Crystal structure, solid phase diffusion path and coefficient of Zr-doped Li4Ti5O12

2019 ◽  
Vol 13 (01) ◽  
pp. 1951007
Author(s):  
Zheng Shi ◽  
Shengping Wang ◽  
Qingyun Wei

The influences of the crystal structure of Zr-doped lithium titanate prepared by the sol–gel method on the lithium ion diffusion coefficient and rate performance were studied. Compared with the pure phase Li4Ti5O[Formula: see text], Zr-doped lithium titanate presented a high discharge capacity as well as a good rate performance and cycle performance, and Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] yielded the best electrochemical performance. Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] possessed capacities of 162 (1st) and 143 (100th) mAh g[Formula: see text] at 5[Formula: see text]mA[Formula: see text]cm[Formula: see text] with [Formula: see text]100% of the coulombic efficiency. The area of the migration surface of Li4Ti5O[Formula: see text] is proportional to the square of the lattice constant, so Li4Zr[Formula: see text]Ti[Formula: see text]O[Formula: see text] demonstrated the largest migration surface with 8.3600 Å of “[Formula: see text]”. The larger the migration surface is, the lower the activation energy for lithium ion migration is, and the easier it is for lithium ions to diffuse and migrate.

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 177 ◽  
Author(s):  
Guodong Han ◽  
Xin Wang ◽  
Jia Yao ◽  
Mi Zhang ◽  
Juan Wang

Due to the “shuttle effect”, the cycle performance of lithium sulfur (Li-S) battery is poor and the capacity decays rapidly. Replacing lithium-ion battery is the maximum problem to be overcome. In order to solve this problem, we use a cage like microporous MOF(CPM-5) as a carbon source, which is carbonized at high temperature to get a micro-mesoporous carbon composite material. In addition, indium oxide particles formed during carbonization are deposited on CPM-5 structure, forming a simple core-shell structure CPM-5-C-600. When it is used as the cathode of Li-S battery, the small molecule sulfide can be confined in the micropores, while the existence of large pore size mesopores can provide a channel for the transmission of lithium ions, so as to improve the conductivity of the material and the rate performance of the battery. After 100 cycles, the specific capacity of the battery can be still maintained at 650 mA h·g−1 and the Coulombic efficiency is close to 100%. When the rate goes up to 2 C, the first discharge capacity not only can reach 1400 mA h·g−1, but also still provides 500 mA h·g−1 after 200 cycles, showing excellent rate performance.


Energies ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1946 ◽  
Author(s):  
Hae-Jun Kwon ◽  
Sang-Wook Woo ◽  
Yong-Ju Lee ◽  
Je-Young Kim ◽  
Sung-Man Lee

The electrochemical performance of modified natural graphite (MNG) and artificial graphite (AG) was investigated as a function of electrode density ranging from 1.55 to 1.7 g∙cm−3. The best performance was obtained at 1.55 g∙cm−3 and 1.60 g∙cm−3 for the AG and MNG electrodes, respectively. Both AG, at a density of 1.55 g∙cm−3, and MNG, at a density of 1.60 g∙cm−3, showed quite similar performance with regard to cycling stability and coulombic efficiency during cycling at 30 and 45 °C, while the MNG electrodes at a density of 1.60 g∙cm−3 and 1.7 g∙cm−3 showed better rate performance than the AG electrodes at a density of 1.55 g∙cm−3. The superior rate capability of MNG electrodes can be explained by the following effects: first, their spherical morphology and higher electrode density led to enhanced electrical conductivity. Second, for the MNG sample, favorable electrode tortuosity was retained and thus Li+ transport in the electrode pore was not significantly affected, even at high electrode densities of 1.60 g∙cm−3 and 1.7 g∙cm−3. MNG electrodes also exhibited a similar electrochemical swelling behavior to the AG electrodes.


Author(s):  
Atef Y. Shenouda ◽  
M. M. S. Sanad

Li2NixFe1−xSiO4 (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) samples were prepared by sol–gel process. The crystal structure of prepared samples of Li2NixFe1−xSiO4 was characterized by XRD. The different crystallographic parameters such as crystallite size and lattice cell parameters have been calculated. Scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) investigations were carried out explaining the morphology and function groups of the synthesized samples. Furthermore, electrochemical impedance spectra (EIS) measurements are applied. The obtained results indicated that the highest conductivity is achieved for Li2Ni0.4Fe0.6SiO4 electrode compound. It was observed that Li/Li2Ni0.4Fe0.6SiO4 battery has initial discharge capacity of 164 mAh g−1 at 0.1 C rate. The cycle life performance of all Li2NixFe1−xSiO4 batteries was ranged between 100 and 156 mAh g−1 with coulombic efficiency range between 70.9% and 93.9%.


2003 ◽  
Vol 02 (04n05) ◽  
pp. 299-306 ◽  
Author(s):  
CHIEN-TE HSIEH ◽  
JIN-MING CHEN ◽  
HSIU-WEN HUANG

Nanostructured SnO 2/ C composites used as anode materials were prepared by sol–gel synthesis to explore electrochemical properties in lithium-ion batteries. Surface characteristics of the SnO 2/ C nanocomposite were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that nanocrystalline SnO 2/ C with a grain size of 20–50 nm was uniformly dispersed on the carbon surface. After nanocrytalline SnO 2 coated onto carbon, the discharge capacity showed an increase up to 23%, i.e., from 300 to 370 mAh/g at a current density of 0.6 mA/cm2. The nanocomposite anode can achieve a fairly stable discharge capacity and excellent Coulombic efficiency (>99.5%) over 50 cycles. Cyclic voltammograms indicated that the improvements on capacity and cycleability were due to reversible alloying of nanosized Sn and Li on carbon surface.


RSC Advances ◽  
2015 ◽  
Vol 5 (61) ◽  
pp. 49651-49656 ◽  
Author(s):  
Y. L. Wang ◽  
X. Huang ◽  
F. Li ◽  
J. S. Cao ◽  
S. H. Ye

Pristine LNCM and LNCMA as Li-rich cathode materials for lithium ion batteries were synthesized via a sol–gel route. The Al-substituted LNCM sample exhibits an enhanced high rate performance and superior cyclability.


2018 ◽  
Vol 2018 ◽  
pp. 1-7
Author(s):  
He Wang ◽  
Mingning Chang ◽  
Yonglei Zheng ◽  
Ningning Li ◽  
Siheng Chen ◽  
...  

A lithium-rich manganese-based cathode material, Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2, was prepared using a polyvinyl alcohol (PVA)-auxiliary sol-gel process using MnO2 as a template. The effect of the PVA content (0.0–15.0 wt%) on the electrochemical properties and morphology of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 was investigated. Analysis of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 X-ray diffraction patterns by RIETAN-FP program confirmed the layered α-NaFeO2 structure. The discharge capacity and coulombic efficiency of Li1.25Ni0.2Co0.333Fe0.133Mn0.333O2 in the first cycle were improved with increasing PVA content. In particular, the best material reached a first discharge capacity of 206.0 mAhg−1 and best rate capability (74.8 mAhg−1 at 5 C). Meanwhile, the highest capacity retention was 87.7% for 50 cycles. Finally, electrochemical impedance spectroscopy shows that as the PVA content increases, the charge-transfer resistance decreases.


2019 ◽  
Vol 108 ◽  
pp. 01018
Author(s):  
Danuta Olszewska ◽  
Jakub Niewiedział ◽  
Jakub Boczkowski

Two materials with the stoichiometric composition Li3.85Ni0.15Ti5O12 and Li3.80Cu0.05Ni0.15Ti5O12 were obtained by solid-state reaction using lithium carbonate Li2CO3, titanium oxide TiO2, nickel oxide NiO and copper oxide CuO. The materials were characterized in terms of phase composition, crystal structure as well as cycle performance. Phase composition and crystal structure parameters were determined using X-ray Panalytical Empyrean XRD diffractometer in the range of 10-110° with CuKa radiation. The results were analyzed using Rietveld refinement which was then implemented in the GSAS computer software. The electrochemical properties of the samples were measured by galvanostatic charge/discharge cycles at different rates over a voltage range of 1.0-2.5 V and 0.2-2.5 V. Cyclic voltammetry measurements were also carried out. It was proved that the addition of both Ni and Cu results in high specific capacity of LTO especially at high current rates (2C and 5C). The sample Li3.80Cu0.05Ni0.15Ti5O12 delivers superior capacity above 200 mAh·g -1 when discharged to 0.2 V.


Nanoscale ◽  
2020 ◽  
Vol 12 (32) ◽  
pp. 16901-16909
Author(s):  
Bowen Cong ◽  
Yongyuan Hu ◽  
Shanfu Sun ◽  
Yu Wang ◽  
Bo Wang ◽  
...  

A novel Fe3O4/C@VOx hierarchical nanospindle anode material for LIBs has been successfully designed and fabricated through a MOF-derived route, which delivers high coulombic efficiency, outstanding cycling stability and rate performance.


2019 ◽  
Vol 10 ◽  
pp. 2229-2237
Author(s):  
Li-li Chen ◽  
Hua Yang ◽  
Mao-xiang Jing ◽  
Chong Han ◽  
Fei Chen ◽  
...  

Electrodes with high conductivity and flexibility are crucial to the development of flexible lithium-ion batteries. In this study, three-dimensional (3D) LiFePO4 and Li4Ti5O12 fiber membrane materials were prepared through electrospinning and directly used as self-standing electrodes for lithium-ion batteries. The structure and morphology of the fibers, and the electrochemical performance of the electrodes and the full battery were characterized. The results show that the LiFePO4 and Li4Ti5O12 fiber membrane electrodes exhibit good rate and cycle performance. In particular, the all-fiber-based gel-state battery composed of LiFePO4 and Li4Ti5O12 fiber membrane electrodes can be charged/discharged for 800 cycles at 1C with a retention capacity of more than 100 mAh·g−1 and a coulombic efficiency close to 100%. The good electrochemical performance is attributed to the high electronic and ionic conductivity provided by the 3D network structure of the self-standing electrodes. This design and preparation method for all-fiber-based lithium-ion batteries provides a novel strategy for the development of high-performance flexible batteries.


Nanoscale ◽  
2016 ◽  
Vol 8 (16) ◽  
pp. 8666-8672 ◽  
Author(s):  
Wenwu Li ◽  
Lin Gan ◽  
Kai Guo ◽  
Linbo Ke ◽  
Yaqing Wei ◽  
...  

The well-aligned binary lithium-reactive metal phosphide nanowire arrays were grafted on carbon fabrics. When served as integrated electrodes, they exhibit striking high initial coulombic efficiency, large capacity, excellent rate performance.


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