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 Title

2019

B. Gangaja, Nair, S., and Dr. Dhamodaran Santhanagopalan, “Solvent-Controlled Solid-electrolyte Interphase layer Composition of a High Performance Li4Ti5O12 Anode for Na-ion Battery Applications”, Sustainable Energy and Fuels, vol. 3, pp. 2490-2498, 2019.[Abstract]


Intrigued by the unlimited availability, low cost and high redox potential of sodium, the rechargeable sodium ion battery (SIB) has attracted significant research interest as a supplement to lithium ion batteries. However, an optimized electrolyte for SIB has still not been developed, which in turn affects the performance of the electrode materials. Herein, we have elucidated the influence of electrolyte formulations in the design of a high performance lithium titanate (LTO) anode for sodium ion battery applications. NaPF6 salt in three solvent formulations (diglyme (DiG), propylene carbonate (PC), and ethylene carbonate-dimethyl carbonate (EC/DMC)) were explored to investigate the electrochemical performance of solvothermally synthesized surface engineered LTO samples. An unprecedented rate capability (up to 300C), cycling stability (1000 cycles) and wide temperature range of operation (-10 °C to 55 °C) were demonstrated by the LTO-diglyme based electrode, the highest rate performance reported so far for LTO-based sodium ion battery anodes. Detailed surface chemical analysis via ex situ XPS measurements was performed on the pristine and cycled electrodes in each electrolyte to rationalize the electrode's performance and realize the solid-electrolyte interphase (SEI) evolution and its composition. XPS confirmed the formation of a thin, protective SEI layer in DiG based electrolyte composed of mixed organic/inorganic components resulting in the excellent rate and cycling capabilities. In contrast, PC-and EC/DMC-based electrolytes formed a relatively thicker, unstable, organic-rich SEI layer, leading to inferior electrochemical performance.

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2019

A. P. Varghese, Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Cobalt Oxide Thin Films for High Capacity and Stable Li-ion Battery Anode”, Journal of Solid State Electrochemistry, vol. 23, pp. 513-518, 2019.[Abstract]


Here, we report reactive DC-sputter deposited Co 3 O 4 thin films as a promising and stable Li-ion battery anode. Thin films were deposited on stainless steel by reactive sputtering of cobalt target in O 2 atmosphere. X-ray diffraction and X-ray photo electron spectroscopy confirm the formation of Co 3 O 4 crystal structure and absence of other impurities. The electron microscopy analysis shows a columnar growth morphology of the thin films while high resolution images reveal that the film is composed of ultra-small nanoparticles of average size of 5 nm. Fabricated half cells upon cycling between 3.0 and 0.01 V exhibit a stable capacity of 1125 mAh/g at a current density of 1 A/g for 100 cycles. Moreover, the electrode exhibited excellent rate capability and stability at higher rates; at current density of 10 A/g, a capacity close to 1000 mAh/g was observed. The excellent cycling stability of the cell was further confirmed by cycling at a high rate of 25 A/g (28 C) wherein the same was able to retain a capacity of 330 mAh/g even at the end of 1800 cycles. This enhanced performance could be related to the formation of 5-nm primary particles and columnar growth morphology, capable of reducing the lithium ion diffusion lengths and thus offered better kinetics even at high rates.

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2019

B. Gangaja, Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Surface-Engineered Li 4 Ti 5 O 12 Nanoparticles by TiO2 Coating for Superior Rate Capability and Electrochemical Stability at Elevated Temperature”, Applied Surface Science, vol. 480, pp. 817-821, 2019.[Abstract]


Lithium ion batteries are dominating the energy storage market owing to its capability in powering portable electronics to electric vehicles. However, the power capabilities of these batteries are still relatively low limiting their applications in fast charging. In this paper, we report a strategy in elevating the rate capability of lithium titanate (Li 4 Ti 5 O 12 - LTO), one of the safest anode materials known. We demonstrate that a simple chemical method of coating titania (TiO 2 ) on lithium titanate nanoparticles followed by low temperature annealing yields a superior anode to bare-LTO. The surface coated electrode exhibits high discharge capacity of 212 mAh/g at 10C rate while the bare-LTO deliver only 138 mAh/g. Likewise, the surface engineered electrode displays excellent ultra-high rate capability (150C) and long cycling stability of 1000 cycles (at 60C rate). Impedance spectroscopy results confirm that the charge transfer resistance in surface engineered sample (CS-3) is comparatively lower than the bare-LTO electrode. Ex situ TEM investigation shows that the titania inhibits surface phase transition when cycled at elevated temperature which could be advantageous as it is a manifestation of minimal gassing in the batteries.

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2018

Dr. Dhamodaran Santhanagopalan, Benny, M., Binitha, G., and Shantikumar V Nair, “Long Cycle-life and High Rate Capability of Electrosprayed NiCo2O4 Nanoparticles as Li-ion Battery Anode”, Ionics, 2018.

2018

B. Gangaja, Muralidharan, H. P., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Ultra long (10K) Cycle-Life and High-Power Li-Ion Storage in Li4Ti5O12 Films Developed via Sustainable Electrophoretic Deposition Process”, ACS Sustainable Chemistry and Engineering, vol. 6, pp. 4705-4710, 2018.

2018

B. Gangaja, Haridas, A. K., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Spray Pyrolysis-Deposited TiO2 Thin Films as High-Performance Lithium ion Battery Anodes”, Ionics, 2018.[Abstract]


Focusing on additive-free electrodes, thin films are of typical interest as electrodes for lithium ion battery application. Herein, we
report the fabrication of TiO2 thin films by spray pyrolysis deposition technique. X-ray diffraction and transmission electron
microscopic analysis confirms the formation of anatase TiO2. Electrochemical evaluation of these sub-micron TiO2 thin films
exhibits high-rate performance and long cycling stability. At 1C rate (1C = 335 mA/g), the electrode delivered discharge capacity
of 247 mAh/g allowing about 0.74 lithium into the structure. The electrodes also delivered specific capacities of 122 and 72 mAh/
g at 10 and 30C rates, respectively. Without conductive additives, this excellent performance can be attributed to the nanosize
effect of TiO2 particles combined with the uniform porous architecture of the electrode. Upon cycling at high rates (10 and 30C),
the electrode exhibited excellent cycling stability and retention, specifically only < 0.6% capacity loss per cycle over 2500 cycles.

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2018

J. Z. Lee, Wynn, T. A., Meng, Y. S., and Dr. Dhamodaran Santhanagopalan, “Focused ion beam fabrication of LiPON-based solid-state lithium-ion nanobatteries for in situ testing”, Journal of Visualized Experiments, vol. 2018, 2018.[Abstract]


Solid-state electrolytes are a promising replacement for current organic liquid electrolytes, enabling higher energy densities and improved safety of lithium-ion (Li-ion) batteries. However, a number of setbacks prevent their integration into commercial devices. The main limiting factor is due to nanoscale phenomena occurring at the electrode/electrolyte interfaces, ultimately leading to degradation of battery operation. These key problems are highly challenging to observe and characterize as these batteries contain multiple buried interfaces. One approach for direct observation of interfacial phenomena in thin film batteries is through the fabrication of electrochemically active nanobatteries by a focused ion beam (FIB). As such, a reliable technique to fabricate nanobatteries was developed and demonstrated in recent work. Herein, a detailed protocol with a step-by-step process is presented to enable the reproduction of this nanobattery fabrication process. In particular, this technique was applied to a thin film battery consisting of LiCoO2/LiPON/a-Si, and has further been previously demonstrated by in situ cycling within a transmission electron microscope. © 2018, Journal of Visualized Experiments.

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2018

S. S. Jayasree, Nair, S., and Dr. Dhamodaran Santhanagopalan, “Ultrathin TiO2 Coating on LiCoO2 for Improved Electrochemical Performance as Li–Ion Battery Cathode”, ChemistrySelect, vol. 3, pp. 2763-2766, 2018.[Abstract]


Surface modification of LiCoO2 (LCO) gained much attention as it could play a prominent role in improving electrochemical performance and structural stability. Herein, we report an ultra-thin TiO2 coating on LiCoO2 (LCO-TiO2) as a potential candidate to overcome the electrochemical, structural instability and interface issues of the bare-LCO. The structural properties as well as electrochemical performances of bare-LCO and LCO-TiO2 were investigated by X-Ray diffraction, Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Galvanostatic charge-discharge and electrochemical impedance spectroscopy (EIS). At the end of 100 cycles, 1C rate capacity retention was about 50% and 90% for bare-LCO and LCO-TiO2 respectively. Rate studies showed that the bare LCO exhibited a specific capacity of ∼120 mAh/g and only 16 mAh/g at 1C and 60 discharge rates respectively whereas, the TiO2 coated LCO showed a capacity of ∼132 mAh/g and nearly 98 mAh/g at 1C and 60C discharge rates respectively. The implementation of TiO2 coating over LiCoO2 enhanced the electrochemical performance, cell stability as well as efficiency. © 2018 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim

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2018

B. Gangaja, Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Interface-Engineered LiTiO-TiO Dual-Phase Nanoparticles and CNT Additive for Supercapacitor-Like High-Power Li-ion Battery Applications”, Nanotechnology, vol. 29, no. 9, p. 095402, 2018.[Abstract]


The single-pot synthesis of dual-phase spinel-LiTiO and anatase-TiO (LTO-TiO) nanoparticles over all the phase fractions ranging from pure LTO to pure TiO is conducted. Carrying out the process over the complete range enabled the identification of a unique weight ratio of 85:15 (LTO:TiO), providing the best combination of capacity, rate capability and cycling stability. We show that for this composition dual-phase nanoparticles have a predominant interfacial orientation of (111)∣∣(004) , while it is (111)∣∣(101) for other compositions. This study therefore shows that the dual-phase interface with these specific orientations gives the best performance. The synergistic combination of dual-phase nanoparticles with multi-wall carbon nanotubes improves the performance further. This results in an electrode with supercapacitor-like rate capability delivering high discharge capacities of 174, 127, 119, 110, 101 and 91 mAh g at specific currents of 2000, 6000, 12 000, 18 000, 24 000 and 30 000 mA g, respectively. A discharge capacity of 174 mAh g at a specific current of 2000 mA g with only 0.005% capacity loss per cycle over 3000 cycles is demonstrated. At current densities of 6000, 12 000 and 24 000 mA g, stable cycling is obtained for 1500 cycles. The present work enables nano-engineered interfaces in LTO-TiO dual-phase nanoparticles with an electrochemical performance that is better than its individual components, opening up the potential for high-power Li-ion battery applications.

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2017

B. Gangaja, Reddy, K. Siva, Nair, S., and Dr. Dhamodaran Santhanagopalan, “Impact of Carbon Nanostructures as Additives with Spinel Li4Ti5O12/LiMn2O4 Electrodes for Lithium Ion Battery Technology”, ChemistrySelect, vol. 2, pp. 9772-9776, 2017.[Abstract]


Abstract Spinel structured nanomaterials have shown good stability for lithium ion storage applications. Among all, Li4Ti5O12 (LTO) anode and LiMn2O4 (LMO) cathode is a potential combination for high energy and high power applications. In the present work, we utilize this specific combination to fabricate full-cells in combination with carbon nanostructures as additives. Typically, 20–25 nm sized LTO and 200–500 nm sized LMO nanoparticle electrodes are composited with carbon nanostructures including, carbon nanotube (CNT), carbon black (CB) and graphene nanoplatelets (GNP). High rate performance of respective half-cells (lithium metal as counter electrode) of LTO and LMO are tested up to 50C. It was found that half-cells with CNT additive retained almost 80% of its 1C rate capacity at 50C rate. Also both the electrodes exhibited 1000 cycles stability with retention of about 80% at 10C rate cycling. Using these CNT additive based electrodes, a full-cell fabricated and tested exhibited high capacity and stable cycling over 500 cycles at 1000 mA/g specific current. The full-cell delivered power density of about 2310 W/kg and energy density of about 140 Wh/kg that can be further improved for high power Li-ion battery technology.

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2017

S. Reddy Kasireddy, Gangaja, B., Shantikumar V Nair, and Dr. Dhamodaran Santhanagopalan, “Mn4+ Rich Surface Enabled Elevated Temperature and Full-cell Cycling Performance of LiMn2O4 Cathode Material”, Electrochimica Acta, vol. 250, pp. 359 - 367, 2017.[Abstract]


LiMn2O4 (LMO) cathode exhibiting improved electrochemical performance is reported. X-ray diffraction confirms spinel cubic structure in the bulk with localized structural integrity confirmed by high-resolution Transmission Electron Microscopy (TEM) analysis showing lattice fringes with spacing of 0.48nm corresponding to (111) of spinel LMO. X-ray photoelectron spectroscopy (XPS) study quantified the Mn4+/Mn3+∼2 instead of 1 on the surface of pristine LMO nanoparticles. Mn4+ rich surface improved elevated temperature cycling stability inhibiting Mn-dissolution. The surface rich Mn4+ and almost equal concentration of Mn4+ and Mn3+ in the sub-surface/bulk was confirmed by XPS analysis upon ion-etching. At room temperature, high discharge capacity of ∼110 mAh/g at 2C rate and ∼102 mAh/g at 10C rate is reported for long cycles (over 500). Cycling at 55°C, capacity retention of 81.2% and 72% at the end of 200 cycles for 1C and 10C discharge rates respectively are testified for the electrochemical stability. This is superior elevated temperature performance of LMO electrodes especially, without any surface coating or doping. To demonstrate LMO cathode’s potential, a full-cell against Li4Ti5O12 and commercial graphite anodes were tested that exhibit discharge capacity of 95 mAh/g and 82 mAh/g respectively with retention of ∼82% over 100 cycles. Finally, electrodes after first charge and discharge have been investigated by ex situ XPS to correlate the oxidation states of manganese with pristine LMO.

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2017

A. Radhakrishnan, Gangaja, B., Nair, S., and Dr. Dhamodaran Santhanagopalan, “Reversible Cu4O3 Phase Formation in CuO Nanoplate Anodes for High Capacity and High Coulombic Efficiency”, ChemistrySelect, vol. 2, pp. 11548-11551, 2017.[Abstract]


Conversion materials with high specific capacity are of interest to improve energy density of Li-ion batteries. Here, we present results concerning hydrothermally synthesized CuO nanoplates that exhibit high specific capacity of 800 and 698 mAh/g at C/2 and 1C rates respectively and 180 mAh/g at a high rate of 30C. The electrodes exhibit high Coulombic efficiencies of about 66% and 60% at C/2 and 1C rate respectively, these are high efficiency values compared to the ones reported in the literature at respective rates. To understand the high performance, ex situ x-ray diffraction at different states of first discharge/charge is utilized that shine light on the lithiation/delithiation pathways of the CuO nanoplates. Lithiation proceeds through multiple phase transition CuO → Cu4O3 → Cu2O → Cu and it was found that Cu4O3 is reversible at the end of first charge. Cu and residual Cu2O was observed at the end of lithiation along with Li2O and Li2O2 phases. At the end of first charge, Cu4O3 phase along with CuO was observed as a major end-product with relatively minor concentrations of Cu2O. Cu4O3 as a major constituent observed in composite electrode seems to be the key information that can explain good reversibility and high Coulombic efficiency reported in the present work. © 2017 Wiley-VCH Verlag GmbH &amp; Co. KGaA, Weinheim

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2017

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 »»

2017

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

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

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 »»

2016

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 »»

2016

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

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.

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