The Study Of Silicate Lithium Fast Ion Conductors

Fast ion conductor, which is of great influence on lithium ion batteries, becomes the hotspot of academe now. Due to the great diversity of silicate, the study of silicate solid electrolyte is one of the most interesting systems of lithium solid electrolyte. This dissertation is focused on the silicate lithium fast ion conductor with difference oxide included. The first part is about some backgrounds for this dissertation. The recent situation and advance in the studies on the lithium fast ion conductors and its theories and study methods are reviewed. The second part and the third part discussed the fast ion conductors of different silicate system, which included different number of oxide. The mixture uniform design is introduced into the study of multicomponent silicate fast ion conductors. The study area is extending to the whole compounding recipe space. In order to ensure the impartiality of the experiment data, the traditional high temperature solid synthesis and sinter method are used to prepare the sample. The results showed that the high efficiency of the uniform design experiment method. Plenty of information is getting by the numbered experiment. The U10(10²) uniform design table was used to study the three members system: Li₂O-Re₂O₃-SiO₂(Re=La,Y,Nd) system ,and Li₂O-V₂O₅-SiO₂ system;the U7(7²) uniform design table was used in Li₂O-MO-SiO₂(M=Mg,Zn) system. Among these systems the Li₂O-V₂O₅-SiO₂ system showed that the ionic conductivity and electronic conductivity. With increasing of SiO₂ the electronic conductivity is decreased. The preferable lithium fast ion conductor of such system is received which ambient conductivity reached up to 1.5×10^-4S/cm, and the electronic conductivity is 4 order of magnitude less than the ion conductivity. The uniform design table U12(12³) is used for the four members system. Based on the study of three members system LSV, the four members system is introduced and the trivalent oxide Al2O3,the tetravalent oxide SnO2,and the pentavalent oxide P2O5 were introduced into the four members system respectively to obtain the three system fast ion conductors of LASV,LSVSn,LSVP. Because of the V2O5,some of component of these systems have the electronic conductivity. When the insulated oxide is appended some of component in these systems, they became the fine fast ion conductors. The results indicated that the conductivity reached up to 10-4S/cm at ambient temperature. And the other four members systems LASP and LATP, which have the different tetravalent oxide, have been researched. The results showed that the cation field intensity and its coordinate number decide the component of better fast ion conductor. And this result is also available for the all oxide systems. In this dissertation several multivariate multinomial model are used in regression analysis to obtain the component-conductivity formulation, and the factor that the conductivity concerned. And the compound number which could exist in three or four members silicate was researched in this dissertation.