Metal-organic frameworks-derived carbon modified wood carbon monoliths as three-dimensional self-supported electrodes with boosted electrochemical energy storage performance

Wood-derived carbon monoliths, in recent years, have attracted tremendous interest in the field of energy storage, but their electrochemical characteristics are still far from satisfactory. Here, we report a universal and efficient approach for the preparation of structure-engineered, heteroatomfunctionalized and property-boosted wood carbons. A two-step ion-exchange process greatly enriches the nucleation sites of ZIF-8 on the inner wall of wood tracheids, hence leading to a unique carbon/carbon heterostructure after carbonizing and acid-washing. Particularly, the prepared NPCM-900 with a large specific surface area of 708.2 m(2) g(-2), a hierarchical porous architecture and a suitable N content of 2.3% delivers an ultrahigh area-normalized specific capacitance of 23.7 F cm(-2) at 5 mA cm(-2), which stands for a new capacitive record among the wood-based binder-free electrodes. The NPCM-900// NPCM-900 all-solid-state supercapacitor has an admirable energy density of 9.3 Wh m(-2) at 24.9 W m(-2) and a large power density of 248.3 W m(-2) at 4.8 Wh m(-2), while the NPCM-900 based Znion hybrid supercapacitor (NPCM-900//Zn) exhibits a superior energy density of 12.7 Wh m(-2). Furthermore, the NPCM-900//NPCM-900 and NPCM-900//Zn present great stabilities with capacitance retentions of 87% and 85%, respectively, after 5000 cycles. These parameters notably outperform those of most wood-based supercapacitors, endowing the NPCM-900 with extensive prospects for practical use.