Hierarchical MnCo 2 O 4 /NiMn Layered Double Hydroxide Composite Nanosheet Arrays on Nickel Foam for Enhanced Electrochemical Storage in Supercapacitors

Herein, we report on layer‐by‐layer MnCo 2 O 4 /NiMn double hydroxide (LDH) nanosheet arrays (NAs) that are designed and synthesized by in‐situ growing the NiMn LDH NAs onto the surface of the MnCo 2 O 4 NAs. The layer‐by‐layer architecture together with the synergistic effects between the NiMn LDH and MnCo 2 O 4 components, substantially improves the energy storage performance of the composite NAs electrodes. The optimized composite NAs electrode exhibits a high specific capacitance of 3063 F g −1 at 3 A g −1 (four times with respect to the individual MnCo 2 O 4 electrode), a capacitance retention of 2315 F g −1 at 30 A g −1 , and a cycle stability with 94.7 % capacitance retention at 20 A g −1 over 5000 cycles. Moreover, an assembled MnCo 2 O 4 /NiMn LDH//active carbon (AC) asymmetric solid‐state supercapacitor (ASSC) is found to achieve a high energy density of 51.9 W h kg −1 at 806 W kg −1 . These findings might offer a feasible strategy to synthesize the high‐performance MnCo 2 O 4 ‐based composite electrodes for supercapacitors (SCs).