Changxing, China
Changxing, China

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Yi T.-F.,Anhui University of Technology | Yi T.-F.,Chilwee Power Co. | Xie Y.,Heilongjiang University | Zhu Y.-R.,Anhui University of Technology | And 2 more authors.
Journal of Power Sources | Year: 2013

The structural and thermal stability are essential to understand the safety of Li4Ti5O12, but it is not fully understood. Here, the structural and thermal stability were investigated by the density functional theory (DFT) plane-wave pseudopotential technique and experimental method. Sub-micro Li4Ti5O12 particles were synthesized by a solid-state reaction. The calculated results of lattice parameters are highly coincident with the experimental values. XRD and Raman spectra demonstrate the formation of pure phase Li4Ti5O12. There is an amorphous phase and no phase transitionwhen discharged to 0 V, which confirms that there is a certain reversible intercalation processes cycled below 1 V instead of a reductionedecomposition reaction. SEM shows that Li4Ti5O12 powder has a uniform, nearly cubic structural morphology with a narrow size distribution of about 500 nm. The low formation enthalpy (-6061.45±4) indicates that Li4Ti5O12 has a high thermodynamic stability. The superior cycling performance at high rates cycled between 0 and 2.5 shows that Li4Ti5O12 has a very high structural stability. The high thermodynamic stability of Li4Ti5O12 is related to the strong covalent bonding characteristic between Ti and O according to the electron density difference diagram. DSC reveals that PF5 is the main species which damages the SEI layer. © 2012 Elsevier B.V. All rights reserved.


Yi T.-F.,Anhui University of Technology | Yi T.-F.,Harbin Institute of Technology | Yi T.-F.,Chilwee Power Co. | Yin L.-C.,Mudanjiang Normal College | And 5 more authors.
Ceramics International | Year: 2013

Nb-doped LiMn2O4 materials were synthesized by a solid state process, and the structure and kinetic performance were characterized by TG-DTA, XRD, SEM, CV, and EIS. TG-DTA shows that the decomposition reaction has almost completed and all reactions have finished at the temperature of 590 °C. XRD indicates that the all samples are in accordance with the standard spinel LiMn2O4. However, it can be found that little Nb5+ ions do not completely substitute Mn3+ ions of LiMn2-1.667xNbxO4 (x=0.02, 0.03, 0.04). SEM reveals that the average particle size of all samples is about 1 μm. CV exhibits that the improved reversibility and dynamic behaviors of LiMn2O4 can be attributed to the Nb doping. EIS demonstrates that Nb doping decreases the charge transfer resistance of LiMn2O4, and then reduces the cell impedance. Nb doping results in lower electrode polarization and a high lithium ion diffusion coefficient, and can effectively improve the kinetic performance of LiMn 2O4. © 2012 Elsevier Ltd and Techna Group S.r.l.


Yi T.-F.,Anhui University of Technology | Yi T.-F.,Harbin Institute of Technology | Yi T.-F.,Chilwee Power Co. | Yang S.-Y.,Anhui University of Technology | And 4 more authors.
Journal of Power Sources | Year: 2014

The spinel Li4Ti5O12 has been doped by Na for the purpose of improving its cycle performance as an anode. The lattice parameter of Li4Ti5O12 increases due to the Na doping. SEM shows that all materials are well crystallized with a particle size in the range of 400-600 nm. The pristine Li4Ti5O 12 sample has a bigger particle size than that of Na-doped samples. Although the doping does not change the crystallographic structure of Li 4Ti5O12, they exhibit better cyclability at high charge-discharge rate compared with pristine Li4Ti 5O12. Li3.85Na0.15Ti 5O12 gives the best cycling performance, only 11.1% loss of capacity after 80 cycles at 2 C charge-discharge rate. Na-doped Li 4Ti5O12 exhibits lower potential separation, indicating faster electron transfer kinetics and cycling reversibility. Electrochemical impedance spectroscopy demonstrates that the improved performance of the Na-doped Li4Ti5O12 is due to a small decrease in the charge transfer resistance, indicating high electrochemical activity during cycling. The excellent cycling and safety performance of the Na-doped Li4Ti5O12 electrodes are found to be due to the significantly increased ionic and electronic conductivity. Since fast charge-discharge performance is an important factor that needs to be considered in fabricating power batteries in industry, the Na-doped Li4Ti5O12 materials moves closer to real and large scale applications. © 2013 Elsevier B.V. All rights reserved.


Yi T.-F.,Anhui University of Technology | Yi T.-F.,Harbin Institute of Technology | Yi T.-F.,Chilwee Power Co. | Chen B.,Anhui University of Technology | And 3 more authors.
Journal of Power Sources | Year: 2014

The Mo-doped LiNi0.5Mn1.5O4 cathodes are successfully synthesized by citric acid-assisted sol-gel method. The result demonstrates that the Mo-doped LiMn1.4Ni0.55Mo 0.05O4 cathodes present the improved electrochemical performance over pristine LiNi0.5Mn1.5O4. At the 2 C rate after 80 cycles, the discharge capacities are 68.5 mAh g -1 for the pristine LiNi0.5Mn1.5O4 material (53.9% of the capacity at 0.1 C), 107.4 mAh g-1 for the LiMn1.425Ni0.5Mo0.05O4 material (82.1% at 0.1 C), and 122.7 mAh g-1 for the LiMn1.4Ni 0.55Mo0.05O4 material (90.5% at 0.1 C). Mo-doping is favorable for reducing the electrode polarization, suggesting that Mo-doped LiNi0.5Mn1.5O4 electrodes have faster lithium insertion/extraction kinetics during cycling. Mo-doped LiNi 0.5Mn1.5O4 electrodes show lower charge-transfer resistance and higher lithium diffusion coefficients. In addition, LiMn1.4Ni0.55Mo0.05O4 cathode exhibits the smallest particle size, the lowest charge-transfer resistance and the highest lithium diffusion coefficient among all samples, indicating that it has a high reversibility and good rate capability. © 2013 Elsevier B.V. All rights reserved.


Yi T.-F.,Anhui University of Technology | Yi T.-F.,Harbin Institute of Technology | Yi T.-F.,Chilwee Power Co. | Chen B.,Anhui University of Technology | And 4 more authors.
Journal of Alloys and Compounds | Year: 2013

Spinel Li4Ti5-xZrxO 12 (0 ≤ x ≤ 0.25) materials were prepared by a solid-state reaction method using Li2CO3, ZrO2 and TiO 2 as raw material, and the structure and electrochemical performance of the material were investigated by TG-DTA, XRD, SEM, CV, EIS and charge-discharge tests. The Zr-doped Li4Ti5O12 materials show much improved rate capability and specific capacity compared with pristine Li4Ti5O12. Especially, the pristine Li4Ti5O12 offers about 111 mA h g-1, but Li4Ti4.9Zr0.1O12 delivers a remarkable capacity of 172 mA h g-1 at 2 C charge-discharge rate. Li4Ti4.9Zr0.1O12 sample delivers a capacity of 155 mA h g-1 even after 150 cycles at 5 C charge-discharge rates, implying the possibility for high power applications, such as HEV and PHEV. The rate capability of the anode material made from the modified powder is significantly improved when discharged at high current rates due to the reduced charge transfer resistance and fast lithium insertion/extraction kinetics. © 2012 Elsevier B.V. All rights reserved.


Liu B.-S.,Harbin Institute of Technology | Wang Z.-B.,Harbin Institute of Technology | Zhang Y.,Harbin Institute of Technology | Yu F.-D.,Harbin Institute of Technology | And 4 more authors.
Journal of Alloys and Compounds | Year: 2014

Spinel LiMn2O4 has been synthesized by solid state reaction with industrial grade Mn3O4 and Li2CO3 as precursors without purification, and its electrochemical performance for lithium ion battery has been investigated by CR2025 coin cell. The results of X-ray diffraction (XRD) patterns and scanning electron microscope (SEM) images show that the size of LiMn2O4 particles grow up with increasing temperature of calcination, and the sample synthesized at 800°C for 12 h has the best crystallinity with a submicron size. It can deliver initial capacity of 112.9 mA h/g with capacity retention ratio of 89.1% after 200 cycles at charge/discharge rate of 1 C. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) also show that it has the highest electrochemical activity and lowest charge transfer impedance. © 2014 Elsevier B.V. All rights reserved.


Patent
CHILWEE POWER Co. and Beijing University of Chemical Technology | Date: 2014-05-27

Provided is a method for recycling a lead oxide-containing waste material, comprising: (1) contacting the lead oxide-containing waste material with a desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750 C. so as to convert the lead-containing components in the filtration residue into lead oxide; (3) contacting the product obtained from step (2) with an alkaline solution so as to dissolve the PbO therein, and then performing a solid-liquid separation to obtain a PbO-alkaline solution; and (4) crystallizing the PbO-alkaline solution from step (3) to obtain PbO crystals and an alkaline filtrate. The method can reduce the energy consumption.


Patent
CHILWEE POWER Co. and Beijing University of Chemical Technology | Date: 2014-05-27

Provided is a method for directly recovering lead oxide used for a lead-acid battery negative electrode from waste lead paste. The method comprises: (1) contacting waste lead paste with a barium-containing desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; and (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750 C. so as to convert the lead-containing components in the filtration residue into lead oxide. In the method, the direct recovery of a lead oxide raw material applicable to a lead-acid battery negative electrode from waste lead paste is achieved by quantitatively replenishing a barium sulphate additive in the process of desulphuration thereby substantially decreasing the recovery cost and energy consumption, and improving the comprehensive utilization of waste lead paste.


Patent
Chilwee Power Co. and Beijing University of Chemical Technology | Date: 2016-04-27

Provided is a method for recycling a lead oxide-containing waste material, comprising: (1) contacting the lead oxide-containing waste material with a desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750C so as to convert the lead-containing components in the filtration residue into lead oxide; (3) contacting the product obtained from step (2) with an alkaline solution so as to dissolve the PbO therein, and then performing a solid-liquid separation to obtain a PbO-alkaline solution; and (4) crystallizing the PbO-alkaline solution from step (3) to obtain PbO crystals and an alkaline filtrate. The method can reduce the energy consumption.


Patent
Chilwee Power Co. and Beijing University of Chemical Technology | Date: 2016-04-27

Provided is a method for directly recovering lead oxide used for a lead-acid battery negative electrode from waste lead paste. The method comprises: (1) contacting waste lead paste with a barium-containing desulphurizer under desulphurization reaction conditions, and performing a solid-liquid separation on the mixture after contacting to obtain a filtrate and a filtration residue; and (2) performing a conversion reaction on the above-mentioned filtration residue at a temperature of 350-750C so as to convert the lead-containing components in the filtration residue into lead oxide. In the method, the direct recovery of a lead oxide raw material applicable to a lead-acid battery negative electrode from waste lead paste is achieved by quantitatively replenishing a barium sulphate additive in the process of desulphuration, thereby substantially decreasing the recovery cost and energy consumption, and improving the comprehensive utilization of waste lead paste.

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