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Mixed Phase Solid‐State Plastic Crystal Electrolytes Based on a Phosphonium Cation for Sodium Devices
Author(s) -
Makhlooghiazad Faezeh,
Gunzelmann Daniel,
Hilder Matthias,
MacFarlane Douglas R.,
Armand Michel,
Howlett Patrick C.,
Forsyth Maria
Publication year - 2017
Publication title -
advanced energy materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.08
H-Index - 220
eISSN - 1614-6840
pISSN - 1614-6832
DOI - 10.1002/aenm.201601272
Subject(s) - plastic crystal , materials science , electrolyte , ionic conductivity , electrochemistry , phase (matter) , lithium (medication) , phosphonium , sodium , fast ion conductor , conductivity , crystal (programming language) , inorganic chemistry , chemical engineering , electrode , chemistry , polymer chemistry , organic chemistry , metallurgy , medicine , endocrinology , engineering , computer science , programming language
Na batteries are seen as a feasible alternative technology to lithium ion batteries due to the greater abundance of sodium and potentially similar electrochemical behavior. In this work, mixed phase electrolyte materials based on solid‐state compositions of a tri methylisobutylphosphonium (P 111i4 ) bis( tri fluromethanesulphonyl)amide (NTf 2 ) organic ionic plastic crystal (OIPC) and high concentration of NaNTf 2 that support safe, sodium metal electrochemistry are demonstrated. A Na symmetric cell can be cycled efficiently, even in the solid state (at 50 °C and 60 °C), for a 25 mol% (P 111i4 NTf 2 )–75 mol% NaNTf 2 composition at 0.1 mA cm −2 for 100 cycles. Thus, these mixed phase materials can be potentially used in Na‐based devices under moderate temperature conditions. It is also investigated that the phase behavior, conductivity, and electrochemical properties of mixtures of NaNTf 2 with this OIPC. It is observed that these mixtures have complex phase behavior. For high compositions of the Na salt, the materials are solid at room temperature and retain a soft solid consistency even at 50 °C with remarkably high conductivity, approaching that of the pure ionic liquid at 50 °C, i.e., 10 −3 –10 −2 S cm −1 .