Exchanging Anion in CuCo-Carbonate Double Hydroxide for Faradaic Supercapacitors: A Case Study

Area of Science:

• Materials Science
• Electrochemistry
• Nanotechnology

Background:

• Developing advanced electrode materials is crucial for high-performance energy storage devices.
• Copper cobalt carbonate double hydroxide (CCH) serves as a precursor for novel materials.
• Tuning material properties through anion exchange and phase transformation is an active research area.

Purpose of the Study:

• To develop a systematic synthetic method for fabricating superior functioning three-dimensional (3-D) urchin-architectured copper cobalt oxide (CuCo2O4; CCO) and copper cobalt sulfide (CuCo2S4; CCS) electrode materials.
• To investigate the impact of anion exchange and phase transformation on the electrochemical properties of CCO and CCS.
• To construct and evaluate an asymmetric supercapacitor device utilizing the synthesized materials.

Main Methods:

• Anion exchange process applied to copper-cobalt carbonate double hydroxide (CCH) precursor.
• Thermal treatment for CCO synthesis and sulfurization for CCS synthesis.
• Fabrication and electrochemical testing of CCO, CCS, and asymmetric supercapacitor devices.

Main Results:

• CCO and CCS electrodes exhibited significantly higher capacity values (1508 and 2502 C g-1 at 10 A g-1) compared to CCH (1182 C g-1 at 10 A g-1).
• CCS electrodes displayed hierarchical 3-D urchin morphology with enhanced active sites and ion/electron transport.
• The asymmetric supercapacitor demonstrated high specific capacity (287.35 C g-1 at 7 A g-1), excellent durability (94.2% retention over 5000 cycles), and ultrahigh energy/power densities (135.3 Wh kg-1 / 44.35 kW kg-1).

Conclusions:

• Anion exchange and phase transformation are effective strategies for engineering high-performance electrode materials.
• The synthesized 3-D urchin-architectured CCO and CCS materials show great promise for advanced supercapacitor applications.
• This work highlights the potential of manipulating anions and phase transformations to overcome limitations in supercapacitor energy density and rate performance.