Shanghai Electrochemical Energy Devices Research Center

Shanghai, China

Shanghai Electrochemical Energy Devices Research Center

Shanghai, China
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Huang J.,Shanghai JiaoTong University | Yang K.,Shanghai JiaoTong University | Zhang Z.,Shanghai JiaoTong University | Zhang Z.,Shanghai Electrochemical Energy Devices Research Center | And 3 more authors.
Chemical Communications | Year: 2017

∼1 V lithium intercalation materials are promising anodes for lithium-ion batteries, because such materials give consideration to both the tolerance of lithium plating (e.g., graphite with ∼0.1 V versus Li+/Li easily results in lithium plating due to a too low potential) and the energy density of the batteries (e.g., Li4Ti5O12 with ∼1.55 V decreases the battery voltage, and thus reduces the energy density). Herein, the layered perovskite compound LiEuTiO4 with a 0.8 V lithium intercalation/deintercalation potential plateau was successfully synthesized by the ion-exchange reaction with NaEuTiO4 prepared via a sol-gel method. LiEuTiO4 can deliver a high capacity of 219.2 mA h g-1 (2nd discharge) at a rate of 100 mA g-1. Even after 500 cycles, the discharge capacity remains at ∼217 mA h g-1 and the Coulombic efficiency is 99.2%. To our knowledge, the cycle stability of LiEuTiO4 exceeds all previous ∼1 V electrodes. Different from the common lithium intercalation Ti-based electrodes (such as Li4Ti5O12) based on the reduction of the Ti4+ to Ti3+, electrochemical lithium intercalation into LiEuTiO4 leads to the reduction of the Eu3+ to Eu2+. © The Royal Society of Chemistry 2017.


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 Alloys and Compounds | Year: 2017

Li-rich layered oxides, one of the most promising cathodes for high energy Li-ion batteries, commonly undergo some issues such as poor rate performance, low Coulombic efficiency, voltage degradation and so on. In this work, Li1.18Mn0.56Ni0.13Co0.13O2 cathodes with excellent rate capability and cycling stability are prepared by a new molten-salt method using KCl and NaCl as complex flux. The electrochemical tests show that these cathodes can deliver an initial discharge specific capacity of 224.3 mA h g−1 at 300 mA g−1. Meanwhile, the capacity retention ratio remains 92.1% after 100 cycles. The outstanding electrochemical performance is mainly attributed to the uniform distribution of TM-elements in Li1.18Mn0.56Ni0.13Co0.13O2 cathodes, which can promote the electrochemical activation of Li2MnO3-like component. Especially, it is found that the uniformity of TM elements in Li-rich cathodes can be improved by choosing molten-salt method as the synthetic strategy. © 2017


Luo D.,Shanghai JiaoTong University | Shi P.,Shanghai JiaoTong University | Fang S.,Shanghai JiaoTong University | Fang S.,Shanghai Electrochemical Energy Devices Research Center | And 4 more authors.
Inorganic Chemistry Frontiers | Year: 2017

Assembled microspherical cathodes have attracted great attention thanks to their high tap density, good rate capability and cycling stability. However, for layered Li-rich transition-metal oxides (LROs), the preparation of uniformly assembled microspheres still faces many challenges due to harsh synthetic conditions and the nature of multiple metal elements. In this work, Li1.17Mn0.50Ni0.16Co0.17O2 assembled microspheres have been prepared by a new route tactfully combining a solvothermal process and a molten-salt method. The use of a solvothermal process is helpful for the preparation of precursors with assembled microspherical morphology, and the addition of complex salts (NaCl and KCl), can increase the uniformity of cation distribution. The product obtained at 800 °C delivers the best electrochemical performances among all samples. At a current density of 300 mA g-1, its initial discharge capacity is larger than 228 mA h g-1, corresponding to a capacity retention ratio of 86.8% after 200 cycles. Even if the current density increases to 2000 mA g-1, its discharge capacity is still as large as 156 mA h g-1. What's more, we discover the moving rate of Li-ions during the sintering process will affect the uniformity of Li2MnO3-like and LiMO2 components in LRO assembled microspheres. This discovery is helpful for the preparation of LRO assembled microspheres with excellent electrochemical performances. © The Partner Organisations.


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.


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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