Porous glass-ceramics cation exchangers: Cation exchange properties of porous glass-ceramics with skeleton of fast Li ion-conducting LiTi₂(PO₄)₃ crystal

Abstract

Lithium titanium orthophosphate LiTi2(PO4)3 (LTP) has attracted attention as a chemically stable fast Li+-conductor in ambient atmosphere. It was reported in our previous paper7 that monolithic microporous glass-ceramics with a skeleton of this crystal were successfully prepared from glasses in the pseudobinary system of LTP and Ca3(PO4)2. Here we report that these porous glass-ceramics (mean pore diameter: ∼40 nm; total specific surface area: ∼30 m2; porosity: ∼45 vol.%) show excellent cation exchange properties. Approximately 50% of Li+ ions in the materials are exchanged with monovalent ions with ionic radii smaller than 130 ppm in 1 h at room temperature. In particular, Li+ ions are selectively exchanged with Ag+ ions even in the presence of Na+ ions. The exchange rate in the porous glass-ceramics is larger by two orders of magnitude than that of sintered LTP. The ratio of these exchange rates is close to that of the total surface areas, indicating that most of the pores in porous LTP glass-ceramics are available for ion exchange reactions. These are the first porous glass-ceramics having excellent cation exchange properties.

Preparation, microstructure and electrical properties of Li1.4Al0.4Ti1.6(PO4)3 nanoceramics

“…Glass-ceramics is a category of materials of great potential as solid electrolytes because they can be made into desired shape and size easily, have favorable microstructure and exhibit good chemical stability. A few literatures have reported the improvement in electrical properties of NASICON-typed solid lithium ion conductors compared with their conventional ceramic analogues [5][6][7][8][9].…”

Lithium ion conductive glass ceramics in the system Li1.4Al0.4(Ge1?xTix)1.6(PO4)3 (x=0?1.0)

“…The lithium analogues of NZP, Li 1 + x M 2 À x MV x P 3 O 12 where Zr is replaced by M = Ti, Ge or Hf and MV= Al or In have been found to exhibit excellent lithium ion conductivity in the range of 2 -8 Â 10 À 4 S/cm at room temperature [2][3][4][5][6][7]. However, grain boundary effects and difficulties in obtaining dense ceramic products to great extent restricted their practical use as solid electrolytes.…”

Influence of Fe 2 O 3 on non-isothermal crystallization kinetics and microstructure of lithium titanium phosphate glass-ceramics

“…He has identified the restricted glass-forming regions of this system [14]. Glass-ceramics belonging to the Li 2 OTiO 2 -P 2 O 5 system exhibit superior properties such as ionic conductivity [2] and ion-exchange capacity [15] due to the formation of an alkali or alkaline-earth titanium phosphate phase which is called NASICON [4,[15][16][17]. NASICON crystals with the formula of LiTi 2 (PO 4 ) 3 , built up by corner-sharing of TiO 6 octahedron and PO 4 tetrahedron, form a class of super ionic conductors [4,[18][19][20].…”