Conduction below 100 ^°C in nominal Li₆ZnNb₄O₁₄

The increasing demand for a safe rechargeable battery with a high energy density per cell is driving a search for a novel solid electrolyte with a high Li⁺ or Na⁺ conductivity that is chemically stable in a working Li-ion or Na-ion battery. Li₆ZnNb₄O₁₄ (LZNO) has been reported to exhibit a σ _Li > 10⁻² S cm⁻¹ at 250 °C, but to disproportionate into multiple phases on cooling from 850 °C to room-temperature. An investigation of the room-temperature Li-ion conductivity in a porous pellet of a multiphase product of a nominal LZNO composition is shown to have bulk σ _Li ≈ 3.3 × 10⁻⁵ S cm⁻¹ at room-temperature that increases to 1.4 × 10⁻⁴ S cm⁻¹ by 50 °C. ⁷Li MAS NMR spectra were fitted to two Lorentzian lines, one of which showed a dramatic increase with increasing temperature. A test for water stability indicates that Li⁺ may move to the particle and grain surfaces to react with adsorbed water as occurs in the garnet Li⁺ conductors.