Crystallinity-Engineered Hard Carbon from Upcycled Polyethylene Terephthalate for Enhanced Na Storage.

Area of Science:

• Materials Science
• Electrochemistry
• Sustainable Energy

Background:

• Developing sustainable sodium-ion battery (SIB) anodes faces challenges balancing ion transport, stability, and energy density.
• Hard carbon materials are key, but optimizing their structure for SIBs remains difficult.

Purpose of the Study:

• To address the SIB anode trilemma by engineering a hierarchical porous carbon architecture from upcycled polyethylene terephthalate (PET) waste.
• To improve sodium-ion transport, cycling stability, and energy density in SIB anodes.

Main Methods:

• Utilized ambient H2SO4/H2O2 pretreatment for crystallinity engineering and oxygen doping of PET.
• Pyrolysis to form a hierarchical porous carbon architecture (HC-OPET) with tailored porosity and expanded interlayer spacing.
• Employed DFT modeling to assess Na+ intercalation energy barriers.

Main Results:

• Developed HC-OPET with expanded pseudographitic domains (d002 = 0.41 nm) and a hierarchical porous structure.
• Achieved high reversible capacities (366 mAh g-1 at 0.1 A g-1) and excellent cycling stability (76% retention after 2000 cycles at 0.5 A g-1).
• Demonstrated synergistic benefits of mesopores for ion diffusion and micropores for Na+ storage.

Conclusions:

• The crystallinity-engineering strategy effectively converts PET waste into high-performance SIB anodes.
• The HC-OPET material offers a sustainable and scalable solution for advanced sodium-ion battery technology.
• This work presents a viable pathway for utilizing plastic waste in functional energy materials.