Back Article

Figure 1. 

Schematic illustration of the configuration and operational mechanism of a typical PIB.

Figure 2. 

Different BDCMs and one of their corresponding preparation methods.

Figure 3. 

(a) Schematic diagram of the preparation process of porous activated carbon from corn husk. SEM images of (b) AC-1, (c) AC-2, (d) AC-3, and (e) AC-4. (f) The effect of the ratio of KOH and corn husk on specific surface area; cycling performance of ACs at a current density of (g) 100 mA g⁻¹ and (h) 1,000 mA g⁻¹. (i) The effect of the ratio of KOH and corn husk on the remaining capacity. Reproduced with permission^[40]. Copyright 2019, Elsevier.

Figure 4. 

(a) Schematic diagram of the catalytic synthesis of GLC from tea waste. (b) SEM. (c), (d) TEM images. (e) XRD curve. (f) Cycling performance. (g) Galvanostatic charge/discharge (GCD) curves at 100 mA g⁻¹. (h) Long-term cycling performance at 1,000 mA g⁻¹. (i) In situ XRD of GLC anode. Reproduced with permission^[47]. Copyright 2021, Royal Society of Chemistry.

Figure 5. 

(a) Synthesis process of CNC-derived CAs. (b)–(e) SEM images of CAs. (f) Structural properties. (g) Cycling performance at a current density of 0.5 C. (h) The capacity and capacity retention ratio of four anodes. (i) Separation of the capacitive and diffusion-controlled charges at 0.5 mV s⁻¹. (j) Contribution ratios of the capacitive and diffusion-controlled charge at various scan rates. Reproduced with permission^[54]. Copyright 2022, Wiley-VCH.

Figure 6. 

(a) Preparation process of rice husk-based HCs. (b), (c) SEM. (d) TEM images of HC carbonized at 1,300 °C. (e) Structural properties of HCs. (f) Pore property. (g) Cycling performance of HCs at a current density of 30 mA g⁻¹. (h) The effect of pyrolysis temperature on the capacity and ICE. (i) The contribution of the capacitance at different scan rates. (j) Diffusion coefficients of the discharge process. Reproduced with permission^[58]. Copyright 2020, Elsevier.

Figure 7. 

(a) Schematic of Fe₃C@CNT synthetic process. (b), (c) SEM images. (d), (e) TEM images. (f) CV profiles at a scan rate of 0.2 mV s⁻¹. (g) GCD curves. (h) Cycling performance in PIBs at a current density of 100 mA g⁻¹. Reproduced with permission^[66]. Copyright 2022, Elsevier.

Figure 8. 

(a)–(d) XRD curves. (e)–(h) Raman spectra. (i)–(l) SEM images of CNTs derived from Citrullus lanatus rind, Gleditsia triacanthos pod, Cocos nucifera exocarp, and Prosopis juliflora wood^[68]. Copyright 2020, Taylor & Francis.

Figure 9. 

(a) Synthetic process from soybean to CDs. (b) SEM images. (c), (d) TEM images. (e) XRD curve. (f) FT-IR. (g) Cycling performance at a current density of 100 mA g⁻¹. (h) long cycling performance at a high current density of 1,000 mA g⁻¹. (i) K⁺ storage performance kinetic analysis. Reproduced with permission^[70]. Copyright 2022, Elsevier.

Figure 10. 

(a) Synthetic process from bovine hide to Fe₂N@N-CFB. (b) XRD patterns. (c) Raman spectra. (d), (e) SEM images. (f) Rate performance. (g) Cycling performance for 100 cycles at 200 mA g⁻¹. Reproduced with permission^[76]. Copyright 2019, Springer Nature.

Figure 11. 

Main carbonization methods, their influencing factors, merits, and demerits.