Preparation and performance of a novel core-shell Gel Polymer Electrolytes
A novel core-shell latex Gel Polymer Electrolytes (GPE) based on poly (methyl methacrylate-acrylonitrile -styrene) (P(MMA-AN-ST)) was prepared for applications in Li-ion batteries. The structure and the performance of the polymer and the GPE were characterized with FTIR, DSC/TG, TEM, SEM, LSV and CA. It is shown that the copolymer has a high thermal stability up to 320°C and the porous structure of the membrane was formed effectively. As-prepared gel polymer electrolytes exhibits a high ionic conductivity of 3.52×10−3 Scm−1 at 25°C and it is electrochemically stable up to 5.2V (vs. Li). This novel GPE can be potentially applied to the manufacture of PLBs.
Electrochemical characterization of poly(ethylene-co-methyl acrylate)-based gel polymer electrolytes for lithium-ion polymer batteries
Abstract Gel polymer electrolytes (GPE) composed of poly(ethylene- co -methyl acrylate) copolymer, LiBF 4 -EC/EMC/PC, and silanized fumed silica are prepared. The ionic conductivity reaches 5.8×10 −4 S cm −1 in the GPE containing 22% poly(ethylene- co -methyl acrylate), 65% LiBF 4 -EC/EMC/PC and 13% silanized fumed silica at room temperature. GPEs are free-standing films and are used to prepare thin films for rechargeable lithium-ion polymer cells. Lithium-ion polymer cells, which consist of mesophase carbon fibre anode, poly(ethylene- co -methyl acrylate)-based GPE and LiCoO 2 cathode, are assembled, and their charge–discharge cycling characteristics are investigated.
Hedy: A Gradual Language for Programming Education
One of the aspects of programming that learners often struggle with is the syntax of programming languages: remembering the right commands to use and combining those into a working program. Prior research demonstrated that students submit source code with syntax errors in 73% of cases and even the best students do so in 50% of cases. An analysis of 37 million compilations by 250.000 students found that the most common error was a syntax error, which occurred in almost 800.000 compilations. It was also found that Java and Perl are not easier to understand than a programming language with randomly generated keywords, stressing the difficulties that novices face in understanding syntax. This paper presents Hedy: a new way of teaching the syntax of a programming language to novices, inspired by educational methods by which punctuation is taught to children. Hedy starts as a simple programming language without any syntactic elements such as brackets, colons or indentation. The rules slowly and gradually change until the novices are programming in Python. Hedy is evaluated on 9714 programs.