In Situ Introduction of NiSe₂ to Nickel–Chromium Layered Double Hydroxides for Promotive Aqueous System Asymmetric Supercapacitors

The high theoretical energy storage capacity of nickel-based polyvalent hydrotalcite has garnered significant attention from researchers, positioning it as a promising candidate for electrode materials in the field of supercapacitor energy storage. Unfortunately, as a result of limitations in material synthesis and design, the explicit energy storage capacity of most reported nickel-based hydrotalcite materials falls significantly below their theoretical value. The concept of employing a one-step partial selenized transformation strategy was adopted herein for the surface treatment of nickel–chromium layered double hydroxides (NiCr-LDHs), with the aim to enhance their charge conduction capacity and maximize their energy storage capability. The optimally prepared Se-NiCr-LDHs-1 presented a mass capacitance of 754 F g^–1 at a current density of 1 A g^–1, and the long-term cycle stability of Se-NiCr-LDHs-1 has been significantly improved in comparison to NiCr-LDHs. Besides, at a power density of 1063 W kg^–1, the self-assembled Se-NiCr-LDHs-1//activated carbon (AC) asymmetric supercapacitor (ASC) has a good energy density of 33 Wh kg^–1. Happily, the Se-NiCr-LDHs-1//AC ASC held a 77.52% energy density after 5000 cycles under a current density of 10 A g^–1. In exploration of the development of high-performance supercapacitors, the selenium augmentation strategy is an effective means to increase the explicit capacity of NiCr-LDHs material.