Design and experimental verification of a fuel cell/supercapacitor passive configuration for a light vehicle

The fuel cell/supercapacitor passive configuration without using any DC/DC converters is promising in auto-motive applications as it can downsize the fuel cell stack, maintain the peak power capability, improve the system efficiency, and remove the need of additional control. This paper presents the design and characterization of a fuel cell/supercapacitor passive hybrid system for a 60 V light vehicle. A detailed design procedure for the passive hybrid test platform is presented with each component modelled and experimentally verified. The voltage error of the fuel cell and the supercapacitor model in the steady state is within 2% and 3%, respectively. Experimental results also validate the function of the passive configuration under conditions of a step load and a drive cycle. The simulation model of the passive hybrid system matches the measurements when a step load current is applied. The supercapacitor provides the transient current due to its smaller resistance while the fuel cell handles the steady state current, which makes it possible to downsize the fuel cell stack. For the drive cycle examined in this paper, the fuel cell stack can be downsized to one third of the load peak power

Master of Science

thesisElectrochemical capacitors, or "supercapacitors", are an electrochemical energy storage technology with high-power density and long cycle life compared to batteries. Supercapacitors have many promising applications in electric vehicles, renewable energy storage, consumer electronics, environmental sensors, biomedical implants, and grid energy storage. Conductive polymers are a material of interest for supercapacitor energy storage because of their ability to store energy by both electric double layer capacitance and "pseudocapacitance" (surface reduction-oxidation reactions). Polypyrrole is a widely used conductive polymer for supercapacitor electrodes, as well as in lithium-ion batteries. For applications in environmental sensors, transient electronics, and implantable devices, it is necessary to find supercapacitor electrode materials that are easily biodegradable. A variation of polypyrrole exhibiting methyl carboxylate side chains, which we call "MPC polymer," is presented in this thesis as a dissolvable supercapacitor electrode. It is, to the best of our knowledge, introduced for the first time as a dissolvable electrochemical energy storage material. The supercapacitor characteristics of MPC polymer are characterized for planar electrodes as well as a nanocellulose-based composite. The MPC polymer is found to have capacitance, cycle life, and impedance characteristics comparable to state-of-the-art polypyrrole

Supercapacitor Sizing for Fast Power Dips in a Hybrid Supercapacitor—PEM Fuel Cell System

Polymer electrolyte membrane fuel cell (PEM FC) operation is likely to be characterized by voltage dips on timescales shorter than 1 s, arising from temporary flooding of gas channels or porous layers, particularly when the FC is operated at high humidity levels. If supercapacitors are employed in hybrid systems, they can make up for the temporary lack of energy produced by the FC. However, the steep slopes of the voltage dips affect the energy that can be actually delivered by the supercapacitor because of its series impedance, and this should be taken into account when sizing it. This paper presents a simplified approach for sizing the supercapacitor, based on some observed peculiar features of the FC dips, which allow a simple but accurate model for the evaluation of the supercapacitor response to such dips. The validity of such an approach is supported by simulation and experimental results performed on a single PEM FC and on a supercapacitor

Performance improvement of electrochemical capacitors through the integration of advanced materials and the cell configuration assessment

209 p.The electrochemical capacitors or supercapacitors are envisioned as potential next-generation energy storage systems because of their excellent storage capacity, power density, and long-term durability. However, all these advantages are overshadowed by their poor energy density. Thus, this thesis aims to achieve a high-energy supercapacitor device without compromising its power performance to make them more commercially viable for many applications. The research work is associated with the improvement of the supercapacitors in different device configurations, such as EDL, asymmetric, and hybrid LIC systems by integration of advanced material and cell design. The results obtained from the studies of different supercapacitor systems demonstrate that the variation in electrode mass, cell voltage, and electrolyte has a huge impact on the overall electrochemical performance, stability, life expectancy, and safety of the device. Therefore, careful optimization of cell design and advancement in electrode materials retains the high importance driving factors of the supercapacitors for the development of future energy storage technology

Performance improvement of electrochemical capacitors through the integration of advanced materials and the cell configuration assessment

209 p.The electrochemical capacitors or supercapacitors are envisioned as potential next-generation energy storage systems because of their excellent storage capacity, power density, and long-term durability. However, all these advantages are overshadowed by their poor energy density. Thus, this thesis aims to achieve a high-energy supercapacitor device without compromising its power performance to make them more commercially viable for many applications. The research work is associated with the improvement of the supercapacitors in different device configurations, such as EDL, asymmetric, and hybrid LIC systems by integration of advanced material and cell design. The results obtained from the studies of different supercapacitor systems demonstrate that the variation in electrode mass, cell voltage, and electrolyte has a huge impact on the overall electrochemical performance, stability, life expectancy, and safety of the device. Therefore, careful optimization of cell design and advancement in electrode materials retains the high importance driving factors of the supercapacitors for the development of future energy storage technology