Statistical optimization of supercapacitor pilot plant manufacturing and process scale-up

In recent years, electrical double layer capacitor (EDLCs) has become one of the most popular energy storage devices. This can be attributed to its high capacity, long life cycle and fast charge/discharge rates. However, it has some drawbacks – mainly it stores less amount of energy than batteries. Hence, there is a need to optimize the EDLC to increase its capacity and decrease its equivalent series resistance (ESR), resulting in a supercapacitor that is able to charge quickly and will hold a large amount of energy for a long time. This thesis presents a design, build and setup process of a supercapacitor pilot plant in the University of Nottingham Malaysia Campus for manufacturing and optimization of EDLCs. Two packages were considered, cylindrical and coin type packages. In addition, the design of a manufacturing process flow, with details on steps for fabrication, which will meet specific standards (BS EN 62391-1:2006, BS EN 62391-2-1: 2006, BS EN 62391-2-1: 2006 and DOD-C-29501/3 NOT 1) for quality and throughput for both the packaging types is discussed. Following this, significant factors of the fabrication process were identified and optimized by adopting the Taguchi design of experiment (DOE) methodology. Results of the optimization process show that the most significant factors that affect the EDLC capacitance are PVDF % (polyvinylidene diflouride) and mixing time; the optimum values are determined to be 5% and 3 hours respectively. In the case of ESR optimization, the most significant factors are PVDF % and carbon black %. The optimum values are 5% for both. Using these optimized values, a final prototype EDLC was fabricated. The capacitance value obtained for the cell was 54.70mF. The final EDLC prototypes were tested according to the international standards (ISO) and compared with the supercapacitors available in the market. Results indicated that the electrochemical performance of the prototypes has a good resemblance to the performance of the supercapacitors available in the market. A selected prototype samples were sent for benchmark testing to companies in mobile applications in Korea and the Netherlands to confirm that the prototypes meet the required standards. Finally the research work sets the basis for integrating genetic algorithms with the Taguchi technique for future research in improving the optimization process for robust EDLC fabrication

Statistical optimization of supercapacitor pilot plant manufacturing and process scale-up

In recent years, electrical double layer capacitor (EDLCs) has become one of the most popular energy storage devices. This can be attributed to its high capacity, long life cycle and fast charge/discharge rates. However, it has some drawbacks – mainly it stores less amount of energy than batteries. Hence, there is a need to optimize the EDLC to increase its capacity and decrease its equivalent series resistance (ESR), resulting in a supercapacitor that is able to charge quickly and will hold a large amount of energy for a long time. This thesis presents a design, build and setup process of a supercapacitor pilot plant in the University of Nottingham Malaysia Campus for manufacturing and optimization of EDLCs. Two packages were considered, cylindrical and coin type packages. In addition, the design of a manufacturing process flow, with details on steps for fabrication, which will meet specific standards (BS EN 62391-1:2006, BS EN 62391-2-1: 2006, BS EN 62391-2-1: 2006 and DOD-C-29501/3 NOT 1) for quality and throughput for both the packaging types is discussed. Following this, significant factors of the fabrication process were identified and optimized by adopting the Taguchi design of experiment (DOE) methodology. Results of the optimization process show that the most significant factors that affect the EDLC capacitance are PVDF % (polyvinylidene diflouride) and mixing time; the optimum values are determined to be 5% and 3 hours respectively. In the case of ESR optimization, the most significant factors are PVDF % and carbon black %. The optimum values are 5% for both. Using these optimized values, a final prototype EDLC was fabricated. The capacitance value obtained for the cell was 54.70mF. The final EDLC prototypes were tested according to the international standards (ISO) and compared with the supercapacitors available in the market. Results indicated that the electrochemical performance of the prototypes has a good resemblance to the performance of the supercapacitors available in the market. A selected prototype samples were sent for benchmark testing to companies in mobile applications in Korea and the Netherlands to confirm that the prototypes meet the required standards. Finally the research work sets the basis for integrating genetic algorithms with the Taguchi technique for future research in improving the optimization process for robust EDLC fabrication

EDLC Capacitance Optimization Using the Taguchi Technique

Abstract -The Taguchi technique was applied in this work to maximize the capacitance of a supercapacitor. The key issue in applying the Taguchi technique is to identify and control the process factors that will lead to optimized capacitance of the supercapacitor. The reported method used in literature is the trial and error method (optimizing one factor at a time). DOE (Design of Experiments) allows multiple parameters to be evaluated with a limited number of experiments. With the use of the Taguchi methodology, in this paper, the number of required experiments was reduced from (3 3 ) = 27 experiments to only 9 experiments while at the same time producing a more robust product. The main materials used for the fabrication process are activated carbon (AC), which was used as the active material; carbon black (CB) which was used as the conducting agent; and PVDF (Polyvinylidene fluoride) polymer, which was used as binder agent. A total of nine capacitors were fabricated, and the following factors were varied: PVDF percentage, CB percentage and mixing time. This experiment was performed to find the dominant parameter affecting the capacitance. A 1 M (LiClO4) sample in an acetonitrile organic solution was used as an electrolyte, and a 13 mm diameter disc-shaped super-capacitors were fabricated. The cells capacitance was found to range from 24.91 to 51.23 mF with the different process factors. The properties of the fabricated cells were measured using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and charge-discharge measurements. Auto lab (PGSTAT302N) was used to perform the measurements. The results indicated that the binder percentage and mixing time have a significant effect on the capacitance. A final confirmation cell was fabricated using the optimised factors