fig15

Figure 15. (A) HAP sub-nanofiber structure; (B) PEI-HAP composite with ultra-low filler content, showing chain distribution/mobility in matrix (dense) and interface (loose); (C) U_d and η of PEI, PEI-0.5wt.%HAP, and PEI-0.5wt.%SF at 200 °C vs. electric field; (D) U_e vs. discharge time for PEI-0.5wt.%HAP (200 °C) and BOPP (70 °C)^[118]. HAP: Hydroxyapatite; PEI: polyetherimide; U_d: discharge energy density; η: charge/discharge efficiency; U_e: energy storage density.