Shanghai Electrochemical Energy Devices Research Center

Shanghai, China

Shanghai Electrochemical Energy Devices Research Center

Shanghai, China

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Liu Y.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | Luo D.,Shanghai JiaoTong University | And 3 more authors.
Journal of the Electrochemical Society | Year: 2016

New mixtures of triethylene glycol dimethylether, fluoroethylene carbonate and non-flammable methyl-nonafluorobutyl ether were introduced as safe electrolytes for lithium-ion batteries. It was discovered that only 10 wt% methyl-nonafluorobutyl ether was enough to ensure high safety of electrolyte and better wettability to electrodes and separator than the conventional electrolyte. The conductivity of these ternary electrolytes could reach 4.8 mS cm-1 at 25° C. Graphite/LiFePO4 coin cells with commercial electrodes were used to evaluate the electrochemical performances, and this kind of safe electrolytes could exhibit better rate and cycle performances than the conventional electrolyte. These results suggested that such ternary electrolytes composed of non-flammable hydrofluoroethers and solvents with high flash point had a great potential for practical application. © 2016 The Electrochemical Society. All rights reserved.


Liu Y.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | Shi P.,Shanghai JiaoTong University | And 4 more authors.
Journal of Power Sources | Year: 2016

New mixtures of 3-(2-methoxyethoxy)propanenitrile, fluoroethylene carbonate and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether are introduced as safe electrolytes for lithium-ion batteries. The electrolytes with 30 wt% 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether can own high safety and better wettability to separator and electrodes than the conventional electrolyte. The oxidation potentials of these electrolytes are about 4.8 V versus Li/Li+, and their conductivity can reach 5.42 mS cm−1 at 25 °C. Graphite/LiMn2O4 coin cells are used to evaluate the electrochemical performances, and this kind of safe electrolytes can exhibit better rate and cycle performances than the conventional electrolyte. These results indicate that such ternary electrolytes have a great potential for practical application. © 2016 Elsevier B.V.


Li X.,Shanghai JiaoTong University | Zhang Z.,Shanghai JiaoTong University | Zhang Z.,Shanghai Electrochemical Energy Devices Research Center | Li S.,Shanghai JiaoTong University | And 3 more authors.
Journal of Power Sources | Year: 2016

In this work, composite polymer electrolytes (CPEs), that is, 80%[(1-x)PIL-(x)SN]-20%LiTFSI, are successfully prepared by using a pyrrolidinium-based polymeric ionic liquid (P(DADMA)TFSI) as a polymer host, succinonitrile (SN) as a plastic crystal, and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as a lithium salt. XRD and DSC measurements confirm that the as-obtained CPEs have amorphous structures. The 80%[50%PIL-50%SN]-20%LiTFSI (50% SN) electrolyte reveals a high room temperature ionic conductivity of 5.74 × 10-4 S cm-1, a wide electrochemical window of 5.5 V, as well as good mechanical strength with a Young's modulus of 4.9 MPa. Li/LiFePO4 cells assembled with the 50% SN electrolyte at 0.1C rate can deliver a discharge capacity of about 150 mAh g-1 at 25°C, with excellent capacity retention. Furthermore, such cells are able to achieve stable discharge capacities of 131.8 and 121.2 mAh g-1 at 0.5C and 1.0C rate, respectively. The impressive findings demonstrate that the electrolyte system prepared in this work has great potential for application in lithium ion batteries. © 2016 Elsevier B.V. All rights reserved.


Luo D.,Shanghai JiaoTong University | Wang G.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Yang L.,Shanghai JiaoTong University | And 2 more authors.
Electrochimica Acta | Year: 2016

In this work, Li1.15Mn0.49Ni0.18Co0.18O2 nanoplates with exposed (012) facet are prepared for the first time by co-precipitation method under the assistance of cetyltrimethyl ammonium bromide. As cathode materials of lithium-ion batteries, the Li1.15Mn0.49Ni0.18Co0.18O2 nanoplates can deliver the initial discharge capacities of 219.8 and 192 mA h g−1 at 300 and 700 mA g−1, respectively. It suggests the Li1.15Mn0.49Ni0.18Co0.18O2 nanoplates possess an excellent rate capability. After 200 cycles, the capacity retention ratio at 700 mA g−1 is still as large as 82.6%. The superior rate capability can be attributed to the shorter transport distance of lithium ions in these nanoplates with exposed (012) facet. The above results also indicate that the electrochemical performances of Li-rich layered oxides can be improved by allocating proper facets. © 2016


Tian Q.,Shanghai JiaoTong University | Luo D.,Shanghai JiaoTong University | Li X.,Shanghai JiaoTong University | Zhang Z.,Shanghai JiaoTong University | And 4 more authors.
Journal of Power Sources | Year: 2016

Titanium dioxide (TiO2) has been considered to be a promisingly alternative anode material for lithium-ion batteries and thus attracted wide research interest. But, its practical application in lithium-ion batteries is seriously impeded by low capacity and poor rate capability. In the present work, the electrochemical performance of TiO2 is significantly improved by elaborately fabricating hierarchical structures. These as-prepared four hierarchical structure TiO2 assembled by different building blocks (TO2-2 h, TO2-6 h, TO2-18 h and TO2-24 h) all exhibit impressed performance. More importantly, the TO2-6 h constructed by curved nanosheets exhibits the best performance, delivering a capacity of 231.6 mAh g-1 at 0.2C after 200 cycles, and capacities of 187.1 and 129.3 mAh g-1 at 1 and 10C after even 1200 cycles, respectively. The results indicated that design and fabrication of hierarchical structure is an effective strategy for significantly improving the electrochemical performance of TiO2 electrodes, and the electrochemical performance of hierarchical structure TiO2 is heavily dependent on its building blocks. It is suggested that thus excellent electrochemical performance may make TiO2-6 h a promising anode material for advanced lithium-ion batteries with high capacity, good rate capability and long life. © 2016 Elsevier B.V. All rights reserved.


Qu L.,Shanghai JiaoTong University | Luo D.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | And 5 more authors.
Journal of Power Sources | Year: 2016

Mg-doped Li2FeSiO4/C is synthesized by using Fe2O3 nanoparticle as iron source. Through Rietveld refinement of X-ray diffraction data, it is confirmed that Mg-doped Li2FeSiO4 owns monoclinic P21/n structure and Mg occupies in Fe site in the lattice. Through energy dispersive X-ray measurement, it is detected that Mg element is distributed homogenously in the resulting product. The results of transmission electron microscopy measurement reveal that the effect of Mg-doping on Li2FeSiO4 crystallite size is not obvious. As a cathode material for lithium-ion battery, this Mg-doped Li2FeSiO4/C delivers high discharge capacity of 190 mAh g-1 (the capacity was with respect to the mass of Li2FeSiO4) at 0.1C and its capacity retention of 100 charge-discharge cycles reaches 96% at 0.1C. By the analysis of electrochemical impedance spectroscopy, it is concluded that Mg-doping can help to decrease the charge-transfer resistance and increase the Li+ diffusion capability. © 2016 Published by Elsevier B.V.


Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | Wang G.,Shanghai JiaoTong University | Qu L.,Shanghai JiaoTong University | And 4 more authors.
Journal of Materials Chemistry A | Year: 2015

A mixture of diethylene glycol diethylether and non-flammable methyl-nonafluorobutyl ether was introduced as a new electrolyte for lithium ion batteries. And a fluoroethylene carbonate additive was used in this electrolyte to improve the compatibility with the graphite anode. The non-flammability and high flash point of this electrolyte indicated its high safety. This electrolyte had low viscosity and its conductivity reached 3.8 mS cm-1 at 25°C. Graphite/LiFePO4 coin cells with commercial electrodes were utilized to evaluate the performances of the electrolyte. The rate, cycle and lowerature performances of the graphite/LiFePO4 cells using this electrolyte were close to those of the cells using the conventional electrolytes with and without the fluoroethylene carbonate additive. These results indicated that this kind of safe electrolyte based on non-flammable hydrofluoroethers and solvents with a high flash point has great potential for practical application. © 2015 Royal Society of Chemistry.


Wang G.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | Luo D.,Shanghai JiaoTong University | And 3 more authors.
Electrochemistry Communications | Year: 2016

Neat ionic liquid electrolytes based on functionalized 1,3-dialkylimidazolium cation and bis(fluorosulfonyl)imide anion were investigated in MCMB/LiFePO4 full cells with commercial electrodes for the first time. Ether functionalization could bring the prominent improvement of initial efficiency and the comparable cycle performance to a conventional carbonate-based electrolyte. In view of full cells, it was inferred that the further oxidation on cathode of the reduction products on anode during the charge process might result in the serious capacity loss of initial cycle. © 2016 Elsevier B.V.


Luo D.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | Yang L.,Shanghai JiaoTong University | And 2 more authors.
Journal of Materials Chemistry A | Year: 2016

As promising cathodes for high-energy Li-ion batteries, the commercial application of layered Li-rich transition-metal oxides (LROs) is significantly prevented by their non-ideal cycling stability and rate capability. In this work, Li1.23Mn0.46Ni0.15Co0.16O2 samples are prepared by combining a solvothermal process and a Li2CO3 molten-salt method. When the molar ratio of Li2CO3 to transition-metal ions is 4 : 1, the obtained sample has the best electrochemical performance. Its initial discharge capacities at 20 and 300 mA g-1 are larger than 307.8 and 232.2 mA h g-1, respectively. After 200 cycles, the capacity retention ratio at 300 mA g-1 is still as large as 85.3%. In addition, we discovered that the relative content of lithium on the particle surface of the samples is more than that in the particle interior, and this distribution behavior of lithium is adjustable. In particular, we demonstrate for the first time that the overmuch enrichment of lithium on the particle surface will hinder the diffusion of Li-ions. This is the blockade effect of surface lithium, and this blockade effect can be alleviated by the Li2CO3 molten-salt method. This is the reason that the electrochemical performance of LROs can be greatly improved by the Li2CO3 molten-salt method. © The Royal Society of Chemistry 2016.


Li X.,Shanghai JiaoTong University | Li S.,Shanghai JiaoTong University | Zhang Z.,Shanghai JiaoTong University | Zhang Z.,Shanghai Electrochemical Energy Devices Research Center | And 4 more authors.
Journal of Materials Chemistry A | Year: 2016

In this work, a new class of high-performance polymeric ionic liquid-silica hybrid ionogel electrolytes (HIGEs) is developed by a nonaqueous sol-gel route, in which LiTFSI-ionic liquid as the ion conducting phase is immobilized with a hybrid pyrrolidinium-based polymeric ionic liquid and silica matrix. The thermal and electrochemical properties of these HIGEs as well as their application in lithium metal batteries (LMBs) are investigated. It is found that HIGEs reveal excellent thermal stability, good room temperature ionic conductivity, high electrochemical stability, a suitable lithium ion transference number, and potential to suppress Li dendrite formation. In particular, Li/LiFePO4 cells with the as-obtained HIGE at 0.2C rate can deliver a discharge capacity of about 150 mA h g-1 at 25 °C, with excellent capacity retention. Moreover, at 0.5C, 1.0C, and 2.0C, the stable discharge capacities are as high as 138.1 mA h g-1, 120.3 mA h g-1 and 73.8 mA h g-1, respectively. The desirable battery performance can be attributed to the good electrochemical properties of HIGEs and interfacial compatibility between HIGEs and electrodes. These findings show that HIGEs prepared in this work have great potential for application as safe electrolytes in LMBs. © 2016 The Royal Society of Chemistry.

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