High temperature X-ray diffraction study of the formation of Na_(2)Ti_(3)O_(7) from a mixture of sodium carbonate and titanium oxide  

作　　者：Caroline Piffet Bénédicte Vertruyen Frédéric Hatert Rudi Cloots Frédéric Boschini Abdelfattah Mahmoud 

机构地区：[1]GREENMAT,CESAM Research Unit,Chemistry Department,University of Liège,4000 Liège,Belgium [2]Laboratory of Mineralogy,Geology Research Unit,University of Liège,4000 Liège,Belgium

出　　处：《Journal of Energy Chemistry》2022年第2期210-218,共9页能源化学（英文版）

基　　金：supported by the Walloon Region under the “PE PlanMarshall2.vert”program(BATWAL–1318146)。

摘　　要：Na2Ti3O7 has attracted much attention in the field of anode materials for Na-ion batteries thanks to its non-toxicity and very low working potential of 0.3 V vs Na0/Na+.Building a clearer picture of its formation from cheap Na_(2)CO_(3) and TiO_(2) starting materials is therefore of obvious interest.Here,we report new insights from an in-situ high temperature X-ray diffraction study conducted from room temperature to 800°C,complemented by ex-situ characterizations.We were thereby able to position the previously reported Na_(4)Ti_(5)O_(12) and Na_(2)Ti_(6)O_(13) intermediate phases in a reaction scheme involving three successive steps and temperature ranges.Shifts and/or broadening of a subset of the Na_(2)Ti_(6)O_(13) reflections suggested a combination of intra-layer disorder with the well-established ordering of successive layers.This in-situ study was carried out on reproducible mixtures of Na_(2)CO_(3) and TiO_(2) in 1:3 molar ratio prepared by spraydrying of mixed aqueous suspensions.Single-phase Na_(2)Ti_(3)O_(7) was obtained after only 8 h at 800°C in air,instead of a minimum of 20 h for a conventional solid-state route using the same precursors.Microstructure analysis revealed~15 mm diameter granules made up from rectangular rods of a fewmm length presenting electrochemical properties in line with expectations.In the absence of grinding or formation of intimate composites with conductive carbon,the specific capacity of 137 m Ah/g at C/5 decreased at higher rates.

关 键 词：Formation mechanism High temperature XRD Na_(2)Ti_(3)O_(7) Spray-drying synthesis Na-ion batteries 

分 类 号：TQ131.12[化学工程—无机化工] TM912[电气工程—电力电子与电力传动]