fig7

Figure 7. Nyquist plots of PBF@N@S-S-50%, PBF@N-S-50%, and PBF-S-50% cathodes (A) and Nyquist plots of PBF@N@S-S-50% after 1st, 10th, 20th, 50th, 100th, and 200th cycles (B). PBF: Bare biochar fibers; PBF@N: N-doped porous biochar fibers; PBF@N@S: N, S dual-doped porous biochar fibers.