Biomass-derived porous carbon modified glass fiber separator as polysulfide reservoir for Li-S batteries

Selvan, Ramakrishnan Kalai,Zhu, Pei,Yan, Chaoi,Zhu, Jiadeng,Dirican, Mahmut,Shanmugavani, A.,Lee, Yun Sung,Zhang, Xiangwu Elsevier 2018 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.513 No.-

<P><B>Abstract</B></P> <P>Biomass-derived porous carbon has been considered as a promising sulfur host material for lithium-sulfur batteries because of its high conductive nature and large porosity. The present study explored biomass-derived porous carbon as polysulfide reservoir to modify the surface of glass fiber (GF) separator. Two different carbons were prepared from Oak Tree fruit shells by carbonization with and without KOH activation. The KOH activated porous carbon (AC) provides a much higher surface area (796 m<SUP>2</SUP> g<SUP>−1</SUP>) than pyrolized carbon (PC) (334 m<SUP>2</SUP> g<SUP>−1</SUP>). The <I>R</I> factor value, calculated from the X-ray diffraction pattern, revealed that the activated porous carbon contains more single-layer sheets with a lower degree of graphitization. Raman spectra also confirmed the presence of sp<SUP>3</SUP>-hybridized carbon in the activated carbon structure. The COH functional group was identified through X-ray photoelectron spectroscopy for the polysulfide capture. Simple and straightforward coating of biomass-derived porous carbon onto the GF separator led to an improved electrochemical performance in Li-S cells. The Li-S cell assembled with porous carbon modified GF separator (ACGF) demonstrated an initial capacity of 1324 mAh g<SUP>−1</SUP> at 0.2 C, which was 875 mAh g<SUP>−1</SUP> for uncoated GF separator (calculated based on the 2nd cycle). Charge transfer resistance (R<SUB>ct</SUB>) values further confirmed the high ionic conductivity nature of porous carbon modified separators. Overall, the biomass-derived activated porous carbon can be considered as a promising alternative material for the polysulfide inhibition in Li–S batteries.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Nitrogen-doped Multi-walled Carbon Nanotubes-MnCo₂O₄ microsphere as electrocatalyst for efficient oxygen reduction reaction

Yuvaraj, S.,Vignesh, A.,Shanmugam, S.,Kalai Selvan, R. Elsevier 2016 International journal of hydrogen energy Vol.41 No.34

<P><B>Abstract</B></P> <P>Nitrogen-doped Multi-walled Carbon Nanotubes (N-doped MWCNT)/MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid is synthesized by a facile hydrothermal method. The X-ray diffraction studies revealed the single phase formation of cubic spinel structured MnCo<SUB>2</SUB>O<SUB>4</SUB> and their composites. The presence of D and G band of MWCNT is identified through Raman spectral analysis. The elemental oxidation state and nitrogen content is obtained using X-ray photoelectron spectroscopy, which elucidates that Co and Mn exists in multivalence state and the nitrogen functional groups are in pyrolytic and pyridinic-type. FE-SEM shows the microsphere formation of MnCo<SUB>2</SUB>O<SUB>4</SUB> and size exhibits in the range of 6–9 μm. The N-doped MWCNT/MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid catalyst exhibits an improved oxygen reduction electrocatalytic activity in an aqueous alkaline medium when compared with pristine MnCo<SUB>2</SUB>O<SUB>4</SUB>.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped MWCNT composite with MnCo<SUB>2</SUB>O<SUB>4</SUB> was prepared by single step hydrothermal method. </LI> <LI> The half-wave potentials of MWCNT-MnCo<SUB>2</SUB>O<SUB>4</SUB> is 30 mV higher than MWCNT and 150 mV higher than MnCo<SUB>2</SUB>O<SUB>4</SUB> catalyst. </LI> <LI> MWCNT-MnCo<SUB>2</SUB>O<SUB>4</SUB> hybrid exhibits an improved ORR activity in an aqueous alkaline medium compared to pristine samples. </LI> </UL> </P>

Preparation of starch-based porous carbon electrode and biopolymer electrolyte for all solid-state electric double layer capacitor

Kasturi, Palanisamy Rupa,Ramasamy, Harivignesh,Meyrick, Danielle,Sung Lee, Yun,Kalai Selvan, Ramakrishnan Elsevier 2019 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.554 No.-

<P><B>Abstract</B></P> <P>An ever-increasing demand for energy coupled with environmental pollution associated with conventional energy production continues to drive the search for alternative renewable energy storage solutions. In this regard, a high surface area (1841 m<SUP>2</SUP> g<SUP>−1</SUP>), hierarchically porous (∼1.18 cm<SUP>3</SUP> g<SUP>−1</SUP>) and self-inherited nitrogen (2.1 at.wt%) based activated carbon are obtained from <I>Artocarpus heterophyllus</I> seed derived starch as a result of ZnCl<SUB>2</SUB> chemical activation. A flexible, conductive, thermally stable and bio-degradable biopolymer electrolyte film is prepared from <I>Manihot esculenta</I> starch powder. These eco-friendly hierarchically porous architectured carbon electrode and flexible biopolymer electrolytes are employed as significant components in a coin cell-based all-solid-state supercapacitor. The resulting device delivers a high specific capacitance of 240 Fg<SUP>−1</SUP> at 0.5 mA with 97% coulombic efficiency over 2000 cycles. In addition, the device provided excellent specific energy (17 Wh kg<SUP>−1</SUP>) and specific power (3823 W kg<SUP>−1</SUP>). Interestingly, the starch derived biopolymer electrolyte film, when buried under soil, shows a favourable natural rate of degradation. Therefore, this fabricated electric double layer capacitor can be used as a promising device with little to no potential environmental harm.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile hydrothermal synthesis of carbon-coated cobalt ferrite spherical nanoparticles as a potential negative electrode for flexible supercapattery

Sankar, Kalimuthu Vijaya,Shanmugapriya, Sathyanarayanan,Surendran, Subramani,Jun, Seong Chan,Selvan, Ramakrishnan Kalai Elsevier 2018 JOURNAL OF COLLOID AND INTERFACE SCIENCE - Vol.513 No.-

<P><B>Abstract</B></P> <P>Battery type electrodes would replace the currently available pseudocapacitive electrodes by the cause of high energy density and long discharge time. In this regard, battery type carbon coated CoFe<SUB>2</SUB>O<SUB>4</SUB> spherical nanoparticles is prepared by the facile hydrothermal method and tested as the possible negative electrode for supercapattery applications. The phase purity, electronic states of elements, and the presence of carbon is inferred through various sophisticated techniques. The calculated surface area of CoFe<SUB>2</SUB>O<SUB>4</SUB> and carbon coated CoFe<SUB>2</SUB>O<SUB>4</SUB> are found to be 9 and 26 m<SUP>2</SUP> g<SUP>−1</SUP>, respectively. The morphological analysis confirms the formation of uniform CoFe<SUB>2</SUB>O<SUB>4</SUB> nanospheres (∼25 nm) with a thin layer of carbon coating (∼2 nm). The amorphous carbon coating over CoFe<SUB>2</SUB>O<SUB>4</SUB> nanosphere is identified via high-resolution transmission electron microscope. The observed peak and plateau regions in the cyclic voltammogram and galvanostatic charge/discharge curves reveals the battery-type charge storage behaviour of the material. The carbon coated CoFe<SUB>2</SUB>O<SUB>4</SUB> delivers the maximum length capacitance of 9.9 F m<SUP>−1</SUP> at 1 mV s<SUP>−1</SUP> with a useful lifespan over 5000 cycles. The electrochemical impedance spectroscopy reveals that the carbon-coated CoFe<SUB>2</SUB>O<SUB>4</SUB> delivers the low charge transfer resistance than CoFe<SUB>2</SUB>O<SUB>4</SUB>. Further, the fabricated supercapattery provides the energy density of 160 × 10<SUP>−8</SUP> Wh cm<SUP>−1</SUP> at a power density of 67.2 μW cm<SUP>−1</SUP>. As well as, the device shows 93% of coulombic efficiency and 75% of the specific capacitance retention over 11,000 cycles. Overall, it is believed that the carbon-coated CoFe<SUB>2</SUB>O<SUB>4</SUB> can serve as a good candidate for flexible supercapatteries.</P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Facile synthesis of monodispersed 3D hierarchical Fe₃O₄ nanostructures decorated r-GO as the negative electrodes for Li-ion batteries

Kumar, S. Rajesh,Kim, Jong Guk,Viswanathan, C.,Kim, Won Bae,Selvan, R. Kalai,Ponpandian, N. Elsevier 2018 Materials research bulletin Vol.97 No.-

<P><B>Abstract</B></P> <P>One-pot solvothermal process is adopted to develop, 3D hierarchical Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles supported 2D reduced graphene oxide sheets (Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO) as possible negative electrodes for lithium ion batteries. The synthesis parameters are optimized to prepare agglomeration-free Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures with uniform size and shape on r-GO. The field emission scanning electron microscopic (FESEM) image reveals that the 3D hierarchical Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures are uniformly decorated on r-GO. The physicochemical and functional properties of Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO are systematically investigated using various techniques. The fabricated Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO electrode delivers an initial discharge capacity of 1221mAhg<SUP>−1</SUP> at a current density of 100mAg<SUP>−1</SUP> and retains the specific capacity of 1560mAhg<SUP>−1</SUP> after 100 cycles. Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO significantly enhances cyclic performance, when compared with bare Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles due to the uniform distribution of Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles on the graphene sheet with the more number of electrochemically active sites.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Monodispersed Fe<SUB>3</SUB>O<SUB>4</SUB> nanostructures with different shapes synthesized by solvothermal method. </LI> <LI> The fabricated Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO electrode delivers an initial discharge capacity of 1221mAhg<SUP>−1</SUP> at 100mAhg<SUP>−1</SUP>. </LI> <LI> Fe<SUB>3</SUB>O<SUB>4</SUB>/r-GO significantly enhances the cyclic stability and rate capability than bare Fe<SUB>3</SUB>O<SUB>4</SUB> nanoparticles </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrical and electrochemical properties of molten-salt-synthesized 0.05 mol Zr- and Si-doped Li4Ti5O12 microcrystals

Nithya, V. D.,Sharmila, S.,Vediappan, Kumaran,Lee, Chang Woo,Vasylechko, Leonid,Kalai Selvan, R. Springer-Verlag 2014 Journal of applied electrochemistry Vol.44 No.5

The first-principles study of CoSb₂O₄ and its electrochemical properties for supercapacitors

Shanmugavani, Amirthalingam,Lalitha, Murugan,Narayanan Kutty, Rajeesh Kumar,Vasylechko, Leonid,Lee, Yun Sung,Lakshmipathi, Senthilkumar,Kalai Selvan, Ramakrishnan Elsevier 2018 ELECTROCHIMICA ACTA Vol.283 No.-

<P><B>Abstract</B></P> <P>By varying Co:Sb molar ratio, crystalline CoSb<SUB>2</SUB>O<SUB>4</SUB> was synthesized through surfactant free hydrothermal method. The tetragonal crystal structure and phase composition of cobalt antimonate were obtained through XRD Rietveld refinement method. CoSb<SUB>2</SUB>O<SUB>4</SUB> exhibits a direct band gap of 2.89 eV was computed using First-principle density functional theory (DFT) calculations. Here, the Fermi energy level is upshifted to conduction band region, representing the n-type behaviour of the CoSb<SUB>2</SUB>O<SUB>4</SUB> unit cell. The oxidation state of +2 and + 3 of Co was identified through X-ray photoelectron spectroscopy analysis (XPS). Formation of submicron size, rod shape particles was confirmed by Transmission electron microscopic (TEM) images. Cyclic voltammogram exhibits a specific capacitance of 598 F g<SUP>−1</SUP> at 2 mV s<SUP>−1</SUP> in 1 M KOH. More importantly, Galvanostatic charge-discharge analysis (GCD) delivered the specific capacitance of 382 F g<SUP>−1</SUP> at 1 mA cm<SUP>−2</SUP>. For practical application, an asymmetric supercapacitor is constructed using Ni<SUB>3</SUB>(Fe(CN)<SUB>6</SUB>)<SUB>2</SUB>(H<SUB>2</SUB>O) as a positive electrode and synthesized one-dimensional CoSb<SUB>2</SUB>O<SUB>4</SUB> as a negative electrode, which offered a maximum specific capacitance of 279 Fg<SUP>-1</SUP> at 1 mV s<SUP>−1</SUP>. Cycling stability of the fabricated device demonstrated the retention of almost 100% and hence depicts its promising nature as an efficient electrode for supercapacitor application.</P>

Hydrothermally synthesised NiCoP nanostructures and electrospun N-doped carbon nanofiber as multifunctional potential electrode for hybrid water electrolyser and supercapatteries

Surendran, Subramani,Shanmugapriya, Sathyanarayanan,Zhu, Pei,Yan, Chaoyi,Vignesh, Ramasamy Hari,Lee, Yun Sung,Zhang, Xiangwu,Selvan, Ramakrishnan Kalai Elsevier 2019 ELECTROCHIMICA ACTA Vol.296 No.-

<P><B>Abstract</B></P> <P>In this work, a facile single-step hydrothermal technique is used to prepare a spherically concomitant foamy NiCoP as positrode for supercapatteries. Similarly, the nitrogen-doped carbon nanofibers are prepared by simple electrospinning technique to use as negatrode. The prepared materials are raptly examined through primary studies for both energy conversion and storage applications. Fascinatingly, NiCoP electrode encourages oxygen evolution reaction, and the carbon nanofiber electrode emboldens hydrogen evolution reaction with the minimum overpotential of 257 mV and 160 mV, respectively. In addition, a supercapattery is designed and operated at a full voltage window of 1.6 V using the fusion of carbon nanofiber as the negatrode and the cutting-edge NiCoP as the positrode, which presents a superior energy (56 Wh kg<SUP>−1</SUP>) and an improved power density (5333 W kg<SUP>−1</SUP>) with a long cyclic stability (5000 cycles). Finally, the fabricated supercapattery device is used to power the constructed hybrid water electrolyser that requisites a low cell voltage of 1.71 V to afford a current density of 10 mA cm<SUP>−2</SUP>. Overall, the prepared electrodes reveal its superiority of handling the multifunctional challenges for both water electrolyzer and supercapatteries.</P>