Qualification: 
Ph.D
dsgopalan20710@aims.amrita.edu

Dr. Dhamodaran Santhanagopalan is an Associate Professor and DST Ramanujan Fellow at Amrita Center for Nanosciences and Molecular Medicine. Before joining the center, he was a Postdoctoral Fellow at the Laboratory for Energy Storage and Conversion, University of California, San Diego, for three years. Prior to postdoctoral work, he was a faculty at Physics Department, IIT Kanpur, for about three and a half years. Dr. Dhamodharan received PhD from University of Hyderabad, and M.Phil. and M.Sc degrees in Physics from Pondicherry University. During his postdoctoral work he was part of the Energy Frontier Research Centre led by Stony Brook University, funded by US Department of Energy. During this tenure, he was also a Guest researcher at Brookhaven National Laboratory, New York, and Pacific Northwest National Laboratory, Washington. As a part of this work, he established for the first time, fabrication of electrochemically active solid-state nano-batteries using focused ion beams. This significant contribution enabled in situ galvanostatic biasing of nano-batteries in the TEM to investigate interface effects, a bottle-neck in energy storage devices. During his tenure at IIT Kanpur, he developed several ion beam facilities and a GaN growth facility for high quality nanostructures with novel morphologies that are useful for opto-electronic applications. Two of the GaN nanostructure images were published as journal cover pages in Materials Today (2011) and Nano Today (2012). He has over 50 peer reviewed journal publications and 10 proceedings to his credit. He has been invited as a speaker in several national and international conferences. He is also an active reviewer for several international journals on topics related to his research interests. In the recent past, he has worked on micro/nano-fabrication and semiconductor nano-materials. Dr. Dhamodharan is currently focusing on energy storage technologies such as, lithium ion batteries, all-solid-state batteries and supercapacitors. The goal is to significantly improve both energy and power densities without compromising safety and cycling stability.

Publications

Publication Type: Journal Article

Year of Publication Publication Type Title

2017

Journal Article

A. K. Haridas, Gangaja, B., Srikrishnarka, P., Unni, G. E., A. Nair, S., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Spray pyrolysis-deposited nanoengineered TiO2 thick films for ultra-high areal and volumetric capacity lithium ion battery applications”, Journal of Power Sources, vol. 345, pp. 50 - 58, 2017.[Abstract]


Abstract Energy storage technologies are sensitively dependent on electrode film quality, thickness and process scalability. In Li-ion batteries, using additive-free titania (TiO2) as electrodes, we sought to show the potential of spray pyrolysis-deposited nanoengineered films with thicknesses up to 135 μm exhibiting ultra-high areal capacities. Detailed electron microscopic characterization indicated that the achieved thick films are composed of highly crystalline anatase TiO2 particles with sizes on the order of 10–12 nm and porous as well. A 135 μm thick film yielded ultra-high areal and volumetric capacities of 3.7 mAh cm−2 and 274 mAh cm−3, respectively, at 1C rate. Also the present work recorded high Coulombic efficiency and good cycling stability. The best previously achieved capacities for additive-free TiO2 films have been less than 0.25 mAh cm−2 and With additives, best reported areal capacity in the literature has been 2.5 mAh cm−2 at 1C rate, but only with electrode thickness as high as 1400 μm. Formation of through-the-thickness percolation of Ti3+ conductive network upon lithiation contributed substantially for the superior performance. Spray pyrolysis deposition of nanoparticulate TiO2 electrodes have the potential to yield volumetric capacities an order of magnitude higher than the other processes previously reported without sacrificing performance and process scalability. More »»

2017

Journal Article

B. Gangaja, Chandrasekharan, S., Vadukumpully, S., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Surface chemical analysis of CuO nanofiber composite electrodes at different stages of lithiation/delithiation”, Journal of Power Sources, vol. 340, pp. 356 - 364, 2017.[Abstract]


Abstract High aspect ratio, electrospun CuO nanofibers have been fabricated and tested for its electrochemical performance as lithium ion battery anode. These nanofibers are composed of CuO nanoparticles about 35–40 nm in size forming good inter-connected network. Fabricated half cells maintained specific capacity of 310 mAh g−1 at 1C rate for 100 cycles and stabilized capacity of about 120 mAh g−1 at 5C rate for 1000 cycles. Ex situ x-ray photoelectron spectroscopy (XPS) was performed to understand the electrodes surface chemical changes at the end of first discharge, first charge and after tenth charge. The solid electrolyte interface (SEI) layer comprised of LiF, Li2CO3 and Li2O while their quantity varied depending on the stage of lithiation/delithiation. Initially, no copper signal is observed on the surface of the \{SEI\} layer. However, in situ sputtering of the electrodes in the \{XPS\} chamber revealed that at the end of first discharge, formation Cu0 with detectable fraction of LixCuO2 and hydroxide in the \{SEI\} layer. At the end of first charge, a large fraction of Cu2O phase with a small fraction of hydroxide is observed. At the end of 10th charge no change in \{SEI\} layer content but increase in thickness was observed. More »»

2017

Journal Article

S. P. Madhusudanan, Gangaja, B., Shyla, A. G., A. Nair, S., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Sustainable chemical synthesis for phosphorus-doping of TiO2 nanoparticles by upcycling human urine and impact of doping on energy applications”, ACS Sustainable Chem. Eng, pp. 2393–2399, 2017.[Abstract]


Recently, there has been significant research interest toward sustainable chemical synthesis and processing of nanomaterials. Human urine, a pollutant, requires energy intensive processing steps prior to releasing into rivers and oceans. Upcyling urine has been proposed and practiced as a sustainable process in the past. Doping is one of the foremost processes to elevate the functionality of nanomaterials depending on the applications it is sought for. Phosphorus doping in to TiO2 nanomaterials has been of research interest over a decade now, that has been chiefly done using acidic precursors. Here we demonstrate, upcycling urine, a sustainable process for phosphorus doping into TiO2 lattice. Upon doping the changes in morphology, surface chemistry and band gap is studied in detail and compared with undoped TiO2 that is prepared using deionized water instead of urine. X-ray photoelectron spectroscopy confirmed that the P was replacing Ti in the lattice and exists in P5+ state with a quantified concentration of 2.5–3 at %. P-doped nanoparticles were almost 50% smaller in size with a lower concentration of surface −OH groups and a band gap increase of 0.3 eV. Finally, impact of these changes on energy devices such as dye-sensitized solar cells and li-ion batteries has been investigated. It is confirmed that P-doping induced surface chemical and band gap changes in TiO2 affected the solar cell characteristics negatively, while the smaller particle size and possibly wider surface channels improved Li-ion battery performance. More »»

2017

Journal Article

J. John, Gangaja, B., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Conformal coating of TiO2 shell on silicon nanoparticles for improved electrochemical performance in Li-ion battery applications”, Electrochimica Acta, vol. 235, pp. 191 - 199, 2017.[Abstract]


Abstract A scalable wet chemical process for conformal TiO2 coating on silicon nanoparticles is investigated for Li-ion battery applications. The stable core-shell composite nanoparticles along with polyacrylic acid (PAA) binder was studied as an anode in Li-ion batteries and compared with bare-Si as a control. By limiting the charge capacity to 1500 mAh g−1, we established stable cycling (zero fade) for over 50 cycles for the core-shell compared to inferior stability (only 30% capacity retention) of the bare-Si nanoparticles at 0.1C rate. Stable capacity of 800 mAh g−1 at 1C rate over 100 cycles was also demonstrated for the core-shell nanoparticle electrode. Transmission electron microscopy and X-ray photoelectron spectroscopy characterizations indicate that in absence of TiO2 the solid electrolyte interface (SEI) layer which forms around Si was about 8–10 nm and composed of Li2O and LiF. In contrast, the \{SEI\} layer around the TiO2 shell has been thinner (about 2–3 nm) and composed of LiF and LixPFyOz, that stabilized the surface leading to improved cycling stability. Thinner \{SEI\} layer and its composition led to lower charge transfer resistance while the interface between the composite and the Cu-current collector has better adhesion compared to the bare-Si electrode. Impedance spectroscopy measurements confirmed the above. More »»

2016

Journal Article

S. Mohapatra, Shantikumar V Nair, Dr. Dhamodaran Santhanagopalan, and Alok Kumar Rai, “Nanoplate and mulberry-like porous shape of CuO as anode materials for secondary lithium ion battery”, Electrochimica Acta, vol. 206, pp. 217-225, 2016.[Abstract]


Facile hydrothermal synthesis of nanoplate and mulberry-like porous shape of CuO nanostructures was developed as anode materials for application in lithium ion batteries. The powder X-ray diffraction patterns of both the samples were indexed well to a pure monoclinic phase of CuO with no impurities. The CuO sample synthesized at different pH and reaction temperature exhibited nanoplate with average width and length of ∼150-300 nm and ∼300-700 nm and mulberry-like porous shape of CuO with average length of ∼300-400 nm. Electrochemical tests show that the lithium storage performances of both the nanoplate and mulberry-like samples are influenced more closely to its structural aspects than their morphology and size factors. The CuO nanoplate electrode exhibits high reversible charge capacity of 279.3 mAh g-1 at 1.0C after 70 cycles, and a capacity of 150.2 mAh g-1 even at high current rate of 4.0C during rate test, whereas the mulberry-like porous shape of CuO anode delivers only 131.4 mAh g-1 at 1.0C after 70 cycles and 121.7 mAh g-1 at 4.0C. It is believed that the nanoplate type architecture is very favorable to accommodate the volume expansion/contraction and aggregation of particles during the cyclic process. In contrast, the mulberry-like porous morphology could not preserve the integrity of the structure and completely disintegrated into nanoparticles during Li+ ion insertion/deinsertion due to the loose contact between the particles. © 2016 Elsevier Ltd. All rights reserved.

More »»

2016

Journal Article

P. Preetham, Mohapatra, S., Shantikumar V Nair, Dr. Dhamodaran Santhanagopalan, and Alok Kumar Rai, “Ultrafast pyro-synthesis of NiFe2O4 nanoparticles within a full carbon network as a high-rate and cycle-stable anode material for lithium ion batteries”, RSC Advances, vol. 6, pp. 38064-38070, 2016.[Abstract]


NiFe2O4 nanoparticles fully anchored within a carbon network were prepared via a facile pyro-synthesis method without using any conventional carbon sources. The surface morphology was investigated using field-emission scanning electron microscopy, which confirmed the full anchoring of NiFe2O4 nanoparticles within a carbon network. The primary particle size of NiFe2O4 is in the range of 50-100 nm. The influence of the carbon network on the electrochemical performance of the NiFe2O4/C nanocomposite was investigated. The electrochemical results showed that the NiFe2O4/C anode delivered a reversible capacity of 381.8 mA h g-1 after 100 cycles at a constant current rate of 1.0C, and when the current rate is increased to a high current rate of 5.0C, a reversible capacity of 263.7 mA h g-1 is retained. The obtained charge capacity at high current rates is better than the reported values for NiFe2O4 nanoparticles. The enhanced electrochemical performance can be mainly ascribed to the high electrical conductivity of the electrode, the short diffusion path for Li+ ion transportation in the active material and synergistic effects between the NiFe2O4 nanoparticles and carbon network, which buffers the volume changes and prevents aggregation of NiFe2O4 nanoparticles during cycling. © The Royal Society of Chemistry 2016.

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2016

Journal Article

Za Wang, Dr. Dhamodaran Santhanagopalan, Zhang, Wc, Wang, Fc, Xin, H. Lc, He, Kc, Li, Jd, Dudney, Nd, and Meng, Y. Sa, “In situ STEM-EELS observation of nanoscale interfacial phenomena in all-solid-state batteries”, Nano Letters, vol. 16, pp. 3760-3767, 2016.[Abstract]


Behaviors of functional interfaces are crucial factors in the performance and safety of energy storage and conversion devices. Indeed, solid electrode-solid electrolyte interfacial impedance is now considered the main limiting factor in all-solid-state batteries rather than low ionic conductivity of the solid electrolyte. Here, we present a new approach to conducting in situ scanning transmission electron microscopy (STEM) coupled with electron energy loss spectroscopy (EELS) in order to uncover the unique interfacial phenomena related to lithium ion transport and its corresponding charge transfer. Our approach allowed quantitative spectroscopic characterization of a galvanostatically biased electrochemical system under in situ conditions. Using a LiCoO2/LiPON/Si thin film battery, an unexpected structurally disordered interfacial layer between LiCoO2 cathode and LiPON electrolyte was discovered to be inherent to this interface without cycling. During in situ charging, spectroscopic characterization revealed that this interfacial layer evolved to form highly oxidized Co ions species along with lithium oxide and lithium peroxide species. These findings suggest that the mechanism of interfacial impedance at the LiCoO2/LiPON interface is caused by chemical changes rather than space charge effects. Insights gained from this technique will shed light on important challenges of interfaces in all-solid-state energy storage and conversion systems and facilitate improved engineering of devices operated far from equilibrium. More »»

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