Improved cyclability of Nickel-rich layered oxides

ABSTRACTThis study compares the physico- and electro- chemical properties of LiNi0.8Mn0.10Co0.1O2 (NMC811) and LiNi0.83Mn0.06Co0.09Al0.1O2 (NMCA) prepared by an oxalic acid co-precipitation. Deposition of a SiO2 surface coating was attempted via reaction of the powder with an amino silane prior to the final heat treatment. It was found that either the presence of small amounts of Al3+, or the compositional gradient resulting from a two step co-precipitation, caused increased crystal growth of the NMCA in comparison to NMC811. This led to improved cyclability in LP40 electrolyte. However, the SiO2 coating appeared incomplete and negatively impacted performance. Crystal cleavage preferably on the {001} planes was observed after 100 charge-discharge cycles, with consequent cathode electrolyte interphase formation in the crystal cracks. This is believed to cause capacity decay via lithium loss, and increased charge transfer resistance. An FEC based electrolyte improved the cyclability in all cases and even under extreme conditions (45°C and upper cycling potential of 4.5 V) NMCA showed a capacity retention of 85% after 100 cycles.

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Electrochemical Properties of Nanocrystalline Y2-xPrxRu2O7 Pyrochlore for Electrodic Application in IT-SOFCS

MRS Proceedings ◽

10.1557/proc-0972-aa03-08 ◽

2006 ◽

Vol 972 ◽

Author(s):

Chiara Abate ◽

Keith Duncan ◽

Enrico Traversa ◽

Eric Wachsman

Keyword(s):

Cathode Material ◽

Phase Boundary ◽

Electrochemical Impedance ◽

Charge Transfer Resistance ◽

Nanocrystalline Powders ◽

Precipitation Method ◽

Electrode Polarization ◽

Transfer Resistance ◽

Triple Phase Boundary ◽

Co Precipitation

AbstractNanocrystalline powders of Y2-xPrxRu2O7 were prepared by a co-precipitation method, and were tested as electrode on ESB and GDC electrolytes by electrochemical impedance spectroscopy in the 300-750°C temperatures range. The electrode polarization was studied as a function of the amount of praseodymium in the cathode material. Both systems, Y2-xPrxRu2O7/ESB and Y2-xPrxRu2O7/GDC, showed a similar variation of the electrode area specific resistance (ASR). Y1.5Pr0.5Ru2O7 cathode material presented the best performance, with ASR value of 0.19 Ωcm2 on ESB and 4.23 Ωcm2 on GDC at 700°C. Furthermore, the change in ASR with the oxygen partial pressure suggested that the rate limiting step is the surface diffusion of the adsorbed oxygen at the electrode surface to the triple-phase boundary. Thus, the low value of resistivity of the Y1.5Pr0.5Ru2O7 in contact with ESB results from a much lower charge transfer resistance compared to the Y2-xPrxRu2O7/GDC system, and a partial solid diffusion at the interface electrode/electrolyte that increases the effective triple phase boundary length. This suggests that Y2-xPrxRu2O7 is a promising material for cathode application in ESB-based electrolyte for intermediate temperature solid oxide fuel cells (IT-SOFCs).

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Electrochemical Performances of Yttrium Doped Li3V2–XYX(PO4)3/C Cathode Material for Lithium Secondary Battery

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11197 ◽

2015 ◽

Vol 15 (10) ◽

pp. 8042-8047 ◽

Cited By ~ 5

Author(s):

Minchan Jeong ◽

Hyun-Soo Kim ◽

Dong-Sik Bae ◽

Chang-Woo Lee ◽

Bong-Soo Jin

Keyword(s):

Electrochemical Impedance ◽

Rate Capability ◽

Cycling Performance ◽

Charge Transfer Resistance ◽

Electrochemical Performances ◽

X Ray Diffraction ◽

Lithium Secondary Battery ◽

Capacity Retention ◽

Solid State Method ◽

Transfer Resistance

In this study, the Li3V2–X YX(PO4)3 compounds have been synthesized by a simple solid state method. In addition, a polyurethane was added to apply carbon coating on the surface of the Li3V2–X YX(PO4)3 particles for enhancement of the electrical conductivity. The crystal structure and morphology of the synthesized Li3V2–XYX(PO4)3/C (LVYP/C) was investigated using an X-ray diffraction (XRD) and a scanning electron microscopy (SEM) systematically. The electrochemical performance of synthesized material, such as the initial capacity, rate capability, cycling performance and EIS was evaluated. The sizes of synthesized particle ranged from 1 to 5 μm. The Li3V2–XYX(PO4)3/C (X = 0.02) delivered the initial discharge capacity of 171.5 mAh · g–1 at 0.1C rate. It showed a capacity retention ratio of 73.0% at 1.0C after 100th cycle. The electrochemical impedance spectroscopies (EIS) results revealed that the charge transfer resistance of the material decreases by Y doping.

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Influence of Carbon Inclusion on the Electrochemical Performances for Si Using as the Lithium-Ion Battery Anode

Materials Science Forum ◽

10.4028/www.scientific.net/msf.852.811 ◽

2016 ◽

Vol 852 ◽

pp. 811-815

Author(s):

Yue Qin Ban ◽

Wei Quan Shao ◽

Sha Ou Chen ◽

Li Zhu He ◽

Hai Ling Zhu ◽

...

Keyword(s):

Discharge Capacity ◽

Lithium Ion ◽

Charge Transfer Resistance ◽

Electrochemical Performances ◽

Capacity Retention ◽

Transfer Resistance ◽

Conductive Pathway ◽

Initial Discharge ◽

Lower Charge ◽

Carbon Inclusion

Si/C composite was prepared using different procedures and different C sources in this work. According to the electrochemical performances, it was found that the discharge capacity for Si/C composite (SC1) by the electrostatic spinning procedure using polyvinylpyrrolidone as the C source was 2200mAh/g. In contrast, the cell with the pure Si particle exhibited an initial discharge capacity of only 13mAh/g. Moreover, after 30 cycles, SC1 sample had the higher capacities and the better capacity retention performances than other samples because of its lower charge transfer resistance. The inclusion of carbon not only worked as a stable electric conductive pathway but also buffer the volume expansion of the silicon during the process of charging and discharging.

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Surface Coating and Electrochemical Properties of LiNi0.8Co0.15Al0.05O2 Cathode in Lithium-Ion Cells

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1058.317 ◽

2014 ◽

Vol 1058 ◽

pp. 317-320 ◽

Cited By ~ 4

Author(s):

Lin Zhang ◽

Fei Luo ◽

Jian Hua Wang ◽

Yu Zhong Guo

Keyword(s):

Surface Coating ◽

Coating Layer ◽

Lithium Ion ◽

Precipitation Method ◽

Initial Discharge Capacity ◽

Capacity Retention ◽

Lithium Ion Cells ◽

Initial Discharge ◽

Co Precipitation ◽

Initial Capacity

LiNi0.8Co0.15Al0.05O2, as the cathode materials for lithium ion battery, were prepared from the precursors, Ni0.8Co0.15Al0.05(OH)2 which were synthesized by chemical co-precipitation method. LiNi0.8Co0.15Al0.05O2 particles are modified with AlF3 and AlPO4. Even though the initial discharge capacity of the coated LiNi0.8Co0.15Al0.05O2 was decreased that of the pristine material, the capacity retention and the thermal stability, in a highly oxidized state are both significantly improved. This effect is attributed to the thin coating layer protecting the oxidized cathode particles from being attacked by hydrogen fluoride in the electrolyte. The cycling behavior of the AlF3-coated LiNi0.8Co0.15Al0.05O2 is quite stable showing good capacity retention (96.3% of its initial capacity after 30 cycles).

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Effect of Structural and Electrochemical Properties of Yttrium-doped LiNi0.90Co0.05Al0.05O2 Electrode by Co-precipitation for Lithium Ion-batteries

Journal of New Materials for Electrochemical Systems ◽

10.14447/jnmes.v18i1.382 ◽

2015 ◽

Vol 18 (1) ◽

pp. 009-016 ◽

Cited By ~ 3

Author(s):

Gi-Won Yoo ◽

Tae-Jun Tae-Jun Park ◽

Jong-Tae Son

Keyword(s):

Electrochemical Properties ◽

Rate Capability ◽

Lithium Ion ◽

Solid State Reaction Method ◽

Charge Transfer Resistance ◽

Hexagonal Structure ◽

High Rate ◽

Transfer Resistance ◽

Cation Mixing ◽

Co Precipitation

In this study, the LiNi0.90−xCo0.05Al0.05YxO2 (x = 0, 0.025, 0.075) have been synthesized by a co-precipitation and solid-state reaction method. The effect of the Y3+-doping on the structural and electrochemical properties were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and by electrochemical and impedance spectroscopy (EIS). From the results of the XRD pattern changes between before and after the doping, less cation mixing and more ordered hexagonal structure were observed for the LiNi0.875Co0.05Al0.05Y0.025O2 cathode and the cell delivered an initial discharge capacity of 195.8 mAhg-1 and was 10.2 mAhg-1 higher than the pristine cell by yttrium doping effect. High rate capability studies were also performed and showed the capacity retention of 95, 81.7 and 63.8 % at 0.2, 1.0 and 5.0 C-rate, respectively during the cycling. The impedance spectra showed that the charge transfer resistance for the pristine cathode grew significantly, while that for the Y3+-doped cathode decreased during cycling. It was concluded that the capacity fading for LiNi0.90Co0.05Al0.05O2 mainly due to the cation mixing, partially contributed by the impedance growth and by doping the pristine material with Y3+, cation mixing can be efficiently suppressed, which results in the improved rate capability.

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Improved Electrochemical and Mechanical Properties of Poly(vinylpyrrolidone)/Nafion® Membrane for Fuel Cell Applications

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2020.18979 ◽

2020 ◽

Vol 20 (12) ◽

pp. 7793-7799

Author(s):

M. D. Lutful Kabir ◽

Subir Paul ◽

Sang-June Choi ◽

Hee Jin Kim

Keyword(s):

Fuel Cells ◽

Proton Exchange Membrane ◽

Electrochemical Impedance ◽

Chemical Properties ◽

Charge Transfer Resistance ◽

Vital Role ◽

Exchange Capacity ◽

Proton Exchange ◽

Membrane Electrode ◽

Transfer Resistance

A novel blend of membranes made of Nafion® and poly(vinylpyrrolidone) (PVP) was prepared and characterized to investigate its applicability in proton exchange membrane fuel cells (PEMFCs). In addition to being effectively proton conductive, the membranes exhibited better mechanical strength, chemical stability, and adequate water retention ability, as well as ion exchange capacity comparable to that of cast Nafion® membrane. The data obtained from an electrochemical impedance spectroscopy (EIS) fitting of the fuel cells revealed the membrane electrode assemblies (MEAs) made of 0.5 wt.% PVP/Nafion® had lower ohmic and charge transfer resistance compared with that of the Nafion® membrane. The intermolecular interactions and morphology of these membranes were assessed using Fourier-transform infrared spectroscopy and field-emission scanning electron microscopy. The results of the performance curve indicate that the introduction of PVP as a modifier played a vital role in improving membrane performance. Accordingly, this solution-casted polymer electrolyte membrane with suitable PVP content offers a simple way to improve electrochemical, mechanical, and chemical properties, and thereby promises the prospect of use in low-temperature PEMFCs.

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Catalyst-Doped Anodic TiO2 Nanotubes: Binder-Free Electrodes for (Photo)Electrochemical Reactions

Catalysts ◽

10.3390/catal8110555 ◽

2018 ◽

Vol 8 (11) ◽

pp. 555 ◽

Cited By ~ 12

Author(s):

Hyeonseok Yoo ◽

Moonsu Kim ◽

Yong-Tae Kim ◽

Kiyoung Lee ◽

Jinsub Choi

Keyword(s):

Charge Transfer ◽

Tio2 Nanotubes ◽

Chemical Properties ◽

Water Electrolysis ◽

Charge Transfer Resistance ◽

Electrochemical Anodization ◽

Electrochemical Reactions ◽

Charge Transfer Reaction ◽

Transfer Resistance ◽

Physical And Chemical

Nanotubes of the transition metal oxide, TiO2, prepared by electrochemical anodization have been investigated and utilized in many fields because of their specific physical and chemical properties. However, the usage of bare anodic TiO2 nanotubes in (photo)electrochemical reactions is limited by their higher charge transfer resistance and higher bandgaps than those of semiconductor or metal catalysts. In this review, we describe several techniques for doping TiO2 nanotubes with suitable catalysts or active materials to overcome the insulating properties of TiO2 and enhance its charge transfer reaction, and we suggest anodization parameters for the formation of TiO2 nanotubes. We then focus on the (photo)electrochemistry and photocatalysis-related applications of catalyst-doped anodic TiO2 nanotubes grown on Ti foil, including water electrolysis, photocatalysis, and solar cells. We also discuss key examples of the effects of doping and the resulting improvements in the efficiency of doped TiO2 electrodes for the desired (photo)electrochemical reactions.

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Electrochemical Properties and Ex Situ Study of Sodium Intercalation Cathode P2/P3-NaNi1/3Mn1/3Co1/3O2

Journal of Chemistry ◽

10.1155/2021/9492571 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Minh Le Nguyen ◽

Hoang Van Nguyen ◽

Man Van Tran ◽

Phung My Loan Le

Keyword(s):

Electrochemical Properties ◽

Electrochemical Impedance ◽

Sol Gel ◽

Charge Transfer Resistance ◽

Ex Situ ◽

Layered Oxides ◽

Transfer Resistance ◽

Complex Phase ◽

Voltage Range ◽

Sol Gel Process

In recent work, P2/P3-NaNi1/3Mn1/3Co1/3O2 (NaNMC) was obtained by the sol-gel process followed by calcination of the precursor at 900°C for 12 h. The electrochemical properties of NaNMC were investigated in the voltage range of 2.0–4.0 V. The material exhibited an initial discharge capacity of 107 mAh·g−1 and good capacity retention of 82.2% after 100 cycles. Ex situ XRD performance showed that the P3-phase transformed from the P3- to O1-phase and vice versa, while the P2-phase remained stable during the sodium intercalation. The kinetic of sodium intercalation of NaNMC upon reversible Na+ insertion/deinsertion was evaluated via a Galvanostatic Intermittence Titration Technique (GITT) and Electrochemical impedance spectroscopy (EIS). The diffusion coefficients of Na+ ion deduced from the GITT curve have a broad distribution ranging from 10−10 to 10−11 cm2·s−1 for the charging/discharging process. Besides, the evolution of diffusion coefficient and charge transfer resistance is consistent with the complex phase transition generally observed in sodium layered oxides.

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Improvement of Ti/RuO2–IrO2 Anode Lifetime and Electrocatalytical Properties by Using an Eco-Friendly Thermal Decomposition Method Using Polyvinyl Alcohol as Solvent

10.26434/chemrxiv.7991129 ◽

2019 ◽

Author(s):

Charlys Bezerra ◽

Géssica Santos ◽

Marilia Pupo ◽

Maria Gomes ◽

Ronaldo Silva ◽

...

Keyword(s):

Thermal Decomposition ◽

Polyvinyl Alcohol ◽

High Efficiency ◽

Electrochemical Impedance ◽

Pechini Method ◽

Low Cost ◽

Charge Transfer Resistance ◽

Transfer Resistance ◽

Calcination Temperatures ◽

Service Lifetime

Electrochemical oxidation processes are promising solutions for wastewater treatment due to their high efficiency, easy control and versatility. Mixed metal oxides (MMO) anodes are particularly attractive due to their low cost and specific catalytic properties. Here, we propose an innovative thermal decomposition methodology using <a>polyvinyl alcohol (PVA)</a> as a solvent to prepare Ti/RuO2–IrO2 anodes. Comparative anodes were prepared by conventional method employing a polymeric precursor solvent (Pechini method). The calcination temperatures studied were 300, 400 and 500 °C. The physical characterisation of all materials was performed by X-ray diffraction and scanning electron microscopy coupled with energy dispersive spectroscopy, while electrochemical characterisation was done by cyclic voltammetry, accelerated service lifetime and electrochemical impedance spectroscopy. Both RuO2 and IrO2 have rutile-type structures for all anodes. Rougher and more compact surfaces are formed for the anodes prepared using PVA. Amongst temperatures studied, 300 °C using PVA as solvent is the most suitable one to produce anodes with expressive increase in voltammetric charge (250%) and accelerated service lifetime (4.3 times longer) besides reducing charge-transfer resistance (8 times lower). Moreover, the electrocatalytic activity of the anodes synthesised with PVA toward the Reactive Blue 21 dye removal in chloride medium (100 % in 30 min) is higher than that prepared by Pechini method (60 min). Additionally, the removal total organic carbon point out improved mineralisation potential of PVA anodes. Finally, this study reports a novel methodology using PVA as solvent to synthesise Ti/RuO2–IrO2 anodes with improved properties that can be further extended to synthesise other MMO compositions.

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