Ao Mei

Polymer composite electrolytes containing ionically active mesoporous SiO2 particles

In exploring approaches to enhance ionic conductivity of solid polymer electrolytes, adding inert fillers has proved to be effective. In the present work, by doping ionically active SiO2 particles, which were designed by absorbing and confining liquid plasticizers in the nanosized pores of SBA-15 (a kind of mesoporous SiO2) to the polyethylene oxide (PEO)-LiClO4 matrix, about 10-fold further enhancement in the ionic conductivity was achieved as compared with adding inert SBA-15. The fillers dispersed homogenously in the PEO matrix. The ambient ionic conductivity reaches about 1.5×10−4 S cm−1 for (PEO)8-LiClO4∕10 wt % active SBA-15 films. Moreover, other properties such as the ambient lithium transference number, long-term stability of bulk and lithium metal electrode/electrolyte interfacial resistance, and the electrochemical window also showed good results. Application of such electrolytes in lithium batteries was asserted by cell testing with LiCoO2 cathode and lithium metal anode.

Effects of grain modification on the dielectric properties of A0.03Ti0.10Ni0.87O (A:K+,Mg2+,Y3+) ceramics

We prepared K+-, Mg2+-, and Y3+-doped Ni–Ti–O polycrystalline ceramics by chemical synthesis combined with a traditional ceramic processing. Analysis of the microstructure and phase composition reveals that a core/shell structure can be observed and NiTiO3 phase exists as the grain boundary. Our results indicate that K+, Mg2+, and Y3+ doping have remarkable influence on the dielectric properties of these NiO-based ceramics, which should be mainly attributed to the large variation of the activation energies of the conductivity in the grain interiors. The special core/shell structure and related interfacial polarization are responsible for the observed high dielectric behavior.

Formation Mechanism of Garnet-Like Li7La3Zr2O12 Powder Prepared by Solid State Reaction

Abstract The formation mechanism of garnet-like Li 7 La 3 Zr 2 O 12 (LLZO) phase was investigated using LiOH·H 2 O as raw materials by XRD and DTA/TG measurements. It is found that the reaction mechanism of the LLZO formation is as follows: 7Li 2 O+3La 2 O 3 +4ZrO 2 =2Li 7 La 3 Zr 2 O 12 . The LLZO phase forms at about 680 °C according to the XRD patterns, which is in agreement with the thermic peak at 700 °C in DTA/TG curves, and the peak arises from the formation of LLZO phase. The temperature range of stable LLZO phase is wider, from 720 to 1000 °C. However, LLZO is thermally unstable at the high temperatures ( 2 Zr 2 O 7 . And the amount of the decomposed products increases, and LLZO decreases gradually with the increase of the calcination temperature. When the reactant mixture is calcined at low temperature, the produced phases are identified to be lanthanum compounds because La 2 O 3 absorbs moisture and CO 2 very easily. The chemical reactions at lower temperature are mainly related with the reactions among lanthanum compounds. LLZO powder could be synthesized by solid state reaction at 800 °C. It is found that the LLZO crystal belongs to the tetragonal symmetry. SEM observation shows that the obtained LLZO powder is nano-sized.

Synthesis and Thermoelectric Properties of Ca2Co2O5 Ceramics

The precursor of Ca2Co2O5 was prepared by coprecipitation method. The bulk Ca2Co2O5 samples were prepared by conventional sintering and Spark Plasma Sintering (SPS), respectively. The relative density of bulk Ca2Co2O5 ceramic, which was prepared by conventional sintering is about 75%; while the samples prepared by SPS has a density of 98%. The thermoelectric properties were enhanced by SPS, compared with samples prepared with conventional sintering. The maximum powerfactor of the conventional sintering and SPS samples are 2.70×10-4W∙m-1∙K-2 and 3.85×10-4 W∙m-1∙K-2, respectively.

High Temperature Thermoelectric Properties of Oxide Ca2Co2O5

Ca2Co2O5 ceramic powders were synthesized by the coprecipitation method and consolidated by spark plasma sintering (SPS) technique.The observation by the SEM indicated that the ceramics body showed fine and layer microstructure.The density of the body increased with an increase of the fritting temperature.XRD patterns showed that the ceramics sample exhibits inpure phase with increasing the sintering temperayure to 850°C and that the grain was preferentially oriented.The electrical conductivity was reduce and the Seebeck coefficient slightly increased with an increase of the sintering temperature.As a result,the thermoelectric properties of the sample prepared by SPS at 800 °C for 5 min was better than the sample prepared by SPS at 750 °C for 5 min at high temperature.The sample treated by the SPS process under the condition of 800 °C,40 MPa and 5 min showed the maximum power factor (PF) of 3.85×10-4W∙m-1∙K-2 at 923 K.