Boosting Zn-ion storage capability enabled by enriched micro-mesoporous sheet-like carbon cathode

Aqueous zinc-ion capacitors (ZICs) exhibit significant developmental potential in the field of renewable energy storage and hybrid electric vehicles. However, the large hydrated zinc ion radius and high desolation free energies lead ZICs to perform poor rate performance and specific capacitance. To address the above issues, rational pore distribution optimization and morphology design can increase the surface area and add open porous structures for carbon cathode materials, which will bring efficient pathway for Zn2+/electron migrate/transfer and thus improve the Zn2+ storage performance. Herein, the folded porous carbon nanosheets (PCNs) featured with microporous and mesoporous structures were synthesized via a novel nano-confined active template, using nano-flowering rod-shaped magnesium basic carbonate (Mg2(OH)2CO3) as nano-confined template and physical activating agent. The Mg2(OH)2CO3 prepared by brine-soda ash method possesses the beneficial qualities of an easy synthetic methodology, inexpensive, environmental friendliness, and controllable morphology. The Mg2(OH)2CO3 with 3D morphology as the nano-confined active dual template, which can effectively regulate the micromorphology and porous structure of the PCNs. Benefiting from the large surface and high mesopore content, the PCN-6 ZICs exhibits a specific capacity of up to 121.7 mAh g−1 at 0.1 A g−1, remarkable rate performance (68.5 mAh g−1 at 20 A g−1), and large energy density (95.0 Wh kg−1), accompanied by good cycling stability (93.37 % capacity retention after 8000 cycles). This work will offer a guiding function into the fabrication of porous carbon for ZICs application by utilizing nano-confined strategy.