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  • 1.
    Bessman, Alexander
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Soares, Rúdi
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Wallmark, Oskar
    KTH, School of Electrical Engineering and Computer Science (EECS), Electric Power and Energy Systems.
    Svens, Pontus
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Aging effects of AC harmonics on lithium-ion cells2019In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 21, p. 741-749Article in journal (Refereed)
    Abstract [en]

    With the vehicle industry poised to take the step into the era of electric vehicles, concerns have been raised that AC harmonics arising from switching of power electronics and harmonics in electric machinery may damage the battery. In light of this, we have studied the effect of several different frequencies on the aging of 28 Ah commercial NMC/graphite prismatic lithium-ion battery cells. The tested frequencies are 1 Hz, 100 Hz, and 1 kHz, all with a peak amplitude of 21 A. Both the effect on cycled cells and calendar aged cells is tested. The cycled cells are cycled at a rate of 1C:1C, i.e., 28 A during both charging and discharging, with the exception of a period of constant voltage at the end of every charge. After running for one year, the cycled cells have completed approximately 2000 cycles. The cells are characterized periodically to follow how their capacities and power capabilities evolve. After completion of the test about 80% of the initial capacity remained and no increase in resistance was observed. No negative effect on either capacity fade or power fade is observed in this study, and no difference in aging mechanism is detected when using non-invasive electrochemical methods of post mortem investigation.

  • 2.
    Khan, Mohammad
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Zhao, Nan
    KTH, School of Engineering Sciences (SCI), Physics, Nuclear Power Safety.
    Xu, Tianhao
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Applied Thermodynamics and Refrigeration.
    Assessment of PECM as an efficient numerical analysis tool for investigating convective heat transfer phenomena during PCM melting2019In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 24, article id 100743Article in journal (Refereed)
    Abstract [en]

    In the framework of this research work, the principle focus is to assess the applicability & reliability of the Phase change Effective Convectivity Model (PECM) as a numerical analysis tool to investigate natural convective heat transfer in single and two-fluid density PCM molten pools. The model is applied in ANSYS FLUENT as User Defined Function (UDF) to predict convective melt pool thermal hydraulics in a volumetrically heated PCM (Phase Change Material) melt pool. As a part of this work, PECM is tested first by a benchmark case against CFD to gain confidence in its applicability as an analysis tool. Two commercial PCMs: RT50 and C58, are introduced in a 3D semicircular vessel slice with their thermo-physical properties as input for modelling. The sidewalls made of quartz glass are used for direct visualization of convective heat transfer phenomena. It is ensured that the conditions of nearly constant density of power deposition over the entire volume of the PCM melt pool throughout the series of simulation cases. The values of characteristic numbers ranged within the following limits with different pool height corresponding modified Rayleigh number Ra=1012-1013 and for Prandtl number Pr=5-7. The selected modelling approach is validated against SIGMA experiment with respect to the angular distribution of heat flux that qualify our model to run in the proceeding calculation using PECM. Following benchmark test results of PECM compared with that of conventional enthalpy porosity method embedded in ANSYS FLUENT, PECM is applied in 1-layer and 2-layer PCM configuration to study in details of the influence of different boundary conditions, internal heat sources (QV) and heat transfer fluid (HTF) cooling condition to quantify the thermal loads. Finally, the comparison is made between two PCM configurations in terms of the quantification of the thermal load to justify PECM as an efficient numerical analysis tool for investigating convective heat transfer phenomena during PCM melting.

  • 3.
    Lorenzi, Guido
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology. IN+, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
    da Silva Vieira, Ricardo
    MARETEC/LARSYS, Environment and Energy, Scientific Area, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
    Santos Silva, Carlos Augusto
    IN+, Instituto Superior Técnico, Universidade de Lisboa, Lisbon, Portugal.
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic analysis of utility-scale energy storage in island settingsIn: Journal of Energy Storage, E-ISSN 2352-152XArticle in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The decarbonization of the electricity supply in isolated and remote energy systems is an open challenge in the transition to a sustainable energy system. In this paper, the possibility to increase the penetration of renewable energy sources for electricity generationon the island of Terceira (Azores) is investigated through the installation of a utility-scale energy storage facility. The electric power dispatch on the island is simulated through a unit commitment model of the fossil and renewable power plants that has the objective of minimizing the cost of electricity generation. Battery energy storage is employed to partially decouple production and supply, and to provide spinning reserve in case of sudden generator outage. Two technological options, namely lithium-ion and vanadium flow batteries, are compared in terms of net present value and return on investment, with the aim of supporting the decision-making process of the local utility. The economic evaluation takes also into account the degradation of the battery performance along the years. The results, obtained in a future-price scenario, show that both the technologies entail a positive investment performance. However, vanadium flow batteries have the best results, given that they produce a net present value of up to 242% of the initial capital invested after 20 years, with a return on investment higher than 20%. In this scenario, the renewable share can reachup to 46%, compared to the current 26%.

  • 4.
    Lorenzi, Guido
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Vieira, Ricardo da Silva
    Univ Lisbon, Inst Super Tecn, Environm & Energy Sci Area, MARETEC LARSYS, Ave Rovisco Pais 1, P-1049001 Lisbon, Portugal..
    Santos Silva, Carlos Augusto
    Univ Lisbon, Inst Super Tecn, IN, Ave Rovisco Pais 1, P-1049001 Lisbon, Portugal..
    Martin, Andrew R.
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology.
    Techno-economic analysis of utility-scale energy storage in island settings2019In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 21, p. 691-705Article in journal (Refereed)
    Abstract [en]

    The decarbonization of the electricity supply in isolated and remote energy systems is an open challenge in the transition to a sustainable energy system. In this paper, the possibility to increase the penetration of renewable energy sources for electricity generation on the island of Terceira (Azores) is investigated through the installation of a utility-scale energy storage facility. The electric power dispatch on the island is simulated through a unit commitment model of the fossil and renewable power plants that has the objective of minimizing the cost of electricity generation. Battery energy storage is employed to partially decouple production and supply, and to provide spinning reserve in case of sudden generator outage. Two technological options, namely lithium-ion and vanadium flow batteries, are compared in terms of net present value and return on investment, with the aim of supporting the decision-making process of the local utility. The economic evaluation takes also into account the degradation of the battery performance along the years. The results, obtained in a future-price scenario, show that both the technologies entail a positive investment performance. However, vanadium flow batteries have the best results, given that they can produce a net present value that exceeds 430% of the initial capital invested after 20 years, with a return on investment higher than 35%. In this scenario, the renewable share can reach up to 46%, compared to the current 26%.

  • 5.
    Mussa, Abdilbari
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Klett, Matilda
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry. Scania CV AB, SE-151 87 Södertälje, Sweden.
    Gudmundson, Peter
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.).
    Svens, P.
    Lindström, Rakel
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Inhomogeneous active layer contact loss in a cycled prismatic lithium-ion cell caused by the jelly-roll curvature2018In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 20, p. 213-217Article in journal (Refereed)
    Abstract [en]

    Internal resistance is a key parameter that affects the power, energy, efficiency, lifetime, and safety of a lithium-ion battery. It grows due to chemical and mechanical battery wear during ageing. In this work, the effect of the jelly-roll winding curvature on impedance rise is investigated. NMC electrode samples, harvested from the curved as well as the flat regions of the jelly-roll from cycle-aged and calendar-aged prismatic cells (25 Ah, hard casing) are investigated by electrochemical impedance spectroscopy. After cycling, larger impedance rise is observed at the outer radius (concave) of the curved region compared to the inner radius (convex) or the flat region of the jelly-roll, and the difference increases with a decrease in the jelly-roll radius of curvature, from the cell skin towards the core. To identify the causes behind the observed difference in the impedance rise, investigations at different external compression (0 and 2.5 MPa) and temperature (5 and 25 °C) are performed. The results show that contact loss between the current collector and the active layer is the main source of the difference in impedance rise. Mechanical mechanisms that may cause the contact loss are discussed and design recommendations to mitigate the rise in impedance are given. 

  • 6.
    Pham, Cong-Toan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Månsson, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Assessment of energy storage systems for power system applications via suitability index approach (Part IV)2019In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 24, article id 100777Article in journal (Refereed)
    Abstract [en]

    Energy storage systems provide several benefits and services in optimizing the power grid's reliability, efficiencyand safety. However, the feasibility of energy storage systems varies dependent on the requirements of theapplications. Technical limitations in design and type of the storage technology prevents a single storage type toperform equally well in all situations. Hence, it is essential to compare and measure the energy storages’ usefulnessand determine their optimal use. To address this issue this study introduces an indexing approach toevaluate the suitability of energy storages for power system applications. Four different energy storages (doublelayercapacitor, flywheel, lead–acid battery, lithium-ion battery) are tested for four typical energy storage applications(frequency regulation, voltage support, capacity firming and energy time-shift). The suitability indexallows a simple and intuitive way to compare and rank the suitability of energy storages.

  • 7.
    Pham, Cong-Toan
    et al.
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Månsson, Daniel
    KTH, School of Electrical Engineering and Computer Science (EECS), Electromagnetic Engineering.
    Experimental validation of a general energy storage modelling approach(Part III)2018In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 20, p. 542-550Article in journal (Refereed)
    Abstract [en]

    Current challenges in the electric grid progression demand energy storages to cope with any imbalances betweensupply and demand side. Application possibilities of energy storages are numerous, but the requirements varyfrom case to case. However, not every storage technology operates equally to be useful in any situation. In fact,the feasibility of energy storages depend on their technical characteristics, i.e., for example efficiency, responsetimes, power rating and capacity for a selected application. Comparing and assessing different storage options isimperative for decision-making, which requires an in-depth understanding of the technology and its dynamics.Hence, a general model approach of energy storages as equivalent circuit models has been proposed to unify andanalyze storages of different physical backgrounds. This allows a more direct and intuitive evaluation of energystorages tested in a specific application. This paper focuses on the experimental validation of energy storages(ultra-capacitor, li-ion battery, lead-acid battery and flywheel) to be uniformly described in one general model. Asimple and budget friendly experimental setup to test the storages is designed.

  • 8.
    Wu, Yuan
    et al.
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Chen, Guorong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Wang, Zhuyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhao, Yin
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Shi, Liyi
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Zhu, Jie-Fang
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Zhang, Meihong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Jia, Rongrong
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    Yuan, Shuai
    Shanghai Univ, Res Ctr Nanosci & Nanotechnol, Shanghai 200444, Peoples R China.
    In situ constructed Ag/C conductive network enhancing the C-rate performance of Si based anode2018In: Journal of Energy Storage, E-ISSN 2352-152X, Vol. 17, p. 102-108Article in journal (Refereed)
    Abstract [en]

    Poor intrinsic electrical conductivity as well as considerable volume change during lithium alloying/dealloying process has been a critical defect for high theoretical capacity silicon-based anodes. In our work, we demonstrate the synthesis design of multiscale recombined dendritic Si/Ag/C anode for high energy density LIBs via compositing bulky silicon with uniformly distributed Ag NPs, followed by a carbon source PDA (polydopamine) coating step. Here Ag NPs are generated by an in situ redox reaction between Ag+ and PDA, no need for additional reducing agents. According to the characterization analysis, the robust porous Si/Ag/C structure can provide channels for fast Li+ diffusion and electron conduction, promoting the formation of a thinner and more stable SEI film. As a result, the Si/Ag/C composite anode still yields a relatively high residual capacity of 1422.1 mAh g (1) after 100 cycles at 0.2 A g (1). In addition, it remains 633.1 mAh g (1) after 500 cycles at a high current density of 8 A g (1).

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