In this paper, we are proposing a new algorithm that improves the performance of the DBSCAN clustering algorithm using a packed X-tree. The proposed algorithm does not require the minpoints and eps values. We have extensively described how the system is achieved and we have also proposed a new effective method for finding the knearest neighbours of spatial objects in a large database. The study shows that the proposed method is very efficient and will greatly accelerate the operations of density based clustering in large dataset as against the existing methods.
Many efforts are being made to tune perovskite thin film cathodes toward improving their oxygen reduction kinetics and thereby improving overall solid oxide fuel cell performance. One approach is to enhance oxygen diffusion via introduction of larger concentrations of grain boundaries during thin film growth. While such grain boundary engineering has been shown to enhance ionic transport and surface reaction kinetics in some cases, little attention has been paid on its corresponding influence on electronic conductivity. To provide insights into the role of grain boundaries and their contribution to the cathode performance, we have investigated separately the electronic and ionic conductivity of La 0.8 Sr 0.2 MnO 3 (LSM) thin films by Van-der-Pauw and 18 O tracer exchange measurements respectively, as well as their combined contributions by electrochemical impedance spectroscopy. All three types of experiments were performed on the same kind of samples with varying LSM microstructure to illustrate the effects of grain boundaries on both electron and ion conduction. Correlations between active electrode area and microstructure-dependent partial conductivities are presented. The findings can also be used for optimizing current collector spacing in thin film solid oxide fuel cells.©The
Solid state electrolyte systems boasting Li+ conductivity of >10 mS cm−1 at room temperature have opened the potential for developing a solid state battery with power and energy densities that are competitive with conventional liquid electrolyte systems. The primary focus of this review is twofold. First, differences in Li penetration resistance in solid state systems are discussed, and kinetic limitations of the solid state interface are highlighted. Second, technological challenges associated with processing such systems in relevant form factors are elucidated, and architectures needed for cell level devices in the context of product development are reviewed. Specific research vectors that provide high value to advancing solid state batteries are outlined and discussed.
Mechanical and electrochemical phenomena are coupled in defining the battery reliability, particularly for solid-state batteries. Micro-cracks act as barriers to Li-ion diffusion in the electrolyte, increasing the average electrode's tortuosity. In our previous work, we showed that solid electrolytes are likely to suffer from mechanical degradation if their fracture energy is lower than 4 J m(-2) [G. Bucci, T. Swamy, Y.-M. Chiang, and W. C. Carter, J. Mater. Chem. A (2017)]. Here we study the effect of electrolyte micro-cracking on the effective conductivity of composite electrodes. Via random analyzes, we predict the average diffusivity of lithium in a solid-state electrode to decrease linearly with the extension of mechanical degradation. Furthermore, the statistical distribution of first passage times indicates that the microstructure becomes more and more heterogeneous as damage progresses. In addition to power and capacity loss, a non-uniform increase of the electrode tortuosity can lead to heterogeneous lithiation and further stress localization. The understanding of these phenomena at the mesoscale is essential to the implementation of safe high-energy solid-state batteries. (C) The Author(s) 2017. Published by ECS. All rights reserved.
