Fully controllable design and fabrication of three-dimensional lattice supercapacitors

Abstract

Supercapacitors have been proven to be a superior candidate for energy storage systems. Yet, most of them are of an approximately two-dimensional structure, without taking full advantage of the spatial superiority to load more mass of active materials. Moreover, three-dimensional (3D) sponge electrodes may hinder ion transmission due to the significant variations in porous structures. In this work, fully controllable 3D lattice supercapacitors with the ordered porous structures were fabricated for the first time via using 3D printing technology. To increase the mass loading capacity, active materials, including metal films, carbon nanomaterials, and transition-metal sulfides, were hierarchically loaded onto the surface of the lattice substrate by using electroless plating, dip-coating, and electrodeposition methods. The as-fabricated CoNi2S4/Ni/octet-truss lattice (OTL) electrode demonstrates a high capacitance until up to 1216 F g–1 (KOH electrolyte). The lattice asymmetric all-solid-state supercapacitors, composed of CoNi2S4/Ni/OTL as anode and carbon materials/Ni/OTL as cathode, display the highest specific capacitance of 23.5 F g–1, a 10.6 Wh kg–1 energy density at the 2488.3 W kg–1 power density, and a robustness (77.3% capacitance retention after 1800 cycles). We expect that the design and fabrication method for the fully controllable 3D lattice supercapacitor with hierarchical activating materials can open a door to develop 3D supercapacitors.