Engineering carbon nanosheets with hexagonal ordered conical macropores as high-performance sodium-ion battery anodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Hard carbons are promising sodium-ion battery anodes but face challenges with rate performance due to slow ion transfer and kinetics.
• Optimizing the structure of carbon materials is crucial for improving their electrochemical behavior in sodium-ion batteries.

Purpose of the Study:

• To develop novel carbon nanosheets (CNS) with ordered conical macropores for enhanced sodium-ion battery anode performance.
• To investigate the relationship between the carbon microcrystal structure, interlayer spacing, and sodium storage behavior.
• To achieve superior rate capability and cycling stability in sodium-ion battery anodes.

Main Methods:

• Preparation of carbon nanosheets (CNS) with hexagonal ordered conical macropores.
• Tailoring carbon microcrystal structure and interlayer spacing by adjusting carbonization temperature.
• Electrochemical characterization including capacity, rate capability, and cycling stability tests.

Main Results:

• The synthesized CNS possess a thin thickness (~370 nm) with through-penetrated conical pores, creating efficient ion transport pathways.
• Adjusting carbonization temperature allowed for controlled tailoring of the carbon microcrystal structure and interlayer spacing.
• CNS demonstrated a high reversible capacity of 298 mAh g^-1 at 0.1 A g^-1 and excellent stability with 195 mAh g^-1 after 500 cycles at 1 A g^-1.
• Exceptional rate capability was observed, retaining 210 mAh g^-1 at a high current density of 2 A g^-1.

Conclusions:

• The unique structural features of CNS, including conical macropores and tailored microcrystal structure, significantly accelerate ion transfer and electrochemical kinetics.
• These CNS exhibit superior sodium storage performance, including high capacity, excellent cycling stability, and outstanding rate capability, surpassing many existing carbon anodes.
• The developed CNS represent a promising anode material for high-performance sodium-ion batteries.