In situ hydrolysis strategy to synthesis ultrathin CoNi-LDH nanoflowers for High-performance supercapacitors

Cobalt-based metal–organic framework (MOF) is commonly used as templates to prepare layered double hydroxides (LDHs) with specific morphology to improve the pseudocapacitance capacity. A multi-step synthesis method was employed in the reported work to introduce a second metal during the preparation process of bimetallic LDH materials. Herein, we disclosed a facile and efficient one-step in-situ hydrolysis strategy to prepare CoNi-LDH under mild condition using CoNi-MOF precursor, which introduces Ni element in the Co-MOF nucleation process. The method for synthesizing CoNi-LDH with nanoflower structure can omit the past time-consuming synthesis process and the complex modification process. The obtained CoNi-LDH at 60 °C achieves specific capacitance as high as 1634.1F g−1 at a current density of 1 A g−1. The assembled CoNi-LDH-24//RGO ASC deliver high energy density of 48.97 Wh kg−1 at the power density of 787.16 W kg−1, and the capacitance retention after 10,000 cycles can reach 81.7%. This work provides a mild and simple method to synthesize 3D structure LDH materials with excellent supercapacitor performance, and further confirms that the in-situ hydrolysis method is feasible and promising in the preparation of 3D CoNi-LDH nanoflowers.