Discharge Platforms Research Articles

Synthesis of xLiVPO4F·yLi3V2(PO4)3/C composite as a potential cathode material for Li-ion batteries

xLiVPO4F·yLi3V2(PO4)3/C cathode materials are prepared by a two-step carbon coating method. XRD results show that all the xLiVPO4F·yLi3V2(PO4)3/C composites (x:y ≠ 0) contain both LiVPO4F and Li3V2(PO4)3 phases, and no impurities are detected. SEM results show that the average primary size of the composites is 0.3–1 μm. All the composites show less aggregation than the single LiVPO4F/C and Li3V2(PO4)3/C samples. Electrochemical measurements show that the composites have better electrochemical performance than LiVPO4F/C. Among all the composites, 2LiVPO4F·Li3V2(PO4)3/C shows the optimal electrochemical properties. The sample possesses the specific capacities of 143.9 and 112.6 mAh g−1 at 0.1 C and 2 C rates, respectively, and shows flat discharge platforms around 4.2, 4.1, 3.7, and 3.6 V under low current rate. The sample also exhibits good cycle performance.

Novel synthesis of LiCoPO4–Li3V2(PO4)3 composite cathode material for Li-ion batteries

LiCoPO4–Li3V2(PO4)3 composite cathode material is synthesized by a chemical lithiation method, with Co3V2O8 as the precursor and oxalic acid as the reductant. XRD result indicates that the composite is composed of olivine-type LiCoPO4 and monoclinic Li3V2(PO4)3. TEM, HRTEM and FFT results show that the LiCoPO4–Li3V2(PO4)3 particles are wrapped with nano-carbon webs, and the crystal particles contain the lattice fringes and diffraction spots of LiCoPO4 and Li3V2(PO4)3. The composite shows the stepped charge–discharge platforms which contain the potential plateaus of LiCoPO4 (~4.8V) and Li3V2(PO4)3 (~3.6, 3.7, 4.1 and 4.5V). During the potential range of 3.0–5.0V, the composite delivers the specific capacities of 163.7, 133.6 and 93.8mAhg−1 at 0.05, 0.5 and 2C rates, respectively, and shows good cycling performance.

Fabrication of anode materials for a lithium-ion battery with waste semi-coke carbon powder

Waste semi-coke powder generated in semi-coke production and transportation was doped with 8 mass% boron by a high temperature treatment at 2300 °C. Results indicate that the doping overcomes the shortcomings of low coulombic efficiency, short cycle life, and there are no charge and discharge platforms due to a high content (15 mass%) of impurity in the raw materials. The first discharge capacity is 361 mAh/g at a rate of 0.1 C and the reversible capacity is 314 mAh/g after 300 cycles at charge and discharge rates of 1 C, showing excellent cycling performance. [New Carbon Materials 2014, 29(6): 503–507]

Changing of SEI Film and Electrochemical Properties about MCMB Electrodes during Long-Term Charge/Discharge Cycles

The reasons for the capacity loss of mesocarbon microbead (MCMB) in lithium ion cells during long-term charge-discharge cycles were evaluated in this paper. The MCMB electrodes were charged and discharged for 2000, 2500 and 3000 cycles after activation. Solid electrolyte interphase (SEI) film was deposited on the surface of MCMB particles after activation. The contents of O and F in SEI film tended to increase continuously. Li2O was generated firstly, then LiF was produced later and the content of LiF increased with the cycles proceeding. During the cycles, the voltage differences between charge and discharge platforms increased gradually and the specific capacity decreased. The cell resistances increased continuously and the peak currents of intercalation/de-intercalation reactions in cyclic voltammetry curves were reduced. The decline of electrochemical properties was related to both the growth of SEI films and the consumption of electrolyte salt LiPF6.

An RFID Bulk Cargo Supervising System

In this work, a system using active RFID tags to supervise truck bulk cargo is described. The tags are attached to the bodies of the trucks and readers are distributed in the cargo buildings and attached to weighs and the discharge platforms. PDAs with camera and support to a WiFi network are provided to the inspectors and access points are installed throughout the discharge area to allow effective confirmations of unload actions and the acquisition of pictures for future audit. Broadband radio equipments are used to establish efficient communication links between the weighs and cargo buildings which are usually located very far from each other in the field. A Web application software was especially developed to enable robust communication between the equipments for efficient device management, data processing and reports generation to the operating personal. The system was deployed in a cargo station of a Brazilian seashore port. The obtained results prove the effectiveness of the proposed system.