Develop nanoscale advanced materials for high-pressure water electrolyzers and high-voltage Li-ion batteries in the 5 V range in collaboration with NASA GRC and JPL, complementing parallel non-overlapping efforts carried out under PR NASA EPSCoR.

Sub-Theme A: Li ion batteries

 

X-ray diffraction study on the material was carried out in the 2θ range of 15-70 degrees. Signature of the Li2MnO3 phase was clearly observed with the peaks in between the 2θ range of 20-25 degrees. However the splitting of the peak at around 44 degrees was also observed which might be due to the improper mixing of the two compositions namely Li2MnO3 and LiNi0.5Mn0.5O2. Further work is in progress to study and over come the drawbacks of the present study. Electrochemical performance of the material was also checked. A slurry of the active material with the acetylene black and PVDF in a proper wt% ratio (80:10:10) was made using NMP and coated onto the aluminum foil which act as a current collector. Electrodes of desired area were punched out of the foil and coin cells (2032) were made using metallic lithium as anode. Removal of the Li2O, out of Li2MnO3 can has been observed at ~4.5V with a long flat plateau. Removal of Li2O is known to be irreversible. However it leaves host MnO2 in the base matrix, in which lithium can be inserted back giving rise to LiMnO2. Such kind of compositions with manganese oxidation state close to +4 and Nickel oxidation state close of +2 is not easy to fabricate at the beginning. Discharge and charge capacities of the material were calculated using initial weight of the material loaded on to the foil. A discharge capacity of ~190 mAh/g has been obtained at a charging rate of 5 mA/g. Further investigations related to the material are under study. Focus will be on the synthesis of the material using co-precipitation method.

One undergraduate and one graduate student are working on high-energy density Li ion rechargeable batteries and high energy density electrochemical systems for 18hr/week working hours.

 

 

Co-PI:  Ram Katiyar

Graduate Student:

Lorain Torres, USA, Physics, studies on layered cathode materials, Hispanic, Female

Undergraduate student:

Samuel Nieves, USA, Computer Science, Server control and Data analysis

 

Scientific presentations:

1. Effect of the different carbon source of nanocomposite LiFePO4, Arum Kumar, R. Thomas, M. Tomar, and R. S. Katiyar, 218th ECS Meeting, Las Vegas, Nevada, (USA), October 10-15, 2010

2. Graphane-LiFePO4 nanocomposite cathode for Lithium ion batteries, Arum Kumar, Chitturi Venkateswara Rao, R. Thomas, M. S. Tomar, Y. Ishikawa, and R. S. Katiyar, 35th International Conference & Exposition on Advanced Ceramics & Composites (ICACC), Daytona Beach, Florida, January 23-28, 2011

3. Dependence of LiFePO4 electrochemical properties on the types of conductivity enhancing additives, Arum Kumar, R. Thomas, M. S. Tomar, and R. S. Katiyar, 219th ECS Meeting, Montreal, QC, Canada, May 1-6, 2011

4.    LiNi0.66Co0.17Mn0.17O2 as a potential layered cathode material for Li-ion batteries, J.J. Saavedra-Arias,  L. Torres,  A. Manivannan, Y. Ishikawa, and R.S. Katiyar, 219th ECS Meeting, Montreal, Canada, May 1-6, 2011

 

Sub-Theme B: Water Electrolysis

 

Samples containing Iridium and Ruthenium electrodeposited onto Platinum black were previously prepared and compared to Platinum black as received and to Platinum exposed to the Iridum and Ruthenium with no applied potential. Scanning Electron Microscopy (SEM) was performed and no clear or obvious differences are present. However mappings clearly show strong presence of Iridium and Ruthenium on top of the Platinum on both electrodeposited samples. While the as received Platinum black does not, and the blank with no applied potential shows a vague presence of these elements most likely due to some adsorption of the precursors. X-ray photoelectron Spectroscopy (XPS) was also performed on all samples and high resolution analysis indicates as expected that no Iridium and Ruthenium are present on the as received Platinum, but in the no applied potential sample the presence of Ruthenium was detected. This was expected as Ruthenium adsorbs spontaneously on Platinum, nonetheless in our RoDSE (Rotating Disk Electrode) method it presents no problem as it will also undergo reduction upon polarization of the particles.  Both electrodeposited samples had the Iridium and Ruthenium signal of the 4f and 3p peaks respectively, and this in contrast to the blanks is clear indication, that electrochemical reduction onto the Platinum samples was performed. The binding energies of the Iridium area highly suggest a metallic state, but in the Ruthenium other than a metallic state might be present, and that has to be analyzed to make sure. Cyclic voltammograms (CV) of the Pt black, (IrRu)/Pt black (I) and (IrRu)/Pt black (II) are presented and the electrochemical response is different for those containing the Ru and Ir, specifically in the Hydrogen adsorption and desorption regions. Which suggest changes on the surface of the Platinum. For those samples containing Ru the potential range was limited to -0.2 – 0.6 V vs Ag|AgCl, to prevent oxidation of the Ruthenium to the soluble oxide. Finally, to complement the presence of the electrodeposited material, in this case Ruthenium CO Stripping was performed, and the change in currents and onset potential is evident, still we plan to normalize these results to current density j.