Post-anneal effect on the structural and Li + conduction properties in NaI - LiBH 4 system
- PDF / 317,444 Bytes
- 6 Pages / 432 x 648 pts Page_size
- 86 Downloads / 214 Views
Post-anneal effect on the structural and Li+ conduction properties in NaI - LiBH4 system Reona Miyazaki1, Dai Kurihara1, Daiki Hayashi1, Seiya Furughori1, Masatoshi Shomura1 and Takehiko Hihara1 1 Physical Science and Engineering, Graduate School of Engineering, Nagoya Institute of Technology, Nagoya 466-8555, Japan ABSTRACT In the present work, NaI – LiBH4 system fabricated by ball milling were post annealed and their variation of Li+ ion conductivity were investigated. From the change of lattice parameters by post annealing, it was suggested that unreacted LiBH4 existed in as-milled sample further dissolved into NaI, which implied an enhancement of the sample homogeneity. On the other hand, the segregation of LiI was anticipated when ball milled 15NaI·LiI (BH4 free sample) was annealed at 423 K. Li+ conductivity was decreased by post anneal process and compositional dependence of an activation energy for Li+ conduction was indicated for the homogeneous NaI – LiBH4 system. INTRODUCTION Lithium ion batteries (LIBs) are widely used as a power supply of various kinds of portable devises around us, such as laptop PC and smart phone etc. because of their high energy density. However, since their organic liquid electrolytes are highly flammable, the conventional LIBs inevitably contain the risk of ignition. For example, the smoking accident of the smart phone in an aircraft is still fresh in our memory. Although the size of LIBs are small as long as they are used in mobile devices, their application for the power supply of electric vehicles will make it extremely risky due to the enlargement of battery size. The use of solid electrolytes, where Li+ ion can migrate easily in their lattices, are the promising alternative. Because most of the high Li+ ion conductive materials are ceramics including oxides[1-3], sulphides[4,5] and mixed halides[6,7] etc., they are basically nonflammable compounds. LIBs, where solid electrolytes are used instead of the conventional organic electrolyte are called as all-solid-state batteries and they have attracted much attention as a future generation battery. Generally, liquid electrolytes are fabricated by dissolving Li salts into water and/or a given organic liquid. However, from the early stage of the research, most of the solid electrolytes have been developed based on Li salts themselves. Our group has been synthesized pure Li+ ionic conductors via doping of Li salt into KI and NaI (or solid solvent), which is just in a similar way as the fabrication of liquid electrolytes[8,9]. In our previous work, NaI doped with 6 mol% of LiBH4 has been fabricated by ball milling. Although NaI was confirmed to become a pure Li+ conductor via doping of small amount of LiBH4, a certain amount of non-uniformity in the concentration of Li was indicated. In this work, the effect of post annealing on the Li+ ion conduction properties of NaI – LiBH4 systems are investigated.
389 Downloaded from https:/www.cambridge.org/core. Cornell University Library, on 11 May 2017 at 07:01:43, subject to the Cambridge C
Data Loading...
