Solid-state NMR For ¹⁵N-¹⁵N Correlations And PEO/Urea/Alkali-salts Ternary Solid Polymer Electrolytes

In the first part, we have done the researches on probing ¹⁵N-¹⁵N space correlations in the ¹⁵N-labelled g-C3N4 samples by solid-state NMR. PDSD （Proton-Driven Spin-Diffusion） and SHA+（Second-order Hamiltonian among Analogous nuclei plus） sequences are compared in this experiment. We find that SHA+ sequence is much more efficient to probe ¹⁵N-¹⁵N space correlations than PDSD. It was also found that polarization transfer between ¹⁵N atoms for PDSD and SHA+is only efficient when one of the nitrogen atoms bonds to protons. Therefore SHA+ should be valuable for the nitrogen-doped carbon materials.In the second part, a new kind of ternary complex solid polymer electrolyte, which is based on the PEO-urea inclusion compound, is introduced here. The PEO-urea-LiTFSI solid polymer electrolyte not only has the same crystalline structure with a-PEO-urea, but also shows the property of high ionic conductivity. Our study may motivate further researches on the ternary complex solid polymer electrolytes with high ionic conductivity.