Constructing BiOBr-NiCo2S4 composite with broadened potential window in alkaline electrolytes for supercapacitors

The development of composite materials with extensive potential range is pivotal for the advancement of supercapacitors with elevated specific energy. In this work, BiOBr-NiCo₂S₄ composite was synthesized and supplied a prominent specific capacity of 1280 C g^-1 across a potential window of -1.2 ∼ 0.4 V vs. SCE. A symmetrical liquid capacitor of BiOBr-NiCo₂S₄//BiOBr-NiCo₂S₄ with a voltage of 1.4 V is assembled, which can deliver an impressive specific energy of 40.25 Wh kg^-1 at a specific power of 0.7 kW kg^-1 . From the perspectives of energy band and density of electronic states, the density functional theory (DFT) is employed to discuss the outstanding capacitance performance of BiOBr-NiCo₂S₄. It is presumed that an synergistic effect generated within the BiOBr-NiCo₂S₄ composite, thereby endowing the BiOBr-NiCo₂S₄ composite with outstanding rate performance. This research provides valuable insights for design the electrode materials that possess high specific capacity and broad potential range.