopy analyses. The electrochemical properties as a potential active material in lithium-ion batteries were characterized by electrochemical impedance spectroscopy and galvanostatic charge-discharge curves in a battery half-cell. The characterization results show that the coordination network contains one independent structure in the asymmetric unit. It is constructed from Ni2+ ions, terephthalate bridges and in-situ-generated DMF ligands, forming two similar two-dimensional (2D) layer structures. These similar 2D layers are in an alternating arrangement and are linked with each other by dense H—H interactions (45%) to generate a three-dimensional (3D) supramolecular framework with ordered and disordered DMF molecules. The electrochemical measurements, conducted in the potential range of 0.5–3.5 V vs Li/Li+, show that Ni3(C8H4O4)3(C3H7NO)4 has good electrochemical properties and can work as anode in lithium-ion batteries. The material presents an initial specific capacity of ∼420 mAh g−1, which drops during consecutive scans but stabilizes at ∼50 mAh g−1. However, due to the wide potential range there are indications of a gradual collapse of the structure. The electrochemical impedance spectroscopy shows an increase of charge transfer resistance from 24 to 1190 Ohms after cycling likely due to this collapse.