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The capacity and power loss are usually observed when lithium ion batteries were cycled or stored, however, the degradation mechanisms and their correlation with cell performance fade are not only dependent on the cell chemistry but also on the cell design and manufacture technique. The capacity loss diagnosis and the lifetime prediction for LIBs are still critical issues for large format applications. Commercial 18650 lithium ion cells containing a composite cathode of LiNi0.5Mn0.3Co0.2 (NMC) and LiMn2O4 (LMO) and graphite anode with a nominal capacity of 2.15 Ah were used in this study. Although the aging behavior of the battery comprised with LiNi1/3Mn1/3Co1/3O2/LiMn2O4 composite cathode and graphite anode cycled between 4.2 and 2.8V had been studied with an incremental capacity technique and suggested that there are two stages of capacity fade with first stage mainly caused by the loss of inventory (LLI) and further suffered from loss of active material (LAM) in positive electrode in the second stage [1, 2]. The results of capacity retention study within the voltag e range between 4.2 and 2.75V by following the manufacturer’s suggestion and charging the cells with CC-CV mode with 0.5C rate (cut-off at 0.04C) and discharging at 0.5, 1.0, and 2.0C rates, respectively, shown in Fig.1 (a), manifest that the cells cycled at higher discharge rate exhibit longer cycle life than that cycled at 0.5C. It is contrary to the generally accepted notion that high C-rate will accelerate cell aging. However, the expected tendency can be observed when cells were cycled between 4.2 and 3.0V (Fig. 1 (b)). From the results incremental capacity analysis (ICA) for the charge/discharge curves of the cells discharged at 1.0C rate with lower cut-off voltage of 2.75 and 3.0V, respectively, the redox peaks at around 3.53V, those relates with the amount of active graphite, decreases abruptly after 300th cycle where the accelerated capacity fade occurs for cell cycled between 4.2 and 2.75V.That suggests the accelerated capacity loss can be caused by loss of anode material instead of cathode material in additional to the continued loss of lithium inventory that can be observed from the shifting of the peak at around 3.53V to higher voltage and lowering of the peak at about 3.69V (Fig. 2). In order to understand the non-linear capacity fade when cells were cycled between 4.2 and 2.75V, post-mortem studies with XRD, SEM, ICP, and capacity retention for the electrodes obtained from fresh, 200 cycled, and aged cells will be performed for comparison with those of the cells cycled within 4.2 and 3.0V to support the results obtained from ICA. Reference [1] M. Dubarry, C. Truchot, M. Cugnet, B.Y. Liaw, K. Gering, S. Sazhin, D. Jamison, C. Michelbacher, Journal of Power Sources, 196 (2011) 10328-10335. [2] M. Dubarry, C. Truchot, B.Y. Liaw, K. Gering, S. Sazhin, D. Jamison, C. Michelbacher, Journal of Power Sources, 196 (2011) 10336-10343. Figure 1

In this study, the capacities and electrochemical impedances at various states of charge (SOC) are measured after the screened commercial 18650 lithium ion cells assembled with composite cathode of layered mixed oxide (NMC) and spinel lithium manganite (LMO) and graphite anode were stored at various states of depth-of-discharge (DOD) at various temperatures for various durations. The results manifest that the capacity fading is strongly affected by the storage temperature and becomes prominent at temperatures higher than 45oC. Incremental capacity analyses (ICA) for the charge/discharge curves before and after storage were performed for the qualitative mechanism study. It demonstrates that the capacity fade of the cell stored at 60oC and 0% DOD can be attributed to the loss of active materials, and the loss of graphite anode is higher than that of composite cathode. The capacity fade of the cell stored at 60oC and 25% DOD can be caused by the lithium inventory loss, the loss of NMC, and the loss due to the morphology change of LMO. Cell stored at 50% DOD manifests similar fading behavior as that of the cell stored at 0% DOD, however, the ICA plots demonstrate that the capacity loss of the cell comes from losses of lithium inventory and NMC caused by the dissolution of transition metals with additional losses of LMO and graphite anode occur after 10 months of accumulated storage. For cell stored at 75% DOD, most the capacity loss can be due to the loss of NMC with minor contribution of lithium inventory loss, while cell stored at 100% DOD shows almost no change after storage for 12 accumulated months. These results revealed from the ICA study are consistent with those determined from the post mortem study of the electrodes obtained from cells before and after storage.

LiNi0.5Mn1.5O4 powders were prepared via a spraying-dry method followed by heating at temperatures between 600 and 1000oC for 8 hours in air with oven cooling. In order to eliminate the particle size effects, 900oC samples were annealed at 700oC under air for various durations. The crystalline structure of the prepared samples were investigated from their high resolution neutron powder diffraction data collected with Echidna at ANSTO and refined with Rietica Ver. 1.77. The results of Rietveld refinement for the NPD patterns manifest that the 700oC prepared sample contains 85% of ordered P4332 and 15% of disordered Fd m phases whereas the powders prepared at temperatures higher than 800oC prevailed with disordered Fd m phase (72`75%) with amount of rock-salt LixNi1-xO increases from 1 to 4% with heating temperature. For the annealed samples, the molar fraction of the ordered phase increases with increasing duration of annealing and converts completely into ordered phase after annealing for 60 hours. It suggests that the phase conversion and LixNi1-xO evolution/dissolution are reversible [1]. From the results of capacity retention study of the cells comprised with the prepared powders, it was found that sample prepared at 900oC with oven cooling exhibits the most promising performance among the prepared powders. These results are different from those reported by Fang et al. [2], however, they are similar to those reported previously that the disordered phase has better electrochemical properties than the ordered phase [3-5]. Though various reasons had been suggested [3, 6-7], the effects of crystalline structure on the cycling performance of high voltage spinel are still not clear. In this study, the effects are hope to reveal from the results of dissolution study for transition metals upon storage and cycling, linear sweep voltammetry for electrolyte oxidation on high voltage spinel, cyclic voltammetry for Li+ ion diffusivity, and the phase evolution detected by high resolution TEM for the fresh and cycled electrodes and in-situ NPD study. Reference: [1] L. Cai, Z. Liu, K. An, and C. Liang, J. Mater. Chem. A, 1,6908 (2013). [2] H. Fang, Z. Wang, B. Zhang, X. Li and G. Li, Electrochem. Commun., 9, 1077 (2007). [3] J. H. Kim, S. T. Myung, C. S. Yoon, S. G. Kang and Y. K. Sun, Chem. Mater., 16, 906 (2004). [4] A. Bhaskar, N. N. Bramnik, A. Senyshyn, H. Fuess and H. Ehrenberg, J. Electrochem. Soc., 157, A689 (2010). [5] K. Takahashi, M. Saitoh, M. Sano, M. Fujita and K. Kifune, J. Electrochem. Soc., 151, A173 (2004). [6] M. Kunduraci, J. F. Al-Sharab and G. G. Amatucci, Chem. Mater., 18, 3585 (2006). [7] X. H. Ma, B. Kang and G. Ceder, J. Electrochem. Soc., 157, (2010).

Cr-doped zinc gallate phosphors were prepared via citric gel route and their luminous properties were characterized by photoluminescence in this study. From the results of XRD studies, it was found that spinel phase formed exclusively in the ZnGa/sub 2-x/Cr/sub x/O/sub 4/ phosphors (O /spl les/ x /spl les/ 0.010) prepared by heat-treatment at 700/spl deg/C for 5 hours and the lattice constant increased linearly from 8.36 to 8.38 /spl Aring/ with the amount of Cr/sup 3+/-doping. The photoluminescence studies manifested that the absorbance at wavelengths of 437 and 580 nm. All of the prepared phosphors exhibit the characteristic emission peaks at wavelengths of 669, 680, 688, 694, 708, and 713 nm independent of the amount of Cr/sup 3+/-doping as they were excited with lights of wavelengths of 437 and 580 nm.

Nanosized zinc gallate phosphors were prepared via the citric gel route and their luminous properties were characterized by photoluminescence in this study. From the results of X-ray diffraction studies, it was found that a spinel phase of ZnGa 2 O 4 formed after the dry gel had been heat-treated at 470°C for 1 h and well-crystallized spinel phosphors with an average particle size of 35 nm were obtained after the dry gel had been heat-treated at 700°C for 5 h. The photoluminescence studies manifested that the shapes and the wavelengths of maximum intensity of the absorption and emission spectra were independent of the heat-treatment temperature in the range between 600 and 1000°C. Instead of the normally observed bell-shaped spectrum, peak-shaped emission spectra were observed when these nanosized phosphors were excited with UV light of wavelength of 254 nm. The peak-shaped emissions with maximum intensity at a wavelength of 470 nm correspond to the self-activated luminescence of ZnGa 2 O 4 .

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Surface modified iron nanowire nanoparticles were prepared via reduction of iron salts (FeCl3· 6H2O) under an applied magnetic field. To minimize the surface oxidation, dextran (0.05 and 0.25 wt. %) was added during the process and formed a thin passive layer over iron nanowires with alcohol and acetone used to wash iron nanowires. The complex permittivity (ɛ′-jɛ′′) and permeability (μ′-jμ″) of absorbers are measured by a cavity perturbation method from 7 to 14 GHz. In the present study, the iron nanowire prepared with 0.25 wt. % dextran and washed by acetone (D25AC) exhibited the best microwave absorption performance. Depending on the test frequency, D25AC possessed the largest permittivity loss ranged from 0.14 to 0.17 and relatively small permeability loss (

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Nanosized zinc gallate phosphors were prepared via the citric gel route and their luminous properties were characterized by photoluminescence in this study. From the results of X-ray diffraction studies, it was found that a spinel phase of formed after the dry gel had been heat-treated at 470°C for 1 h and well-crystallized spinel phosphors with an average particle size of 35 nm were obtained after the dry gel had been heat-treated at 700°C for 5 h. The photoluminescence studies manifested that the shapes and the wavelengths of maximum intensity of the absorption and emission spectra were independent of the heat-treatment temperature in the range between 600 and 1000°C. Instead of the normally observed bell-shaped spectrum, peak-shaped emission spectra were observed when these nanosized phosphors were excited with UV light of wavelength of 254 nm. The peak-shaped emissions with maximum intensity at a wavelength of 470 nm correspond to the self-activated luminescence of © 2004 The Electrochemical Society. All rights reserved.