Selective Oxidation of CO in Excess H_2 over Ru/Al_2O_3 Catalysts Modified with Metal Oxide

The Ru/Al2O3 catalysts modified with metal oxide （K20 and La2O3） were prepared v/a incipient wetness impregnation method from RuCl3.nH2O mixed with nitrate loading on Al2O3 support. The activity of catalysts was evaluated under simulative conditions for the preferential oxidation of CO （CO-PROX） from the hydrogen-rich gas streams produced by reforming gas, and the performances of catalysts were investigated by XRD and TPR. The results showed that the activity temperature of the modified catalysts Ru-K20/Al2O3 and Ru-La2O3/Al2O3 were lowered approximately 30℃ compared with pure Ru/Al2O3, and the activity temperature range was widened. The conversion of CO on Ru-K20/Al2O3 and Ru-La2O3/Al2O3 was above 99% at 140-160℃, suitable to remove CO in a hydrogen-rich gas and the selectivity of Ru-La2O3/Al2O3 was higher than that of Ru-K2O/Al2O3in the active temperature range. Slight methanation reaction was detected at 220℃ and above.

Enhanced electrochemical performance of garnet-based solid-state lithium metal battery with modified anodic and cathodic interfaces

Due to high ionic conductivity and wide electrochemical window,the garnet solid electrolyte is considered as the most promising candidate electrolyte for solid-state lithium metal batteries.However,the high contact impedance between metallic lithium and the garnet solid electrolyte surface seriously hampers its further application.In this work,a Li-(ZnO)_(x)anode is prepared by the reaction of zinc oxide with metallic lithium and in situ coated on the surface of Li_(6.8)La_(3)Zr_(1.8)Ta_(0.2)O_(12)(LLZTO).The anode can be perfectly bound to the surface of LLZTO solid electrolyte,and the anode/electrolyte interfacial resistance was reduced from 2319 to 33.75Ω·cm^(2).The Li-(ZnO)_(0.15)|LLZTO|Li-(ZnO)_(0.15) symmetric battery exhibits a stable Li striping/plating process during charge-discharging at a constant current density of0.1 m A·cm;for 100 h at room temperature.Moreover,a Li-(ZnO)_(0.15)|LLZTO-SPE|LFP full battery,comprised of a polyethylene oxide-based solid polymer electrolyte(SPE)film as an interlayer between LiFePO4(LFP)cathode and LLZTO solid electrolyte,presents an excellent performance at 60℃.The discharge capacity of the full battery reaches 140 mA·h·g^(-1)at 0.1 C and the capacity attenuation is less than3%after 50 cycles.

Controllable Morphology Tailoring with Solvothermal Method Toward LiMnPO_(4)/C Cathode Materials for Improved Performance and Favorable Thermostability

An environmentally friendly method for the synthesis of LiMnPO_(4)/C anode material for lithium-ion batteries by solvothermal method is introduced.The modification of the morphology of this precursor is altered by changing the ratio of the conditioning solvent(water-ethylene glycol solution)and the order of material addition.Ethylene glycol(EG)exerts a considerable influence on synthesizing LiMnPO_(4)/C flake-like nanocrystal,which benefits the extraction/insertion reaction of lithium ions and improves the electrochemical activity and electrochemical performance of LiMnPO_(4)/C material.When the solvent composition is H_(2)O:EG=1:3,exhibiting exceptional charge/discharge performance and rate capability,the specific discharge capacities are 155.8,153.7,148.8,141.4,129.5,and 112.6 mAh g^(−1) at the 0.1,0.2,0.5,1,2,and 5 C rates,respectively.When the charge-discharge rate returns to 0.1 C,the LiMnPO_(4)/C material shows a reversible discharge specific capacity of 153.7 mAh g^(−1).Differential scanning calorimetry(DSC)tests verify that the thermodynamic stability of the prepared LiMnPO_(4)/C(LMP)and commercial LiFePO_(4)(LFP)materials is better than that of commercial nickel-cobalt-aluminum(NCA)ternary materials.These prepared LiMnPO_(4)/C composites have high electrochemical capacity and cycle stability.

Synthesis of Hollow Three-Dimensional Channels LiNi_(0.5)Mn_(1.5)O_4 Microsphere by PEO Soft Template Assisted with Solvothermal Method

A appropriate size with three-dimension(3 D) channels for lithium diffusion plays an important role in constructing highperforming LiNi_(0.5)Mn_(1.5)O_4(LNMO) cathode materials, as it can not only reduce the transport path of lithium ions and electrons, but also reduce the side effects and withstand the structural strain in the process of repetitive Li~+ intercalation/deintercalation. In this work, an e fficient method for designing the hollow LNMO microsphere with 3 D channels structure by using polyethylene oxide(PEO) as soft template agent assisted solvothermal method is proposed. Experimental results indicate that PEO can make the reagents mingle evenly and nucleate slowly in the solvothermal process, thus obtaining a homogeneous distribution of carbonate precursors. In the final LNMO products, the hollow 3 D channels structure obtained by the decomposition of PEO and carbonate precursor in the calcination can provide abundant electroactive zones and electron/ion transport paths during the charge/discharge process, which benefits to improve the cycling performance and rate capability. The LNMO prepared by adding 1 g PEO possesses the most outstanding electrochemical performance, which presented an excellent discharge capacity of 143.1 mAh g~(-1) at 0.1 C and with a capacity retention of 92.2% after 100 cycles at 1 C. The superior performance attributed to the 3 D channels structure of hollow microspheres, which provide uninterrupted conductive systems and therefore achieve the stable transfer for electron/ion.

Effect of Different Calcination Temperatures on the Structure and Properties of Zirconium-Based Coating Layer Modified Cathode Material Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)

Lithium-rich manganese-based oxides have the advantages of high discharge specific capacity, so they are potential candidates for advanced lithium battery cathode materials. However, they also have drawbacks to be solved such as serious irreversible loss of capacity and voltage decay in the cycling process. Surface coating method was used in this paper to modify the lithium-rich manganese-based oxide(LRMO,Li_(1.2)Mn_(0.54)Ni_(0.13)Co_(0.13)O_(2)) to improve its electrochemical properties. Zirconium-based compounds coated LRMO materials(ZBC@LRMO) were obtained via the reaction of lithium hydroxide with zirconium n-butanol and subsequent thermal treatment at different temperatures. The results of X-ray diffraction and transmission electron microscopy confirm that the crystal structure and composition of the ZBC coating layer vary with the calcination temperature. The coating layer obtained at 600 ℃ is composed of tetragonal ZrO_(2) and Li_(2)ZrO_(3). The ZBC@LRMO sample with tetragonal ZrO =2 and Li_(2)ZrO_(3) composite exhibits the best electrochemical performance: the discharge capacity of ZBC@LRMO can reach 296 mAh g^(-1) at 0.1 C and 120 mAh g^(-1) at high rate of 5 C.