Browsing by Author "Patra, Jagabandhu"

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A Holey Graphene Additive for Boosting Performance of Electric Double-Layer Supercapacitors
(2020-04-01)
Huang, Jun-Bin
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Patra, Jagabandhu
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Lin, Ming-Hsien
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Ger, Ming-Der
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Liu, Yih-Ming
We demonstrate a facile and effective method, which is low-cost and easy to scale up, to fabricate holey graphene nanosheets (HGNSs) via ultrafast heating during synthesis. Various heating temperatures are used to modify the material properties of HGNSs. First, we use HGNSs as the electrode active materials for electric double-layer capacitors (EDLCs). A synthesis temperature of 900 degrees C seems to be optimal, i.e., the conductivity and adhesion of HGNSs reach a compromise. The gravimetric capacitance of this HGNS sample (namely HGNS-900) is 56 Fg(-1). However, the volumetric capacitance is low, which hinders its practical application. Secondly, we incorporate activated carbon (AC) into HGNS-900 to make a composite EDLC material. The effect of the AC:HGNS-900 ratio on the capacitance, high-rate performance, and cycling stability are systematically investigated. With a proper amount of HGNS-900, both the electrode gravimetric and volumetric capacitances at high rate charging/discharging are clearly higher than those of plain AC electrodes. The AC/HGNS-900 composite is a promising electrode material for nonaqueous EDLC applications.
A Novel Moisture-Insensitive and Low-Corrosivity Ionic Liquid Electrolyte for Rechargeable Aluminum Batteries
(1970-01-01)
Li, Chi
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Patra, Jagabandhu
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Li, Ju
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Rath, Purna Chandra
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Lin, Ming-Hsien
Rechargeable aluminum batteries (RABs) are extensively developed due to their cost-effectiveness, eco-friendliness, and low flammability and the earth abundance of their electrode materials. However, the commonly used RAB ionic liquid (IL) electrolyte is highly moisture-sensitive and corrosive. To address these problems, a 4-ethylpyridine/AlCl3 IL is proposed. The effects of the AlCl3 to 4-ethylpyridine molar ratio on the electrode charge-discharge properties are systematically examined. A maximum graphite capacity of 95 mAh g(-1) is obtained at 25 mA g(-1). After 1000 charge-discharge cycles, approximate to 85% of the initial capacity can be retained. In situ synchrotron X-ray diffraction is employed to examine the electrode reaction mechanism. In addition, low corrosion rates of Al, Cu, Ni, and carbon-fiber paper electrodes are confirmed in the 4-ethylpyridine/AlCl3 IL. When opened to the ambient atmosphere, the measured capacity of the graphite cathode is only slightly lower than that found in a N-2-filled glove box; moreover, the capacity retention upon 100 cycles is as high as 75%. The results clearly indicate the great potential of this electrolyte for practical RAB applications.
A Water-Soluble NaCMC/NaPAA Binder for Exceptional Improvement of Sodium-Ion Batteries with an SnO2-Ordered Mesoporous Carbon Anode
(2018-11-23)
Patra, Jagabandhu
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Rath, Purna Chandra
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Li, Chi
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Kao, Hsien-Ming
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Wang, Fu-Ming
SnO2@CMK-8 composite, a highly promising anode for Na-ion batteries (NIBs), was incorporated with polyvinylidene difluoride (PVDF), sodium carboxymethylcellulose (NaCMC), sodium polyacrylate (NaPAA), and NaCMC/NaPAA mixed binders to optimize the electrode sodiation/desodiation properties. Synergistic effects between NaCMC and NaPAA led to the formation of an effective protective film on the electrode. This coating layer not only increased the charge-discharge Coulombic efficiency, suppressing the accumulation of solid-electrolyte interphases, but also kept the SnO2 nanoparticles in the CMK-8 matrix, preventing the agglomeration and removal of oxide upon cycling. The adhesion strength and stability towards the electrolyte of the binders were evaluated. In addition, the charge-transfer resistance and apparent Na+ diffusion of the SnO2@CMK-8 electrodes with various binders were examined and post-mortem analyses were conducted. With NaCMC/NaPAA binder, exceptional electrode capacities of 850 and 425 mAh g(-1) were obtained at charge-discharge rates of 20 and 2000 mA g(-1), respectively. After 300 cycles, 90 % capacity retention was achieved. The thermal reactivity of the sodiated electrodes was studied by using differential scanning calorimetry. The binder effects on NIB safety, in terms of thermal runaway, are discussed.
Carbonaceous Anodes Derived from Sugarcane Bagasse for Sodium-Ion Batteries
(2019-05-21)
Rath, Purna Chandra
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Patra, Jagabandhu
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Huang, Hao-Tzu
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Bresser, Dominic
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Wu, Tzi-Yi
To realize the sustainability of Na-ion batteries (NIBs) for large-scale energy storage applications, a resource-abundant and cost-effective anode material is required. In this study, sugarcane bagasse (SB), one of the most abundant types of biowaste, is chosen as the carbon precursor to produce a hard carbon (HC) anode for NIBs. SB has a great balance of cellulose, hemicellulose, and lignin, which prevents full graphitization of the pyrolyzed carbon but ensures a sufficiently ordered carbon structure for Na+ transport. Compared with HC derived from waste apples, which are pectin-rich and have less cellulose than SB, SB-derived HC (SB-HC) has fewer defects and a lower oxygen content. SB-HC thus has a higher first-cycle sodiation/desodiation coulombic efficiency and better cycling stability. In addition, SB-HC has a unique flake-like morphology, which can shorten the Na+ diffusion length, and higher electronic conductivity (owing to more sp(2)-hybridized carbon), resulting in superior high-rate charge-discharge performance to apple-derived HC. The effects of pyrolysis temperature on the material characteristics and electrochemical properties, evaluated by using chronopotentiometry, cyclic voltammetry, and electrochemical impedance spectroscopy, are systematically investigated for both kinds of HC.
Composition Modulation of Ionic Liquid Hybrid Electrolyte for 5 V Lithium-Ion Batteries
(2019-11-13)
Wu, Chia-Jung
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Rath, Puma Chandra
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Patra, Jagabandhu
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Bresser, Dominic
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Passerini, Stefano
Electrolyte is a key component in high-voltage lithium-ion batteries (LIBs). Bis(trifluoromethanesulfonyl)imide-based ionic liquid (IL)/organic carbonate hybrid electrolytes have been a research focus owing to their excellent balance of safety and ionic conductivity. Nevertheless, corrosion of Al current collectors at high potentials usually happens for this kind of electrolyte. In this study, this long-standing problem is solved via the modulation of the IL/carbonate ratio and LiPF6 concentration in the hybrid electrolyte. The proposed electrolyte suppresses Al dissolution and electrolyte oxidation at 5 V (vs Li+/Li) and thus allows for ideal lithiation/delithiation performance of a high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode even at 55 degrees C. The underlying mechanism is examined in this work. Excellent cycling stability (97% capacity retention) for an LNMO cathode after 300 cycles is achieved. This electrolyte shows good wettability toward a polyethylene separator and low flammability. In addition, satisfactory compatibility with both graphite and Si-based anodes is confirmed. The proposed electrolyte design strategies have great potential for applications in high-voltage LIBs.
Ga-doped lithium lanthanum zirconium oxide electrolyte for solid-state Li batteries
(2020-09-01)
Mishra, Mrinalini
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Hsu, Che-Wei
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Rath, Purna Chandra
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Patra, Jagabandhu
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Lai, Hong-Zheng
Cubic-phase Li7La3Zr2O12 (LLZO) garnet is a promising solid electrolyte candidate for next-generation Li batteries. As a viable approach, the desired cubic-phase formation of LLZO relies on elemental doping. In this regard, various dopants such as Al and Ga are doped into the LLZO samples, which are synthesized using a solid-state reaction method. The Al-and Ga-doped LLZO can transform to a cubic-phase garnet at 900 degrees C. After 1200 degrees C sintering, a Li2ZrO3 impurity phase is found for the Al-doped LLZO pellet, which still shows many voids and inhomogeneous particles on the surface. The Ga doping seems to be attractive since it can effectively stabilize the cubic phase and desired microstructure within 900-1200 degrees C. Based on the optimized Ga-doped LLZO (LGLZO), various electrolyte architecture designs are developed that include LGLZO pellet electrolytes with and without poly(ethylene oxide) (PEO)-lithium bis(tri-fluoromethylsulfonyl)imide (LiTFSI)-LGLZO coating, and hybrid electrolyte layers of PEO-LiTFSI, PEO-LGLZO, and PEO-LiTFSI-LGLZO composites. Li//LiFePO4 (LFP) cells with various types of electrolytes are assembled, and their charge-discharge properties are investigated. The all-solid-state Li//PEO-LiTFSI-LGLZO//LFP cell exhibits satisfactory charge storage performance, which has revealed potential for practical applications. (c) 2020 Elsevier Ltd. All rights reserved.
Highly concentrated carbonate electrolyte for Li-ion batteries with lithium metal and graphite anodes
(2020-02-29)
Xie, Jian-De
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Patra, Jagabandhu
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Rath, Purna Chandra
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Liu, Weng-Jing
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Su, Ching-Yuan
Highly concentrated lithium bis(fluorosulfonyflimide (LiFSI) salt dissolved in carbonate solvent is employed as a high-performance and robust organic electrolyte for Li-ion batteries. The influences of Li salt type, concentration, and solvent type (such as diethyl carbonate (DEC), dimethyl carbonate (DMC), and ethylene carbonate (EC)) on the electrochemical properties of Li metal and graphite anodes are systematically assessed. A superior electrolyte composition of 5.5 M LiFSI-DMC/EC is achieved, enhancing the anti-flammability, coulombic efficiency, and high rate capability. The optimal efficiency values of Li electrodeposition/stripping utilizing 5.5 M LiFSI-DMC/EC are 97.0% and 94.5% at 0.4 and 6 mA cm(-2), respectively. Such an enhanced performance is due to the formation of a three-dimensional ion network, composed of contact ion pairs (CIPs) and ion aggregates (AGGs) in the highly concentrated LiFSI electrolyte, which effectively decreases the number of free solvent molecules and inhibits the formation of undesired dendritic Li structures. Raman spectroscopy is employed to confirm the formation of CIP and AGG compounds within the electrolyte. The electrochemical data of the 5.5 M LiFSI-DMC/EC electrolyte cell demonstrates a remarkable improvement in the specific capacity and rate capability of a graphite anode.
Hybrid electrolyte enables safe and practical 5 V LiNi0.5Mn1.5O4 batteries
(2019-07-21)
Rath, Purna Chandra
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Wu, Chia-Jung
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Patra, Jagabandhu
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Li, Ju
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Lee, Tai-Chou
Bis(trifluoromethylsulfonyl)imide (TFSI)-based ionic liquid (IL) has high thermal and electrochemical stability, but it is not an ideal battery electrolyte due to the poor rate capability of cells that use it, problematic anode compatibility, and high cost. The incorporation of a carbonate solvent could mitigate these problems, but it would also lead to serious Al current collector corrosion at high potential. This long-existing problem is overcome in this study by modulating the LiTFSI concentration and IL/carbonate ratio in the hybrid electrolyte. The Al corrosion and electrolyte decomposition side reactions at 5 V (vs. Li+/Li) can be suppressed in 3 M LiTFSI 25%-IL electrolyte, in which good performance of a high-voltage LiNi0.5Mn1.5O4 (LNMO) cathode is achieved. Capacities of 140 and 88 mA h g(-1) were measured at 0.1 and 2C, respectively (vs. 25 mA h g(-1) at 2C for a plain LiTFSI/PMP-TFSI IL electrolyte). After 300 charge-discharge cycles, 90% of the initial LNMO capacity was retained. This electrolyte also shows low flammability and great wettability toward a polyethylene separator. Moreover, this electrolyte allows elevated-temperature storage and operation of LNMO cells at 55 degrees C, which is not possible with the conventional carbonate electrolyte. Good compatibility of the electrolyte with a graphite anode is also demonstrated. The proposed electrolyte design concept has great potential for next-generation 5 V Li-ion batteries.
Hydrous ruthenium oxide-tantalum pentoxide thin film electrodes prepared by thermal decomposition for electrochemical capacitors
(2020-07-01)
Xie, Jian-De
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Hsu, Kai-Hsiang
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Patra, Jagabandhu
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Su, Ching-Yuan
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Lee, Sheng-Wei
In this work, we have fabricated high-performance thin-film electrodes for electrochemical capacitors (ECs) via thermal decomposition syntheses of RuO2-Ta2O5 coating layers on Ti substrates. The influences of decomposition temperature as well as the Ru/Ta molar ratio on material and electrochemical properties of the EC electrodes are systematically investigated. The thermal decomposition of 300 degrees C preserves a large fraction of hydrous RuO2 center dot xH(2)O within the hybrid oxide and consequently improves the electrode capacitance. The amorphous Ta2O5 incorporation can manipulate the RuO2 crystallinity and thus its specific capacitance. An optimal Ru/Ta molar ratio of 7:3 is determined for the RuO2-Ta2O5 electrode, which can deliver an energy density of 4.8 Wh kg(-1) at a power density of 8720 W kg(-1) (or 8.3 Wh L-1 at 15,000 W L-1). In addition, an excellent durability of 97.6% capacitance retention after 3000 charge-discharge cycles is found for this electrode. The proposed RuO2-Ta2O5 thin-film electrode has paved the way for next-generation ECs with superior capacitances, energy/power densities, and cyclability.
Ionic Liquids with Various Constituent Ions To Optimize Non-Enzymatic Electrochemical Detection Properties of Graphene Electrodes
(2019-10-07)
Xie, Jian-De
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Wang, Chueh-Han
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Patra, Jagabandhu
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Rath, Purna Chandra
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Gandomi, Yasser Ashraf
Palladium (Pd) nanoparticles, ionic liquids (ILs), or both are integrated with graphene sheets to serve as an electrochemical sensor for detecting various bio-species. Ascorbic acid (AA), uric acid (UA), and dopamine (DA) are used as the model analytes. To assess the effects of the constituent ions of ILs on sensing properties, various ILs, namely, EMI-SCN, EMI-DCA, BMP-DCA, BMI-PF6, EMI-NTF2, and BMP-NTF2, are investigated. The results demonstrate that the graphene/IL electrode shows superior detection sensitivity compared to those of the graphene/Pd and graphene/Pd/IL electrodes. Interestingly, the IL anions are found to play a crucial role in sensing performance. Angle-resolved X-ray photoelectron spectroscopy reveals that graphene can create an aligned cation/anion orientation in the adsorbed IL film, with the anions preferentially occupying the topmost surface, thus dominating the interaction with analytes. The graphene/EMI-SCN electrode shows the highest sensitivity among the electrodes, 1.49 mu A mu M-1 cm(-2), and a detection limit of 0.11 mu M toward DA. Even with large excesses of AA and UA, the concentration of DA can be effectively detected.
Manipulation of Nitrogen-Heteroatom Configuration for Enhanced Charge-Storage Performance and Reliability of Nanoporous Carbon Electrodes
(2020-07-22)
Sutarsis
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Patra, Jagabandhu
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Su, Ching-Yuan
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Li, Ju
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Bresser, Dominic
In this study, various nitrogen-containing functional groups, namely, pyridine (N-6), pyrrole (N-5), oxidized N (N-O), and quaternary N (N-Q), are created on activated carbon (AC) surface via melamine, ammonia, and nitric oxide doping methods. N-5 and N-6 groups markedly alter the specific surface area and pore size of AC. N-O is found to affect electrolyte wettability, and the N-Q content is closely associated with AC electronic conductivity. The nitrogen-containing groups do not contribute to pseudocapacitance in propylene carbonate and acetonitrile electrolytes. However, the nitric-oxide-treated carbon (AC-NO) exhibits the best highrate charge-discharge performance among the investigated materials. The N-Q-enriched and N-5/N-6-depleted AC-NO most effectively suppresses the leakage current and gas evolution of supercapacitors. Online gas chromatography is used to analyze the gaseous species produced from AC electrodes. With an appropriate surface functionality on carbon, the cell voltage can be increased to similar to 3 V, increasing the energy and power densities. The aging behavior of the carbon electrodes with and without nitrogen modification after being floated at 2.5 V and 70 degrees C for 3 days is investigated. An effective strategy for enhancing supercapacitor performance and reliability is proposed.
Supercapacitive Properties of Micropore- and Mesopore-Rich Activated Carbon in Ionic-Liquid Electrolytes with Various Constituent Ions
(2019-01-24)
Quoc Dat Nguyen
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Patra, Jagabandhu
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Hsieh, Chien-Te
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Li, Jianlin
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Dong, Quan-Feng
Ionic-liquid (IL) electrolytes, characterized by large potential windows, intrinsic ionic conductivity, low environmental hazard, and high safety, are used for micropore- and mesopore-rich activated-carbon (AC(micro) and AC(meso)) supercapacitors. IL electrolytes consisting of various cations [1-ethyl-3-methylimidazolium (EMI+), N-propyl-N-methylpyrrolidinium (PMP+), and N-butyl-N-methylpyrrolidinium (BMP+)] and various anions [bis(trifluoromethylsulfonyl)imide (TFSI-), BF4-, and bis(fluorosulfonyl)imide (FSI-)] are investigated. The electrolyte conductivity, viscosity, and ion transport properties at the AC(micro) and AC(meso) electrodes are studied. In addition, the capacitance, rate capability, and cycling stability of the two types of AC electrodes are systematically examined and post-mortem material analyses are conducted. The effects of IL composition on the charge-discharge capacitances of the AC(micro) electrodes are more pronounced than those for the AC(meso) electrodes. The FSI-based IL electrolytes, for which electrochemical properties are cation dependent, are found to be promising. Incorporating EMI+ with FSI- results in a low electrolyte viscosity and a fast ion transport, giving rise to optimized electrode capacitance and rate capability. Replacing EMI+ with PMP+ increases the cell voltage (to 3.5 V) and maximum energy density (to 42 Wh kg(-1)) of the AC(micro) cell at the cost of cycling stability.
Superior coulombic efficiency of lithium anodes for rechargeable batteries utilizing high-concentration ether electrolytes
(2019-10-01)
Xie, Jian-De
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Liu, Weng-Jing
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Li, Chi
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Patra, Jagabandhu
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Gandomi, Yasser Ashraf
This study adopts high-concentration ether electrolytes to improve high-rate capability, cycling stability, and Coulombic efficiency (CE) for lithium ion batteries with lithium anode. A series of ether-based electrolytes including lithium bis(fluorosulfonyl) imide (LiFSI)-glyme/ethylene carbonate (EC), LiFSI-glyme/EC, LiFSI-diglyme/EC, LiFSI-triglyme/EC, LiFSI-tetraglyme (G4)/EC, and LiFSI-1,3-dioxolane (DOL)/EC, along with commonly used LiPF6-DEC/EC were prepared to delineate the influences of concentration, chain length, molecular structure (linear or ring ether), and EC additive on the electrochemical performance of Li anodes. An optimum composition for ether-based electrolyte was determined resulting in significant improvement in anti-flammability as well as CE at both low and high rates. At ultra-high current density operation (e.g. 6 mA cm(-2)), the CE was 95.5 and 97.1% with 3 M LiFSI-G4/EC and 3 M LiFSI-DOL/EC, respectively. Using 1 M LiPF6 carbonate-based electrolyte tend to grow a needle-like dendritic structure when depositing lithium metal on Cu foils, whereas high-concentration ether electrolyte promotes a knot-like and rounded Li metal microstructure. High concentration EC-based electrolytes, are capable of facilitating Li thorn almost in tandem with solvent molecules, thereby reducing the number of free molecules, reducing the chance of side reaction with Li metal, and subsequently inhibiting the formation of dendritic Li structures. (C) 2019 Elsevier Ltd. All rights reserved.