Higher pressures during pelletization and lower frequencies led to higher capacitance of phosphatic clay. Adding the diatoms Synedra and Navicula to clay increased capacitance, though not significantly. The optimum conditions for pelletizing clay to measure capacitance were 8000 psi pressure and low frequencies. While clay-diatom mixtures showed enhanced capacitive properties, more experiments are needed using higher diatom percentages and other variables to maximize supercapacitor performance.

1. 1Vital, D., 1Reith, D., 1Coughlin, C., 1Integlia, R., 1Srinivasan, S., 1Birky, B., 1Albarelli, G., 1Defino, P., 2Spaulding S.A., & 1Horton, M.D.
• Higher frequency led to lower capacitance (Table
1)
• Best quality pellets were obtained at 8000 psi (see
image 1 & 2)
• Addition of diatoms to the clay led to higher
capacitance for any frequency between 100 to
1000 psi (Fig.1) although not statistically
significant (p=0.9) (Table 2)
• Results showed that the optimum condition to
pelletize the clay for capacitance measurement is
at 8000psi using low frequencies. The addition of
diatoms at 4% by weight enhanced the capacitive
property of the clay although not statistically
significant suggesting that an increase in the
percentage of the mixture needs to be explored.
This clearly suggests that phosphatic clay mixed
with diatoms is a potential material in the
production of supercapacitor but more
experiments on different variables need to be
conducted to obtain maximum capacitance.
• Higher ratio of diatoms( Synedra and Navicula) to
clay( 10,20,30,& 50%)
• Test sample for frequencies lower than 100Hz
• Obtain thinner pellets for further capacitance
evaluation using the following formula
• Mix clay with other diatom species (Cyclotella, and
Thalassiosira)
• Conduct electrochemical analysis
• Stack pellets for series and parallel configurations.
• Test the clay porosity to further the electrical
analysis evaluation
References
1. Murray, Haydn H. "Overview—clay mineral applications." Applied Clay
Science 5.5 (1991): 379-395.
2. Azeez, Asif Abdul, et al. "Epoxy clay nanocomposites–processing, properties and
applications: A review." Composites Part B: Engineering 45.1 (2013): 308-320.
3. Borges RS, Reddy ALM, Rodrigues MF, et al. Supercapacitor operating at 200
degrees celsius. Scientific reports. 2013; 3:2572. doi: 10.1038/srep02572.
4. Jeffryes C, Campbell J, Li H, Jiao J, Rorrer G. The potential of diatom
nanobiotechnology for applications in solar cells, batteries, and
electroluminescent devices. Energy & Environmental Science. 2011;4(10):3930.
doi: 10.1039/c0ee00306a.
5. http://www.keywordsking.com/c3luZWRyYQ/
6. http://www.keywordsking.com/bmF2aWN1bGE/
7. Chmiola, John and Yushin , G. and Gogotsi, Y. and Portet, Christele and Simon,
Patrice and Taberna, Pierre-Louis ( 2006) Anomalous Increase in Carbon
Capacitance at Pore Sizes Less Than 1 Nanometer. Science Magazine, vol. 313
(n° 5794). pp. 1760-1763. ISSN 0036-8075
8. http://www.digole.com/index.php?productID=879
Acknowledgement.
My sincere thanks to:
• Florida Polytechnic University
• Ms. Elisabeth Shea
• SGA at Florida Poly
• Physics Club at Florida Poly
• SPS for the poster template
1Florida Polytechnic University, 4700 Research Way, Lakeland, FL
2University of Colorado, 1234 Innovation Dr., 80303, Boulder, CO
Previous research conducted at Florida Polytechnic
University reported that addition of diatoms
(Aulacoseira) appears to enhance the quality of
phosphatic clay taken from Polk County for industrial
applications. This gypsum-rich clay, is a byproduct of
the phosphate mining industry and not currently in use
due to its poor quality for agricultural and industrial
applications. Diatoms are special kind of algae with
siliceous cell walls that have been explored for various
industrial applications. The species of Synedra and
Navicula are commonly distributed in the fresh waters
of the area. This research aims to investigate the
potential of the phosphatic clay-diatom mixture as a
potential material in developing a supercapacitor. The
success of this research will open up a novel idea in
engineering new materials for renewable energy
applications. This will ultimately enhance the socio-
economic condition not only in Polk County but the
entire country and around the globe
Background
Why Clay?
• By-product of phosphate mining with no agricultural
or industrial use.
• Low cost applications in ceramics, cement, and
asphalt emulsions (Murray et al., 1991)
• Probable applications in aerospace, defense,
automobile, etc. (Azeez et al., 2013)
• Probable capacitive effects (Borges et al. 2013)
Why diatoms?
• Potential Nano-biotechnology for applications in
solar cells, batteries,etc (Jeffryes et al. 2011)
• Probable effect on performance because of porous
shell (Chmiola et al. 2006)
• Pores larger than electrolyte ion for high
capacitance (Chmiola et al. 2006)
• Commonly found in the freshwaters of Florida
Motivation
Objective
Background
Why Supercapacitor?
• Higher capacitance than electrolytic capacitors
• Ability to store 10 to 100 X more energy per unit volume or
mass
• Capacity to accept and deliver charge much faster than
batteries
• Applications in electric vehicles and smart phones
• To investigate the potential use of phosphatic clay and the
clay mixed with diatoms as a potential material to develop
a supercapacitor
• To determine the optimum condition to pelletize the clay
and the clay-diatom mixture
• To test and analyze the electrical properties of pelleted
clay and clay-diatom mixture
Method & Experiment
• Synedra and Navicula cultured under controlled
conditions; light (200-300 foot-candles) at 20-220 C
temperature for 8 hour light-16 hours dark photoperiod.
• Two-week old cells were harvested and dried for 24 hours
at room temperature.
• Clay was oven-dried at 210°C for 24 hours, and powdered
using mortar and pestle.
• Two sets of 5 g of clay and clay-diatom mixture were
prepared
• Some clay were pelletized from 5000-8000 psi using pellet
press while some were mixed with diatoms Synedra and
Navicula in 96 clay: 4 diatom by weight and pelletized
accordingly.
• Silver paint electrodes and leads were attached to each
side of the pellets.
• Capacitance at several frequencies was measured using a
Keysight U17733C Handheld LCR Meter ( at
0.70±0.05Vrms )
Data
Assembled Supercapacitor
Fig.1. Average capacitance measurements of the clay and clay-diatom mixture pellets at
varying frequencies (n=3; ±𝐬𝐭𝐚𝐧𝐝𝐚𝐫 𝐞𝐫𝐫𝐨𝐫).
Supercapacitor Model
Table 1.Average capacitance measurements of clay and clay-diatom mixture pellets obtained at
8000psi (n=3)
Synedra fresh from culture Navicula fresh from culture
Dried ClayFresh Clay
Analysis
Conclusion
Results
Future Plans
Clay pelletized at 8000psiClay pelletized under 8000psi
1 2
Table 2. Result of the analysis if variance (ANOVA) testing the significant difference in the
capacitance measurements between the clay and the clay-diatom mixture at p<0.05 (n=3)
Capacitance formula
( 8 in reference)
(5 in reference) (6 in reference)