Unlocking Plant-Derived Potential: Regulating Microcrystalline Structure Design of High-performance Hard Carbon...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Biomass-derived hard carbon (HC) is a key anode material for sodium-ion batteries (SIBs).
• The molecular-level formation mechanisms of HC and microcrystalline carbon evolution are not fully understood.
• Controlling precursor components is crucial for optimizing HC properties.

Purpose of the Study:

• To investigate the effect of steric hindrance on the molecular-level formation of HC from biomass precursors.
• To elucidate the evolution mechanism of microcrystalline carbon in HC anodes.
• To design HC with enhanced ion diffusion kinetics and electrochemical performance for SIBs.

Main Methods:

• Introduction of the concept of "steric hindrance" to control cellulose chain growth.
• Experimental characterization of HC structure and properties.
• Molecular dynamics simulations to understand precursor behavior and carbon evolution.

Main Results:

• Reduced steric hindrance promotes the growth of ordered microcrystalline graphite by decreasing precursor chain rigidity and internal free volume.
• Highly crystalline cellulose facilitates closed pore creation, while lignin and hemicellulose hinder graphitization.
• The optimized HC anode exhibits a high sodium storage capacity (309.7 mAh/g) and excellent cycling stability (>7000 cycles).
• Remarkable electrochemical performance was observed even at low temperatures (-20°C).

Conclusions:

• Steric hindrance engineering offers a novel approach to precisely control the microcrystalline structure of biomass-derived HC.
• This strategy significantly enhances ion diffusion kinetics and sodium storage performance in SIBs.
• The findings provide valuable insights for designing high-performance HC anodes for next-generation energy storage.