One-step facile synthesis of nickel-chromium layered double hydroxide nanoflakes for high-performance supercapacitors

Rational design and synthesis of efficient electrodes with pronounced energy storage properties are crucial for supercapacitors. Herein, we report thin NiCr-layered double hydroxide nanoflakes (NiCr-LDNs) for a high-performance supercapacitor. These fabricated NiCr-LDNs, with various Ni²⁺/Cr³⁺ ratios, are one-step controllably synthesized through ultrasonication coupled with mechanical agitation, without hydrothermal treatment or extra exfoliation using organic solvents. Through comparison of different Ni²⁺/Cr³⁺ ratios, the Ni₂Cr₁-LDNs with a 4.7 nm thickness exhibited a superb capacitance performance of 1525 F g^-1 at 2 A g^-1, which is competitive with most previously reported layered double hydroxide (LDH)-based electrodes. These thin nanoflake structures have the potential to reduce the energy barrier and enhance the capture ability of electrolyte ions. Besides, an asymmetric supercapacitor (ASC) assembled using Ni₂Cr₁-LDNs achieved a remarkable energy density of 55.22 W h kg^-1 at a power density of 400 W kg^-1 and maintained high specific capacitance (over 81%), even after 5000 cycles. This work offers an efficient and facile route to fabricating LDH nanoflakes for boosting energy storage capabilities.