Kinetics-Favorable Ultrathin NiCo-MOF Nanosheets with Boosted Pseudocapacitive Charge Storage for Quasi-Solid-State Hybrid Supercapacitors
Han Li, Xuefeng Wang, Linlin Dai, Fengjiao Guo, Hongyu Mi, Chenchen Ji, Luyi Sun
Abstract
Bimetallic metal–organic frameworks (MOFs) with an ultrathin configuration are compelling materials for developing high-performance energy storage devices on account of their unique structural merits. Herein, a hydrangea-like NiCo-MOF is well prepared using controllable solvothermal and cation-exchange processes, synchronously achieving bimetallic nodes and hierarchical ultrathin architecture. The structural superiority enables NiCo-MOF of expanded electrons’ transfer pathways and multitudinous electrolytes’ diffusion channels, resulting in a significant enhancement in pseudocapacitive performance. Coupling with the bimetallic nature and constructional advantages, NiCo-MOF shows superior gravimetric capacity (832.6 C g–1 at 1 A g–1) and electrochemical kinetics to those of monometallic Ni-MOF and Co-MOF. Importantly, the quasi-solid-state hybrid supercapacitor (HSC) based on the NiCo-MOF cathode and active carbon (AC) anode delivers a desirable energy density (45.3 Wh kg–1 at 847.8 W kg–1), a favorable power density (7160.0 W kg–1 at 23.3 Wh kg–1), a remarkable cyclability (82.4% capacity retention over 7000 cycles), and a capability of driving miniature electronics, exhibiting its potential in practical applications. This work presents an efficient design strategy to develop kinetics-favorable MOF materials for energy storage.