3D cross-linking N-doped graphene framework for high sulfur nanocrystal storage

Three-dimensional (3D) nitrogen-doped graphene frameworks contributing to high-efficiency and high-stability Li-S batteries have received wide interest in energy storage fields. Herein, a 3D nitrogen-doped graphene composite framework was prepared with spatial dendritic triamines as crosslinking interconnectors, and subsequently employed for Li-S batteries with high efficiency and stability. The nanoscale spatial network of triamine-bonded graphene as molecular spacers can enlarge the interlayer spacing and change surface topography, which allows the nanocomposites to inhibit phase separation and thus capture and homogeneously store well-dispersed sulfur nanocrystals at a high capacity exceeding 70%, even by a solution process. In our work, the composite of S@GO-TAPA as the cathode material delivers the highest initial discharge capacity of 965 mAh g⁻¹. Besides that, an average coulombic efficiency of 91% is achieved after more than 100 cycles and 66.5% of the capacity remains, even after 100 cycles at 0.2 °C. The results suggest that the shuttle effect is remarkably suppressed. Therefore, the design strategy for cathode media is promising for fully solution-processing energy storage devices with printing, coating and spraying techniques. (paper)