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Cheng C.L.,University of Shanghai for Science and Technology | Liu H.J.,Shanghai University | Xue X.,Shanghai University | Cao H.,Shanghai Aerospace Power Technology Co. | And 2 more authors.
Advanced Materials Research | Year: 2014

Li4Ti5O12/Ce nanoparticles are synthesized through hydrothermal method. The structure and morphology characteristics of the composite are investigated by XRD, SEM. Meanwhile, electrochemical properties were analyzed through charging-discharging test. The prepared Li4Ti5O12/Ce nanoparticles have good rate performance and cycling performance. It exhibited discharging capacity of 128.0 mAh/g at a high rate of 10 C. It promises to be advanced batteries with high energy density and long cycle life. © (2014) Trans Tech Publications, Switzerland.

Cheng C.,University of Shanghai for Science and Technology | Liu H.,Shanghai University | Xue X.,Shanghai University | Cao S.,University of Shanghai for Science and Technology | And 3 more authors.
RSC Advances | Year: 2014

In this paper, we developed a novel strategy to synthesize nano-sized Li4Ti5O12 (LTO) by hydrothermal method and calcination. X-ray diffraction and high resolution transmission electron microscopy were performed to characterize the structures and morphologies of these samples. Highly crystalline and pure-phase Li4Ti5O12 synthesized at low calcination temperature of 500 °C has been reported for the first time. This nanocrystalline LTO was tested as the anode material for lithium ion batteries, and exhibited excellent reversible capacities of 166, 162, 155, 142 and 123 mAh g-1 at current densities of 1 C, 2 C, 5 C, 10 C and 20 C, respectively. It also demonstrated good capacity retention and high coulombic efficiency values at all current rates. This excellent electrochemical performance makes our LTO a promising anode material for high energy/power density lithium ion batteries. This journal is © The Royal Society of Chemistry.

Cheng C.,University of Shanghai for Science and Technology | Liu H.,Shanghai University | Li J.,Jilin University | Xue X.,Shanghai University | And 4 more authors.
Journal of Power Sources | Year: 2015

The present work demonstrates that lithium ions can be stepwise substituted by protons from spinel Li4Ti5O12 crystalline particles though simple ion-exchange in aqueous HCl solution with the aid of heat treatment. This enables us to continuously tune the Li-to-Ti stoichiometric ratios from 0.80 to 0.59, 0.41, 0.21, 0.15, and 0.09, thus transforming Li4Ti5O12 to Li4-xTi5O12 nanocrystals. The resulting nanocrystals maintain the spinel crystal structure when x becomes smaller than 3. Among as-prepared the Li4-xTi5O12 crystalline particles, Li1Ti5O12 shows the highest capacity of 193 mAh g-1 at 1C and 148 mAh g-1 at 20C, lower current impedance (47 Ω), significantly improved rate capability and fairly long cycle life. This excellent electrochemical performance makes spinel Li4-xTi5O12 particles as a promising anode candidate for lithium ion batteries superior. © 2015 Elsevier B.V.

Shi S.,Shanghai Aerospace Power Technology Co. | Wu Y.,Donghua University | Lai P.,Shanghai Aerospace Power Technology Co. | Jiang X.,Shanghai Aerospace Power Technology Co. | Xie J.,Shanghai Aerospace Power Technology Co.
EVS 2010 - Sustainable Mobility Revolution: 25th World Battery, Hybrid and Fuel Cell Electric Vehicle Symposium and Exhibition | Year: 2010

A large scale lithium-ion battery system of SAPT EIFP326V50Ah for Electric vehicles (EV) has been developed. This system is composed of 9 modules and each module is made up of 24 cells. As the maximum constant discharge power of the battery is up to 48kW, the pack temperature would rise dramatically during fast charging and discharging process. So an effective water cooling system was developed for the pack. Before the cooling system was used, the maximum temperature of battery pack, whose initial temperature was 25 °C, would rise up to about 50°C after 3C (150A) fast charging. The temperature non-uniformity was about 12°C. When the water cooling system was used, the temperature will be reduced to 40°C, with only 6 Celsius degrees' temperature non-uniformity inside the pack. To better study the heat dissipation of the EIFP system, a three-dimensional thermal model was developed to simulate the pack's temperature distribution. This numerical model was performed at different charging and discharging current rates, operating temperatures and different water cycling velocity.

Jiang Y.,Shanghai University | Liu R.,Shanghai University | Xu W.,Shanghai University | Jiao Z.,Shanghai University | And 6 more authors.
Journal of Materials Research | Year: 2013

A novel graphene-modified LiMnPO4 composite as a performance-improved cathode material for lithium-ion batteries has been prepared with LiH2PO4, Mn(CH3COO) 2·4H2O, and graphite oxide (GO) suspension by spray-drying method. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and galvanostatic charge-discharge tests are applied to characterize these materials. The structure analysis shows that LiMnPO4 sheets with width of 100-200 nm and thickness of 20-30 nm are attached to the graphene sheets in pieces. The graphene sheets with good electrical conductivity serve as a conducting network for fast electron transfer between the active materials and charge collector, as well as buffered spaces to accommodate the volume expansion/contraction during the discharge/charge process. The electrochemical tests show that the composite cathode material could deliver a capacity of 105.1 mAh/g at 0.05 C in the voltage range of 2.5-4.4 V. Moreover, the cells showed fair good cycle ability over 50 cycles. © 2013 Materials Research Society.

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