scholarly journals New Insight into Li+ Dynamics in Lithium Bimetal Phosphate

2021 ◽  
Author(s):  
Laurence Savignac ◽  
John M. Griffin ◽  
Steen Brian Schougaard
Keyword(s):  
Electronic Conductivity ◽  
Nmr Relaxation ◽  
Structural Instability ◽  
Electrochemical Performances ◽  
Relaxation Techniques ◽  
Transition Mechanism ◽  
Expected Gain ◽  
Multiple Processes ◽  
Particle Level ◽  
Structural Contribution

Abstract Substitution of iron by other transition metals within the remarkably stable olivine framework is of interest considering the expected gain in energy density. However, manganese rich olivine materials suffer from sluggish redox kinetics, leading to electrochemical performances at high current densities which are below expectations. The source of the kinetic limitations is not clear, with multiple processes having been proposed, including low bulk electronic conductivity, structural instability of Mn3+ and a phase transition mechanism. This study employed 7Li MAS NMR relaxation techniques to indirectly probe Li+ dynamics using various stoichiometry of chemically prepared LixMnyFe1-yPO4 (0 ≤ (x, y) ≤ 1). Focusing on the particle level, the aim was to understand how the different crystal phases, alongside the Mn structural contribution, influence Li+ transport at each stage of the oxidation process. Significantly, the formation of an olivine solid solution with vacancies within this progression gave rise to a faster 7Li transverse relaxation derived from superior Li+ motion.

Synergistic effect of biomass-derived carbon and conducting polymer coatings on the supercapacitive energy storage performance of TiO2

2020 ◽  
Vol 62 (8) ◽  
pp. 814-819
Author(s):  
Ece Unur Yilmaz ◽  
M. Ebubekir Torbali
Keyword(s):  
Specific Capacitance ◽  
Mechanical Stability ◽  
Electronic Conductivity ◽  
Rate Capability ◽  
Cost Effective ◽  
Hydrothermal Carbonization ◽  
Polymer Coatings ◽  
Electrochemical Performances ◽  
Electrochemically Active ◽  
Supercapacitor Applications

Abstract The application of anatase titanium dioxide (TiO2), which is an abundant and cost effective resource, in supercapacitors has been restricted due to its poor electronic conductivity and limited mechanical stability. A biomass-derived carbon was coated on anatase TiO2 nanoparticles via practical and green hydrothermal carbonization in order to overcome these limitations. Hierarchically porous carbon provided a capacitive double layer for charge storage and the TiO2/C nanocomposite exhibited a specific capacitance of 61 F × g-1 (0.25 A × g-1, 0 to 1 V vs. Ag/AgCl, 1 M H2SO4 aqueous electrolyte). The TiO2/C/PEDOT:PSS nanocomposite with enhanced specific capacitance and rate capability (189 F × g-1 at 0.25 A × g-1, 161 F × g-1 at 0.5 A × g-1, 123 F × g-1 at 1 A × g-1, 91 F × g-1 at 2 A × g-1) was obtained by the application of an electrochemically active PEDOT:PSS layer. The prominent electrochemical and mechanical stability of the ternary nanocomposite was demonstrated by its ability to retain 98 % of its initial capacitance after 1500 cycles of charge-discharge at a high current rate (3 A × g-1). The synergistic use of sustainable organic and inorganic components with environmentally friendly and practical methods yields extremely promising electrochemical performances for supercapacitor applications. The TiO2/C/PEDOT:PSS nanocomposite presented in this work delivered an electrochemical performance comparable to its published counterparts which are obtained by more sophisticated or hazardous methods and with expensive components.

Electrochemical Performances of Li4Ti5-xAlxO12 (x=0.03, 0.05, 0.10) as Anode Materials for Lithium Ion Battery

2013 ◽  
Vol 750-752 ◽  
pp. 1791-1794
Author(s):  
Fang Gu
Keyword(s):  
Anode Materials ◽  
Solution Method ◽  
Electronic Conductivity ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Cycling Performance ◽  
Negative Influence ◽  
Electrochemical Process ◽  
Electrochemical Performances ◽  
X Ray Diffraction

Li4Ti5-xAlxO12(x=0.03, 0.05, 0.10) were prepared by a solution method. The electrochemical performances including charge-discharge and AC impedance were investigated. The structure of the samples were characterized by X-ray diffraction. The results revealed that proper Al doped into Li4Ti5O12would not change or destroy the crystal structure. Li4Ti5-xAlxO12(x=0.03, 0.05) had better capacity than Li4Ti5O12, because of the decrease of electric resistance. But when the quality percent of Al was too big, it will bring negative influence to Li4Ti5O12. Al3+doping did not change the electrochemical process, instead enhanced the electronic conductivity and ionic conductivity. The reversible capacity and cycling performance were effectively improved.

scholarly journals High-Performance Lithium Sulfur Batteries Based on Multidimensional Graphene-CNT-Nanosulfur Hybrid Cathodes

Batteries ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 26
Author(s):  
Álvaro Doñoro ◽  
Álvaro Muñoz-Mauricio ◽  
Vinodkumar Etacheri
Keyword(s):  
High Performance ◽  
Coulombic Efficiency ◽  
Electronic Conductivity ◽  
Specific Capacity ◽  
Synthesis Method ◽  
Graphene Nanoplatelets ◽  
Practical Implementation ◽  
Electrochemical Performances ◽  
High Electronic Conductivity ◽  
Lithium Sulfur

Although lithium-sulfur (Li-S) batteries are one of the promising candidates for next-generation energy storage, their practical implementation is limited by rapid capacity fading due to lithium polysulfide (LiPSs) formation and the low electronic conductivity of sulfur. Herein, we report a high-performance lithium-sulfur battery based on multidimensional cathode architecture consisting of nanosulfur, graphene nanoplatelets (2D) and multiwalled carbon nanotubes (1D). The ultrasonic synthesis method results in the generation of sulfur nanoparticles and their intercalation into the multilayered graphene nanoplatelets. The optimized multidimensional graphene-sulfur-CNT hybrid cathode (GNS58-CNT10) demonstrated a high specific capacity (1067 mAh g−1 @ 50 mA g−1), rate performance (539 @ 1 A g−1), coulombic efficiency (~95%) and cycling stability (726 mAh g−1 after 100 cycles @ 200 mA g−1) compared to the reference cathode. Superior electrochemical performances are credited to the encapsulation of nanosulfur between the individual layers of graphene nanoplatelets with high electronic conductivity, and effective polysulfide trapping by MWCNT bundles.

scholarly journals Carbon Nanotubes: Applications to Energy Storage Devices

2020 ◽  
Author(s):  
Ruhul Amin ◽  
Petla Ramesh Kumar ◽  
Ilias Belharouak
Keyword(s):  
Carbon Nanotubes ◽  
Fuel Cells ◽  
Energy Storage ◽  
Storage Systems ◽  
Electronic Conductivity ◽  
Electrochemical Performances ◽  
Energy Storage Systems ◽  
Energy Storage Devices ◽  
Storage Devices ◽  
Research Fields

Carbon nanotubes (CNTs) are an extraordinary discovery in the area of science and technology. Engineering them properly holds the promise of opening new avenues for future development of many other materials for diverse applications. Carbon nanotubes have open structure and enriched chirality, which enable improvements the properties and performances of other materials when CNTs are incorporated in them. Energy storage systems have been using carbon nanotubes either as an additive to improve electronic conductivity of cathode materials or as an active anode component depending upon structural and morphological specifications. Furthermore, they have also been used directly as the electrode material in supercapacitors and fuel cells. Therefore, CNTs demand a huge importance due to their underlying properties and prospective applications in the energy storage research fields. There are different kinds of carbon nanotubes which have been successfully used in batteries, supercapacitors, fuel cells and other energy storage systems. This chapter focuses on the role of CNTs in the different energy storage and conversion systems and impact of their structure and morphology on the electrochemical performances and storage mechanisms.

Influence of pH on Electrochemical Performances of Iron Phosphate (FePO4•xH2O) Particles and LiFePO4/C Composites

2013 ◽  
Vol 643 ◽  
pp. 100-103 ◽  
Author(s):  
Yi Jie Gu ◽  
Peng Liu ◽  
Yun Bo Chen ◽  
Hong Quan Liu ◽  
Yan Min Wang ◽  
...  
Keyword(s):  
Raw Materials ◽  
Electronic Conductivity ◽  
Iron Phosphate ◽  
Electrochemical Performances ◽  
Galvanostatic Charge ◽  
High Electronic Conductivity ◽  
Electrochemical Capacity ◽  
Size And Morphology ◽  
Co Precipitation ◽  
Influence Of Ph

The effect of pH concentrations on the size and morphology of FePO4•xH2O particles synthesized in a hydrothermal reactor was investigated in this work. FePO4•xH2O was prepared through co-precipitation by employing Fe(NO3)3•9H2Oand H3PO4 as raw materials. The LiFePO4 obtained through lithiation of FePO4•xH2O by using glucose as a reducing agent at 700°C. The electrochemical performance of LiFePO4 powder synthesized at 700°C were evaluated using coin cells by galvanostatic charge/discharge .The results indicated that the synthesized LiFePO4/C composites (pH=2) showed a superior electrochemical capacity of 146 mAh/g and possessed a capacity favorable cycling maintenance at the 0.1C rate and high electronic conductivity.

Electrochemical Performances of Li4-xKXTi5O12 (x=0.02, 0.04, 0.06) as Anode Materials for Lithium Ion Battery

2013 ◽  
Vol 712-715 ◽  
pp. 313-316 ◽  
Author(s):  
Gu Fang
Keyword(s):  
Anode Materials ◽  
Solution Method ◽  
Discharge Rate ◽  
Electronic Conductivity ◽  
Lithium Ion ◽  
Reversible Capacity ◽  
Cycling Performance ◽  
Electrochemical Process ◽  
Electrochemical Performances ◽  
X Ray Diffraction

Li4-xKxTi5O12 (x=0.02, 0.04, 0.06) were prepared via a solution method. The electrochemical performances including charge-discharge, rate property and cyclic voltammety were also investigated. The structure of the samples were characterized by X-ray diffraction. The results revealed that Li3.96K0.04Ti5O12 was well. K+ doping did not change the electrochemical process, instead enhanced the electronic conductivity and ionic conductivity. The reversible capacity and cycling performance were effectively improved.

Effects of Ta Ion Doping on Structure and Electrochemical Performances of Li3V2(PO4)3/C Cathode Materials

2012 ◽  
Vol 519 ◽  
pp. 137-141 ◽  
Author(s):  
Lei Zhang ◽  
Tao Yang ◽  
Qian Yang ◽  
Zhao Hui Huang ◽  
Ming Hao Fang ◽  
...  
Keyword(s):  
Particle Size ◽  
Cathode Materials ◽  
Discharge Rate ◽  
Sol Gel ◽  
Electronic Conductivity ◽  
Physical Structure ◽  
Undoped Sample ◽  
Electrochemical Performances ◽  
Ion Doping ◽  
Method Effects

Ta-doped Li3V2(PO4)3 cathode material coated by carbon was synthesized via a sol-gel method. Effects of Ta5+ doping on the physical structure and electrochemical performances of the Li3V2(PO4)3/C cathode materials were investigated. Compared with the undoped sample, the Ta-doped samples had no excess peaks but the larger particle size and the narrower distribution of the particle size, indicating that Ta5+ entered into the structure of (Li1-5xTax)3V2(PO4)3/C rather than forming any impurities. When x was up to 0.01, the best electrochemical properties of the Ta-doped cathode materials had been displayed at the charge and discharge rate of 0.1C with the voltage of 3.0～4.8V. The analysis of cyclic voltammetry revealed that the polarization of the Li3V2(PO4)3/C cathode materials could be effectively decreased by Ta5+ doping(x=0.01), mainly resulting from the better electronic conductivity.

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