Carbonate doped NiCo-LDH modified with PANI for high performance asymmetric supercapacitors

Abstract

NiCo layered double hydroxide (NiCo-LDH) is a promising electrode material for supercapacitors due to its extremely high pseudocapacitance. However, the electrochemical stability of NiCo-LDH is not high enough, so it generally has a lower rate performance. In this work, we obtained carbonate doped NiCo-LDH grown on polyaniline (PANI-NCLDH/CO₃²⁻) by a simple room temperature titration. When the amount of polyaniline is 25 mg, the synthetic sample used as an electrode provides a specific capacitance as high as 2176 F g⁻¹ at 1 A g⁻¹, and achieves 92.0% and 85.2% retention rates at 20 A g⁻¹ and 50 A g⁻¹. The good rate performance is also reflected in the asymmetric supercapacitor assembled with this sample as the positive electrode. The device shows a maximum energy density of 77.5 W h kg⁻¹ at 375 W kg⁻¹ and an energy density of 27.9 W h kg⁻¹ at 15 001 W kg⁻¹. After 10 000 cycles of constant current charge and discharge tests, there is still a very high retention rate of 80.7%. The outstanding electrochemical performance of the prepared electrode can be attributed to the stable structure after compounding with polyaniline. These findings may provide new ideas for the preparation of electrodes with high electrochemical performances.