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Lithium carbonate (Li2CO3), either as a product of a conversion reaction or as an important component of the solid-electrolyte interphase (SEI) layer on the anode of a lithium ion (Li-ion) battery, is known to be chemically inactive in both reducing and oxidizing atmospheres. No sufficient evidence has shown that Li2CO3 can be reduced, let alone recognize its reduction products. Here we clarify that Li2CO3, as a product of a conversion reaction of cobalt carbonate (CoCO3) upon Li insertion, can indeed be further reduced/converted to lithium carbide (Li2C2) and lithium oxide (Li2O), based on spectroscopic and transmission electron microscopic analyses. These findings will have important guidance to designing electrode (materials) with more stable cycling performances, finding ways to convert some inert compounds into useful electrode materials, and search for electrode materials with higher specific capacities, as well as understanding the excess reversible capacity of some electrode reactions.

It is well accepted that metallic tin as a discharge (reduction) product of SnO(x) cannot be electrochemically oxidized below 3.00 V versus Li(+)/Li(0) due to the high stability of Li2O, though a similar oxidation can usually occur for a transition metal formed from the corresponding oxide. In this work, nanosized Ni2 SnO4 and NiO/SnO2 nanocomposite were synthesized by coprecipitation reactions and subsequent heat treatment. Owing to the catalytic effect of nanosized metallic nickel, metallic tin can be electrochemically oxidized to SnO2 below 3.00 V. As a result, the reversible lithium-storage capacities of the nanocomposite reach 970 mAh g(-1) or above, much higher than the theoretical capacity (ca. 750 mAh g(-1)) of SnO2, NiO, or their composites. These findings extend the well-known electrochemical conversion reaction to non-transition-metal compounds and may have important applications, for example, in constructing high-capacity electrode materials and efficient catalysts.

Perovskite lithium lanthanum titanate (LLTO) was synthesized using sol–gel method. It shows a reversible capacity of 145 mA h g−1 and moderate cycling performance between 0.01 and 2.00 V. Cyclic voltammetry and X-ray diffraction results demonstrate a two-step solid–solution reaction behavior in the voltage range of 0.00–3.00 V upon lithium insertion/extraction. A stable solid electrolyte interphase (SEI) layer is formed on the surface of LLTO after the initial discharge. Carbon coating by chemical vapor deposition improves its cycling performance significantly. Keywords: Lithium lanthanum titanate, Lithium storage mechanism, SEI formation, Carbon coating

2,4-dichlorophenol (2,4-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), and pentachlorophenol (PCP) pose a health risk to aquatic organism and humans, and are recognized as persistent priority pollutants. Selenium dependent glutathione peroxidase (Se-GPx) belongs to the family of selenoprotein, which acts mainly as an antioxidant role in the cellular defense system. In the current study, a Se-GPx full length cDNA was cloned from Anodonta woodiana and named as AwSeGPx. It had a characteristic codon at 165TGA167 that corresponds to selenocysteine(Sec) amino acid as U44. The full length cDNA consists of 870 bp, an open reading frame (ORF) of 585 bp encoded a polypeptide of 195 amino in which conserved domain (68LGFPCNQF75) and a glutathione peroxide-1 GPx active site (32GKVILVENVASLUGTT47) were observed. Additionally, the eukaryotic selenocysteine insertion sequence (SECIS) was conserved in the 3′UTR. The AwSeGPx amino acid sequence exhibited a high similarity with that of other Se-GPx. Real-time PCR analysis revealed that AwSeGPx mRNA had a widely distribution, but the highest level was observed in hepatopancreas. AwSeGPx mRNA expression was significantly up-regulated in hepatopancreas, gill and hemocytes after 2,4-DCP, 2,4,6-TCP and PCP exposure. Under similar environment, clams A. woodiana showed a more sensitive to PCP than that of 2,4-DCP and 2,4,6-TCP. These results indicate that AwSeGPx plays a protective role in eliminating oxidative stress derived from 2,4-DCP, 2,4,6-TCP and PCP treatment.

The lithium storage mechanism of carbon-coated nano-CeO2 was studied by in situ X-ray diffraction. It is found that the CeO2 stores lithium by a solid solution reaction. Due to the catalytic effect of the nano-CeO2, electrolyte decomposition occurs above 1.10 V during discharge and the solid electrolyte interphase (SEI) layer decomposes below 2.50 V during recharge. These findings help to understand the lithium storage mechanism in nano-CeO2 and demonstrate its potential applications as a room-temperature electro-catalyst. Keywords: CeO2, Lithium storage mechanism, Solid solution reaction, SEI, Catalyst

Highly ordered mesoporous crystalline MoSe2 is synthesized using mesoporous silica SBA-15 as a hard template via a nanocasting strategy. Selenium powder and phosphomolybdic acid (H3PMo12O40) are used as Se and Mo sources, respectively. The obtained products have a highly ordered hexagonal mesostructure and a rod-like particle morphology, analogous to the mother template SBA-15. The UV-vis-NIR spectrum of the material shows a strong light absorption throughout the entire visible wavelength region. The direct bandgap is estimated to be 1.37 eV. The high surface area MoSe2 mesostructure shows remarkable photocatalytic activity for the degradation of rhodamine B, a model organic dye, in aqueous solution under visible light irradiation. In addition, the synthesized mesoporous MoSe2 possess a reversible lithium storage capacity of 630 mAh g1 for at least 35 cycles without any notable decrease. The rate performance of mesoporous MoSe2 is much better than that of analogously synthesized mesoporous MoS2, making it a promising anode for the lithium ion battery.

Transition metal sulfides are regarded as another type of high-performance anode materials following the transition metal oxides for lithium ion batteries. However, the lithium storage mechanisms of these sulfides are complicated. This work is intended to evaluate the electrochemical performances of molybdenum disulfide (MoS 2 ) and find out its lithium storage mechanism at different lithium insertion stages. It is found that although the MoS 2 shows excellent cycling stability in different voltage ranges, its structural transition is irreversible in the initial cycling. In contrast to the traditional beliefs, metallic Mo is found inert and Li 2 S/S is the redox couple in a deeply discharged MoS 2 /Li cell (0.01 V vs. Li/Li + ). The metallic Mo nanoparticles are believed to be responsible for the enhanced cycling stability of the cell and act as the electronically conducting phase in the capacitive energy storage on the interfaces or grain boundaries of Mo/Li 2 S x nanocomposite. In addition, the Mo/Li 2 S nanocomposite can be used as a cathode material for lithium–sulfur batteries.

The most-popular strategy to improve the cycling stability and rate performance of the sulfur electrode in lithium-sulfur (Li-S) batteries is to astrict the sulfur in a conducting medium by using complicated chemical/physical processing. Lithium sulfide (Li(2)S) has been proposed as an alternative electrode material to sulfur. However, for its application, it must meet challenges such as high instability in air together with all of the drawbacks of a sulfur-containing electrode. Herein, we report the feasibility of using Li(2)S, which was obtained by electrochemical conversion of commercial molybdenum disulfide (MoS(2)) into Li(2)S and metallic molybdenium (Mo) at low voltages, as a high-performance active material in Li-S batteries. Metallic Mo prevented the dissolution of lithium polysulfides into the electrolyte and enhanced the conductivity of the sulfide electrode. Therefore, the in situ electrochemically prepared Li(2)S/Mo composite exhibited both high cycling stability and high sulfur utilization.

Graphene-like and platelike WS2 were obtained by solid-state reactions. High-resolution (HR) TEM, BET, and Raman scattering studies show that the graphene-like WS2 is a few-layer-structured material. It exhibits better electrochemical performances than the platelike WS2. Structural characterization indicates that metallic W and Li2S are the end products of discharge (0.01 V versus Li(+)/Li), whereas metallic W and S are the recharge (3.00 V) products. In addition, X-ray absorption near-edge structure (XANES) characterization shows that the d electrons of W deviate towards the Li (or S) atom during the discharge/charge process, thus forming a weak bond between W and Li2S (or S).

Ordered mesoporous tungsten-doped MoO(2) was synthesized by a nanocasting method. The Li storage performance of mesoporous MoO(2) is significantly improved by tungsten doping, which exhibits a reversible capacity of 700 mA h g(-1), better cycling and rate performance. This material combines the advantages of the high theoretical capacity of MoO(2) and the better electroactivity of WO(2).