Explosion Strategy Engineering Oxygen-Functionalized Groups and Enlarged Interlayer Spacing of the Carbon Anode for Enhanced Lithium Storage

Amorphous carbon monoliths with tunable microstructures are candidate anodes for future lithium-based energy storage. Enhancing lithium storage capability and solid-state diffusion kinetics are the precondition for practical applications. Transforming intrinsic oxygen-rich defects into active sites and engineering enlarged interlayer spacing are of great importance. Herein, a novel explosion strategy is designed based on oxalate pyrolysis producing CO and CO2 to successfully prepare ligninderived carbon monolith (LSCM) with active carbonyl (C=O) groups and enlarged interlayer spacing. Explosion promotes the demethylation of methoxyl groups and cleavage of carboxyl groups to form C=O groups. CO2 etches carbon atoms in a short time to improve the heteroatom level, expanding the interlayer spacing. ZnC2O4 is decomposed at 400 degrees C, simultaneously producing CO and CO2, which constructs less C=O groups and large interlayer spacing. MgC2O4 is decomposed at 450 and 480 degrees C, staged-weakly producing CO and CO2, which constructs more C=O groups and larger interlayer spacing. CaC2O4 is decomposed at 480 and 700 degrees C, staged-uniformly producing CO and CO2, which constructs abundant C=O groups and largest interlayer spacing. The LSCM prepared by staged-uniform explosion exhibits high lithium storage capacity, superior rate capability, and cycling performance. The assembled lithium ion capacitor device achieves excellent energy/power densities of 78 Wh kg(-1)/100 W kg(-1) and superior durability (capacitance retention of 8 4.6% after 20,000 cycles). This work gives a novel insight to engineer advanced oxygen-functionalized carbons for enhanced lithium storage.

Automated summary

Lignin-derived carbon monoliths with active carbonyl groups and enlarged interlayer spacing were successfully prepared through oxalate pyrolysis and explosion strategy. These carbon monoliths exhibit high lithium storage capacity, superior rate capability, and cycling performance, making them promising candidates for future lithium-based energy storage.