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The development of high-performance electrode materials and the rational design of asymmetric structures are the two main keys to fabricating micro-supercapacitors (MSCs) with high energy density. Transition metal compounds, especially nickel–cobalt phosphides and hydroxides, are promising electrode materials with excellent pseudo-capacitance. However, they are rarely used in fabricating asymmetric MSCs (AMSCs) due to the limitations of the preparation method. In this work, we constructed hierarchical Ni–Co–P@LDH nanocomposites with outstanding mass specific capacitance (1980 F g−1 at 1 A g−1) via a multi-step electrodeposition method, which is employed with FeOOH to fabricate an interdigital AMSC device (Ni–Co–P@LDHs//PVA–KOH//FeOOH). The as-prepared device exhibits a high working voltage (1.4 V), a large specific capacitance (24.0 mF cm−2 at 0.14 mA cm−2), a high energy density (6.54 μW h cm−2 at a power density of 100 μW cm−2) and good cycling stability (86.5% of capacitance retention after 5000 cycles). This work may provide novel methods for the synthesis of high-performance nickel–cobalt composite materials and their potential applications in interdigital AMSC devices. [ABSTRACT FROM AUTHOR]