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Kang, Suk Hyun,Jo, Yong Nam,Prasanna, K.,Santhoshkumar, P.,Joe, Youn Cheol,Vediappan, Kumaran,Gnanamuthu, Ramasamy,Lee, Chang Woo Elsevier 2019 Journal of industrial and engineering chemistry Vol.71 No.-
<P><B>Abstract</B></P> <P>As a promising anode material, TiO<SUB>2−x</SUB> is prepared with a low bandgap by adding a zinc powder using a solvothermal reaction. It is homogeneous, spherical, and 30nm in size, changing from anatase to rutile. It shows a high discharge capacity, 253.8mAhg<SUP>−1</SUP>, after 50 cycles at 100mAg<SUP>−1</SUP> whereas the pristine TiO<SUB>2</SUB> material delivers mere 81.1mAhg<SUP>−1</SUP>. The improved electrochemical performance with cycling of the TiO<SUB>2−x</SUB> compared with the pristine TiO<SUB>2</SUB> material is attributed to the presence of Ti<SUP>3+</SUP> and/or oxygen vacancies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Bandgap tuned TiO<SUB>2−x</SUB> has been effectively prepared via a solvothermal reaction. </LI> <LI> Oxygen vacancy is successfully produced in TiO<SUB>2−x</SUB>. </LI> <LI> The prepared material exhibits excellent rate capability and specific capacity. </LI> <LI> Electronic conductivity and surface area are improved by oxygen vacancy. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Shaji, Nitheesha,Santhoshkumar, P.,Nanthagopal, Murugan,Senthil, Chenrayan,Lee, Chang Woo Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.491 No.-
<P><B>Abstract</B></P> <P>The performance of existing lithium-ion batteries (LIBs) is greatly hindered by the low specific capacity of graphite-based anodes (372 mAh g<SUP>−1</SUP>). Therefore, development of suitable anode materials that exhibit higher and stable capacity is necessary to improve performance. Transition metal oxides have attracted tremendous attention as next-generation anode materials for LIBs due to their high theoretical capacity. Herein, we report the synthesis of a porous CaFe<SUB>2</SUB>O<SUB>4</SUB> by a facile and time efficient solution combustion synthesis technique for use in an anode for LIBs. The as-prepared material exhibited improved electrochemical performance with specific discharge capacities of 441 mAh g<SUP>−1</SUP>, 518 mAh g<SUP>−1</SUP>, and 516 mAh g<SUP>−1</SUP> for the initial three cycles. It achieved stability with a deliverable specific discharge capacity of 551 mAh g<SUP>−1</SUP> after 150 cycles at a current density of 200 mA g<SUP>−1</SUP>. The porous CaFe<SUB>2</SUB>O<SUB>4</SUB> exhibits improved cyclic performance and rate capability. These improvements are attributed to the porous nature of active material and, more importantly, the presence of CaO, which effectively alleviates the volume changes by acting as a buffer matrix.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Porous CaFe<SUB>2</SUB>O<SUB>4</SUB> has been synthesized by a facile solution combustion synthesis technique. </LI> <LI> Mixed-metal oxides possessing electrochemically active-inactive constituents are reported. </LI> <LI> The porous CaFe<SUB>2</SUB>O<SUB>4</SUB> as an anode for LIBs exhibited improved electrochemical performances. </LI> <LI> The porous structure and the buffer matrices of CaO are owed for their improved activity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Santhoshkumar, P.,Prasanna, K.,Jo, Yong Nam,Sivagami, I. Nirmal,Kang, Suk Hyun,Lee, Chang Woo The Royal Society of Chemistry 2017 Journal of Materials Chemistry A Vol.5 No.32
<▼1><P>In the present work, we have synthesized zero-dimensional (0D) and three-dimensional (3D) iron oxide (α-Fe2O3) sub-micron particles using a one-pot hydrothermal approach.</P></▼1><▼2><P>In the present work, we have synthesized zero-dimensional (0D) and three-dimensional (3D) iron oxide (α-Fe2O3) sub-micron particles using a one-pot hydrothermal approach. Morphological studies reveal that the as-synthesized spherical α-Fe2O3 (SFO) material consists of nanospheres with void spaces. The prepared SFO delivers a high specific surface area of 100.80 m<SUP>2</SUP> g<SUP>−1</SUP> and significantly increases the contact area between the electrode and the electrolyte. The initial galvanostatic specific capacity of the SFO materials was 1306 mA h g<SUP>−1</SUP> at a current density of 100 mA g<SUP>−1</SUP>, which is superior to that of bare cubic α-Fe2O3 (CFO). Moreover, the mesoporous SFO shows a good cycling stability with a capacity retention rate of 91.4% after 100 cycles. These attractive results suggest that the mesoporous SFO shows a good electrochemical performance as a negative electrode material for high-performance Li-ion batteries.</P></▼2>
Sivagami, I. Nirmal,Prasanna, K.,Santhoshkumar, P.,Jo, Yong Nam,Kang, Suk Hyun,Kim, Tae Hong,Lee, Chang Woo American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.11
<P>A novel lithium transition metal orthosilicate compound, i.e., lithium zinc silicate (Li2ZnSiO4), is investigated as a potential cathode material for lithium ion batteries(LIBs). Li2ZnSiO4 is successfully synthesized via a facile sol-gel technique followed by a calcination step. The studied physical and electrochemical properties substantiate the Li2ZnSiO4 compound to be considered as a potential positive electrode in LIBs. The X-ray diffraction (XRD) results reveal an orthorhombic structure of Li2ZnSiO4 with sharp crystalline peaks. Field emission transmission electron microscopy (FE-TEM) images show a plate-like structure of a single particle with clear lattice fringes. The mapping results of FE-TEM along with X-ray photoelectron spectroscopy (XPS) confirm the chemical composition of Li2ZnSiO4 crystals. Field emission scanning electron microscopy (FE-SEM) further confirms the FE-TEM results on the morphology of Li2ZnSiO4 with a plate-like structure and an average particle size of 5 mu m. Electrochemical impedance spectroscopy (EIS) studies shows an initial charge transfer resistance (R-ct) of 371 Omega. An initial discharge capacity of 133 mAh g(-1) is obtained at the C/10 rate, which is comparable to other orthosilicate compounds.</P>
조용남,강석현,( P. Santhoshkumar ),조윤철,( S. K. S Saravana Karthikeyan ),이창우 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
One of promising advanced batteries is a Zn-air battery due to its high specific energy, low cost, high safety, and environmental friendliness. However, the Zn anodes in Zn-air batteries suffer from dendrite formation, shape change, corrosion, and hydrogen evolution reaction (HER). The dendrite formation and shape change could be improved by mechanical recharging system. However, the corrosion and HER are critical issues for both electrical and mechanical rechargeable Zn-air batteries. In this study, we have tried to modify the Zn anodes by alloy or coating for suppressing corrosion, HER, and self-discharge of the Zn-air batteries.
Kang, Suk Hyun,Jo, Yong Nam,Prasanna, K.,Kim, Tae Hong,Do, Su Jung,Santhoshkumar, P.,Sivagami, I. Nirmal,Lee, Chang Woo American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.11
<P>Herein, different amount of CuO are onto Li[Ni0.8Co0.1Mn0.1]O-2 (NCM811) cathode active materials and characterized using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), and field emission-transmission electron microscopy (FE-TEM). A 2 wt.% CuO-coated NCM811 material has an obviously enhanced electrochemical behavior compared with the NCM811 material. In addition, the 2 wt.% CuO-coated NCM811 has the highest capacity retention values of 82.4 and 63.9% in current density of 150 and 200 mA g(-1), respectively. The capacity retention of pristine NCM811 material is 84.1%, whereas that of 2 wt.% CuO-coated NCM811 material is 90.4% after 80 cycles at 60 degrees C. According to electrochemical impedance spectra (EIS), the film resistance and the charge transfer resistance of CuO-coated material are lower than those of pristine NCM811. The reason behind the enhanced electrochemical behaviors of CuO-coated material is that the CuO prevents a direct contact of the cathode active material with electrolyte, suppressing a side reaction between the cathode material and unwanted-byproduct hydrofluoric (HF) acid.</P>
P. Santhoshkumar,T. Subburaj,K. Karuppasamy,A. Kathalingam,Dhanasekaran Vikraman,박현창,김현석 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.104 No.-
Herein, a red iron oxide @ carbon fiber (RIO@CF) composite is prepared via a simple and effective singlehydrothermal and calcination process. The physico-chemical characteristics of as-prepared electrodeactive materials are examined by X-ray photoelectron spectroscopy, high resolution field emissionscanningelectron microscopy and field emission-tunneling electron microscopy analyses. When usedas the anode material in the Li-ion battery, as-prepared RIO@CF composite have shown a specific capacityof 1138 mAh g 1 after 150 cycles with a capacity retention of 86% at a current density of 100 mA g 1. Moreover, a specific capacity of 825 mAh g 1 is achieved in the first cycle at a current density of about5000 mA g 1. Thus, when compared to the pristine nano-cube-like red iron oxide (RIO) electrode material,the RIO@CF composite electrode exhibits an outstanding cyclic stability and rate capacity. This electrochemicalenhancement facilitates effective lithium ion transport into the RIO@CF composite electrode,thus improving the electrical conductivity. In addition, the application of a homogeneous carbon fibercoating can provide effective contact between the electrode surface and the electrolyte to further benefitthe electrochemical performance.
S.P. Ratnayake,C. Sandaruwan,M.M.M.G.P.G. Mantilaka,N. de Silva,D. Dahanayake,U.K Wanninayake,W.R.L.N. Bandara,S. Santhoshkumar,E. Murugan,G.A.J.Amaratunga,K.M. Nalin de Silva 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.95 No.-
A unique zirconia nanomorphology possessing an enhanced photocatalytic efficiency was developedutilizing a convenient single-sol synthesis process which involved in-situ doping of zirconia by boron. The boron-doped zirconia exhibited aflake morphology as opposed to the spherical pure form andsubsequent crystallographic investigations implied the phase conversion from binary to single-phasealong with the shape due to the doping. Optical characterization indicated a modified band structurewith newly generated isolated impurity states within the principle zirconia band edges. As per the X-rayspectroscopy data, boron was detected as chemically bound to oxygen while electron paramagneticresonance indicated the presence of an adsorbed oxygen lattice. During UV and simulated solarirradiation trials, respective removal capabilities of 90% and 93% of the model compound wereaccomplished, hence the effectiveness of the photocatalyst was confirmed. The enhanced photoactivityobserved in the UV region was attributed to combined effects of the boron-induced isolated impuritystates within principle band edges of zirconia, the defect-rich planer morphology, favorable interfacialinteractions and the greater availability of oxygen on the lattice. Developed nanoflakes are stable, inert,and efficient hence exhibiting compelling suitability in the remediation of harmful industrial organiccompounds.
조용남,P. Santhoshkumar,K. Prasanna,Kumaran Vediappan,이창우 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.76 No.-
The corrosion and hydrogen evolution reactions of Zn anodes accelerate the self-discharge of a Zn-airbattery. To suppress the corrosion reaction and improve the self-discharge behavior of a Zn-air battery,polyaniline (PANI) is synthesized with different amounts of 0.1 M sulfuric acid and coated on a Zn surface. The PANI-coated materials effectively suppress the corrosion reaction, and the Zn-air cells prepared withPANI-coated Zn materials exhibit enhanced self-discharge behavior. The specific discharge capacity after24 h storage and capacity retention of Zn were 520.2 mA h/g and 74.4%, respectively. Whereas the PANI-coated Zn (100 ml sulfuric acid) shows 565.3 mA h/g of specific discharge capacity after 24 h storage,75.8% corrosion inhibition efficiency and 96.9% capacity retention. Therefore, PANI-coated Zn materialsare effective in suppressing the corrosion reaction and improving self-discharge behaviors in Zn-airbatteries.