Transport and structural properties of (CH ₃ ) ₄ NBF ₄ with nanodiamonds filler

Composite solid electrolytes are promising materials for electrochemical devices. The most interesting ionic components for them are salts of substituted ammonium due to their high thermal and electrochemical stability, but the properties of composites based on them are poorly understood. Composite solid electrolytes based on the substituted ammonium salt (CH3)4NBF4 with highly dispersed nanodiamonds CND with specific surface area Ssp = 300±20 m2/g in a wide range of filler concentrations have been synthesized for the first time. It was found by X-ray diffraction method that the introduction of СND leads to the amorphization of the salt. The highest conductivity values are characterized by the composite 0.03(СH3)4NBF4 – 0.97CND (σ = 4.2∙10–3 S/cm at 300 °C), whose electrical conductivity is 3-4 orders of magnitude higher than that of the original salt. Modeling the concentration dependence of the electrical conductivity of the composites using the mixing equation showed that the reason for the increase in electrical conductivity is the formation of an amorphous salt layer, the electrical conductivity of which is 4–5 orders of magnitude higher than that of the crystalline phase (CH3)4NBF4.