Sonochemical synthesis of battery-type ZnCo2O4 electrode material with huge specific surface area for advanced hybrid supercapacitors
Hongyan Sun, Miao Yu, Gaojuan Wang, Xinxin Han, Yulin Wang, Zheyu Zhang, Chunwang Luo, Xiaohong Liu, Chunju Xu, Huiyu Chen
Abstract
Sonochemistry is a novel and efficient method for the synthesis of electrode materials within micro-/nano-scale. In this work, the ZnCo 2 O 4 nanoparticles (NPs) and chain-like ZnCo 2 O 4 nanostructures , namely ZnCo 2 O 4 –7.5 and ZnCo 2 O 4 –9.5, were sonochemically prepared by controlling the pH value of reaction system combined with an extra calcination . The ZnCo 2 O 4 –7.5 NPs exhibited a larger specific surface area (SSA) of 148.77 m 2 g −1 , and presented better electrochemical properties such as a high specific capacity ( C s ) of 331.2C g −1 under 2 A g −1 along with 82.5 % rate performance at 10 A g −1 . As for the ZnCo 2 O 4 –9.5 nanostructure , it delivered an inferior C s of 274.8C g −1 and showed a moderate rate capability with 75.6 % capacity retention, accordingly. The hybrid supercapacitor (HSC) device was assembled using such ZnCo 2 O 4 –7.5 NPs (ZnCo 2 O 4 –9.5 nanostructure) as cathode and activated carbon (AC) as anode to explore the application potential in the field of electrochemical energy storage . After 7000 cycles at the current density of 8 A g −1 , both ZnCo 2 O 4 –7.5//AC and ZnCo 2 O 4 –9.5//AC HSCs showed outstanding cyclic stabilities with 100.4 % and 105.1 % of initial capacity retention, respectively. Meanwhile, the ZnCo 2 O 4 –7.5//AC HSC delivered a high energy density ( E d ) of 38.1 W h kg −1 at the power density ( P d ) of 1002.0 W kg −1 , and it could still hold 26.3 W h kg −1 at the higher P d of 9136.5 W kg −1 . In contrast, the ZnCo 2 O 4 –9.5//AC HSC presented a slightly inferior E d of 36.8 W h kg −1 at 1104.7 W kg −1 . The both types of ZnCo 2 O 4 –7.5 and ZnCo 2 O 4 –9.5 electrode materials demonstrate excellent electrochemical property, and they can be expected to show brilliant application potential in the field of electrochemical energy storage & conversion when served as electrode materials for high-performance hybrid supercapacitors .