Fast fluoride ion conduction of NH(4)(Mg(1-x)Li(x))F(3-x) and (NH(4))(2)(Mg(1-x)Li(x))F(4-x) assisted by molecular cations

Aiming development of the fast anion conductors, we proposed a new material design using flexible molecular cation as a host cation, and demonstrated it with fluoride ion conduction in NH(4)MgF(3) and (NH(4))(2)MgF(4) based materials. Dominant fluoride ion conduction with relatively high conductivities of 4.8 × 10(–5) S cm(−1) and 8.4 × 10(–6) S cm(−1) were achieved at 323 K in (NH(4))(2)(Mg(0.85)Li(0.15))F(3.85) and NH(4)(Mg(0.9)Li(0.1))F(2.9), respectively. It is implied that the molecular cation in the host lattice can assist the anion conduction. Our findings suggest molecular cation-containing compounds can be attractive material groups for fast anion conductors.