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Abstract: A promising anode material for hybrid electric vehicles (HEVs) is Li4Ti5O12 (LTO). LTO intercalates lithium at a voltage of ∼1.5V relative to lithium metal, and thus this material has a lower energy compared to a graphite anode for a given cathode material. However, LTO has promising safety and cycle life characteristics relative to graphite anodes. Herein, we describe electrochemical and safety characterizations of LTO and graphite anodes paired with LiMn2O4 cathodes in pouch cells. The LTO anode outperformed graphite with regards to capacity retention on extended cycling, pulsing impedance, and calendar life and was found to be more stable to thermal abuse from analysis of gases generated at elevated temperatures and calorimetric data. The safety, calendar life, and pulsing performance of LTO make it an attractive alternative to graphite for high power automotive applications, in particular when paired with LiMn2O4 cathode materials. [Copyright &y& Elsevier]

Abstract: SrLi2Ti6O14 has been prepared by using mesoporous TiO2 brookite as a template and reactant. The prepared particles retained the rounded shape of the precursor, leading to high dispersivity and high packing density. The material has been further electrochemically characterized in both half and full cells. It shows good cycling stability and rate capability. A 2.7-V cell has been built by combining a SrLi2Ti6O14 anode with a 4-V spinel cathode of LiMn2O4. This cell has a higher voltage compared to the 2.5-V LiMn2O4/Li4Ti5O12 system. [Copyright &y& Elsevier]

Abstract: The hybrid pulse power characteristics (HPPC) of Li(Ni0.8Co0.15Al0.05)O2 and Li1.1(Ni1/3Co1/3Mn1/3)0.9O2 electrode materials have been evaluated according to the FreedomCAR test manual and found to meet the power requirements for HEV applications. In addition to its excellent power capability, Li1.1(Ni1/3Co1/3Mn1/3)0.9O2 electrode material has shown much better safety characteristics than the Li(Ni0.8Co0.15Al0.05)O2 electrode material. To investigate the reason for this finding, Li(Ni0.8Co0.15Al0.05)O2 and Li1.1(Ni1/3Co1/3Mn1/3)0.9O2 powders were chemically delithiated using NO2BF4 oxidizer in an acetonitrile medium. The thermal gravimetric results show that both Li0.45(Ni0.8Co0.15Al0.05)O2 and Li0.55(Ni1/3Co1/3Mn1/3)O2 obtained powders release oxygen starting from 190 and 250°C with an overall oxygen loss of 11 and 6wt% at 600°C, respectively. The reactivity of the delithiated powders with several electrolytes was studied by differential scanning calorimetry (DSC) and accelerated rate calorimetry (ARC) techniques. The relationship between the safety characteristics of Li0.45(Ni0.8Co0.15Al0.05)O2 and Li0.55(Ni1/3Co1/3Mn1/3)O2 powders and their thermal stability was discussed in light of their structural rearrangement during thermal heating. [Copyright &y& Elsevier]

LiNi0.5Co0.5O2 layered material could be a possible cathode material for advanced lithium-ion batteries in applications such as medical devices. The material was prepared by the co-precipitation method, which leads to a highly stoichiometric and homogeneous powder with a desirable particle size. It has shown reasonable cycling stability at a C/2 rate up to 100 cycles, and is expected to be much more stable at lower rates and capable of providing the needed capacity. We also showed that the use of lithium fluoroalkyl-phosphate Li[PF3(C2F5)3] salt-based electrolyte significantly improves the calendar life of the battery. Aging tests have been performed under severe conditions (storage at 50 °C and 4.1 V) clearly show a huge capacity loss for the conventional cathode LiNi0.8Co0.2O2 while LiNi0.5Co0.5O2 electrode exhibits a limited capacity fading. Finally, because it has less nickel content, differential scanning calorimetry (DSC) measurements confirm that LiNi0.5Co0.5O2 is much safe than the LiNi0.8Co0.2O2 cathode. [Copyright &y& Elsevier]

Abstract: Layered Li1.2Mn0.54Ni0.13Co0.13O2 materials were synthesized via spray pyrolysis. Synthesis conditions were varied in order to understand their effect on the electrochemical properties of the material. Three process parameters were evaluated: aerosol flow rate, reactor wall temperature and precursor concentration. Electrochemical results show excellent batch-to-batch reproducibility and no non-uniformities, as measured by energy dispersive X-ray spectroscopy (EDX). Phase purity is maintained for all the samples as measured by powder X-ray diffraction (XRD). The primary particle size has the most significant effect on the electrochemical performance of the materials with smaller primary particles promoting electrochemical activation and increasing capacity. Discharge capacities exceeding 200 mAh g−1 after 100 cycles at C/3 rate (where 1C = 200 mAh g−1) are consistently obtained over a wide range of operating conditions. Spray pyrolysis is shown to be a promising, robust synthesis technique for the production of Li1.2Mn0.54Ni0.13Co0.13O2 material, delivering excellent electrochemical performance within a wide range of process conditions. [Copyright &y& Elsevier]

Abstract: The effects of the coatings Al2O3, LiAlO x , ZrO2, TiO2, AlPO4, and LiPON and of the electrolyte additives 3-hexylthiophene and lithium difluoro (oxalato)borate (LiDFOB) on the voltage fade phenomenon in 0.5Li2MnO3·0.5LiNi0.375Mn0.375Co0.25O2 cathodes were investigated. Cells containing these materials or additives were cycled according to a standard protocol at room temperature between 2.0 and 4.7 V vs. Li+/Li. As expected, the cells containing either an additive or a coated cathode displayed less capacity loss than cells containing an uncoated cathode and no additive. The voltage fade phenomenon was quantified in terms of changes in the average cell voltage (Wh/Ah). The results indicate that, within experimental error, all of the coatings and additives produced little-to-no effect on voltage fade. [Copyright &y& Elsevier]

Abstract: Oxalic acid, tartaric acid (TA), and succinic acid (SA) are studied as chelating agents for sol–gel synthesis of Li[Li0.2Co0.13Ni0.13Mn0.54]O2 as a cathode material for lithium-ion batteries. X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy show that the materials are single-phase compounds with good crystallinities and layered α-NaFeO2 structures. The TA-material has the smallest particles (0.2–0.3 μm), with a smooth surface, and uniform distribution. Electrochemical studies indicate that the TA-material exhibits the highest initial discharge capacity (281.1 mAh g−1 at 0.1 C, 192.8 mAh g−1 at 2.0 C), the highest reversible capacity after 50 cycles (240.5 mAh g−1 at 0.1 C, 167.4 mAh g−1 at 0.5  C), and the best rate performance. The cycling stability of the SA-material is the best, with capacity retentions of 87.4% at 0.1  C and 80.1% at 0.5  C after 50 cycles. Mn4+/3+ reduction peaks appear at the first discharge process and become more evident with increasing cycle number, resulting in a spinel structure, as proved by cyclic voltammetry and differential capacity curves. Electrical impedance spectroscopy confirms that the low charge-transfer resistance of the TA-material is responsible for its superior discharge capacity and rate performance. [Copyright &y& Elsevier]

Abstract: Lithium-rich layered metal oxide Li1.1[Ni1/3Co1/3Mn1/3]0.9O2 was investigated as a potential positive electrode material for high-power batteries for hybrid electric vehicle (HEV) applications. In order to evaluate the power and life characteristics of the graphite/Li1.1[Ni1/3Co1/3Mn1/3]0.9O2 cell chemistry, hybrid pulse power characterization (HPPC) and accelerated calendar life tests were conducted on several pouch cells containing electrolytes with and without additives. The data show that the cells containing 0.5wt% lithium bis(oxalate)borate (LiBOB) or vinyl ethyl carbonate (VEC) additives, or the novel lithium difluoro(oxalato)borate (LiDFOB) additive, have much improved cycle and calendar life performance. [Copyright &y& Elsevier]