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Figure 2. (A) SEM image and cycling stability of PBPC-1000^[59]. Copyright 2018, Elsevier; (B) SEM image and cycling stability of NOBC-2^[60]. Copyright 2021, Elsevier; (C) SEM image and cycling stability of DS^[61]. Copyright 2020, Elsevier; (D) SEM image and cycling stability of H-OS-C^[62]. Copyright 2019, Elsevier; (E) SEM image and cycling stability of NHPC^[63]. Copyright 2019, Elsevier. NOBC: N/O co-doped cage-type biomass carbon; DS: dandelion seeds; H-OS-C: hydrolytic cotton-derived oxygen/sulfur co-doped carbon; SEM: scanning electron microscope; PBPC: potato biomass porous carbon.