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Lin X.,South China University of Technology | Zhao Y.,South China University of Technology | Zhao Y.,Guangdong Higher Education Institute | Kuang Q.,South China University of Technology | And 4 more authors.
Solid State Ionics | Year: 2014

A series of Co-doped Li9V3 - xCox(P 2O7)3(PO4)2/C (x = 0.00-0.10) compounds have been prepared by sol-gel method and the Rietveld refinement results indicate that pure-phase Li9V 3 - xCox(P2O7)3(PO 4)2/C (x = 0.00-0.10) compounds with trigonal structure can be obtained. Their electrochemical performance has been investigated and the results show that, although the initial specific capacity decreased with Co doping at a lower current rate, both cycle performance and rate capability have excited improvement with proper Co-doping content. Li9V 2.96Co0.04(P2O7)3(PO 4)2/C compound presents the best cyclic ability and rate performance. The enhancement of cyclic ability and rate performance may be attributed to enhanced specific surface area and improved lithium-ion diffusion during the proper amount of Co-doping (x = 0.04) in V sites. © 2014 Elsevier B.V. Source


Lin X.,South China University of Technology | Zhao Y.,South China University of Technology | Zhao Y.,Guangdong Higher Education Institute | Yan D.,South China University of Technology | And 3 more authors.
Electrochimica Acta | Year: 2016

In this paper, we have prepared the carbon-coated Li9V3(P2O7)3(PO4)2 (LVPP/C) composite via a simple carbon thermal reduction and its lithium inserted-extracted mechanism are systematically investigated. LVPP/C cathode can keep a reversible capacity of 100.6 mAhg-1, 98.7% of the initial discharge capacity, after 50 cycles within 2.5 V-4.6 V, while an obviously capacity-fading is observed within 2.5 V-4.8 V. Meanwhile, the LVPP/C anode delivers a well rate capability and, a reversible capacity of 94.5 mAhg-1 (1.0-2.5 V) can still be retained after 60 cycles, ranging from 0.1C to 2C and finally in 0.1C succession. A good preservation of the LVPP structure is observed during the discharge-charge process by in-situ XRD and an intercalation reaction mechanism is also confirmed for LVPP/C anode here for the first time. At last, a novel symmetrical full battery by using LVPP/C as both cathode and anode simultaneously has been successfully assembled. The investigation shows that this symmetrical cell, with an average voltage of 2.5 V, can deliver a reversible capacity of 59.8 mAhg-1 after 30 cycles at 0.1C. © 2016 Elsevier Ltd. All rights reserved. Source


Liang Z.,South China University of Technology | Zhao Y.,South China University of Technology | Zhao Y.,Guangdong Higher Education Institute | Ouyang L.,South China University of Technology | And 5 more authors.
Journal of Power Sources | Year: 2014

Carbon-coated Li3VO4 sample is synthesized by a simple sol-gel method. X-ray diffraction and X-ray photoelectron spectroscopy results show that single-phase Li3VO4 can be obtained in a reducing atmosphere with the valence of vanadium of +5. The final product sintered at 650 C demonstrates a favorable electronic conductivity with 6.12% residual carbon. Electrochemical testing shows that the carbon-coated Li 3VO4 sample display a discharge capacity of 662.6 mAh g-1 and 507.4 mAh g-1 at 0.18C in the first and the second cycle, respectively, and a reversible capacity (charge capacity) of ∼480.0 mAh g-1 can be obtained in the second cycle. Furthermore, the discharge-charge capacity of the sample can retain ∼180 mAh g-1 and ∼90 mAh g-1 at 12C and 40C, respectively. © 2013 Elsevier B.V. All rights reserved. Source


Zeng J.,South China University of Technology | Zhao Y.,South China University of Technology | Zhao Y.,Guangdong Higher Education Institute | Liang Z.,South China University of Technology | And 2 more authors.
Journal of Solid State Electrochemistry | Year: 2014

A series of Ti4+-doped Li9V3 - x Ti x (P2O7)3(PO4) 2/C compounds have been prepared by using wet method. X-ray diffraction measurement shows that single phase region can be expressed as x ≤ 0.10. The effects of substitution of Ti for V on the electrochemical properties of Li9V3 - x Ti x (P 2O7)3(PO4)2 compounds have been studied. Our investigations show that Ti doping can improve the electrochemical performance. The Li9V2.95Ti 0.05(P2O7)3(PO4) 2/C exhibits the best cycle performance and the highest first discharge capacity of 120.7 mAh g-1 at 0.2 C. The electrochemical impedance spectroscopy indicates that the charge transfer resistance initially decreases with x and then for x > 0.05 increases monotonically with Ti 4+ content. © 2013 Springer-Verlag Berlin Heidelberg. Source


Wang S.E.,Jinan University | Wang S.E.,Guangdong Higher Education Institute | Zhu S.Q.,Jinan University | Chen Z.Q.,Jinan University | And 3 more authors.
Journal of Russian Laser Research | Year: 2013

We design a passively Q-switched intracavity frequency-doubled 532 nm laser using Nd:YAG/Cr4+:YAG composite crystal and type II phase matching KTP crystal. Under 13. 97 W pump power, the average output power of the laser elaborated is up to 681 mW, with 200 ns pulse width and 9. 1 kHz pulse repetition rate. © 2013 Springer Science+Business Media New York. Source

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