Browsing by Author "Chandrasekaran, Nithya"

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BI2O3@REDUCED GRAPHENE OXIDE NANOCOMPOSITE: AN ANODE MATERIAL FOR SODIUM-ION STORAGE
(European Chemical Society Publishing, 2015-03-11) Chandrasekaran, Nithya
The high capacity, excellent cyclability, and good rate capability of reduced graphene oxide (rGO) anchored with a Bi2O3 nanocomposite for sodium-ion batteries are reported (see figure). This Bi2O3@rGO nanocomposite has the advantages of high reversible capacity with capacity retention (at high rate). Results suggest that anchoring rGO sheets with metal oxides is one of the simplest ways to enhance the electrochemical performance of sodium-ion batteries.The high capacity, excellent cyclability, and good rate capability of reduced graphene oxide (rGO) anchored with Bi2O3 nanocomposite for sodium-ion batteries is reported. A simple reduction method is adapted to deposit spherical Bi2O3 nanoparticles on the surface of rGO sheets. The surfactant cetyltrimethylammonium bromide (CTAB) plays a major role in controlling the morphology of the Bi2O3 nanoparticles. This Bi2O3@rGO nanocomposite has the advantages of high reversible capacity with a capacity retention (at high rate) of 70.2 % after 200 cycles at a current density of 350 mA g−1. This superior performance can be attributed to the fact that rGO sheets hamper the volume expansion of Bi2O3 nanoparticles and result in faster diffusion of Na+ ions (diffusion coefficient: 5.12×10−8 cm2 s−1) and smaller internal resistance (84.17 Ω) compared with pristine Bi2O3 nanoparticles. The results suggest that anchoring rGO sheets with metal oxides is one of the simplest ways to enhance the electrochemical performance of sodium-ion batteries.
BI2S3 NANORODS DEPOSITED ON REDUCED GRAPHENE OXIDE FOR POTASSIUM-ION BATTERIES
(ACS Publications, 2023-03-21) Chandrasekaran, Nithya; Jeevan Kumar, Reddy Modigunta; Insik, In; Soye, Kim; Sukumaran, Gopukumar
Hierarchical nanocomposites with surface active bonding features serve as an efficient electrode material for high-performance Li-/Na-/K-ion batteries. Tuning the physiochemical properties of these hierarchical nanocomposites has a great impact on the extremely improved electrochemical performance, and it is attributed to the synergistic effect of heterogeneous components. Herein, we report a hydrothermally synthesized bismuth sulfide (Bi2S3) nanorod bonding on the surface of the reduced graphene oxide (rGO) matrix and investigate it as an anode material for potassium-ion batteries. This hierarchical nanocomposite anode exhibits a high initial reversible capacity (586 mA h g–1 at 100 mA g–1), long-term cycling stability (410 mA h g–1 after 1000 cycles, 70% capacity retention), and an outstanding rate capability (140 mA h g–1 at 3 A g–1). This excellent electrochemical performance of the Bi2S3/rGO nanocomposite is attributed to the presence of active sites in rGO nanosheets that not only enhances the electrical conductivity of Bi2S3 nanorods but also prevents the shuttle effect of polysulfide through the formation of the in-built C–S bond, which is confirmed by X-ray photoelectron spectroscopy. Through the ex-situ X-ray diffraction patterns analysis at different voltage regions, a phase transformation mechanism has been proposed for K-ion storage in Bi2S3 nanorods. An ex-situ high-resolution transmission electron microscopy analysis reveals the structural and morphological stability of Bi2S3 nanorods. Further, the kinetic studies confirmed that the surface dominated pseudocapacitive K-ion storage also plays a major role in improving the electrochemical performance of the Bi2S3 nanorods/rGO nanocomposite. The K-ion full cell is successfully assembled, which exhibits stable cycling performance after 100 cycles at 1 C rate.
BI2S3 NANORODS DEPOSITED ON REDUCED GRAPHENE OXIDE FOR POTASSIUM-ION BATTERIES
(2023-03-21) Chandrasekaran, Nithya; Jeevan, Kumar Reddy Modigunta; Insik, In; Soye, Kim; Sukumaran, Gopukumar
Hierarchical nanocomposites with surface active bonding features serve as an efficient electrode material for high-performance Li-/Na-/K-ion batteries. Tuning the physiochemical properties of these hierarchical nanocomposites has a great impact on the extremely improved electrochemical performance, and it is attributed to the synergistic effect of heterogeneous components. Herein, we report a hydrothermally synthesized bismuth sulfide (Bi2S3) nanorod bonding on the surface of the reduced graphene oxide (rGO) matrix and investigate it as an anode material for potassium-ion batteries. This hierarchical nanocomposite anode exhibits a high initial reversible capacity (586 mA h g–1 at 100 mA g–1), long-term cycling stability (410 mA h g–1 after 1000 cycles, 70% capacity retention), and an outstanding rate capability (140 mA h g–1 at 3 A g–1). This excellent electrochemical performance of the Bi2S3/rGO nanocomposite is attributed to the presence of active sites in rGO nanosheets that not only enhances the electrical conductivity of Bi2S3 nanorods but also prevents the shuttle effect of polysulfide through the formation of the in-built C–S bond, which is confirmed by X-ray photoelectron spectroscopy. Through the ex-situ X-ray diffraction patterns analysis at different voltage regions, a phase transformation mechanism has been proposed for K-ion storage in Bi2S3 nanorods. An ex-situ high-resolution transmission electron microscopy analysis reveals the structural and morphological stability of Bi2S3 nanorods. Further, the kinetic studies confirmed that the surface dominated pseudocapacitive K-ion storage also plays a major role in improving the electrochemical performance of the Bi2S3 nanorods/rGO nanocomposite. The K-ion full cell is successfully assembled, which exhibits stable cycling performance after 100 cycles at 1 C rate.
CORRECTION: ELECTROCHEMICAL STUDIES ON CRYSTALLINE CUS AS AN ELECTRODE MATERIAL FOR NON-AQUEOUS NA-ION CAPACITORS
(Royal Society of Chemistry, 2021-03-11) Manoj, Goswami; Chandrasekaran, Nithya; Sathish, N; Satendra, Kumar; Netrapal, Singh; Srivastava, A K; Surender, Kumar
Correction for ‘Electrochemical studies on crystalline CuS as an electrode material for non-aqueous Na-ion capacitors
CORRECTION: ELECTROCHEMICAL STUDIES ON CRYSTALLINE CUS AS AN ELECTRODE MATERIAL FOR NON-AQUEOUS NA-ION CAPACITORS
(Royal Society of Chemistry, 2021-03-11) Manoj, Goswami; Chandrasekaran, Nithya; Sathish, N; Satendra, Kumar; Netrapal, Singh; Srivastava, A K; Surender, Kumar
Correction for ‘Electrochemical studies on crystalline CuS as an electrode material for non-aqueous Na-ion capacitors
DOPANT-FREE MAIN GROUP ELEMENTS SUPPORTED COVALENT ORGANIC–INORGANIC HYBRID CONDUCTING POLYMER FOR SODIUM-ION BATTERY APPLICATION
(ACS Publications, 2022-01-03) Seenuvasan, Vedachalam; Pandiaraj, Sekar; Chandrasekaran, Nithya; Nithya, Murugesh; Ramasamy, Karvembu
Organic–inorganic hybrid polymeric materials have shown potential applications in various fields. An approach to prepare a new class of a covalent organic–inorganic hybrid polymer (COIHP-1) using tris(2,3,6,7,10,11-hexahydroxytriphenylene) and inorganic heterocycle (hexachlorophosphazene) is developed. The design of COIHP-1 with porous nature has been an important goal as it can fulfill the demands of next-generation batteries and other electrochemical devices. COIHP-1 shows a high electrical conductivity of 9.52 × 10–3 S/cm. For the first time, COIHP-1 is employed as an anode material with maximum capacity in Na+ batteries, and it was characterized by various spectroscopic studies. It delivers a reversible capacity of 310 mAh g–1 at a current density of 0.035 A g–1, retains 65% of initial capacity after 500 cycles, and preserves the mesoporous nature even after prolonged cycling as proved by the post transmission electron microscopy (TEM) analysis. Moreover, COIHP-1 shows an excellent rate capability: it delivers 90 mAh g–1 even at a high current density of 3 A g–1. The enhanced Na+ storage capability, cycling stability, and rate capability are due to the mesoporous scaffold, which offers reversible accommodation for the ions. Mainly, the Na+ storage capability of COIHP-1 arises because of its polymeric −P═N− framework layer, which also provides hosting sites for the ions in the π-bond or lone pair of N. This work opens a door for developing a new kind of hybrid polymeric electrode material for rechargeable Na+ batteries.
DOPANT-FREE MAIN GROUP ELEMENTS SUPPORTED COVALENT ORGANIC–INORGANIC HYBRID CONDUCTING POLYMER FOR SODIUM-ION BATTERY APPLICATION
(ACS Publications, 2022-01-03) Seenuvasan, Vedachalam; Pandiaraj, Sekar; Chandrasekaran, Nithya; Nithya, Murugesh; Ramasamy, Karvembu
Organic–inorganic hybrid polymeric materials have shown potential applications in various fields. An approach to prepare a new class of a covalent organic–inorganic hybrid polymer (COIHP-1) using tris(2,3,6,7,10,11-hexahydroxytriphenylene) and inorganic heterocycle (hexachlorophosphazene) is developed. The design of COIHP-1 with porous nature has been an important goal as it can fulfill the demands of next-generation batteries and other electrochemical devices. COIHP-1 shows a high electrical conductivity of 9.52 × 10–3 S/cm. For the first time, COIHP-1 is employed as an anode material with maximum capacity in Na+ batteries, and it was characterized by various spectroscopic studies. It delivers a reversible capacity of 310 mAh g–1 at a current density of 0.035 A g–1, retains 65% of initial capacity after 500 cycles, and preserves the mesoporous nature even after prolonged cycling as proved by the post transmission electron microscopy (TEM) analysis. Moreover, COIHP-1 shows an excellent rate capability: it delivers 90 mAh g–1 even at a high current density of 3 A g–1. The enhanced Na+ storage capability, cycling stability, and rate capability are due to the mesoporous scaffold, which offers reversible accommodation for the ions. Mainly, the Na+ storage capability of COIHP-1 arises because of its polymeric −P═N− framework layer, which also provides hosting sites for the ions in the π-bond or lone pair of N. This work opens a door for developing a new kind of hybrid polymeric electrode material for rechargeable Na+ batteries.
ELECTROCHEMICAL STUDIES ON CRYSTALLINE CUS AS AN ELECTRODE MATERIAL FOR NON-AQUEOUS NA-ION CAPACITORS
(Royal Society of Chemistry, 2020-03-03) Manoj, Goswami; Chandrasekaran, Nithya; Sathish, N; Satendra, Kumar; Netrapal, Singh; A K, Srivastava; Surender, Kumar
Current investigations are concentrated on the development of high-performance electrode materials for sodium-ion capacitors (NICs). Copper sulphide can be employed as an electrode material for sodium-ion capacitors owing to its electrical conductivity and specific capacity. Crystalline CuS provides a large surface area for Na insertion/extraction. In this context, we have reported CuS powder synthesised via a simple wet chemical route. XRD and FT-IR studies have been carried out to determine the phase formation and confirm the purity of the CuS powder. A specific surface area of 62 m2 g−1 is measured by a BET surface area analyser. NICs were assembled in a non-aqueous medium with CuS particles and investigated for charge–discharge cycling in the potential window from 0.01 to 3 V. Cyclic voltammetry (CV) confirmed that at a high scan rate from 10 mV s−1 to 100 mV s−1, the CuS particles showed ideal capacitive behaviour. The calculated value of specific capacitance was 160 F g−1 for the CuS particles. At a scan rate of 1 mV s−1, 74.8% capacitive contribution was obtained from the CuS particles. Electrochemical impedance spectroscopy (EIS) revealed the interfacial interactions of the CuS particles with an Na-based electrolyte.
HETEROSTRUCTURE OF TWO DIFFERENT 2D MATERIALS BASED ON MOS2 NANOFLOWERS@RGO: AN ELECTRODE MATERIAL FOR SODIUM-ION CAPACITORS
(Royal Society of Chemistry, 2018-09-05) Kiruthiga, Ramakrishnan; Chandrasekaran, Nithya; Ramasamy, Karvembu
Sodium ion capacitors are under extensive investigation as companionable pre-existing lithium ion batteries and sodium ion batteries. Finding a suitable host for sodium ion storage is still a major challenge. In this context, here we report a MoS2 nanoflowers@rGO composite produced via a hydrothermal method followed by an ultra sonication process as a sodium ion symmetric hybrid supercapacitor. The structural and electrochemical performances of the electrode material were investigated to establish its applicability in sodium ion capacitors. The electrochemical performance was evaluated using metallic sodium in a half cell configuration which delivered a maximum specific capacitance of 226 F g−1 at 0.03 A g−1. When examined as a symmetric hybrid electrode (full cell) it delivered a maximum capacitance of 55 F g−1 at 0.03 A g−1. This combination may be a new gateway for upcoming research work which deals with sodium ion storage applications. The results confirmed that the as-synthesized MoS2 nanoflowers@rGO heterostructure electrode exhibited notable electrochemical behaviour.
HIGH-PERFORMING LIMGXCUYCO1−X−YO2 CATHODE MATERIAL FOR LITHIUM RECHARGEABLE BATTERIES
(American Chemical Society, 2012-08-22) Chandrasekaran, Nithya; Ramasamy, Thirunakaran; Arumugam, Sivashanmugam; Sukumaran, Gopukumar
Sustainable power requirements of multifarious portable electronic applications demand the development of high energy and high power density cathode materials for lithium ion batteries. This paper reports a method for rapid synthesis of a cobalt based layered cathode material doped with mixed dopants Cu and Mg. The cathode material exhibits ordered layered structure and delivers discharge capacity of ∼200 mA h g–1 at 0.2C rate with high capacity retention of 88% over the investigated 100 cycles.
INFLUENCE OF GA2O3, CUGA2O4 AND CU4O3 PHASES ON THE SODIUM-ION STORAGE BEHAVIOUR OF CUO AND ITS GALLIUM COMPOSITES
(Royal Society of Chemistry, 2020-02-14) Rekha, Pilliadugula; Chandrasekaran, Nithya; Gopala Krishnan, N
CuO and its gallium composites with various compositions are successfully fabricated by using a hydrothermal technique followed by calcination at 900 °C. The added Ga precursors formed oxides in the composites, such as Ga2O3, CuGa2O4 and Cu4O3, as confirmed through the X-ray diffraction patterns as well as the HRTEM and SAED patterns. Further HRTEM analysis also confirmed that Cu4O3 and CuGa2O4 phases reside on the surface of CuO in the composites with a CuO : Ga ratio of 90 : 10. The contents of various oxide phases varied when we increased the amount of Ga in the CuO composites. Changing the ratios of CuO and Ga precursors in the composites is quite effective in tailoring the sodium-ion storage behaviour of CuO. The resultant CuO/Ga composites exhibit remarkable electrochemical performance for sodium-ion batteries in terms of capacity, rate capability and cycling performance. The composite containing 90% CuO and 10% Cu/Ga oxides delivers the highest charge capacity of 661 mA h g−1 at a current density of 0.07 A g−1 with a capacity retention of 73.1% even after 500 cycles. The structure and morphology of the composite (90% CuO and 10% Cu/Ga oxides) was successfully retained after 500 cycles, which was confirmed through ex situ XRD, SEM and HRTEM analyses. The composite also exhibited remarkable rate capability in which it delivered 96 mA h g−1 even at a high current density of 6.6 A g−1. The enhanced electrochemical performances of CuO and its gallium composites are attributed to the presence of Cu4O3 and CuGa2O4 phases. The Cu4O3 phase is actively involved in the redox reaction and the CuGa2O4 phase stabilizes the CuO phase and buffers the volume expansion of CuO during cycling. The present approach eplores great opportunities for improving the electrochemical performance of oxide based anode materials for sodium-ion batteries.
INFLUENCE OF GA2O3, CUGA2O4 AND CU4O3 PHASES ON THE SODIUM-ION STORAGE BEHAVIOUR OF CUO AND ITS GALLIUM COMPOSITES
(Royal Society of Chemistry, 2020-03) Rekha, Pilliadugula; Chandrasekaran, Nithya; Gopala Krishnan, N
CuO and its gallium composites with various compositions are successfully fabricated by using a hydrothermal technique followed by calcination at 900 °C. The added Ga precursors formed oxides in the composites, such as Ga2O3, CuGa2O4 and Cu4O3, as confirmed through the X-ray diffraction patterns as well as the HRTEM and SAED patterns. Further HRTEM analysis also confirmed that Cu4O3 and CuGa2O4 phases reside on the surface of CuO in the composites with a CuO : Ga ratio of 90 : 10. The contents of various oxide phases varied when we increased the amount of Ga in the CuO composites. Changing the ratios of CuO and Ga precursors in the composites is quite effective in tailoring the sodium-ion storage behaviour of CuO. The resultant CuO/Ga composites exhibit remarkable electrochemical performance for sodium-ion batteries in terms of capacity, rate capability and cycling performance. The composite containing 90% CuO and 10% Cu/Ga oxides delivers the highest charge capacity of 661 mA h g-1 at a current density of 0.07 A g-1 with a capacity retention of 73.1% even after 500 cycles. The structure and morphology of the composite (90% CuO and 10% Cu/Ga oxides) was successfully retained after 500 cycles, which was confirmed through ex situ XRD, SEM and HRTEM analyses. The composite also exhibited remarkable rate capability in which it delivered 96 mA h g-1 even at a high current density of 6.6 A g-1. The enhanced electrochemical performances of CuO and its gallium composites are attributed to the presence of Cu4O3 and CuGa2O4 phases. The Cu4O3 phase is actively involved in the redox reaction and the CuGa2O4 phase stabilizes the CuO phase and buffers the volume expansion of CuO during cycling. The present approach eplores great opportunities for improving the electrochemical performance of oxide based anode materials for sodium-ion batteries.
INTRODUCTION TO NANOCARBON
(Springer Link, 2024-02-23) Shivaraj, Dhanushree; Chandrasekaran, Nithya
The field of nanomaterials has received much attention in recent years for its cutting-edge applications in areas such as energy, environmental, and life sciences. Owing to their distinct physio-chemical characteristics, nanocarbon with various dimensions such as 0D fullerenes and carbon-dots, 1D graphene nanoribbons and carbon nanotubes, 2D graphene oxides and graphene, and 3D nanodiamonds have gained a great deal of interest for applications in photovoltaics, optoelectronics, and electronics and as well as bio-imaging, sensing, and therapeutics. More interestingly graphene and CNTs offer unique structural properties like flexibility, mechanical stability, and electrical and thermal stability which create a revolution in the field of energy storage and sensing applications. This chapter systematically summarizes the synthesis of nanocarbons with distinct morphology and discusses how the synthesis methods influence the structural properties of nanocarbons. Further, the challenges in the synthesis methods and future perspectives of nanocarbons also discussed.
LICOXMN1-XPO4/C – A HIGH PERFORMING NANO COMPOSITE CATHODE MATERIAL FOR LITHIUM RECHARGEABLE BATTERIES
(WILEY‐VCH Verlag, 2012-12-01) Chandrasekaran, Nithya; Ramasamy, Thirunakaran; Arumugam, Sivashanmugam; Sukumaran, Gopukumar
Pristine and Co‐doped LiMnPO4 have been synthesized by the sol‐gel method using glycine as a chelating agent and the carbon composites were obtained by the wet ball mill method. The advantage of this method is that it does not require an inert atmosphere (economically viable) and facilitates a shorter time for synthesis. The LiCo0.09Mn0.91PO4/C nanocomposites exhibit the highest coulombic efficiency of 99 %, delivering a capacity of approximately 160 mAhg−1 and retain a capacity of 96.3 % over the investigated 50 cycles when cycled between 3–4.9 V at a charge/discharge rate of 0.1 C.
LICOXMN1-XPO4/C: A HIGH PERFORMING NANOCOMPOSITE CATHODE MATERIAL FOR LITHIUM RECHARGEABLE BATTERIES
(An Asian Journal, 2011-10-14) Chandrasekaran, Nithya; Ramasamy, Thirunakaran; Arumugam, Sivashanmugam; Sukumaran, Gopukumar
Pristine and Co-doped LiMnPO4 have been synthesized by the sol-gel method using glycine as a chelating agent and the carbon composites were obtained by the wet ball mill method. The advantage of this method is that it does not require an inert atmosphere (economically viable) and facilitates a shorter time for synthesis. The LiCo0.09Mn0.91PO4/C nanocomposites exhibit the highest coulombic efficiency of 99 %, delivering a capacity of approximately 160 mAhg−1 and retain a capacity of 96.3 % over the investigated 50 cycles when cycled between 3–4.9 V at a charge/discharge rate of 0.1 C.
A MN3O4 NANOSPHERES@RGO ARCHITECTURE WITH CAPACITIVE EFFECTS ON HIGH POTASSIUM STORAGE CAPABILITY
(Royal Society of Chemistry, 2019-09-10) Chandrasekaran, Nithya; Palanivelu, Vishnuprakash; Sukumaran, Gopukumar
A two dimensional (2D) Mn3O4@rGO architecture has been investigated as an anode material for potassium-ion secondary batteries. Herein, we report the synthesis of a Mn3O4@rGO nanocomposite and its potassium storage properties. The strong synergistic interaction between high surface area reduced graphene oxide (rGO) sheets and Mn3O4 nanospheres not only enhances the potassium storage capacity but also improves the reaction kinetics by offering an increased electrode/electrolyte contact area and consequently reduces the ion/electron transport resistance. Spherical Mn3O4 nanospheres with a size of 30–60 nm anchored on the surface of rGO sheets deliver a high potassium storage capacity of 802 mA h g−1 at a current density of 0.1 A g−1 along with superior rate capability even at 10 A g−1 (delivers 95 mA h g−1) and cycling stability. A reversible potassium storage capacity of 635 mA h g−1 is retained (90%) after 500 cycles even at a high current density of 0.5 A g−1. Moreover, the spherical Mn3O4@rGO architecture not only offers facile potassium ion diffusion into the bulk but also contributes surface K+ ion storage. The obtained results demonstrate that the 2D spherical Mn3O4@rGO nanocomposite is a promising anode architecture for high performance KIBs.
A MN3O4 NANOSPHERES@RGO ARCHITECTURE WITH CAPACITIVE EFFECTS ON HIGH POTASSIUM STORAGE CAPABILITY
(The Royal Society of Chemistry, 2019-11) Chandrasekaran, Nithya; Palanivelu, Vishnuprakash; Sukumaran, Gopukumar
A two dimensional (2D) Mn3O4@rGO architecture has been investigated as an anode material for potassium-ion secondary batteries. Herein, we report the synthesis of a Mn3O4@rGO nanocomposite and its potassium storage properties. The strong synergistic interaction between high surface area reduced graphene oxide (rGO) sheets and Mn3O4 nanospheres not only enhances the potassium storage capacity but also improves the reaction kinetics by offering an increased electrode/electrolyte contact area and consequently reduces the ion/electron transport resistance. Spherical Mn3O4 nanospheres with a size of 30-60 nm anchored on the surface of rGO sheets deliver a high potassium storage capacity of 802 mA h g-1 at a current density of 0.1 A g-1 along with superior rate capability even at 10 A g-1 (delivers 95 mA h g-1) and cycling stability. A reversible potassium storage capacity of 635 mA h g-1 is retained (90%) after 500 cycles even at a high current density of 0.5 A g-1. Moreover, the spherical Mn3O4@rGO architecture not only offers facile potassium ion diffusion into the bulk but also contributes surface K+ ion storage. The obtained results demonstrate that the 2D spherical Mn3O4@rGO nanocomposite is a promising anode architecture for high performance KIBs.
MORPHOLOGY ORIENTED CUS NANOSTRUCTURES: SUPERIOR K-ION STORAGE USING SURFACE ENHANCED PSEUDOCAPACITIVE EFFECTS
(Royal Society of Chemistry, 2020-04-28) Chandrasekaran, Nithya; Gowtham, Thiyagaraj
In this work, CuS nanostructures are successfully synthesized by using two different structure directing agents, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). For comparison CuS nanostructures are also synthesized without a structure directing agent. The morphologically dependent electrochemical properties such as the capacity, cycling stability, rate capability and capacitive controlled kinetics are comparatively investigated for potassium-ion batteries. The structure directing agents play a vital role in determining the surface area and electrochemical performance of the CuS nanostructures. The CTAB based CuS nanostructure shows a flake like morphology (length 100–150 nm and diameter 5–10 nm) whereas the SDS based CuS exhibits nanospheres with a particle size of 5–15 nm. The capacity, cycling stability and capacitive contribution are higher for the SDS assisted synthesis of the CuS based electrodes as compared to the CTAB assisted CuS and CuS without any agent. At a low current density of 0.1 A g−1, the SDS based CuS electrode exhibits an excellent reversible capacity of 470 mA h g−1. It also exhibits a stable reversible capacity of 451 mA h g−1 with a capacity retention of 73% after 500 cycles at a current density of 0.5 A g−1 (500 mA g−1). The excellent electrochemical performance of the SDS based CuS is attributed to its spherical morphology with a smaller particle size that exhibits a large surface area and the resulting surface dominated pseudocapacitive mechanism enhances the K+ ion storage. The comparative study of these CuS nanostructures can afford significant insights into the design of high performance potassium-ion batteries using hierarchical nanostructures with distinct morphologies.
MORPHOLOGY ORIENTED CUS NANOSTRUCTURES: SUPERIOR K-ION STORAGE USING SURFACE ENHANCED PSEUDOCAPACITIVE EFFECTS
(Royal Society of Chemistry, 2020-04-28) Chandrasekaran, Nithya; Gowtham, Thiyagaraj
In this work, CuS nanostructures are successfully synthesized by using two different structure directing agents, cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS). For comparison CuS nanostructures are also synthesized without a structure directing agent. The morphologically dependent electrochemical properties such as the capacity, cycling stability, rate capability and capacitive controlled kinetics are comparatively investigated for potassium-ion batteries. The structure directing agents play a vital role in determining the surface area and electrochemical performance of the CuS nanostructures. The CTAB based CuS nanostructure shows a flake like morphology (length 100–150 nm and diameter 5–10 nm) whereas the SDS based CuS exhibits nanospheres with a particle size of 5–15 nm. The capacity, cycling stability and capacitive contribution are higher for the SDS assisted synthesis of the CuS based electrodes as compared to the CTAB assisted CuS and CuS without any agent. At a low current density of 0.1 A g−1, the SDS based CuS electrode exhibits an excellent reversible capacity of 470 mA h g−1. It also exhibits a stable reversible capacity of 451 mA h g−1 with a capacity retention of 73% after 500 cycles at a current density of 0.5 A g−1 (500 mA g−1). The excellent electrochemical performance of the SDS based CuS is attributed to its spherical morphology with a smaller particle size that exhibits a large surface area and the resulting surface dominated pseudocapacitive mechanism enhances the K+ ion storage. The comparative study of these CuS nanostructures can afford significant insights into the design of high performance potassium-ion batteries using hierarchical nanostructures with distinct morphologies.
NOVEL LI4TI5O12/SN NANO-COMPOSITES AS ANODE MATERIAL FOR LITHIUM ION BATTERIES
(Elsevier, 2011-04) Arumugam, Sivashanmugam; Sukumaran, Gopukumar; Ramasamy, Thirunakaran; Chandrasekaran, Nithya; Shanmuga, Prema
Li4Ti5O12/Sn nano-composites have been prepared as anode material for lithium ion batteries by high-energy mechanical milling method. Structure of the samples has been characterized by X-ray diffraction (XRD), which reveals the formation of phase-pure materials. Scanning electron microscope (SEM) and transmission electron microscope (TEM) suggests that the primary particles are around 100 nm size. The local environment of the metal cations is confirmed by Fourier transform infrared (FT-IR) and the X-ray photoelectron spectroscopy (XPS) confirms that titanium is present in Ti4+ state. The electrochemical properties have been evaluated by galvanostatic charge/discharge studies. Li4Ti5O12/Sn–10% composite delivers stable and enhanced discharge capacity of 200 mAh g−1 indicates that the electrochemical performance of Li4Ti5O12/Sn nano-composites is associated with the size and distribution of the Sn particles in the Li4Ti5O12 matrix. The smaller the size and more homogeneous dispersion of Sn particles in the Li4Ti5O12 matrix exhibits better cycling performance of Li4Ti5O12/Sn composites as compared to bare Li4Ti5O12 and Sn particles. Further, Li4Ti5O12 provides a facile microstructure to fairly accommodate the volume expansion during the alloying and dealloying of Sn with lithium.