Advanced Materials Research Vols. 724-725

Abstract: MnO₂/C composites were synthesized in a microwave oven using the activated carbon as a carrier, manganese sulfate as manganese source, ammonium persulfate as an oxidant, ammonium sulfate as conductive agent. The effects of activated carbon and ammonium sulfate concentration on the MnO₂/C composite crystalstructure and assembly of the zinc-air battery were studied. The results show that the mixed crystal MnO₂/C has the best catalytic oxygen reduction effect. The reaction changes from chemical reaction to electrochemical reaction because of activated carbon. The power of MnO₂/C air battery is increased first and then decreased with the active carbon concentration increased. When the carbon concentration was 30gL^-1, the power reaches a maximum value. With the ammonium sulfate concentration increases the battery energy is first increased and then decreased. The power reaches a maximum value as the concentration of ammonium sulfate is 0.25molL^-1.

Abstract: Activated carbon as a supporter, using a redox reaction of MnSO₄žH₂O and KMnO₄, carbon-supported amorphous MnO₂ catalysts were prepared for zinc-air battery positive. Using XRD and specific energy curve, the effects of MnO₂/C and the corresponding zinc-air battery were studied by carbon material type and its amount, concentration of KMnO₄ and the molar ratio of MnSO₄žH₂O and KMnO₄ by XRD. The results show that: Coal activated carbon as carbon supporter, C and MnO₂ mass ratio was 4:3, concentration of KMnO₄ in 27.2g L^-1, molar ratio of KMnO₄ and MnSO₄ žH₂O was 2:3, get the battery performance and economic benefit of the best. Coal activated carbon, C and MnO₂ quality ratio is 4:3, the KMnO₄ concentration 27.2g L^-1, KMnO₄ and MnSO₄žH2O molar ratio of 2:3, best battery of the performance and economic benefits4.

Abstract: As a source of a clean green renewable new energy, wave power generation is paid much attention by more countries while the decrease of the amount of the energy day by day. The conversion technology in the field of wave energy has tended to mature. Now it is running into commercial exploitation leve1. In this paper, the fundamental principles of ocean wave energy generation technology are presented. The classification and present situation of ocean wave power generation device are introduced. At last, some possible directions and prospects of wave energy generation technology are expatiated.

Abstract: Separator shutdown by interrupting the transmission of lithium ions to terminate the battery reaction is a valid safety mechanism for preventing thermal runaway reactions in lithium ion batteries. Yet the cell temperature continues rising after the shutdown, the separator need sufficient thermal stability to physically isolate the electrodes. To reduce the thermal shrinkage of polyethylene (PE) separators, a fresh composite separator is developed by introducing alumina (Al₂O₃) nanoparticles/waterborne polyurethane (WPU) layer on one side of the pristine PE separator via casting process. The microporous structure of the composite separator is supposed to be a significant consideration for the cell performance, which is confirmed by the scanning electron microscope. Compared with the pristine PE separator, the thermal shrinkage of the novel separator improved markedly with an acceptable decline in air permeability and ion conductivity.

Abstract: This paper takes battery cell as research object, presents a new method to estimate the state-of-charge(SOC) of battery, which solves the problem of real-time estimation of power batteries for electric vehicles in the working condition. By a constant current load, periodically measured working voltage of the battery, the remaining time can be calculated using phase-slope based on voltage in the moment, which calculates the battery SOC. The thesis proves the feasibility of that the dynamic work point can be convert to static working point, the relative error of the method is less than 7%. Through software can implement compensation of temperature and aging. The error analysis results show that the method error is small, measurement precision is high.

Abstract: Leaves, which are very easy to obtain freely, can be used as raw materials to prepare carbon materials. In this paper, we found that hard carbon can be prepared from willow leaves by one-step carbonization. When the hard carbon was used as anode materials for Li-ion batteries, the revisable capacity of the hard carbon was 230-260 mAhg^-1 at the current density of 37.2 mAg^-1 with a first-cycle coulombic efficiency of about 50 %. In addition, the hard carbon shows stable cycling performance and good rate capability.

Abstract: The Li₂FeSiO₄/C composite cathode material was synthesized by carbothermal reduction method using Li₂CO₃, Fe₂O₃ and (C₂H₅O) ₄Si and sucrose as raw materials, The prepared samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA) and electrochemical test methods. The influence of sintering temperatures on the electrochemical properties of Li₂FeSiO₄/C was examined. The results indicated that the as-synthetized Li₂FeSiO₄ are orthorhombic structure. The highly pure Li₂FeSiO₄ material with uniform and nanosized particle was synthesized and showed a high specific capacity and good cycle performance by sintering at 600°C for 12h. The initial discharge capacity of Li₂FeSiO₄/C composite cathode material was 140.2 mAh/g at 0.2C rate in a potential range of 1.5-4.7V (vs. Li/Li+) at room temperature, and the discharge capacity was maintained at 141.7 mAh/g after 50 cycles.

Abstract: The LiFePO₄/C cathode material was synthesized by two–step addition of dual carbon sources method based on the in situ polymerization method combining with two–step sintering process. In this study, the structure and morphology have been studied systematically by X–ray diffraction (XRD) and scanning electron microscope (SEM).The electrochemical performances have been shown by the charge/discharge capacity, rate property, cycle performance. It was evidenced that the two–step addition of dual carbon sources had remarkable advantages, including the more complete coating carbon, and the improvement in the electrochemical performance of LiFePO₄/C.

Abstract: Renewable energy resource on islands is rich, which is of unique potential dominance in electricity development. In Taiwan, Green Island power system is a small, isolated system with a load level of 4.39 MW at peak and 0.81 MW at the minimum. It has been mainly fed from diesel generators. This paper is to study the effect of generator outage events on the system transient stability in the Green Island under a high penetration of renewable energy integration. Simulation results reveal that the system stability would not be affected and even improved as long as the renewable energy generators do not trip offline when system contingence occurs. Moreover, addition of one extra generator unit could significantly reduce the drop of the system's transient frequency. The work can provide several important operational experience to isolated micro grids with high penetration of renewable energy.

Abstract: In order to stabilize fluctuations caused by intermittent energy and complement different storage elements advantages, we designed a hybrid energy storage combining VRB pack with EDLC bank. This hybrid energy storage device has two DC/DC convertors; DC/DC(A) controls VRB pack's power and DC/DC(B) stabilizes the voltage on DC bus. By doing this, it is easy to make power schedule for VRB according to renewable energy forecast and SOC of battery, while EDCL bank stabilizes the short-time power fluctuation, most of which result from forecasting error. To achieve the above goals, self-adaptive PID controller based on BP neuron network is applied in DCDC(B), for switching-mode convertor is strongly non-linear system and traditional PID controller is not suitable to the case of large changed load. Simulations in Matlab Simulink are presented to testify the novel control method and show this hybrid energy storage device can work efficiently.