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Liang et al. Energy Mater 2023;3:300006 https://dx.doi.org/10.20517/energymater.2022.63 Page 5 of 14

Figure 1. Schematic diagram of the synthesis and functional structure of the CZGNF separator.

Figure 2. (A) FTIR spectrum of GNF; (B) XRD patterns of ZIF-67, GNF, and CZGNF.

Figure 3 displays the microstructure and fiber diameter distribution of the PP separator, GNF separator, and
CZGNF separator. The surface of the PP separator presents irregular large pores with a width of about 600
nm-1 μm [Figure 3A]. These large pores can pass not only lithium ions but also macromolecular lithium
polysulfides, thus causing a serious “shuttle effect”. The GNF separator and CZGNF separator prepared by
electrospinning exhibited the phenomenon of random intertwining of the, thus forming a three-
dimensional (3D) fiber network structure [Figure 3B and C]. This fibrous mesh structure can effectively trap
lithium polysulfide and prevent its diffusion to the lithium anode. After the addition of C and ZIF-67
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particles, the separator facing cathode surface appeared light purple [Figure 3C]. The successful doping of
C can be further proved by XRD pattern. In addition, there is no washing, pickling, etc. in the dissolution
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process. After the dissolution process, the solution is sprayed directly by electrospinning, so C and ZIF-67
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were in the film certainly. Moreover, the color of ZIF-67 is purple, and the color of the prepared film facing
the cathode is also light purple. Therefore, it can be determined that C and ZIF-67 have been successfully
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added. The CZGNF separator is white on one side and gray-purple on the other due to different spinning
solutions. The thickness of the CZGNF separator is about 72 μm [Figure 3D]. The main reason for the
different morphology of GNF and CZGNF is the addition of C and ZIF-67, which leads to the increased
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electrical conductivity of the co-spun polymer nanofibers. Moreover, when the nanofibers are prepared by