Neutron diffraction and electrochemical studies of LixNi1/3Mn1/3Co1/3O2

2004 ◽  
Vol 835 ◽  
Author(s):  
Shih-Chieh Yin ◽  
Young-Ho Rho ◽  
Ian Swainson ◽  
Linda F. Nazar
Keyword(s):  
Neutron Diffraction ◽  
Size Effects ◽  
High Capacity ◽  
Rate Capability ◽  
Site Occupancy ◽  
Chemical Oxidation ◽  
Synthesis Methods ◽  
Electrochemical Studies ◽  
Cation Disorder ◽  
Complete Extraction

ABSTRACTAmongst solid solutions of the Li-Ni-Mn-Co-O series, LiNi1/3Mn1/3Co1/3O2 has received much attention owing to its high capacity and thermal stability. A major issue in these ordered rock salt structures is the irreversibility on the first cycle, and degree of Li+/Ni2+ cation disorder which inhibits the rate capability. To examine these factors, different synthesis methods were employed which led to LiNi1/3Mn1/3Co1/3O2 that exhibited varying degrees of cation disorder. Neutron diffraction studies were carried out on samples (LixNi1/3Mn1/3Co1/3O2, x = 1.00 → 0.04) prepared by chemical oxidation. The studies reveal that the extent of Ni2+/Li+ disorder between the 3b and 3a sites was preserved on Li extraction and re-insertion. Complete extraction of lithium to form the O1 phase was achieved in some materials. However, reformation of the O3 phase on chemical relithiation does not occur in these cases, whereas materials that only partly convert to the Ol phase exhibit complete conversion back to the O3 phase on relithiation. The differences are attributed to lithium site occupancy/stoichiometry and crystallite size effects.

Effects of Wet Chemical Oxidation on Surface Functionalization and Morphology of Highly Oriented Pyrolytic Graphite

2020 ◽  
Author(s):  
Mikhail Trought ◽  
Isobel Wentworth ◽  
Timothy Leftwich ◽  
Kathryn Perrine
Keyword(s):  
Surface Functionalization ◽  
Functional Group ◽  
Pyrolytic Graphite ◽  
Surface Oxidation ◽  
Chemical Oxidation ◽  
Synthesis Methods ◽  
Acid Solutions ◽  
Highly Oriented Pyrolytic Graphite ◽  
Wet Chemical ◽  
Surface Morphologies

The knowledge of chemical functionalization for area selective deposition (ASD) is crucial for designing the next generation heterogeneous catalysis. Surface functionalization by oxidation was studied on the surface of highly oriented pyrolytic graphite (HOPG). The HOPG surface was exposed to with various concentrations of two different acids (HCl and HNO3). We show that exposure of the HOPG surface to the acid solutions produce primarily the same -OH functional group and also significant differences the surface topography. Mechanisms are suggested to explain these strikingly different surface morphologies after surface oxidation. This knowledge can be used to for ASD synthesis methods for future graphene-based technologies.

HIGH POWER PERFORMANCE OF MULTICOMPONENT OLIVINE CATHODE MATERIAL FOR LITHIUM-ION BATTERIES

2011 ◽  
Vol 04 (03) ◽  
pp. 299-303 ◽  
Author(s):  
ZHUO TAN ◽  
PING GAO ◽  
FUQUAN CHENG ◽  
HONGJUN LUO ◽  
JITAO CHEN ◽  
...  
Keyword(s):  
Transition Metal ◽  
Cathode Material ◽  
High Capacity ◽  
Rate Capability ◽  
Lithium Ion ◽  
Coprecipitation Method ◽  
Homogeneous Distribution ◽  
Power Performance ◽  
X Ray ◽  
Carbon Coated

A multicomponent olivine cathode material, LiMn0.4Fe0.6PO4 , was synthesized via a novel coprecipitation method of the mixed transition metal oxalate. X-ray diffraction patterns indicate that carbon-coated LiMn0.4Fe0.6PO4 has been prepared successfully and that LiMn0.4Fe0.6PO4/C is crystallized in an orthorhombic structure without noticeable impurity. Homogeneous distribution of Mn and Fe in LiMn0.4Fe0.6PO4/C can be observed from the scanning electron microscopy (SEM) and the corresponding energy dispersive X-ray spectrometry (EDS) analysis. Hence, the electrochemical activity of each transition metal in the olivine synthesized via coprecipitation method was enhanced remarkably, as indicated by the galvanostatic charge/discharge measurement. The synthesized LiMn0.4Fe0.6PO4/C exhibits a high capacity of 158.6 ± 3 mAhg-1 at 0.1 C, delivering an excellent rate capability of 122.6 ± 3 mAhg-1 at 10 C and 114.9 ± 3 mAhg-1 at 20 C.

Hierarchical coral-like MnCo2O4.5@Co-Ni LDH composites on Ni foam as promising electrodes for high-performance supercapacitor

2021 ◽  
Author(s):  
yajun JI ◽  
Fei Chen ◽  
Shufen Tan ◽  
Fuyong Ren
Keyword(s):  
Electrochemical Performance ◽  
Metal Oxides ◽  
High Performance ◽  
High Capacity ◽  
Rate Capability ◽  
Negative Electrode ◽  
High Energy ◽  
Hybrid Nanostructures ◽  
High Energy Density ◽  
Ni Foam

Abstract Transition metal oxides are generally designed as hybrid nanostructures with high performance for supercapacitors by enjoying the advantages of various electroactive materials. In this paper, a convenient and efficient route had been proposed to prepare hierarchical coral-like MnCo2O4.5@Co-Ni LDH composites on Ni foam, in which MnCo2O4.5 nanowires were enlaced with ultrathin Co-Ni layered double hydroxides nanosheets to achieve high capacity electrodes for supercapacitors. Due to the synergistic effect of shell Co-Ni LDH and core MnCo2O4.5, the outstanding electrochemical performance in three-electrode configuration was triggered (high area capacitance of 5.08 F/cm2 at 3 mA/cm2 and excellent rate capability of maintaining 61.69 % at 20 mA/cm2), which is superior to those of MnCo2O4.5, Co-Ni LDH and other metal oxides based composites reported. Meanwhile, the as-prepared hierarchical MnCo2O4.5@Co-Ni LDH electrode delivered improved electrical conductivity than that of pristine MnCo2O4.5. Furthermore, the as-constructed asymmetric supercapacitor using MnCo2O4.5@Co-Ni LDH as positive and activated carbon as negative electrode presented a rather high energy density of 220 μWh/cm2 at 2400 μW/cm2 and extraordinary cycling durability with the 100.0 % capacitance retention over 8000 cycles at 20 mA/cm2, demonstrating the best electrochemical performance compared to other asymmetric supercapacitors using metal oxides based composites as positive electrode material. It can be expected that the obtained MnCo2O4.5@Co-Ni LDH could be used as the high performance and cost-effective electrode in supercapacitors.

3D self-assembled VS4 microspheres with high pseudocapacitance as highly efficient anodes for Na-ion batteries

Nanoscale ◽  
2018 ◽  
Vol 10 (46) ◽  
pp. 21671-21680 ◽  
Author(s):  
Wenbin Li ◽  
Jianfeng Huang ◽  
Liangliang Feng ◽  
Liyun Cao ◽  
Shuwei He
Keyword(s):  
Active Sites ◽  
High Capacity ◽  
Rate Capability ◽  
High Rate ◽  
High Rate Capability ◽  
Highly Efficient ◽  
Pseudocapacitive Behavior ◽  
Surface Active ◽  
Self Assembled ◽  
Cycling Life

The decreasing crystallinity of VS4 microspheres greatly increases the surface active sites, and then promotes the pseudocapacitive behavior, and finally leads to the high capacity, long cycling life and high rate capability.

High Capacity and Rate Capability of Amorphous Phosphorus for Sodium Ion Batteries

2013 ◽  
Vol 52 (17) ◽  
pp. 4633-4636 ◽  
Author(s):  
Jiangfeng Qian ◽  
Xianyong Wu ◽  
Yuliang Cao ◽  
Xinping Ai ◽  
Hanxi Yang
Keyword(s):  
High Capacity ◽  
Rate Capability ◽  
Sodium Ion ◽  
Sodium Ion Batteries

Revealing a conversion-alloying reaction mechanism behind high capacity and rate capability of SnS/N-doped graphene anode by in situ TEM

2019 ◽  
Vol 297 ◽  
pp. 46-54 ◽  
Author(s):  
Libing Yao ◽  
Meng Nie ◽  
Chongyang Zhu ◽  
Ran Cai ◽  
Weiwei Xia ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
High Capacity ◽  
Rate Capability ◽  
In Situ Tem ◽  
Doped Graphene

scholarly journals CoMnO2-Decorated Polyimide-Based Carbon Fiber Electrodes for Wire-Type Asymmetric Supercapacitor Applications

2020 ◽  
Author(s):  
Young-Hun Cho ◽  
Jae-Gyoung Seong ◽  
Jae-Hyun Noh ◽  
Da-Young Kim ◽  
Yong-Sik Chung ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Carbon Fibers ◽  
Rate Capability ◽  
Ammonium Persulfate ◽  
Chemical Oxidation ◽  
Sem Analysis ◽  
Metal Nanostructures ◽  
Carbon Fiber Electrode ◽  
Coated Carbon ◽  
Fiber Electrode

In this work, we report the carbon fiber-based wire-type asymmetric supercapacitors (ASCs). The highly conductive carbon fibers were prepared by the carbonized and graphitized process using the polyimide (PI) as a carbon fiber precursor. To assemble the ASC device, the CoMnO2-coated and Fe2O3-coated carbon fibers were used as the cathode and the anode materials, respectively. FE-SEM analysis confirmed that the CoMnO2-coated carbon fiber electrode exhibited the porous hierarchical interconnected nanosheet structures, depending on the added amounts of ammonium persulfate (APS) as an oxidizing agent, and Fe2O3-coated carbon fiber electrode showed a uniform distribution of porous Fe2O3 nanorods over the surface of carbon fibers. The nanostructured CoMnO2 were directly deposited onto carbon fibers by a chemical oxidation route without high temperature treatments. In particular, the electrochemical properties of the CoMnO2-coated carbon fiber with the concentration of 6 mmol APS presented the enhanced electrochemical activity, probably due to its porous morphologies and good conductivity. Further, to reduce the interfacial contact resistance as well as improve the adhesion between transition metal nanostructures and carbon fibers, the carbon fibers were pre-coated with the Ni layer as a seed layer using an electrochemical deposition method. The fabricated ASC device delivered a specific capacitance of 221 F g-1 at 0.7 A g-1 and good rate capability of 34.8% at 4.9 A g-1. Moreover, the wire-type device displayed the superior energy density of 60.16 Wh kg-1 at a power density of 490 W kg-1 and excellent capacitance retention of 95% up to 3,000 charge/discharge cycles.

scholarly journals Borophene as a promising anode material for sodium-ion batteries with high capacity and high rate capability using DFT

RSC Advances ◽  
2018 ◽  
Vol 8 (32) ◽  
pp. 17773-17785 ◽  
Author(s):  
Jianhua Liu ◽  
Cheng Zhang ◽  
Lei Xu ◽  
Shaohua Ju
Keyword(s):  
Vapor Deposition ◽  
High Capacity ◽  
Rate Capability ◽  
Chemical Vapor ◽  
Sodium Ion ◽  
High Rate ◽  
Chemical Vapor Deposition Method ◽  
Sodium Ion Batteries ◽  
Light Weight ◽  
High Rate Capability

Two-dimensional boron synthesized by the chemical vapor deposition method is an atomically thin layer of boron with both light weight and metallicity.

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