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Cost-effective and high-performance electrode materials for energy storage and conversion are essential for commercial applications. In this work, the influence of solvent on the morphologies of [CH₃NH₃][M(HCOO)₃] precursors was studied to design and synthesize two-dimensional (2D) porous NiCo₂S₄ nanosheets with different structures. As an electrode material for supercapacitors, Microflower-NiCo₂S₄ exhibits excellent capacitance (1,141 F g⁻¹ at 1 A g⁻¹) and stability (88.2% of initial capacitance maintained after 5,000 cycles at 5 A g⁻¹). Moreover, an asymmetric capacitor was constructed using Microflower-NiCo₂S₄ and porous carbon (PC) and demonstrated an energy density of 51.25 Wh kg⁻¹ at a power density of 397.5 W kg⁻¹. When two Microflower-NiCo₂S₄//PC asymmetric supercapacitors were assembled in series, the device supplied power for an alarm clock with dimensions of 6.1 × 6.1 cm² for more than 32 min. Therefore, the preparation of metal sulfides and metal oxides with hollow structures using a [CH₃NH₃][M(HCOO)₃]-template has potential applications in energy storage and conversion.