Amorphous cobalt hydrogen phosphate nanosheets with remarkable electrochemical performances as advanced electrode for supercapacitors

The development of simple and efficient approaches to achieve high-performance electrode materials for supercapacitors is urgently needed at present. In this work, a facile and efficient hydrothermal approach (50 °C) is reported to prepare flower-like amorphous cobalt hydrogen phosphate (ACHP) architectures with significantly enhanced electrochemical activity as robust supercapacitor electrodes. These ACHP nanoflowers with numerous thin nanosheets are readily grown on nickel foam by using eco-friendly sodium hexametaphosphate (NaHMP) as phosphorus source and their formation mechanism is also revealed. The ACHP displays a high specific capacitance (411.2 F g−1 at 1 A g−1) as well as excellent rate capability (remained capacitance retention of 82.0% at 10 A g−1) due to the unique nanosheet-like architecture and the influence of structural water. In addition, this ACHP also exhibits an ultra-long lifespan that can maintain more than 97.6% capacitance retention after 10000 charge/discharge cycles. Therefore, this easy and effective one-step low temperature hydrothermal method offers a sustainable development strategy for energy storage devices in practical application.