Phosphatized mild-prepared-NiCo LDHs cabbage-like spheres exhibit excellent performance as a supercapacitor electrode

Abstract

Layered double hydroxides (LDHs) have been paid more attention in supercapacitors due to their advantages in structure and performance. In particular, NiCo LDHs have been extensively studied due to its high theoretical specific capacity. Unfortunately, the exerted capacity is much lower than the theoretical value due to its poor electron conductivity. In this work, P@NiCo LDHs cabbage-like spheres were successfully synthesized by a mild co-precipitation strategy and a subsequent phosphating treatment method. Owing to the generation of metal phosphides, which is endowed with good electron conduction ability, the specific capacitance of the P@NiCo LDHs (536 C g⁻¹) is 1.88 times greater than the NiCo LDHs (285.8 C g⁻¹) at a current density of 1 A g⁻¹. In addition, the prepared electrode provided a good cycling performance with no difference from the initial capacitance at 10 A g⁻¹ after 5000 cycles. Besides, the symmetric supercapacitor device with vacuum plastic packaging structure was prepared, which exhibits an energy density of 7.83 W h kg⁻¹ at 300 W kg⁻¹. This work indicates that the phosphating strategy is an effective way to improve the performance of LDH-based materials for supercapacitors.