Explosion Strategy Engineering Oxygen-Functionalized Groups and Enlarged Interlayer Spacing of the Carbon Anode for Enhanced Lithium Storage
Caiwei Wang, Dongjie Yang, Wenli Zhang, Yanlin Qin, Si Huang, Weifeng Liu, Xueqing Qiu, Conghua Yi
Abstract
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 CO 2 to successfully prepare lignin-derived 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. CO 2 etches carbon atoms in a short time to improve the heteroatom level, expanding the interlayer spacing. ZnC 2 O 4 is decomposed at 400 °C, simultaneously producing CO and CO 2, which constructs less C═O groups and large interlayer spacing. MgC 2 O 4 is decomposed at 450 and 480 °C, staged-weakly producing CO and CO 2, which constructs more C═O groups and larger interlayer spacing. CaC 2 O 4 is decomposed at 480 and 700 °C, staged-uniformly producing CO and CO 2, 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.