Adipic Acid Assisted Sol-Gel Synthesis of Li_1+x(Mn_0.4Ni_0.4Fe_0.2)_1-xO₂ (0 < x < 0.3) as Cathode Materials for Lithium Ion Batteries

Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Son, Ju-Nam,Kim, Shin-Ho,Kim, Min-Chul,Kim, Kwang-Jin,Lee, Sol-Nip,Lee, Yun-Sung Korean Chemical Society 2013 Bulletin of the Korean Chemical Society Vol.34 No.1

Layered $Li_{1+x}(Mn_{0.4}Ni_{0.4}Fe_{0.2})_{1-x}O_2$ (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with $R\bar{3}m$ space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M $LiPF_6$ in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, $Li_{1.2}(Mn_{0.32}Ni_{0.32}Fe_{0.16})O_2$ (x = 0.2)/$Li^+$ exhibits a good electrochemical property with maximum initial capacity of 160 $mAhg^{-1}$ between 2-4.5 V at 0.1 $mAcm^{-2}$ current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on $LiNiO_2-LiFeO_2-Li_2MnO_3$ has improved the properties of its end members.

Adipic Acid Assisted Sol-Gel Synthesis of Li1+x(Mn0.4Ni0.4Fe0.2)1-xO2 (0 < x < 0.3) as Cathode Materials for Lithium Ion Batteries

Kaliyappan Karthikeyan,Samuthirapandian Amaresh,Ju-Nam Son,Shin-Ho Kim,Min-Chul Kim,김광진,이윤성,Sol-Nip Lee 대한화학회 2013 Bulletin of the Korean Chemical Society Vol.34 No.1

Layered Li1+x(Mn0.4Ni0.4Fe0.2)1-xO2 (0 < x < 0.3) solid solutions were synthesized using solgel method with adipic acid as chelating agent. Structural and electrochemical properties of the prepared powders were examined by means of X-ray diffraction, Scanning electron microscopy and galvanostatic charge/discharge cycling. All powders had a phase-pure layered structure with R3m space group. The morphological studies confirmed that the size of the particles increased at higher x content. The charge-discharge profiles of the solid solution against lithium using 1 M LiPF6 in EC/DMC as electrolyte revealed that the discharge capacity increases with increasing lithium content at the 3a sites. Among the cells, Li1.2(Mn0.32Ni0.32Fe0.16)O2 (x = 0.2)/ Li+ exhibits a good electrochemical property with maximum initial capacity of 160 mAhg−1 between 2-4.5 V at 0.1 mAcm−2 current density and the capacity retention after 25 cycles was 92%. Whereas, the cell fabricated with x = 0.3 sample showed continuous capacity fading due to the formation of spinel like structure during the subsequent cycling. The preparation of solid solutions based on LiNiO2-LiFeO2-Li2MnO3 has improved the properties of its end members.

High-power lithium-ion capacitor using LiMnBO3 -nanobead anode and polyaniline-nanofiber cathode with excellent cycle life.

Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Lee, Sol-Nip,An, Jae-Yeon,Lee, Yun-Sung Wiley-VCH 2014 ChemSusChem Vol.7 No.8

<P>LiMnBO3 nanobeads (LMB-NB) with uniform size and distribution were synthesized using a urea-assisted microwave/solvothermal method. The potential application of LMB-NBs as an anode for a lithium-ion hybrid capacitor (Li-AHC) was tested with a polyaniline-nanofiber (PANI-NF) cathode in a nonaqueous LiPF6 (1?M)-ethylene carbonate/dimethyl carbonate electrolyte. Cyclic voltammetry (CV) and charge-discharge (C/DC) studies revealed that the PANI-NF/LMB-NB cell showed an exceptional capacitance behavior between 0-3 V along with a prolonged cycle life. A discharge capacitance of about 125 F g(-1) , and energy and power densities of about 42 Wh kg(-1) and 1500 W kg(-1) , respectively, could be obtained at a current density of 1 A g(-1) ; those Li-AHC values are higher relative to cells containing various lithium intercalation materials in nonaqueous electrolytes. In addition, the PANI-NF/LMB-NB cell also had an outstanding rate performance with a capacitance of 54 F g(-1) and a power density of 3250 W kg(-1) at a current density of 2.25 A g(-1) and maintained 94% of its initial value after 30000 cycles. This improved capacitive performance with an excellent electrochemical stability could be the result of the morphological features and inherent conductive nature of the electroactive species.</P>

Construction of high-energy-density supercapacitors from pine-cone-derived high-surface-area carbons.

Karthikeyan, Kaliyappan,Amaresh, Samuthirapandiyan,Lee, Sol Nip,Sun, Xueliang,Aravindan, Vanchiappan,Lee, Young-Gi,Lee, Yun Sung Wiley-VCH 2014 ChemSusChem Vol.7 No.5

<P>Very high surface area activated carbons (AC) are synthesized from pine cone petals by a chemical activation process and subsequently evaluated as an electrode material for supercapacitor applications in a nonaqueous medium. The maximum specific surface area of 3950?m(2) ?g(-1) is noted for the material treated with a 1:5 ratio of KOH to pine cone petals (PCC5), which is much higher than that reported for carbonaceous materials derived from various other biomass precursors. A symmetric supercapacitor is fabricated with PCC5 electrodes, and the results showed enhanced supercapacitive behavior with the highest energy density of 61?Wh?kg(-1). Furthermore, outstanding cycling ability is evidenced for such a configuration, and 90?% of the initial specific capacitance after 20,000?cycles under harsh conditions was observed. This result revealed that the pine-cone-derived high-surface-area AC can be used effectively as a promising electrode material to construct high-energy-density supercapacitors.</P>

Fluorine-doped Fe(2)O(3) as high energy density electroactive material for hybrid supercapacitor applications.

Karthikeyan, Kaliyappan,Amaresh, Samuthirapandian,Lee, Sol Nip,Aravindan, Vanchiappan,Lee, Yun Sung Wiley-VCH 2014 Chemistry - An Asian Journal Vol.9 No.3

<P>Nanostructured α-Fe2 O3 with and without fluorine substitution were successfully obtained by a green route, that is, microwave irradiation. The hematite phase materials were evaluated as a high-performance electrode material in a hybrid supercapacitor configuration along with activated carbon (AC). The presence of fluorine was confirmed through X-ray photoelectron spectroscopy and transmission electron microscopy. Fluorine-doped Fe2 O3 (F-Fe2 O3 ) exhibits an enhanced pseudocapacitive performance compared to that of the bare hematite phase. The F-Fe2 O3 /AC cell delivered a specific capacitance of 71?F?g(-1) at a current density of 2.25?A?g(-1) and retained approximately 90?% of its initial capacitance after 15?000?cycles. Furthermore, the F-Fe2 O3 /AC cell showed a very high energy density of about 28?W?h?kg(-1) compared to bare hematite phase (9?W?h?kg(-1) ). These data clearly reveal that the electrochemical performance of Fe2 O3 can be improved by fluorine doping, thereby dramatically improving the energy density of the system.</P>

All-Organic Sodium Hybrid Capacitor: A New, High-Energy, High-Power Energy Storage System Bridging Batteries and Capacitors

Thangavel, Ranjith,Kaliyappan, Karthikeyan,Kim, Dae-Ung,Sun, Xueliang,Lee, Yun-Sung American Chemical Society 2017 Chemistry of materials Vol.29 No.17

<P>The development of hybrid capacitors (HCs) has become essential for meeting the rising demand for devices that simultaneously deliver high energy with high power. Although the challenge to develop high-performance HCs remains great, it is also simultaneously essential to develop an eco-friendly and cleaner energy storage system for sustainable future use. To date, hybrid capacitors utilize heavily toxic inorganic insertion electrodes and hazardous coke-derived porous carbon adsorption electrodes to host ions. Herein, we present a conceptually novel all-organic sodium hybrid capacitor (OHC), rationally designed by replacing the conventional electrodes with clean, green, and metal free organic molecules, to host ions. A high energy density of similar to 95 Wh kg(-1) and an ultrahigh power density of 7 kW kg(-1) (based on active mass in both electrodes) are achieved with a low energy loss of similar to 0.22% per 100 cycles (similar to 89% retention after 5000 cycles), outperforming conventional HCs. The outstanding energy-power behavior of OHC bridges the performance gap between batteries and capacitors. This research holds great promise for the development of next-generation eco-friendly, clean, green, and safer high-energy, high-power devices.</P>

High performance organic sodium-ion hybrid capacitors based on nano-structured disodium rhodizonate rivaling inorganic hybrid capacitors

Thangavel, Ranjith,Ponraj, Rubha,Kannan, Aravindaraj G.,Kaliyappan, Karthikeyan,Kim, Dong Won,Chen, Zhongwei,Lee, Yun-Sung The Royal Society of Chemistry 2018 Green Chemistry Vol.20 No.21

<P>Sodium hybrid capacitors (NHCs) have tremendous potential to meet the simultaneous high energy-high power requirement of next-generation storage applications. But NHCs still face some obstacles due to poor sodium ion kinetics, low power, and poor cyclability while working with several inorganic sodium ion hosts. Additionally, developing high-performance NHCs that are sustainable and versatile is more crucial from the perspective of energy storage devices. Here, we report a conceptually new and high performance organic sodium hybrid capacitor (ONHC) system, developed by substituting a conventional toxic-metal-containing inorganic battery electrode of an NHC with a nano-structured, metal free, and renewable organic molecule - disodium rhodizonate - to host sodium ions. The sustainability of the ONHC is greatly enhanced by the simultaneous utilization of high surface area cardamom shell (as biomass)-derived porous carbon as a high-power capacitor electrode. The new system exhibits an outstanding performance, delivering a high energy density of ∼87 W h kg<SUP>−1</SUP> along with a high specific power of 10 kW kg<SUP>−1</SUP> (based on the mass in both electrodes), outperforming inorganic sodium hosts. High durability over 10 000 cycles (∼85% retention) with an ultra-low energy loss of ∼0.15% per 100 cycles is also demonstrated, indicating its emergence as a rival to conventional metal containing lithium and sodium hybrid capacitors. The current study provides new opportunities for developing greener and sustainable devices beyond conventional systems for next-generation storage applications.</P>

Graphene–Nanotube–Iron Hierarchical Nanostructure as Lithium Ion Battery Anode

Lee, Si-Hwa,Sridhar, Vadahanambi,Jung, Jung-Hwan,Karthikeyan, Kaliyappan,Lee, Yun-Sung,Mukherjee, Rahul,Koratkar, Nikhil,Oh, Il-Kwon American Chemical Society 2013 ACS NANO Vol.7 No.5

<P>In this study, we report a novel route <I>via</I> microwave irradiation to synthesize a bio-inspired hierarchical graphene–nanotube–iron three-dimensional nanostructure as an anode material in lithium-ion batteries. The nanostructure comprises vertically aligned carbon nanotubes grown directly on graphene sheets along with shorter branches of carbon nanotubes stemming out from both the graphene sheets and the vertically aligned carbon nanotubes. This bio-inspired hierarchical structure provides a three-dimensional conductive network for efficient charge-transfer and prevents the agglomeration and restacking of the graphene sheets enabling Li-ions to have greater access to the electrode material. In addition, functional iron-oxide nanoparticles decorated within the three-dimensional hierarchical structure provides outstanding lithium storage characteristics, resulting in very high specific capacities. The anode material delivers a reversible capacity of ∼1024 mA·h·g<SUP>–1</SUP> even after prolonged cycling along with a Coulombic efficiency in excess of 99%, which reflects the ability of the hierarchical network to prevent agglomeration of the iron-oxide nanoparticles.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2013/ancac3.2013.7.issue-5/nn4007253/production/images/medium/nn-2013-007253_0007.gif'></P>